HD1 – Cardiology

The Cardiac Cycle

I) The Cardiac Cycle

A) Steps in the cycle1) The SA node depolarizes, triggering atrial contraction

This generates the P-wave in the ECGThis generates the a-wave in the atrial pressure curve

2) The AV node depolarizes, and begins transmitting an impulse through the bundle of His and Purkinje system

Depolarization of the AV is not registered in the ECG due to the small tissue mass3) As the ventricles depolarize and contract, ventricular pressure rises

The QRS complex is generated in the ECGThe QRS complex masks atrial repolarization

The rising ventricular pressure closes the mitral valve, generating the first heart sound (S1)The pressure in the ventricle is sufficient to bulge the mitral valve into the left atrium, increasing the pressure of the latter and generating the c-wave in the atrial pressure curve

Isovolumic contraction occurs until the ventricular pressure rises above the aortic pressure, at which point the aortic valve opens and rapid ejection ensues

4) Rapid ejection continues until the ventricular pressure falls below the aortic pressure, at which point the aortic valves close

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Closure of the aortic valves generates the second heart sound (S2)Ventricular repolarization generates the T-wave in the ECGIsovolumic relaxation continues until the ventricular pressure falls below the aortic pressure, at which point the mitral valve opens and rapid filling ensues

As the pressure in the left atrium falls (as a result of blood rapidly flowing into the left ventricle), the notable y-descent of the atrial v-wave is generated

5) Rapid filling continues until the pressures equalize and/or depolarization of the SA node restarts the cycle

B) Features of the ECG1) Electrical signals (e.g. depolarization) precede myocyte contraction, which precedes blood flow2) Because it takes time for the myocytes to contract/relax, the increase in left ventricular pressure

begins slightly after the QRS complex and persists after the T-waveC) Features of the pressure curves

1) Preload is estimated by the end diastolic pressure in the left ventricle2) Afterload is estimated by the aortic systolic pressure

II) The Heart SoundsA) S1

1) Represents closure of the mitral/tricuspid valves2) Auscultated best at the apex3) Intensity depends on several factors

Leaflet mobilityPosition of the leaflets at the onset of contraction

The further apart the leaflets are at the onset of contraction, the louder S1 will beo Indicated in some pathologies (e.g. short P-R intervals and mitral stenosis)

Rate at which pressure rises in the left ventricleB) S2

1) Represents closure of the aortic/pulmonic valves2) Auscultated best at the base3) Physiologic splitting

During expiration, the aortic sound (A2) and the pulmonic sound (P2) are separated by less than 30 milliseconds and are heard as a single soundDuring inspiration, the increased venous return increased filling of the right ventricle increased stroke volume prolonged right ventricular ejection S2 splitting

In adults, A2 is louder than P24) Abnormally wide splitting with normal respiratory variation suggests delayed pulmonic closure

Right bundle branch block, causing delayed depolarization of the right ventriclePulmonary stenosis, mechanically prolonging right ventricular systole

5) Abnormally wide splitting that is fixed suggests an atrial septal defect6) Paradoxical (reversed) splitting is associated with delayed aortic valve closure

Left bundle branch block, causing delayed depolarization of the left ventricleHypertensive cardiovascular disease, mechanically prolonging left ventricular systoleLeft ventricular failure, mechanically prolonging left ventricular systole

C) Gallop sounds (S3 and S4)1) S3 occurs when left atrial pressure dips below left ventricular pressure just after the maximum

pressure gradientAssociated with rapid ventricular filling

2) S4 occurs at the peak of the a-wave when there is a sudden increase in blood filling the left ventricleAssociated with diastolic dysfunction (stiffness) of the ventricles

D) Additional sounds1) Systolic ejection clicks

Early systole2

Bicuspid aortic valvePulmonary stenosisDilation of the aorta/pulmonary artery

Mid-systoleSystolic mitral valve prolapse

2) Opening snap of rheumatic mitral stenosisCaused by the stenotic valve when it reaches maximum excursion

3) Murmurs represent states of turbulent blood flowInnocent states of high blood flowAortic stenosisMitral regurgitation

III) Physical Examination of the Cardiac CycleA) Distention of jugular veins

1) JVP is measured with the patient semi-supine (tilted to 30-45°), taking the measurement vertically from the angle of Louis

2) A normal JVP is measured at < 8 cm of distention3) The a-, c-, and v-waves of the atrial pressure curve can be examined in the right jugular vein4) Associated pathologies

A prominent a-wave represents an increased resistance to atrial flowRight ventricular hypertrophy – creates more resistance due to a less compliant right ventricleTricuspid stenosis – resistance is met at the valve

A prominent v-wave represents atypical ventricular systoleTricuspid insufficiency – regurgitation of blood through the tricuspid valve increases right atrial pressure

A prominent y-descent represents constrictive pericarditisB) Palpitation of the precordium

1) Apical impulseNormal location is the 5th intercostal space, just medial to the mid-clavicular lineCorresponds to the first 1/3 of systole

C) Auscultation of the heart1) Smaller/lighter bell is used to hear low-pitched sounds

Diastolic murmur of mitral stenosisGallop rhythms (S3 and S4)

2) Larger/heavier diaphragm is used to hear high-pitched soundsS1 and S2Ejection and midsystolic clicksMurmur of aortic regurgitation

3) Murmurs will radiate in the direction of flowAortic murmurs will radiate into the neckPulmonic murmurs will radiate towards the left scapula

Distinguishing S1 and S2S1 S2

First of two grouped beats Second of two grouped beatsPrecedes carotid pulse Follows carotid pulse

Louder at the apex Louder at the baseLower pitch and longer in

durationHigher pitch and shorter in duration

Electrocardiography3

I) The ECG Lead SystemA) Polarity of ECG waveforms

1) Depolarization moving towards the positive terminal of a lead generates a positive waveThe depolarization will write the largest deflection in the lead most parallel to its path

2) Depolarization moving away from the positive terminal of a lead generates a negative wave3) Depolarization moving perpendicular to the positive terminal of a lead does not generate a

deflection, rather it is isoelectricThe depolarization will write the smallest deflection in the lead most perpendicular to its path

B) The QRS complex and its variations

C) ECG electrodes1) Bipolar limb electrodes

Lead I – right arm to left arm (+0°)Lead II – right arm to left leg (+60°)Lead III – left arm to left leg (+120°)

2) Unipolar limb electrodes4

aVL = augmented voltage at the left arm (-30°)aVR = augmented voltage at the right arm (-150°)aVF = augmented voltage at the left foot (+90°)

3) The six chest leads (V1-V6)Due to its increased mass, the myocardium of the left ventricle is featured most prominently in the R wave of these leads

R is negative in lead V1R is roughly equal in the positive and negative directions in V3R is positive in V6

II) Interpreting a Normal ECG

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A) Determination of axis1) The heart axis should be between -30° and +90°2) If the R wave in leads I and II are both upright, then the axis is normal

If the R wave in either lead is negative, then the direction of the depolarization must offset by more than 90°, placing it outside the normal range

3) The lead with the largest positive deflection is closest to the axis4) The axis is ~90° away from the lead that is closest to isoelectric

B) Determination of rhythm1) Normal sinus rhythm

Every P-wave is followed by a QRS complexThe P-wave is positive in leads I and II60-100 cycles/min

Sinus bradycardia is <60 cpmSinus tachycardia is >100 cpm

C) Determination of heart rate1) Normal heart rate is 60-100 beats/min2) Calculation using the R-R interval

3) Estimation using the number of boxesEach large box on the ECG represents 200 ms

Each large box is further divided into five small boxes, each representing 40 msDivide 300 by the number of large boxes separating the R-R interval to arrive at an estimation of heart rate

3 boxes of separation 100 bpm4 boxes of separation 75 bpm5 boxes of separation 60 bpm

D) Measurement of intervals1) P-R interval (120-200 ms)

Prolonged in AV blockShortened in pre-excitation

2) QRS complex (≤100 ms)Prolonged in bundle branch and interventricular blocks

3) Corrected QT interval (QTc; <400 ms)Prolonged in hypokalemia, hypocalcemia, congenital channelopathy, and drugs

