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D Pantopoulos

Publications and source records attributed to D Pantopoulos.

12 recordsLinked to original sources
PubMed1988

Sequential transvenous pacing and shock therapy for termination of sustained ventricular tachycardia.

Rapid ventricular pacing and transvenous shocks are both effective in terminating sustained ventricular tachycardia (VT) only in selected patients. We prospectively examined efficacy and safety of an algorithm for VT termination combining rapid ventricular pacing with low and moderate energy transvenous shocks in patients with sustained VT. Sixty-three VT episodes in 23 patients, mean age 64 +/- 12 years, were treated with the algorithm. Bursts of rapid ventricular pacing and transvenous shocks were delivered with a Medtronic 6880 catheter positioned in the right ventricular apex. VT episodes with cycle lengths greater than 270 msec (group A) were treated with sequential therapy with rapid ventricular pacing (90%, 80%, and 70% of VT cycle length), low energy transvenous shocks (0.5 to 2.7 J), and moderate energy (2.7 to 10 J) transvenous shocks. Rapid VT episodes with cycle lengths less than 270 msec (group B) were treated with moderate energy transvenous shocks directly. Forty-one of 48 (85%) VT episodes in group A and 6 of 15 (40%) VT episodes in group B were successfully terminated by this algorithm. There was no difference in clinical or arrhythmia characteristics between responders and nonresponders in either group A or group B to the algorithm. VT acceleration was observed in 12% of episodes in group A and in 47% of episodes in group B. We conclude that an algorithm combining rapid ventricular pacing with low and moderate energy transvenous shocks is effective for VT termination in episodes with a cycle length greater than 270 msec and can reduce the need for transthoracic cardioversion.(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1987

Intraoperative mapping-guided argon laser ablation of malignant ventricular tachycardia.

Intraoperative mapping-guided laser ablation of arrhythmogenic myocardium was performed in 5 patients with refractory sustained ventricular tachycardia (VT). Using a 15-W argon laser coupled to a 300-mu optical fiber, a bloodless laser ventriculotomy was successfully performed in 4 patients with VT. Visually- and mapping-guided endocardial ablation of 7 VT morphologic patterns was performed. Five of the 7 sites of VT origin were unresectable using standard resection techniques. Postoperatively, spontaneous and inducible VT was suppressed in all patients (without antiarrhythmic drugs in 4 patients and with a previously ineffective drug 1 patient). Mean pulmonary capillary wedge pressure, cardiac index and left ventricular ejection fraction were unchanged (p greater than 0.2) from preoperative values. Mean maximal creatinine kinase-MB isoenzyme concentration was 139 +/- 75 IU. All patients were New York Heart Association functional class II at discharge. During follow-up, no spontaneous arrhythmia has recurred in any patient. Thus, intraoperative argon laser ablation is effective for VT ablation alone or in conjunction with standard surgical resection techniques.

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PubMed1987

Mechanisms of ventricular tachycardia termination and acceleration during transvenous cardioversion as determined by cardiac mapping in man.

We examined the EP mechanisms underlying efficacy and inefficacy of transvenous cardioversion shocks in 13 patients with coronary artery disease and sustained VT during preoperative and intraoperative cardiac mapping procedures. Shocks were delivered at the right ventricular apex with a Medtronic 6880 catheter and a Model 5350 external cardioverter/defibrillator with two or three electrode configurations, resulting in unidirectional or bidirectional shocks, respectively. Single transvenous shocks with incremental energies ranging from 0.03 to 25 J were delivered in sinus rhythm and VT, and simultaneous right and left ventricular electrograms were obtained. Transvenous cardioversion shocks of 0.03 J in sinus rhythm and VT produced immediate local right ventricular depolarization and subsequently conducted to distant right ventricular and left ventricular sites after 30 to 100 msec. Shocks of 0.05 to 0.5 J produced immediate depolarization of progressively larger right ventricular and left ventricular regions, with shocks greater than or equal to 0.5 J producing immediate depolarization of distant left ventricular sites in sinus rhythm. High energy (greater than 5 J) shocks produced instantaneous depolarization of multiple right ventricular and left ventricular sites in VT. VT termination occurred due to either delay or interruption of conduction in the tachycardia circuit, despite prior depolarization of the early sites of ventricular activation during the QRS complex. This could be due to instantaneous or paced depolarization of critical "excitable" components of the VT circuit, resulting either in immediate conduction block or in instability followed by termination. VT acceleration with transvenous cardioversion was due to modification of the "excitable," slowly conducting components of the VT circuit with the development of new areas of conduction block, along with altered intraventricular conduction. Similar EP mechanisms were observed with unidirectional and bidirectional transvenous shock patterns. We conclude that transvenous shocks alter conduction in human ventricle, and clinical effects of QRS synchronized shocks are related to conduction changes induced in the excitable components of the VT circuit.

