Kidney Failure Also Endangers The Heart

It has been known for a long time that people with diabetes have a much higher risk of a heart attack or a serious cardiac arrhythmia (abnormal heartbeat) than do people with normal metabolism. The Framingham study in the USA showed that in men this cardiac risk is 3.8 times higher and in women it is 3.5 times higher.

The risk is particularly high in people with diabetes who already have kidney damage. Many studies have shown that for people with Type 1 diabetes there is a significant increase in the frequency of heart attack, especially once macroalbuminuria is present.

For people with Type 2 diabetes, the risk is much higher from the start, but still increases further once micro- or macroalbuminuria becomes detectable. The main reason for this is that in these people, a host of risk factors for blocked arteries come together: diabetes, hypertension, lipid metabolism disorders and smoking all increase the chances of coronary artery disease.

In addition, narrowing or malfunction of the capillaries in the heart plays an important role, leading to disruption of heart muscle function. Many patients with nephropathy have suffered damage to their autonomic nervous system, which prevents regulation of the filtration pressure in the kidneys.

This also adversely affects the heart. It leads to an increased risk of cardiac arrhythmia and eventually atrial fibrillation. It has also been established that the blood platelets of people with diabetes are ‘stickier’ than those in other people.

Consequently, they form clots more readily; these can then stick to the walls of the coronary blood vessels, which have already been damaged by arteriosclerosis, to form plaques, leading to blockage of these vessels. Arteriosclerosis of the coronary arteries, which in the end results in a heart attack, is a slow process that often goes undetected for many years.

Is is therefore very important to pay attention to the first symptoms that indicate the heart muscle is not receiving sufficient oxygen because the blood vessels that supply the muscle have become blocked with plaque. The best known method of investigation is electrocardiography (ECG).

This is usually performed both when the person is at rest and after exercise. It detects changes in the circulation which can be interpreted by the doctor or nurse. If circulatory disturbances or alterations in the heartbeat are seen, further cardiological investigations must be undertaken, such as angiography.

This can reveal where the arteries are blocked. The constricted regions may be dilated again by balloon angioplasty or by insertion of a coronary stent. Sometimes, a heart bypass operation may be necessary.

Echocardiography is another very useful method of investigation, especially for patients with kidney failure and hypertension. This uses ultrasound to determine the state of the chambers in the heart, the heart muscle and the heart valves. It provides information concerning the burden on the cardiac muscle and its capability.

The echocardiogram can show whether the heart muscle has enlarged in response to the high blood pressure, a condition known as cardiac hypertrophy. This is a bad prognosis: the thickened heart muscle is particularly sensitive to circulatory disturbances, because it is poorly provided with oxygen but actually has a higher than normal need for oxygen.

The inner wall of the left ventricle (the main chamber in the heart) is the most sensitive, since it is poorly supplied with blood vessels but exerts the greatest pressure. The heart muscle here can die off continuously, totally undetected, and be replaced by connective tissue.

The ability of the heart to pump blood around the body fades gradually. This can be recognized early by echocardiography. One of the first noticeable symptoms for such changes is breathlessness during physical activity.

Examination by echocardiography should also be performed regularly for people with diabetic nephropathy. This provides information on the activity of the heart but also on the quality of the blood pressure management. If the thickness of the heart does not decrease, but continues to increase, then the blood-lowering treatment needs to be improved.

A special technique, called stress echocardiography, can nowadays give information on circulatory disturbances in the heart, which then indicate the need for further investigation. Echocardiography is an important method of examination for patients with pre-existing kidney failure.

These patients should avoid angiography because the contrast materials required for this technique are excreted via the kidneys and would impose an additional burden on these already overstressed organs.