Biomedical subjects
Publications and source records attributed to Y T Tai.
A patient with an aortic root abscess complicating Mycobacterium fortuitum prosthetic endocarditis is described. The correct diagnosis had been made preoperatively by echocardiography and was confirmed subsequently at surgery.
Electrical alternans and mechanical alternans are intriguing phenomena that have been reported to occur during tachycardias. Their precise pathophysiologic mechanism and in particular their interrelation have not been well defined. This report documents an unusual electromechanical concordance in alternans during sustained supraventricular tachycardia and ventricular tachycardia in two patients, raising interesting possibilities on the underlying mechanism of the concordant phenomena. The findings highlight the principle of excitation--contraction coupling of the heart.
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Nine patients with atrial myxoma in whom selective coronary arteriography had been performed were studied. The angiographic sign of 'tumour vascularity' was found to be present in three patients with highly vascularized atrial myxoma. The clinical significance of the angiographic sign is unknown although highly vascularized myxomata appear to have a greater propensity to bleeding into the tumour, resulting in an acute worsening of clinical symptoms. The angiographic sign of 'tumour vascularity' is not specific but useful to complement the diagnosis of an atrial myxoma. The indication for selective coronary arteriography in patients with atrial myxoma remains the detection of coronary artery disease, thus concomitant coronary artery bypass surgery could be planned preoperatively.
Recainam is a new antiarrhythmic agent with class Ic properties. To evaluate its electrophysiologic effects and antiarrhythmic efficacy in patients with recurrent supraventricular tachycardia (SVT), programmed electrical stimulation was performed in 10 patients before and after intravenous recainam (loading dose 0.8 mg/kg, infusion 1 mg/kg/h), and in four patients on oral recainam 1,200 mg/day. Five patients had atrioventricular (AV) node reentrant tachycardia; five had AV-reciprocating tachycardia. There were no significant changes in electrocardiographic and intracardiac intervals after either intravenous or oral recainam. After intravenous recainam, the ventricular effective refractory period (ERP) shortened (231 +/- 14-219 +/- 9 ms, p less than 0.05). The antegrade ERP of all three bidirectional accessory pathway markedly prolonged, but the effect on retrograde accessory pathway and AV node ERPs was unremarkable. SVT induction was prevented in three of 10 patients and SVT cycle length increased modestly in seven (357 +/- 44-374 +/- 42 ms, p = 0.07). On oral recainam, an increase in the frequency of spontaneous SVT occurred in two patients. At the doses given, recainam caused less electrophysiologic change than expected, had modest antiarrhythmic efficacy, and might have significant arrhythmogenic potential.
Cardiovascular complications are uncommon in Behçet's disease, but are frequently the cause of morbidity and mortality. Venous and peripheral arterial involvement have been well documented, but involvement of the proximal aorta has rarely been described. This report details a Chinese patient with Behçet's disease. Diffuse aortitis led to proximal aortic dilatation and severe aortic regurgitation necessitating aortic valve replacement. Histopathology of the aorta revealed features similar to those observed in other systemic diseases with aortic involvement.
Severe adverse reactions to propylthiouracil occur in 1-5% of patients. Three major side effects, namely agranulocytosis, hepatotoxicity and drug-induced hypersensitivity, have been described though these syndromes are not distinct entities and there can be overlaps in the clinical manifestations. The drug-induced hypersensitivity may be an immune-mediated reaction with multiorgan involvement in which a combination of polyarthritis, cutaneous vasculitis and fever is common. We report a patient with propylthiouracil-induced hypersensitivity with an unusual combination of high spiking fever, migratory polyarthritis, reversible sensorineural deafness, normochromic normocytic anaemia, leucocytosis and hepatotoxicity associated with polyclonal activation of multiple autoantibodies. This case illustrates the highly variable clinical manifestations of the syndrome. The prompt recovery upon withdrawal of the drug indicates the importance of early diagnosis.
To determine the incidence of venous thrombosis after long-term transvenous pacing in the Chinese, venograms were performed in 50 consecutive Chinese patients seen at the pacemaker clinic. There were 25 women and 25 men. The mean age was sixty-six years (range thirty-two to eighty-one). The indications for pacing were complete heart block in 16 patients and sick sinus syndrome in the remainder. All pacemakers were of the single-chamber ventricular pacing type and had been implanted for a mean period of four years (range two to seven). In 27 patients the route of entry for the pacing electrode was through the cephalic vein and in the other 23 patients the subclavian veins were used. Of the 50 venograms, 1 showed partial and 1 showed total obstruction at the subclavian vein. Both patients (4%) were asymptomatic. All others (96%) were normal. The incidence of venous thrombosis was not related to the routes of entry of the pacing electrodes. All patients tolerated the procedure well and had no complications. It is concluded that the incidence of venous thrombosis after long-term transvenous pacing is extremely low in the Chinese (4%), and venograms are both safe and useful for identifying venous thrombosis related to transvenous pacing.
