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