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Biomedical subjects

J Kupersmith

Publications and source records attributed to J Kupersmith.

At least 37 records · Page 2Linked to original sources
PubMed1992

Prolongation of isovolumetric relaxation time as assessed by Doppler echocardiography predicts doxorubicin-induced systolic dysfunction in humans.

A reasonably sensitive and specific noninvasive test for doxorubicin cardiotoxicity is needed. In addition, few data exist on the short- and long-term effects of doxorubicin on diastolic filling. To determine if pulsed Doppler indexes of diastolic filling could predict doxorubicin-induced systolic dysfunction, 26 patients (mean age 48 +/- 12 years) were prospectively studied before receiving chemotherapy (control) and 3 weeks after obtaining cumulative doses of doxorubicin. In nine patients developing doxorubicin-induced systolic dysfunction (that is, a decrease in ejection fraction by greater than or equal to 10 ejection fraction units to less than 55%), the isovolumetric relaxation time was prolonged (from 66 +/- 18 to 84 +/- 24 ms, p less than 0.05) after a cumulative doxorubicin dose of 100 to 120 mg/m2. This prolongation preceded a significant decrease in ejection fraction. Other Doppler indexes of filling were impaired after doxorubicin therapy but occurred simultaneously with the decrease in ejection fraction. A greater than 37% increase in isovolumetric relaxation time was 78% (7 of 9) sensitive and 88% (15 of 17) specific for predicting the ultimate development of doxorubicin-induced systolic dysfunction. In 15 patients studied 1 h after the first treatment, doxorubicin enhanced Doppler indexes of filling and shortened isovolumetric relaxation time. In 22 patients, indexes of filling remained impaired and isovolumetric relaxation time was prolonged 3 months after the last doxorubicin dose. In conclusion, doxorubicin-induced systolic dysfunction is reliably predicted by prolongation of Doppler-derived isovolumetric relaxation time. Early after administration, doxorubicin enhances filling and isovolumetric relaxation time. The adverse effects of doxorubicin on both variables persist at least 3 months after cessation of treatment.

Adult↗
PubMed1992

Purkinje fibre-papillary muscle interaction in the genesis of triggered activity in a guinea pig model.

OBJECTIVE: Previous studies have attempted to characterise the genesis of triggered activity related to early afterdepolarisations. Little is known about their conduction behaviour. This study was designed to examine the origin and conduction behaviour of triggered activations to throw light on the pathogenesis of torsade de pointes. METHODS: Electrophysiological interactions related to triggered activations and early afterdepolarisations between papillary muscle and Purkinje fibres were studied in the guinea pig in a single chambered bath. EDTA (5 mM) in Tyrode's solution was used and microelectrodes were placed in both papillary muscle and Purkinje fibres. RESULTS: During early superfusion, marked prolongation of action potential duration and early afterdepolarisations occurred in Purkinje fibres but not in papillary muscle. In addition: (1) with prolongation of action potential duration and early afterdepolarisations in Purkinje fibres, triggered activations arose during phase 2 and were conducted to papillary muscle, where they induced activations; (2) the number of papillary muscle discharges increased with the increase in Purkinje fibre action potential duration in a linear correlation; (3) severing a segment of papillary muscle from Purkinje fibres eliminated these papillary muscle activations; (4) some triggered activations did not conduct to papillary muscle; these had smaller amplitude, slower rate of depolarisation (dV/dt), more positive activation voltage, and similar peak voltages compared to conducted triggered activations; (5) a low plateau resulting from electrotonic interaction was recorded at the Purkinje fibre-papillary muscle junction; this plateau may have facilitated conduction of triggered activations. CONCLUSIONS: In this preparation there was a disparity of effect on Purkinje fibre and papillary muscle. Prolongation of action potential duration and repetitive activations due to early afterdepolarisations originated in Purkinje fibres and were conducted to papillary muscle. Purkinje fibre-papillary muscle interactions are of interest in relation to torsade de pointes arrhythmias which are believed to arise from this mechanism.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1991

Multicenter evaluation of a new fixed-wire coronary angioplasty catheter system: clinical and angiographic characteristics and results.