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PubMed1987

A prospective evaluation of single and dual current pathways for transvenous cardioversion in rapid ventricular tachycardia.

By using a prospective randomized study design, we compared the clinical efficacy and safety of single unidirectional and bidirectional transvenous cardioversion shocks for termination of rapid ventricular tachycardia (VT) having cycle lengths less than 300 ms. A Medtronic 6880 catheter was placed in the right ventricular apex and an R2 skin patch electrode was placed over the left scapula. Patients were randomized into two groups. Group A patients received unidirectional transvenous shocks using the two catheter electrodes (right ventricular apical cathode and superior vena caval anode) which resulted in a single current pathway. Group B patients received bidirectional transvenous shocks using a common cathode (right ventricular apex) and two separate anodes (superior vena caval and R2 patch) resulting in two current pathways. Identical shocks with total energies of 2.7, 5.0 and 10.0 J and waveform tilt of 27% were delivered to Groups A and B. In selected Group B patients, delivered shock currents through the right ventricular apex/superior vena caval and right ventricular apex/R2 patch electrode pairs were measured. We analyzed the initial episode of VT with a cycle length less than 300 ms in 33 patients with organic heart disease (mean age, 64 +/- 9 years; mean VT cycle length, 248 +/- 37 ms) who underwent programmed electrical stimulation. Transvenous cardioversion shocks terminated 31% of 16 VT episodes in Group A and 41% of 17 VT episodes in Group B (p greater than .2). The mean successful shock energy was 6.1 +/- 3.7 J in Group A and 3.0 +/- 0.9 J in Group B (p less than .05). Forty percent of all successfully cardioverted episodes in Group A and 86% of all successfully cardioverted VT episodes in Group B were terminated at an energy of 2.7 J (p = .09). Analysis of shock waveforms in Group B revealed 47 to 74% of the total current was transmitted through the right ventricular apex/superior vena caval electrodes and 26 to 53% through the right ventricular apex/R2 electrodes. We conclude that single bidirectional transvenous shocks are effective for rapid VT termination in selected patients. Dual current pathways decrease energies needed for successful transvenous cardioversion in this patient population.

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PubMed1987

Prospective evaluation of a sequential pacing and high-energy bidirectional shock algorithm for transvenous cardioversion in patients with ventricular tachycardia.

Rapid ventricular pacing alone or in combination with low- or intermediate-energy shocks has limited efficacy in cardioverting rapid ventricular tachycardia (VT) when delivered through two transvenous catheter electrodes. This prospective study determined the efficacy and safety of an algorithm that used a sequence of rapid ventricular pacing (RVP) and intermediate-energy (5 and 15 J) and high-energy (25J) single, bidirectional shocks delivered by two transvenous catheter electrodes in conjunction with a cutaneous electrode in patients with sustained VT. The bidirectional shock was simultaneously delivered over two electrical vectors via a common right ventricular apical cathode and tow anodes consisting of the superior vena caval catheter electrode and cutaneous patch. The electrical therapy delivered was determined by the cycle length of VT. Slow VT (cycle length greater than 300 msec) was sequentially treated by RVP followed by incremental bidirectional shocks of 5, 15, and 25 J. Rapid VT (cycle length less than 300 msec) was treated with no incremental bidirectional shocks of 15 and 25 J. VT was reinduced to determine reproducibility of the algorithm for episodes that were successfully terminated. For patients in whom the primary algorithm failed, a second algorithm was used that excluded 5 and 15 J shocks and went directly to a 25 J shock. VT was reinduced twice and the secondary algorithm was evaluated. Thus, reproducibility of termination of VT with the primary and secondary algorithm was examined. Fifty episodes of slow VT and 40 episodes of rapid VT were induced in 22 patients (mean left ventricular ejection fraction 31 +/- 14%). Six patients had rapid VT, nine patients had slow VT, and seven patients had both.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Usefulness of an implantable antitachycardia pacemaker system for supraventricular or ventricular tachycardia.

