Cardiovascular Diseases and Heart Failure

Heart Failure

• Heart failure is a general term used to describe impaired pumping ability of the heart, resulting in inadequate perfusion of tissues.
• ~1% of Americans over the age of 65 have heart failure.
• 20% of hospitalizations for patients 65 or older is due to heart failure.

Causes of Heart Failure

• Impaired cardiac function:
  • Myocardial disease (MI, cardiomyopathies, myocarditis)
  • Valvular heart disease (both stenotic and regurgitant disease can progress to failure)
• Excess work demands:
  • Increased pressure work (systemic hypertension, pulmonary hypertension, coarctation of aorta)
  • Increased volume work (arterio-venous shunts, excessive administration of IVF)
  • Increased perfusion work (anemia, thyrotoxicosis)

Left Sided Heart Failure

• Failure of left heart to move blood from the pulmonary circulation into the systemic circulation
• Leading to a decrease in cardiac output
• Increase in left atrial and left ventricular end-diastolic pressures
• Congestion in the pulmonary circulation
• Associated conditions:
  • Acute myocardial infarction
  • Stenosis or regurgitation of mitral/aortic valves
  • Rapid infusion of IVF or blood

Forward and Backward Effects of Left Heart Failure

• Forward effects:
  • Decreased systemic blood pressure
  • Fatigue
  • Increased heart rate
  • Decreased urine output
• Backward effects:
  • Increased pulmonary congestion (especially when lying down)
  • Dyspnea (difficulty breathing)
  • Right heart failure if condition worsens

Right Heart Failure

• Failure of right heart to pump blood forward into the pulmonary circulation
• Leading to accumulation or damming back of blood in the systemic venous side
• Increase in right atrial, RV end-diastolic, and systemic venous pressure
• Causes:
  • Conditions that restrict blood flow into lungs
  • Stenosis or regurgitation of tricuspid or pulmonic valves
  • Cardiomyopathy
  • Persistent left-sided failure
  • Acute or chronic pulmonary disease (pneumonia, pulmonary emboli, pulmonary hypertension)

Forward and Backward Effects of Right Heart Failure

• Forward effects:
  • Decreased pulmonary blood flow
  • Decreased blood oxygenation
  • Fatigue
  • Decreased systemic blood pressure (due to decreased left heart filling)
• Backward effects:
  • Increased venous pooling of blood
  • Edema of hands and feet
  • Ascites
  • Jugular vein distension
  • Hepatomegaly and splenomegaly

High Output Failure

• Despite adequate blood volume and normal or elevated myocardial contractility, the heart increases its output but the body's needs are still not met
• Causes:
  • Anemia (increases heart rate and stroke volume to increase O2 carrying capacity)
  • Sepsis (systemic vasodilation causes hypotension and increased heart workload)
  • Hyperthyroidism (increased thyroxine levels increase BMR)
  • Beriberi (thiamine deficiency, impairs cellular metabolism in tissues)