Keeping heart failure at bay

Every time I tell a patient that he or she has heart failure their face falls as they envisage a cardiac arrest. “Doctor, did I get a cardiac arrest? Am I going to die?” they ask.

The heart pumps approximately five litres of blood around the body in a minute at rest and this increases to more than 18 litres per minute as the body becomes active and demands more oxygen, especially during exercise.

This cardiac reserve of 13 litres while the body is at rest is a hallmark of heart failure because as the efficiency of the pump declines the heart is unable to deliver this reserve.

In severe heart failure, the heart can fail to deliver even the minimum five litres a minute.

How common is heart failure?

It affects up to one to two of the adult population. The prevalence of heart failure in Kenya and the world is expected to increase in the coming decades because of an increase in the risk factors.

The symptoms of heart failure are shortness of breath, occurring with a lot of struggle.

Do you get short of breath when you climb stairs to the first floor or second-floor? This is also usually the first symptom of heart failure.

Put simply, heart failure refers to a condition where the heart cannot supply sufficient oxygen (through the blood) to the rest of the body.

So everything in the body is normal except for the pump. Therefore, when you try to make an effort to carry water, climb stairs, or jog the body gives up with severe panting and you eventually stop.

What follows shortness of breath is more dramatic and is a sign that the disease has progressed. This includes swelling of the feet, inability to sleep because the breathing gets worse, and sometimes you cannot complete a telephone conversation without stopping to breathe.

What causes heart failure?

· Elevated blood pressure, commonly referred to as hypertension. This is the most commonest cause. This accounts for more than half of all cases of heart failure. Hypertension causes extreme stress to the heart muscle that gets larger over time. As the heart enlarges then its efficiency as a pump falters and heart failure sets in.

· A heart muscle disease. These are situations where the heart muscle gets disease due to a genetic defect or an infection with subsequent dysfunction of the heart as a pump.

· Abnormal valve function (either narrowed or leaky heart valves), blocked or narrowed heart arteries, and heart rhythm problems that cause the heart to become weak. · Toxins. These are substances ingested or injected and affect the heart muscle. The two best examples are excessive alcohol intake that damages the heart muscles and chemotherapy agents (drugs used to treat cancer).

How is heart failure diagnosed?

The diagnosis of heart failure lies in the history of the symptoms, mainly the shortness of breath.

Heart failure commonly occurs in patients with hypertension, diabetes, elevated cholesterol, who smoke, are obese, and take alcohol in excess.

Any previous use of cancer drugs is also a risk. Other causes of shortness of breath should be considered; and these include lung diseases such as asthma, lung disease related to smoking and use of biofuel (chronic obstructive airway disease), and infections such as tuberculosis and pneumonia.

People who are acutely ill of heart failure usually have something that has caused them to get worse. This may be too much fluid accumulation as occurs in progressive heart failure, heart rhythm problems, or a heart attack.

When a heart attack occurs, the heart muscle is deprived of oxygen and the heart muscle dies. Within a short time, the contraction of the heart muscle is affected, and heart dysfunctions. The patient gets rapid shortness of breath and this has to be treated immediately as the patient may die if sufficient oxygen is not delivered to the body.

This sequence of events offers a good analogy of how patients die of heart failure. If the heart cannot get sufficient oxygen to sustain itself then cardiac arrest sets in and the patient dies.

The diagnosis of heart failure is done using a blood test known as brain natriuretic peptide (BNP). The more severe the symptoms of heart failure, the higher the level of BNP. This test is used to differentiate symptoms of heart failure from those of the respiratory system.

Another immediate test that is key in the diagnosis of heart failure is an electrocardiogram (ECG). This is an electrical recording of heart activity. It is available within three to five minutes and helps diagnose an acute heart attack and heart rhythm problems that can be treated quickly and prevent deterioration of heart function.

This is because an acute heart attack presents an opportunity to treat the blocked heart artery and prevent muscle injury and death.

The next most useful test in the diagnosis of heart failure is an echocardiogram. An echocardiogram is an ultrasound of the heart that shows how the heart muscle functions and tries to explain the cause of heart failure. The echocardiogram, for example, can show changes related to hypertension, heart muscle disease, valve dysfunction, and estimate the functioning capacity of the heart.

Most patients with heart failure have reduced contraction of the left ventricle but up to half may have a normal left ventricular function but significant heart failure symptoms brought about by abnormal relaxation of the left ventricle.

Other tests

Other tests are important and these evaluate complications caused by heart failure. These include kidney tests, blood count (to assess for anemia), thyroid function tests (hyper or hypothyroidism), and electrolytes.

Can heart failure be treated or does it signal early death? Advances in medicine in the last 30 years have given hope to heart failure patients. Heart failure killed more than 50 percent of its patients one year following diagnosis. This number has reduced to less than 20 percent with modern therapy.

Most medication is drug therapy that regulates heart function when the heart muscle is weak. These medicines are taken daily.

In addition to heart failure medication, the other risk factors must be addressed. These include blood pressure with medication and other lifestyle measures such as regular tolerated exercise and reduction in weight, cessation of smoking, treatment of elevated cholesterol, and cessation of alcohol. Blood glucose should also be controlled in patients with diabetes.

In addition to medication, there are complex devices (pacemakers) that are implanted in patients with heart failure that improve symptoms and prevent death. These devices can be implanted in Kenya.

Some heart failure patients require devices. These are called left ventricular assist devices. These patients who are candidates for left ventricular assist devices are also candidates for a heart transplant.

A heart transplant is a definitive treatment as these patients recover without any further requirement for drugs. However, patients require immunosuppression to prevent graft rejection. Can I be treated in Kenya? Kenya can treat all heart failure patients. All the medications recommended around the world are locally available. Complex heart devices are also available.

Dr Mzee Ngunga is a consultant interventional cardiologist at Aga Khan University Hospital.