Biomedical subjects
S Furman
Publications and source records attributed to S Furman.
Posterior septal and right free-wall Kent pathways visualized in situ and removed at operation.
This article describes the first posterior septal and first and second right free-wall pathways identified at operation for Wolff-Parkinson-White syndrome and confirmed histologically. All pathways were found in the areas of preexcitation identified by pre and intraoperative mapping. They bridged the atrium and ventricle, and postoperative electrophysiological testing confirmed division of the pathways. Kent bundles may be identified at the time of surgery but they appear to be gossamer structures usually destroyed during surgical manipulation of the coronary sulcus. Visualization of the suspected bypass tract should not alter or limit the extent of surgical dissection.
Antitachycardia pacing and implantable cardioverter defibrillators.
Cardiac pacing can inhibit or terminate a tachyarrhythmia but may also accelerate it to a more malignant rhythm. The automatic implantable cardioverter defibrillator (AICD) terminates ventricular tachycardia and fibrillation and has thus enhanced patient survival. The combination of the two may yet be the most effective means of controlling ventricular tachyarrhythmias and fibrillation.
Pacemaker-mediated endless loop tachycardia at rates below the upper rate limit.
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Automatic methods for detection of tachyarrhythmias by antitachycardia devices.
Electrical devices play an increasingly important role in the control of tachyarrhythmias. Antitachycardia pacing and automatic defibrillation have been severely limited by the poor specificity of tachycardia discrimination in commercially available devices. Although absolute heart rate has been the principal means of automatic diagnosis, several new detection algorithms and methods are being investigated. Multiple electrode timing comparison, signal processing and pattern recognition are employed in these newer techniques. Although each offers some improvement over present technology, none is capable of identifying all arrhythmias. The methods employing comparison of atrial and ventricular rates, without additional criteria, are unable to detect ventricular tachycardia in the presence of 1:1 retrograde conduction. Electrographic analysis techniques require very stable electrodes and may not tolerate normal morphologic variations. A combination of two or more approaches may ultimately be required. All techniques will require that certain critical variables be programmable to allow for individualization in each clinical situation. Soft-ware-controllable devices and those capable of sensing from both the atria and the ventricles will provide the sophistication necessary for the implementation of complex tachycardia detection algorithms. This report reviews automatic tachycardia detection techniques in current use and under investigation.
Frequency spectra of ventricular tachycardia and sinus rhythm in human intracardiac electrograms--application to tachycardia detection for cardiac pacemakers.
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End-of-life behavior.
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Sensors for rate modulated pacing.
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Diagnosis of atrial fibrillation.
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Detection of tachyarrhythmias.
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Performance of implantable cardiac rhythm management devices.
Our data represent use, follow-up, and management decisions from eight independently functioning centers and most importantly, actuarial survival of ICRMD's that have been implanted for a sufficient time period to allow assessment of time versus failure. General patterns of possible target durations for adequate performance for present or future generations of similar clinical devices may be suggested by the data that we have presented. However, it would be inappropriate to conclude from these data that any presently implanted ICRMD would have a particular functional reliability. Furthermore, these data only summarized device hardware performance and cannot and must not be used to determine either short-term or long-term individual patient status, management, or outcome.
Indications for pacemaker implantation.
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Atrial electrogram analysis: antegrade versus retrograde.
Automatic discrimination between antegrade and retrograde atrial electrograms would prevent endless loop tachycardia and contribute to tachycardia detection algorithms. We tested its feasibility by comparing antegrade and retrograde atrial electrograms in 129 patients at the time of atrial lead implantation. Only unipolar, passive-fixation, endocardial, right atrial appendage leads were included. The mean antegrade amplitude was 4.2 +/- 2.2 mV, and retrograde 2.4 +/- 1.5 mV (P less than 0.001); the mean antegrade slew rate was 2.6 +/- 2.1 mV/ms, and retrograde 1.3 +/- 1.1 mV/ms (P less than 0.001). Morphology was similar in 84 patients (65%). The antegrade amplitude exceeded the retrograde by 1.0 mV in 67%, and by 0.5 mV in 81% of patients. Morphology and slew rate contributed little to the discriminating power of amplitude alone. Thus, amplitude criteria reliably distinguish antegrade from retrograde atrial activity.
Differentiation of arrhythmias in the dog by measurement of activation sequence using an atrial and two ventricular electrodes.
