Flashcards: Overview of Coronary Artery Disease — 37 cartões

What is the normal oxygen demand and supply for the myocardium at rest and during exercise?

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.

CAD — main cause?

Atherosclerosis (95%)

How does an imbalance between oxygen demand and supply manifest in ischemic heart disease?

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

Stable angina — relief?

Relieved by rest or nitroglycerin

What is myocardial ischemia and how does it relate to imbalance in oxygen supply and demand?

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.

ECG signs — ischemia, injury, necrosis?

T wave inversion, ST elevation, Q waves

What are the common clinical manifestations of myocardial ischemia?

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.

Revascularization methods?

PTCA, stents, CABG

What is organic stenosis in the context of atherosclerosis?

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

Coronary artery — supply?

Oxygenated blood to myocardium

How does atherosclerosis contribute to the development of ischemic heart disease?

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.

Unstable angina vs MI — difference?

Duration, with MI causing necrosis and enzyme rise

What is functional stenosis in the context of coronary artery disease?

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

Myocardial oxygen demand during exercise?

Increases to 9 O2/sec causing ischemia

How does vasospasm contribute to myocardial ischemia in coronary artery disease?

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.

What are the main coronary arteries involved in supplying blood to the heart muscle?

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.

How does atherosclerosis affect coronary artery anatomy and lead to ischemia?

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.

What is stable angina and how is it characterized?

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.

How does effort impact myocardial oxygen demand and supply in stable angina?

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.

What is the pathophysiological basis of rupture in acute coronary syndrome?

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.

How does plaque rupture contribute to the development of acute coronary syndrome?

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.

What are the characteristic ECG changes observed in myocardial ischemia?

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.

How do ECG findings differ between stable angina and acute myocardial infarction?

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.

What role do enzymes play in 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.

Which enzymes are most commonly used to diagnose myocardial necrosis, and what do their elevated levels indicate?

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.

What are the main diagnostic tools used to assess coronary artery disease?

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.

How does imaging contribute to the diagnosis of ischemic heart disease?

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.

What is the primary pharmacological treatment for angina related to nitrates?

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

How do nitrates help in the management of ischemic heart disease?

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.

What is PTCA and how does it function as a revascularization procedure?

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.

How do revascularization procedures like PTCA benefit patients with coronary artery disease?

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.

What is coronary artery bypass grafting (CABG)?

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.

In which clinical situations is CABG typically indicated?

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.

What is pain radiation in ischemic heart disease, and which areas does it commonly radiate to?

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.

How is symptom localization useful in diagnosing coronary artery disease?

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.

What is the primary pathophysiological mechanism leading to flow reduction in ischemic heart disease?

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.

How does flow reduction affect myocardial oxygen supply during exercise in coronary artery disease?

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.