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Biomedical subjects

R S Mittleman

Publications and source records attributed to R S Mittleman.

At least 19 recordsLinked to original sources
PubMed2001

Effectiveness of bi-atrial pacing for reducing atrial fibrillation after coronary artery bypass graft surgery.

Atrial fibrillation (AF) is common after cardiac surgery and adds significant cost and morbidity. The use of prophylactic pacing strategies to prevent post-operative AF has been controversial. We previously performed a pilot study which suggested that the combination of beta-blockers and bi-atrial pacing (BAP) may reduce AF after cardiac surgery. We prospectively randomized 118 patients to continuous BAP for up to 96 hours post-operatively versus standard therapy. All patients were treated with beta-blockers as tolerated. Patients were paced in the AAI mode at a rate of 100 pulses per minute. The primary endpoint of the study was the occurrence of sustained AF (>10 minutes). There was a significant reduction in the incidence of AF in the BAP group among patients undergoing coronary artery bypass graft surgery with or without aortic valve replacement (35 % vs. 19 % AF; OR=0.38, 95 % CI 0.15, 0.93; p <0.05). Including patients undergoing isolated aortic valve surgery (n=7), there remained a strong trend toward a reduction of AF with pacing (no atrial pacing [NAP] vs. BAP; 35 % vs. 21 % AF; OR=0.48, 95 % CI 0.21, 1.11; p=0.08). Patients age 70 or greater benefited most from pacing (NAP vs. BAP; 55 vs. 25 % AF; p<0.05), while those less than 70 years of age did not (17 vs. 18 % p=NS). There was a significant reduction in the amount of time spent in the intensive care unit among patients receiving BAP (50+/-40 vs. 37+/-25 h; p<0.05).BAP together with beta-blockade after coronary artery bypass graft surgery reduces the incidence of post-operative atrial AF. Elderly patients (age 70 or greater) appear to benefit most, and may be a group to whom this therapy should be targeted.

Adult↗
PubMed2000

Case report: anterograde 2:1 and retrograde 3:2 Wenckebach block during atrioventricular nodal tachycardia: controversies of the upper and lower common pathways.

The exact nature of the reentry circuit for the atrioventricular nodal reentrant tachycardia (AVNRT) and particularly the concept and role of the upper and lower common pathways is not well defined. Although it is well accepted that the His-Purkinje system and the ventricles are not an essential part of the tachycardia circuit, controversy still exists as to whether the atria are essential components of the circuit. We describe a patient in whom the AVNRT perpetuated despite the spontaneous development of 2:1 anterograde and 3:2 retrograde block. To our knowledge, such a combination of electrophysiological phenomenon has not been previously reported. The electrophysiological basis of these observations and their clinical implications are discussed.

Cardiac Catheterization↗
PubMed2000

The mode selection trial (MOST) in sinus node dysfunction: design, rationale, and baseline characteristics of the first 1000 patients.

BACKGROUND: More than 200,000 permanent pacemakers will be implanted in the United States in 2000 at a cost of more than $2 billion. Sick sinus syndrome (SSS) will likely account for approximately half of all cases necessitating implantation. Pacemaker technology permits the selection of ventricular (single-chamber) or dual-chamber devices. However, clinical and outcomes data are inadequate to support a clear recommendation that one or the other type of device be used. METHODS: The Mode Selection Trial (MOST) is a single-blind study supported by the National Heart, Lung, and Blood Institute designed to enroll 2000 patients with SSS. All patients will receive a DDDR pacemaker programmed to VVIR or DDDR before implantation. The average time of follow-up will be 3 years. MOST has a >90% power to detect a 25% reduction in the primary end point-nonfatal stroke or total (all cause) mortality-in the DDDR-treated group. Secondary end points will include health-related quality of life and cost effectiveness, atrial fibrillation, and development of pacemaker syndrome. Prespecified subgroups for analysis will include women and the elderly. Enrollment was completed in October 1999, with a total of 2010 patients. RESULTS: The median age of the first 1000 enrolled patients is 74 years, with 25% of patients 80 years or older. Women comprise 49%, and 17% are nonwhite, predominantly black (13%). Before pacemaker implantation, 22% of patients reported a history of congestive heart failure, 11% coronary angioplasty, and 25% coronary bypass surgery. Supraventricular tachycardia including atrial fibrillation was present in 53% of patients. A prior stroke was reported by 12%. Antiarrhythmic therapy was in use in 18% of patients. CONCLUSIONS: MOST will fill the clinical need for carefully designed prospective studies to define the benefits of dual-chamber versus single-chamber ventricular pacing in patients with SSS. The MOST population is typical of the overall pacemaker population in the United States. Thus the final results of MOST should be clinically generalizable.

