Biomedical subjects
Publications and source records attributed to B L Chia.
The simultaneous occurrence of left bundle branch block and right axis deviation is very rare and occurs mainly in patients with cardiomyopathy. This paper describes a 61-year-old man with end stage ischaemic heart disease who presented with this unique electrocardiographic abnormality.
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Right-sided chest lead ECGs (V3R to V6R) were recorded in 110 normal male subjects who were between the ages of 17 and 22 years old (mean, 17.9 years). The prevalence of the rS pattern decreased from V3R (89 percent) to V6R (37 percent). However, the opposite was the case for the rSr pattern (10 percent in V3R and 36 percent in V6R). The amplitudes of the r wave, S wave and secondary r wave all progressively decreased from V3R to V6R. The prevalence of the qr and qS patterns was 0 and 1 percent, respectively in V3R and 14 and 2 percent, respectively in V6R. A positive ST segment deviation of 0.5 to 1 mm was present in 13 percent of subjects in V3R and 5 percent in V4R. T wave inversion was common and the prevalence increased from V3R (60 percent) to V6R (79 percent).
Between December 1980 and December 1987, approximately 6,000 two-dimensional echocardiographic examinations were performed in our noninvasive cardiac laboratory. During this period, five cases of intra-atrial smoke-like echoes were diagnosed. The four patients with dense smoke-like echoes in the left atria all had echocardiographic evidence of severe mitral stenosis and thrombi in the left atrial cavity, both of which were confirmed at open-heart surgery. One patient with right-sided cardiomyopathy had echocardiographic evidence of dense smoke-like echoes and thrombus in the right atrial cavity. One of our five patients was receiving anticoagulant therapy, and none had a history of thromboembolism. We conclude that using conventional two-dimensional echocardiographic techniques, smoke-like echoes in the atria are a very infrequent finding and are very commonly associated with formation of thrombi.
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A 50-year-old male was admitted to hospital for repeated episodes of chest pain due to unstable angina. Serial electrocardiograms were all normal except for one electrocardiogram, recorded during chest pain, which showed isolated U wave inversion in leads I, V4 and V5. Subsequently, selective coronary arteriography showed isolated 99% stenosis of his left main coronary artery.
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Electrocardiograms from 204 subjects aged 60 and above, residing in homes for the aged, were analysed. 13% had evidence of cardiovascular disease. 55% of the electrocardiograms showed at least one abnormality. At least 10% of electrocardiograms showed left atrial hypertrophy, first degree atrioventricular block, right bundle branch block, pathologic Q waves, ST-T abnormalities, or prolonged QT interval. Findings predictive of cardiovascular disease were left ventricular hypertrophy patterns and ST-T abnormalities, or prolonged QT interval. Findings predictive of cardiovascular disease were left ventricular hypertrophy patterns and ST-T abnormalities. Increase of age from 60 to 100 years was associated with prolongation of PR and QT intervals, but shortening of the RR interval.
In the past 25 years, the mortality rate due to ischaemic heart disease in the United States of America and many other western countries has decreased significantly, whilst that in Singapore has increased steadily and unrelentlessly. Hypertension is also very common in Singapore, with a prevalence rate of 14% in those who are 20 years and above. Ischaemic heart disease and hypertension both increase dramatically with age and these 2 conditions account for a substantial proportion of the mortality and morbidity in elderly subjects, 65 years and above. Ischaemic heart disease often presents certain special problems with regard to clinical presentation, investigation and treatment in the elderly patients. For example, typical chest pain is much less frequent in elderly patients with angina pectoris or acute myocardial infarction compared to their younger counterparts. Elderly patients are also generally much more sensitive to any form of drug therapy. Therefore anti-anginal drugs such as the nitrates, beta-blockers and calcium antagonists and all types of anti-hypertensive drugs must be administered more carefully, with a smaller starting dosage and with careful monitoring of possible side-effects.
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Postectopic normalization of inverted U waves, a previously undescribed phenomenon, provides another parallel to T wave behavior.