Heart Failure

The right side of the heart pumps blood to the lungs (pulmonary circulation), and the left side of the heart pumps blood to the rest of the body (systemic circulation). If one side of the heart, or indeed both sides of the heart, does not pump effectively, it is called heart failure.

Left sided heart failure
If the left side of the heart does not pump effectively to the organs, then this causes blood to accumulate in the veins and capillaries of the pulmonary circulation. This causes the pulmonary veins and capillaries to become engorged with blood. As the volume of blood is increased inside the vessels, this subsequently causes the pressure inside the vessels to be increased. If the pressure is high enough, then fluid will be forced out of the small capillaries covering the alveoli. This fluid then fills the alveoli. This is a condition called pulmonary edema.

Fluid in the alveoli causes a decrease in the space available for air. A decreased air space causes decreased gas exchange between the alveoli and capillaries. Therefore, the patient will appear short of breath. They may have an increased respiratory rate (tachypnea), difficulty breathing (dyspnea), increased effort (using accessory muscles) and decreased oxygen saturation.

The most common causes of left sided heart failure are coronary artery disease and hypertension. Other causes include cardiac arrhythmias, valve disease, myocarditis, pericardial effusion, anemia and volume overload. Heart failure on the left side usually progresses to cause failure on the right side too.

Right sided heart failure
If the right side of the heart does not pump effectively to the lungs, then this causes blood to accumulate in the veins and capillaries of the systemic circulation. This causes the systemic veins and capillaries to become engorged with blood. As the volume of blood is increased inside the vessels, this subsequently causes the pressure inside the vessels to be increased. If the pressure is high enough, then fluid will be forced out of the small capillaries in the organs and tissues. This can cause:

• Swelling of the feet and lower legs (peripheral edema)
• Enlarged liver (hepatomegaly) and enlarged spleen (speenomegaly)
• Fluid in the abdomen (ascites)
• Fluid in the pleural space (pleural effusion)
• Bulging neck veins (distended jugular veins)

Right sided heart failure is most frequently a consequence of left sided heart failure. These patients will have signs and symptoms of both right and left sided heart failure. Less commonly right sided heart failure can occur alone. Causes of isolated right sided heart failure include severe pulmonary disease, right sided myocardial infarction and right sided valve disease.

Investigations
Physical examination involves examining the patient for all the signs mentioned already, such as peripheral edema and distended neck veins.

Chest x-ray should be examined for evidence of pulmonary vascular congestion and pulmonary edema.

The size of the heart should be assessed on the chest x-ray. Often in chronic heart failure, the myocardium increases in size, in an attempt to pump more effectively. This however becomes counterproductive, and results in worsening heart failure. An enlarged heart is called cardiomegaly. 

Auscultation of the lungs should be performed to examine for evidence of pulmonary edema. Pulmonary edema causes crackles. The sound of crackles is the fluid bursting in the alveoli as air enters it. Therefore, the crackle sound is usually heard when the patient breathes in. Due to the forces of gravity, the crackles are heard in the bases of the lungs in the upright patient.

Auscultation of the heart should be performed to examine for evidence of an extra heart sound (called a third heart sound); however, this is not always present.

Routine blood tests include haemoglobin count (anemia can cause or exacerbate heart failure) and electrolyte levels (especially sodium). Renal function and liver function blood tests are also useful.

Electrocardiogram (ECG) should be performed to examine for arrhythmias or myocardial infarction, which are both potential causes of heart failure.

An echocardiogram (ECHO) can be performed to examine the size of the chambers in the heart. An ECHO can also measure the hearts ability to pump the blood out, called the ejection fraction. An ECHO can also identify any valve abnormalities, which is also a potential cause of heart failure.

Treatment
The underlying cause need to be identified and treated, for example coronary artery disease, hypertension or cardiac arrhythmias.

Oxygen should be administered to any patient that is breathless.

Diuretics (such as furosemide) are usually required. These increase the patient’s urine output, and therefore reduce the circulating blood volume. Having a lower circulating blood volume reduces the pressure in the vessels, and also enables the heart to
pump more effectively. 

Other medications that may be required include:•  

• angiotensin converting enzyme (ACE) inhibitor (such as lisinopril)•
• beta blocker (such as metoprolol), however very small doses should be used, and should not be commenced in severe or acute heart failure
• oral hydralazine together with isosorbide dinitrate, however not to be given if hypotensive
•  digoxin

An inotrope infusion (such as dopamine) may be required for patients who are hypotensive, or for patients who have significant pulmonary edema despite the above treatment.

Advanced Management
Vasodilator therapy reduces the pressure inside the vessel, and also enables the heart to pump more effectively. Vasodilator therapy can be administered as an intravenous infusion, and titrated according to the response and blood pressure. Examples of intravenous infusions commonly administered are nitroglycerin or nitroprusside.

Dobutamine is an effective inotrope in heart failure, as it increases cardiac contractility and cardiac output, and is less prone to causing hypertension when compared to dopamine. Furthermore, dobutamine causes some degree of vasodilation, making it the preferred inotrope for heart failure.