Biomedical subjects
Publications and source records attributed to S Furman.
An improved method of thoracoscopic implantable cardioverter defibrillators implantation is described. "Mailslot" thoracotomy is more expeditious than thoracoscopic implantation via multiple ports. If required for adequate defibrillation thresholds, subxiphoid, subdiaphragmatic implantation of a defibrillator patch may be performed.
NASPE proposes and supports the concept of a two-tracked training system in cardiac pacing. Track I training will properly train physicians for the prescription of pacemakers and the monitoring of pacemaker patients, and track II training will properly prepare physicians for the implantation of pacemakers. Regardless of specialty (cardiologist or surgeon) or training venue (cardiac pacing fellowship, cardiac electrophysiology and pacing fellowship, sabbatical or mentor sponsored training), it is recommended that these minimum standards be required for hospital credentialing. NASPE also supports the voluntary institution by training program directors of core pacing training in cardiovascular disease and cardiac electrophysiology fellowships. This core training does not in itself constitute proper track I or II training for physicians interested in adequately prescribing, monitoring, or implanting cardiac pacemakers.
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OBJECTIVES: We undertook this study to determine whether telemetered lead impedance measurements (LIM) can be correlated with direct LIM and to determine the stability of LIM over time when measured directly and via telemetry. METHODS: Direct LIM and telemetered LIM were measured in 91 patients; 101 leads during initial implantation and 40 leads during pulse generator replacement. Differences in direct LIM measured during initial implant and pulse generator replacement (direct-direct) were compared in 41 patients (28 atrial leads and 37 ventricular leads). The stability of telemetered LIM obtained immediately postoperatively, at 1 month and 1 year, postimplantation was assessed in 50 patients (23 atrial and 49 ventricular leads). RESULTS: In atrial leads acute direct LIM was 633.9 +/- 18.4 omega versus 575.8 +/- 18.5 omega for telemetered LIM (r = 0.58), and chronic direct LIM was 670.9 +/- 49.3 omega versus 607.0 +/- 36.3 omega for telemetered LIM (r = 0.87). In ventricular leads acute direct LIM was 747.3 +/- 16.9 omega and 684.7 +/- 16.4 omega for telemetered LIM (r = 0.69), and chronic direct LIM was 674.8 +/- 29.9 omega and 625.2 +/- 28.5 omega for telemetered LIM (r = 0.68). The mean direct-direct LIM rose 124 omega (P < 0.001) in atrial leads and 10 omega (P = NS) in ventricular leads. Telemetered LIM for atrial leads was 581.0 +/- 27.6 omega immediately postimplantation compared to 625.7 +/- 34.8 omega at 1 month and 754.1 +/- 43.0 omega at 1 year. Telemetered LIM for ventricular leads was 661.3 +/- 17.5 omega at implant, 684.6 +/- 20.7 omega at 1 month and 724.7 +/- 22.7 omega at 1 year. CONCLUSIONS: There is a good but limited correlation between direct and telemetered LIM. Mean direct LIM obtained at initial implantation is similar to that measured at pulse generator replacement. The telemetered LIM is stable over the first month postimplantation but tends to rise during the first year of follow-up and substantial changes in impedance are not uncommon in individuals with normal function. There is a tendency for LIM to rise with lead maturation. If telemetered LIM is to be followed over time, a baseline telemetered value should be obtained immediately postoperatively.
74 children with acute otitis media (AOM) were entered into an observer-blind randomised multicentre general practice study to compare the efficacy and safety of the new third generation oral cephalosporin, cefetamet pivoxil, at a dose of 10 mg/kg twice daily with the efficacy and safety of cefaclor 10 mg/kg twice daily administered for 10 days. Of 36 evaluable patients in the cefaclor treatment group, 28 (78%) were cured, and a further 4 were improved, giving an overall efficacy rate (cure/improvement) of 89%. Of 36 evaluable patients in the cefetamet pivoxil treatment group, 31 (86%) were cured, and a further 4 were improved, giving an overall efficacy rate of 97%. Adverse events were reported in 4 patients: 1 cefaclor recipient and 3 patients in the cefetamet pivoxil treatment group. Diarrhoea, the most frequently observed adverse event, occurred in both treatment groups. The study results indicate that cefetamet pivoxil and cefaclor appear to have similar efficacy and safety in the treatment of AOM in children.
