Heart failure (Part two): Diagnosing and treating heart failure
Autore:Heart failure, whereby the heart cannot always pump enough blood around the body to keep up with all of the body’s needs can be quite scary, especially when a person feels like their heart is going to pop out of their chest or they start to find it difficult to breathe.
Expert cardiologist Dr Saqib Chowdary continues his double article series about heart failure, talking about how to diagnose heart failure and how this condition can be treated. He answers the question ‘What is heart failure?’ in part one.
How is heart failure diagnosed?
The initial diagnosis of heart failure is made after looking at a patient’s medical history which will include reviewing symptoms and risk factors (high blood pressure, coronary artery disease, diabetes or family history), as well as performing a physical examination for the signs of heart failure.
There are then a broad range of tests which may be ordered to confirm the diagnosis and identify potentially treatable underlying causes. These include:
- Blood tests
Levels of a chemical called N-terminal pro-B-type natriuretic peptide (NT-proBNP) can assist in the diagnosis of heart failure.
This looks broadly at the lungs and heart. It may also diagnose conditions other than heart failure that may explain signs and symptoms.
This test records the electrical activity of the heart through skin electrodes. It can diagnose heart rhythm problems (arrhythmias) and prior damage to the heart (e.g., significant heart attacks).
- Echocardiogram
An echocardiogram uses ultrasound (high frequency sound waves) to view heart structure and function in real time. It is painless and is the most commonly used test to identify weakness of heart contraction, dilation of heart chambers, abnormalities of the heart valves and thickening of heart muscle, all of which are the most common mechanisms of heart failure.
- Stress tests
Stress tests measure how well the heart responds to exertion. They are principally used to detect the presence of underlying artery disease. They consist of treadmill or bicycle exercises while attached to an ECG machine or echocardiogram, or may involve administration of a drug intravenously that stimulates the heart similar to exercise. Sometimes the stress test is done while wearing a mask to measure the ability of the heart and lungs to take in oxygen and breathe out carbon dioxide.
- Cardiac magnetic resonance imaging (MRI)
In a cardiac MRI, the patient lies within a tunnel that uses strong magnetic fields to create detailed images of the heart, including moving ones. It can be combined with injection of a tracer drug called gadolinium which can provide a great deal of information about the patterns of damage to heart muscle and therefore likely underlying causes.
- Cardiac computerized tomography (CT scan)
This is a doughnut-shaped X-ray machine that can produce detailed images of the heart and lungs. It can also produce pictures of the heart arteries in many cases.
- Coronary angiogram
This is the definitive test to look for narrowing and blockages in the heart arteries which supply blood to the heart muscle itself. A thin tube is advanced up through a blood vessel in the wrist all the way to the top of the heart and into each of the coronary arteries in turn. A dye, visible on X-ray is then injected while high resolution X-ray pictures are taken from several angles. This is done under local anaesthetic and patients can normally go home a few hours later.
How is heart failure treated?
Ideally the underlying cause of heart failure can be identified and treated. However, in most cases the damage has already been done and the residual heart failure is managed through the right balance of medications and, in some cases, the use of devices that help the heart contract properly.
Medications
The most common medications are listed below and are usually used as a combination of two or more drugs:
- Angiotensin-converting enzyme (ACE) inhibitors
Examples of these drugs are enalapril, lisinopril, perindopril and captopril. ACE inhibitors cause vasodilation (widening of blood vessels) and lowering of blood pressure. This can improve blood flow and decrease the workload on the heart. They have been proven to help patients with systolic heart failure live longer and feel better.
- Angiotensin-converting enzyme (ACE) inhibitors
Candesartan, losartan and valsartan are examples. These drugs work in a similar way to ACE inhibitors and are commonly used as an alternative for people who can't tolerate ACE inhibitors.
- Beta blockers
Examples of beta blockers are metoprolol, bisoprolol and carvedilol. These drugs slow the heart rate and lower blood pressure, thus limiting the amount of work the heart has to do. They can also suppress abnormal heart rhythms. They have been shown to both control heart failure symptoms and prolong life in heart failure patients.
- Diuretics
For example, furosemide and bumetanide. Commonly known as ‘water tablets’ they make you pass more urine and hence eliminate excess fluid, controlling the swelling that accumulates in some heart failure patients. This includes decreasing the fluid build-up in the lungs and enabling patients to breathe more easily. While they are very effective in controlling symptoms, they have not been shown to prolong life.
- Aldosterone antagonists
Spironolactone and eplerenone are examples of aldosterone antagonists. These are a special class of diuretics that prevent the loss of a salt called potassium in the urine. By blocking a hormone in the body called aldosterone, they have additional properties that can help people with severe systolic heart failure live longer.
- Digoxin
This is an older treatment for heart failure that slightly increases the strength of heart muscle contraction and also slows the heartbeat. It can control symptoms in systolic heart failure but is generally reserved for patients with an irregular heart rhythm known as atrial fibrillation.
Devices
There a number of pacemaker-like devices that are used in selected patients with systolic heart failure to improve symptoms and prolong life. These are implanted under the skin of the upper chest with wires running down a vein into the heart. These include implantable cardioverter-defibrillators (ICDs) which continuously monitor for dangerous heart rhythms that could cause the heart to stop beating effectively (cardiac arrest), to which patients with severe systolic heart failure are at increased risk. If this occurs, then the ICD will pace the heart or shock it back into normal rhythm.
In some patients with heart failure there is a problem with the heart's electrical system that causes the already-weak heart muscle to beat in an uncoordinated fashion. Cardiac resynchronization therapy (CRT), or “biventricular pacing”, uses another pacemaker-like device that sends timed electrical impulses to both of the heart's main pumping chambers (the left and right ventricles). This results in a more coordinated, and hence a more efficient pumping action. Often a biventricular pacemaker is combined with an ICD in the same device.
Heart transplant and ventricular assist devices
Replacing the failing heart with a healthy donor heart is a final option in some carefully selected patients with very severe heart failure that has not been helped by other treatments. This is not a viable option for all patients and the waiting list for donor hearts can be long.
A VAD, also known as a mechanical heart, is an implantable mechanical pump that helps pump blood from the lower chambers of the heart (the ventricles) out to the rest of the body. Usually implanted into the abdomen or chest, it is generally used to help keep heart transplant candidates alive until they get a donor heart. More recently they have been used as an alternative in patients who cannot have a transplantation.
Can heart failure be cured?
Occasionally finding and treating the underlying cause of heart failure, for example by fixing a defective heart valve, controlling fast heart rhythms or unblocking heart arteries may reverse or improve heart failure. However, in general heart failure cannot be cured, but it can be effectively managed by a specialist doctor directing the right combination of medication, devices and lifestyle measures.
Read part one of Dr Chowdary's double article series about heart failure, here.
Worried that you or someone you know might be at risk of heart failure? Schedule an appointment with Dr Saqib Chowdary as soon as you can.
