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Biomedical subjects

J Camm

Publications and source records attributed to J Camm.

7 recordsLinked to original sources

Ebstein's anomaly in association with anomalous nodoventricular conduction. Pre-operative and intra-operative electrophysiological studies.

A 13 year old girl with Ebstein's anomaly was investigated for refractory paroxysmal tachycardias and ventricular pre-excitation. Intracardiac electrophysiological studies demonstrated that ventricular pre-excitation was due to conduction in an anomalous nodo-ventricular pathway. Tachycardia occurred as a result of re-entry within the A-V node with pre-excitation during tachycardia due to conduction in the nodo-ventricular pathway. These tachycardias were controlled initially by medical therapy but because of increasing frequency of attacks, occasionally requiring D.C. conversion, further electrophysiological studies and epicardial mapping were undertaken. The epicardial surface of the right ventricle and right atrium were mapped during tachycardia. The results of the studies confirmed that a direct anomalous atrio-ventricular pathway was not present and that re-entrant tachycardia did not involve an accessory pathway of this type. A rapid atrial pacing system was implanted and paroxysmal tachycardias have been successfully controlled.

Action Potentials

The effect of intravenous disopyramide phosphate on recurrent paroxysmal tachycardias.

1 Reccurent paroxysmal atrial, atrioventricular and ventricular tachycardias in 50 patients without acute coronary insufficiency, heart failure or metabolic abnormlity were treated with disopyramide phosphate in a dose of 2 mg/kg body weight infused over 5 min. 2 Conversion to sinus rhythm within 10 min of the completed infusion occurred in 10 of 14 (71%) patients with paroxysmal 'lone' atrial fibrillation, 3 of 7 (43%) patients with paroxysmal atrial flutter, 6 of 9 (67%) patients with paroxysmal atrial tachycardia, 5 of 9 (56%) patients with paroxysmal atrioventricular tachycardia associated with the Wolff-Parkinson-White syndrome and 8 of 11 (73%) patients with paroxysmal ventricular tachycardia. 3 Side effects: significant systemic hypotension in 3, high grade AV block in 1, an increased ventricular response producing symptoms in 4, post conversion asystole in 1 land sinus bradycardia in 2. 4 The anti-arrhythmic effect and arrhythmogenic side effects may be related to both the direct membrane stabilizing effect and the anticholinergic effect of disopyramide.

Atrial Fibrillation

Intravenous disopyramide phosphate and ventricular overdrive pacing in the termination of paroxysmal ventricular tachycardia.

Both antiarrhythmic drugs and bursts of rapid ventricular pacing provide alternatives to DC cardioversion for the treatment of paroxysmal ventricular tachycardia. This report considers the individual and combined success of burst ventricular pacing and intravenous disopyramide phosphate in the tretment of 11 examples of paroxysmal ventricular tachycardia. Rapid ventricular pacing, at a rate of up to 50 beats/min faster than the tachycardia rate terminated 7 of the tachycardias. Intravenous disopyramide resulted in increased tachycardiac cycle length (342 +/- 34 ms-385 +/- 56 ms), increased QRS complex width (147 +/- 42 ms-180 +/- 41 ms) and termination of 8 the tachycardias. The remaining 3 tachycardias could be terminated by bursts of ventricular pacing following the infusion of disopyramide. Of these, 2 could not be terminated prior to disopyramide. The use of both techniques allowed the extinction of all 11 tachycardias and prevented the need to proceed to DC conversion.

Adult

Improvement in exercise haemodynamics by isosorbide dinitrate in patients with severe congestive cardiac failure secondary to ischaemic heart disease.

Seven patients with severe chronic congestive cardiac failure secondary to ischaemic heart disease performed submaximal supine exercise before and after 5 mg sublingual isosorbide dinitrate at the time of cardiac catheterisation. Exercise before isosorbide dinitrate produced a poor response in left ventricular performance. After isosorbide dinitrate this response was significantly improved. Compared with the control exercise period, cardiac index increased from mean 2.6 to 3.1 1/min per m2 (P less than 0.0025), stroke volume index from mean 22 to 27 ml/m2 (P less than 0.0025), and left ventricular stroke work index from mean 21 to 30 g m/m2 (P less than 0.01). Mean left ventricular filling pressure fell from 37 to 26 mmHg (P less than 0.01). Although isosorbide dinitrate reduced left ventricular filling pressure at rest from mean 26 to 17 mmHg (P less than 0.005), there was no significant change in mean cardiac index or stroke volume index, while left ventricular stroke work index decreased from mean 29 to 22 g m/m2 (P less than 0.05). Isosorbide dinitrate effectively reduces left ventricular filling pressure in the resting patient with congestive cardiac failure but produces a more comprehensive improvement in left ventricular performance during exercise.

Aged

Effects of disopyramide on electrophysiological properties of specialized conduction system in man and on accessory atrioventricular pathway in Wolff-Parkinson-White syndrome.

Seven patients with normal specialized conduction system and three patients with the Wolff-Parkinson-White (WPW) syndrome were studied using programmed stimulation of the heart before and after the administration of intravenous disopyramide. The principal effect of this drug was to prolong the effective refractory period of the atria and ventricles, and to prolong the effective refractory period of the anomalous pathway in the WPW syndrome. In addition, it prolonged the conduction time in the anomalous pathway in the WPW syndrome. These findings suggest that disopyramide would be a useful and safe drug in the management of certain atrial and ventricular arrhythmias and in the management of the Wolff-Parkinson-White syndrome with atrial fibrillation.

Adolescent