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To determine the influence of left ventricular (LV) function on survival and mode of death in patients with an implantable cardioverter-defibrillator (ICD), sudden death, surgical mortality, total arrhythmia-related death, total cardiac death and total death were retrospectively evaluated in 377 consecutive patients. The outcomes were also compared between patients with an LV ejection fraction > or = 30% (214 patients, group 1) and < 30% (148 patients, group 2). Surgical mortality was 3.9% (1.8% in group 1, 7% in group 2). During the follow-up of 25 +/- 20 months, actuarial survival rates of all patients at 3 years were 96% for sudden deaths, 81% for total cardiac deaths and 74% for total mortality. When the 2 groups were compared, survival rates of groups 1 and 2 at 3 years, respectively, were 99 and 90% for sudden death (p < 0.05), 97 and 84% for sudden death and surgical mortality (p < 0.01), 94 and 80% for the total arrhythmia-related death (p < 0.001), 88 and 68% for total cardiac death (p < 0.0001), and 81 and 62% for total mortality (p < 0.002). In group 2, 73% of total cardiac deaths within 1 year were causally related to the arrhythmia. Thus, in patients with an ICD, sudden death rates were very low. However, total cardiac death and total death rates were relatively higher. The outcomes of patients with an ICD were strongly influenced by the degree of LV dysfunction.(ABSTRACT TRUNCATED AT 250 WORDS)
Hemodynamic assessment of pacemaker patients is necessary for gauging responses to changes in programming or other conditions affecting circulation. Impedance cardiography permits noninvasive determinations of cardiac output at short intervals but data regarding variability of this method in patients with pacemakers is unavailable. Thirty-eight patients with pacemakers (24 with DDD and 14 with VVI devices) and 6 normal subjects were studied. Each patient was studied in the supine position and repeated impedance measurements were obtained. Fourteen patients were studied during sinus rhythm, 24 were studied during DDD pacing, and 32 patients were studied during VVI pacing. Variability was assessed by methods that analyzed both serial measurements and variability between 2 consecutive and nonconsecutive measurements. The mean indexes and coefficients of variation of 2 and serial measurements in sinus rhythm and DDD were 4%; in VVI it was 6%. The precision of impedance cardiography in all pacing modes, as demonstrated by analysis of variability, indicates that detected changes of stroke volume and cardiac output > 7% on serial (2 and more) measurements, performed by the same operator and during the same session, represent true hemodynamic alterations with 95% confidence. The precision of impedance cardiography demonstrated may be comparable or superior to other frequently used techniques, and the data obtained are valuable both investigationally and clinically.
OBJECTIVES: The purpose of this study was to evaluate the ability of impedance cardiography to determine the change in cardiac output caused by modifications in the atrioventricular (AV) delay in DDD (dual-chamber) pacing mode while pacing the atrium and ventricle at different programmed rates. BACKGROUND: Impedance cardiography permits continuous noninvasive monitoring of hemodynamic variables on a beat to beat basis. METHODS: Eleven patients with a DDD pacemaker were evaluated by impedance cardiography. Stroke volume, cardiac output and total peripheral resistance were assessed in the supine rest position during both DDD and ventricular (VVI) pacing. Hemodynamic variables were measured during DDD pacing at rates ranging from 60 to 110 beats/min in 10-beats/min increments with programmed AV delay varying from 50 to 250 ms in 50-ms increments. When the pacemaker was reprogrammed to the VVI pacing mode, these measurements were repeated at the same pacing rates. RESULTS: Cardiac output measurements during programmed conditions were found to be highly reproducible. The mean coefficient of variation was 3% during DDD pacing; it was 6% in the VVI pacing mode. A large decrease in cardiac output (approximately 30%) was found when a pacemaker was reprogrammed from the DDD to the VVI pacing mode. At DDD pacing rates between 70 to 110 beats/min, the highest cardiac output occurred at an average AV delay of < 120 ms from atrial stimulus to ventricular stimulus. At an average AV delay of > or = 200 ms, the cardiac output in the DDD and VVI pacing modes was similar. CONCLUSIONS: 1) Impedance cardiography allows highly reproducible noninvasive assessments of cardiac output in pacemaker patients; 2) inappropriate programming of the AV interval in patients with atrial and ventricular pacing can decrease cardiac output significantly, and the extent of the decrease is similar to or less than that observed in ventricular pacing; 3) hemodynamic measurements obtained with impedance cardiography can facilitate optimal programming of pacemaker variables.
