Heart failure

Heart failure

Heart failure is a condition that can result from any structural or functional cardiac disorder that impairs the ability of the heart to fill with blood or pump a sufficient amount of blood through the body.

Heart failure is often undiagnosed due to a lack of a universally agreed definition and difficulties in diagnosis, particularly when the condition is considered “mild”. Even with the best therapy, heart failure is associated with an annual mortality of 10%. It is the leading cause of hospitalization in people older than 65.

Terminology

In some contexts, “heart failure” is considered equivalent to “congestive heart failure”. However, the latter term implies inadequate pumping of blood. [4] By contrast, in “high output heart failure”, cardiac function is actually normal or even supra-normal, but the demand of end-organs and other tissues outstrips what the heart can provide, occurring in the context of severe anemia, beriberi (vitamin B1/thiamine deficiency), thyrotoxicosis, Paget disease, arteriovenous fistulae or malformations, and inappropriate tachycardia.

“Congestive heart failure exacerbation” or “decompensated heart failure” (”DHF”) refer to episodes in which a patient with known chronic heart failure acutely develops symptoms.

There are several terms which are closely related to heart failure, and often are the cause of heart failure, but should not be confused with each other: asystole, cardiac arrest, ischemic cardiomyopathy (implying that the cause of heart failure is coronary artery disease) and dilated cardiomyopathy (which is a description of echocardiographic findings characteristic of heart failure but which does not suggest any specific etiology).

Symptoms

Symptoms are dependent on two factors. The first is based on the side of the heart, right or left, that is involved. The second factor is based on the type of failure, either diastolic or systolic. Symptoms and presentation may be indistinguishable making diagnosis impossible based on symptoms.

Left-sided failure

The most common symptoms are respiratory in nature. Failure of the left ventricle causes congestion of the pulmonary capillaries. The patient will have dyspnea (shortness of breath) on exertion (dyspnée d’effort) and in severe cases, dyspnea at rest. Easy fatigueability and exercise intolerance are also common complaints. Increasing breathlessness on reclining, called orthopnea, occurs. It is often measured in the number of pillows required to lie comfortably, and in severe cases, the patient may resort to sleeping while sitting up. Another symptoms of heart failure is paroxysmal nocturnal dyspnea, a sudden nighttime attack of severe breathlessness, usually several hours after going to sleep. If left ventricular function is extremely compromised, symptoms of poor systemic circulation become manifest, leading to dizziness, confusion and diaphoresis and cool extremities at rest.

Right-sided failure

The right side of the heart pumps blood returned from the tissues to the lungs, where CO2 is exchanged for O2. Right ventricular failure leads to congestion of systemic capillaries. This leads to peripheral edema or anasarca and nocturia (frequent nighttime urination when the fluid from the legs is returned to the bloodstream). In more severe cases, ascites (fluid accumulation in the abdominal cavity) and hepatomegaly (painful enlargement of the liver) may develop. Hepatic congestion may actually impair liver function, and jaundice and even coagulopathy may occur.

Heart failure (suboptimal left or right ventricular function) may decompensate easily. This most commonly results from an intercurrent illness (such as pneumonia), myocardial infarction (a heart attack), arrhythmias, uncontrolled hypertension, and patient non-compliance with diet or medication. Other classic precipitating factors are anaemia and hyperthyroidism. These place additional strain on the heart muscle, which may cause symptoms to rapidly worsen. Excessive fluid or salt intake (including intravenous fluids for unrelated indications, but more commonly from dietary indiscretion), and medication that causes fluid retention (such as NSAIDs and thiazolidinediones), may also precipitate decompensation.

Signs

Left-sided heart failure

Signs on physical exam indicating left ventricular failure are a laterally displaced apex beat (as the heart is enlarged) and a gallop rhythm (additional heart sounds) in case of decompensation. Heart murmurs may indicate the presence of valvular heart disease, either as a cause (e.g. aortic stenosis) or as a result (e.g. mitral regurgitation) of the heart failure.

Common respiratory signs are tachypnea and increased work of breathing (non-specific signs of respiratory distress), rales or crackles, which suggests the development of pulmonary edema, dullness of the lung fields to percussion and diminished breath sounds at the bases of the lung, which suggests the development of a pleural effusion (fluid collection in the pleural cavity) that is transudative in nature, and cyanosis which suggests hypoxemia, caused by the decreased rate of diffusion of oxygen from fluid-filled alveoli to the pulmonary capillaries.

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