Heart Failure (HF)
Heart failure (HF) refers to any abnormality of function or structure in which there is a reduced ability for the ventricle to fill with or eject blood, resulting in impairment of cardiac output. The categories of heart failure are based on a measurement that signifies the efficiency with which the left ventricle ejects blood, called the left ventricular ejection fraction (LVEF). As a percentage, the LVEF is designated as
- Systolic Heart Failure (LVEF ≤ 40%): HF with reduced ejection fraction (HFrEF)
- Diastolic Heart Failure (LVEF >50%): HF with preserved ejection fraction (HFpEF)
Ventricular contractility and its resulting ejection force of its volume depend on the blood that fills the ventricle (“preload”), the contractility stimulation from cardiac fiber stretch, and the resistance from the aorta and stress from the ventricular walls (“afterload”). Thus, ventricular function is in a 3-way relationship among preload, contractility, and afterload. The net result of quality failure in any of these components results in decreased ejection fraction (heart failure) of the left ventricle.
Causes of Heart Failure
Left ventricular hypertrophy is a prominent condition of HF, regardless of whether it emerges as a complication of coronary artery disease, hypertension, diabetes, or valve disease. Causes of heart failure in order of importance:
- Coronary heart disease
- Cigarette smoking
- Valvular heart disease
- Conditions in which the diagnosis is not identifiable
Signs and Symptoms
As HF progresses, the symptoms emerge and worsen dyspnea, fatigue, and exertion intolerance. In advanced HF, walking only one city block, dressing, bathing, and other activities of daily living become difficult. Exercise intolerance increases. Edema from overload can present as pulmonary congestion, peripheral edema, and elevated jugular vein pressure. Renal function can decline.
Complications of Heart Failure
HF is a progressive condition, and eventually patients can have dyspnea at rest. Activities of daily living become impossible. Weight loss and hypotension are signs of advanced HF.
Acute Decompensated Heart Failure (ADHF)
There is a continuum for HF, and when a threshold of compensation is breached, the condition can become life-threatening and portend poorly for survival. In ADHF, the progression from chronic symptoms to acute emergent conditions is accompanied by hypotension, which is commensurate with hypoperfusion of blood, i.e., decreased oxygenation of tissue and subsequent end-organ compromise and/or failure:
- Dyspnea at rest
- Acute coronary syndrome
- Electrolyte disturbances
- Renal failure
HF is approached from a functional standpoint: diuretics, control of blood pressure, medical therapy, mechanical circulatory support (left ventricular assist devices–LVADs), heart transplant, and if treatment fails to the point of end-stage disease, palliative care.
The morbidity from HFpEF and HFrEF is about the same. Mortality rate, annually, is 5%, which is low, considering the pathology. Nevertheless, attempts to lower this percentage by reducing risk factors and comorbidities are important steps in prevention of advanced heart failure.