[Show abstract][Hide abstract] ABSTRACT: Electrophysiologic effects and the efficacy of single-dose intravenous (i.v.) amiodarone were compared with those of long-term oral therapy in 9 patients of AV nodal reentrant tachycardia (AVNRT) utilising slow pathway (SP) for anterograde and fast pathway (FP) for retrograde conduction. Electrophysiologic data were obtained by programmed electrical stimulation (PES) before, 15 to 30 minutes after i.v. amiodarone (5 mg/kg body-weight over 10 minutes) and a mean of 64.6 +/- 23.7 days after oral therapy, on a maintenance dose of 200 to 400 mg daily. There was no significant influence on the sinus cycle length and infranodal conduction (HV) by i.v. or oral amiodarone as compared to pre-drug values. AV nodal conduction, evaluated by AH interval, increased significantly and comparably with both (8% after i.v., 10% after oral; p = NS). Anterograde conduction through SP, as evidenced by pacing cycle length producing AH block, was prolonged by both (31% after i.v., 52% after oral; p = NS). Oral amiodarone, however, was more effective than i.v. in lengthening the effective refractory period (ERP) of anterograde FP (45% vs 17%, p < 0.05). Although both depressed retrograde conduction significantly, long-term oral amiodarone was more effective in prolonging the paced cycle length (PCL) producing ventriculoatrial (VA) block (79% vs 50%; p < 0.05) and ERP of VA conduction system (72% vs 42%; p < 0.01). AVNRT was successfully terminated in 7 patients after i.v. amiodarone. However, tachycardia was reinducible in 3 patients after i.v. and in none after long-term oral therapy. None had clinical recurrence of tachycardia on maintenance oral therapy. The mean concentration of the drug was 3.1 +/- 1.81 micrograms/ml after i.v. and 1.3 +/- 0.47 micrograms/ml after oral therapy (p < 0.05). These results. suggest that i.v. amiodarone terminated AVNRT by depressing both anterograde and retrograde limbs of the reentrant circuit and eventually blocking one of these. Oral therapy prevented recurrence and reinducibility by its predominant effect in prolonging refractoriness of the atrium and ventricle, and depressing conduction through the retrograde FP. It is concluded that i.v. amiodarone is an effective drug in acute termination of tachycardia mediated by AV nodal reentry and that long-term oral therapy is excellent in preventing recurrence and reinducibility of tachycardia. There are significant differences in the electrophysiologic properties and mechanism of action between the two forms, not influenced by the blood levels of amiodarone.
No preview · Article · Mar 1996 · Indian Heart Journal
[Show abstract][Hide abstract] ABSTRACT: Echocardiographically determined ventricular load and performance were compared in 40 consecutive patients with severe mitral stenosis before and 24 h after successful and uncomplicated balloon mitral valvuloplasty in order to clarify the role of loading conditions in causation of reduced left ventricular ejection fraction. After valvuloplasty, mitral valve area increased 2-fold. A modest increase in ejection fraction (53 +/- 11% to 57 +/- 8%, P = 0.021) occurred with an insignificant increase in end-diastolic volume (44 +/- 10 to 48 +/- 16 ml/m2, P = 0.063) and no change in wall stress (61 +/- 19 to 59 +/- 19 kdynes/cm3, P = 0.85) (10(5) dynes = 1 N). There was no correlation between changes in fractional shortening and wall stress (r = 0.07) and between changes in end-diastolic volume and fractional shortening (r = 0.12). Contractile performance estimated by a performance-afterload relation was unchanged after the valvuloplasty. Factors other than a change in loading conditions might be responsible for a modest improvement in ejection performance following mitral valvuloplasty.
