Comparison of immediate versus day to day variability of ventricular tachycardia induction by programmed stimulation.

The use of programmed stimulation to assess long-term oral antiarrhythmic drug efficacy for ventricular tachycardia is complicated by the fact that mode of ventricular tachycardia induction varies from day to day in the absence of drug therapy. The purpose of this prospective study was to assess whether mode of ventricular tachycardia induction is more reproducible within one study than from day to day. Thirty-nine consecutive patients with documented sustained ventricular tachyarrhythmias secondary to coronary artery disease underwent three inductions of ventricular tachycardia at 15 min intervals in the absence of drug therapy. A stimulation protocol in which the only major variable was the number of extrastimuli required for tachycardia induction was used. Subsequent day to day variability in mode of tachycardia induction was also assessed in the same patients at two further drug-free inductions at intervals of 5 +/- 2 days. The number of extrastimuli required for tachycardia induction was significantly more reproducible at the immediate repeat studies than from day to day (69% of patients versus 31%, p less than 0.01). From these data, probability tables were derived that show the likelihood that changes in inducibility at subsequent tachycardia inductions are due to chance. The QRS configuration of induced ventricular tachycardia was also more reproducible at the immediate studies (64% versus 26%, p less than 0.01). Basic electrophysiologic and stimulation variables differed over a significantly wider range from day to day than at the immediate studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Lack of effect of bretylium tosylate on electrical ventricular defibrillation in a controlled study.

The threshold stored energy and transthoracic current for electrical defibrillation were determined in dogs anaesthetised with pentobarbitone. Groups were randomly allocated to pre-treatment with either saline or bretylium. The intravenous administration of bretylium tosylate (10 to 30 mg . kg-1) did not significantly alter either measurement. The drug caused large changes in heart rate and arterial blood pressure.

Characteristics and radiofrequency ablation therapy of intermediate septal accessory pathway.

Fourteen patients (5%) with an intermediate septal accessory pathway were identified among 283 consecutive patients with the Wolff-Parkinson-White syndrome who had electrophysiologic study and radiofrequency ablation therapy. Nine were women and 5 were men (mean age 33 +/- 13 years). The resting electrocardiogram showed ventricular preexcitation in 8 patients and normal PR interval in 6. Anterograde and retrograde mapping studies revealed that the accessory pathway was para-Hisian in 11 patients and paranodal in 3. The accessory pathway was successfully ablated in 10 patients (9 para-Hisian and 1 paranodal) and damaged in 1 (para-Hisian). Treatment of 3 patients was complicated by transient atrioventricular (AV) block, of 1 by intermittent second-degree AV block, and of another by permanent complete AV block requiring implantation of a permanent pacemaker. Six patients underwent a follow-up electrophysiologic study 84 +/- 55 days after ablation; none had induction of tachycardia even after isoproterenol infusion. It is concluded that radiofrequency ablation therapy for intermediate septal accessory pathway is feasible. However, the success rate is only modest (71%), whereas complications with heart block (36%) or complete right bundle branch block (29%) are high. Thus, the procedure should be reserved for patients with life-threatening or troublesome symptomatic tachyarrhythmias.

Epidemiology of sudden unexpected death syndrome among Thai migrant workers in Singapore.

A total of 235 cases of sudden unexpected death syndrome (SUDS) among apparently healthy male Thai migrant workers in Singapore were reported between 1982 and 1990. Most of the deaths occurred during sleep and 13% were not sleep-related. The median age at the time of death was 33 years and the median interval between arrival and death was 8 months. These deaths occurred singly and sporadically throughout the year. Post-mortem examination revealed few abnormal findings except for haemorrhagic congestion or oedema of the lungs. There were moderate to severe intra-alveolar haemorrhages with some evidence of myocarditis or pneumonitis. Preliminary findings of serial sections of the hearts indicate evidence of anomalies in the cardiac conduction system. Epidemiological investigations showed that a family history of similar deaths and serological evidence of current or recent infection with Pseudomonas pseudomallei were significantly associated with SUDS. Extensive biochemical and toxicological investigations were inconclusive. There was no evidence of chronic deficiency in thiamine or potassium among the healthy Thai workers living and working in the same conditions as the cases, and no significant abnormalities were detected on electrocardiographic examination. As these migrant workers experienced various psychosocial problems which could stem from maladjustment to an urban environment, separation from the family, burden of debts and long hours of work, stress could be a precipitating factor for SUDS.

