Heart failure can be classified according to the affected chambers of the heart, the affected side of the heart, or whether it is acute or chronic.
Chronic vs. Acute
The terms chronic and acute relate to time rather than acuity. As heart failure develops over the course of many years it can be considered a chronic condition. Once heart failure has been diagnosed, episodes of decompensation (worsening signs and symptoms of heart failure) can occur frequently. These episodes of decompensation are often called acute, however, decompensated is the preferred term.
In a small percentage of cases, a sudden onset of heart failure signs and symptoms in a person with no history of heart failure with a previous normal cardiac function may also be called acute.
Left vs. Right
Right ventricular failure results in signs of inadequate peripheral circulation. Blood flow from the right to the left side of the heart is insufficient causing poor blood flow to the left ventricle. Left ventricular failure results in signs of pulmonary congestion/edema, and poor circulation to the vital organs and periphery.
Left-sided heart failure is more common than the right-sided failure and can be caused by abnormal systolic or diastolic action (see below). Left-sided heart failure can be further broken down into heart failure with reduced ejection fraction (HFrEF) or heart failure with preserved ejection fraction (HFpEF).
The following are common signs and symptoms associated with left-sided heart failure:
- respiratory symptoms: may include dyspnea, tachypnea, dyspnea on exertion, increased work of breathing, orthopnea, paroxysmal nocturnal dyspnea, wheezing, cough, pulmonary crackles, pleural effusion
- weakness, fatigue, decreased exercise tolerance
- changes in mental status that may include restlessness, insomnia, nightmares, memory loss, anxiety, agitation, paranoia, confusion
- diaphoresis, palpitations, tachycardia, S3, and S4, laterally displaced apical pulse, weight gain, pallor, cool extremities
Right-sided heart failure is most often a result of left-sided failure. When the right ventricle fails blood received cannot be pumped out effectively and backs up. This leads to congestion of systemic capillaries generating excess fluid accumulation, often in ankles, feet, legs and abdomen. Increased pulmonary pressure or lung disease can also cause right-sided heart failure.
The following are common signs and symptoms associated with right-sided heart failure:
- weight gain, peripheral edema, lower limb heaviness (usually, a substantial gain of extracellular fluid volume (ie, a minimum of 5 L in adults) must occur before peripheral edema develops)
- nocturia, diuresis at rest,
- ascites, abdominal distention, gastric distress, anorexia, nausea, constipation, hepatomegaly
- neck vein distention
- fatigue, shortness of breath
Heart Failure with Preserved Ejection Fraction (HFpEF)
Historically heart failure with a preserved or normal ejection fraction was referred to as diastolic heart failure as it was believed that there was diastolic dysfunction (inability to relax/stiffness). However, recent research indicates that this may not always be the case and other aspects of pathophysiology may contribute to symptoms. Diastolic heart failure is now referred to as HFpEF. HFpEF is less well understood than HFrEF.
HFpEF is a clinical syndrome characterized by clinical signs and symptoms of heart failure, normal EF (50%), and impaired diastolic function. HFpEF is almost always associated with co-morbidities including hypertension, coronary artery disease, diabetes, obesity, dyslipidemia, sleep apnea, lung disease, anemia and renal disease.
Patients with HFpEF tend to be older (>65 yrs), female, have a higher body mass index, more likely to be obese, and have a below normal hemoglobin level. Some studies indicate that there is also a higher incidence of atrial fibrillation but less coronary artery disease or valve disease than HFrEF patients.
During diastole, the myocardium relaxes and the ventricles stretch to allow the chambers to fill with blood. In patients with HFpEF, myocardial relaxation is impaired. This impacts the left ventricle's filling time and increases the chamber's stiffness. While the ejection fraction is preserved in HFpEF, systolic and myocardial function are abnormal. Below is a list of some of the causes of diastolic dysfunction.
Heart Failure with Reduced Ejection Fraction (HFrEF)
The more common type of heart failure, occurring in about 50 % of patients, is heart failure with a reduced ejection fraction, or HFrEF. With HFrEF, the left ventricle is dilated and enlarged with poor systolic function and an ejection fraction of less than 40%. The pump fails and is unable to contract sufficiently to circulate required blood to organs and tissues.
HFrEF can occur following myocardial infarction when ventricular tissue death reduces the heart's pumping efficiency. HFrEF can also be caused by prolonged stress on the heart from hypertension, valve disease, dysrhythmias, coronary artery disease, or damage to the ventricular wall.