Heart Failure: Causes, Symptoms, and Treatment Approaches

Understanding Heart Failure

Heart Failure (HF) is the inability of the heart to maintain adequate cardiac output to meet the patient's physiological needs.

Factors Influencing Cardiac Output

The primary factors influencing cardiac output are:

1. Distensibility: This is influenced by preload. An excessive increase in preload may be caused by conditions such as anemia, hyperthyroidism, or atrioventricular fistula.
2. Contractility: Often affected by conditions like myocardial infarction.
3. Afterload: Determined by the pressure in the aortic root.

Heart Failure Syndrome

The syndrome of heart failure is characterized by:

• Decreased Cardiac Output: Leading to lower blood pressure.
• Increased Secretion of Catecholamines: Which causes vasoconstriction, piloerection, sweating, pallor, and an increased heart rate. In the long run, excess catecholamines can produce myocardial damage.

Pathophysiology of Heart Failure

If cardiac output falls, such as during a myocardial infarction, pressure decreases, and the secretion of catecholamines increases. These catecholamines have the following effects:

1. Increases contractility, enhancing contractile strength like a tonic.
2. Increases heart rate.
3. Causes vasoconstriction, which increases blood pressure enough to supply the brain and heart. However, this has a negative side for the individual because afterload also increases.

In the long term, this sustained catecholamine activity causes necrosis or death of cardiac fibers, leading to a condition known as catecholamine cardiomyopathy.

Clinical Manifestations of Heart Failure

Feed-Forward Events

These events occur as a result of decreased cardiac output. Tachycardia occurs, increasing catecholamine levels, which causes:

• Fatigue
• Mottled cyanosis
• Oliguria
• Renal insufficiency
• Cardiogenic shock
• Central Nervous System (CNS) effects: mental dullness, confusion, asterixis, and Cheyne-Stokes respiration.

Backward Events

These are produced by increased venous pressure, which leads to increased hydrostatic pressure and the leakage of fluid into the pulmonary interstitium, causing dyspnea. In advanced stages, there can be:

• Pleural effusion
• Pulmonary edema
• Malnutrition
• Venous thrombosis

Hemodynamic Manifestations and Treatment

Hemodynamic manifestations include decreased contractility, increased afterload, and increased preload.

In the treatment of heart failure, beta-blockers are used. However, nowadays, Angiotensin-Converting Enzyme (ACE) inhibitors are considered among the best treatments due to their cardioprotective effects. Additionally, Aldactone (spironolactone), a drug that opposes cardiomyopathy and is derived from aldosterone, is also used.

Types of Heart Failure

Right-Sided Heart Failure

In right-sided heart failure, the right ventricle does not function properly, leading to an increase in right atrial pressure and vena cava pressure. This results in:

• Edema in the lower limbs
• Hepatic congestion, increased liver volume, and liver failure due to pressure from the inferior vena cava, which hampers liver drainage.

Left-Sided Heart Failure

Left-sided heart failure occurs due to a fault in the left ventricle, meaning blood is not adequately pumped to the aorta. This causes an increase in diastolic pressure, atrial, pulmonary vein, and capillary pressures, which produce pulmonary edema. Other common symptoms include:

• Dyspnea
• Orthopnea
• Paroxysmal nocturnal dyspnea
• Acute pulmonary edema