Coronary angioplasty is increasingly used as an attempt to revascularize patients with severe coronary artery disease. To determine the efficacy of such treatment, a new fixed wire angioplasty catheter was evaluated by a multicenter group in a non-randomized fashion in 50 patients, average 58 +/- 11 years (+/- 1 SD), 58% men. Forty-four percent had a prior revascularization procedure (28% angioplasty, 16% coronary bypass surgery), 38% had a prior Q-wave myocardial infarction, 43% had grade 4 angina, and 60% multiple vessel disease. Angioplasty was attempted in 63 lesions which were located in a mid to distal location in 69%, with a proximal tortuosity score of 1.8 (2 = 45-60 degrees entrance angle), and lesion angulation of 1.4 (1 = 45 degrees lesion bend). In 88%, the device was the primary catheter used and in 6%, it was chosen when another system failed. The balloon was able to successfully cross 94% of all lesions attempted. Six lesions were crossed and dilated but significant residual stenoses remained. There were no significant device malfunctions, or angiographic or clinical complications. This feasibility evaluation of this new fixed wire system yielded excellent angiographic results. Although not a comparative study, this analysis suggests that this new generation of angioplasty catheter may improve the safety and efficacy of complex coronary angioplasty.

Angiography↗
PubMed1991

Two-dimensional transesophageal echocardiographic determination of aortic valve area in adults with aortic stenosis.

To determine if aortic stenosis severity could be accurately measured by two-dimensional transesophageal echocardiography (TEE), 62 adult subjects (mean age 66 +/- 12 years) with aortic stenosis had their aortic valve area (AVA) determined by direct planimetry using TEE, and with the continuity equation using combined transthoracic Doppler and two-dimensional echocardiography (TTE). Eighteen subjects had AVA calculated by the Gorlin method during catheterization. An excellent correlation (r = 0.93, SEE = 0.17 cm2) was found between AVA determined by TEE (mean 1.24 +/- 0.49 cm2; range 0.40 to 2.26 cm2) and TTE (mean 1.23 +/- 0.46 cm2; range 0.40 to 2.23 cm2). The absolute (0.13 +/- 0.12 cm2) and percent (10.8 +/- 8.9%) differences between AVA determined by TEE versus TTE were small. Excellent correlations between AVA by TEE and TTE were also found in subjects with normal systolic function (r = 0.95, SEE = 0.14 cm2; n = 38) and impaired function (r = 0.91, SEE = 0.21 cm2; n = 24). AVA determined by catheterization correlated better with AVA measured by TEE (r = 0.91, SEE = 0.15 cm2) than AVA measured with TTE (r = 0.84, SEE = 0.19 cm2). These data demonstrate that AVA can be accurately measured by direct planimetry using TEE in subjects with aortic stenosis. TEE may become an important adjunct to transthoracic echocardiography in the assessment of aortic stenosis severity.

Adult↗
PubMed1991

Defibrillation efficacy using two low-profile endocardial electrodes.

The hypothesis that improved energy delivery and defibrillation efficacy can be achieved by using two widely separated endocardial electrodes and a cutaneous patch electrode was explored by positioning two 6.5 F electrodes (NuMed, Hopkinton, New York) with 5 cm platinum-iridium coils in the right ventricular apex (RVA) and the right ventricular outflow (RVO) in eight dogs. In another 12 dogs, an additional electrode was positioned in the RVA. A cutaneous patch (P) was placed at the cardiac apex. Biphasic pulses were delivered, the first pulse (6 ms) positive, the second negative (2 ms). The leading edge of the second was equal to the trailing edge of the first. RVO-/P+ and RVA-RVO-/P+ were compared with RVA-/P+ at a constant voltage setting required to achieve a 60% probability of success (P60) for RVA-/P+. At a constant voltage output, the probability of success for RVA-RVO-/P+ was significantly higher (81%) than RVO-/P+ (60%) or RVA-/P+ (67%) (p less than 0.03). The current delivered was greater for RVA-RVO-/P+ (9.9 +/- 2.3 amps) than for either RVA-RVO-/P+ (8.7 +/- 1.9 amps) or RVO-/P+ (9.0 +/- 2.0 amps) (p less than 0.0001). Similarly, the impedance was significantly lower for RVA-RVO-/P+ (66 +/- 12 omega) than for RVA-/P+ (75 +/- 12 omega) and RVO-/P+ (72 +/- 9.6 omega) (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Is defibrillation testing safe?