The palmaris longus tendon. Another variation in its anatomy.

The palmaris longus is one of the most variable muscles of the human body. An understanding of its variations is useful as it is often used as a tendon graft and for tendon transfer. We report another interesting variation in its anatomy.

Permanent pacemaker trends in Singapore General Hospital in the eighties.

This is a ten year survey of all the pacemakers implanted in the Department of Cardiology, Singapore General Hospital, from January 1980 to July 1989. There were 331 (164 male and 167 female) patients with pulse generators and leads implanted. The ages of the subjects ranged from 8 to 91 years (mean 63 years). Two-thirds of the patients were greater than 60 years. The indications for pacemaker implants were high grade atrioventricular block in 199 (60%) patients, sick sinus syndrome in 112 (34%) patients and in the remaining 20 (6%) of patients, no data was available, 298 (90%) patients had VVI pacing (133 were non-programmable and 165 were programmable pacemakers), 8 (2%) had AAI, 16 (5%) had DDD and the remaining 9 (3%) had VVIR mode of pacing. 282 (85%) of the patients had new pacemakers implanted while the remaining 49 (15%) patients had pacemaker replacements. At the time of replacement of pacemakers, 23 patients had upgrade of their non-programmable to programmable VVI pacemakers and 4 to DDD and VVIR pacing modes respectively. Furthermore, 293 (88%) patients had endocardial leads as compared to 38 (12%) with epicardial leads. In conclusion, most of the patients who require pacemaker implants will continue to have single chamber system. However, to improve longevity of the pacemakers, one should consider using low pacing threshold leads and programmable pacemakers.

Mortality trends in the coronary care unit.

To evaluate the clinical features, complication rates, and mortality from infarction in the coronary care unit, we analysed all cases of acute myocardial infarction admitted to the Coronary Care Unit of the Singapore General Hospital over a 4 month period in 1988. There were 184 cases of acute infarction with a male:female ratio of 3.4:1. Fifty-five percent of patients were aged 60 years or above. Complications included congestive cardiac failure in 40%, sustained ventricular tachycardia in 9%, cardiogenic shock in 18% and complete heart block in 8%. The overall in-hospital mortality was 20.6%. Multiple logistic regression analysis of clinical variables showed that of the clinical variables, age (elderly patients) and the diabetes were independently associated with a higher mortality as well as development of cardiogenic shock and sustained ventricular tachycardia. Comparing our results with previous smaller studies of CCU outcome in 1975 and 1967, there was a marked increase in the proportion of elderly patients in 1988 but despite this the overall mortality rate was not significantly different. Age is the most important clinical variable predicting outcome from infarction.

Pacing experience with the atrial screw-in leads at the Singapore General Hospital.

This is a retrospective study of atrial screw-in leads implanted at the Singapore General Hospital from January 1988 to August 1990. There were 21 (13 female and 8 male) consecutive patients, with age ranging from 17 to 79 years (mean 55 years). Thirteen patients had sick sinus syndrome and the remaining eight patients had high grade AV block. Eleven patients had AAI, six had DDD and four had DDDR pacing modes respectively. Three different models of unipolar screw-in leads were used. Eight patients had Medtronic Model 6957, seven had Medtronic Model 4057 and six had Siemens-Pacesetter Model 1007 pacing leads implanted. At the time of implant, the measured P wave amplitudes ranged from 1 to 4.8 mV (2.5 +/- 1.1 mV) and the pacing thresholds ranged from 0.5 to 2.3 volts (1.21 +/- 0.51 volts). There were no acute complications at the time of implant. On follow-up ranging from one month to two years, two patients had inadequate sensing in the atrium and one patient had high pacing threshold. There were no lead dislodgement. In conclusion, these screw-in leads can be safely used in the atrium with acceptable pacing characteristics.

