(1) Congestive heart failure (CHF) - systolic, diastolic, left side, right side, & symptoms

Heart Failure Overview

  • Definition: Heart failure occurs when the heart cannot supply enough blood to meet the body's demands.

  • Types:

    • Systolic Heart Failure: Inability of the heart's ventricles to pump blood effectively during systole.

    • Diastolic Heart Failure: Inability of the heart to fill adequately during diastole.

  • Congestive Heart Failure (CHF): Resulting condition due to blood backing up into the lungs, causing congestion/fluid buildup.

Prevalence and Causes

  • Common Condition: Affects millions globally and can lead to death due to insufficient blood supply to meet the body’s needs.

  • Causes of Heart Failure:

    • Various heart diseases (e.g., ischemia, valvular disease) impair the heart's pumping ability over time.

Systolic Heart Failure

  • Concept: The heart must achieve a certain cardiac output (CO), calculated as:

    • Cardiac Output = Heart Rate (HR) × Stroke Volume (SV)

  • Example Calculation:

    • If HR = 70 bpm and SV = 70 ml, then CO = 4900 ml/min (almost 5 liters/min).

  • Ejection Fraction:

    • Defined as the volume of blood ejected from the ventricle with each heartbeat relative to total volume:

    • Ejection Fraction = Stroke Volume / Total Volume

    • A normal range is 50-70%. Less than 40% indicates systolic heart failure.

    • Example: If total volume is 110 ml but only 44 ml is pumped out, then EF = 44 ml/110 ml = 40%.

Diastolic Heart Failure

  • Concept: Heart is pumping adequately, but ventricles are not filling sufficiently; normal ejection fraction.

  • Preload: Refers to the volume of blood in the ventricle before contraction, relevant to heart filling.

  • Example Calculation:

    • If total volume is 69 ml and stroke volume is 44 ml, EF = 44 ml / 69 ml = 64%.

  • Frank-Starling Mechanism: Shows that increased preload enhances contraction force.

    • Similar to stretching a rubber band to enhance snap back.

Types of Heart Failure

  • Left-Sided Heart Failure: Often due to systolic dysfunction; common causes include:

    • Ischemic heart disease (coronary artery atherosclerosis).

    • Long-standing hypertension leads to left ventricle hypertrophy, increasing oxygen demand.

    • Dilated cardiomyopathy can cause systolic left-sided heart failure by thinning muscle wall.

  • Diastolic Dysfunction in Left-Sided Heart Failure:

    • Often results from concentric hypertrophy due to prolonged hypertension, limiting ventricular filling.

    • Causes include aortic stenosis and hypertrophic cardiomyopathy.

Right-Sided Heart Failure

  • Causes: Often secondary to left-sided failure due to increased pulmonary pressure.

    • Isolated right-sided heart failure can occur due to cardiac shunts or chronic lung disease (cor pulmonale).

  • Manifestations:

    • Jugular Venous Distention: Due to fluid backup into systemic circulation.

    • Hepatosplenomegaly: Enlargement of liver and spleen due to fluid congestion.

    • Ascites: Fluid buildup in the peritoneal cavity.

    • Pitting Edema: Swelling in the legs due to fluid in interstitial space.

Diagnosis and Symptoms

  • Symptoms: Include dyspnea, orthopnea, and pulmonary edema leading to crackles (rales) on auscultation.

  • Heart Failure Cells: Hemosiderin-laden macrophages formed from red blood cell breakdown in alveoli due to fluid buildup.

Treatment Options

  • Medications:

    • ACE inhibitors to dilate blood vessels.

    • Diuretics to reduce fluid buildup.

  • Arrhythmias: Often accompany heart failure, reducing pumping ability.

  • Therapies:

    • Cardiac resynchronization therapy pacemakers for improved ventricular contraction.

    • Ventricular Assist Devices (VADs) to support heart function.

  • End-Stage Treatments: Heart transplants may be required if other treatments fail.