Determination of defibrillation thresholds (DFTs) and implantable cardioverter defibrillator (ICD) testing requires repeated inductions of ventricular fibrillation (VF) and defibrillation attempts using known energy outputs. Little is known about the individual and cumulative effects of repetitive brief episodes of VF and hypoperfusion on cerebral function. The potential clinical utility of quantitative electroencephalographic (QEEG) monitoring during intraoperative ICD testing, by using processed 19-channel EEG (0.5-35 Hz bandwidth), was examined in ten anesthetized patients, five males and five females (mean age 62 +/- 10 years), who underwent ICD implantation and testing. Ischemic QEEG patterns were defined as those with a 3 standard deviation increase (P less than 0.01) in absolute delta (1.5-3.5 Hz) power persisting for greater than or equal to 2.5 minutes. The majority (80%) of the VF episodes (70) were accompanied by QEEG "slowing" (doubling of the pre-VF low frequency delta waves amplitude). All the patients (5/5) experiencing greater than 6 VF episodes showed a statistically significant increase in the low frequency amplitude. In contrast, this EEG abnormality was apparent in only one of five patients experiencing less than 6 VF episodes. These results suggest a cumulative QEEG depression associated with ICD testing. QEEG may provide an objective means for establishing an individualized upper safe limit of DFT testing and the total number of induced VF episodes.

Electric Countershock↗
PubMed1991

The initial clinical experience with an implantable cardioverter defibrillator/antitachycardia pacemaker.

Guardian antitachycardia pacing (ATP) 4210 is a third generation, multi-programmable cardioverter defibrillator undergoing Phase I clinical trials. The tiered response includes ATP, low energy cardioversion or defibrillation, and bradycardia support. Extensive telemetry is available, including an episode log and details of all episode events. Five patients underwent the implantation of Guardian ATP 4210 as part of a Phase I trial at the University of Louisville. Two of the five patients had multiple VT episodes that were reverted successfully using ATP pacing (slow VT) and defibrillation (fast VT) and VF episodes, which resulted in defibrillation therapy over a follow-up period of 6 to 8 months. Four of the five patients required bradycardia support for bradyarrhythmias unassociated with ATP therapy or defibrillation and one patient required bradycardia support postdefibrillation therapy. The device design is microprocessor based and requires continuous interrogation of the microprocessor memory and checks of the validity of programmed parameters to continue its operation. When the safety check fails, the device is designed to shut down its antitachycardia and defibrillator functions. This design feature has a potential for leaving the patient unprotected if the device shuts down. Modification of this feature is required to ensure the device's long-term safety.

Aged↗
PubMed1991

Effects of stress and beta 1 blockade on the ventricular depolarization gradient of the rate modulating pacemaker.

