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Wednesday, November 23, 2011

Silent heart disease


Dr KK Aggarwal
Padma Shri and Dr B C Roy National Awardee
President, Heart Care Foundation of India


Sometimes back Late Shri K. R. Narayanan the Vice President of India went to Chennai to have his wife’s medical check-up and came back with his own bypass surgery. Many at that time were surprised after reading it. But is it not common?

A large number of cases with heart disease for the first time present with heart attack, sudden death or cardiomyopathy – a condition where the heart gets dilated. Many of these situations may need emergency therapeutic procedures including bypass surgery or balloon therapy.

Coronary artery disease (CAD) in which there is deposition of fat in the channels supplying blood to the heart is not a one day process. It takes on an average 10-50 years for the blockage to become significant to cause cardiac symptoms.

The process of fat deposition called atherosclerosis is multi factorial. Active or passive smoking, uncontrolled blood pressure or diabetes, stress, high cholesterol, stress (especially negative), obesity and lack of exercise are a few of the known risk factors. These risk factors must be present for long enough to cause the blockage.

In simple words it is said “you cannot gift, or accept as a gift, a heart attack”. You have to earn it i.e. you cannot get heart attack by smoking 100 cigarettes or not exercising or having you blood pressure or diabetes uncontrolled for a day.

Ten years to produce blockage of coronary arteries is long enough period for a person to get it checked up or for a doctor to detect it by way of investigations. But few are in the habit of getting a regular medical check up. We are very particular about our car, fridge, computer or cooler and will have it checked and serviced at regular intervals but not our body.

One must have a routine ECG done as a baseline at the age of 20. ECG may or may not diagnose underlying blockage and may be abnormal only at a time when the person is actually having cardiac pain. But the comparison with the base line ECG often helps in doubtful cases. In some cases the ECG abnormalities may be present even at rest.

The heart for its nutrition is dependent on oxygen and nutrients from the coronary arteries. The work the heart has to do on DEMAND is related to the oxygen and nutrition it will get on SUPPLY.

If the demand is more i.e. in situations like running, jogging, walking etc. the supply needed is more. And if the arteries are not being able to supply the required nutrition, as they are blocked, the heart will cry at the time of increased demand – called angina.

It takes at least 70% blockage of one or more of the arteries to cause symptoms of chest pain. Therefore the conditions may remain silent for a long period of time.

Before the person becomes symptomatic the evidence of blockage can easily be found by creating a situation of demand vs. supply imbalance – a test called as stress test or treadmill test (TMT). The person is subjected to graded exercise on a machine, while changes in heart rate, BP and the ECG is recorded, and also constantly monitored. The level of exercise when the person becomes symptomatic or the abnormal ECG changes suggestive of lack of blood supply appear indicates the severity of blockage, and further mode of treatment.

Normally a person without blockage should be able to do 12-14 minutes of graded exercises on the machine, achieving an exercise of about 10-12 METS i.e. about 10 times the basal energy expenditure, without causing any symptoms or ECG changes.

The TMT may be positive in the first 3 minutes of exercise, called severely positive, or in the 3-6 minutes of exercise, called moderately positive, or after 6 minutes or exercise called mildly positive TMT test.

Persons with moderately or severely positive TMT are often symptomatic, but the group with mildly positive TMT may be symptomatic or asymptomatic.

Silent heart disease is very common. The persons may have severe blockage of the coronary arteries and may suffer from episodes of damage to the heart muscles without experiencing any symptoms. Painless episodes are common amongst diabetics and patients with thyroid disorders.

Symptoms also depend on the duration of disease, age of the patient and the development of collaterals in the heart. If the person is old, there is enough time for the collaterals to develop and the person may do well on medicines. On the other hand if the person is young, the collaterals may not be adequate and he may end up with a heart attack.

Bypass surgery is necessary when there is failure of adequate medical treatment to provide the desired quality of life. Normally when the patient becomes symptomatic or for the first time he is detected to have underlying coronary disease, he is put on medical treatment first and if he does not respond he is considered for balloon or bypass surgery.

There are occasions when at the first detection of disease the patient may be subjected for surgery, for instance if the TMT test shows positive test (lack of blood supply) at 0-3 minutes of exercise or if angina occurs at low levels of heart rate or at rest or recurrent pain (3-4 times/day).

Angiography is often considered if the patient is young, has survived a recent cardiac arrest, has unstable angina or post heart attack angina or TMT is positive in the first stage.

If the angio shows disease of the main channel supplying blood to the heart it becomes an emergency surgery. Presence of 2 or 3 artery blockage in otherwise asymptomatic patient is not an indication for surgery. One has to correlate with the symptoms and response to the treatment.

Also a patient asymptomatic on drug with 2 or 3 vessel disease may not be subjected for surgery. Many a time an angina may temporarily become unstable due to some precipitating factors like blood loss, thyroid disorder, stress, fever etc. In such cases treating the precipitating factor may control the angina.

Indians have more severe heart disease. The blockage is more common, more severe and more diffuse. They also report late to the doctors. It is therefore expected that if we do not change our life style we may have the largest number of bypass surgeries in the world in time to come.

Bypass is not a cure. It only bypasses on already blocked artery. If the defective life style or risk factors continue either new blockage will appear in the non-bypassed vessels or in the grafts. The only answer is early detection of blockage and change in the life style.

Every person should have his TMT done once in 5 years after the age of 30 and annually if he has 1 or 2 risk factors, viz. family history of heart disease, high blood pressure, diabetes, smoking, obesity, stress, high cholesterol or a history of sudden death in the family.

Thanks for your VISITs

 
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