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III) Interpreting Abnormal ECGsA) P-wave abnormalities (e.g. left atrial enlargement)

1) Classified as a negative P-wave greater than 0.1 mV in magnitude (1 small box) in lead V1

B) QRS abnormalities1) Right ventricular hypertrophy

Increased R-wave in leads overlying the right ventricle (i.e. V1 and V2)Right axis deviation

2) Left ventricular hypertrophyIncreased R-wave in V5 and V6More negative S-wave in V1 and V2ST segment and T-wave changes indicating strain

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3) Right bundle branch blockQRS > 120 msRight ventricular depolarization is delayed, while left ventricular depolarization is unaffectedRSR’ waveform in V1-V3 (“rabbit ears”)

4) Left bundle branch blockQRS > 120 msLeft ventricular depolarization is delayed, while right ventricular depolarization is unaffected

5) Pathologic Q-wavesOccur when a scar from a previous myocardial infarct in present

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Infarcted tissue does not generate electrical forces, causing the overlying electrode to “see” the opposite, left ventricular wall

6) ST segment and T-wave abnormalities following acute myocardial infarction

Structure, Imaging, and Heart Catheterization

I) ImagingA) Chest X-ray (CXR)

1) Typically taken posterior to anterior (PA film) to more finely resolve the heart and avoid artificial enlargement

Right heart bordersAorta (A)Right atrium

Left heart borders

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Aortic knob (AK)Pulmonic arteryLeft ventricleo In PA films, the larger, posterior left ventricle obscures the smaller, anterior right

ventricleIf the left atrium is visible at the borders, then it is pathologically enlarged

Cardiothoracic ratioThe cardiothoracic ratio compares the diameter of the heart to that of the thoracic cavityThe heart should occupy no more than 50% of the field (i.e., the ratio should be <0.5)

2) Lateral CXRs are useful in assessing the right ventricle and retrosternal air space

If the right ventricle occupies more than 1/3 of the retrosternal air space, then it is enlarged/dilated

3) Pulmonary edemaFeatures

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Increased heart size (CT ratio >0.5)Fluid in pleural space obscures inferior borders (liquid is drawn inferiorly by gravity)Poor oxygenation in lower lung fields constricts the arterioles in that region, shunting blood superiorly and enlarging vessels in the upper lung fieldsBronchi are typically invisible on CXR, but may appear when edematous and thickenedEngorged lymphatics may be present

EtiologiesLeft heart failureMitral stenosis or insufficiencyIncreased intravascular volume (as seen with renal failure)

B) Echocardiography1) General

Echocardiography uses ultrasound to construct images based of acoustic responsesEcho is the most commonly used technique used assess the heartDoppler echo can be used to assess blood flow, valve stenosis, regurgitation, etc.

2) Acoustic windowsDense materials (e.g. bone) totally absorb sound wavesAir filled structures (e.g. lungs) totally reflect sound wavesThe heart must be assessed through “soft tissue windows”

Left parasternal window (between ribs)ApicalSubcostal

3) M-mode echocardiographyPulses are released in rapid succession, forming a composite image over time (analogous to a video)Can relate echo to ECG

4) Two-dimensional (2D) echocardiographyA linear array of transducers scans a single plane simultaneouslyRoutinely uses three imaging planes

Long axis plane (apex to base)Short axis plane (cross section of the heart)o The left parasternal short axis can be used to view the aortic valve and its three leafletso The left parasternal short axis can be used to view anterior and posterior papillary

muscles in the left ventricle11

Four chamber plane (transverse view)

5) Calculation of the ejection fraction

C) Single-photon emission computed tomography (SPECT)1) Radioisotopes are used assess myocardial perfusion

Thallium201

Technitium99m sestamibi

2) Image under several conditions to assess functional perfusion (infarct, inducible ischemia, etc.)RestStates inducing coronary vasodilation

ExerciseAdenosine infusion

Uptake of Radioactive IndicatorRest Vasodilated

Normal + +Infarct - -

Ischemia + -

D) Magnetic resonance imaging (MRI)1) Features

A superconducting magnet detects relaxing hydrogen nucleiDoes not use ionizing radiationDistinguishes tissue contrasts

Can be enhanced with gadoliniumE) Computed tomography (CT)

1) FeaturesMultiple X-ray images are assembled into a compositeContrast can be used to distinguish blood-containing structures

II) Cardiac CatheterizationA) Normal heart catheterization pressures (mmHg)

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B) Right heart catheterization1) Catheter is placed through the right femoral vein or jugular vein2) Right atrial pressure can be used to estimate right ventricular end diastolic pressure3) Pulmonary capillary wedge pressure can be used to assess left atrial pressure

A balloon catheter is placed in the left pulmonic artery and inflated to block flowEventually, the pressure distal to the balloon will equilibrate with that of the left atrium, and the sensor can register this pressure

C) Left heart catheterization1) Catheter is places through the right femoral artery

D) Catheter assessments1) Cardiac output

VO2 is the total oxygen consumptionΔAVO2 is the difference in arterial and venous oxygen saturation

Cardiac index is often obtained by dividing the cardiac output by body surface area

Normal cardiac indices fall within the range of 2.5-4.2 L/min/m2

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2) Systemic vascular resistance (SVR) Normal range is 700-1600 dynes-sec-cm-5

3) Pulmonary vascular resistance (PVR)

Normal range is 20-130 dynes-sec-cm-5

The SVR and PVR are particularly useful in assessing patients in intensive care (e.g. sepsis, shock, etc.)

Ischemia and Angina

I) Coronary CirculationA) Myocardium is flow limited

1) Myocardial oxygen extraction is near maximal at rest (75-80%), leaving little capacity to increase extraction further to meet the demands of exercise/stress

2) Therefore, the only mechanism by which myocardial energy demands can be met is by increasing coronary flow

B)1) Basal viscous resistance2) Autoregulatory resistance

Coronary reactive hyperemia refers to a marked, compensatory vasodilation following periods of ischemia or increased resistanceMediated by metabolic, neurogenic, and endothelial vasodilation factorsAdenosine hypothesis

In times of intense work or ischemia, ATP stores are depleted and [AMP] risesAMP is further degraded to adenosine, which freely diffuses out of the cellAdenosine then acts as a potent arteriolar vasodilator, increasing perfusion to the stressed tissue

3) Compressive resistanceSystole compresses the coronary arteries increased resistance decreased flowIn order to maintain adequate perfusion of the endocardial tissues, the resistance of endocardial arterioles must be lower than that of epicardial arterioles

In coronary artery disease, coronary arterioles begin to dilate (in an effort to increase flow)However, dilation of endocardial arterioles “maxes out” first, and further dilation of the epicardial arterioles begins to starve the endocardium, leading to subendocardial ischemia

C) Determinants of oxygen demand1) Wall tension, estimated by

P = systolic left ventricular pressured = cavity diameterh = wall thickness

2) Heart rate3) Contractility4) Basal metabolic needs

II) Angina PectorisA) Clinical features

1) CharacteristicsDiffuse visceral pain (somewhat difficult to pinpoint)1-10 minutes in durationOften located in substernal, epigastric, or neck regionsRadiation to shoulders, inner arm, and jaw

2) Precipitating events14

ExerciseEmotional stress

3) Aggravating factorsMeals (blood flow to viscera increased)Cold temperaturesTime of day

B) Examination sequelae of myocardial ischemia1) Decreased systolic function dyskinetic apical impulse2) Decreased diastolic compliance appearance of S4 heart sound, indicating rapid ventricular filling

Together, decreased systolic and diastolic function may produce pulmonary congestion rales3) Papillary muscle dysfunction mitral regurgitation, producing a pansystolic murmur4) Increased sympathetic tone diaphoresis and tachycardia5) ST-segment variations are evident in the EKG as ischemia ensues

If the lead is overlying ischemic tissue, ST-segment elevation is observedIf the lead is overlying healthy tissue with deeper ischemia, ST-segment depression is observed