No preview · Article · Apr 1995 · International Journal of Cardiology
[Show abstract][Hide abstract] ABSTRACT: Although bifurcation lesions in the coronary arteries can be dilated with balloon angioplasty, directional atherectomy is emerging as the treatment of choice in patients with large arteries. In this study, we report the immediate results and acute complications of treating bifurcation lesions in the coronary arteries with directional atherectomy in 9 patients, ranging in age from 33 to 60 (mean 56.7 +/- 10.8) years. All patients had true bifurcation stenoses with luminal diameter narrowing of more than 70 percent in both the primary vessel and the side branch. The lesions involved the left anterior descending (LAD)-diagonal system in 5, left circumflex (LCx)-obtuse marginal (OM) in 2, distal right coronary artery (RCA) in 1 and bifurcation of a large first diagonal branch in one patient. Double-wire atherectomy technique was used in 4 patients, although 7 had an additional wire in the side branch during post-atherectomy balloon angioplasty. The procedure was successful in all patients (100%), with luminal diameter stenosis decreasing from 93 +/- 7.5 percent to 6 +/- 8.6 percent in the primary vessel and from 83 +/- 9.2 percent to 13 +/- 9 percent in the side branch. There were no major complications. Minor complications included non-flow limiting dissection in 4 patients, distal migration of thrombus in one, occlusion of 2 small distal branches of the diagonal in one and entwinement of the guidewires in one. In conclusion, directional atherectomy can be performed safely and successfully for dilatation of complex bifurcation lesions in the coronary arteries without any major complications using the double-wire or sequential atherectomy technique.
No preview · Article · Mar 1995 · Indian Heart Journal
[Show abstract][Hide abstract] ABSTRACT: Flecainide is a class IC antiarrhythmic agent with a controversial role in the treatment of ventricular arrhythmias following myocardial infarction after the publication of the Cardiac Arrhythmia Suppression Trial (CAST). To assess its utility in paroxysmal supraventricular tachycardia (PSVT), we evaluated the electrophysiologic effects and therapeutic efficacy of intravenous flecainide, administered in a dose of 2 mg per kg body weight in 26 patients of PSVT, studied by programmed electrical stimulation. The patients' age ranged from 18-49 years (mean: 27 +/- 8) and none had organic heart disease. The mechanism of PSVT was atrioventricular nodal reentry (AVNRT) with anterograde conduction through slow pathway and retrograde through fast pathway in 14, and atrioventricular reentry (AVRT) utilizing an accessory pathway in 12 patients. Flecainide was successful in terminating the tachycardia in all (100%) patients of AVNRT and 11 (92%) patients with AVRT. In both the types, the tachycardia was terminated by selective block in conduction through the retrograde limb of the reentry circuit. The drug also produced a complete anterograde block with abolition of preexcitation in 6 out of 8 patients with WPW syndrome. After the drug, the tachycardia was reinducible in one patient of AVNRT and 4 with AVRT. The cycle length of inducible tachycardia increased from 295 +/- 25 ms to 389 +/- 24.5 ms after flecainide (p < 0.001). There were no adverse haemodynamic effects of the drug. Our results, thus, showed that intravenous flecainide is a highly effective and safe antiarrhythmic drug for termination of PSVT mediated by atrioventricular nodal and atrioventricular reentry mechanisms without producing any adverse effects.(ABSTRACT TRUNCATED AT 250 WORDS)
No preview · Article · Jan 1995 · Indian Heart Journal
[Show abstract][Hide abstract] ABSTRACT: Clinical and electrophysiological features of 20 patients presenting with ventricular tachycardia (VT) of left bundle branch block (LBBB) morphology without evidence of coronary artery disease were studied. The mean age of the patients was 35.2 +/- 12 (range 15-57 years). The rate of VT varied between 140-240/min (182 +/- 80). Six (30%) patients experienced giddiness or syncope during palpitations. Structural heart disease was found in 10 (50%) of these patients, which included arrhythmogenic right ventricular dysplasia in five, submitral left ventricular (LV) aneurysm in one, anterolateral LV dyskinesis in one, dilated cardiomyopathy in one, endomyocardial fibrosis in one and nonobstructive hypertrophic cardiomyopathy in one case. Ten patients were free of structural heart disease. Electrophysiological study was done in all patients. VT with same morphology as spontaneous VT was inducible in only 14 patients. Seventeen patients were treated medically with total or partial amelioration of symptoms. In three patients, two with arrhythmogenic right ventricular dysplasia and one with structurally normal heart, who were unresponsive to drug therapy, the VT focus could be mapped in right ventricular outflow tract and successful electrical ablation was done. Thus in patients who present with VT with LBBB morphology, the heart is often structurally normal but organic disease is not uncommon, and should be carefully searched.