Surgery for cardiac arrhythmias.

From March 1989 to March 1991, 17 patients underwent curative surgical ablation of cardiac arrhythmias at the Singapore General Hospital. In the supraventricular tachycardia group, 13 patients with the Wolff-Parkinson White syndrome (WPW) underwent surgical ablation of the accessory conduction pathway by the classical endocardial approach. Two patients who had atrioventricular nodal tachycardia (AVNRT) underwent surgical dissection around the atrioventricular node to divide one of the dual conduction pathway responsible for the tachycardia. In the ventricular tachycardia group, two patients underwent surgical ablation of the arrhythmic focus. There was no operative mortality in the supraventricular tachycardia group and there were no late deaths to date. All these patients underwent electrophysiological study just before discharge and most of them had a repeat test six months later. In the Wolff-Parkinson White group, surgical ablation was completely successful in 12 patients (92%), preexcitation recurred in one patient (8%) but non had recurrence of supraventricular tachycardia. The two patients who had atrioventricular nodal tachycardia were completely cured of recurrent supraventricular tachycardia and had normal atrioventricular conduction. In the ventricular tachycardia group, one was cured with no recurrence of tachycardia, is not on medication and is in New York Heart Association Class I status. The other died postoperatively of recurrent ventricular tachycardia and low cardiac output syndrome.

Cardiac life support training: the Ministry of Health's experience.

This study reviews the records of all cardiac life support training courses conducted at the Ministry of Health's Life Support Training Centre situated in Singapore General Hospital over a six period from 1985 to 1990. A total of 1,789 persons were trained in Basic Life Support (BCLS), 65 as BCLS Instructors, 267 in Advanced Cardiac Life Support (ACLS), 276 in Emergency Cardiac Care (ECC) and 24 in Emergency Cardiac Defibrillation (ECD). These courses have involved a total of 1111 doctors, 1248 nurses and 62 ancillary staff. At the end of the course, 90.7% of those learning BCLS agreed that they would use their CPR skills, if required. Only 60% felt they would use mouth-to-mouth ventilation. Of 415 who expressed an interest in becoming instructors, 15.7% have, to-date, been trained. While more than 80% of persons learning, ACLS were doctors, only 25% of these were willing to instruct. There are currently 14 ACLS instructors. The ECC courses were modified from the ACLS course and taught to Emergency Room doctors only. It was found to be immensely popular with 98% expressing benefit. The ECD programme trained emergency ambulance nurses in the use of semi-automatic electrical defibrillators. The marked increased in yearning for cardiac life support skills amongst medical and nursing staff has been a major factor in the proliferation of life support training programmes at the Centre. Nurturing this enthusiasm is the key to ensuring that the programmes continue to expand for the benefit of both inpatients and the out-of-hospital lay public.

Anti-arrhythmic surgery for atrioventricular junctional and atrioventricular re-entrant tachycardia--a report of six cases.

Since 15th March 1989, six patients with recurrent supraventricular tachycardia (SVT) had antiarrhythmic surgery performed. There were 4 males and 2 females, ages ranged from 23 to 62 years (mean 41 years). Two of these patients with the Wolff Parkinson White (WPW) syndrome also had syncope. Five of these patients had atrioventricular re-entrant tachycardia (AVRT) involving the bypass tracts. Two patients with the WPW syndrome had persistent antegrade conduction, two had intermittent conduction and the last patient had no antegrade conduction via the bypass tract. The bypass tracts were localised at the left free wall in all the five patients. Only one patient had atrioventricular junctional re-entrant tachycardia (AVJRT) of the slow-fast type. The indications for surgery for these patients include failed medical therapy, "dangerous" arrhythmias and patient's preference. All the patients had surgery performed using the endocardial dissection technique on the cardioplegic heart. There were no perioperative mortality and morbidity. All the patients were discharged within 2 weeks. To date, none of the patients had clinical recurrence of SVT and only one patient remained in atrial fibrillation and is on digoxin. In conclusion, antiarrhythmic surgery should be considered for patients with "symptomatic" palpitations as it is curative with a resumption to normal life.

