Charles E. Denbow

This week's special guest columnist is Professor Charles E. Denbow. This is the second of his four-part series on various tests used to investigate problems in the heart. Part one appeared on November 15.

THE TWO-DIMENSIONAL ECHOCARDIOGRAM ( 2-D ECHO)

Echocardiography involves the use of pulsed reflected ultrasound waves (emitted from a probe placed on the surface of the chest) to produce an image of the heart and blood vessels. This enables the cardiologist to diagnose with great accuracy and reliability a wide variety of cardiovascular conditions.

Development of this diagnostic technique began internationally in the 1960s and 1970s, and it was introduced into Jamaica in 1981 by Drs. Sinda Dianzumba, Edward Chung and the author at the University of the West Indies. A major advantage of echocardiography is the fact that it is 'non-invasive', and hence does not involve the risk attendant upon the introduction of needles, tubes and sheaths directly into the cardiovascular system. In addition, it is available at a relatively low cost, and may be easily repeated thus facilitating serial studies whereby disease progression may be monitored or the response to therapeutic intervention assessed.

Echocardiography has revolutionised the diagnosis of cardiovascular disease over the last 25 years, and may also at this time be considered a ' bread and butter' cardiac investigation. This technique allows the cardiologist to assess the structure and function of the cardiac valves; the structure and function of the right and left ventricles( pumping chambers); the presence of heart muscle damage or scarring (from a 'heart attack'); the presence of fluid in the sac surrounding the heart (pericardial effusion); and the presence of blood clots (thrombi) or tumours (growths) within the heart.

AVAILABILITY

Echocardiography is available in several public and private institutions.

AMBULATORY ECG (HOLTER MONITOR)

This investigation was introduced because of the realisation that changes in a patient's cardiac rhythm may often be intermittent and hence easily missed by the ordinary routine electrocardiogram (ECG). This is so because the latter test only records the patient's cardiac rhythm (heartbeat) during the short period (often only a few seconds) when the patient is attached to the ECG machine.

Ambulatory electrocardiography may involve the use of an event recorder whereby the patient is connected to a small transistor radio-sized device and is instructed to trigger a recording of the heartbeat by activating a button at the time of any suspicious symptoms. The machine will then record the heart rhythm on tape at that instance thus allowing the observer to determine if a change in cardiac rhythm had in fact occurred.

The event recorder was introduced in Jamaica by the author in 1983, but has now largely been superseded by the Holter monitor. In the latter investigation, the patient's cardiac rhythm is recorded on tape for a full period of approximately 24 hours after which the removal of the recording device is followed by a computerised analysis of the patient's cardiac rhythm throughout the entire period by replaying the tape.

The patients are usually provided with a diary in which the time and nature of any symptoms are to be noted and attempts are made to correlate these symptoms with any observed changes in the cardiac rhythm.

This attempted correlation may be significant in a positive way ( where symptoms can be shown to be due to a rhythm change) or in a negative way (where the cardiac rhythm can be seen to be normal when symptoms are present.)

AVAILABILITY

(1) Cardiology Unit - University Hospital

(2) Heart Institute of the Caribbean

COST CODE in $JA

CHEAP - Less than $2000

INEXPENSIVE - $2,001 to $20,000

EXPENSIVE - $20,001 to $100,000

VERY EXPENSIVE more than $100,000

Charles E. Denbow is Professor of Medicine and consultant cardiologist at the University of the West Indies (Mona).