SGD 1: Acute Myocardial Infarction

PATHOLOGY

Chest Pain

• An unpleasant sensation in the anterior wall of the thorax– actual or potential tissue damage– mediated by specific nerve fiber to the brain -

conscious appreciation may be modified by various factors.

Organ System Character of pain Location of pain Examples

CardiovascularPressureTightnessHeaviness

Retrosternal, radiates to the

neck, jaw, shoulders or

arms

• Coronary artery disease• Ischemic heart disease• Aortic stenosis• Pericarditis• Hypertrophic cardiomyopathy

Pulmonary SharpSubsternal

Unilateral or localized

• Pneumonia or pleuritis• Pulmonary embolism• Pneumothorax• Tumor

Gastrointestinal

BurningPresents

with abdominal

pain

RetrosternalSubsternalEpigastric

• Gastroesophageal reflux disease• Esophageal spasm• Peptic ulcer disease• Biliary diseases• Pancreatitis

Musculoskeletal StabbingDull ache

SuperficialLocalized

• Cervical disk disease• Arthritis of the shoulder and spine• Costochondritis• Intercostal muscle cramps

Condition Location Quality Duration Aggravating or Relieving

Factors

Associated Symptoms or Signs

Angina Retrosternal region; radiates or occasionally isolated to neck, jaw, epigastrium, shoulder or arms—left common

Pressure, burning, squeezing, heaviness, indigestion

<2-10 min Precipitated by exercise, cold weather, or emotional stress, relieved by rest or nitroglycerin; atypical (Prinzmetal’s) angina may be unrelated to activity, often early morning

S4, or murmur of papillary muscle dysfunction during pain

Rest or unstable angina Same as angina

Same as angina but may be more severe

Usually <20 min

Same as angina, with decreasing tolerance for exertion or at rest

Similar to stable angina, but may be pronounced. Transient cardiac failure can occur

Braunwald and Goldman, Primary Cardiology 2nd ed

Condition Location Quality Duration Aggravating or Relieving Factors

Associated Symptoms or Signs

Myocardial infarction

Substernal and may radiate like angina

Heaviness, pressure, burning

Sudden onset, 30 min or longer

Unrelieved by rest or nitroglycerin

Shortness of breath, sweating, weakness, nausea, vomiting

Pericarditis Usually begins over sternum or toward cardiac apex and may radiate to neck or left shoulder; often more localized than the pain of myocardial ischemia

Sharp, stabbing, knifelike

Lasts many hours to days; may wax and wane

Aggravated by deep breathing, rotating chest, or supine position; relieved by sitting up and leaning forward

Pericardial friction rub

Aortic dissection

Anterior of chest; may radiate to back

Excruciating, tearing, knifelike

Sudden onset, unrelenting

Usually occurs in setting of hypertension or predisposition such as Marfan’s syndrome

Murmur of aortic insufficiency, pulse or blood pressure asymmetry; neurologic deficit

Braunwald and Goldman, Primary Cardiology 2nd ed

Chest Pain

(dark red = most typical area, light red = other possible areas)

Atherogenesis

• Developmental process of atheromatous plaques.

Pathogenesis of Atherosclerosis

• Fatty Streak

• Leukocyte recruitment

• Foam Cell formation

• Microvessels

• Plaque evolution

Atherothrombosis

• Arterial Remodelling

• Rupture of Fibrous cap

• Arterial Occlusion

• More fibrous lesion

Risk Factors• Cigarette Smoking • HPN (BP> 140/90 mmHg or on

antihypertensive medication)• Low HDL, Low LDL• DM• Family Hx of premature CHD

– CHD in male first degree relatives<55y/o

– CHD in female first degree relatives<65y/o

• Lifestyle risk factors– BMI = > 30 kg/m²– Physical inactivity– Atherogenic diet

• Age (male>55y/o, female >65y/o)• Sex (Male>Female)• Stress

• Age (55 y/o)• Male• Occupational stress• 40 pack years • Heavy alcoholic beverage

drinker• HPN (2003)• Usual BP 130-80• Highest BP 170/100• Nifedipine 30 mg – irregular

intake• Family Hx of DM, HPN,

Premature CAD

Clinical Features of Angina

• Described as heaviness, pressure, squeezing, smothering, or choking, and only rarely as frank pain.

• Levine’s sign – localization of pain by the pain: placing his hand (clenched fist) over the sternum to indicate sqeezing, central, substernal discomfort.

• Crescendo-decrescendo (2-5 min)• Radiates to either shoulder and to both arms (ulnar

surface of the forearm and hand).• Also arise in or radiate to the back, interscapular region,

root of the neck, jaw teeth and epigastrium.

Types of Angina Pectoris

New York Heart Association Functional Classification

I. Px have cardiac disease but without the resulting limitations of physical activity does not cause undue fatigue, palpitation, dyspnea or anginal pain

II. Px have cardiac disease resulting in slight limitation of physical activity. They are comfortable at rest. Ordinary physical activity results in fatigue, palpitation, dyspnea, or anginal pain.

New York Heart Association Functional Classification

III. Px have caridac disease resulting to marked limitation of physical activity. They are comfortable at rest. Less than ordinary physical activity causes fatigue, palpitation, dyspnea, or anginal pain.

IV. Px have cardiac disease resulting in inability to carry on any physical activity without discomfort. Symptoms of cardiac insufficiency or of anginal syndrome may be present even at rest. If any physical activity is undertaken, discomfort is increased.

Canadian Cardiovascular Society Classification of Angina

I. No angina with ordinary activity. Angina with strenuous, rapid, or prolonged exertion

II. Slight limitation of ordinary activity; angina when walking up stairs briskly, or walking on a cold or windy day

III. Marked limitation; angina when walking at normal pace up flight of stairs, or walking 1-2 blocks distance

IV. Angina on minimal exertion or at rest

WHO Criteria for AMI

Classic WHO Criteria: two (probable) or three (definite) of the following criteria are satisfied:

• Clinical history of ischemic type chest pain lasting for more than 20 minutes

• Changes in serial ECG tracings • Rise and fall of serum cardiac biomarkers such as CK-MB fraction

and troponin

Revised (2000) Cardiac troponin rise accompanied by either typical symptoms, pathological Q waves, ST elevation or depression or coronary intervention are diagnostic of MI.