Cardiac Lecture: Heart Failure

Overview

• Heart failure occurs when the heart's pumping action becomes less powerful, decreasing contractile force.
• Result: Ineffective cardiac output leading to reduced tissue perfusion.
• Blood backs up in ventricles, increasing pressure and hydrostatic pressure, pushing fluid into tissues.

Statistics

• Approximately 5 million people in the U.S. diagnosed with heart failure; 500,000 new cases yearly.
• More common in African Americans and Hispanics.
• Major Cause: Hypertension.
• Death rate: 10% after one year; 50% within five years.
• Economic Impact: $60 billion annually, $23 billion inpatient.

Types of Heart Failure

Systolic vs. Diastolic

• Systolic Dysfunction:
  • Inadequate ventricular pumping, ejection fraction < 50%.
  • Causes: Coronary artery disease, diabetes, diabetic cardiomyopathy, alcoholic cardiomyopathy, valvular disease.
• Diastolic Dysfunction (Stiff Heart Syndrome):
  • Heart cannot fully relax during diastole, affecting filling.
  • Causes: High blood pressure, aortic stenosis, hypertensive cardiomyopathy, ischemic myocardial disease, coronary artery disease.

Categorization

• Left-Sided Heart Failure:
  • Causes: Hypertension, coronary artery disease, valvular disease.
• Right-Sided Heart Failure:
  • Causes: Left-sided heart failure, right ventricular myocardial infarctions, pulmonary hypertension.
  • Pulmonary problems (e.g., COPD) lead to right-sided heart failure.

Pathophysiology and Adaptations

• Cardiac myocytes inadequately adapt, increasing wall stretch to maintain cardiac output.
• Hypertrophy and Remodeling: Following myocardial injury, leading to excessive hemodynamic burden.
• Frank-Starling Mechanism: Increased preload to sustain cardiac performance.

Compensatory Mechanisms

• Neurohormonal Activation: Epinephrine, norepinephrine, vasopressin, vasoconstriction.
• Renin-Angiotensin-Aldosterone System: Increases aldosterone, sodium, water retention, raising preload.
• Endogenous Vasodilator Effects: Decrease over time; nitric oxide, prostaglandins, bradykinins.
• Sympathetic Response: Beta receptor stimulation increases heart rate, contractility.

Symptoms and Indicators

Left-Sided Heart Failure

• Symptoms often lung-related: Crackles in lungs, orthopnea (difficulty lying flat), pink frothy sputum (late sign), exertional dyspnea, paroxysmal nocturnal dyspnea.

Right-Sided Heart Failure

• Peripheral symptoms: Edema, jugular vein distension, weight gain.

Key Terms

• Core Pulmonale: Indicates right-sided failure due to pulmonary causes.
• Orthopnea: Inability to lie flat due to breathlessness.

Clinical Signs

• Crackles, orthopnea, pink frothy sputum, exertional dyspnea, paroxysmal nocturnal dyspnea.