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Biomedical subjects

P Troup

Publications and source records attributed to P Troup.

11 recordsLinked to original sources
PubMed1992

Role of implantable cardioverter defibrillator therapy in the management of high-risk patients.

Cardiovascular mortality from ventricular tachycardia (VT) and ventricular fibrillation (VF) continues to be a major health problem. Several therapeutic approaches are now available to treat patients with known VT/VF. Among the various therapeutic options are antiarrhythmic drugs, catheter or surgical ablation of VT focus, and implantable cardioverter defibrillator (ICD). The overall 2-year cardiovascular mortality is significantly reduced by ICD therapy. The ICD is particularly useful in patients with 1) no inducible but clinical VT/VF, 2) drug refractory VT/VF, and 3) VT/VF in association with left ventricular ejection fraction of less than or equal to 30%. Significant improvements in ICD therapy have already been made; these improvements include tiered antitachycardia therapy, antibradycardia pacing, lower defibrillation threshold, and longer life of generator. Further improvements are expected, including nonthoracotomy approach to defibrillation, pectoral implant, and dual chamber sensing. It is likely that with all of the advances in ICD therapy its acceptance as a therapeutic option will increase.

Costs and Cost Analysis↗
PubMed1991

When is it safe not to replace an implantable cardioverter defibrillator generator?

In most reports on patients receiving implantable cardioverter defibrillators, shocks were received mainly during the first 2 to 3 years. Thus, the question had been raised as to the need for device replacement after 3 or 4 years if no shocks had been received. In order to answer this question, shock experience in 184 patients receiving the implantable cardioverter defibrillator was analyzed. Patients were followed for a mean of 24 +/- 18.7 months. A patient's shock was judged to be appropriate if there was electrocardiographic documentation of sustained ventricular tachyarrhythmia at the time of shock or if it was preceded by sudden onset of presyncopal or syncopal symptoms. The majority of patients had coronary artery disease. In approximately two-thirds of patients, left ventricular ejection fraction was below 40%. One hundred fourteen patients had inducible sustained monomorphic ventricular tachycardia. On follow-up, there were 29 deaths, five of which were sudden. Sixty-eight patients received an appropriate shock during follow-up (37%). Over 90% of these 68 received their first shock within the 2 years after implant. The actuarial risk of receiving an appropriate shock by the fifth year after implant was 69%. Conversely, 31% of patients who survived 5 years had not received an appropriate shock. Hazard analysis indicates that there is a high incidence of first appropriate shock during the year following implant. Subsequently, the incidence dropped to a relatively steady rate with a rise in this rate during the fifth year. This analysis suggested a bimodal distribution of appropriate shocks.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1991

Does reception of appropriate shocks from the implantable cardioverter defibrillator affect survival?

The implantable cardioverter defibrillator has become an important therapeutic modality for treatment of life-threatening ventricular tachyarrhythmias. Recent reports have suggested that patients who receive appropriate shocks from this device have an inordinately high overall mortality, and questioned the extent of benefit these patients derive from the implant. This report analyzed the survival among 184 patients who received the implantable cardioverter defibrillator to assess survival differences between patients who received appropriate shocks versus those who did not. At a mean follow-up of 24 +/- 18.7 months, 68 patients received an appropriate shock from their device while 116 did not receive an appropriate shock. Overall survival of the entire population was quite similar to those published by others. There was no significant difference between overall survival of patients who received an appropriate shock versus those who did not. However, there was a statistically significant difference in sudden death mortality. The group of patients that received appropriate shocks included all five sudden deaths. This observation suggested that sudden death in this population was likely due to ventricular tachyarrhythmias rather than strictly bradycardia or asystole. The "benefit" of the device to the entire population was also assessed by estimating survival after receipt of the first appropriate shock. Using this approach, an estimated 10% of patients died without receiving an appropriate shock. In other words, ultimately, 90% of patients were expected to benefit from the device. This survival curve, which initiated only after receipt of the first appropriate shock was fairly similar to those estimated from conventional methods. Therefore, survival after receipt of an appropriate shock was comparable to overall survival and there was no significant difference between survival of patients who received appropriate shocks and those who did not.

Death, Sudden, Cardiac↗
PubMed1991

Coronary artery fistula formation secondary to permanent pacemaker placement.

We present the findings in two patients who apparently developed a coronary artery fistula as a complication of an endocardial pacing electrode. This complication may actually be occurring more frequently than recognized because the patient may be asymptomatic or minimally symptomatic and therefore not undergo a coronary angiogram. Awareness of this potentially serious complication is important and stresses the need for proper electrode placement without excess pressure on the tip.

Cardiac Pacing, Artificial↗
PubMed1990

Automatic implantable cardioverter/defibrillator discharges and acute myocardial injury.