In the absence of myocardial ischaemia, ventricular tachycardias occurring in patients with structural heart disease rarely respond to calcium antagonists like verapamil. In contrast, verapamil is markedly effective in the acute management of "supraventricular" tachycardias. Thus, intravenous verapamil has often been used for therapeutic and diagnostic purposes in patients with wide QRS complex tachycardias. This report details two unusual cases of ventricular tachycardia that are verapamil-sensitive. They highlight two major categories of "idiopathic" ventricular tachycardia, namely fascicular tachycardia and catecholamine-mediated ventricular tachycardia. The risks of verapamil administration for wide complex tachycardias are also reviewed.
In 15 patients with atrial fibrillation (AF), a single right ventricular extrastimulus (intercalated pacing) was delivered after every sensed conducted beat resulting in a reduction in rate. This method was used in 10 patients with lone AF and the average success rate of inducing coupling was 86 +/- 14% (range 64 to 100), using a mean coupling interval of 232 +/- 28 ms (range 175 to 290). During intercalated pacing, the pulse rate of AF was reduced (from 137 +/- 26 to 75 +/- 14 beats/min, p less than 0.001). Intercalated pacing resulted in enhancement of mean stroke volume (28 +/- 6 vs 44 +/- 10 ml in AF, p less than 0.0001), pulse pressure and the pulse-to-pulse regularity. Both the systolic and diastolic arterial pressures were regularized. The reduction in pulse rate during intercalated pacing was determined by the coupling interval, and the induction of concealed ventriculoatrial conduction (82 +/- 44 ms). Myocardial lactate extraction was similar during AF and short-term intercalated pacing (28 +/- 10 vs 25 +/- 9%, difference not significant). In 5 patients with severe mitral stenosis in AF, intercalated pacing resulted in an improvement in the cardiac output (3.1 +/- 0.2 vs 3.4 +/- 0.2 liters/min, p less than 0.04), a reduction in the gradient across the mitral valve (16 +/- 8 vs 10 +/- 5 mm Hg, p less than 0.02), and a reduction in pulmonary arterial and wedge pressures. This new pacing method thus achieved rapid temporary control of rate, regularity and cardiac hemodynamics during AF, which were more prominent in patients with mitral stenosis and restricted left ventricular filling.
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A 54-year-old man underwent aortic valve replacement for syphilitic aortic regurgitation. Eight years later, he was admitted with sudden precordial discomfort and symptoms of superior vena caval obstruction. Ascending aortic dissection was diagnosed by echocardiography and computed tomography of the thorax. The patient succumbed rapidly after admission. Postmortem findings and histological features were compatible with syphilitic aortitis, without significant atherosclerosis. This case report adds to the sparse literature on aortic dissection complicating syphilitic aortitis, and illustrates that, at certain stages of the disease process, syphilitic aortitis can lead to such a degree of mechanical instability of the aortic wall as to predispose to dissection.
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Subclinical myocardial involvement frequently occurs in patients with systemic lupus erythematosus (SLE). In this study, left ventricular diastolic function was assessed in 58 patients (54 female and 4 male; mean age 32 +/- 11 years) and in 40 sex-matched and age-matched healthy control subjects (37 female and 3 male; mean age 33 +/- 9 years) by means of pulsed Doppler echocardiography. All subjects had no clinical evidence of overt myocardial disease or abnormal left ventricular systolic function. Compared with the control group, patients with SLE had significantly prolonged isovolumic relaxation time (62 +/- 12 vs 80 +/- 14 msec; p less than 0.01), reduced peak early diastolic flow velocity (peak E) (82 +/- 18 vs 76 +/- 16 cm/sec; p less than 0.05), increased peak late diastolic flow velocity (peak A) (45 +/- 7 vs 53 +/- 8 cm/sec; p less than 0.01), reduced E/A ratio (1.81 +/- 0.32 vs 1.46 +/- 0.29; p less than 0.001), and lower deceleration rate of early diastolic flow velocity (EF slope) (489 +/- 151 vs 361 +/- 185 cm/sec2; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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A patient is described in whom a persistent murmur was detected after surgical ligation of an arterial duct. Subsequently, she underwent investigation and was found to have associated rare congenital anomalies of a coronary arterial fistula and a single coronary artery.
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