Myocardial Infarction• Myocardial Infarction

Myocardial Infarction blood vessels that supply blood to the heart are

blocked, preventing enough oxygen from getting to the heart.

Insufficient blood supply to the myocardium can result in

myocardial ischemia, myocardial injury or myocardial infarction, or all three.

Myocardial InfarctionMyocardial ischemia generally appears first in the sub-

endocardial region and is more extensive

farthest from the blood supply greater intramural tension and More need for oxygen.

Myocardial InfarctionSubendocardial ischemia: repolarization normally from

Epicardium-to-Endocardium.delayed recovery in the Subendocardial

region due to ischemia merely lengthens repolarization.

results in prolonged QT interval or increased amplitude of T wave or both

Myocardial InfarctionSubepicardial or transmural ischemia ischemia extends subepicardially. more visible effect on recovery of subepicardial

cells.Recovery is more delayedthe subendocardial muscle fibers seem to recover

first. Repolarization is endocardial-to-epicardial,resulting in inversion of the T waves in leads

overlying the ischemic regions.

Myocardial InfarctionInjuryto the myocardial cells results when the ischemic

process is more severe. Subendocardial injury - ST segment depression,subepicardial or transmural injury - ST segment

elevation. ischemia, injury and myocardial infarction

frequently coexistproducing mixed and complex ECG patterns.

Myocardial InfarctionMyocardial infarction necrosis or death of myocardial cells. The left ventricle - predominant site right ventricular infarction occasionally coexists. pathological Q waves in transmural myocardial infarction initial downward deflection of 40 msec or more in any

lead except III and aVR. infracted muscle is electrically inert vector directed away from the site of infarction seen as a negative Q wave

Myocardial Infarction

Transmural Infarction - Rupture

Myocardial InfarctionDuring acute myocardial infarction various stages of

myocardial damage can coexistthe central area of necrosis surrounded by an area of injurysurrounded by an area of ischemia. Transient myocardial ischemia produces T wave,

and sometimes ST segment abnormalitiescan be reversible without producing permanent

damagenot accompanied by serum enzyme elevation.

Causes blood clot that blocks one of the coronary

arteries. atherosclerosis• The slow buildup of plaque, almost block one of

your coronary arteries, more likely during exercise• The plaque itself develops cracks, platelets form a

blood clot, that can completely blocks the passage of oxygen-rich blood to the heart.

• sudden, significant emotional or physical stress, including an illness, can trigger a heart attack.

Atherosclerosis

Atherosclerosis –Hardening of Artery

Atherosclerosis

Infarction

Atherosclerosis

Infarction

Infarction

Risk factors • for heart attack and coronary artery disease include:• Increasing age (over age 65)• Male gender• Diabetes • Family history of coronary artery disease - genetic• High blood pressure • Smoking • Too much fat in your diet• high LDL ("bad") cholesterol and low HDL ("good")• Chronic kidney disease

Risk factors

Risk factors

Symptoms• Chest pain major symptom, may move from your chest to

your arms, shoulder, neck, teeth, jaw, belly area, or back.• severe or mild. It can feel like:• A tight band around the chest• Bad indigestion • Something heavy sitting on your chest• Squeezing or heavy pressure• usually lasts longer than 20 minutes. • Rest and a medicine called nitroglycerin may not

completely relieve the pain. • Symptoms may also go away and come back.

sudden cardiac arrest

Symptoms• Other symptoms of a heart attack include:• Anxiety • Cough • Fainting • Light-headedness, dizziness • Nausea or vomiting • Palpitations • Shortness of breath • Sweating - extreme• "silent heart attack" is a heart attack with no symptoms -

elderly, people with diabetes, and women, no chest pain but unusual symptoms

unusual symptoms

Exams and Tests• A heart attack is a medical emergency. • seek immediate medical help. • DO NOT try to drive yourself to the hospital. • DO NOT DELAY - greatest risk of sudden cardiac

death in the early hours of a heart attack.• You may have a rapid pulse. • Your blood pressure may be normal, high, or low.

Exams and TestsTests to look at your heart include:• Coronary angiography • CT scan • Echocardiography • Electrocardiogram (ECG) -- once or repeated• MRI • Nuclear ventriculography • Blood tests - show if heart tissue damage• Troponin I and troponin T• CPK and CPK-MB • Serum myoglobin

Tests EKG

TESTs

Echocardiography

CT Scan

Angiography

Treatment• need to stay in ICU.• arrhythmias - leading cause of death in the first

few hours -medications or electrical cardioverson /defibrillation.

• oxygen• An intravenous line, urinary catheter

Treatment

ANGIOPLASTY AND STENT PLACEMENTcalled percutaneous coronary intervention

(PCI)preferred emergency procedure, within 90

minutes but not later than 12 hours after MIopen narrowed or blocked blood vessels.A stent is often placed after angioplasty. prevent the artery from closing up again.

