Comparison of electrophysiologic effects and efficacy of single-dose intravenous and long-term oral amiodarone therapy in patients with AV nodal reentrant tachycardia.

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.

Transcatheter closure of atrial septal defect using buttoned device--Indian experience.

Transcatheter closure of secundum atrial septal defect (ASD) < 21 mm in diameter with adequate septal margins, assessed by transthoracic echocardiography (TTE) was attempted using Sideris buttoned device under fluoroscopic and TTE guidance in 27 patients (age range 5-35 years). The stretched diameter of ASD estimated by balloon sizing at cardiac catheterization was, on an average, 3 mm larger than assessed on TTE. A 25 to 50 mm second-generation Sideris device could be successfully implanted in 24 patients, with disappearance of left-to-right shunt, assessed by colour flow mapping on TTE in 17 patients. Residual shunt of 0.12-0.54 L/min/m2 was seen on day one in 7 patients which increased on follow-up in 3 patients over a period of 12 months. The maximum shunt in one patient was 1.1 L/min/m2. On follow-up (14.5 +/- 3.8 months), the device was in a stable position in all patients evaluated by fluoroscopy and TTE, and intracardiac ultrasound study in two patients. The procedure was unsuccessful in 3 patients, due to unbuttoning of the device in one and recurrent slippage of the device through the ASD in two patients. Mitral regurgitation was detected in 5 patients on follow-up (mild in 4 and moderate in 1). There was no mortality and none of the patients required any surgical intervention. It is concluded that transcatheter closure of some selected cases of secundum ASD can be safely and effectively done using Sideris buttoned device through a small sheath; however, a centering device is likely to close larger defects with less interference with mitral valve function.

Electrophysiologic effects and therapeutic efficacy of intravenous flecainide for termination of paroxysmal supraventricular tachycardia.

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)

Clinical, angiographic and histopathological predictors of restenosis after directional coronary atherectomy.

Out of 127 directional coronary atherectomy (DCA) procedures done in our laboratory, there were 81 patients who had completed a minimum of six months of follow-up. To study the factors predisposing restenosis after successful DCA, we analysed the clinical and angiographic profile of the patients and the histopathological findings of the excised tissue in 44 patients whose complete follow-up data was available with us. The indication of DCA was an extremely eccentric significant stenosis located in the proximal or midsegment of a large vessel (> or = 3 mm size) in 97 percent of the cases. Angiographic restenosis, defined as more than 50 percent luminal diameter stenosis was absent in 24 (54.5%, Group A) and present in 20 (45.5%, Group B) patients. On univariate analysis, the factors which predisposed to restenosis were: (i) left anterior descending location, (ii) longer lesion length (9.6 +/- 3.1 mm vs 5.2 +/- 1.6, p < 0.01) and (iii) greater post-procedure residual luminal diameter stenosis (13.1 +/- 10.8% vs 4.3 +/- 6%, p < 0.01). No significant difference was found between the two groups for other variables like unstable angina, the location and the morphological characteristics of the lesion and the ratio of the vessel diameter to the size of the Atherocath. Histopathological examination of the retrieved tissue revealed the presence of media with or without external elastic lamina in 8 (33%) patients in Group A--without restenosis compared to only 1 (5%) patients in Group B--with restenosis (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Directional atherectomy for the dilatation of bifurcation stenoses in the coronary arteries.

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.

Comparative evaluation of left ventricular function in sick sinus syndrome on different long-term pacing modes.

Single-chamber ventricular pacing has been implicated in the development or progression of congestive heart failure in patients with sick sinus syndrome (SSS). To define the exact role of pacing modality in causation of congestive heart failure, quantitative two-dimensional echocardiographic examination was performed in 51 consecutive patients with SSS who received an initial pacemaker from January 1979 to September 1989 and were free of any structural heart disease at the time of implant. Atrial or dual chamber pacemakers were implanted in 21 patients (Group I) and ventricular pacemakers in 30 (Group II). The two groups were matched for age, gender, paced rate, blood pressure and duration of pacing. After a mean follow-up of 64 +/- 34 months, congestive heart failure developed in one patient in group I and 3 in Group II. Patients in group II, had larger left atrium (41 +/- 5 vs 37 +/- 6 mm, p < 0.05) and left ventricular end-diastolic volume (64 +/- 18 vs 54 +/- 12 ml/m2, p < 0.01) but similar left ventricular end-systolic volume (27 +/- 12 vs 24 +/- 9 ml/m2, p = NS), ejection fraction (59 +/- 10 vs 57 +/- 8%, p = NS), left ventricular mass (84.8 +/- 31 vs 85.6 +/- 29.2 gm/m2, p = NS), meridian end-systolic wall stress (48.3 +/- 22.1 vs 49.8 +/- 25 Kdynes/cm2, p = NS) and wall stress/end-systolic volume ratio (1.27 +/- 0.94 vs 1.42 +/- 0.59, p = NS). Pacing mode does not appear to influence left ventricular systolic function in patients with SSS.

Ventricular tachycardia with left bundle branch block morphology in the absence of ischaemic heart disease--clinical and electrophysiological observations.

