Termination Of Sustained Ventricular Tachycardia Research Articles

Type II Bidirectional Ventricular Tachycardia as a Mechanism of Termination of Sustained Ventricular Tachycardia

Type II Bidirectional Ventricular Tachycardia as a Mechanism of Termination of Sustained Ventricular Tachycardia

Amiodarone Is Poorly Effective for the Acute Termination of Ventricular Tachycardia

It is hypothesized that intravenous (IV) amiodarone is poorly effective for the acute termination of sustained monomorphic ventricular tachycardia because of the relatively slow onset of its Vaughn-Williams class III effect to prolong myocardial depolarization and the refractory period. This study is designed to determine the effectiveness and safety of IV amiodarone for the termination of sustained monomorphic ventricular tachycardia. A retrospective case series was collected at 4 urban university-affiliated hospitals from September 1996 to April 2005 after institutional review board approval with waiver of informed consent. Emergency department (ED) patients treated with IV amiodarone for ventricular tachycardia were identified by ED treatment and hospital pharmacy billing records, International Classification of Diseases, Ninth Revision discharge codes, and ECG characteristics. All consecutive patients who received at least 150 mg amiodarone in 15 minutes or less for spontaneous sustained monomorphic ventricular tachycardia were eligible for inclusion. Sustained monomorphic ventricular tachycardia was defined as a tachycardia with uninterrupted duration or rapid recurrence despite automatic internal cardiac defibrillator therapy for at least 5 minutes before amiodarone treatment, monomorphic morphology, rate greater than 120 beats/min, QRS duration greater than 120 ms, and subsequently determined to be ventricular tachycardia by ECG criteria (eg, atrioventricular dissociation), implanted device interrogation, or formal electrophysiology study. Measured outcomes included sustained termination of ventricular tachycardia within 20 minutes of initiation of amiodarone infusion and any documented adverse effects. Rates of successful termination and adverse effects and their 95% confidence intervals (CIs) were calculated. The presence or average values of potentially confounding predictors in patients with and without ventricular tachycardia termination after amiodarone were also calculated and compared. Thirty-three patients were identified and included. Five patients received electrical therapy within 20 minutes of initiation of amiodarone infusion, and the response to amiodarone was unknown. Twenty-seven of the remaining 28 patients received 150 mg amiodarone, and the rate of successful ventricular tachycardia termination was 8 of 28, 29% (95% CI 13 to 49). Two of 33 patients, 6% (95% CI 1 to 20), required direct current cardioversion for presyncope or hypotension temporally associated with amiodarone treatment. IV amiodarone, as currently administered, is relatively safe but ineffective for the acute termination of sustained ventricular tachycardia.

Efficacy of Lidocaine and a New Aqueous Formulation of Amiodarone in the Termination of Sustained Ventricular Tachycardia

Efficacy of Lidocaine and a New Aqueous Formulation of Amiodarone in the Termination of Sustained Ventricular Tachycardia

Rapid intravenous infusion of d-1 sotalol: time to onset of effects on ventricular refractoriness, and safety.

d-1 sotalol is one of the most effective antiarrhythmic agents currently available for ventricular tachyarrhythmias, but the recommended infusion rate of 10-20 min is too slow for rapid pharmacological termination of sustained ventricular tachycardia (VT) or for use during cardiac arrest. The safety of the drug and time lag from its rapid administration to onset of significant effects on ventricular refractoriness is unknown. One hundred and nine patients with a history of spontaneous and inducible sustained ventricular tachyarrhythmias were studied. d-1 sotalol (1.5 mg.kg-1) was infused over 5 min in the first 57 patients (mean age 61 +/- 13 years, mean ejection fraction 37 +/- 15%, range 15-70%). d-1 sotalol was then given over 1 min in the next 52 patients (mean age 61 +/- 12 years, mean ejection fraction 35 +/- 11%, range 18-58%). The time course of change in right ventricular effective refractory period (RVERP) was measured in 15 consecutive patients following the 5 min infusion and in all 52 patients following the bolus injection. Following the 5 min infusion, RVERP increased rapidly from a baseline of 231 +/- 17 ms, reaching a plateau of 268 +/- 23 ms at 10 min. Following the 1 min injection, RVERP increased virtually immediately from a baseline of 237 +/- 25 ms to reach a plateau of 271 +/- 31 ms at 5 min. Two patients (one in each group) developed symptomatic hypotension; both responded to volume replacement.(ABSTRACT TRUNCATED AT 250 WORDS)

Sotalol versus lignocaine for VT.

