Flashcards : Overview of Coronary Artery Disease — 37 cartes

At rest, the myocardium's oxygen demand and supply are balanced at 3 oxygen units per second. During exercise, both increase to 9 oxygen units per second due to increased coronary blood flow.

Atherosclerosis (95%)

When oxygen demand exceeds supply, especially during exertion, it leads to myocardial ischemia, which manifests clinically as angina or other ischemic symptoms.

Relieved by rest or nitroglycerin

Myocardial ischemia occurs when there is an imbalance between myocardial oxygen demand and supply, typically due to reduced blood flow from coronary artery problems, leading to insufficient oxygen being delivered to the heart muscle during increased demand such as exertion.

T wave inversion, ST elevation, Q waves

Myocardial ischemia manifests mainly as angina (stable or unstable), acute coronary syndrome including myocardial infarction, as well as potential sudden death from arrhythmias and subsequent heart failure.

PTCA, stents, CABG

Organic stenosis refers to a fixed, structural narrowing of the coronary arteries caused by atherosclerosis, leading to reduced blood flow to the myocardium.

Oxygenated blood to myocardium

Atherosclerosis causes organic stenosis of coronary arteries, reducing blood flow and oxygen delivery to the heart muscle, especially during increased demand, resulting in myocardial ischemia.

Duration, with MI causing necrosis and enzyme rise

Functional stenosis refers to temporary narrowing of coronary arteries caused by vasospasm rather than fixed atherosclerotic plaques, leading to transient ischemia.

Increases to 9 O2/sec causing ischemia

Vasospasm causes sudden constriction of coronary arteries, reducing blood flow and oxygen supply to the myocardium, which can trigger ischemic episodes even without fixed stenosis.

The main coronary arteries are the right coronary artery (RCA), the left main coronary artery, which bifurcates into the left anterior descending artery (LAD) and the left circumflex artery (LCX). These arteries supply oxygenated blood to different regions of the heart muscle.

Atherosclerosis causes organic stenosis, typically around 95% of cases, leading to narrowing of the coronary arteries. This reduces blood flow during increased demand, such as exercise, resulting in myocardial ischemia.

Stable angina is chest pain caused by myocardial ischemia due to partial coronary artery stenosis, typically triggered by exertion or stress, lasting less than 20 minutes and relieved by rest or nitroglycerin.

During exercise, myocardial oxygen demand increases to about 9 Oxygen/sec, but in stable angina with a pathological artery, supply decreases to around 4 Oxygen/sec, leading to ischemia and angina symptoms.

Rupture in ACS occurs when a vulnerable atherosclerotic plaque's fibrous cap tears, exposing the thrombogenic core to blood, leading to platelet aggregation and thrombus formation that can occlude the coronary artery.

Plaque rupture exposes thrombogenic material, triggering thrombosis and sudden occlusion of the coronary artery, which results in myocardial ischemia characteristic of ACS, including unstable angina and myocardial infarction.

ECG changes in ischemia typically include T wave inversion and ST segment depression during the episode; ST elevation indicates ongoing injury or infarction, and the development of Q waves suggests myocardial necrosis.

In stable angina, ECG may be normal or show T wave inversion without persistent ST elevation; in acute MI, there is often ST segment elevation (STEMI) and possibly deep Q waves indicating myocardial necrosis.

Enzymes such as Troponins and CK-MB are released into the blood when myocardial cells undergo necrosis, making them useful biomarkers for diagnosing myocardial infarction.

Troponins (I and T) and Creatine Kinase-MB (CK-MB) are commonly used; elevated levels indicate myocardial cell damage consistent with myocardial necrosis, such as in acute MI.

The main diagnostic tools include ECG, cardiac enzyme tests (like troponins), exercise stress testing (ergometry), coronary CTA or MSCT, and invasive coronary angiography (catheterization). These help evaluate myocardial ischemia, infarction, and coronary artery anatomy.

Imaging modalities such as coronary CTA, MSCT, and invasive angiography visualize coronary artery stenosis, plaque characteristics, and blood flow, aiding in the assessment of the extent and severity of coronary artery disease, and guiding management decisions.

Nitrates, such as nitroglycerin, are used as vasodilators to relax vascular smooth muscle, thereby reducing myocardial oxygen demand and relieving angina symptoms.

Nitrates primarily act as vasodilators, improving coronary blood flow and decreasing preload, which reduces myocardial oxygen demand, making them effective in relieving angina symptoms and preventing ischemic episodes.

PTCA, or Percutaneous Transluminal Coronary Angioplasty, is a minimally invasive procedure that involves inflating a balloon catheter at the site of a coronary artery stenosis to widen the vessel and improve blood flow, often followed by stenting.

Revascularization procedures such as PTCA restore blood flow to ischemic myocardial tissue, relieving symptoms like angina, reducing the risk of myocardial infarction, and improving overall cardiac function.

CABG is a surgical procedure that creates new routes around blocked or narrowed coronary arteries using grafts, typically from the saphenous vein or internal mammary artery, to restore blood flow to the heart muscle.

CABG is usually indicated in patients with multi-vessel coronary artery disease, especially when there is significant stenosis, reduced ventricular function, or failure of medical or less invasive interventions such as PCI, to improve blood supply and reduce symptoms like angina.

Pain radiation refers to the spread of chest pain beyond the source. In ischemic heart disease, it commonly radiates to the left arm, shoulder, jaw, and sometimes the neck or back.

Symptom localization helps identify the affected coronary artery based on the typical radiating patterns of pain, such as jaw or arm pain indicating proximal coronary involvement, aiding in accurate diagnosis and targeted management.

Flow reduction occurs mainly due to organic stenosis from atherosclerosis, vasospasm, or embolism, which decreases coronary blood supply below the myocardial oxygen demand, especially during stress or exertion.

Flow reduction causes inadequate increase in coronary blood flow during exercise, leading to an imbalance where oxygen demand exceeds supply, resulting in myocardial ischemia manifesting as angina.