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Biomedical subjects

T J Cohen

Publications and source records attributed to T J Cohen.

At least 19 recordsLinked to original sources
PubMed2001

Initial clinical experience with implantable loop recorders.

The purpose of this study was to review the initial experience of a university hospital with Implantable Loop Recorders (ILR) for diagnosis of recurrent unexplained syncope or presyncope. Twelve patients with syncope or presyncope of unknown etiology (who had a negative tilt table test, electrophysiologic study, and neurologic work-up) underwent implantation of ILR. All implants were performed using the Reveal ILR (Medtronic AVE, Santa Rosa, California). The 8 cc device is 61 mm long, 19 mm wide, 8 mm thick and weighs 17 grams. It has 18 months of battery life and has 2 electrodes with 38.5 mm spacing. The device is nonvascular and is implanted approximately 2 fingerbreadths below the clavicle in a subcutaneous pocket (1.5 inches long) and is secured via polydacron suture to the pre-pectoral fascia/pectoralis muscle. Twelve patients with a mean age of 61 +/- 22 years received the ILR. Ten patients had syncope and 2 had presyncope. Three patients had coronary artery disease and 2 had dilated cardiomyopathy. ILRs were implanted for a mean follow-up period of 7.2 +/- 5.8 months (range, 1 day to 18 months). Two patients still continue to be monitored at the time of this report. The mean number of events prior to ILR was 6.0 +/- 5.4. Eight patients (66%) had recurrent syncope after implantation. One patient was not available for follow-up. There were no significant complications from the implant. In 5/12 patients (42%), the ILR helped to diagnose the etiology of the syncopal episode. Syncope was secondary to asystole in three patients, junctional bradycardia in another patient, and seizure activity in a fifth patient (high-frequency noise recorded on the electrocardiogram during sinus rhythm). The 4 patients with ILR-documented bradyarrhythmias underwent permanent pacemaker implantation and are alive and well. ILR implantation is a simple, useful and safe method in assisting with the diagnosis of recurrent unexplained syncope or presyncope after an inconclusive electrophysiologic and neurologic evaluation.

Adult↗
PubMed2000

An association between anxiety and neurocardiogenic syncope during head-up tilt table testing.

To study the association between anxiety and neurocardiogenic syncope as determined by head-up tilt table testing (HUT) in men and women with presyncope or syncope, patients with unexplained syncope or presyncope undergoing HUT were asked to complete the Burns Anxiety Inventory (BAI), a validated inventory of 33 questions with responses graded from 0 to 3. HUT consisted of a 30-minute tilt to 60 degrees, which if negative, was repeated with an isoproterenol infusion. A positive HUT was defined as symptomatic hypotension and/or bradycardia. Of the 66 patients who completed the BAI and underwent HUT, 33 were men and 33 were women. The mean age was 57 +/- 18 years (17-91 years). Patients with a positive HUT had a higher BAI score than those with a negative HUT (22 +/- 12 vs 14 +/- 13, P = 0.017). This association was stronger in women with a BAI score of 24 +/- 11 in those with a positive HUT versus 13 +/- 8 in those with a negative HUT (P = 0.005). In contrast, the mean BAI score for men with a positive HUT was 19 +/- 13, as compared to 15 +/- 16 for a negative HUT (P = 0.5). In conclusion, the present study demonstrates a statistical association between anxiety (as determined by BAI) and HUT result. Gender-based analysis revealed a more statistically significant relationship between anxiety and HUT outcome for women as compared to men.

Adult↗
PubMed2000

Elevation of defibrillation thresholds with propofol during implantable cardioverter-defibrillator testing.

A 26-year-old man with severe dilated cardiomyopathy and frequent ventricular tachycardia treated with propafenone plus mexiletine underwent implantable cardioverter-defibrillator testing one day after dual chamber defibrillator implantation. There were no significant changes in the R-wave and lead position on chest x-ray. Routine defibrillator threshold (DFT) testing after 320 mg intravenous propofol demonstrated high DFTs (greater than 31 Joules and requiring 360 Joules externally for termination). Change in polarity failed to improve DFTs. After about 20 minutes of washout, conscious sedation was performed with 20 mg of midazolam and repeat DFTs were equal to 21 Joules. This case demonstrates the potential for an acute dose dependent rise in DFT with propofol.

