Heart Failure Overview

Left heart failure causes a backup of pressure in the pulmonary circulation, leading to increased fluid in the alveoli (pulmonary edema). This results in respiratory symptoms like shortness of breath, difficulty breathing when lying down (orthopnea), and sudden awakening with shortness of breath at night (paroxysmal nocturnal dyspnea).

Pulmonary capillary wedge pressure (PCWP) is a measure of pressure in the left atrium, which is directly related to the pressure in the pulmonary capillaries. In left heart failure, PCWP is high due to the backup of pressure in the left side of the heart.

If a question mentions normal PCWP, it indicates that there is no left heart failure.

Cardiogenic shock occurs when the heart muscle is too weak to pump enough blood to the body, leading to low blood pressure. This often happens with a high PCWP due to left heart failure.

Right heart failure causes a backup of pressure in the venous system, leading to symptoms like jugular venous distension (JVD) and peripheral edema.

Jugular venous distension (JVD) occurs when blood backs up into the neck veins due to right heart failure. Normal JVP is 3cm above the sternal angle, while JVD is higher than this.

Congestive heart failure (CHF) is a condition where both the left and right sides of the heart are failing. The most common cause of right heart failure is left heart failure.

Hepatosplenomegaly (enlarged liver and spleen) can be seen in right heart failure but is rarely mentioned on USMLE exams.

A congenital heart defect where there is a hole in the septum between the ventricles, allowing blood to flow from the left ventricle to the right ventricle.

A murmur that is heard throughout the entire cardiac cycle.

The murmur of a VSD can be softer at birth and louder at 7 days of life due to changes in pulmonary vascular resistance.

A VSD does not initially cause cyanosis. It develops years later due to pulmonary hypertension, right ventricular hypertrophy, and reversal of blood flow from right to left (Eisenmenger syndrome).

When a VSD is repaired, the left ventricular pressure increases, right ventricular pressure decreases, and left atrial pressure decreases.

If a VSD is present, oxygen levels in the right ventricle will be higher than in the right atrium.

A classic USMLE question involves a diagram showing oxygen levels in different heart chambers. A VSD is indicated if oxygen levels are higher in the right ventricle than the right atrium.

A VSD can be associated with tetralogy of Fallot, a complex congenital heart defect.

Low levels of Nitric Oxide synthase (NOS) are associated with Pulmonary Hypertension.

A loud P2 heart sound and tricuspid regurgitation are common clinical findings in cor pulmonale, which is a condition that involves right ventricular hypertrophy due to pulmonary hypertension.

Bilateral pitting edema, characterized by indentation that remains after pressure, is often caused by right heart failure. This is due to the inability of the right ventricle to pump effectively, leading to increased central venous pressure and fluid buildup in the legs.

Hypertension does not automatically cause peripheral edema due to increased pre-capillary resistance. In essence, constricted arterioles restrict blood flow through the capillaries, preventing excessive hydrostatic pressure and preventing fluid leakage.

Low albumin levels, often due to decreased hepatic production in cirrhosis, diminish intravascular oncotic pressure. This leads to fluid leakage from the vasculature into the tissues, resulting in lower extremity edema.

Proteinuria, leading to hypoalbuminemia, decreases intravascular oncotic pressure. This results in fluid leakage from the blood vessels into the surrounding tissues, causing peripheral edema.

Dihydropyridine calcium channel blockers, such as amlodipine and nifedipine, can cause peripheral edema as a side effect. This occurs due to their vasodilatory effects on peripheral blood vessels.

A strict vegetarian or vegan diet, lacking sufficient dietary protein, can lead to low albumin levels and lower intravascular oncotic pressure. This can result in fluid leakage and swelling in the lower extremities.

A type of non-bacterial thrombotic endocarditis (NBTE) seen in patients with malignancy. It's characterized by small, verrucous vegetations on both sides of the valve, caused by a hypercoagulable state.

A type of NBTE that occurs in individuals with systemic lupus erythematosus (SLE). It's caused by antiphospholipid antibodies, leading to small, verrucous vegetations on valve leaflets.

A common heart murmur characterized by a mid-systolic click, often asymptomatic.

Symptomatic MVP that presents with repeated episodes of fleeting chest pain on the left side, usually in young, otherwise healthy individuals. Often with a family history of MI.

The most common murmur, often asymptomatic, characterized by a mid-systolic click.

The first-line treatment for mitral stenosis, used if minimal valve calcification and pulmonary hypertension are present.

Treatment for mitral stenosis when balloon valvuloplasty fails or if severe stenosis, dyspnea, arrhythmia, or valve calcification are present.

A connective tissue degeneration leading to MVP, common in Marfan syndrome and Ehlers-Danlos syndrome.

A congenital heart defect where blood flow reverses from the right ventricle to the left ventricle through a ventricular septal defect (VSD), resulting in deoxygenated blood entering the systemic circulation. This leads to cyanosis and pulmonary hypertension.

Thebesian veins are small veins that drain blood from the myocardium and open into the chambers of the heart, including the left atrium. This can explain why the oxygen saturation may slightly decrease from the pulmonary circulation to the left atrium.

A ventricular septal defect (VSD) is a hole in the wall between the right and left ventricles. Repair is often indicated if complications arise such as pulmonary hypertension, right ventricular hypertrophy, arrhythmias, Eisenmenger syndrome, recurrent endocarditis, or aortic regurgitation.

A congenital heart defect where there is a hole between the atria and ventricles, often known as "endocardial cushion defect." This can also apply to ASD and VSD in patients with Down syndrome.

The most common cause of mitral regurgitation on USMLE exams is post-myocardial infarction (MI) papillary muscle rupture. This occurs when a heart attack damages the papillary muscles, which control the mitral valve, leading to leakage.

Mitral regurgitation can be a consequence of rheumatic heart disease, where inflammation and scarring of the valves can lead to valve dysfunction. This typically occurs years after the initial rheumatic fever episode.

Mitral regurgitation can occur due to general ischemia (lack of blood flow) or dilated cardiomyopathy (enlarged heart muscle). This leads to impaired valve function.

Aortic regurgitation (AR) is a condition where the aortic valve doesn't close properly, allowing blood to leak back into the left ventricle during diastole.

AR causes a bounding pulse because the blood rapidly leaves the aorta and flows back into the left ventricle during diastole, resulting in a large increase in systolic pressure and a quick drop in diastolic pressure.

A decrescendo holo-diastolic murmur, also known as a 'diastolic murmur loudest after S2', is a characteristic sound of AR. It is caused by the turbulent blood flow leaking back into the left ventricle.

Aortic dissection, a tear in the inner lining of the aorta, is a high-yield cause of AR on the USMLE. The dissection can propagate towards the aortic root, leading to aortic root dilation and AR.

Aortic regurgitation can lead to volume overload in the left ventricle, causing it to enlarge (eccentric hypertrophy) as it works harder to pump blood.

The most common cause of AR is aortic dissection, followed by MVP, but MVP rarely causes AR.

In Marfan and Ehlers-Danlos syndromes, aortic dissection is the most common cause of AR, even though MVP is more prevalent in these conditions.

Aortic valve replacement is considered when the patient has a reduced ejection fraction (EF), indicating impaired heart function.