In early cases of subendocardial ischemia, all leads will show ST-segment depressionC) Three categories of angina pectoris

1) Classical (Heberden)Precipitated by stressRelieved by restEKG shows ST-depressionMost cases are due to coronary artery disease

2) Variant (Prinzmetal)Occurs at rest (may have normal exercise tolerance)Often cyclical in onsetEKG shows ST-elevationMost cases are due to spontaneous vasospasm

D) Treatment1) Correct remediable factors

Hypertension, smoking, anemia, obesity, aortic valve disease, etc.2) Medical therapy

Aspirin, antihyperlipidemics, nitrates, β-blockers, calcium channel blockersSee relevant pharmacology lectures for details

3) Surgical therapyRevascularization

Acute Coronary Syndromes I & II

I) Epidemiology of Myocardial InfarctionA) Over 16 million people in the USA have MI/angina

1) 785,000 cases/year with a recurrence rate of 470,000 cases/year2) Additional 195,000 silent MI cases/year

B) Heart disease is the leading cause of mortalityC) Major risk factors

1) Hypertension2) Hypercholesterolemia3) Tobacco use4) Diabetes5) Obesity

II) Pathogenesis of Myocardial InfarctionA) Prerequisites

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1) Endothelial injury2) Platelet activation3) Activation of clotting cascade4) Failure of endogenous antithrombotic mechanisms5) Formation of atherosclerotic plaque

B) Plaque rupture1) Triggers

StressCircadian rhythm (AMI peaks in early morning)Sympathetic activity (exercise, sex, anger, anxiety)Anesthesia/surgeryInfection/inflammation

2) InstigatorsMacrophages (foam cells)

Degrade fibrous cap ruptureProduce tissue factor, a powerful procoagulant

T-cellsPromote smooth muscle cell apoptosisPromote macrophage proliferation

C) Platelet adhesion1) Platelets bind to the exposed collagen of the endothelial basement membrane and activate, releasing

several factorsADPPlatelet derived growth factor (PDGF)FibrinogenThromboxane A2

2) Platelets aggregate to one other via glycoprotein IIb/IIIa (GP IIb/IIIa) receptors and fibrinogen linkers

3) A platelet plug forms, and the coagulation cascade ensuesSee pathology notes for an overview of the clotting cascade

D) Endogenous antithrombotic mechanisms1) Inactivation of clotting factors

Antithrombin IIIAntithrombin III couples with heparin sulfate to irreversibly inhibit thrombin

Protein C and protein SJoin together to inactivate factors Va and VIIIa

Tissue factor pathway inhibitorGenerated by factor XaInhibits factor VII

2) Lysis of fibrin clotsTissue plasminogen activator (tPA)

tPA converts plasminogen to plasmin, which degrades the fibrin clot into fibrin split products3) Endogenous platelet inhibition and vasodilation

ProstacyclinEndothelium derived relaxation factor – nitric oxide (EDRF-NO)

E) Formation of coronary thrombus

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III) Pathophysiology of AMIA) Causes

1) Coronary atherosclerosis2) Aortic dissection involving the coronary arteries3) Vasculitis4) Coronary embolism5) Increased blood viscosity (polycythemia, thrombocytosis)

B) Consequences

1) The more extensive the damage, the more likely one is to experience Q-wave abnormalitiesC) Histological changes

D) Gross pathology1) Transmural MI

Spans the thickness of the myocardiumTypically associated with Q-wave MI

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2) Subendocardial MIInjury is limited to the subendocardium

Subendocardium is at the greatest risk for ischemiao Subjected to the highest pressure from the left ventricleo Minimal collateral flowo Epicardial vessels need to penetrate the myocardium

Typically associated with non-Q-wave MI3) Stunned myocardium

Myocardium exposed to hypoxic insult that continues to demonstrate prolonged systolic dysfunction even after coronary flow is restoredMyocardium is reversibly injured, not necrotic

4) Hibernating myocardiumHypocontractile myocardium following chronic hypoperfusionInvolves multi-vessel coronary artery disease, through the LAD is particularly vulnerable

5) Ventricular remodelingChange in shape/thickness of left ventricle following AMIInfarct wall expansion

Augments wall stressImpairs systolic functionPredisposes to LV aneurysm

Non-infarct wall expansion and hypercontractilityNon-infarcted myocardium compensates via Frank Starling mechanism

IV)Diagnosis of AMIA) Symptoms

1) Diffuse substernal chest pain that is difficult to localizePain may radiate to jaw and left arm

2) Dyspnea3) Diaphoresis and cool/clammy skin4) Nausea, vomiting, and weakness5) Fever

B) Physical exam findings1) Vital signs

Hypotension and tachycardia may indicate shockBradycardia may indicate inferior myocardial infarctionHypertension may result from the sympathetic response

2) CardiovascularElevated jugular veins in CHFMurmurs may be auscultatedPericardial rubS4/S3 gallop may indicate CHFDyskinetic bulge may indicate aneurysm

3) PulmonaryRales may indicate CHF

C) Differential diagnosis of chest pain1) Vascular

Aortic dissection2) Myocardial

Hypertrophic cardiomyopathyDissection/rupture

3) Valvular

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Aortic/mitral stenosis4) Pericardium

Pericarditis5) Coronary artery

ST-elevated MI (STEMI)Non-STEMIUnstable angina

D) EKG patterns1) Ischemia

ST-depressionT-wave inversion

2) InjuryST-elevation

3) InfarctionPathologic Q-waves

E) Serum markers1) Lactate dehydrogenase (LDH) and transaminases2) Creatinine kinase MB (CK-MB) and related isoforms3) Troponin

Most specific and long-lasting4) Myoglobin

F) Diagnostic algorithm

G) Diagnostic classification scheme1) Type 1

Spontaneous MI related to ischemia due to primary coronary event2) Type 2

MI secondary to ischemia due to increased oxygen demand or decreased supply3) Type 3

Sudden, unexpected cardiac death4) Type 4

A – MI associated with percutaneous coronary interventionB – MI associated with stent thrombosis

5) Type 5MI associated with CABG

H) Imaging1) Non-invasive

ECHONuclear imaging

2) InvasiveRight heart catheterization

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Left heart catheterizationCoronary angiographyLeft ventriculographyo Can assess ejection fraction

V) Treatment of AMIA) Pharmacological

1) Antiplatelet therapyAspirin

Inhibits COX2 in platelets, preventing production of TXA2

Used in conjunction with P2Y12 inhibitor for increased effectP2Y12 inhibitorsGP IIb/IIIa inhibitors

2) Antithrombotic therapyHeparinXa inhibitors

3) Reperfusion therapyThrombolysisPrimary coronary intervention

BalloonsStentsThrombectomy

4) CardioprotectiveNitrates

Do not reduce mortalityBeta-blockersACE inhibitorsAngiotensin receptor blockers (ARBs)Aldosterone blockers

5) Markers of successful reperfusionResolution of symptomsReturn of ST-segments to baselineEarly “washout” of cardiac markersNormal epicardial coronary flow

VI)Complications of AMIA) Flowchart

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1) Hallmarks of tissue necrosisPapillary muscle ruptureVentricular septal ruptureMyocardial rupture

B) Recurrent ischemia and reinfarction1) Incidence is ~20-30%2) Balloon pumps are contraindicated

C) Congestive heart failure1) Left ventricular dysfunction is the single most important predictor of mortality

Systolic dysfunction = depression in cardiac output and ejection fractionsDiastolic dysfunction = elevated ventricular filling pressure, pulmonary hypertension, and pulmonary congestion

D) Cardiogenic shock1) Systemic hypoperfusion secondary to depressed cardiac output

E) Right ventricular infarction1) Almost exclusively associated with inferior MI

F) Arrhythmias1) Electrical instability (ischemia)

Premature ventricular contractions (PVCs)Ventricular tachycardiaVentricular fibrillationAccelerated idioventricular rhythm

2) Pump failure, pericarditis, pain, pressorsSinus tachycardiaAtrial fibrillationAtrial flutterParoxysmal supraventricular tachycardia (PSVT)