Adult↗
PubMed2000

Revealing data retrieved from an implantable loop recorder.

This patient is an 80-year-old man with a history of recurrent syncope of unknown etiology who underwent an extensive cardiac and neurologic evaluation which was essentially negative. The patient subsequently received an implantable loop recorder (Reveal , Medtronic, Inc., Minneapolis, Minnesota). Eight months after implantation, this device was activated by the patient following a syncopal episode. The episode revealed over 30 seconds of sinus arrest with only 3 ventricular escape complexes observed during that time. The patient activated this device and was subsequently referred for a dual chamber permanent pacemaker, which was implanted without complications. This case illustrates the advantages of a non-vascular, implantable loop recorder for helping to define the etiology of recurrent unexplained syncope.

Aged↗
PubMed2000

Successful radiofrequency catheter ablation of a right posterolateral bypass tract in a patient with Wolff-Parkinson-White syndrome after a previous failed ablative procedure: taking the high road.

A 16-year-old high school basketball player with symptomatic Wolff-Parkinson-White syndrome underwent an unsuccessful radiofrequency catheter ablative procedure from the femoral venous approach. During this procedure, the patient received 30 applications of radiofrequency energy without injury to the accessory pathway. The patient was treated with flecinide 100 mg orally twice daily and rescheduled for a second ablative procedure via the right internal jugular venous approach. At the second session, prior to any right internal jugular venous applications, 3 additional applications were delivered via the right femoral venous approach using a different catheter, without success. A single radiofrequency energy application from the right internal jugular venous approach eliminated the bypass tract in approximately 2 seconds. The superior approach achieved a more stable catheter position thereby eliminating the bypass tract. In conclusion, an alternative plan of attack should be considered after multiple failures from a given approach. In other words, take the high road if you can't take the low road.

Adolescent↗
PubMed1999

The utility of quantitative body surface isoarea mapping for predicting ventricular tachyarrhythmias.

Noninvasive techniques, such as the signal averaged ECG, have been used to assess risk of ventricular tachyarrhythmias (VT). However, these methods produce false positive and negative results. The purpose of this study was to develop body surface map algorithms which would enhance prediction of susceptibility to VT. Fifty-three patients referred for programmed electrical stimulation were enrolled in this study. All patients underwent signal averaged ECG, body surface map, programmed electrical stimulation. Group I patients had no sustained inducible VT and group II patients had either inducible sustained VT at electrophysiology study or previously documented spontaneous, sustained VT. For body surface map analysis, the difference between extrema on isoarea maps was calculated and defined as the gradient range. An abnormal body surface map was defined as a QRST gradient range < or = 109 mv.ms. The mean QRST gradient range in group II was significantly < that in group I (P < 0.05). By logistic regression analysis, the presence of coronary artery disease, a QRST gradient range < or = 109 mv.ms, an EF < 40% and a signal averaged ECG QRS duration > 114 ms predicted VT. The sensitivity, specificity, positive and negative predictive values for predicting VT susceptibility of an algorithm which combines the signal averaged ECG QRS duration and the QRST gradients were 0.93, 0.76, 0.79, and 0.91, respectively, while those for the signal averaged ECG alone were 0.52, 0.69, 0.63, and 0.59 for VT susceptibility. A combined body surface map-signal averaged ECG algorithm was more sensitive in detecting susceptibility to VT than the signal averaged ECG alone.

Adolescent↗
PubMed1999

Utility of intracardiac echocardiography (ICE) in electrophysiology: ICEing the CAKE (catheter ablation knowledge enhancement).

PURPOSE: Previous studies have demonstrated the utility of intracardiac echocardiography (ICE) during electrophysiologic procedures including radiofrequency catheter ablation. The purpose of this study was to analyze the initial learning experience with ICE during invasive electrophysiologic procedures. METHODS: During a 1-month ICE trial, patients scheduled for radiofrequency catheter ablation underwent concurrent imaging using a 9 French, 9 MHz catheter in the right atrium proximal to important endocardial structures and diagnostic/ablation catheters. The procedure length, fluoroscopy and ICE times were systematically recorded during each procedure. In addition, the images were analyzed and recorded and their utility was evaluated after each case. A case control analysis was also performed. RESULTS: Seven patients underwent ICE (as part of an ICE trial period) during their electrophysiology study between July 21 and August 13, 1998. This study demonstrated the utility of ICE in identifying radiofrequency catheter tip stability and intracardiac and endocardial structures, including the crista terminalis, coronary sinus, and foramen ovale. CONCLUSION: ICE contributes to the electrophysiology arsenal for both diagnostic and therapeutic procedures. In particular, this technique demonstrated a decrease in fluoroscopy time as compared to a case control population. This technique limits radiation to the patient and operator. In addition, endocardial structures, which may be pivotal in diagnosing and treating cardiac arrhythmias, were easily identified. Radiofrequency catheter stability can also be assessed with this technique.