Sotalol is better than lignocaine for the acute termination of sustained ventricular tachycardia (VT).

The use of external, noninvasive pacing for the termination of ventricular tachycardia in the emergency department setting

To determine the potential usefulness of external cardiac pacing for the termination of sustained ventricular tachycardia in the emergency department setting. Five men and one woman (mean age, 57 years) who presented to the ED with a wide-complex, hemodynamically stable tachycardia that was later proven to be ventricular in origin. Each patient underwent external overdrive pacing using a modified external pacemaker at a pulse amplitude of 120 mA and a rate of 200 pulses per minute. In all six patients, external cardiac pacing was able to successfully terminate tachycardia without complication. We conclude that external noninvasive pacing may be an effective means of terminating ventricular tachycardia in the ED setting.

Characterization of spontaneous termination of sustained ventricular tachycardia associated with coronary artery disease

To characterize the change in cycle length and QRS morphology before spontaneous termination of sustained ventricular tachycardia (VT), electrocardiograms were recorded and VT cycle length measured for the periods 31 to 21 and 11 to 1 beats before termination in 55 episodes from 28 patients with coronary artery disease. Beats 31 to 21 were designated as a period of stable arrhythmia and served as a reference for changes occurring just before termination. Forty-four episodes of VT occurred in the setting of antiarrhythmic drug therapy; 11 episodes occurred in patients not treated with antiarrhythmic drugs. Variability in cycle length was indexed by the standard deviation of the mean cycle length and by the percentage of consecutive cycles varying by ≥ 40 ms (% ≥ 40 ms). There was greater variability just before termination (standard deviation of the mean cycle length, 25.8 ms; % ≥ 40 ms, 16.7%) than during the stable period (standard deviation of the mean cycle length, 8.5 ms; % ≥ 40 ms, 5.4%; p < 0.001 for both). This was true irrespective of antiarrhythmic drug use, although the differences in the standard deviation of the mean cycle length for beats 11 to 1 and for beats 31 to 21 were greater for the antiarrhythmic drug group (29.6 vs 8.9 ms, p < 0.001) than for the group not receiving antiarrhythmic drugs (11.0 vs 6.7 ms, difference not significant). No specific patterns of cycle length variability characteristic of VT termination were found. A change in QRS morphology occurred before termination in only 4 (7%) episodes of VT. In all, (1) cycle length variability increases immediately before spontaneous VT termination, although marked variability may occur without termination; (2) antiarrhythmic drugs may enhance the increase of cycle length variability at the time of termination; (3) distinct patterns of cycle length variability were infrequently seen at termination; and, (4) a change in VT morphology before termination is rare. These results may have implications for validating computer models of VT termination, for designing sensing criteria for antitachycardia devices and for increasing our understanding of antiarrhythmic drug action.

The Clinical Use of External Noninvasive Pacing in the Termination of Sustained Ventricular Tachycardia

In order to evaluate the potential use of external cardiac pacing (EXP) in the clinical termination of sustained ventricular tachycardia (VT), we attempted VT terminations in seven patients. All had recurrent sustained monomorphic ventricular tachycardia (mean rate 145 beats/min), which had previously required cardioversion. During subsequent VT episodes, all seven underwent overdrive pacing with EXP at a pulse amplitude of 120 mA, and rates of 200 pulses/min. A total of 18 of 18 episodes of VT were successfully terminated by EXP alone. In one patient, the first attempt at EXP termination of one episode of VT resulted in an acceleration of the tachycardia, which was then terminated by EXP. All patients tolerated EXP well with minimal sedation. We conclude that EXP may be an effective clinical modality for the termination of sustained monomorphic ventricular tachycardia.

Relative efficacy and safety of intravenous drugs for termination of sustained ventricular tachycardia

The relative safety and efficacy of intravenous administration of adenosine, lignocaine, disopyramide, flecainide, and sotalol for termination of stable, induced ventricular tachycardia was assessed in serial trials. Ventricular tachycardia was terminated by pacing if it persisted 10-15 min after the end of drug administration. 24 patients with recurrent ventricular tachycardia were studied. Ventricular tachycardia was terminated by a drug in 35 of 105 trials. In 6 patients no drug terminated the arrhythmia. Adenosine did not terminate tachycardia or have any serious adverse effect in any patient; both flecainide and disopyramide were significantly more effective than lignocaine, but flecainide had significantly more severe adverse effects than lignocaine. Lignocaine was the safest drug and should continue to be used as first-line drug therapy for stable ventricular tachycardia. Disopyramide should be considered as second-line treatment. DC cardioversion is necessary for unstable ventricular tachycardia, and its availability must be ensured before attempted pharmacological intervention.

