Learning Center Articles

Heart Failure

Heart Failure

  • Complex clinical syndrome resulting in insufficient blood supply/oxygen to tissues and organs
    • Involves diastolic or systolic dysfunction
    • Ejection fraction (EF) is amount of blood pumped by LV with each heart beat
  • Associated with CVDs
  • Increase in incidence and prevalence
  • Most common cause for hospital admission in adults over age 65

Risk factors

  • Primary risk factors
    • Hypertension
      • Modifiable risk factor
      • Properly treated and managed, incidence of HF can be reduced by 50%
    • CAD
  • Co-morbidities contribute to development of HF

Etiology of Heart failure

  • Anything that interferes with mechanisms that regulate cardiac output (CO)
  • Primary causes
    • Conditions that directly damage the heart
      • Hypertension, including hypertensive crisis
      • Coronary artery disease, including myocardial infarction
      • Rheumatic heart disease
      • Congenital heart defects (e.g., ventricular septal defect)
      • Pulmonary hypertension
      • Cardiomyopathy (e.g., viral, postpartum, substance abuse)
      • Hyperthyroidism
      • Valvular disorders (e.g., mitral stenosis)
      • Myocarditis
  • Precipitating causes
    • Conditions that increase workload of ventricles

Cause

Mechanism

Anemia

Decrease O2-carrying capacity of the blood stimulating

Increase in CO to meet tissue demands, leading to increase in cardiac workload and increase in size of LV

Infection

Increased O2 demand of tissues, stimulating increase CO

Thyrotoxicosis

Changes the tissue metabolic rate, increased HR and workload of the heart

Hypothyroidism

Indirectly predisposes to increased atherosclerosis.

Severe hypothyroidism decreases myocardial contractility.

Dysrhythmias

May decreased CO and increased workload and O2 requirements of myocardial tissue

Bacterial endocarditis

Infection: increased metabolic demands and O2 requirements

Valvular dysfunction: causes stenosis or regurgitation

Obstructive sleep apnea

Frequent nighttime apnea results in increased afterload, intermittent hypoxia, and increased sympathetic nervous system activity.

Pulmonary embolism

Increased pulmonary pressure resulting from obstruction leads to pulmonary hypertension, decreased CO.

Paget’s disease

Increased workload of the heart by increased vascular bed in the skeletal muscle

Nutritional deficiencies

May decrease cardiac function by increased myocardial muscle mass and myocardial contractility

Hypervolemia

Increased preload causing volume overload on the RV