No preview · Article · Nov 1994 · Indian Heart Journal
[Show abstract][Hide abstract] ABSTRACT: Long term performance of 163 atrial leads implanted in 158 patients between July 1981 and June 1993 was evaluated. There were 122 DDD and 36 AAI units, with 125 (77%) polyurethane and 38 (23%) silicone leads. One hundred and nine (67%) unipolar and 54 (33%) bipolar leads were used. Patients were followed in the Pacemaker Clinic for 6 to 124 months (mean 50 +/- 39 months). Five patients were lost to follow up. Transient malfunction was observed in 18 cases (sensing 13, pacing 5) within the first 2 weeks. In 13 cases failure to sense subsided spontaneously and in 4 pacing malfunction could be corrected by reprogramming. Lead dislodgement occurred in 4 patients (2.5%), all within the first week. After the 1st month malfunction was uncommon. Between 1 and 12 months undersensing occurred in 4 (2.5%). In 3 cases it could be corrected by reprogramming. In the first year, reoperation was performed in 5 cases for lead related problems (3 dislodgements, 2 insulation failures). Beyond 12 months complications were as follows: failure to sense-8 (5%), failure to pace-3 (2%), insulation break -1 (0.6%). Majority of these problems could be managed by reprogramming. Reoperation was performed in 1 case with insulation break. The pacing mode had to be changed in 5 (3%) patients with dual chamber units who had loss of P wave sensing. During follow-up 98%, 98%, 96%, 95% and 83% of the leads were working satisfactorily at 1,2,3,4 and 9 years respectively. Thus atrial leads have excellent long term performance and an acceptable rate of late malfunction.
No preview · Article · Jan 1994 · Indian Heart Journal
[Show abstract][Hide abstract] ABSTRACT: Percutaneous balloon pulmonary valvuloplasty for congenital pulmonary valve stenosis was performed in 40 adult patients (aged 18 to 56 years). The duration of follow-up was 24.5 +/- 11.5 months. The peak systolic pressure gradient from the right ventricle to the pulmonary artery decreased from 107 +/- 29 mm Hg to 37 +/- 25 mm Hg immediately after the procedure. On follow-up, gradient obtained either by cardiac catheterization or Doppler echocardiography was 31 +/- 13 mm Hg. In eight patients with residual gradient after valvuloplasty of > 50 mm, the mean peak systolic gradient decreased from 74.5 +/- 18.3 to 33.5 +/- 13.9 mm Hg on follow-up. Thus balloon pulmonary valvuloplasty is a safe and effective procedure for the treatment of adult patients with pulmonic stenosis; there is a tendency for high residual gradients to regress on follow-up.
No preview · Article · Dec 1993 · American Heart Journal
[Show abstract][Hide abstract] ABSTRACT: The long term performance of various pacing leads in use for at least one year is reported from one centre. Between January 1975 and December 1990, 1056 cardiac pacing leads were implanted in 881 patients (mean age 57 +/- 13 years). Eight hundred and three leads were silicone insulated (SI) and 253 leads were polyurethane insulated (PUI). Leads from different manufacturers were used (Medtronic, CPI, Telectronics). The average duration of follow up was 56.6 +/- 77 months (range 12-221 months) for SI and 47.1 +/- 24 months (range 12-99 months) for PUI leads. Overall lead failure occurred more often in the PUI group (n = 46, 18.2%) compared to SI group (n = 93, 11.3%, p < 0.025). Majority of lead failures occurred in the first 36 months after implantation. In particular, Medtronic models 6971, 6972 (urethane) and 6901 (silicone) showed higher rate of complications (25.5%, 26.3% and 44.5% respectively).
