Nicholas P.D. Smyth

The NASPE*/BPEG** Generic Pacemaker Code for Antibradyarrhythmia and Adaptive‐Rate Pacing and Antitachyarrhythmia Devices

A new generic pacemaker code, derived from and compatible with the Revised ICHD Code, was proposed jointly by the North American Society of Pacing and Electrophysiology (NASPE) Mode Code Committee and the British Pacing and Electrophysiology Croup (BPEC), and has been adopted by the NASPE Board of Trustees. It is abbreviated as the NBC (for “NASPE/BPEC Generic”) Code, and was developed to permit extension of the generic‐code concept to pacemakers whose escape rate is continuously controlled by monitoring some physiologic variable, rather than determined by fixed escape intervals measured from stimuli or sensed depolarizations, and to antitachyarrhythmia devices including cardioverters and defibrillators. The NASPE/BPEC Code incorporates an “R” in the fourth position to signify rate modulation (adaptive‐rate pacing), and one of four letters in the fifth position to indicate the presence of antitachyarrhythmia‐pacing capability or of cardioversion or defibrillation functions.

The NASPE /BPEG Defibrillator Code

A new generic code, patterned after and compatible with the NASPE/BPEG Generic Pacemaker Code (NBG Code) was adopted by the NASPE Board of Trustees on January 23. 1993. It was developed by the NASPE Mode Code Committee, including members of the North American Society of Pacing and Electrophysiology (NASPE) and the British Pacing and Electrophysiology Croup (BPEC). It is abbreviated as the NBD (for NASPE/BPEC Defibrillator) Code. It is intended for describing the capabilities and operation of implanted cardioverter defibrillators (ICDs) in conversation, record keeping, and device labeling, and incorporates four positions designating: (1) shock location; (2) antitachycardia pacing location; (3) means of tachycardia detection; and (4) antibradycardia pacing location. An additional Short Form, intended only for use in conversation, was defined as a concise means of distinguishing devices capable of shock alone, shock plus antibradycardia pacing, and shock plus antitachycardia and antibradycardia pacing.

Management of Aortic Arch Aneurysm Using Profound Hypothermia and Circulatory Arrest

The cases of 9 patients with aneurysms involving the aortic arch, repaired under profound hypothermia (average, 15.5 degrees C) and circulatory arrest, are presented. Five patients underwent elective operation and 4, emergency operation. Arch resection and graft replacement were done in 7 patients. Two patients with infected pseudoaneurysms of the aortic arch received patch grafts. There were 2 deaths (22%) from coagulopathy and decerebration. Seven patients are alive and well 18 to 45 months following repair. The combination of profound hypothermia and circulatory arrest appears to be a promising solution to a difficult problem.

Transvenous removal of catheter emboli from the heart and great veins by endoscopic forceps.

Abstract A direct approach for removal of a catheter in the right atrium or great veins involves a major operation, with or without extracorporeal circulation. The use of standard endoscopic grasping forceps inserted into the right atrium via the right external jugular vein has been demonstrated to be both practical and rewarding. Fluoroscopic monitoring of the procedure with image amplification is essential. This safe, simple, and minimally traumatic approach should be used initially in all patients, and thoracotomy and atriotomy should be reserved for those patients in whom this first procedure fails.

Permanent Transvenous Atrial Pacing: An Experimental and Clinical Study

Abstract A J-shaped electrode catheter designed to fit in the right atrial appendage has been studied in the dog and in man. Catheter stability with occasional fixation may be expected in man. Displaced electrode catheters are easily replaced. Atrial stimulating thresholds were found to be higher than ventricular thresholds in the dog and in man. The P wave potentials were found to be low in man. Preoperative demonstration of normal atrioventricular (AV) conduction is essential before initiating atrial pacing. The P-S (P-wave-stimulated) standby principle simplifies the postoperative study of AV conduction by the use of external (indirect) overdrive to establish the rate at which AV block begins.

Permanent pervenous atrial pacing

Summary A “J” shaped electrode catheter designed to fit in the right atrial appendage has been studied in the dog and in man. The atrial electrode catheter is less stable than its ventricular counterpart and fixation may be expected only occasionally in man. Displaced electrode catheters are however easily replaced. In five patients atrial pacing could not be established. Stable atrial pacing was achieved in 14 of the 16 patients in whom it was established. P wave potentials are much lower in man than in the dog and are often marginal for the sensitivity of the presently available pulse generator. Atrial stimulating thresholds are higher than ventricular thresholds in the dog and in man, possibly due to less intimate contact with the endocardium than occurs in the ventricle. Preoperative study of A-V conduction is essential before initiating permanent atrial pacing to screen out the patients likely to develop A-V block at a later date. Postoperative study of A-V conduction is equally important to anticipate this complication in patients in whom atrial pacing has already been established. The P.S. (P wave stimulated) standby principle simplifies this since external overdrive can be used to check if the capacity of the A-V node for conduction is diminishing, as shown by a drop in the rate at which A-V block begins. This feature is not available with either P.I. (P wave inhibited) demand, or fixed rate atrial pacing.

Atrial Programmed Pacing

Early experience with a J‐shaped lead inserted transvenously into the right atrial appendage is reviewed in thirty‐one patients. Fifteen patients are still being followed with satisfactory atrial programmed pacing for five to (en years. A dislodgement rate of twenty percent led to the development of the “lined” J lead in the hope that better fixation would be achieved.

Permanent standby transvenous pacemaking.

There is currently increasing interest in the use of the permanent &dquo;standby&dquo; or &dquo;demand&dquo; pacemaker.1-8 Indications for the clinical use of this type of pacemaker include symptomatic sinus bradycardia, symptomatic intermittent heart block and atrial arrhythmia with varying conduction and Stokes-Adams syndrome. For the past 18 months, we have used an implantable transvenous endo-

Combined Gas and Heat Exchange in Extracorporeal Circulation.

Summary The advantages of combining oxygenation and heat exchange in a single unit are described. A modification of the vertical screen oxygenator is proposed in which the screens are replaced by plates, on the surface of which blood is filmed for oxygenation, and through the center of which liquid flows to effect heat exchange. The oxygenating and heat exchange capacity of one plate are studied and compared with similar functions in separate oxygenators and heat exchangers. The data suggest that a multi-plate unit should provide adequate oxygenating capacity and superior heat exchange capacity.