James D. Maloney

Permanent pacemaker infections: Characterization and management

From January 1974 to June 1980, a total of 46 patients were treated for infections involving permanent pacing systems. Demographic characteristics, types of infecting organisms, specific clinical features, significance of an infected foreign body and various medical and surgical treatment methods are described. Likely infecting organisms depend on the mode of presentation and the time course of the infection. Optimal treatment for the large majority of patients requires removal of the entire infected pacing system. In a subgroup of patients, a short course of antibiotic therapy followed by one stage surgery involving implantation of a new pacing system and concurrent explanation of the infected pacemaker was used safely with excellent results.

Hemodynamic benefits of atrioventricular sequential pacing after cardiac surgery

The hemodynamic effects of atrioventricular (A-V) sequential pacing were assessed and compared with those of ventricular and of atrial pacing in 10 patients with and without heart block after cardiac surgery. Ventricular pacing alone was either hemodynamically detrimental or of no benefit in six of the eight patients who initially had sinus or accelerated junctional rhythms. Atrial pacing alone produced significant improvement in cardiac output in all patients who were not pacemaker-dependent. However, five of the eight patients with intact A-V conduction had further increases in cardiac output through A-V sequential pacing at shorter than intrinsic A-V intervals. Optimal A-V intervals for maximal cardiac output could be identified in all patients and varied widely. Significant changes in cardiac output occurred with relatively small diviations in the A-V interval. In selected patients after cardiac surgery, temporary A-V sequential pacing is a workable and valuable adjunctive form of hemodynamic support and is preferable to ventricular or atrial pacing.

Etiology of right bundle-branch block pattern after surgical closure of ventricular-septal defects☆

An incidence of 60 per cent of postoperative RBBB in the ECGs and available VCGs of 26 patients with isolated muscular VSD repaired was noted after ventriculotomy. In the 38 patients with VSDs near the membranous septum who underwent repair via the tricuspid valve, the incidence of postoperative RBBB was 44 per cent. Results suggested that either ventriculotomy or injury to the right bundle near the VSD can cause RBBB after surgical closure of the defect. Changes in the initial 0.02 second electrovectocardiographic forces in patients with postoperative RBBB were thought to result from central injury to the specialized conduction tissue supplying the interventricular septum. Peripheral RBBB, therefore, could be separated from central RBBB, by the appearance of the initial electrovectorcardiographic forces. For detection of these changes in initial forces, both the ECG recorded at 50 mm. per second and the Frank VCG were useful.

Thyroxine therapy in hypothyroid patients undergoing coronary revascularization: A retrospective analysis.

Excerpt Hypothyroid patients with disabling angina pectoris present a difficult problem in clinical management (1). Because rapid thyroid hormone replacement can aggravate a pre-existing anginal sy...

Open clinical studies at a referral center: Chronic maintenance tocainide therapy in patients with recurrent sustained ventricular tachycardia refractory to conventional antiarrhythmic agents

Chronic maintenance tocainide therapy was effective in controlling symptomatic, recurrent ventricular tachycardia in 11 of 15 patients. Patients were selected for tocainide therapy on the basis of refractoriness to conventional antiarrhythmic agents and responsiveness to the intravenous administration of lidocaine. Side effects were frequent but could usually be managed by taking the drug with meals or by more frequent administration of smaller doses. Survival, frequency of symptomatic tachycardia, frequency of asymptomatic ventricular tachycardia, and tolerance of the therapeutically effective dosage were the criteria used to assess therapeutic effectiveness. Factors common to the response group included primary and secondary Q-T prolongation before therapy, a paradoxical increase in ventricular ectopic activity with quinidine-like medications, and shortening of the Q-T interval with maintenance tocainide therapy. These factors may prove to be useful in identifying the patients who are most likely to benefit from chronic maintenance tocainide therapy.

Early Follow‐Up of Lead Performance in Atrioventricular Sequential Systems

Recent developments in pacemaker technology led us to report our initial and follow‐up assessment of atrioventricular (A‐V) sequential systems in 50 consecutive patients. Primary indications for pacing were sinus node dysfunction or A‐V block. Leads were introduced through the subclavian vein. Atrial J‐tined leads (27 silicone, 19 urethane) were positioned in the atrial appendage or stump in 46 patients, and coronary sinus or Bisping leads were placed in 4 patients; all 50 patients had tined ventricular leads. A Medtroric 5992 generator was placed in 35 patients and an Intermedics 259–01 generator in 15. Median implantation time was 105 minutes. Complications requiring reoperdtion in 409 patient‐nnonths of follow‐up included lead retraction (one patient), phrenic nerve stimulation (one), pseudofracture (one), and atrial lead‐induced “cross talk” (one). Monthly telephone transmission confirmed atrial capture in 35 patients and loss of capturein 1; the remainder had no identifiable P wave. Ventricular capture was confirmed in all. Postimplant and follow‐up checks showed good stability of lead positions. We conch de that these systems have a low incidence of problems in short‐term followup. (PACE, Vol. 5, September‐October, 1982)