No preview · Article · May 1992 · Indian Heart Journal
[Show abstract][Hide abstract] ABSTRACT: Conflicting data have been reported regarding adjustment of atrioventricular (AV) interval to maximise hemodynamic performance of dual chamber pacemakers. Eleven consecutive patients with complete heart block and dual chamber pacemakers were paced at three AV intervals (150, 200, 250 msec) and free running rates (60-93 bpm, mean 73 +/- 12 bpm) with simultaneous measurements of cardiac output, atrial contribution to left ventricular filling, left ventricular ejection fraction, and peak aortic velocity and acceleration by echo-Doppler techniques to define the optimum AV delay. At all the three AV intervals tested there was no difference in cardiac output (4.7 +/- 0.96, 4.83 +/- 1.12, 4.77 +/- 1.19 litres/min respectively, p = NS), left ventricular ejection fraction (60.2 +/- 10.6%, 61.2 +/- 9.9% and 64 +/- 8.3%, p = NS), atrial contribution to left ventricular filling (0.37 +/- 0.10, 0.38 +/- 0.09, 0.36 +/- 0.16, n = 8, p = NS), peak aortic velocity (104 +/- 8, 105 +/- 12, 104 +/- 13 cm/sec, p = NS) and aortic acceleration (19.68 +/- 4.26, 20.4 +/- 5.58 and 19.0 +/- 4.54 m/sec2, p = NS). Compared to AV delay of 150 msec an increase in cardiac output of 0.5 L/minute was observed in three patients at an AV delay of 200 msec and in one patient at the AV delay of 250 msec. These data suggest that it is difficult to generalize an optimum AV delay in patients with dual chamber pacemakers. With the AV interval in the range of 150-250 msec, only a minority of patients could improve their haemodynamics at rest by adjusting this interval if the baseline cardiac function was normal.
No preview · Article · Mar 1992 · Indian Heart Journal
[Show abstract][Hide abstract] ABSTRACT: Twelve years experience with pacemaker re-use is reported. Between November 1979 and December 1991, forty two pacemakers were re-used in 42 patients after in-hospital reconditioning. There were 31 males and 11 females in the age range of 29 to 84 years (mean 59 +/- 13 years). In 29 patients, the pulse generator was explanted because of pocket infection and/or impending extrusion, and it was re-implanted at a new site after sterilization. In the remaining 13 patients pacemakers explanted from other patients were implanted because of economic reasons. All patients were regularly followed up in the pacemaker clinic for a mean duration of 34 +/- 35 months (range 6-126 months). There was one infection and one erosion after 12 and 27 months respectively. One of these units was resterilized and implanted without any recurrence of infection or erosion over a follow up of 12 months. There was no adverse reaction or pulse generator failure. Our experience suggests that the use of refurbished pacemakers is a safe and economically viable option.
No preview · Article · Jan 1992 · Indian Heart Journal
[Show abstract][Hide abstract] ABSTRACT: Coronary cine-angiograms of 1,042 patients were reviewed for the presence of ectasia of major coronary arteries. Ectasia or irregular dilatation of the coronary artery was defined as 1.5 times diffuse or segmental dilatation as compared to segment of normal caliber coronary artery. Forty-one (3.9%) patients were found to have diffuse or localised coronary artery dilatations with segments of normal caliber throughout the length of major vessels. Mean age of the patients was 52 years, and majority were males (39, 95%). Right coronary artery (RCA) and left circumflex (Cx) were involved in 23 (56%) each, left anterior descending (LAD) in 15 (37%), obtuse marginal in 4 (10%) and left main in 2 (5%). Multiple vessel involvement was present in 21 (51%). Evidence of myocardial infarction was present in 21 (51%). Major risk factors were not different from the patients with coronary artery disease without ectasia.
No preview · Article · Sep 1989 · Indian Heart Journal
[Show abstract][Hide abstract] ABSTRACT: Frequency and duration of silent myocardial ischemia (SMI) on Holter recording were determined in 20 patients with unstable angina before and after 4 weeks of intensive triple drug therapy with oral nitrates (20-80 mg daily), betablocker (metoprolol 100-200 mg/day) and calcium channel blocker (nifedipine 40-80 mg/day). The number of ischemic episodes decreased from 445 (409 silent) to 149 (140 silent) (p less than 0.001), and mean duration of silent and symptomatic ischemia per patient decreased from 5.9 +/- 3.3 minutes to 2.4 +/- 2.6 minutes (p less than 0.001) and 4.1 +/- 5.5 minutes to 1.4 +/- 2.8 minutes (p less than 0.001) respectively. Intensive medical therapy is effective in ameliorating SMI in patients with unstable angina.
