Heart Attacks & Detection

Heart Attacks & Detection

ABHISEK ANAND

A simple definition of a heart attack is a sudden failure of the heart resulting from an occlusion or obstruction of a coronary artery.

SIGNS AND SYMPTOMS

Pressure, a feeling of fullness or a squeezing pain in the center of your chest that lasts for more than a few minutes

Pain extending beyond your chest to your shoulder, arm, back, or even to your teeth and jaw

Increasing episodes of chest pain

Prolonged pain in the upper abdomen

Shortness of breath

Sweating

Impending sense of doom

Fainting

Nausea and vomiting

Risk factors

Age.

Tobacco.

Diabetes.

High blood pressure.

High blood cholesterol or triglyceride levels.

Family history of heart attack.

Lack of physical activity.

Obesity.

Stress.

Illegal drug use.

Gender

High blood pressure

Alcohol

Oral contraceptive pill

COMPLICATIONS

Abnormal heart rhythms

Heart failure.

Heart rupture.

Valve problems.

Tests and diagnosis

Electrocardiogram (ECG).

Blood tests

Echocardiography ("echo")

Cardiovascular magnetic resonance imaging (CMR)

Cardiac stress test

Auscultation

Holter monitor

Electrophysiology study

Sphygmomanometer

Cardiac marker

Coronary catheterization

Fractional flow reserve (FFRmyo)

Intravascular ultrasound (IVUS)

Optical coherence tomography (OCT)

Electrocardiography (ECG or EKG)

Concepts of the electrocardiography

ABHISEK ANAND

C.T.I.T SHAHPUR JALANDHAR

WHAT IS AN ECG & EKG

Allows for detection of

conduction abnormalities

Helpful with non-cardiac

diseases (e.g. pulmonary embolism or hypothermia)

Helps detect electrolyte disturbances (hyper- & hypokalemia)

A recording of the electrical activity of the heart over time.

The ECG Paper

Horizontally

One small box - 0.04 s

One large box - 0.20 s

Vertically

One large box - 0.5 mV

Recall Heart Physiology !

SA node

(Sinoatrial node)

AV Junction

( Atrioventricular (AV) junction)

His-Purkinje

Myocardial cells

Electrical potential

Autonomic Nervous system

Myocardial Cells

Action potential

Depolarization

Repolarization

Critical electrolytes

Sodium, potassium, calcium

Excitability

MAJOR CHANNELS

Standard Limb Leads

Lead Placement

Precordial Leads

Summary of Leads

Limb LeadsPrecordial LeadsBipolarI, II, III(standard limb leads)-UnipolaraVR, aVL, aVF (augmented limb leads)V1-V6

Electrophysiology

A transmembrane electrical gradient (potential) is maintained, with the interior of the cell negative with respect to outside the cell

(-90mv) and (+30mv) inside and outside the cell

Caused by unequal distribution of ions inside vs. outside cell

Na+ higher outside than inside cell

Ca+ much higher

K+ higher inside cell than outside

Maintenance by ion selective channels, active pumps and exchangers

Waveforms

Depolarization of artria

Depolarization of ventricals

Repolarization of the ventricals

Repolarization of purkinje fiber

Cardiac Action Potential

Divided into five phases (0,1,2,3,4)

Phase 0 opening of fast Na channels and rapid

depolarization

Drives Na+ into cell (inward current),

changing membrane potential

Transient outward current due to movement

of Cl- and K+

Phase 1 initial rapid repolarization

Closure of the fast Na+ channels

Phase 0 and 1 together correspond to the R and S waves of the ECG

Cardiac Action Potential

Phase 2 - plateau phase

sustained by the balance between the inward movement of Ca+ and outward movement of K+

Has a long duration compared to other nerve and muscle tissue

Normally blocks any premature stimulator signals (other muscle tissue can accept additional stimulation and increase contractility in a summation effect)

Corresponds to ST segment of the ECG.

Phase 3 repolarization

K+ channels remain open,

Allows K+ to build up outside the cell, causing the cell to repolarize

K + channels finally close when membrane potential reaches certain level

Corresponds to T wave on the ECG

Cardiac Action Potential.

Phase 4 - resting phase (restingmembrane potential)

At (-90mv) stable

Phase cardiac cells remain in until stimulated

Associated with diastole portion of heart cycle

Summary of ionic basis

26

Cardiac action potential in relation with ECG

R

S

T

summary

Introduction to EchocardiographyCardiac Ultrasound

Generation Of An Ultrasound Image

Echocardiography (echo or echocardiogram) is a type of ultrasound test that uses high-pitched sound waves to produce an image of the heart. The sound waves are sent through a device called a transducer and are reflected off the various structures of the heart. These echoes are converted into pictures of the heart that can be seen on a video monitor.There is no special preparation for the test.

Ultrasound gel is applied to the transducer to allow transmission of the sound waves from the transducer to the skin

The transducer transforms the echo (mechanical energy) into an electrical signal which is processed and displayed as an image on the screen.

The conversion of sound to electrical energy is called the piezoelectric effect

Machines

There are 5 basic components of an ultrasound scanner that are required for generation, display and storage of an ultrasound image.

Pulse generator - applies high amplitude voltage to energize the crystals

Transducer - converts electrical energy to mechanical (ultrasound) energy and vice versa

Receiver - detects and amplifies weak signals

Display - displays ultrasound signals in a variety of modes

Memory - stores video display

Cardiovascular magnetic resonance imaging (CMR)

sometimes known as cardiac MRI, is a medical imaging technology for the non-invasive assessment of the function and structure of the cardiovascular system. It is derived from and based on the same basic principles as magnetic resonance imaging (MRI) but with optimization for use in the cardiovascular system. These optimizations are principally in the use of ECG gating and rapid imaging techniques or sequences. By combining a variety of such techniques into protocols, key functional and morphological features of the cardiovascular system can be assessed.

Cardiac stress test

A cardiac stress test with Myocardial Perfusion Imaging (MPI) is a non-invasive test (no

surgery or cutting skin). This test takes four (4) hours and is done in three (3) parts with

breaks between each part. A cardiac stress test with MPI is done to study the blood flow

to your heart during stress and at rest. This test helps your doctor diagnose coronary

artery disease (CAD).

Auscultation: Listening to breath sounds with a stethoscope

What are heart sounds?

Heart sounds are generated by the beating heart and the resultant flow of blood through the cardiac circulation, also referred to as the heartbeat. In cardiac auscultation, the nurse uses a stethoscope to listen for normal heart sounds and any other adventitious sounds or murmurs that may be present.

In healthy adults, there are two normal heart sounds often described as a lub and a dub (or dup), that occur in sequence with each heart beat. These are the first heart sound (S1) and the second heart sound (S2), produced by the closing of the atrioventricular valves (tricuspid and mitral valves ) and the semilunar valves (pulmonic and aortic) respectively.

Auscultation Techniques

AUSCULTATION OF THE HEART

be sure to use both sides of the stethoscope to examine the heart

the diaphragm is best for hearing high-pitched sounds, including S1, S2 and most heart murmurs

the bell is bests for hearing low-pitched sounds, including S3, S4 and a few murmurs (e.g. mitral stenosis)

use LIGHT TOUCH when using the bell. Pressure turns it into a diaphragm

Cardiac Biomarkers

A biomarker is a substance used as an indicator of a biologic state. It is a characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention.

Cardiac markers are substances released from heart muscle when it is damaged as a result of myocardial infarction.

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