The Cordis Omni-Orthocor model 234A, an implantable antitachycardia system, was evaluated in 13 patients. Two patients had recurrent sustained supraventricular tachycardia (SVT) and 11 had ventricular tachycardia (VT). The system was used for SVT or VT termination (group 1: SVT, 2 patients; VT, 4 patients) or for demand pacing and noninvasive electrophysiologic studies for tachycardia induction and serial electrophysiologic testing alone (group 2: VT, 7 patients). The overdriver was used successfully in 4 of 6 patients in group 1 for repeated tachycardia termination (SVT and VT) during a mean follow-up period of 18 months. One patient had 1 sustained VT episode unresponsive to pacing and 1 patient had no recurrence of tachycardia. Tachycardia termination zones varied when using the system in 2 patients receiving long-term amiodarone therapy. Eighteen noninvasive electrophysiologic studies for serial drug testing were performed, 4 in group 1 and 14 in group 2. Clinical tachycardia was induced and successfully terminated by use of the overdriver in 12 studies. It is concluded that implantable antitachycardia systems can be used successfully for noninvasive tachycardia induction and termination and for reliable serial electrophysiologic studies. Such systems provide improved patient safety and acceptability and are reasonable in cost.

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PubMed1986

Laser ablation of normal and diseased human ventricle.

The feasibility and safety of laser photoablation in patients with ventricular tachycardia (VT) and accessory pathways are currently being examined. We studied the qualitative and quantitative effects of argon laser radiation on normal and diseased human ventricle to determine the relationship between the size of tissue lesion and delivered energy. Twenty-nine human ventricle segments (normal ventricle = 10; diseased ventricle = 19) were excised from patients during mapping-guided subendocardial resection for VT (seven patients), mitral valve replacement (five patients), or immediately at autopsy (three patients). Lasing was performed with a 15 W argon laser coupled to a 300 micron optical fiber. Incremental laser discharges from 10 to 1000 J were delivered in air and saline with the optical fiber 5 mm from the endocardial surface. Gross and microscopic damage was quantified and correlated with laser discharges at low (10 to 100 J), intermediate (101 to 300 J), and high (greater than 300 J) energies. Histologic examination of laser-induced lesions in both normal and diseased human ventricle in either medium showed focal thermal injury with crater formation, vacuolization, and coagulation necrosis of endocardium and myocardium. In normal ventricle, mean lesion diameter and depth in air increased with increasing energies up to 300 J. Over 300 J, tissue perforation was frequently observed. In saline, the mean lesion depth was significantly reduced (p less than 0.02) at comparable energies. In diseased ventricle, mean lesion diameter and depth in air and saline also increased with increasing laser discharge energies up to 300 J. Higher energy laser discharges did not increase mean lesion dimensions or result in tissue perforation.(ABSTRACT TRUNCATED AT 250 WORDS)

Endocardium↗
PubMed1986

Comparative efficacy of continuous and pulsed argon laser ablation of human diseased ventricle.

We compared the tissue lesions obtained in a saline medium using single continuous argon laser discharges with paired sequential continuous laser discharges in nine segments of diseased human ventricle resected from patients with and without ventricular tachycardia (VT) at cardiac surgery. Single continuous argon laser discharges were delivered to separate sites on the endocardial surface of the tissue segments for periods of 10, 20, and 30 seconds at laser beam power of 5 W (group IA) and 8 W (group IIA). Paired sequential argon laser discharges of 5, 10, and 15 seconds in duration were delivered to separate sites at a laser power of 5 W (group IB) and 8 W (group IIB). Gross and microscopic examination of each tissue lesion and its dimensions were performed. Laser irradiation of excised human ventricle resulted in a circular discrete burn at the site of application. Histologic examination showed crater formation due to tissue vaporization with the crater lining consisting of charred tissue and a zone of coagulation necrosis. Analysis of lesion dimensions in groups IA and IIA showed comparable lesion depth and diameter with single continuous and paired sequential laser discharges at energies of 50 J (p greater than .2), 100 J (p greater than .2), and 150 J (p greater than .2). Similarly, lesion depth and diameter were comparable in groups IB and IIB at the same energies. We conclude that paired sequential argon laser discharges may be used to produce comparable tissue lesions to single continuous argon laser discharges in diseased human ventricle.

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PubMed1985

A prospective randomized study of the clinical efficacy and safety of transvenous cardioversion for termination of ventricular tachycardia.