Concealed retrograde bypass tracts and enhanced atrioventricular nodal conduction: An unusual subset of patients with refractory paroxysmal supraventricular tachycardia

The clinical and electrophysiologic features of eight patients with unusually rapid, medically refractory paroxysmal supraventricular tachycardia are described. Exercise induction of tachycardia and functional bundle branch block patterns during tachycardia were common. Tachycardia resulted from anterograde enhanced atrioventricular nodal conduction combined with retrograde conduction by a concealed left atrial-left ventricular accessory pathway producing rates ranging from 200 to 300 beats/min. Management and late follow-up study were characterized by generally unsuccessful electrophysiologic-pharmacologic testing and inconsistent rhythm control with continued drug therapy. Three patients underwent successful surgical interruption of the concealed accessory pathway, with elimination of recurrent tachycardias. These patients represent a unique subgroup with an identifiable electrophysiologic basis for unusually rapid tachycardias, potentially benefiting from invasive study and aggressive therapy.

Long-term endocardial atrial pacing in children with postoperative bradycardia-tachycardia syndrome and limited ventricular access

Permanent pacing in children, including those with postoperative bradycardia-tachycardia syndrome has been compromised by the availability of pulse generators, electrode leads and implantation techniques designed for the adult patient. Recent technologic improvements and simplified implantation techniques have reduced many of these barriers and have made endocardial as well as epicardial ventricular pacing more feasible. However, in some children, ventricular pacing may be impeded by anatomic abnormalities due to congenital anomalies or prior cardiac operations. In these instances, endocardial atrial pacing may provide an alternative therapeutic approach in selected patients. This report describes the use of endocardial atrial demand pacing in four children with postoperatively bradycardia-tachycardia syndrome and restricted ventricular access. This approach controls symptomatic bradycardia, helps prevent and convert paroxysmal intraatrial tachycardia and overcomes the problems of limited ventricular access.

Clinical Evaluation of a Sutureless Cardiac Pacing Lead: Chronic Threshold Changes and Lead Durability

Chronic threshold changes and durability of the Medtronic 6917 sutureless cardiac pacing lead were evaluated in 100 consecutive patients. A bipolar pacing system was established in each patient. Lead failure occurred in 4 patients; all failures resulted from exit block or loss of adequate contact between electrode and myocardium. Electrode fracture or loss of lead insulation was not observed. Fifty patients had replacement of the pulse generator 27.4 +/- 1.8 months after implantation. Long-term stimulation threshold voltage was about 2.5 times greater and current was about 3.5 times greater than values obtained at initial implantation, yet they continued to permit safe and effective cardiac pacing.

Initial and Early Follow-up Assessment of the Clinical Efficacy of a Multiparameter-Programmable Puise Generator

Recent advances in pacemaker technology have produced noninvasively multiparameter‐programmable puise generators that have the potential for resolving complications that result from the pacing system and forproviding a mechanism whereby adjustments can be made for the specific needs of a patient without corapromising reliability and longevity. These applications were assessed by analyzing the initial indications, clinical efficacy, and reliability in 100 consecufive patients who received a multiparameter‐program‐mable puJse generator. Data analysis showed that 78% of the 100 patients had changes in rate programmed, 16% in pufse width, and 5% in sensitivity. Program‐mability was utilized for voJtage amplitude (one patient) but was not utilized for hysteresis and refractory period. Although progrtimming changes (rate and pulse width) generally could have been accomplished with simpler units, program‐mability for sensitivity made it possible to solve pacemaker problems in five patients and clearly eliminated the need for reoperation in two patients. The compact size of the multiparameter‐programmable pulse generator has allowed its use in patients in the pediatric age group, patients with a small frame, and patients with a major concern about cosmetic appearance. Programming sensitivity for proper sensing of the atrial signal allows use of the multiparameter‐programmable pulse generator as an atrial pacemaker. This was done in one pediatric patient who also benefited from suppression of atrial overdrive. There have been no episodes of spurious programming. Reliabitity has not been sacrificed by the increased complexity of this unit. If preimplant criteria for use of a multiparameter‐program‐mable puise generator are too sfrict, this may limit its potential therapeutic value because the need for its flexible characleristics is unpredictable.