Disorders of Cardiac Function, Heart Failure and Circulatory Shock

Question 1

Understand pericarditis, pericardial effusion and cardiac tamponade

Answer 1

• pericarditis: an acute inflammatory process of the pericardium
• pericardial effusion: accumulation of fluid in the pericardial cavity, usually as a result of an inflammatory or infectious process
• cardiac tamponade: slow or rapid compression of the heart due to accumulation of fluid, pus, or blood in the pericardial sac
• the amount of fluid, the rapidity with which it accumulates, and the elasticity of the pericardium determine the effect the effusion on cardiac function

Question 2

Differentiate chronic ischemic heart disease and acute coronary syndrome

Answer 2

Atherosclerosis is the most common cause of CAD. CAD is divided into acute coronary syndrome (ACS) and chronic ischemic heart disease. ACS represents a spectrum of acute ischemic heart diseases ranging from unstable angina (US) to MI resulting from disruption of an atherosclerotic plaque. Chronic ischemic heart disease is recurrent and transient episode of myocardial ischemia and stable angina resulting from narrowing of a coronary artery lumen due to atherosclerosis and/or vasospasm. The fixed or stable plaque is implicated in stable angina and the unstable plaque in UA and MI. ACS includes UA, non-ST segment elevation myocardial infarction (NSTEMI) and ST-segment elevation myocardial infarction (STEMI). People w/out ST-segment elevation on ECG are those in whom thrombotic coronary occulasion is subtotal or intermittent; whereas those w/ ST-segment elevation are usually found to have complete coronary occulasion on angiography.

Question 3

Differentiate unstable angina from myocardial infarction

Answer 3

UA and NSTEMI differ in whether the ischemia is severe enough to cause sufficient damage to release detectable quantities of serum cardiac markers. Ppl who have no evidence of serum markers for myocardial damage are considered to have UA, whereas a diagnosis of NSTEMI is indicated if a serum marker of myocardial injury is present. A normal EKG DOES NOT mean that there is no unstable angina or MI.

Question 4

Know cardiac serum biomarkers

Answer 4

Cardiac-specific troponin I (TnI) and troponin T (TnT) and creatine kinase MB (CK-MB).
Troponin-T and Troponin-I are specific to cardiac muscle and serve as a primary biomarker for cardiac injury associated with myocardial infarction. After a myocardial infarction, troponin-T and troponin-I are detected in the blood within 3-6 hrs, peak at 12-24 hrs.

Question 5

Differentiate between transmural and subendocardial infarcts

Answer 5

Transmural Infarcts: involve the full thickness of ventricular wall and occur when there is obstruction of a single artery.
Subendocardial Infarcts: involve the inner one third to one half of the ventricular wall and occur more frequently in the presence of severely narrowed but still patent artery.

Question 6

Know various medical managements following myocardial infarction

Answer 6

Thrombolytic therapy
Revascularization interventions: reperfusion refers to the establishment of blood flow via pharmacologic agents (fibrinolytic therapy), Percutaneous coronary intervention (PCI), or coronary artery bypass grafting (CABG).
PCI - Balloon PTCA (percutaneous transluminal coronary angioplasty) involves dilation of a stenotic atherosclerotic plaque with an inflatable balloon. Coronary stenting improves outcomes compared w/ PTCA alone

Question 7

Define cardiomyopathies

Answer 7

a heterogenous group of diseases of the myocardium associated w/ mechanical and/or electrical dysfunction that usually exhibit inappropiate ventricular hypertrophy or dilatation and that are due to a variety of causes that are frequently genetic

Question 8

Understand ineffective endocarditis

Answer 8

Invasion of the heart valves and endocardium by a microbial agent. Formation of bulky, friable vegetations and destruction of underlying cardiac tissues.

Question 9

Describe valvular stenosis and regurgitation

Answer 9

Stenosis : narrowing of the valve opening, so it does not open properly
Regurgitation: distortion of the valve, so it does not close properly

Question 10

Describe two types of ventricular dysfunction (systolic and diastolic)

Answer 10

Systolic dysfunction is a decrease in myocardial contractility and an ejection fraction under 40%.
In diastolic ventricular dysfunction, ejection fraction is normal but relaxation is impaired - leading to a decrease in ventricular filling.

Question 11

Define circulatory failure (shock), list the four basic causes and associated example

Answer 11

an acute failure of the circulatory system to supply the peripheral tissues and organs of the body with an adequate blood supply, resulting in cellular hypoxia

cardiogenic shock - results from ineffective heart pumping. cause is MI. impaired pumping leads to reduced cardiac output, low bp, and restricted movement of oxygenated blood through the circulation. leads to systemic hypotension or pulmonany edema

hypovolemic shock - decreased blood volume. reduced by 15-20%. can result from severe hemorrhage, burns, diarrhea, or polyuria, as occurs w/ diabetes insipidus. problem is that blood and fluid losses in the vascular space lead to deficient venous return and reduced circulation. reduction in the volume of RBCs also reduces O2 transport thr circulation. Inadequate perfusion leads to multiple organ failures.

septic shock - from severe systemic infection

neurogenic shock - from brain/spinal cord injury

anaphylactic shock - severe immunoglobulin E (IgE)-mediated hypersensitivity reaction