Heart Failure & Sudden Cardiac Death

Question 1

What is heart failure (HF)?

Answer 1

Occurs when the heart cannot generate sufficient output to meet the metabolic demands of the tissues or can only do so at higher-than-normal filling pressure.

Question 2

What can cause high output failure in heart failure?

Answer 2

Greatly increased tissue demands, as in hyperthyroidism, or decreased oxygen carrying capacity, as in anemia.

Question 3

How does heart failure typically develop?

Answer 3

Gradually and insidiously owing to the cumulative effects of chronic work overload or progressive loss of myocardium.

Question 4

What are the two types of dysfunction associated with heart failure?

Answer 4

• Systolic dysfunction
• Diastolic dysfunction

Question 5

What is systolic dysfunction?

Answer 5

Results from inadequate myocardial contractile function, usually as a consequence of ischemic heart disease or hypertension.

Question 6

What is diastolic dysfunction?

Answer 6

Refers to an inability of the heart to adequately relax and fill, which may be a consequence of several conditions such as massive left ventricular hypertrophy.

Question 7

What percentage of heart failure cases are attributable to diastolic dysfunction?

Answer 7

Approximately ½ of HF cases.

Question 8

What are some causes of heart failure?

Answer 8

• Valve dysfunction (e.g., due to endocarditis)
• Rapid increases in blood volume or blood pressure

Question 9

What are the hemodynamic changes that occur when the heart fails?

Answer 9

• Increase in end-diastolic ventricular volumes
• Increased end-diastolic pressures
• Elevated venous pressures

Question 10

What is congestive heart failure (CHF)?

Answer 10

Heart failure is also known as congestive heart failure.

Question 11

What are the compensatory mechanisms the cardiovascular system uses in heart failure?

Answer 11

• Frank-Starling mechanism
• Activation of neurohumoral systems
• Myocardial structural changes

Question 12

What does the Frank-Starling mechanism involve?

Answer 12

Increased end-diastolic filling volumes dilate the heart and cause increased cardiac myofiber stretching, increasing cardiac output.

Question 13

What happens when the patient develops decompensated heart failure?

Answer 13

The failing muscle is no longer able to propel sufficient blood to meet the needs of the body.

Question 14

What is the role of norepinephrine in heart failure?

Answer 14

Increases heart rate and augments myocardial contractility and vascular resistance.

Question 15

What is the consequence of myocardial hypertrophy?

Answer 15

The oxygen requirements of hypertrophic myocardium are amplified due to increased myocardial cell mass.

Question 16

What are the common causes of left-sided heart failure?

Answer 16

• Ischemic heart disease (IHD)
• Systemic hypertension
• Mitral or aortic valve disease
• Primary diseases of the myocardium (e.g., amyloidosis)

Question 17

What are the gross morphological features of the heart in left-sided heart failure?

Answer 17

Left ventricle hypertrophied and can be dilated, except for failure due to mitral valve stenosis or restrictive cardiomyopathies.

LV diastolic dysfunction or dilation w/ mitral valve incompetence causes secondary dilation of the left atrium, increasing the risk of AFib. This in turn results in blood stasis, particularly in atrial appendage, which is a common site of thrombus formation.

Question 18

What are the clinical features of left-sided heart failure?

Answer 18

• Dyspnea on exertion
• Orthopnea
• Paroxysmal nocturnal dyspnea
• Cardiomegaly
• Tachycardia

Question 19

What is right-sided heart failure often linked to?

Answer 19

Left-sided heart failure.

Question 20

What are the gross morphological features of the liver in right-sided heart failure?

Answer 20

• Congestive hepatomegaly
• Nutmeg liver
• Congestive splenomegaly

Increased size & weight of liver; nutmeg = congested centrilobular areas w/ surrounding non-congested peripheral parenchyma

Question 21

What are the clinical features of right-sided heart failure?

Answer 21

• Hepatic and splenic enlargement
• Peripheral edema
• Pleural effusion
• Ascites

Question 22

What is sudden cardiac death (SCD)?

Answer 22

Unexpected death caused by fatal arrhythmia, such as sustained ventricular fibrillation or asystole.

Question 23

What are the main pathologies associated with sudden cardiac death (SCD)?

Answer 23

• Coronary heart disease
• Ischemic heart disease

Question 24

What is the leading cause of mortality in Guyana?

Answer 24

Cardiovascular diseases (CVDs).

Question 25

What is the essential feature of hypertensive heart disease?

Answer 25

Left ventricular hypertrophy, typically without ventricular dilation until very late in the process.

Question 26

What are the microscopic features of left ventricular hypertrophy?

Answer 26

* Increased transverse diameter of myocytes * Prominent nuclear enlargement * Intercellular fibrosis ## Footnote The microscopic changes in left-sided HF are nonspecific: vairable degrees of myocyte hypertrophy and interstital fibrosis.

Question 27

What is typically observed in the hypertrophic left ventricle in cases of heart failure?

Answer 27

The hypertrophic left ventricle typically is dilated. ## Footnote This dilation is a response to increased workload on the heart.

Question 28

What are the microscopic features of myocytes in hypertrophy?

Answer 28

The transverse diameter of myocytes is increased, with prominent nuclear enlargement and hyperchromasia ('boxcar nuclei'), as well as intercellular fibrosis. ## Footnote These features indicate cellular stress and damage.

Question 29

What macroscopic finding may be observed in sudden cardiac death (SCD)?

Answer 29

Some macroscopic findings may include: * Left ventricular hypertrophy * Atherosclerotic plaques in coronary arteries as in the case of CAD * Fibrotic scars from infarcts ## Footnote These findings can vary depending on the underlying condition that caused SCD.

Question 30

What microscopic features are associated with sudden cardiac death (SCD)?

Answer 30

Microscopic features may include: * Cholesterol clefts & Foam cells (like CAD) * Granulation tissue * Fibrosis and collagen deposition ## Footnote These features reflect the pathological changes in the arterial wall due to atherosclerosis.

Question 31

True or False: Sudden cardiac death has a single causative factor.

Answer 31

False. ## Footnote SCD can result from multiple underlying conditions, leading to diverse pathological findings.

Question 32

What are the gross morphological features of the lung in left-sided heart failure?

Answer 32

* Congestion (dark discolouration of lung) * Edema (glossy, wet appearance) * Pleural effusion (due to ↑hydrostatic pressure) ## Footnote pulmonary congestion and edema produce heavy and wet lungs.

Question 33

What are the microscopic morphological features of the lung in left-sided heart failure?

Answer 33

* perivascular & interstitial transudates * alveolar septal edema (due to dilated capillaries) * accumulation of edema fluid in the alveolar spaces in chronic cases CHRONIC: hemosiderin-laden alveolar macrophages ## Footnote hemosiderin-laden macrophages: Extravasated red cells and plasma proteins in the alveoli are phagocytosed and digested by macrophages; the accumulated iron is stored as hemosiderin.

Question 34

What are the microscopic morphological features of the liver in right-sided heart failure?

Answer 34

* centrilobular necrotic hepatocytes * cardiac cirrhosis * hemorrhage * hemosiderin-laden macrophages * reversible fatty change ## Footnote cardiac cirrhosis = fibrotic central zones due to severe chronic RSHF

Question 35

LSHF vs RSHF | Results, clinical features, key characteristics

Answer 35

LSHF: pul congestion; pul edema, dyspnea; hemosiderin-laden macrophages in lung RSHF: systemic congestion; peripheral edema, ascites, hepatosplenomegaly; nutmeg in liver