Elderly patients with perforated peptic ulcers: factors affecting morbidity and mortality.

Morbidity and mortality of perforated peptic ulcers (PPUs) have been higher when they occur in elderly patients. Seventy-three PPUs were reviewed to determine the factors accounting for the poor outcome in patients at or above 65 years old (elderly PPU). The presentation of 44 young PPUs was compared to 29 elderly PPUs. Delay in diagnosis, associated comorbid factors and shock on admission were found to be the primary factors. There was a significant difference between the two groups in terms of duration of pain before the diagnosis was made (8.2 h vs 16.4 h) (P < 0.05). The delay in diagnosis was partly due to the vague presentation, as 41.4% (11 patients) of the elderly presented with abdominal pain not localized in the epigastrium. In addition, 55.2% (16) of elderly patients did not have a history of prior ulcer disease and one-third (nine) did not have air under the diaphragm on chest X-ray. Significant comorbid factors were present in 65.5% compared to 15.9% in the younger group (P < 0.001). Shock on admission was present in six (20.7%) elderly patients, but only in one (2.3%) young patient (P < 0.05). As a result, morbidity was 89.6% in the elderly group compared to 27.2% in the younger patients (P < 0.001). Wound complications accounted for a significant proportion of the morbidity. Mortality was 17.2% and 2.3% respectively (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Early ambulation following diagnostic 7-French cardiac catheterization: a prospective randomized trial.

There is a paucity of randomized studies concerning transfemoral cardiac catheterization and its complications, in particular that of 7F catheterization. Accordingly, we conducted a prospective, randomized trial comparing early ambulation (group A) 6 hr after diagnostic 7F cardiac catheterization versus late ambulation (group B) the following morning. A total of 273 patients were randomized in the study; 142 in group A and 131 in group B (NS). Except for a difference in the indications for catheterization, the baseline and procedure-related parameters were similar between the 2 groups. Early hematoma (formed within 6 hr) developed in 6 (4%) and 7 (5%) patients in groups A and B, respectively (NS). Similarly, there was no difference in the incidence of late hematoma formation (2% in each group). All hematomas detected were small and required no surgical intervention or extension of hospital stay. Our data showed that early ambulation following 7F left heart catheterization is feasible and safe. The access site complication rate is acceptably low and minor in nature.

Proarrhythmic effects of antiarrhythmic drugs.

Drugs that are described as antiarrhythmic drugs may actually aggravate arrhythmia in several ways and these are termed proarrhythmic effects. The most common type of proarrhythmia is a paradoxical increase in the frequency of episodes of the target arrhythmia. This type of effect had not been suspected until recently and has not been widely publicized. It is a phenomenon common to all antiarrhythmic drugs when they are used to treat arrhythmias based on a re-entrant mechanism (the most common mechanism of clinical arrhythmias). Different drugs vary in their tendency to produce this type of proarrhythmic response. These differences are explicable in terms of the relative effects of the drugs on refractoriness and conduction times in the re-entrant circuit. Proarrhythmic effects are most important in the treatment of ventricular tachycardias because recurrences are often fatal. Proarrhythmic effects on ventricular tachycardia can now be predicted at electrophysiological study before commencement of long-term therapy, and potentially dangerous treatment can be avoided. The key to proper treatment to proarrhythmia is to recognize that it is a drug-induced problem and to withdraw the offending drug.