Adult↗
PubMed1999

The effects of intrinsic sympathomimetic activity on beta-blocker efficacy for treatment of neurocardiogenic syncope.

To compare the efficacy and side effects of beta-blockers with intrinsic sympathomimetic activity (ISA) to those without ISA, we retrospectively reviewed patients diagnosed with neurocardiogenic syncope (NCS) as determined by head-up tilt table testing. Four hundred and thirty-one patients (mean age of 57 +/- 25 years) underwent head-up tilt table testing for syncope of unknown etiology, of which 120 patients were diagnosed with NCS; 87 of these patients were treated with beta-blocker therapy. Only 56 patients could be contacted during follow-up. Twenty-eight patients were treated with beta-blockers with ISA (acebutolol or pindolol) and 28 received beta-blockers without ISA (atenolol or metoprolol) based on physician preference and followed for up to 2 years. During the follow-up period, beta-blockers with or without ISA had comparable clinical efficacy in suppressing recurrent syncope in patients with NCS. However, beta-blockers with ISA were better tolerated and caused less fatigue (32% side effects) as compared to those without ISA (50% side effects; p = 0.23). The benefits of beta-blockers with ISA were more pronounced in patients less than 60 years old (19% side effects with beta-blocker with ISA as compared to 85% side effects with beta-blocker without ISA; p = 0.0004). Beta-blockers without ISA appear to be better tolerated and caused less fatigue in patients 65 years old or greater (20%) than in patients less than 65 years old (85%; p = 0.0002).

Acebutolol↗
PubMed1998

The effects of pneumothorax on defibrillation thresholds during pectoral implantation of an active can implantable cardioverter defibrillator.

Pneumothorax has previously been reported to increase defibrillation thresholds and lead impedance in monophasic systems. This article demonstrates a case using an active can system in which the lead impedance between the right ventricular defibrillation coil and the device improved from 70 omega with pneumothorax to 48 omega after resolution. The defibrillation threshold also improved from > 30 J to < or = 10 J after the pneumothorax had resolved. We conclude that acute pneumothorax can increase the transthoracic lead impedance and defibrillation thresholds; however, with resolution both parameters can return to acceptable levels with an active can system.

Aged↗
PubMed1997

A simple electrocardiographic algorithm for detecting ventricular tachycardia.

The purpose of this study was to determine whether a simple ECG algorithm could be developed for predicting susceptibility to ventricular tachyarrhythmias (VT) as defined by sustained spontaneous or inducible VT. Two different QT dispersion algorithms were determined by the difference between the longest and shortest QT interval measured in three orthogonal leads (I, aVF, V1; QTD3), and at least 11 of 12 leads (QTD12) from the 12-lead ECG. These QT dispersion algorithms were investigated (with and without the QRS duration from the 12-lead ECG) and compared to the signal-averaged ECG (SAECG) in order to determine their sensitivity and specificity for detecting VT. Only patients who underwent SAECG and were referred for programmed electrical stimulation were included in this study. A positive SAECG was defined by filtered QRS duration > 114 ms, and/or low amplitude signal duration > 38 ms, and/or root mean square voltage in the last 40 ms of < 20 microV. Sixty patients were enrolled in this study with a mean age of 63 +/- 2 years. Fifty-five percent of the patients had coronary artery disease. A simple ECG algorithm consisting of the sum of QTD3 plus the QRS duration had a sensitivity and specificity of 90% and 63%, respectively, wheras the SAECG had a sensitivity and specificity of 60% and 63%, respectively (P = 0.022). We conclude that a simple ECG algorithm is more sensitive than the SAECG for predicting VT. This algorithm combines two easily measured variables obtained from the 12-lead ECG, and can easily be performed without expensive computer equipment.

Adolescent↗