Treatment

THROMBOLYTIC THERAPY (CLOT-BUSTING DRUGS)• drugs to break up the clot. • Best if given within 3 hours of first felt chest pain. Contraindications :• intracranial hemorrhage• Brain tumors or blood vessel malformations• Stroke within past 3 months• Head injury within past 3 months• Pregnant women • Severe high blood pressure

Angioplasty

Treatment

• OTHER MEDICINES FOR HEART ATTACKS• Nitroglycerin helps reduce chest pain. • Antiplatelet medicines help prevent clots. Aspirin,

clopidogrel (Plavix), daily for at least one year• Beta-blockers - atenolol help reduce the strain on

the heart and lower blood pressure.• ACE inhibitors - enalapril, or captopril, to prevent

heart failure and lower blood pressure.• Lipid-lowering medications, statins, lovastatin,

Treatment

• CORONARY ARTERY BYPASS SURGERY• narrowing of the left main coronary artery -

emergency CABG).

CABG

Management

Healthy Diet

Regular Exercise

Possible Complications• Cardiogenic shock • Congestive heart failure • infarct extension - rupture of the heart• Damage to heart valves or the wall• pericarditis)• ventricular tachycardia and ventricular fibrillation• pulmonary embolism• Stroke - Blood clot to the brain • Side effects of drug treatment

Stroke - CVA

Prevention• BP, blood sugar, and cholesterol under control.• Don't smoke.• 1 glass of alcohol each day. larger amounts does more

harm than good.• low-fat diet rich in fruits, vegetables and low in animal

fat. fish twice a week.• Exercise daily or several times a week.• Lose weight if you are overweight.• one or more risk factors Aspirin therapy• regular follow-up cardiac rehabilitation program • Always follow the exercise, diet, and medication plan

Myocardial InfarctionTwo types of myocardial infarction on EKG:1. Q wave infarction - presence of pathological Q

waves, also called transmural infarction.2. Non-Q wave infarction - presence of ST

depression and T wave abnormalities.• Elevation of serum enzymes is expected in both

types of infarction. • In the absence of enzyme elevation, ST and T

wave abnormalities - due to injury or ischemia rather than infarction.

Site of infarctionFairly accurately from analysis of the 12-lead ECG. • Inferior (or diaphragmatic) wall: II, II and aVF• Septal: V1 and V2• Anteroseptal: V1, V2, Vf3 and sometimes V4• Anterior: V3, V4 and sometimes V2• Apical: V3, V4 or both• Lateral: I, aVL, V5 and V-6• Extensive anterior: I, aVL and V1 through V6

Posterior wall infarction - tall R waves in V1 and V2.

Site of infarctionThe classic changes seen during acute infarction. necrosis (Q waves) injury (ST elevation), and ischemia (T wave inversion) In recovery the ST segment that normalizes earliest, then the T wave; the Q wave usually persists. the age of the infarction, roughly estimated from

appearance of ST segment and T wave. Q wave in the absence of ST and T wave generally

indicates prior or healed infarction.

ST segment elevation and T wave abnormalities

Other causes of ST segment elevation• Acute pericarditis: ST elevation is generally diffuse

and not accompanied by reciprocal depression of the ST segment in other leads.

• Early repolarization: particularly young patients without known disease.

• Ventricular aneurysm: persistent aneurysm in the region of infarction, ST segment elevation may persist indefinitely.

Abnormal T waves conditions other than myocardial ischemia:• Hyperventilation• Cerebrovascular disease• Mitral valve prolapse• Right or left ventricular hypertrophy• right or left bundle branch block• Ventricular preexcitation• Myocarditis• Electrolyte imbalance• drugs - digitalis and antiarrhythmic agents• No obvious cause, particularly in women

Myocardial infarction• the death of a portion of heart muscle in an area

where there is sudden loss of blood supply. • Death of the heart muscle often causes chest pain• electrical instability of the heart muscle tissue• rapid and disorganized heartbeat - ventricular

fibrillation.• cannot pump/deliver oxygenated blood to brain.• Permanent brain damage and death can occur

unless oxygenated blood flow is quickly resumed

Myocardial infarction• usually by complete blockage of coronary artery

by blood clot. • advanced coronary artery disease, having fatty

deposits, is damaged. • blood clot on the damaged surface• Chest pain or pressure is a common symptom.• Cardiac chest pain is often vague, dull, pressure or

constricting band-like sensation, squeezing, heaviness, or discomfort.

Consequences A heart attack is potentially very serious, can lead to full recoverychronic disabling condition permanent brain damage, rapidly fatal and Death, unless blood flow is quickly resumed.

Invasive Procedures• Coronary (balloon) angioplasty: A thin catheter is

inserted into the blocked artery with a tiny balloon on the end. it is expanded to keep the artery open and the catheter is removed.

• Stents: The insertion of a stent is similar to coronary angioplasty except that over the balloon is a small metallic tube (a stent) that stays in place to keep the artery open while the catheter and the balloon are removed.

• Atherectomy: laser cuts away the plaque• Brachytherapy: Radiation to the blockages to remove

them from recurring after angioplasty.

Coronary Blood Flow