Stenting of partial and total coronary occlusions in Trinidad and Tobago

In order to evaluate the efficacy and safety of coronary stenting, we reviewed the first 32 consecutive patients (34 vessels) who underwent elective coronary stenting during the period August 1999 to August 2000 inclusive at the Digital Lab installed at the Eric Williams Medical Sciences Complex, Trinidad and Tobago. Aspirin, heparin and ticlopidine were used routinely. Abciximab was used in selected cases (38). The mean age of patients was 55 +/- 10 years. Eighty-one per cent were male, 52 were hypertensive and 21 were diabetic. Sixty-five per cent had severe angina. Prior Coronary Artery Bypass Grafting (CABG) was performed in 3 and previous Percutaneous Transluminal Coronary Angioplasty (PTCA) in 3. Multivessel disease was present in 43. The mean left ventricular ejection fraction was 53 +/- 12. The culprit lesion was located in either the native left anterior descending (LAD) coronary artery (53), right coronary artery (RCA) (31), circumflex artery 13 and saphenous vein graft (3). The mean baseline diameter stenosis was 91 +/- 9 and this was reduced to 13 +/- 33 after stenting. Procedural success was 100 for 26 partially occluded vs 50 for 8 totally occluded vessels. For the total occlusions, procedural success was inversely related to the duration of the occlusion. There were no cases of death, acute vessel closure, Q-wave myocardial infarction, repeat PTCA or emergent Coronary Artery Bypass Graft (CABG) during and following the procedure. Distal embolization occurred in one patient. The mean duration of hospital stay was one day (for 30 outpatient cases). One patient had recurrence of symptoms with a negative stress test. No patient underwent repeat angiography during the first year of follow-up. Coronary stents were successfully implanted at a tertiary care facility in the Caribbean with low in-hospital morbidity and mortality. Stents markedly reduced the diameter stenosis of the coronary lesion during PTCA. The incidence of clinical restenosis was low. Coronary revascularisation can be successfully achieved by coronary stenting in the Caribbean.

Evaluation of inhibitory effect of diphenhydramine on benzodiazepine dependence in rats.

Effect of diphenhydramine was investigated on withdrawal signs in lorazepam dependent rats. Physical dependence was produced by giving lorazepam admixed with the food in the following dose schedule: 10 x 4, 20 x 4, 40 x 4, 80 x 4 and 120 x 7 (mg/kg, daily x days). The parameters observed during the periods of administration of lorazepam and after its withdrawal were spontaneous locomotor activity (SLA), body temperature, reaction time to pain, foot shock aggression (FSA) and audiogenic seizures. Diphenhydramine was administered orally in the dose schedules of once daily (10, 20 and 40 mg/kg) and twice daily (5, 10 and 20 mg/kg) in separate groups during the withdrawal period. The withdrawal signs observed in control group (without diphenhydramine) were hyperkinesia, hyperthermia, hyperaggression and audiogenic seizures. Hyperkinesia and hyperthermia were blocked in all the groups of diphenhydramine-treated rats. FSA was inhibited only by diphenhydramine (10 and 20 mg/kg) given twice daily. Audiogenic seizures were completely blocked by once daily (20 and 40 mg/kg) as well as twice daily (20 mg/kg) doses of diphenhydramine. It may be concluded that diphenhydramine exerts a protective effects on benzodiazepine withdrawal syndrome.

Effect of calcium channel blockers on withdrawal syndrome of lorazepam in rats.

Effects of calcium channel blockers were investigated on withdrawal signs in lorazepam dependent rats. Physical dependence was produced by giving lorazepam admixed with the food in the following dose schedule: 10 x 4, 20 x 4, 40 x 4, 80 x 4 and 120 x 7 (mg/kg daily x days). Parameters such as body weight, food intake, spontaneous locomotor activity (SLA), body temperature, reaction time to pain, foot shock-aggression (FSA) and audiogenic seizures were observed during the period of administration of lorazepam and after its withdrawal. Calcium channel blockers viz. verapamil, nifedipine and nimodipine in different doses were administered orally twice daily in separate groups during the withdrawal period. The withdrawal signs observed in control group (without calcium channel blockers) were hyperkinesia, hyperthermia, hyper-aggression and audiogenic seizures. The administration of verapamil (5-20 mg/kg), nifedipine (1.75-7 mg/kg) and nimodipine (5-20 mg/kg) during the withdrawal period of lorazepam showed dose dependent significant blockade of all the withdrawal signs. Audiogenic seizures were completely blocked by 20 mg/kg dose of verapamil and nimodipine while nifedipine was partially effective. It may be concluded that calcium channel blockers exert protective effects on benzodiazepine withdrawal syndrome.

Complications in 1000 consecutive treadmill tests.

Complication in 1000 consecutive Tread Mill Tests (TMT) done at the Cardiology Centre of Command Hospital (SC) Pune are reported. The tests were done following Bruce Protocol and analysed based on Selzer's criteria. Complications were noted in 18 cases (1.8%) which included ventricular fibrillation, ventricular tachycardia, atrial fibrillation, malignant VPBs, conduction disturbances, asystole following hyperventilation (HV), complete SA block following HV, atrial flutter following HV, hypotension and severe angina requiring ICCU care. No acute myocardial infarctions or deaths were noted. Coronary arteriography (CART) was done in 50 (5.0%) selected cases including 10 with complications. It is concluded that TMT is a safe procedure if carried out after proper patient selection and under supervision of an experienced and efficient team.

Dopaminergic involvement in the effects of piracetam on foot shock induced aggression in mice.

The effects of piracetam-a nootropic drug, were studied on foot shock induced aggressive behaviour in mice. Intraperitoneal injection of piracetam resulted in a biphasic response i.e.; initial excitation followed by inhibition of the aggressive behaviour. The initial excitation was observed with only 100 and 50 mg/kg doses of piracetam and not with the lower doses (25 and 12.5 mg/kg). Dopaminergic receptor blocker haloperidol (0.5; 0.25 and 0.12 mg/kg, ip) and pimozide (1.0 mg/kg, ip) produced inhibition of the aggressive behaviour. Lowering of the dose of haloperidol to 0.06 mg/kg resulted in an excitation of the aggressive behaviour. No motor deficit or catalepsy was observed with either haloperidol or pimozide injected in the doses indicated above. Pretreatment of the mice with haloperidol (0.12; 0.25 and 0.5 mg/kg) led to a dose-dependent blockade of the piracetam (100 mg) induced excitation of the aggressive behaviour, but the inhibition of the aggressive behaviour was not blocked by pretreatment with the excitatory dose of haloperidol. Similarly, pimozide (1.0 mg/kg) pretreatment also effectively blocked the excitatory effect of piracetam on aggressive behaviour. The results suggest the involvement of dopaminergic system in the excitatory effects of piracetam on aggressive behaviour. The inhibitory effect of piracetam appears to be independent of this mechanism.

Excessive polycythaemia of high altitude. Pulmonary function studies including carbon monoxide diffusion capacity.

Pulmonary function studies were done in 21 soldiers (low landers) posted at high altitude (average height 4773 metres) for prolonged periods (average 77.09 months), who had developed excessive polycythaemia, mean haemoglobin concentration being 23.06 g/dl. Studies revealed significant reduction in diffusion capacity of lungs which gradually returned to normal on sojourn at low altitudes for 70 days. Both the degree of polycythaemia and reduction in lung diffusion capacity were much more pronounced in smokers than in non-smokers. Vital capacity did not show any difference in these subjects while forced expiratory volume in 1 sec and ratio of forced expiratory volume to vital capacity (FEV1/VC) revealed only obstructive features in smokers.