Timing of atrioventricular activation and ventricular dispersion identifies and discriminates between beats of different origin. In eight dogs, three bipolar epicardial electrodes recorded left atrial and left and right ventricular depolarizations simultaneously during arrhythmias induced by programmed electrical stimulation and coronary artery occlusion and release. The interval between the left atrial and left ventricular intrinsic deflections (A-V1) and between the left ventricular and right ventricular intrinsic deflections (V1-V2) of each beat was measured. Recordings were of normal sinus rhythm (NSR) (mean of five beats in 8/8 dogs), atrial flutter (AFL) (five beats of one episode), atrial fibrillation (AF) (144 beats in 29 episodes in 7/8), monomorphic ventricular tachycardia (MVT) (24 beats with six morphologies in 2/8), polymorphic ventricular tachycardia (PVT) (63 beats in 15 episodes in 5/8) and premature ventricular contractions (PVC) (29 beats with 29 morphologies in 5/8). Supraventricular rhythms can be differentiated from ventricular rhythms by V1-V2 timing. The mean difference in V1-V2 during AFL and AF vs NSR was 1 ms (range of 0-3 ms). The change from sinus during MVT ranged from 18 to 43 ms (m 31 ms) and during PVC 10 to 75 ms (m 38 ms). Thirty-five of 35 of these ectopic ventricular morphologies exhibited 10 ms or more timing difference compared to corresponding beats of NSR. PVT was consistently distinguished from supraventricular rhythms and MVT by the variability of V1-V2. A-V1 intervals can be used to distinguish supraventricular arrhythmias from sinus rhythm; a 32 ms difference existed for AFL. AF could be detected by the variability in AV1.(ABSTRACT TRUNCATED AT 250 WORDS)
Pacemaker implantation in children: a 21-year experience.
Forty-one children, 20 boys and 21 girls, aged 11 days to 19 years (mean 9.9 years) at initial pacemaker implant, were followed 1 to 248 months (mean 90 months). Ten (mean age 8.2 years) were implanted between 1966 and 1972 (Group I), 14 (mean age 9.9 years) between 1973 and 1980 (Group II) and 17 (mean age 10.9 years) from 1981 through April 1988 (Group III). Arrhythmias were congenital complete heart block in 19, postoperative heart block in 15, acquired heart block in 3, sick sinus syndrome in 3, and bradycardia-induced ventricular fibrillation in 1. Twenty-eight of 41 children had a transvenous implant: 40% of Group I, 71% of Group II and 82% of Group III. Thirteen were cephalic, four subclavian and 11 jugular. Generator site was pectoral in 19, abdominal in 12, intrathoracic in one, and retromammary in nine of 12 girls aged 10 years or more at implant. In Groups I, II and III, 5, 14 and 6 had VOO or VVI units; 5, 0 and 8 dual chamber (VAT, VDD and DDD) pacemakers; 0, 0 and 1 AAI; and 0, 0 and 2 rate-modulated (VVIR) units at initial implant. The average interval between pacer-related hospitalizations in Groups I, II and III was 20, 42, and 39 months. Complications included infection in six, hemothorax in one, and impending pacemaker erosion in one. Six patients died, one of pacer infection, four from primary cardiac disease, and one suddenly without apparent reason. Follow-up continues in 31: 14 are employed full-time, three are homemakers, eight are full-time students, and six are active pre-schoolers.(ABSTRACT TRUNCATED AT 250 WORDS)
Development of a clinical database for the implant and follow-up of cardioverter systems.
The purpose of a clinical database in AICD follow-up is twofold: to follow the evolution (1) of the patient and (2) of the implanted hardware. The pacemaker implant is performed the same day, whereas the implant of a complete AICD system can span over several days or even weeks. Therefore the first design criteria for the database is to clearly identify a single procedure. AICDs require the use of several leads of different types and functions and each lead has to be followed independently. Therefore the second design criteria is to establish a continuous history for each device implanted. To accomplish this the following method has been devised. The implant patient has a single demographic form and for each new procedure a 'Purpose of Procedure' form is filled out, which is identified by the date the form was initiated and by the patient's ID number. There are separate forms for the defibrillator and for three types of leads (transvenous, epicardial sensing and patch leads). For each hardware implanted a specific form is filled out and keyed to the 'Purpose of Procedure' form. Consequently the patient is monitored through the sequence of 'Purpose of Procedure' forms, the defibrillator and the leads through the hardware forms. Stimulation and sensing threshold measurements are part of the respective hardware forms but the induced tachycardia measurements are separate. At present 56 AICDs have been followed in the database.