3) Parasympathetic tone, damaged conductionSinus bradycardiaJunctional escape rhythmAV block

G) Left ventricular thrombus and arterial embolism1) Anterior MI is at higher risk

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CHF and Cardiomyopathy

I) IntroductionA) Definitions of heart failure

1) Inability of the heart to pump blood forward at a sufficient rate to meat the metabolic demands of the body (“forward failure”)

Typically leads to inadequate systemic perfusion2) The ability to pump sufficiently only if the cardiac filling pressures are abnormally high (“backwards

failure”This variant is treated more commonly in clinicTypically leads to pulmonary congestion

B) Common causes of heart failure1) Myocardial ischemia (e.g., coronary artery disease)2) Hypertension3) Valvular disease4) Congenital heart disease5) Cardiomyopathies

C) Determinants of cardiac output1) Remember, cardiac output = heart rate x stroke volume2) Stroke volume is dependent on preload, contractility, and afterload

D) Classification of heart failure1) Systolic heart failure

Impaired ventricular contractilityIncreased afterload

2) Diastolic heart failureImpaired ventricular filling

E) Recall that the physiology of the cardiovascular system involves neurohormonal components1) Adrenergic nervous system2) Renin/angiotensin/aldosterone system

F) Classes of heart failure1) Class I – no limitations of physical activity2) Class II – slight limitation of activity with dyspnea and fatigue upon moderate exertion3) Class III – marked limitation of activity with dyspnea and fatigue upon minimal exertion4) Class IV – severe limitation of activity with symptoms even at rest

II) Pressure-Volume LoopsA) Normal pressure-volume loop

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B) Pathologic pressure-volume loops

1) The first image represents increasing preload2) The middle image represents increasing afterload3) The final image represents increasing contractility

III) Assessing Hemodynamic StatusA) “Warm vs. cold”

1) Refers to the degree of systemic perfusion2) The presence of the following findings may indicate inadequate perfusion and demote the patient to

a “cold” statusNarrow pulse pressureSleepy/obtunded stateLow serum sodiumElevated liver enzymes (LFTs)Cool extremitiesHypotension while already taking an ACE inhibitorRenal dysfunctionPulsus alternans

B) “Dry vs. wet”1) Refers to the degree of congestion

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2) The presence of the following findings may indicate congestions and demote the patient to the “wet” status

OrthopneaJVDHepatomegalyEdemaRales (rarely observed in chronic heart failure)Elevated pulmonary artery systolic pressureAbdominojugular reflexPresence of S3 heart sound

C) “Cold and dry” may be the worst combination of status, as it often represents end-stage disease where the heart can no longer function with an otherwise normal/corrected preload

IV)TreatmentA) Goals

1) The most important component of treatment is to identify (and subsequently correct) the underlying cause of disease

Only treating the symptoms is merely palliative, end-stage care...2) Manage heart failure symptoms (e.g. congestion)3) Modulate neurohormonal response4) Improve long-term survival

B) Treating diastolic dysfunction1) Unfortunately, there is no drug capable of improving the ability of the heart to relax2) You need to treat the underlying causes and symptoms as adequately as possible

C) Treating systolic dysfunction1) ACE inhibitor

Use in all patients with ejection fraction <40%May cause renal artery stenosisContraindicated in pregnancy

2) Beta-blockerUse in all patients with ejection fraction <40%May exacerbate asthma and cause arrhythmiasContraindicated in patients with volume overload

3) Aldosterone blockersUse in all patients with ejection fraction <30% and persistent symptoms despite other therapies

4) Digoxin5) Diuretics

V) CardiomyopathiesA) Dilated cardiomyopathy (DCM)

1) All four ventricles of the heart dilate due to some intrinsic weakness systolic dysfunction2) Symptoms resemble congestive heart failure3) Numerous causes

IdiopathicFamilial (genetic)

About 40 genes have been identified as being associated with DCMInflammatory

E.g., viral infectious, connective tissue disorders, peripartum, sarcoidosis, etc.Toxic drugs

E.g. alcohol, chemotherapy, etc.MetabolicNeuromuscular

B) Hypertrophic cardiomyopathy (HCM)24

1) Left ventricle hypertrophy diastolic dysfunction2) Caused by mutations in sarcomere proteins3) Associated with left ventricular outflow obstruction due to systolic anterior motion (SAM) of the

mitral valveThe high-speed flow through the narrowed aortic outflow tract lowers the pressure in that region, drawing the anterior leaflet of the mitral valve towards the hypertrophic ventricular septumIf the leaflet contacts the septum, the aortic outflow tract will be occluded and, because the mitral valve is now open, blood will be forced into the left atrium

4) Other symptomsDyspnea (frequent)Angina

High oxygen demand of increased muscle massNarrowed branches of coronary arteries

SyncopeArrhythmiasOutflow tract obstruction

5) Clinical findingsSystolic murmur that varies with venous return in such a way that HCM can be distinguished from aortic stenosis

During the Valsalva maneuver, venous return is reduced decreased preload contraction of the ventricle stenosis worsens murmur loudensWhen squatting, venous return is increased increased preload expansion of the ventricle stenosis improves murmur softens

In aortic stenosis, the scenario is the oppositeDuring the Valsalva maneuver, venous return is reduced decreased preload less blood moves through stenotic valve murmur softensWhen squatting, venous return is increased increased preload more blood moves through stenotic valve murmur loudens

C) Restrictive cardiomyopathy (RCM)1) Characterized by an abnormally rigid (and thickened) ventricles diastolic dysfunction

Atria enlarge as a result2) Causes

Infiltration of the myocardiumE.g., amyloidosis, sarcoidosis, hemochromatosis, etc.

Fibrosis of the endomyocardiumE.g., metastatic tumors, radiation therapy, etc.

3) Clinical findingsRight heart failure

Including JVD, peripheral edema, ascites, etc.ArrhythmiasHeart block

E.g., exaggerated x- and y-descents on EKG

Atherosclerosis, Risk Factors, and Hypertension

I) AtherosclerosisA) Definition

1) Disease of the aorta and muscular arteries in which the inner layers become thickened by fatty deposits and fibrous tissue

B) Pathogenesisp

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1) Endothelial dysfunction accumulation of lipids recruitment of leukocytes formation of foam cells deposition of ECM (atherosclerotic plaque)

2) Endothelial dysfunctionCauses

High shear stress (branch points of circulation)Toxins (e.g., cigarette smoke)Adverse metabolic environment (e.g., hyperlipidemia, diabetes)Increased oxidative stress activated endotheliumo Impaired permeabilityo Decreased production of NO and prostaglandinso Release of inflammatory cytokineso Production of cell surface adhesion moleculeso Interference with antithrombotic mechanisms

ResultsMonocyte infiltration differentiation into macrophagesMacrophages ingest oxidized LDL foam cellsFoam cells promote smooth muscle cell migration into the subintimal spaceThe recruited smooth muscle cells then deposit collagen fibrous capWhile macrophages attempt to degrade collagen, the smooth muscle cells continually replace it equilibrium

3) Plaque stabilityStable plaque

Small pools of cholesterol estersThick fibrous capFew inflammatory cells

Vulnerable plaqueLarge pools of cholesterol estersThin fibrous capsMany inflammatory cells

Vulnerable plaques grow in two waysSteady accumulation of lipids and growth of the fibrous capGrowth bursts due to plaque rupture or hemorrhage

Plaque rupture/hemorrhageThrombus incorporationOcclusive thrombus recanalizationIntraplaque hemorrhage healing

II) Risk FactorsA) Non-modifiable

1) AgeAs people age, CO begins to fall while TRP begins to rise

2) Gender (male)3) Genetics (lipoprotein A mutations)

B) Modifiable1) Dyslipidemia

Total cholesterol >200 mg/dLTriglycerides >150 mg/dLLDL >130 mg/dL

LDL has the strongest association with atherosclerosisHDL <40 mg/DL

2) Hypertension

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Both systolic and diastolic hypertension increase the risk of coronary artery disease3) Diabetes

