Pathophysiology of Congestive Heart Failure

Question 1

Braunwald’s Definition of Congestive Heart Failure

Answer 1

The inability of the heart to pump blood forward at a sufficient rate to meet the metabolic demands of the body (forward failure)
or
The ability to do so only if the cardiac filling pressures are abnormally high (backward failure)

Question 2

Major Determinants of Cardiac Performance

Answer 2

Heart Rate
Preload
Afterload
Contractility

Question 3

Disorders of Impaired Contractility

Answer 3

Myocardial infarction
Ischemic cardiomyopathy
Dilated cardiomyopathy

Question 4

Disorders of Markedly Increased Afterload

Answer 4

Severe aortic stenosis

Uncontrolled hypertension

Question 5

Disorders with Impaired Ventricular Relaxation/Decreased Filling

Answer 5

Restrictive cardiomyopathy
Acquired or familial hypertrophic cardiomyopathy
Constrictive pericarditis

Question 6

Heart Failure with Preserved Ejection Fraction (Diastolic Heart Failure)

Answer 6

Due to decreased diastolic compliance
Stroke volume is reduce and filling pressures are higher
EF is still normal though, makes it difficult to diagnose clinically

Question 7

Pathophysiology of Right Sided Heart Failure

Answer 7

RV is more compliant than LV (thinner walls, pulmonary vascular resistance is less than systemic)
RV can tolerate larger changes in filling w/o change in pressure
BUT
RV is susceptible to acute changes in Pulmonary Vascular Resistance
Pulmonary disease can cause isolated RV failure

Question 8

Causes of Right Sided Heart Failure

Answer 8

Cardiac: LV failure, mitral stenosis/regurg, acute MI wtih RV infarction, pulmonic stenosis
Pulmonary parenchymal diseases: COPD, interstitial lung diseases (silicosis, pulmonary fibrosis), ARDS (acute respiratory distress syndrome)
Pulmonary Vascular Diseases: pulmonary embolism, primary pulmonary hypertension

Question 9

Compensatory Mechanisms to Maintain Cardiac Output in CHF

Answer 9

Frank-starling mechanism (increase in residual volume aka preload which contributes to greater output on next contraction)
Autonomic nervous system (baroreceptor response)
Renal Compensation (renin-angiotensin-aldosterone system)
Ventricular Remodeling

Question 10

Post-MI Ventricular Remodeling

Answer 10

Any architectural or structural change that occurs after myocardial infarction in either the infarcted or non-infarcted regions of the heart

Question 11

Alterations in Ventricular Shape and Size Following Acute MI

Answer 11

Acute alterations in ventricular dimensions (seconds)
Infarct expansion (hours-weeks)
**Hypertrophy/dilation of noninfarcted segments (weeks-years)

Question 12

Eccentric Hypertrophy

Answer 12

Due to volume overload
Ventricular dilation and overall heart enlargement
Sarcomeres added in series

Question 13

Concentric Hypertrophy

Answer 13

Due to pressure overload
Ventricular wall thickening
Sarcomeres added in parallel

Question 14

Mechanisms of Post-MI Ventricular Remodeling

Answer 14

Cardiac myocyte hypertrophy
Cardiac fibroblast hyperplasia
Perivascular and interstital fibrosis
Vascular remodeling and angiogenesis
Cardiac myocyte apoptosis

Question 15

Rx of Ventricular Dysfunction

Answer 15

Early recognition of remodeling, because months/years of remodeling will eventually lead to CHF
Remodeling is growth-mediated response and derived from mechanical and local neurohormonal factors
PREVENTING or SLOWING the progression of ventricular remodeling will prevent/delay development of CHF

Question 16

Drugs that Prevent Ventricular Remodeling

Answer 16

ACE Inhibitors/ARBs/LCZ696
Beta Blockers
Aldosterone Antagonists

Question 17

Drugs the Prolong Survival with Ventricular Remodeling

Answer 17

ACE Inhibitors/ ARBs/LCZ696
Hydralazine and nitrates
Beta blockers (carvedilol, metoprolol, bucindolol)
Aldosterone antagonists (spironolactone, eplerenone)

Question 18

Clinical Manifestations of Left Sided Heart Failure

Answer 18

Symptoms: dyspnea, orthopnea, paroxysmal nocturnal dyspnea, cough, fatigue

Physical findings: diaphoresis, tachycardia, tachypnea, pulmonary rales, loud P2, S3 gallop (systolic dysfunction), S4 gallop (diastolic dysfunction)

Question 19

Clinical Manifestations of Right Sided Heart Failure

Answer 19

Symptoms: peripheral edema, RUQ discomfort

Physical findings: jugular venous distension, peripheral edema, hepatomegaly