THERE is a rising prevalence of cardiovascular disease in developing countries, which is directly related to the westernisation of our lifestyle and consequent increase in disease risk factors such as hypertension, diabetes, high cholesterol, smoking, and obesity.

Current data reveal that up to 30 per cent of the Jamaican adult population is hypertensive, about 30 per cent of men and 60 per cent of women are overweight or obese, and up to 15 per cent have diabetes. This worrisome trend is set to continue for the foreseeable future as more adolescents are becoming obese and are therefore at increased risk for developing Type 2 diabetes and eventual coronary artery disease later in life.

UNDERSTANDING CARDIOVASCULAR DISEASE

An understanding of how cardiovascular disease occurs is important to understanding how radiologists aid in its detection. Simply put, risk factors such as high blood pressure, smoking, diabetes, high cholesterol, and obesity promote the damage of blood vessels and deposition of fatty deposits in their walls. This is known as atherosclerotic plaque formation.

This plaque causes narrowing of the arteries, which in turn reduces the amount of blood supplied by these arteries. As the blood supply decreases, the organs supplied by these arteries become ischemic. When the blood supply is eventually cut off, an infarction occurs.

When the heart is affected, symptoms progress from chest pain during physical activity to chest pain at rest — to a heart attack.

A heart attack simply means that blood supply to a part of the heart has stopped, which causes infarction of the wall of the heart. The heart is, therefore, unable to do its job of pumping blood around the body effectively and is said to be in failure.

HEART TESTS

There are many different types of heart tests which look at different aspects of heart function and morphology. Patients will be familiar with electrocardiogram (ECGs) in their various forms and echocardiograms. Radiologists are involved in the interpretation of heart tests including chest X-rays, nuclear medicine studies, and coronary computed tomography angiography (CTA), which is the test we will focus on in this article.

CORONARY COMPUTED TOMOGRAPHY ANGIOGRAM

A coronary computed tomography angiogram uses advanced CT technology along with IV contrast material to obtain high-quality images of the heart and great vessels. CTA is a non-invasive method for detecting blockages in the coronary arteries.

The following indications are used to select patients for CTA.

• Detection of Coronary artery disease (CAD) in symptomatic patients without known heart disease, either non-acute or acute presentations;

• Detection of CAD in patients with new onset or newly diagnosed clinical heart failure and no prior CAD;

• Preoperative coronary assessment prior to non-coronary cardiac surgery;

• Patients with prior electrocardiographic exercise testing: Normal test with continued symptoms or intermediate risk Duke treadmill score;

• Patients with prior stress imaging procedures: Discordant electrocardiographic exercise and imaging results or equivocal stress imaging results;

• Evaluation of new or worsening symptoms in the setting of a past normal stress imaging study;

• Risk assessment post-revascularisation: Symptomatic if post-coronary artery bypass grafting or asymptomatic with prior left main coronary stent of three millimetres or greater;

• Evaluation of cardiac structure and function in adult congenital heart disease;

• Evaluation of cardiac structure and function: Ventricular morphology and systolic function;

• Evaluation of cardiac structure and function: Intracardiac and extracardiac structures.

THE PATIENT

The patient who undergoes a CTA is generally a symptomatic patient who is at low or intermediate risk for coronary artery disease. Asymptomatic patients are not screened by this method because the radiation exposure is not justified. High-risk patients undergo invasive catheter coronary angiography because these patients will likely need to be stented (tubular structure is placed in the coronary artery to keep it open).

Patients should avoid caffeine and smoking 12 hours prior to the procedure to avoid cardiac stimulation. They should stop eating solid foods four hours before the study and increase fluid intake.

Patients should have good renal function and should not be allergic to the contrast, which is used during the test. Beta blockers and nitroglycerine are given to slow down the heart and dilate the coronary vessels, respectively. This ensures better images.

CTA is extremely sensitive for the detection of coronary artery pathology. This sensitivity decreases in patients with a lot of calcified plaque (high calcium score), but remains acceptable in most cases.

I am passionate about radiology because it allows the detection of disease processes at a stage where meaningful intervention can be instituted and a patient’s quality of life can be preserved. CTA is one such modality that can detect serious narrowing of the coronary vessels before they threaten the life of the patient. This allows for efficient selection of patients who will then go on to have catheter angiography and stenting.

As usual, my mantra remains teamwork between the referring doctors and the radiologist to ensure the best outcome for the patients.

These tests can be quite expensive, but the cost is nothing compared to the long-term costs associated with loss of productivity or rehabilitation. No price can be put on loss of life.

It is my hope that the day will come when the majority of Jamaicans will have access to some form of health insurance which will allow them to take advantage of the explosive technological advances occurring in medicine.

Prevention is still better than cure, and healthy lifestyle choices cannot be overstressed.

Dr Duane Chambers is a consultant radiologist and founding partner of Imaging and Intervention Associates located at shops 58 and 59 Kingston Mall, 8 Ocean Boulevard. He may be contacted through the office numbers 618-4346 or 967-7748.