Termination of sustained ventricular tachycardia by ultrarapid subthreshold stimulation in humans.

Our purpose was to investigate the efficacy, safety, and electrophysiological mechanism of ultrarapid subthreshold electrical stimulation in terminating sustained ventricular tachycardia (VT) in humans. Fifteen patients with inducible sustained hemodynamically stable VT and whose VT cycle length ranged between 295 and 440 msec (337 +/- 60 msec) were included in this study. The stimulation threshold and ventricular myocardial effective refractory period were determined during VT, and the values ranged between 0.4 and 1.2 mA (mean, 0.7 +/- 0.3 mA) and between 185 and 245 msec (mean, 225 +/- 20 msec), respectively. Trains of ultrarapid subthreshold stimulation were delivered with cycle lengths of 100 to 10 msec in decremental steps of 10 msec. A 5-second pause was allowed between each step (decrement). A 2-msec pulse width was used in all patients, and a 4-msec pulse width was also tested in eight patients. Any apparent captured beat was disregarded. In eight (53%) patients, ultrarapid subthreshold stimulation terminated VT, and in the remaining seven (47%) patients, it did not. The lowest subthreshold stimulation that effectively terminated VT was 0.05 mA. In 10 patients, the site of early activity during VT was determined by endocardial catheter mapping, and subthreshold stimulation more effectively terminated VT in eight patients when it was applied close to the site of early activity. In seven patients who underwent mapping-guided arrhythmia surgery, subthreshold stimulation was applied close to the site of early activity and successfully terminated VT. In no patient did subthreshold stimulation produce acceleration of VT or induce ventricular fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)

Termination of sustained ventricular tachycardia by external noninvasive pacing

Cardiac pacing has proven useful in the termination of sustained ventricular tachycardia (VT). In this study, the effectiveness of external noninvasive temporary pacing was compared with traditional endocardial burst ventricular pacing for the termination of sustained and hemodynamically stable VT. In 14 patients, 16 VT morphologies induced by programmed right ventricular extrastimulation were reproducibly terminated by endocardial burst pacing (3 to 9 complexes). VT cycle lengths averaged 392 ± 97 ms (standard deviation) and ranged from 300 to 690 ms. The endocardial burst pacing cycle length used to terminate VT averaged 298 ± 93 ms (range 220 to 600 ms). External burst pacing terminated 14 of 16 VT morphologies (88%). The pacing cycle length used to terminate these 14 VTs averaged 282 ± 44 ms. The number of ventricular captures ranged from 5 to 20 beats. Failure to terminate 2 VT morphologies probably represented a failure of the device to capture the ventricle. Acceleration of VT occurred in 1 patient with burst external noninvasive pacing. These observations suggest that external burst pacing may be an effective means of terminating sustained VT in some patients.

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 >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 <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 >270 msec and can reduce the need for transthoracic cardioversion. Moderate energy transvenous shocks are inadequate to rellably convert rapid VT and frequently result in VT acceleration with the lead employed in this study Alternative electrode configurations need to be evaluated.

Termination of sustained ventricular tachycardia by transesophageal atrial pacing

Transesophageal atrial recording is a valuable diagnostic tool in differentiating ventricular from supraventricular tachycardia 1,2 and for identifying mechanisms of supraventricular tachycardia. 3 The close anatomic relation between the esophagus and the posterior wall of the atria permits atrial stimulation using an esophageal electrode. Some studies have reported ventricular pacing via this route, but most studies using standard electrodes have found this unreliable. 4,5 We report 5 patients in whom we attempted to terminate sustained ventricular tachycardia (VT) by transesophageal atrial pacing.

Electrophysiologic determinants and clinical experience in termination of sustained ventricular tachycardia.

During a 19-month period, 60 patients underwent 86 procedures resulting in sustained ventricular tachycardia (VT). Pacing restored sinus rhythm in 45 procedures (52.3%). Cardioversion was required in 34 procedures (39.5%). Ventricular tachycardia was self-terminating in 7 procedures (8.1%). No procedural complication occurred. The relationship of cycle length to termination mode was assessed in 20 studies in which VT did not accelerate. The average cycle length of VT terminable by pacing was 369 msec; that of VT requiring cardioversion was 298 msec (P