[Show abstract][Hide abstract] ABSTRACT: The effect of propranolol and acebutolol therapy on serum lipoproteins was studied in thirty patients (mean age 43.9 +/- 8.7 years) with essential hypertension and/or stable myocardial ischaemia. Patients received six weeks therapy with propranolol (80-160 mg per day) and acebutolol (400-800 mg per day) each in random order and were changed over from one to the other beta-blocker after 6 weeks therapy. On propranolol treatment there was no significant effect on total cholesterol and LDL-cholesterol but the concentration of serum triglycerides (94.2 +/- 37.7 to 129.1 +/- 41.2 mg/dl) and VLDL cholesterol (18.9 +/- 7.8 to 26.1 +/- 8.1 mg/dl) significantly increased, concentration of HDL cholesterol (49.5 +/- 9.4 to 42.4 +/- 8.7 mg/dl) significantly decreased (p less than 0.01). Atherogenic index also worsened from 4.17 +/- 0.48 to 5.15 +/- 0.54 (p less than 0.05) on propranolol therapy. Acebutolol therapy, on the other hand, produced no significant change in the concentration of total cholesterol, triglycerides, HDL cholesterol, LDL cholesterol and VLDL cholesterol.
[Show abstract][Hide abstract] ABSTRACT: Records of 98 patients who had dual chamber pacemakers implanted at our institution and had a follow up for at least 6 months (range 6-90 months, mean 47.8 months) were analysed for long term performance of the pacemakers. There were 78 males and 20 females in the age range of 14 to 81 (mean 51.1 +/- 13.6) years. The mode of pacing was VDD in 12, DVI in 9 and DDD in 77 patients. Atrial malsensing was seen in 15 (16.7%) cases and generally occurred within the first week of implantation. Atrial lead dislodgement occurred in 4 cases (4.1%). Most of the problems related to atrial lead could be managed conservatively and re-operation was performed in only 4 cases. Other problems encountered on follow up included cross talk in one, endless loop tachycardia in 4, and pulse generator pocket erosion or infection in 4 (4.1%) patients. There were two instances of ventricular undersensing and one instance of insulation failure in the ventricular lead. A total of 16 patients underwent elective replacement of pulse generator 53-84 months (mean 66.3) following the initial implants. It is concluded that the incidence of pacemaker malfunction and other problems with dual chamber pacemaker implantation are not high; and most cases can be managed by conservative measures such as reprogramming.
[Show abstract][Hide abstract] ABSTRACT: Forty-two patients (mean age 50 years) with chronic stable angina pectoris were subjected to exercise treadmill testing, coronary arteriography and left ventricular cineangiography. Twenty-one of these patients also underwent Holter monitoring for 24 hours. On exercise treadmill testing, angina was the endpoint in 24 (57%), while 18 (43%) developed significant ST segment depression without symptoms. Holter monitoring in 27 patients revealed a total of 248 episodes of myocardial ischaemia of which 210 (84%) were asymptomatic. ST segment depression at 80 mS from J point varied from 1 to 4 mm, and the average duration of ischaemic episodes during Holter monitoring was 9 minutes (range 30 seconds to 1 hour). Heart rate during the ischaemic episodes varied between 65-85 beats/minute. Coronary angiography revealed triple vessel disease in 22 (52%) and double vessel and single vessel involvement in 10 (24%) each. Left ventricular ejection fraction was less than 50% in only 3 (7%) patients. Thus silent myocardial ischaemia is detected frequently in patients with angina pectoris. It occurs during routine daily activity, and on exercise. Heart rate at which silent myocardial ischaemia occurs is much less during daily activity as compared to exercise induced ischaemia. All patients who were detected to have silent myocardial ischaemia had significant coronary artery disease. These findings are of prognostic and therapeutic value.