Aged↗
PubMed1999

Evaluation of right atrial and biatrial temporary pacing for the prevention of atrial fibrillation after coronary artery bypass surgery.

OBJECTIVES: The purpose of this study was to determine if atrial pacing is effective in reducing postoperative atrial fibrillation (AF). BACKGROUND: Atrial fibrillation after coronary artery bypass grafting (CABG) is a common problem for which medical management has been disappointing. Atrial-based pacing has become an attractive nonpharmacologic therapy for the prevention of AF. METHODS: Sixty-one post-CABG patients (mean age = 65 years) were randomized to one of three groups: no atrial pacing (NAP), right atrial pacing (RAP) or biatrial pacing (BAP). Each patient had one set of atrial wires attached to both the right and left atria, respectively, at the conclusion of surgery. Patients in the RAP and BAP groups were continuously paced at a rate of 100 pulses per minute for 96 h or until the onset of sustained AF (>10 min). All patients were monitored with Holter monitors or full disclosure telemetry to identify the onset of AF. The primary end point of the study was the first onset of sustained AF. RESULTS: There was no significant difference in the proportion of patients developing AF in the three groups (NAP = 33%; RAP = 29%; BAP = 37%; p > 0.7). However, for the subset of patients on beta-adrenergic blocking agents after CABG, there was a trend toward less AF in the paced groups. There were no serious complications related to pacing, although in three patients the pacemaker appeared to induce AF by pacing during atrial repolarization. CONCLUSIONS: Continuous right or biatrial pacing in the postoperative setting is safe and well tolerated. We did not find that post-CABG pacing prevented AF in this pilot study; however, the role of combined pacing and beta-blockade merits further study.

Adolescent↗
PubMed1999

Concomitant reentrant tachycardias from concealed accessory atrioventricular bypass tract and atrioventricular nodal reentry in a patient with Williams syndrome.

Williams syndrome is characterized by a constellation of features including mental retardation and supravalvular aortic stenosis. Other cardiovascular abnormalities including arrhythmias contributing to sudden death have been described in these patients. In this report we describe a case of a 49-year-old female with Williams syndrome who presented with severe symptomatic supraventricular tachycardia. Cardiac electrophysiology study identified a left posteroseptal concealed accessory bypass tract responsible for atrioventricular reentrant tachycardia and a concomitant typical atrioventricular nodal tachycardia. Such unusual association of combination of two different types of supraventricular tachycardia and Williams syndrome has not been previously reported. Radiofrequency ablation was successfully performed to cure these arrhythmias.

Atrioventricular Node↗
PubMed1998

Migration and right atrial perforation of an Accufix atrial lead retention wire following partial lead removal during myomectomy.

A 36-year-old man with a history of hypertrophic obstructive cardiomyopathy presented to the emergency room with "stabbing" chest pain. He had undergone dual-chamber pacemaker implantation in 1993 using an atrial lead (Accufix; Telectronics; Englewood, Colo) and a myomectomy in 1996 during which the distal portion of the atrial lead was removed. Digital fluoroscopy revealed that the retention wire had migrated out of the remaining atrial lead and perforated the right atrium. The retention wire was successfully removed percutaneously. The need for complete removal of the retention wire in the Accufix lead at the time of open-heart surgery is emphasized.

Adult↗
PubMed1995

Usefulness of follow-up electrophysiologic study and event monitoring after successful radiofrequency catheter ablation of supraventricular tachycardia. Atakr Multicenter Investigators Group.