Diabetes is a “coronary artery disease equivalent,” granting diabetics the same risk as non-diabetics who have had a prior MI

4) SmokingIntroduction of smoke-free ordinances reduced the incidence of ACS by ~30%

5) Obesity6) Metabolic syndrome

Dyslipidemia, hypertension, insulin resistance, obesityDiagnostic criteria

TGs >150 mg/dLHDL <40 mg/dLWaist circumference >40 inFasting glucose >100 mg/dLBP >130/80 mmHg

C) Risk factors have a cumulative effect on endothelial dysfunctionIII) Workup of Hypertension

A) History1) Duration of hypertension2) History of cardiovascular disease3) Family history of cardiovascular disease4) Lifestyle factors5) Medications

B) Physical exam1) Blood pressure2) Assess pulses3) Fundoscopic examination of small vessels of eye4) Examination of neck, heart, lungs, abdomen, and extremities5) Neurological assessment

C) Laboratory testing1) Urinalysis2) CBC3) Blood chemistry (potassium, sodium, creatinine, fasting glucose)4) Lipid profile5) EKG

D) Target organ damage as a result of hypertension1) Heart disease

LV hypertrophyDiagnose by voltage criteria in V5+V2 and look for strain (ST-depression with T-wave inversion) in V5

Angina and MIHeart failure

2) Cerebrovascular disease3) Nephropathy4) Peripheral artery disease5) Retinopathy

E) Treatment1) Lifestyle modifications

ExerciseLose weightStop smoking/drinking

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Reduce sodium, fat, and cholesterol intake 2) Drugs

Valvular Disease

I) OverviewA) Pressure and volume overload both stimulate adaptations in the myocardium and pulmonary vasculature

1) Physiologic adaptationsPregnancyExercise

2) Pressure overload concentric hypertrophyAortic stenosisHypertension (including pulmonary)Pulmonic stenosis

3) Volume overload eccentric hypertrophyAortic/pulmonic insufficiencyMitral/tricuspid regurgitationShunts

II) Aortic StenosisA) Aortic stenosis refers to narrowing of the aortic valve (and thus aortic outflow tract)B) Etiologies

1) CalcificationPathogenesis is similar (but not identical) to atherosclerosisOsteopontin is deposited in the valve cusps

2) Bicuspid aortic valveCongenital anomaly where two cusps remain fused because a commissure never forms between them

3) Chronic rheumatic heart diseaseC) Pathophysiology

1) Stenosis of the aortic valve requires that the left ventricle to expend more energy to eject an adequate amount of blood

2) Concentric hypertrophy results, leading to diastolic dysfunctionD) Symptoms

1) Syncope2) Angina3) CHF

E) Physical exam1) Late, high-pitched, systolic ejection murmur2) Small and slow carotid upstroke3) S4 heart sound

F) Treatment1) Medical

Diuretics, inotropes, vasodilators2) Surgical

Aortic valve replacement is recommended for many patientsIII) Mitral Stenosis

A) Mitral stenosis refers to narrowing of the mitral valve openingB) Etiologies

1) Rheumatic heart disease (most common)2) Mitral annular calcification3) Single papillary muscle (congenital)

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C) Pathophysiology1) Due to the stenosis, an increased pressure gradient is required to move blood across the mitral valve2) The LV is under filled while the LA maintains an elevated pressure

LA fibrillation may result3) Because LV filling is slow, a long diastole is important

High heart rates, which shorten diastole, result in acute elevations of LA pressure4) The elevated LA pressure is transmitted to the pulmonary vessels, which begin to constrict in order

to compensate for the increased pressureRupture hemoptysisPulmonary edema Kerley B lines

5) Sustained elevation in pulmonary pressure leads to pulmonary hypertension and RV failureD) Physical exam findings

1) EKG findings are often subtleRVH is difficult to identifyBiphasic P-wave in V1Bifid “camel hump” P-wave in leads II, III, and aVF

2) The high LA-LV pressure gradient accentuates the opening and closing sounds of the mitral valveLoud S1 (opening snap)Loud P2 (due to pulmonary hypertension)

3) Low-pitched diastolic rumble4) Dilation of pulmonary artery and right ventricle palpable left pulmonary artery and RV lift

E) Treatment1) Warfarin

Stasis in the enlarged LA leads to thrombus formation and embolization2) Valvuloplasty3) Mitral valve replacement

IV)Volume OverloadA) General principles

1) Volume overload stimulates eccentric hypertrophy with increased compliance2) Increasing chamber size allows pressures to remain “normal”3) Regurgitant volumes are those that are pushed back across their respective valves

Total stroke volume = forward stroke volume + regurgitant volumeRegurgitant fraction = regurgitant volume / total stroke volume

B) Aortic regurgitation1) Etiologies

AcuteEndocarditisAortic dissection

ChronicAortic dilationBicuspid aortic valveRheumatic heart diseaseSyphilitic aortic aneurysm

2) PathophysiologyChronic, compensated aortic insufficiency

In aortic regurgitation, the LV fills from both the LA and the aortaThe extra volume causes the LV to dilate in order to maintain normal diastolic pressureHowever, the LV is forced to compensate for the aortic insufficiency by pumping out additional volume such that enough blood is still reaching the peripheryThis leads to a gradual increase in systolic pressure, especially in elderly patients whose aortas are less compliant

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Uncompensated aortic insufficiencyEventually, the LV becomes fully dilated and LV pressure begins to riseThis is marked by a small (but clinically significant) decrease in ejection fraction

Acute aortic insufficiencyThe rapid change is diastolic volume cannot be fully compensated for by compliance, so the LV pressure risesResembles uncompensated aortic insufficiency, though the LV pressure is much higherEjection fraction decreases because the pressure gradient between the aorta and LV is greatly decreased

3) SymptomsHigh LA pressure

Shortness of breathFatigue

Low aortic pressure and/or high LV diastolic pressureAngina

Dilated LV with increased preloadHeart pounding

4) Physical exam findingsDue to the regurgitant flow…

Diastolic murmuro The murmur is more subtle in acute aortic insufficiency because the aortic/LV pressure

gradient is smallerAustin Flint rumbleS3

Due to the wide pulse pressure…Quinke’s sign (pulsation of the capillary beds in the nails)Corrigan’s pulse (rapid upstroke and collapse of the carotid pulse)Duroziez’s sign (systolic and diastolic murmurs of the femoral artery)

5) TreatmentVasodilators, though their long-term benefit is uncertainValve replacement

C) Mitral regurgitation1) Etiologies

AcuteRupture of papillary muscle or chordae tendinaePerforation

ChronicMyxomatous degenerationDilated LV with distorted geometryRheumatic fever

Severity increases as the pressure gradient between the LA and LV increases2) Pathophysiology

The LV ejects excess volume back into the low-pressure LAAgain, the LV compensates for this forward stroke volume loss by increasing the total stroke volumeIn chronic mitral regurgitation, both the LA and LV dilate in response to the increased volumes, which keeps pressures normal

Pressure in the LA still increases slightly, due to the extra volume coming back from the LVA subtle V-wave may be observed in the EKG

In chronic, decompensated mitral regurgitation, the LV can no longer dilate to maintain the ejection fraction, and the ejection fraction declines

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In acute mitral regurgitation, the LA and LV do not have time to compensate via dilation, so pressures rise dramatically

A prominent V-wave is observed in the EKG3) Symptoms

Elevated LA pressurePulmonary edemaDyspnea on exertionSevere dyspnea in decompensated mitral regurgitation

Decreased forward stroke volumeFatigue

Chronic elevation in LA pressureRight heart failureEdemaVenous distension

4) Physical exam findingsHolosystolic murmur that can be manipulated by altering the aortic/LV and LV/LA pressure gradients

Increasing aortic pressure increased murmurDecreasing aortic pressure decreased murmurIncreased LA pressure decreased murmurDecreased LA pressure increased murmur

D) Mitral valve prolapse1) Occurs when one or both of the mitral leaflets fall back into the left atrium, losing contact with each

otherThis process is potentiated when the heart/LV is smallest (i.e., during systole)

