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Biomedical subjects

M Khalilullah

Publications and source records attributed to M Khalilullah.

At least 37 records · Page 2Linked to original sources
PubMed1987

Percutaneous transluminal balloon angioplasty of the aorta in patients with aortitis.

Four patients with aortitis and stenotic lesions of the aorta were successfully treated by percutaneous transluminal balloon angioplasty. The peak systolic gradient across the constrictions decreased from 82.5 +/- 35.7 to 37.5 +/- 18.5 mm Hg immediately after dilatation. Repeat angiography in the first three patients performed 2 months later showed a further decrease in the gradient to 13.8 +/- 9.5 mm Hg. There were no complications during or after the procedure, and all the patients have shown remarkable symptomatic relief during the follow-up.

Adolescent↗
PubMed1979

Unidirectional complete heart block.

Forty-two patients with complete heart block were subjected to electrophysiological studies wherein apart from localization of the site of the conduction defect, ventricular pacing was done to assess ventriculo-atrial (VA) conduction and concealed ventriculo-nodal (VN) conduction. There was evidence of retrograde conduction in the presence of orthograde CHB in 22 patients (52.4 per cent). Fifteen patients (35.7 per cent) had VA conduction and seven (16.6 per cent) had concealed VN conduction. In patients with supra-Hisian CHB, three of the nine patients had VA conduction while of the 11 patients with intra-Hisian CHB, six had retrograde conduction (four with VA and two with concealed VN conduction). In the infra-Hisian CHB group, of the 22 patients, eight had VA conduction and five had concealed conduction. Incremental ventricular pacing induced VA Wenckebach periods at VPR from 110 to 133/minute with a VA interval of 110 to 130 msec. In view of the induction of Wenckebach VA periods, the recording of retrograde H potentials in some cases, and relatively long VA conduction time, it is surmised that retrograde conduction in the presence of orthograde CHB takes place through the AV conduction system.

Adult↗
PubMed1978

Left atrial rhythm in man: an experimental study.

Ten patients with atrial septal defect of the secondum variety undergoing diagnostic haemodynamic study were subjected to electrical stimulation of the endocardium of the left atrium using a bipolar pacing electrode catheter. The polarity, frontal plane P wave axis and P wave configuration were analysed from ten scalar 12 lead electrocardiogram (ECG), recorded at 25-50 mm/sec during sinus rhythm and left atrial stimulation. While four patients demonstrated the "dome and dart" appearance of P waves in V1, nine out of ten patients revealed upright P waves in V1 during left atrial pacing; one patient showed inverted P waves in V1-V6. Four patients had negative "P" waves in L1 and only five of ten patients had inverted "P" waves in L1 and V6. All the criteria of left atrial rhythm were present in only one patient. It appears that the "P" waves change during left atrial pacing are variable and that the typical findings of left atrial rhythm are not obtained in all cases. This study was planned because trans-septal left atrial stimulation in the genesis of left atrial rhythm has not been widely reported.

Cardiac Catheterization↗
PubMedDate not supplied

Catheter ablation of retrograde fast pathway in patients with atrioventricular nodal reentrant supraventricular tachycardia.

Atrioventricular (AV) nodal reentrant tachycardia is a common cause of supraventricular tachycardia. The present study describes catheter ablation of this form of tachycardia in 23 patients using direct current shocks. The aim of ablation was to abolish conduction through the retrograde pathway while preserving the anterograde conduction. All patients had symptomatic, drug resistant, slow-fast variety of dual atrioventricular nodal reentrant tachycardia. Using the retrograde atrial activation in the His bundle catheter as the reference, the optimal ablation site was selected by positioning an electrode catheter to obtain atrial activation synchronous with or earlier than the atrial activation at the reference electrode. Shocks of 100-300 joules were delivered at this site resulting in blockade of retrograde conduction in all patients. Ventriculo-atrial conduction studied 24 hours after the procedure was still absent in 16, modified in 2 and resumed in 3 patients. Two patients developed permanent complete heart block and were given pacemakers. At repeat electrophysiologic study performed after 2-4 months in 10 patients, the supraventricular tachycardia could not be induced. The AH interval was 67 +/- 10 msec during control study and to 115 +/- 39 msec at restudy (p < 0.001). The ventriculo-atrial conduction was absent in 7 cases and had been modified in 1 case. Over a follow up period of 1-30 months (mean 10.8 +/- 7.1 mo) 17 patients (73%) remained free of the arrhythmia without medication or pacemaker. Three other patients were easily controlled with digoxin. Thus, catheter modification of AV node results in permanent cure of the AV nodal tachycardia in majority of patients.

Adolescent↗
PubMedDate not supplied

Role of transesophageal echocardiography during balloon mitral valvuloplasty.

Transoesophageal echocardiography (TEE) was performed during balloon mitral valvuloplasty (BMV) in 40 patients of rheumatic mitral stenosis, to assess its feasibility and additional benefits. The age range was 12-35 (mean 20 +/- 6) years. Patients were in an unsedated state and the procedure was tolerated by all without any complication. High resolution images of the interatrial septum and the puncture assembly were obtained which guided the septal puncture. In eight (20%) patients, puncture assembly had to be readvanced into superior vena cava and withdrawn down to obtain a satisfactory position for puncture. In 2 additional cases, the puncture assembly was redirected towards the fossa ovalis region under TEE guidance alone to obtain a successful septal puncture. TEE was not found useful in either negotiating the mitral valve or positioning the balloon catheter across it.

Adolescent↗
PubMedDate not supplied

Cross sectional echocardiographic left ventricular ejection fraction: method based variability.

Cross-sectional echocardiographic left ventricular ejection fraction (LVEF) by five different Methods (Teichholz, Area-length, single-plane Simpson, Bullet and Baran Formulae) was determined in 24 normal healthy volunteers (male-17, female-7, age range 16-80 years, mean 37 +/- 13) to assess the method-dependent variability in left ventricular volumes and LVEF. Although the Teichholz and Bullet methods gave somewhat higher values, there was no significant difference between LVEF determined by any of the methods (F = 0.16, p greater than 0.50). There was an a symmetrical distribution of LVEF in this normal group with an absolute mean positive skewness of 6 per cent (range 4-7 percent, coefficient of skewness = +0.43 to +0.87). A cut-off normal lower limit of LVEF at 50 per cent encompassed 88-100 per cent (mean 93.3) of subject population depending upon the method used. Similarly there was no significant difference between left ventricular volumes obtained by various methods. Therefore all the above five methods for quantitation of left ventricular global function are equally useful in clinical studies in patients with normal left ventricular geometry and in absence of segmental asynergy.

Adolescent↗
PubMedDate not supplied

Acute hemodynamic effects of different atrioventricular intervals in dual chamber pacemakers: is there an optimum atrioventricular delay.

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.

Adult↗
PubMedDate not supplied

Experience with recycled cardiac pacemakers.

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.

Adult↗
PubMedDate not supplied

Long term performance of silicone insulated and polyurethane insulated cardiac pacing leads.

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).

Adolescent↗