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.

Atrial contribution to left ventricular filling in mitral stenosis: effects of balloon mitral valvuloplasty.

Doppler echocardiographic contribution of atrial systole to left ventricular filling (AC) was studied in 20 patients with mitral stenosis and compared with that obtained from 15 matched controls in a prospective study. AC in mitral stenosis as a percentage of total filling volume was 8 +/- 2.8% compared to 12.5 +/- 3.3% in control subjects (p < 0.001) and was weakly correlated to diastolic filling period (r = -0.45), mitral valve orifice resistance (r = -0.36) and heart rate (r = 0.36). An increase in mitral valve orifice area following balloon mitral valvuloplasty (0.78 +/- 0.12 to 1.72 +/- 0.4 cm2, p < 0.0001) resulted in an increase in AC to near normal values (8 +/- 2.8% to 12.5 +/- 3.8%, p < 0.001) coupled with an increase in cardiac index and a significant decrease in diastolic filling period and left atrial size. In conclusion, AC in young patients with severe mitral stenosis is decreased proportionately less than that reported in the older patients, is weakly correlated to mitral orifice resistance and normalises following a successful mitral valvuloplasty.

Comparative clinical and electrophysiologic effects of adenosine and verapamil on termination of paroxysmal supraventricular tachycardia.

The efficacy and electrophysiologic effects of adenosine and verapamil in termination of paroxysmal supraventricular tachycardia (SVT) were compared in 18 patients (age 18-48 years, mean 33 +/- 9 years) with recurrent sustained and inducible SVT. Ten patients had atrioventricular nodal reentrant tachycardia (AVNRT) and 8 had atrioventricular reentrant tachycardia involving a retrograde accessory pathway (cycle length of SVT 280-360 msec; mean 315 +/- 20 msec). Each patient served as his own control. After induction of SVT, adenosine was administered first (6 mg i.v. bolus). If the tachycardia was not terminated, a bolus of 12 mg was given. Ten minutes later, verapamil (5 mg i.v. over 30 sec) was administered after reinduction of SVT. If the tachycardia was not terminated, a 5 mg dose was repeated every 5 minutes upto 20 mg. Adenosine terminated the SVT in 16 cases (6 mg - 7 patients, 12 mg - 9 patients). Verapamil was effective in 11 patients (5 mg - 6 patients, 10 mg - 4 patients, 15 mg - 1 patient, 20 mg - nil). The overall efficacy of adenosine (89%) was significantly greater than that of verapamil (61%; p < 0.05). Adenosine terminated the tachycardia more quickly than verapamil (mean 24 +/- 11 sec versus 142 +/- 40 sec; p < 0.01). Termination of tachycardia by both drugs was related to antegrade block of the atrioventricular node in all patients except one with AVNRT in whom adenosine blocked the retrograde fast pathway. Ventricular premature beats were seen transiently in 5 patients following adenosine. Transient side effects such as flushing, burning and chest pain were frequently observed with adenosine and correlated with the termination of tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Amlodipine monotherapy in chronic stable angina.

The efficacy and safety of amlodipine was evaluated in 20 patients with stable exertional angina. Patients with > or = 3 anginal attacks per week in the placebo run-in phase were admitted into a 4 weeks active treatment phase. Amlodipine was administered at a starting dose of 5 mg once daily at bed time, which could be adjusted after 2 weeks to 10 mg once daily if the patient continued to have even a single anginal attack/week. Four weeks of treatment with amlodipine produced a significant (p < 0.05) reduction from baseline in both the mean (+/- SE) number of anginal attacks/week (from 13.3 +/- 1.5 to 1.6 +/- 0.5) and the mean (+/- SE) number of isosorbide dinitrate tablets consumed per week (12.1 +/- 1.5 to 2.6 +/- 0.8). Eighty three percent of patients required an increase in dose to 10 mg daily. No significant change in heart rate, blood pressure, ECG and laboratory results were observed. One patient was withdrawn because of deteriorating angina and sinus tachycardia secondary to beta blocker withdrawal. Worsening of ankle odema was reported in 2 (10%) patients, which was tolerated and disappeared on completing therapy. Thus amlodipine is safe and effective when used as monotherapy in the treatment of chronic stable angina.

Long term performance of atrial leads.

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.

Amlodipine monotherapy in mild to moderate hypertension.

The efficacy and safety of amlodipine was evaluated in 20 patients of mild to moderate hypertension in a single blind, placebo controlled, noncomparative study. Patients with a baseline diastolic blood pressure of > 90 and < 115 mmHg while on placebo were admitted to a 4 week active treatment phase. Amlodipine produced a significant (p < 0.05) reduction in mean systolic (177 mmHg to 145 mmHg) and diastolic blood pressure (106 mmHg to 84 mmHg) after 4 weeks treatment in all patients. 95% of the patients had their diastolic blood pressure reduced to < or = 90 mmHg by the end of the study period. There was no significant change in heart rate or in the laboratory parameters with amlodipine therapy. Seven patients reported mild to moderate adverse events which did not require discontinuation of therapy. This combination of efficacy and tolerability, together with convenience of once daily dosing, should ensure the usefulness of amlodipine in the treatment of hypertension.