Prism-CLR is a closed loop, rate modulating pacemaker that uses ventricular depolarization gradient (Gd) to continuously adjust heart rate. Heart rate response to a formal mental stress protocol, esmolol (500 mcg/kg bolus, 75-125 mcg/kg/min infusion), and mental stress during esmolol infusion were studied in six patients to investigate if Gd and paced heart rate response are under direct beta-adrenergic control. Paced heart rates increased in response to mental stress in a physiological manner (P less than 0.001). Response to esmolol infusion was paradoxical, with increased paced heart rates during esmolol bolus and infusion (P less than 0.05). There was no significant alteration in either systolic or diastolic blood pressure during mental stress or esmolol infusion (P greater than 0.05). Paradoxical increase in paced heart rates during esmolol administration suggests a primary or secondary effect of esmolol to decrease the ventricular depolarization gradient. This hypothesis was supported in four dog studies in which direct Gd measurements were made during esmolol infusion. Mental stress during esmolol infusion resulted in significantly increased paced heart rates (esmolol effect) with blunted changes in heart rate in response to the mental stress. The results of this study suggest that the physiological rate response during mental stress is attributable to sympathetic autonomic response.

Adrenergic beta-Antagonists↗
PubMed1990

Preliminary results utilizing a new percutaneous transluminal coronary angioplasty balloon catheter.

We report our initial experience with a new percutaneous transluminal coronary angioplasty (PTCA) balloon catheter and compare it to a similar over-the-wire system in a retrospective, nonrandomized fashion. There was no statistical difference in pre-PTCA angiographic indices and post-PTCA angiographic and clinical success rates between the two groups. There was a trend toward a decrease in length of fluoroscopy (P = .08) and a significant decrease in the amount of contrast utilized (P = .007) with the new balloon catheter. Several new construction features of the new catheter account for this improvement and are discussed. The long-term success of this balloon catheter remains to be investigated.

Adult↗
PubMed1990

Selective effects of tocainide in canine acute myocardial infarction.

We examined the in vivo electrophysiologic effects of tocainide in canine acute myocardial infarction. We compared the effects of tocainide in infarcted and non-infarcted zones. The left anterior descending coronary artery of 8 dogs was ligated and bipolar ventricular electrograms were recorded from a needle electrode placed transmurally in the infarcted zone and from electrodes in the non-infarcted zone. Conduction intervals were measured from the onset of the limb lead QRS to the major deflection of the recorded electrograms in the infarcted and non-infarcted zones. Effective refractory periods were also determined. Measurements were made before, during and after intravenous infusion of tocainide in therapeutic doses 2 hours after infarct. Tocainide prolonged conduction intervals by 26-31% in the infarcted zone at peak (P less than 0.001), but by only 6% in the non-infarcted zone. Similarly, tocainide prolonged the effective refractory period by 27% (P less than 0.001) on the infarcted, but by 8% the non-infarcted zone. Tocainide had very slight effects on QRS duration. The present study shows that tocainide had selective effects in the infarcted zone on both conduction and effective refractory period. These selective effects may explain its antiarrhythmic effects in acute myocardial infarction.

Animals↗
PubMed1990

Low energy partial ablation of the atrioventricular node junction in the dog using a suction-ablation catheter.

A suction electrode catheter was used for low energy, partial ablation of the atrioventricular (AV) node junction in 12 dogs. In 10 dogs, partial injury of the AV node was induced. In six dogs, delivered energy was measured precisely with use of a specially designed electronic circuit. The total energy required for partial ablation was 225 +/- 91 J. The increase in PR (p less than 0.0001) and AH (p less than 0.001) intervals was proportional to the energy delivered. After ablation, the PR interval increased from 98 +/- 10 to 154 +/- 33 ms (p less than 0.004) and the AH interval from 59 +/- 8 to 102 +/- 16 ms (p less than 0.004). There was no significant change in QRS, QTc, HV or RR intervals. AH and PR intervals were significantly prolonged at 3, 7 and 14 days after ablation (p less than 0.05). Anterograde conduction was significantly altered in 10 dogs. Anterograde AV node effective refractory period increased from 157 +/- 14 to 214 +/- 45 ms (p less than 0.005). Anterograde AV node Wenckebach cycle length increased from 196 +/- 30 to 244 +/- 44 ms (p less than 0.002). Retrograde conduction was assessed in three dogs. Retrograde AV node effective refractory period increased from 156 +/- 21 to 260 ms in two dogs, with complete retrograde block in the third. These changes persisted for up to 2 weeks. Pathologic changes were limited to the region of the AV node. In four dogs adherent thrombus without pulmonary emboli was noted. Partial focal injury to the AV node is feasible in the canine model.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Nonpharmacological therapy of supraventricular arrhythmias: surgery and catheter ablation techniques.