We assessed the usefulness of routine follow-up electrophysiologic studies after successful catheter ablation for supraventricular tachycardia and the role of event monitoring as an alternative modality in 310 patients at 11 centers using an investigational catheter ablation system with closed-loop temperature control. A routine follow-up electrophysiologic study between 1 and 3 months after ablation was required as part of the study protocol, and patients developing palpitations after ablation were encouraged to use event monitors. Recurrence of the initially targeted arrhythmia developed in 23 patients (7.4%) at a mean of 1.5 +/- 1.5 months after ablation. However, only 2 of these 23 recurrences were discovered by routine follow-up electrophysiologic study in asymptomatic patients (both with concealed accessory pathways); in the remaining 21 patients a positive follow-up electrophysiologic study was heralded by either recurrent symptoms, documented recurrent supraventricular tachycardia, and/or preexcitation on the electrocardiogram. Eighteen patients complained of palpitations after ablation and received an event monitor, which correctly diagnosed another cause of palpitations and ruled out recurrence of the ablated arrhythmia in 8 patients. Thus, the combination of clinical follow-up and event monitoring appears to be an effective alternative to routine follow-up electrophysiologic studies after catheter ablation of supraventricular tachycardia.

Adolescent↗
PubMed1995

Use of double ventricular extrastimulation to determine the preexcitation index in atrioventricular nodal reentrant tachycardia.

The ability of single paced ventricular beats during tachycardia to penetrate the tachycardia circuit and reset the subsequent atrial depolarization (atrial preexcitation), enabling calculation of the "preexcitation index," can be helpful in analyzing supraventricular tachycardias. However, the ventricular refractory period often prevents ventricular capture of beats with the necessary prematurity to demonstrate atrial preexcitation, particularly in atrioventricular nodal reentrant tachycardia (AVNRT). We hypothesized that the use of double premature stimuli could overcome this limitation. In 25 consecutive patients with either AVNRT or atrioventricular reciprocating tachycardia (AVRT) we attempted to demonstrate atrial preexcitation with single and double ventricular extrastimuli. Whereas atrial preexcitation with a single extrastimulus could only be achieved in 3 of 11 patients with AVNRT, all but 1 patient demonstrated atrial preexcitation with the use of double ventricular extrastimuli. On the other hand, in all but 1 patient with AVRT, atrial preexcitation could be achieved with single and double extrastimuli. A formula was derived for obtaining a preexcitation index with double extrastimuli and shown to correspond closely with the preexcitation index obtained with a single extrastimulus in the 16 patients in whom atrial preexcitation could be achieved with single and double extrastimuli. Thus, this technique significantly enhances the ability to achieve atrial preexcitation and to calculate the preexcitation index in patients with AVNRT, and thus may be useful in deciphering tachycardia mechanism in some patients, as well as being a useful technique in studying the electrophysiological properties of the antegrade and retrograde limbs of AVNRT.

Algorithms↗
PubMed1995

Use of the saline infusion electrode catheter for improved energy delivery and increased lesion size in radiofrequency catheter ablation.

Although radiofrequency catheter ablation has undergone explosive growth as the treatment for a variety of arrhythmias, a limiting factor with the existing catheter delivery system has been the relatively small size of the lesions, which appears to be in part due to coagulum formation around the catheter tip, producing a rise in impedance and limiting energy delivery. In order to test the hypothesis that infusion of saline during radiofrequency current application can increase the lesion size and decrease the incidence of impedance rise, ten dogs were each given two radiofrequency ablation lesions to the left ventricular endocardium. One of these lesions was delivered with a standard 7 French quadripolar catheter with a 2-mm tip, and the second was done with a 7 French luminal electrode catheter (also with a 2-mm tip) for the infusion of normal saline during the delivery of radiofrequency energy. Energy was delivered for 60 seconds at either 10 or 20 watts at two distinct sites in the left ventricle for each animal. Four to 7 days following ablation, the animals were sacrificed for pathological examination. The lesions created with the saline infusion catheter were significantly bigger than those produced with a standard catheter (7.3 x 7.0 x 5.1 vs 5.2 x 4.9 x 3.5 mm, respectively, P < 0.001). At the lower energy level (10 W), none of the animals with the saline infusion catheter experienced an impedance rise versus 3 of 5 of the animals in whom the standard catheter was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Temperature-guided radiofrequency catheter ablation of closed-chest ventricular myocardium with a novel thermistor-tipped catheter.