Multiple defibrillations by the automatic implantable cardioverter/defibrillator (AICD) have been reported to result in localized epicardial damage. No data exist, however, regarding whether this damage can be detected in the clinical setting or whether it interferes with the detection of true myocardial infarction. Forty-nine patients who received defibrillations by patch electrodes were studied prospectively. We attempted to document the presence of myocardial injury with the following three commonly used modalities for the detection of myocardial infarction: serial electrocardiographic changes, serial creatine phosphokinase (CPK) and CPK-MB release, and technetium 99m pyrophosphate scanning. Fifteen patients received defibrillations by AICD patches at the time of AICD generator replacement. Nine patients received defibrillations at the time of new AICD lead placement. The average total energy delivered was 85 +/- 29 J. None of these patients had detectable myocardial injury. Ten patients had defibrillations by the AICD patches at the time of bypass operation. One patient in this group developed acute myocardial infarction in the inferior wall after posterior descending coronary bypass operation, as detected by electrocardiogram, 99mTc pyrophosphate scanning, and CPK-MB analysis. Fifteen patients were evaluated for spontaneous AICD discharges. Thirteen had a maximum of five consecutive shocks, and cumulative energy delivered was not greater than 330 J. None of these patients had detectable injury. Two patients had CPK-MB release of 15.3% and 7.5%, respectively. One of these patients had a positive 99mTc pyrophosphate scan. These two patients received 12 and 17 rapid and consecutive AICD discharges, respectively, with cumulative delivered energy of 360 and 510 J, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Strength-duration curves of fixed pulse width variable tilt truncated exponential waveforms for nonthoracotomy internal defibrillation in dogs.

Six anesthetized dogs (wgt 19.6 + 1.1 kg) underwent defibrillation trials using truncated monophasic pulses of 2.5-20 msec in duration. The current pathway consisted of a 4 cm2 RV catheter electrode (cathode) and a 13.9 cm2 subcutaneous chest wall patch (anode). Fibrillation was induced by alternating current and defibrillation attempted 10 seconds later. Only one test shock was assessed for each fibrillation episode. The various durations were tested randomly, and the minimum peak voltage and energy resulting in defibrillation was determined for each. Shorter pulse durations were associated with lower energies with pulses of 2.5-15 msec having significantly lower energy thresholds than shocks of 20 msec (P less than 0.05). The relationship between duration and voltage threshold is hyperbolic with minimum voltage between 7.5 and 12.5 msec while the shortest and longest pulses were associated with the highest voltage thresholds. Shocks of 5 to 15 msec were associated with significantly lower voltage threshold than 2.5 msec pulses (P less than 0.05). The threshold average current (Iav) reached a nadir at 10 msec. Shocks in the midrange of those tested resulted in the best combination of low average current and energy requirements for defibrillation using this nonthoracotomy lead system.

Animals↗
PubMed1988

Simultaneous aortic and mitral valve replacement for lupus endocarditis: report of a case and review of the literature.

Severe aortic and mitral valvular insufficiency developed in a 52-year-old woman with systemic lupus erythematosis after previous treatment with corticosteroids, splenectomy, and cyclophosphamide for immune thrombocytopenia and hemolytic anemia. After aggressive management of the thrombocytopenia, simultaneous prosthetic replacement of both valves was satisfactorily performed; pathologic examination revealed myxoid degeneration. The patient was doing well with excellent valve function 26 months after the operation. The relationship of steroid therapy to lupus valvulitis is reviewed.

Aortic Valve Insufficiency↗
PubMed1986

The automatic implantable cardioverter-defibrillator: evaluating suspected inappropriate shocks.

Two patients who received inappropriate shocks from an implanted defibrillator are presented. In one case, fracture of a sensing lead was responsible and in the other case, sensing of both pacemaker stimuli and the evoked ventricular electrogram resulted in inappropriate shocks. In both cases, phonograms recorded over the generator area with a magnet in place revealed audible tones synchronous with each sensed event which allowed noninvasive documentation of a sensing problem. This procedure appears to be a valuable step both in the confirmation of sensing problems, including pacemaker-defibrillator interactions, and in evaluating suspected inappropriate shocks.

Adult↗
PubMed1984

Amiodarone-induced pulmonary toxicity.

Amiodarone hydrochloride, an investigational drug used to suppress ventricular arrhythmias, may cause pulmonary toxicity with associated radiographic abnormalities. Two patients are presented who illustrate the variability of these abnormalities. One of these patients died of respiratory failure while the other recovered after amiodarone was stopped and corticosteroid therapy was started.

Aged↗
PubMedDate not supplied

Effects of neurodevelopmental treatment on movement patterns of children with cerebral palsy.

Twelve children with mild, moderate, or severe cerebral palsy were examined and videotaped before and after an intensive course of physical therapy in a neurodevelopmental treatment course. These tapes, demonstrating various predetermined movement patterns, were then randomized and viewed by six evaluators. None of the evaluators could tell the difference between before and after films. This demonstrated that significant changes were not seen in children with cerebral palsy after 6 weeks of therapy.

Adolescent↗