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Biomedical subjects

H G Mond

Publications and source records attributed to H G Mond.

At least 19 recordsLinked to original sources
PubMed1995

Atrial pacing leads: the clinical contribution of steroid elution.

Although the original atrial pacing leads were passive fixation and J shaped for right atrial appendage placement, the subsequent development of the active fixation screw-in lead found favor because of a perceived low incidence of lead dislodgment and a wider selection of atrial pacing sites. A bipolar atrial lead study was undertaken to compare the long-term atrial implant data in 215 patients. Study leads comprised one passive fixation, steroid-eluting lead (Medtronic CapSure SP, 119 patients) and three nonsteroid-eluting leads; two active fixation (Medtronic BISPING model 4058, 30 patients; and Telectronics ACCUFIX model 330-801, 44 patients) and one passive fixation (Telectronics ENCOR model 330-854, 22 patients). Bipolar atrial voltage stimulation thresholds and electrograms were measured using the Telectronics META DDDR immediately postimplantation, and at 1-, 3-, 6-, 12-, and 18-month follow-up. There were 135 males and the mean age 68 years. The incidence of lead dislodgment was 4% for active fixation and 2% for passive fixation. All nonsteroid leads showed a typical rise in stimulation threshold with the highest being the ACCUFIX followed by the BISPING and ENCOR. The steroid-eluting CapSure SP, however, demonstrated a flat response with 98% of leads at 18 months having a value < or = 1.3 volts allowing voltage programming to 2.5 volts (2:1 safety ratio). Telemeted electrograms showed no differences for all leads at all visits. For low voltage atrial pacing with a low incidence of dislodgment and satisfactory atrial sensing, the steroid-eluting passive fixation lead is superior to all nonsteroid-eluting leads.

Aged↗
PubMed1991

Ventricular dysfunction following direct-current shock atrioventricular junction ablation.

Catheter-induced His bundle ablation for refractory supraventricular arrhythmias is most commonly performed with direct-current shock energy of 200-300 joules. The high energy pulse delivered by direct-current shock produces a lesion in the atrioventricular node by fulguration, with the residual energy being dissipated as a pressure wave. The effect of direct-current shock His bundle ablation on global and regional ventricular function was assessed in 14 consecutive patients by radionuclide ventriculography performed before and after ablation and again three months later. All studies were performed with ventricular pacing at 110 bpm. Global left ventricular ejection fraction was found to be significantly reduced at the three month study (0.43 +/- 0.03 vs 0.50 +/- 0.03, pre ablation, p = 0.02). A significant reduction in wall-motion score was also seen in six of the seven patients who had normal wall motion in pacing rhythm prior to ablation. Deterioration was mainly seen at the left and right ventricular apices. The observed reduction in ventricular function that follows direct-current shock His bundle ablation may result from myocardial damage from electro-coagulation or from barotrauma and supports continued investigation into alternative, less traumatic energy sources for the procedure.

Adult↗
PubMed1988

Short- and long-term results of transvenous catheter ablation of the atrioventricular conduction system.

Twenty-two patients with refractory supraventricular arrhythmias were treated by catheter-delivered high-energy shocks to the atrioventricular conduction system. All patients had a minimum follow-up period of six months (mean +/- SD, 15 +/- 9 months), at which time 21 of the 22 patients were free of symptoms and required no antiarrhythmic therapy. Permanent pacemakers were implanted in all patients. These results show that transvenous ablation or modification of atrioventricular conduction is a safe and effective technique to treat a wide range of supraventricular arrhythmias, and obviates the need for open-heart surgery for the interruption of atrioventricular nodal conduction.

Adolescent↗
PubMed1985

Ventricular tachycardia and sudden death in myotonic dystrophy: clinical, electrophysiologic and pathologic features.

A 37 year old man who presented with a cardiomyopathy, conduction defects and atrial and ventricular arrhythmias was found to have the neuromuscular manifestations of myotonic dystrophy. Despite implantation of a permanent cardiac pacemaker, antiarrhythmic drug therapy and antiarrhythmic surgery, sudden death occurred. The results of electrophysiologic studies, coronary arteriography and pathologic findings are described. This case confirms previous observations that ventricular arrhythmias, in addition to atrial arrhythmias and conduction disturbances, are cardiac manifestations of myotonic dystrophy and can lead to sudden death.

Adult↗
PubMed1981

The malfunctioning pacemaker system. Part I.

The success of an implanted cardiac pacemaker is dependent upon the establishment of a harmonious relationship between the artificial pacemaker and the human receiver. Failure of a pacemaker system may arise from an electronic or mechanical defect within the pacemaker, a physiologic problem, or from a poor relationship between the normal function of both. Such malfunctions may necessitate the repair, replacement, or repositioning of a pacemaker component or removal of a source of external interference. True pacemaker malfunctions must be clearly distinguished from pseudo-malfunctions, where there is no pacemaker system defect. These situations may, variously, require the repair of faulty testing equipment, reassessment of falsely interpreted test data, or treatment of the patient for an unrelated disorder. This paper outlines a system for investigating patients with suspected pacemaker malfunction. For simplicity, only malfunctions associated with the ventricular inhibited pacing system will be discussed.

Cardiac Pacing, Artificial↗
PubMed1979

The use of balloon-tipped electrodes for permanent cardiac pacing.

A new balloon-tipped ventricular endocardial electrode for permanent artificial cardiac pacing is described. Following transvenous insertion of the electrode to the right ventricular apex, the distal balloon is inflated with contrast material in order to wedge the electrode tip between or beneath trabeculae and prevent displacement. fifty-nine electrodes were implanted, including a second generation type incorporating a wedge tip as well as the balloon. The incidence of displacement was 17% with 10% of cases being early, and 7% late. Early in the series, 50% Urografin was used to inflate the balloon and this resulted in premature deflation and early electrode displacement in two of the nine patients. When the concentration of Urografin was reduced, the balloon remained inflated for a longer period and the incidence of early displacement was reduced to 8%. However, there was still a late displacement of 8%. Only one wedge-tipped balloon electrode displaced. This electrode had a faulty sealing mechanism and the balloon could not be adequately inflated. There was a 3% incidence of early and a 3% incidence of late threshold problems with the electrode. However, name of the wedge-tipped balloon electrodes exhibited this problem. It was concluded that this new electrode did not fulfill its objectives. The total electrode failure rate, including displacements and episodes of high threshold was approximately 24%.

Aged↗
PubMed1978

The diagnosis of right ventricular perforation by an endocardial pacemaker electrode.

The diagnosis of right ventricular perforation by an endocardial pacemaker electrode should be suspected when failure of pacing occurs without electrode displacement. Although a number of changes occur on the standard electrocardiogram (ECG), none of these are diagnostic. The intracardiac electrogram performed during electrode withdrawal is not only diagnostic of perforation but can also aid in electrode positioning. Two case reports highlight these changes in the intracardiac electrogram. The first case also illustrates that, with electrode perforation, the ability to sense the intrinsic intracardiac electrical activity may be retained.

Aged↗