Successful lesion formation using radiofrequency energy requires adequate tissue heating. Temperature monitoring during ablation may thus improve the efficiency of radiofrequency catheter ablation. Each of five anesthetized, closed-chest adult mongrel dogs weighing 19 to 24 kg received a single pulsed ablation at four left ventricular and two right ventricular sites using a thermistor-tipped 2 mm electrode catheter. The maximum temperature at the electrode-tissue interface was preset at 90 degrees C and current delivered for 40 seconds (method A) or at 70 degrees C for 40 seconds (method B1) or 80 seconds (method B2). With method C, the temperature was set at 90 degrees C for 20 seconds, after which the temperature setting was turned off and ablation continued until impedance increased or the temperature reached > or = 100 degrees C. The size of the resultant lesion was greater with method A than with methods B1, B2 or C (mean length x width x depth, 5.6 x 4.8 x 6.5 vs 4.1 x 4.0 x 5.1 vs 4.2 x 4.0 x 5.2 vs 5.0 x 4.3 x 5.7 mm, respectively; p < 0.01). There was no significant difference in lesion size between pulse durations of 40 seconds (group B1) and 80 seconds (group B2). Only two ablations, both in the anteroapical right ventricle, resulted in a marked rise in impedance without the temperature reaching > or = 100 degrees C. We conclude that temperature (and thus impedance) monitoring improves control and efficacy of lesion formation during radiofrequency catheter ablation.

Analysis of Variance↗
PubMed1994

Coincident idiopathic left ventricular tachycardia and atrioventricular nodal reentrant tachycardia: control by radiofrequency catheter ablation of the slow atrioventricular nodal pathway.

A healthy 37-year-old male presented with a history of frequent palpitations and sustained wide QRS complex tachycardia with a right bundle branch block and left axis morphology. Serial electrophysiological studies revealed two inducible tachycardias, which were shown to represent atrioventricular nodal reentrant tachycardia and idiopathic left ventricular tachycardia. Transformation from one tachycardia to the other occurred spontaneously as well as following atrial or ventricular pacing. Radiofrequency catheter ablation of the slow atrioventricular nodal pathway resulted in cure of atrioventricular nodal reentrant tachycardia and the prevention of spontaneous recurrence of ventricular tachycardia, suggesting a role of atrioventricular nodal reentrant tachycardia in triggering the clinical episodes of ventricular tachycardia. The patient has remained asymptomatic without antiarrhythmic therapy for 8 months.

Adult↗
PubMed1994

Comparison of spectral temporal mapping to the time domain signal-averaged electrocardiogram in normal subjects and in patients with coronary artery disease and sustained ventricular tachycardia.

Spectral temporal mapping is a new form of analysis for signal-averaged electrocardiography, which has the goal of improving the sensitivity and specificity of traditional time domain analysis. Our objective in this study was to determine the effectiveness of one form of spectral temporal mapping, in the face of conflicting results that have so far been reported with this approach. We prospectively performed both spectral temporal mapping and time domain analysis on 50 patients with a history of coronary artery disease and inducible sustained monomorphic ventricular tachycardia (Group 1) and on 25 normal subjects with normal electrocardiograms and no history of heart disease (Group 2). We found that for the 40 Group 1 patients without bundle branch block (Group 1A), the sensitivity of spectral temporal mapping was lower than that for time domain analysis (45% vs 80%, P < 0.005). The results of spectral temporal mapping for Group 1A patients were similar to that for all of Group 1. The sensitivity of spectral temporal mapping was 60% (n = 10) for patients with bundle branch block (Group 1B). The specificity noted in Group 2 was 88% by each means of analysis; however, no one in Group 2 had an abnormal finding by time domain and spectral temporal mapping. Attempts to optimize the criteria for an abnormal spectral analysis did not identify criteria that were superior to those currently in use. We conclude that spectral temporal mapping using Haberl's method is inferior to time domain analysis in identifying patients with sustained ventricular tachycardia, but may be of value in conjunction with the traditional approach in identifying normal subjects.

Action Potentials↗
PubMed1994

Radiofrequency catheter ablation of the atrioventricular junction by a supravalvular noncoronary aortic cusp approach.

Radiofrequency catheter ablation of the atrioventricular junction is usually achieved from either the right or left atrioventricular junction. We describe a new approach in which the atrioventricular junction was successfully ablated from the supravalvular region of the noncoronary cusp of the aortic valve in an unusual patient in whom conventional approaches were unsuccessful.