2) Physical exam findingsDilated LV

Displaced/diffuse cardiac impulseIncreased flow across mitral valve

S3High LV diastolic pressure (increased preload)

S4V) Infective Endocarditis

A) Pathogenesis1) Fibrin and platelet vegetations form on damaged endothelium or prosthetic surfaces2) Blood borne bacteria seed these deposits

B) Diagnosis1) Blood cultures of bacteremic individuals2) Observation of vegetations (echocardiogram)3) Presence of new murmur/insufficiency

Arrhythmias

I) Mechanisms of ArrhythmiasA) Automaticity

1) There is normally no electrical connection between the atria and the ventricles except through the AV node

2) Both the SA and AV nodes depolarize spontaneously at some given rate, a feature termed “automaticity”

3) The rate of automaticity can be prolonged by three mechanisms, each resulting in bradycardiaSlowing phase 4 depolarization

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Producing a more negative diastolic repolarization valueEstablishing a higher (less negative) depolarization threshold

B) Overdrive suppression1) After a period of rapid stimulation, the normal automaticity of the SA node is inhibited

A few seconds are needed before the SA node will begin spontaneously depolarizing again2) This effect can be exaggerated in disease states

E.g., tachycardia-bradycardia syndrome

C) Reentrant theories1) Reentrant arrhythmias depend on two items

Conduction velocityRefers to the amount of time it takes for a waveform to travel from one point to another

Refractory periodRefers to the period of time following an action potential during which the voltage-gated Na+

are inactivated and the tissue is unable to generate another action potential2) Reentrant arrhythmias occur when a waveform finds a way to travel around a tissue in a cyclical

manner

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3) For reentry to occur, the conduction time must be greater than the refractory periodThat is, the refractory period must end before the propagating wavefront reaches itThis also gives rise to two mechanisms by which reentrant arrhythmias can be treated

Slow conduction to the point of extinguishment by blocking sodium channelso If conduction is merely slowed (but not extinguished), this can actually potentiate

arrhythmiaProlong the refractory period by blocking potassium channels

4) Wolf-Parkinson-White (WPW) syndrome is an example of a reentrant arrhythmiaIn WPW syndrome, there is an accessory pathway of fast conduction between the atria and ventricles that is separate from the slow conducting pathway of the AV nodeIf conditions are correct, a reentrant arrhythmia can be triggered due to the conduction disparity between these pathsClinically (and diagnostically), the arrhythmia can be corrected (at least temporarily) with a procainamide challenge

5) Atrial flutter is another example of a reentrant arrhythmiaHere, the waveform cycles around the tricuspid valve, passing between it and the inferior vena cavaThe EKG shows a characteristic “sawtooth” appearance

D) Proarrhythmic effects of antiarrhymic medications1) Conduction velocity in myocardium is very dependent on sodium channels

Type I antiarrhythmic drugs slow conduction by antagonizing sodium channels2) Slowing conduction may enhance or stabilize a reentrant arrhythmia

E) Triggered activity1) May occur when the refractory period is prolonged and heart rate is slowed

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2) While the exact mechanism remains obscured, new action potentials may arise out of prolonged inactivation periods (refractory periods)

3) Torsades de pointes is an exampleClassification of Arrhythmias

Bradycardia TachycardiaImpulse Initiation Sinus node dysfunction Enhanced

automaticityTriggered activity

Impulse Propagation AV block Reentrant tachycardia

II) Arrhythmias and EKGsA) Normal sinus rhythm

1) Every P-wave is followed by a QRS complex2) Every PR-interval is identical3) In sinus tachycardia, the rhythm is normal but the rate is >100 bpm

4) In sinus bradycardia, the rhythm is normal but the rate is <60bpm

B) Premature contractions

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1) Premature ventricular contractions (PVCs)Premature and wide ventricular contraction (QRS)After the PVC, the next sinus beat fires when it normally should have

A compensatory pause between the PVC and subsequent sinus beat restores the normal pace

2) Premature atrial contractions (PACs)A narrow QRS complex follows a premature, ectopic (and likely inverted) P-waveThere is no compensatory pause, and a new rate is adopted

C) Escape rhythms1) Junctional rhythm

Rate (~50 bpm) is set by the AV node instead of the SA nodeNarrow QRS complex without a preceding P-waveThe SA node may eventually “wake up” and regain control

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2) Ventricular rhythmRate (~30 bpm) is set by the ventricles instead of the SA nodeWide QRS complexes without a preceding P-wave

D) AV blocks1) First degree

PR-interval >200 ms (or one large block)

2) Second degreeType I

PR-interval prolongs after each beat until a QRS complex is droppedMay observe “grouped beating”

Type IIPR-intervals do not prolong, and a beat is abruptly droppedMay observe “grouped beating”

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3) Third degreeThere is no relationship between P-waves and QRS complexesA junctional or ventricular escape rhythm may predominate

E) Atrial fibrillation1) Characterized by chaotic, high-rate atrial depolarization

As the atria never fully contract, blood pools in the left atrial appendageThis stasis can lead to thrombosis and systemic embolism, requiring anticoagulation therapy

2) Sinus node is suppressed3) AV node may be able to filter some of the incoming action potentials

Leads to an irregular ventricular beat4) Rate control has been shown to be more effective in managing long-term outcomes

Beta-blockersCalcium channel blockersDigoxinHis-bundle ablation and implantation of a permanent pacemaker

F) Atrial flutter1) Example of reentrant arrhythmia (see above)2) Characteristic “sawtooth” appearance3) Conduction pattern of the AV node can vary greatly (4:1 and 2:1 patterns are often observed)

However, the AV node only filters atrial rates that are larger than its native throughput of 250 bpmIf therapy decreases the atrial rate below 250 bpm, the AV node will stop filtering impulses and transfer them all to the ventricles, leading to pronounced ventricular tachycardiaThus, it is imperative that the AV node be slowed before slowing the atrial rate

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G) Supraventricular tachycardias1) There are many different types

AV node reentry tachycardia (AVNRT)AV bypass tractsPrimary atrial tachycardia (may have ectopic focus)

2) Regular rhythm and fast rate with narrow QRS complexes

H) Ventricular tachycardia1) Fast rate with wide QRS complexes2) Includes torsades de pointes3) Treatment thoughts

The majority of “fast and wide” cases are ventricular tachycardiaTreating ventricular tachycardia will not hurt the patient, even if the arrhythmia is supraventricular in originTreating ventricular tachycardia as if it were supraventricular in origin, however, can be harmfulTo be safe, just assume all “fast and wide” cases are ventricular tachycardia and treat accordingly

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I) Ventricular fibrillation (a.k.a. death)1) Irregular, wide waveforms

Congenital Heart Disease

I) IntroductionA) Definition

1) A congenital heart disease is a gross structural abnormality of the heart or intrathoracic great vessels that is actually or potentially of functional significance

2) ExcludesNormal variations of venous anatomyArrhythmiasPDA <14 days of ageBicuspid aortic valveMitral valve prolapse

B) Incidence1) 8 in 1,000 live births2) 27.5 in 1,000 still births

C) Lesion frequency1) VSD is the most common (30%)2) Most lesions are diagnosed at birth (36%)3) Majority of lesions are identified within the first year of life (85%)

II) Fetal Circulation

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A) Normal fetal flow1) Oxygenated blood travels from the placenta to the heart via the fetal venous system

Placenta umbilical vein ductus venosus IVC RA foramen ovale LA LV Brain2) Deoxygenated blood returns to the placenta via the aorta

Body RA RV PA ductus arteriosus aorta umbilical arteries placentaB) Transitional circulation

1) At birth, the LA pressure rises and flow between the atria (via the PFO) ceases2) Simultaneously, PGE1 levels fall as oxygen tension rises and the PDA closes3) Problems

If pulmonary resistance fails to fall, there will be persistent fetal circulation via the PDAIf the PDA closes while there is a critical heart defect, death can occur

Left-sided obstructive lesionso Aortic coarctationo Aortic atresiao Hypoplastic left heartRight-sided obstructive lesionso Pulmonary atresiao Pulmonary stenosisParallel circulationso D-transposition of the great vessels

