This is used to treat either patients requiring grafts to bypass narrowings in coronary arteries, or valve surgery, or both. Please read the section on heart valves first. If surgery is considered as the definitive treatment for valvular disease, certain points need to be borne in mind.
First, the timing of surgery is crucial. Patients may have their valvular conditions monitored by echocardiography for years before surgery is indicated. But certainly, any development of symptoms such as breathlessness or dizziness etc.
Certainly if symptoms were to develop before the next review date, then an earlier appointment should be expedited. For arterial grafts, please see the section on “Coronary Artery Disease” first.
With any valvular condition, exposure to blood borne infection is detrimental. Blood infections tend to target narrow or leaky valves in particular. This can result in endocarditis, where the valve can become destroyed with adverse clinical consequences.
Extra care needs to be taken in patients having valve surgery as artificial valves are particularly susceptible to infection. Before any valve surgery, full dental assessment is thus mandatory.
Prior to surgical consideration, some type of surgical risk assessment is made. The surgeon would discuss whether any other co-existing medical conditions would contribute to the risk of the procedure. Hopefully this does not apply, and the benefit of the procedure would outweigh the risk.!
Procedure is usually undertaken to treat coronary artery narrowings surgically. In order to restore blood flow around narrowings, usually angioplasty using stents is the first consideration as a treatment strategy as it is less intrusive. However, if there are several narrowings (especially if there are narrowing affecting the three main vessels), or the specific location of a narrowing is unsuitable, then surgery is considered. In this procedure, veins from the legs are harvested at the beginning of the procedure, and applied to the heart. These graft will ‘bypass’ the narrowing by attaching to the aorta at one end and attaching to the artery just beyond the narrowing. (See picture). These are referred to as vein grafts. For the most important artery that needs grafting, the left breast artery is used and diverted a short distance from the breast, to the front of the heart. This does not affect the breast at all.
The actual surgical procedure involves 5-10 days in hospital. During the operation which lasts a couple of hours, the circulation of the heart is “bypassed” by an artificial pump to substitute the hearts function. The heart can then be safely stopped and the grafts attached. The artificial pump can then be disconnected and the heart restarted. There are newer techniques that have been developed that allow for surgery to be performed on the beating heart . In addition, in most cases the chest is opened to perform the operation (hence the term open heart surgery), which will leave a scar on the front of the chest. In specific cases some operations can be performed without a major midline incision of the chest, but through a series of min-cuts. The advantage of this technique is that the recovery after surgery is much quicker. This option would be discussed with you.
Clearly this is a major operation, but these days the risks are much lower (2%). After surgery, patients are mobilised within 2 days, and go home around 5-7 days. Normal complications of the procedure include postoperative infections, and small collections of fluid. Generally, the healthier the patient pre-surgery, the less the complications afterwards. That’s why patients should have stopped smoking, lost weight and optimised their blood pressures and diabetes beforehand.
This covers a large number of conditions resulting in reduced heart pumping, and can be classified in many ways. If symptoms are sudden in onset, it is termed acute heart failure. If more progressive, it is termed as chronic heart failure. Most commonly when the heart’s ability to pump is affected, it is called systolic failure. Less commonly if the heart’s ability to relax and fill is affected it is termed diastolic failure (see below). Heart failure can present in many ways, but principally heralded by the onset of breathlessness on exertion. As the pump becomes less effective, the circulation is reduced causing increasing fatigue and reduced ability to exercise.
The causes of heart failure are numerous. They can be divided into those involving the loss or impediment of muscle function, electrical abnormalities affecting effective muscle pumping (see under electrical abnormalities), and valvular conditions resulting in either pressure or volume overload of the pump (see under Valvular conditions).
Myocardial Infarction (heart attack)
This is also discussed earlier, but is the commonest cause of heart failure. In this case the permanent loss of a section of heart muscle will reduce heart function. This can be assessed with echocardiography that can measure heart function directly, and is expressed as left ventricular ejection fraction. Normally, ejection fraction is between 55-70%. Echocardiography can help identify the specific area of muscle damage. With an acute myocardial infarction, breathlessness is sudden and if enough damage has occurred, then the diagnosis is of acute heart failure.