Treatment of supraventricular tachyarrhythmias has undergone substantial change and development over the past decade. Pharmacological approaches to management of supraventricular arrhythmias have been supplanted by nonpharmacological techniques. These nonpharmacological techniques are the subject of the present review. The first part of this review will concentrate on the nonpharmacological techniques available for the treatment of supraventricular tachycardia, excluding Wolff-Parkinson-White syndrome, whereas Part 2 will concentrate on the surgical and the ablative procedures for management of tachycardias associated with Wolff-Parkinson-White syndrome. Pacing techniques for termination of supraventricular tachycardias are beyond the scope of this article and will not be included in the discussion.

Animals↗
PubMed1990

Outpatient left heart and coronary arteriography. The current practice at the University of Louisville School of Medicine.

The extension of coronary arteriography into the out-patient population provides more rapid assessment and determination of severity of coronary artery disease in a primary care and referred base population. The speed of the procedure and reduced recovery period are reflected in enhanced cost containment and improved patient compliance and satisfaction. Further technological advancement in this rapidly developing technological field continues to provide improved patient care.

Angiocardiography↗
PubMed1989

Repolarization interactions between cardiac segments of varying action potential duration.

We studied interactions between action potential duration (APD) disperse zones using a double compartment bath in which an APD lengthening solution (Ni++ 2 mmol/L, in Tyrode's solution) was added to one compartment (which contained a portion of the fiber labeled "segment A") followed by addition of an APD shortening solution (6 to 10 mmol/K+) to the other compartment ("segment B"). Standard microelectrode techniques were used in canine Purkinje fibers. With Ni++ in segment A, there was a dispersion in APD measured at both 50% (APD50) and 95% (APD95) of repolarization. After selective addition of K+ to segment B, APD50 dispersion remained constant while APD95 dispersion increased, which indicated a change in the slope of repolarization, a factor with possible arrhythmogenic potential. In addition, a characteristic transitional action potential was seen adjacent to the partition. This had a timely and normally sloping early repolarization followed by a much more gradually sloping shelf. Premature action potentials arising during this shelf had diminished upstrokes. Results of these experiments may be useful in evaluating APD dispersion in relation to arrhythmias.

Action Potentials↗
PubMed1989

Treatment of malignant ventricular arrhythmias with the automatic implantable cardioverter defibrillator.

Twenty-eight patients with malignant ventricular arrhythmias were treated with the automatic implantable cardioverter-defibrillator (AICD) in a 14-month period. Thirteen patients were resuscitated from a ventricular fibrillation (VF) episode. Fifteen patients presented with ventricular tachycardia (VT) refractory to medical therapy. The etiology was coronary artery disease in 23 of 28 patients (82%), dilated cardiomyopathy in 2 of 28 patients (7%), sarcoidosis in 2 of 28 patients, and 1 patient in 28 had lupus erythmatosis. The mean left ventricular ejection fraction was 29%. A total of 27 of 28 patients (96%) patients had inducible ventricular tachycardia using programmed stimulation. The patients considered for AICD implant failed a mean of 3.6 antiarrhythmic drugs. Rate counting and defibrillating leads were inserted through a lateral thoracotomy in 17 patients and a mediansternotomy incision in 11 patients in conjunction with another cardiac procedure in 10 patients. The generators were positioned in a subcutaneous pocket beneath the left costal margin. There were no operative deaths. The mean follow-up was 6.7 months (range 1 to 14) with no VT/VF deaths in patients with defibrillators. The study demonstrated that AICD is an effective device for prevention of sudden cardiac death.

Adult↗