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Biomedical subjects

M Khalilullah

Publications and source records attributed to M Khalilullah.

At least 55 records · Page 3Linked to original sources
PubMed1983

Selective blockade of retrograde fast pathway by intravenous disopyramide in paroxysmal supraventricular tachycardia mediated by dual atrioventricular nodal pathways.

Electrophysiological effects of 2 to 2.5 mg/kg iv disopyramide were studied in 10 patients with dual nodal pathways who used a slow pathway for anterograde and a fast pathway for retrograde conduction during paroxysmal supraventricular tachycardia (mean cycle length 308.5 +/- 37 ms; range 260-370 ms). Disopyramide terminated the tachycardia in six cases by production of ventriculoatrial block in five and by sinus overdrive in one. In the remaining four patients cycle length of the paroxysmal supraventricular tachycardia increased significantly from 270 +/- 8 ms to 377.5 +/- 28 ms. In all 10 patients disopyramide depressed retrograde fast pathway conduction manifest by an increase in mean ventricular paced cycle length producing ventriculoatrial block from less than or equal to 296.5 +/- 25 ms to 358 +/- 60 ms, and increase in retrograde fast pathway effective refractory period from less than or equal to 246 +/- 34 ms to 325 +/- 36 ms; the drug abolished ventriculoatrial conduction in two cases. Anterograde slow pathway and fast pathway conduction properties were unchanged after disopyramide (atrial paced cycle length producing AH block 292 +/- 30 to 306.5 +/- 30 ms; effective refractory period of anterograde fast pathway less than or equal to 274 +/- 56 to 284 +/- 44 ms, before and after the drug, respectively) suggesting that anterograde conduction was not crucial either for sustainment or for failure to initiate paroxysmal supraventricular tachycardia after the drug. Paroxysmal supraventricular tachycardia could not be reinduced in six cases after disopyramide. In the other four the ventricular paced cycle lengths producing ventriculoatrial block (318 +/- 41 ms) and effective refractory period of retrograde fast pathway (320 +/- 28 ms) were shorter than the cycle length of reinduced paroxysmal supraventricular tachycardia (367.5 +/- 35 ms) allowing perpetuation of the tachycardia. We conclude that disopyramide breaks atrioventricular nodal re-entrant tachycardia by specific blockade of the retrograde fast pathway though the effect on anterograde atrioventricular nodal conduction is variable.

Adult↗
PubMed1980

Ajmaline in WPW syndrome: an electrophysiologic study.

Six patients including three females with WPW syndrome (three with type A and three with type B) presenting with recurrent paroxysmal tachyarrhythmia were subject to electrophysiological studies. Apart from basal parameters, rapid atrial and ventricular pacing was done which confirmed electrophysiological characteristics of bundle of Kent operation. A single intravenous bolus of ajmaline 50 mg. was effective in blocking the bundle of Kent in all patients within 30 seconds of injection with the effect persisting for 15 minutes in one and from 25 to 60 minutes in the others. The most dramatic effect was prolongation of the HV interval with normalization of QRS complex with a marginal effect on the AH interval. The drug was also effective in breaking narrow QRS tachycardia in two patients and broad QRS tachycardia in one patient. Long-term oral therapy with ajmaline has proved effective in preventing recurrent tachyarrhythmias. We conclude that ajmaline is specifically effective and safe in the treatment of the WPW syndrome.

Adult↗
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↗