Apart from acute heart failure, a heart attack may not cause sudden loss of heart muscle function, but progressive changes. This is because after the loss of a section of heart muscle, the heart adapts by enlarging reactively. In the short term this bolsters heart function, but after a period of time (weeks to months) causes heart function to weaken and cause progressive heart failure.
This is when a significant area of heart muscle becomes inflamed and dysfunctional. This usually secondary to a viral infection and is not that common. However it can affect people of any age. It can be self limiting and cure itself. However it can occasionally be progressive and cause permanent changes and heart failure.
Cardiomyopathy is a broad term to cover a wide spectrum of conditions affecting heart muscle specifically. Dilated cardiomyopathy (DCM) occurs when the heart becomes enlarged in response to an insult to the muscle cells. It can be acute and reversible as with viral myocarditis. It can also be acute if the muscle is inflamed with progressive alcohol exposure (alcohol cardiomyopathy). This is surprisingly common, and can be reversed in earlier stages of the condition.
In more chronic cases, dilated cardiomyopathy can occur after previous myocardial infarction. Less commonly, but increasingly recognised is a familial dilated cardiomyopathy. This is an inherited condition and very important to identify. It can present before any symptoms of heart failure, usually when a chest X ray might have been performed incidentally for other reasons, and the heart was noted to be enlarged. In this condition, heart failure develops for no particular reason. In such cases, the relevance is that other family members need to be screened for the condition before it becomes a problem. Another rare but important cause of heart failure is peri-partum cardiomyopathy. As the name suggests, this occurs in response to giving birth, and should be considered in any new mother complaining of increasing breathlessness.
This includes restrictive cardiomyopathy, where the muscle becomes infiltrated with other pathological substances, or damaged by toxins or drugs. Hypertrophic cardiomyopathy where the there is abnormal thickening of heart muscle is discussed separately.
Diagnosis of Heart Failure
Heart failure is usually suspected in patients who have developed breathlessness. Patients often complain of swelling in the ankles. Cardiac failure is often suspected in cases of leg swelling. It should be born in mind that leg swelling can be due to many other causes (see under Symptoms). Sometimes a cardiomyopathy may be suggested by a routine chest X-ray performed for other reasons, and the heart found to be enlarged. Often I would have to say, that an apparently enlarged heart on the X ray in the absence of symptoms is usually a shadow projection issue, and not truly an enlarged heart, but it is worth checking it out.
An ECG is essential, although it can be normal. Prior to performing an echocardiogram, primary care doctors may perform a blood test to measure a body chemical called B-derived naturetic peptide (B-NP) that is elevated in heart failure. The main investigation in heart failure is the echocardiogram. This can confirm the diagnosis of heart failure and sometimes indicate the underlying cause. In addition it can detect the presence of diastolic failure. In this case, the heart is usually of normal size but the patient may be breathless. The failure is due to a loss of heart muscle elasticity. More recently cardiac MRI has become an established means of diagnosing the cause of heart failure. In a fair few patients cardiac catheterization is performed if underlying coronary disease is suspected.
Treating Heart Failure
Initial investigations such as cardiac catheterization may reveal the underlying cause, and suggest treatment. Otherwise, diuretics are initially prescribed to treat breathlessness. The main drug that impacts on prognosis are a family of drugs called ACE inhibitors (see under Drugs). These drugs act to lower the pressure in the heart and arterial circulation, and reduce the work the heart has to do. In recent years another class of tablets called beta-blockers have been used. These drugs also impact on prognosis too. They take up to a month before patients may feel symptomatic relief. They act on the principle that lowering the heart rate may improve the efficiency of heart function. Occasionally beta blockers may worsen heart failure symptoms. The other main medication that is used in heart failure is spironolactone (or eplerenone), which improves symptoms.
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