The clinical efficacy and safety of transvenous cardioversion for termination of sustained ventricular tachycardia (VT) were examined by a prospective randomized study design in 22 patients (19 men, three women; mean age 64 +/- 9 years) with organic heart disease and sustained VT. Patients were randomly assigned to undergo an incremental low-energy protocol from 0.03 to 2.2 J (group A, 11 patients) or an incremental high-energy protocol from 0.5 to 10.0 J (group B, 11 patients). Transvenous cardioversion was performed during electrophysiologic studies in the control (drug-free) state and during serial antiarrhythmic drug testing in all patients. Both groups were comparable for demographic, disease and functional status, and electrophysiologic parameters. A total of 77 episodes of VT (group A, 45; group B, 32) were analyzed. The overall efficacy of transvenous cardioversion for termination of VT was 62% (group A 56% vs group B 72%; p less than .01). Antiarrhythmic drug therapy did not significantly enhance efficacy of transvenous cardioversion (control 59% vs drug 65%; p greater than .2). Stepwise discriminant analysis correlated successful transvenous cardioversion with longer VT cycle length (p less than .0005), higher energy (p less than .025), lower energy waveform tilt (p less than .025), shorter time to initial cardioversion attempt (p less than .025), and shorter QRS duration in sinus rhythm (p less than .05). Acceleration of VT was frequent (8% incidence per delivered shock). Thirty-one percent of all incremental shock protocols were terminated because of this complication. After cardioversion, transient arrhythmias were common (bradyarrhythmias 23%, supraventricular tachyarrhythmias 12%). Displacement of electrode catheters after transvenous cardioversion was uncommon (3%).(ABSTRACT TRUNCATED AT 250 WORDS)

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PubMed1985

Comparative efficacy of transvenous cardioversion and pacing in patients with sustained ventricular tachycardia: a prospective, randomized, crossover study.

We performed a prospective, randomized crossover study to evaluate the comparative efficacy of transvenous cardioversion and rapid ventricular pacing for termination of induced ventricular tachycardia in patients with spontaneous ventricular tachycardia and organic heart disease. Sixty-two episodes of ventricular tachycardia were induced in 15 patients, mean age 60 +/- 10 years, during electrophysiologic studies. All patients underwent a preselected electrical therapy protocol in a randomized crossover sequence. Transvenous cardioversion was performed by an incremental protocol of three sequential shocks (0.5, 1.1, and 2.7 J). Six asynchronous sequential bursts of rapid ventricular pacing (10 and 15 paced stimuli at 90%, 75%, and 65% of ventricular tachycardia cycle length) were used. Mean cycle length of ventricular tachycardia for the study population was 391 +/- 85 msec. The morphology of the tachycardia was left bundle branch block in 27, right bundle branch block in 32, and indeterminate in three. Characteristics of ventricular tachycardia terminated by the two techniques were comparable. Rate of success for termination of tachycardia with the two methods was also comparable (transvenous cardioversion 83%, rapid ventricular pacing 80%; p greater than .1) and these responses were concordant in 78%. The modes of termination of ventricular tachycardia were similar. The incidence of acceleration of ventricular tachycardia per episode with these preselected protocols was also comparable (transvenous cardioversion 11%, rapid ventricular pacing 6%; p greater than .2). Transient supraventricular tachyarrhythmias were more frequent after transvenous cardioversion (23%) than after rapid ventricular pacing (3%). Significant patient discomfort occurred only after transvenous cardioversion (incidence of 57%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Studies on left ventricular function during sustained ventricular tachycardia.

The acute effects of rapid ventricular pacing and sustained ventricular tachycardia on left ventricular function were examined in patients with recurrent sustained ventricular tachycardia. Programmed electrical stimulation and left ventricular hemodynamic measurements were performed in 20 patients (19 men and 1 woman), with an age range of 49 to 79 years (mean 63 +/- 9). Indexes of left ventricular function that were analyzed included left ventricular peak systolic pressure, end-diastolic pressure, first derivative of peak left ventricular pressure (dP/dt) and negative left ventricular dP/dt. Measurements were obtained during sinus rhythm, after paced premature ventricular depolarizations, during rapid ventricular pacing (cycle lengths 600 to 250 ms) and immediately after induction of sustained ventricular tachycardia. Mean left ventricular peak systolic blood pressure was 123 +/- 19 mm Hg during sinus rhythm, decreased to 77 +/- 23 mm Hg (p less than 0.05) at the induction of ventricular tachycardia and remained decreased during arrhythmia (p less than 0.01). Mean left ventricular end-diastolic pressure was 22 +/- 5 mm Hg during sinus rhythm, did not change after arrhythmia induction (22 +/- 9 mm Hg, p greater than 0.2) and remained unchanged during sustained ventricular tachycardia (p greater than 0.2). Mean peak left ventricular dP/dt was 1,400 +/- 620 mm Hg/s in sinus rhythm, decreased to 810 +/- 580 mm Hg/s (p less than 0.05) at ventricular tachycardia induction and remained decreased during sustained ventricular tachycardia (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

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