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Introduction of non-thoracotomy lead systems (Medtronic, Inc.) for the implantable cardioverter defibrillator (ICD) has expanded the indications for use of this mode of therapy. Patients previously considered "too ill" to undergo a thoracotomy as well as patients who are at a high risk for developing sudden death but without previous cardiac arrest, are now considered candidates. The initial experience with the non-thoracotomy lead system at our institution was analyzed for morbidity and mortality. Thirty-four patients underwent attempted intravascular lead implantation, with 30 having initial successful implantation (88.2%). There were 23 males; average ejection fraction (EF) was 38.6%. Three patients developed pulmonary edema and low output immediately after the procedure. Three patients developed electromechanical dissociation during defibrillation threshold testing. A prolonged testing time for the non-thoracotomy lead system was noted when compared to the thoracotomy system (57.39 vs 32.30 min; P < 0.0000). There were more intraoperative morbidities with the non-thoracotomy leads than with the thoracotomy system. There were no perioperative deaths. The potential consequences of prolonged anesthesia time and extensive defibrillation threshold testing should be considered when choosing the route of ICD implant, the type of anesthesia, and the intraoperative testing protocol for each patient.
UNLABELLED: Implantable cardioverter defibrillators (ICD) currently undergoing clinical investigation incorporate antitachycardia pacing capabilities, but little is known about their effect on patient selection and outcome. The Bilitch registry database was reviewed to compare the 1,553 patients who initially received standard devices with the 242 patients initially implanted with antitachycardia pacing ICDs (ANT). Baseline characteristics including mean age, ejection fraction, sex, type of cardiac disease, and percent presenting with sudden cardiac death were reviewed. Cumulative first shock occurrence and survival from arrhythmic and all cause mortality were calculated for the two groups. RESULTS: Patient characteristics were similar in the two groups except that the ANT population had a greater male predominance and initially presented with a lower sudden cardiac death incidence (P < 0.05). Cumulative occurrence of first shock was significantly lower in the ANT group up to 24 months of follow-up (28% vs 36%, P < 0.05). ANT group survival from arrhythmic death (99% vs 96%) and all cause mortality (89% vs 94%) was significantly higher at 24 months of follow-up (P < 0.05). CONCLUSIONS: The addition of antitachycardia pacing to ICD therapy appears to significantly limit the occurrence of first ICD shock without adversely affecting mortality in a patient population similar to those implanted with standard ICDs.
The Bilitch ICD Registry includes 1,869 patients from 13 medical centers enrolled between March 1982 and April 1992. Of these, 95 patients had their units removed and not immediately replaced (77 males/18 females mean age 54.9 +/- 13.0 years, range 10-76). The mean duration of implanted ICD was 19.5 +/- 18.2 months, mean ejection fraction 30.1 +/- 11.7%. Coronary artery disease was present in 55 patients, absent in 30, and unknown in 10. The presenting clinical event was sudden death in 35 patients, symptomatic ventricular tachycardia in 34, other causes in 6, and unknown in 20. Reasons for ICD removal were: infection in 33 patients, cardiac transplant in 32, elective in 20, following battery depletion in 7, lead system failure in 2, and inappropriate shock in 1. Of all groups who had their ICD removed, the patients who had removal for cardiac transplantation had the highest incidence of appropriate ICD discharges while the device was implanted (43.8%). Of the 63 nontransplanted patients seven were lost to follow-up while alive. Of the 56 remaining, 17 died (1 cause unknown, 6 noncardiac, 3 sudden, 1 arrhythmic, 6 nonsudden nonarrhythmic cardiac death), 7 had an ICD reimplanted, and 32 are alive and well without an ICD. Follow-up for the 32 cardiac transplant patients: 2 were lost to follow-up while alive, 2 died of nonsudden nonarrhythmic death, and 28 are alive and well. The survival of patients who had their ICD removed and not reimplanted was not different from that of patients who never had their ICD removed up to 2 years.(ABSTRACT TRUNCATED AT 250 WORDS)
From March 1982 to May 1, 1992, 105 consecutive patients underwent initial implant of cardioverter defibrillators (ICD) at our institution. Twenty-nine patients (23 male and 6 female, average ejection fraction 32.24%) with ICD systems implanted via thoracotomy and either intra- or extrapericardial patches, had one or more revisions including 56 generator changes or staged implant procedures, three patch revisions, one patch lead fracture without revision, and one sensing lead revision. The time between pulse generator revisions averaged 19.5 months. Initial defibrillation threshold mean was 12.8 joules (n = 25); at first revision, 14.46 joules (n = 29), (P = NS); by fifth revision, 15.0 joules (n = 2), (P = NS). One patch was noted to be crinkled at 70 months; one patch had migrated by 39 months, and two patch leads had fractured at the costal margin by 69 and 90 months. One patient with marginal defibrillation thresholds had an additional patch placed at revision to an upgraded ICD unit. Once acceptable defibrillation threshold (DFT) is obtained, the long-term intrapericardial DFT remains stable unless a specific problem occurs. As a small, nonstatistically significant increase in DFT may occur, caution must be exercised in patients with marginal DFTs.