Atrial Fibrillation↗
PubMed1994

Usefulness of oral quinidine-mexiletine combination therapy for sustained ventricular tachyarrhythmias as assessed by programmed electrical stimulation when quinidine monotherapy has failed.

In patients presenting with sustained ventricular tachyarrhythmias, when oral quinidine monotherapy fails as determined by programmed electrical stimulation, the degree of benefit observed with combination therapy with mexiletine is debated. We prospectively studied 20 consecutive patients (16 men and 4 women) aged 33 to 77 years (mean age, 62 +/- 11 years) who were treated with maximally tolerated quinidine and mexiletine combination therapy and who had ventricular tachyarrhythmias induced at baseline and during oral quinidine monotherapy. Coronary artery disease was present in 19 patients (95%). Programmed electrical stimulation was performed at 2 drive train cycle lengths with up to 3 extrastimuli at two ventricular sites. During follow-up study with combination quinidine-mexiletine therapy ventricular tachyarrhythmias were rendered noninducible in four patients (20%). The remaining 16 patients showed a significant slowing of their tachycardia cycle length (267 +/- 56 msec baseline vs 320 +/- 75 msec with quinidine vs 345 +/- 53 msec with combination therapy, p < 0.05). There was also an increase in the mean QTc interval (452 +/- 50 msec baseline vs 477 +/- 79 msec after quinidine vs 486 +/- 65 msec with combination quinidine-mexiletine therapy, p = not significant) and in the mean ventricular effective refractory period (246 +/- 25 msec baseline vs 281 +/- 37 msec after quinidine vs 290 +/- 25 msec with combination quinidine-mexiletine therapy, p < 0.05). We conclude that sustained ventricular tachyarrhythmias induced during quinidine monotherapy were rendered noninducible by oral combination therapy with quinidine-mexiletine in 20% of cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Usefulness of the response to intravenous procainamide during electrophysiologic study in predicting the response to oral quinidine in patients with inducible sustained monomorphic ventricular tachycardia associated with coronary artery disease.

The response to intravenous procainamide (15 to 20 mg/kg) and to oral quinidine 324 to 648 mg every 8 hours for 3 to 5 days was prospectively studied in 50 consecutive patients (43 men and 7 women, aged 38 to 83 years old [mean 64 +/- 11]) with coronary artery disease and baseline-inducible sustained monomorphic VT. Mean procainamide and trough quinidine serum levels were 10.5 +/- 2.6 and 2.6 +/- 0.8 micrograms/ml, respectively. Mean left ventricular ejection fraction was 37 +/- 12%. Sustained monomorphic VT was suppressed by intravenous procainamide in 18 patients (36%); 8 of these patients (44%) also had suppression with oral quinidine, but 10 (56%) did not. Of the 32 patients (64%) who continued to have inducibility with intravenous procainamide, 12 (38%) responded to oral quinidine and 22 (62%) did not. The overall concordant response rate to intravenous procainamide and oral quinidine was 56% (28 of 50 patients). It is concluded that the response (i.e., the presence or absence of inducible sustained monomorphic VT) to intravenous procainamide does not adequately predict the response to oral quinidine in patients with coronary artery disease and sustained monomorphic VT.

Adrenergic beta-Antagonists↗
PubMed1993

Invasive electrophysiologic evaluation in octogenarians: is age a limiting factor?

To assess the indications, diagnostic yield, and incidence of complications of electrophysiologic testing in the elderly we reviewed our experience with 60 procedures in 45 patients aged > or = 80 years (range 80 to 92 years, mean age 83) undergoing full electrophysiologic evaluation in our laboratory over the past 7 years. The yield of inducible ventricular tachycardia (31%), supraventricular tachycardia (4%), and previously unsuspected conduction abnormalities significant enough to warrant permanent pacemaker implantation (9%), together with the low incidence of complications (1 patient had a deep venous thrombosis and femoral artery pseudoaneurysm, representing an incidence of 2.2% of patients undergoing studies or 3.3% incidence of complications per procedure), suggest that invasive electrophysiologic procedures in the elderly can provide useful information at a complication rate comparable with that of younger patients.

Age Factors↗