Laser assisted balloon angioplasty in lower extremity occlusive disease.

Percutaneous transluminal laser angioplasty was used as an adjunct to balloon angioplasty in 36 occluded lower extremity artery segments in 32 patients. Indications for intervention were severe claudication in 25 (78.1%) and rest pain or gangrene in 7 (21.9%) patients. Neodymium-yttrium-aluminium-garnet laser heated probe was used to recanalize the iliac artery in 19, femoral artery in 9, both iliac and femoral arteries in 2, and popliteal and tibial arteries in 2 patients. Patients with successful laser recanalization underwent balloon angioplasty to further widen the lumen. Initial angiographic success was achieved in 28 (87.5%) patients with recanalization of 32 (88.9%) of 36 occlusions. Three patients had extra-axial catheter/guide wire passage and 1 patient had acute thrombosis of the recanalized artery which was successfully reperfused by thrombolytic therapy. At discharge the Doppler ankle-arm pressure index had increased from 0.46 +/- 0.15 to 0.84 +/- 0.12 (p < 0.001) in 29 patients with recanalized arteries. There was marked clinical improvement in these patients. On 6-47 (mean = 23.4 +/- 7.5) months follow up of 28 successfully treated patients 26 (92.9%) showed sustained clinical improvement. Thus laser assisted balloon angioplasty appears to be a safe and useful adjunct in recanalization of lower extremity occlusive disease.

Balloon dilatation of native coarctation of aorta in infancy: immediate and follow up results.

We attempted balloon dilatation of native coarctation of aorta in 11 consecutive neonates and infants (age range 28 days-12 months, mean 4.6 +/- 4 months, all males) presenting with congestive heart failure. The peak to peak aorto-aortic systolic pressure gradient fell from 60 +/- 21 mmHg to 13 +/- 7 mmHg (range 0-30 mmHg) (p < 0.001). The diameter of coarcted segment increased from 2.5 +/- 0.65 mm (range 2-3.4 mm) to 5.4 +/- 0.9 mm (range 4-6.4 mm) (p < 0.001). No patient required surgical intervention. The peak instantaneous aorto-aortic systolic Doppler pressure gradient at 17.5 +/- 8.8 months (range 2-21 months) did not show any significant change (mean 17.5 +/- 8.89 mmHg range 0-30 mmHg). All patients except one showed improvement in congestive heart failure. None developed restenosis. On the basis of this experience we recommend that balloon dilatation of native coarctation of aorta in infants in congestive heart failure is a safe and effective procedure.

Endomyocardial biopsy--its evaluation in cardiac disorders.

Endomyocardial biopsies (EMBs) of 47 patients with various cardiac disorders were analysed. Clinically 26 patients were diagnosed as having dilated cardiomyopathy (DCM), 9 myocarditis, six restrictive heart disease and six as Duchenne muscular dystrophy. EMB showed normal histological picture in six cases of DCM and findings consistent with DCM in rest of the twenty cases. None of these biopsies showed evidence of myocarditis. Diagnosis of myocarditis could be confirmed on EMB only in three out of nine clinically diagnosed cases. Cases with restrictive heart disease showed normal biopsy in two, infarction in one, findings consistent with endomyocardial fibrosis in one and amyloidosis in two cases. EMB on six cases of Duchenne muscular dystrophy showed nonspecific histological changes. To conclude, in this series, cases of DCM did not show evidence of underlying myocarditis in endomyocardial biopsies.

Two-dimensional echocardiographic diagnosis of subaortic aneurysm.

Subaortic aneurysms are uncommon and most cases have been reported among black Africans. The present report relates to our experience with three patients having subaortic annular aneurysms, two of congenital origin and one following infective endocarditis of the aortic valve. The role of transthoracic 2- dimensional echocardiography in the diagnosis is emphasized.

Transcatheter ablation of ventricular tachycardia arising from right ventricular outflow tract.

Two patients with recurrent episodes of symptomatic, sustained monomorphic ventricular tachycardia (VT) resistant to medical therapy underwent catheter ablation for the relief of VT. One patient had arrhythmogenic right ventricular dysplasia while the other had no structural heart disease. The VT had left bundle branch block morphology with normal axis in both the patients. The cycle length during VT was 260 msec and 270 msec respectively. Site for ablation was guided by pacemapping and the target site was identified in the right ventricular outflow tract in both the patients. Two cathodal shocks of 200 J in the first patient and one shock of 200 J in the second patient resulted in abolition of the arrhythmia. At repeat electrophysiologic testing at 7 days in the first patient and at 8 months in the second, VT was not inducible despite three extrastimuli from two right ventricular sites. Over a follow up of 24 and 26 months respectively, there has been no recurrence without any antiarrhythmic therapy. There were no acute or long term complications. In conclusion, catheter ablation offers a cure in patients with right ventricular tachycardia resistant to antiarrhythmic drugs.