Saturday, 1 February 2014

Q and A on Angina and Heart Attacks

The human heart pumps six litres of blood per minute around the body for an entire lifetime (and up to 18 litres per minute during exercise and pregnancy), maintaining the delivery of oxygen and nutrients to all body tissues. Three (and in some people, four) major coronary arteries (running on the surface of the heart) supply blood to the heart muscle and slowly narrow with age due to the accumulation of fat and inflammatory cells in the wall. This process known as atherosclerosis is accelerated by smoking, diabetes, high blood pressure and high cholesterol levels.

What is Angina?
As the arteries narrow beyond 60%, blood flow to the heart muscle is restricted during exercise and can produce symptoms of stable angina during physical activity. In most people, this is a central chest discomfort (described as a weight on the chest or a tight band across the chest) radiating to the shoulders and/or neck and associated with shortness of breath. Others may only experience breathlessness, jaw pain or upper back discomfort. These symptoms typically resolve with rest. Occasionally there may be no warning symptoms whatsoever.

What is a Heart Attack?
A complete blockage of a coronary artery results in a heart attack which is potentially fatal. Heart attacks are the most common cause of death in the developed world and the risk of death following a heart attack is 40% if untreated. The symptoms of a heart attack are the same as those described above but more severe and typically associated with sweating, feeling faint, vomiting and sometimes collapse. Interestingly, 25% of heart attacks do not produce any recognizable symptoms or are ‘silent’.

How do we treat Heart Attacks?
Thirty years ago, heart attack patients would spend at least two weeks in hospital and, with no specific treatment available, the probability of leaving hospital (having survived the initial attack) was only 80%. Over the last thirty years, ‘clot busting’ drugs improved survival rates to 90% but patients spent a week in hospital, often suffered significant muscle damage and often developed heart failure.

Now there is substantial evidence that the best treatment for heart attack patients is an emergency (or primary) coronary angioplasty delivered as quickly as possible. An interventional cardiologist, with the help of his or her team, performs an angiogram by passing a narrow plastic tube (called a catheter) into the circulation (through a small tube in the groin or wrist) and to the heart, obtaining detailed x-ray images of the coronary arteries. The artery responsible for the heart attack is then identified and reopened with a fine wire, balloon and a stent (a wire mesh tube to keep the artery open). Other devices to aspirate clot from the arteries may also be used in conjunction with drugs injected directly into the blocked artery. Survival rates are greater than 96% and patients leave hospital after two or three days with a lower risk of heart failure.

Heart attacks require emergency treatment and delays can result in death. At designated ‘24/7’ regional heart attack centres like Frimley Park NHS Foundation Trust, we have a ‘Door to Balloon’ target (namely, the time between the patient entering the hospital via ambulance or helicopter and having their blocked artery reopened) of 60 minutes (and in practise we average 40 minutes).

What should I do if I think I have Angina?
When symptoms are stable, in other words symptoms develop with activity but resolve with rest, urgent advice should be sought from your GP and then a cardiologist. Your cardiologist will arrange a treadmill test, an ultrasound study of your heart and possibly an angiogram before deciding on the best treatment for you. Symptoms developing at rest should be regarded as ‘unstable’ and treated as urgently as possible.

The ideal situation would be to avoid a heart problem altogether. Avoiding cigarettes, regular moderate exercise, weight control, blood pressure control and a healthy diet (in particular avoiding sugar and controlling fat intake) can help reduce your risk of developing heart problems. However a number of unidentified factors (including genetic factors) mean that no one is immune from heart disease and symptoms should always be taken seriously.

Vinod Achan
Vinod Achan is a Consultant Cardiologist and the Clinical Lead for Primary Angioplasty at the Surrey Heart, Stroke and Vascular Centre, Frimley Park Hospital NHS Foundation Trust. Frimley Park Hospital NHS Foundation Trust is an award winning 24/7 regional Heart Attack Centre, performing over 1000 coronary angioplasties a year and delivering emergency cardiac care to a population of one million people.
(Explanation of figure: A. Blocked coronary artery. B. Stent being deployed. C. Reopened coronary artery.)