III) Aortic CoarctationA) Features

1) With a PDA, much of the blood flowing to the lower body will be deoxygenated2) Closure of the PDA will cause blood flow to the lower body to cease

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B) Diagnosis1) Presentation

Cardiogenic shockPallor, tachycardia, tachypnea, hypotension

2) Physical examDiminished femoral pulsesBP differential between arms and legsLower extremity cyanosisIncreased S2

3) ImagingCXR shows cardiomegaly and pulmonary edemaUltrasound defines the coarctation and status of the ductus arteriosus

C) Treatment1) Reopen/stabilize the ductus arteriosus (PGE1)2) Inotropes3) Surgical repair

IV)Pulmonary Stenosis/AtresiaA) Features

1) The increased pressure in the right heart may force deoxygenated blood across the foramen ovale2) Closure of the PDA will cause blood flow to the lungs to cease

B) Diagnosis1) Presentation

Profound hypoxemia that is unresponsive to oxygenTachycardiaTachypneaHepatomegaly

2) Physical examSingle S2 (no splitting)Systolic ejection murmur at left upper sternal borderBlowing pansystolic murmur at left lower sternal border

3) ImagingCXR shows cardiomegaly and oligemia (lack of blood) of lung fieldsUltrasounds defines the pulmonary obstruction and size of the right ventricle

C) Treatment1) Reopen/stabilize the ductus arteriosus (PGE1)2) Inotropes3) Surgical repair

V) D-Transposition of the Great VesselsA) Features

1) Most common cyanotic heart anomaly in the neonatal period2) Incompatible with life without communication between the parallel circuits3) Associated with maternal diabetes

B) Diagnosis1) Presentation

Cyanosis2) Physical exam

RV impulse at lower sternal borderProminent S2 (now due to pulmonic closure)

3) ImagingCXR shows cardiomegaly, increased pulmonary markings, and “egg-on-a-string” appearance

4) Treatment (medical emergency)41

5) Reopen/stabilize the ductus arteriosus (PGE1)6) Surgical repair

Balloon septostomy (Rashkind) permits blood mixing and survivalArterial switch procedure

VI)Ventricular Septal DefectA) Features

1) Most common congenital heart anomaly50-80% of small to moderate VSDs will close before age 2

2) Blood flows from the LV to the RV3) Left ventricular and left atrial dilation result4) Associated with fetal alcohol syndrome

B) Diagnosis1) Presentation

Symptoms are typically absent at birth, but develop within the first 2-3 months of lifeFailure to thrive

Increased caloric need due to increased work of breathingTachypnea

Nasal flaring, rib retractionTachycardia

2) Histological findingsNeonates have medial hypertrophy of the pulmonary arteriesThis hypertrophy regresses over the first 2-3 months of life, and pulmonary resistance fallsDecreased pulmonary resistance increased pulmonary blood flow increased shunting through VSD RVH pulmonary hypertension reversal of shunt Eisenmenger syndrome

3) Physical examHepatomegalyDiaphoresis with feedingHolosystolic murmur at left lower sternal borderMid-diastolic rumble at apex (due to increased mitral flow)

4) ImagingCXR reveals cardiomegaly, increased pulmonary vasculature, and left atrial enlargementUltrasound visualizes defect

C) Treatment1) Treat symptoms of CHF with diuretics, digoxin, and ACE inhibitors2) Surgical repair

VII) Atrial Septal DefectA) Features

1) Direction of shunting depends on ventricular compliances (e.g., whichever ventricle has a higher resistance)

Left to right shunting is more common2) Types

Secundum (includes PFO)PrimumSinusvenosus

3) Associated with Down Syndrome (trisomy 21)B) Presentation

1) SymptomsCyanosis

2) Physical examSystolic ejection murmurMid-diastolic murmur

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Fixed, widely split S23) Imaging

CXR shows cardiomegalyUltrasounds can visualize anomaly

C) Treatment1) Surgical repair

VIII) Patent Ductus Arteriosus (PDA)A) Features

1) Left to right shunt with varying magnitudeCross-sectional area of PDALength of PDARelative pulmonary and systemic resistances

2) May result in CHF3) Associated with congenital rubella

B) Diagnosis1) Symptoms

Failure to thriveRecurrent respiratory infectionsFatigueDyspneaAtrial fibrillation

2) Physical examContinuous murmurAbnormally wide pulse pressure

3) ImagingCXR reveals cardiomegalyUltrasound can visualize PDA

C) Treatment1) Newborns

IndomethacinFluid restriction

2) Everyone elseSurgical repair

IX)Tetralogy of FallotA) Features

1) Four characteristic malformationsVSDOverriding aortaRV outflow tract stenosisRVH

2) Right to left shunting dependent upon degree of PA obstructionB) Diagnosis

1) SymptomsPeriodic cyanosis (may progress to constant cyanosis)“Tet spells”SquattingNotable for the lack of CHF

2) Physical examPulmonary systolic ejection murmur

3) ImagingCXR reveals a “boot-shaped heart”

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C) Treatment1) Surgical correction

Close VSDRelieve pulmonary stenosis

Summary of Congenital Heart DefectsAcyanotic Cyanotic

VSD (fetal alcohol syndrome)

Transposition (diabetes, 22q11.2)

ASD (trisomy 21) Tetralogy of Fallot (22q11.2)PDA (congenital rubella) Truncus arteriosus (22q11.2)

AV canal (trisomy 21) Tricuspid atresiaCoarctation of the aorta (Turner syndrome, bicuspid aortic valve)

Pericardial Diseases

I) IntroductionA) The pericardium is a two-layered sac

1) The parietal (outer) and visceral (inner) layers are separated by a thin film of fluid2) Functions

Fixes the heart in the mediastinumProvides a low resistance surfaceLimits acute dilationActs as a barrier to infection

3) Congenital absence of the pericardium is generally well toleratedII) Acute Pericarditis

A) Etiologies1) Idiopathic2) Infectious

ViralCoxsackie B virusEchovirusParvovirus B19

TuberculoidSpread from mediastinal lymph nodes

Purulent (bacterial)Pneumococcus or Staphylococcus microbesHematogenous spreadExtension of pneumoniaPerforation (trauma or surgical)

3) Non-infectiousPost-MI

Pericarditis may occur early after transmural MIDressler’s syndrome is an autoimmune phenomenon that may develop weeks to months after MI

Uremic causesMalignant causes

B) Features1) Relatively common and generally benign

Purulent etiologies can be lethal if untreated, and typically require surgical drainageC) Diagnosis

1) Presenting history44

Pleuritic chest pain“Pseudo” dyspnea

Patients take rapid, shallow breaths because taking full/deep breaths is painfulFeverSymptoms of pulmonary disease

2) Physical exam findingsPericardial friction rubs that are heard best during times when the heart is moving

Atrial systole (late diastole)Ventricular systole (because this is the most vigorous movement, rubs are best heard during this phase)Ventricular filling (early diastole)

Pericardial friction rubs may also exhibit evanescence, being heard best while the patient is sitting up and leaning forward

3) Laboratory findingsEKG abnormalities

ST-segment elevation (concave upwards “smile”)o ST-segment elevation in MI is a concave downwards “frown”PR-segment depression (lead II)T-waves invert late (after the ST-segments normalize)

Echo may reveal pericardial fluidSerological tests for viral infectionPPD for TB infection

D) Treatment1) Pain relief

NSAIDsColchicine (approved for gout, but used off-label for pericarditis)

2) Treat underlying illnessTreat malignancies with chemotherapyTreat purulent infections with drainage and antimicrobial therapyTreat connective tissue disorders with steroids (avoid steroids if possible)Treat uremia with dialysis

3) Prognosis depends on the underlying diseaseRecurrence and tamponade are rare

III) Pericardial Effusion and TamponadeA) Etiology

1) Acute pericarditis2) Increased capillary permeability (e.g., myxedema)3) Increased capillary hydrostatic pressure (e.g., CHF)4) Decreased plasma oncotic pressure (e.g., cirrhosis, nephrotic syndrome)5) Lymphatic obstruction (e.g., chylopericardium)

B) Pathophysiology45

1) Chronic accumulations of fluid over time will give the pericardium time to increase compliance such that pericardial pressure rises slowly (only after vast volumes have accumulated)

2) Acute accumulation of fluid will cause rapid increases in pericardial pressure tamponadeDuring inspiration, venous return increases and RV volume increasesThe heart can normally expand to accommodate this transient increase in volumeIn cardiac tamponade, the heart cannot expand and the increase in RV size comes at the expense of a decrease in LV sizeThis reduces LV filling and stroke volume pulsus paradoxus

3) Pulsus paradoxusWhen the heart cannot expand to accommodate the increased venous return associated with inspiration, LV stroke volume will fallThe decreased stroke volume lowers aortic blood pressure during inspiration, which can be measuredPressurize the blood pressure cuff until Korotkoff sounds are heard only on expiration, and note this pressureDecrease the pressure until sounds are heard throughout the respiratory cycle and not this pressureIf the pressure differential is >10 mmHg, then pulsus paradoxus is present

C) Diagnosis1) Clinical features

Sinus tachycardiaHypotensionPulsus paradoxusJVDDiminished heart sounds

2) ImagingCXR may show non-specific findings such as cardiomegalyCT may show pericardial fluidEcho

Pericardial effusionDiastolic collapse of the RV free wallLate diastolic compression of the RASwinging heart in pericardial fluid

3) EKGElectrical alternans

QRS complexes alternate in intensity (observable in leads II or V3)4) Cardiac catheterization will reveal that diastolic pressure has equalized in all four chambers of the

heartThis is diagnostic of cardiac tamponade

D) Treatment1) Medical

Maintain adequate intravascular blood volume (decreased volume may cause fatal heart collapse)Treat underlying disease

2) Percutaneous pericardiocentesis (drain the fluid)Numerous complications, but a necessary procedure nonetheless

3) Surgical windowingIV)Constrictive Pericarditis

A) Features1) The heart becomes encased in a rigid (sometimes calcified) pericardial “shell”2) Ventricle fills in early diastole and then abruptly stops when the non-compliant pericardium is

stretched to its limit46

3) Presents with findings of right heart failure4) Insidious onset delays diagnosis

B) Etiologies1) Idiopathic (>50%)2) Post-infectious (e.g., TB, viral, bacterial, fungal)3) Post chest irradiation4) Post operative

C) Diagnosis1) Clinical presentation

Low cardiac output (fatigue, malaise, weight loss, hypotension, resting tachycardia)Elevated venous pressure (ascites, hepatomegaly, anorexia, edema)

May mimic hepatic cirrhosis in this regard2) Physical exam

Elevated JVPProminent Y-descent in early diastoleKussmaul’s signo Normally, venous pressure falls during inspiration as intrathoracic pressure fallso Kussmaul’s sign is a paradoxical rise in venous pressure during inspiration

This occurs because the withdrawn blood has nowhere to go, seeing as the heart cannot expand to accommodate the incoming volume

Pericardial knockHigh frequency sound that comes 90-120 ms after S2Caused by blood entering a non-compliant ventricle and coming to an abrupt stop

3) Lab testingCXR

Pericardial calcifications (>50%)Pulmonary venous distentionPleural effusions

EKG (rarely diagnostic)Low voltagesDiffuse ST-segment changes

MRI and CT may reveal the thickened pericardiumD) Treatment

1) MedicalDiuretics

2) Surgical pericardiectomyExtensive procedure with variable results

Peripheral Vascular Disease

I) IntroductionA) Functions of the peripheral vessels

1) Delivery of oxygen and nutrients2) Synthesis of bioactive molecules

Vasoactive substances (NO, endothelin)Antithrombotic substances (prostaglandins)

3) Transport of immune cellsII) Diseases of the Aorta

A) Aneurysm1) Defined as an increase in diameter >50%2) True aneurysms

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FusiformSymmetrical dilation of the entire circumference of the vessel wall

SaccularLocalized dilation of a portion of the vessel wall

3) False aneurysmsContained ruptures of the vessel wallCaused by infection and trauma

4) EtiologiesAscending aorta

Cystic medial necrosisHypertensionBicuspid aortic valveConnective tissue diseases (Marfan’s syndrome, Ehlers-Danlos syndrome)

Descending aortaAtherosclerosis

5) Risk of rupture is related to sizeSurgical treatment is available when aneurysms reach critical sizes

B) Dissection1) A tear in the intima creates an accessory path of blood flow through the media2) Clinical features

HistoryAbrupt onset of severe ripping/tearing pain in the anterior chest that migrates as the dissection proceedsHistory of hypertension, bicuspid aortic valve, and/or connective tissue disorder

PresentationHypertensionOcclusion of aortic branch vesselsAortic regurgitationShock (if rupture)

ImagingLarge aortic dilation on CXR and CT

3) TreatmentStop progression of the dissection

Reduce systolic BP to 100-120 mmHgDecrease LV ejection force (β-blockade)

Type A dissectionEarly surgery

Type B dissectionTreat medicallyPercutaneous catheter-based repair

4) ComplicationsRupture into adjacent body cavity (pericardium, mediastinum, thorax, peritoneum)Occlusion of aortic branch vesselsAortic regurgitation

III) Occlusive Arterial DiseasesA) Peripheral atherosclerotic occlusion (peripheral artery disease)

1) FeaturesOccurs predominantly in the pelvic and leg vessels Impairs oxygen supply/demand relationshipRisk factors resemble those for atherosclerosis

2) Manifestations of disease48

AsymptomaticNo clinical complaintMinimal functional impairment

Classic claudicationLower extremity muscle symptomsReproducible onset with exerciseRelief with rest

Atypical leg painLower extremity discomfortInconsistent reproducibility with exerciseIncomplete resolution with rest

3) Clinical featuresHistory

Exertional limitation of lower extremity musclesLocalized pain in lower leg/footPoorly healing leg woundsAbdominal pain after eating (aversion to eating, weight loss)Family history of AAA

Physical examAnkle-brachial index (ABI)o ABI = ankle systolic pressure / brachial systolic pressureo ABR <0.90 indicates diseaseCritical limb ischemiao Non-healing woundo Gangrene

ImagingDuplex ultrasonography shows abnormal blood velocity/waveformMRA and CTA visualize defect

4) TreatmentManage modifiable risk factors

Smoking cessationTreat hypertensionTreat hyperlipidemiaTreat diabetes mellitus

Pharmacological therapyAntiplatelet therapyCilostazol

B) Vasculitis1) Inflammatory damage to vessels

My occlude vessel lumen2) Primary diseases

Takayasu’s arteritis (pulseless disease)Carotid or limb pulses diminished in 80% of patients

Giant cell arteritis (temporal arteritis)Thromboangiitis obliterans (Buerger’s disease)

Superficial vein thrombosis and/or arterial occlusionFrequently affects male smokers

3) Secondary diseasesImmune complex disorders

IV)Aterial Spasm

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A) Raynaud’s phenomenon1) Cold-induced vasospasm of digital arteries2) Triphasic response

BlanchingCyanosisRubor (redness) with rewarming

3) ClassificationsPrimary (Raynaud’s disease)Secondary (due to other pathology)

Connective tissue diseases (scleroderma, SLE)Vibration or thermal injuryBody dyscrasias

4) TreatmentAvoid cold and dress warmlyPharmacologic agents

Calcium channel blockersα-adrenergic receptor blockers

V) Venous DiseaseA) Varicose veins

1) Primary diseaseAffects females much more than malesPathyphysiology

Vessel wall weaknessValvular invompetence (failure of valves to coapt)Increased intraluminal pressure

2) Secondary diseaseOften occurs after DVT when the veins are recanalized (which destroys the valves)

B) Hypertension in microcirculation1) Edema2) Stasis dermatitis3) Ulceration

C) Treatment1) Elevate legs2) Compression stockings3) Occlusive dressing4) Surgery

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