Defibrillators are superior to antiarrhythmic drugs in the treatment of ventricular tachyarrhythmias

Anesthetic Implications for Patients With Implantable Cardioverter Defibrillators

Implantable cardioverter defibrillators have become one of the preferred methods for treating many life- threatening ventricular arrhythmias. Many tens of thou sands of these devices have been implanted and this, together with the ease of worldwide travel, has made it more likely that anesthesiologists everywhere may come into contact with these patients either for elective or emergency surgery. These patients present unique anesthetic challenges because of the combination of the device and severe underlying cardiac disease. This article presents an overview of the implantable defibril lator as it affects the anesthesiologist, including device function, device assessment, electromagnetic interfer ence, and perioperative management.

'Navius' kissing stents for coronary bifurcation stenosis, recreating a new metallic carina: an IVUS-assessed case report

We report a case of implantation of a new design of stent which allows creation of a double-hemispheric lumen for the treatment of a bifurcational stenosis. The unfavourable outcome following the implantation of this stent is described.

Inappropriate discharges by fourth generation implantable cardioverter defibrillators in patients with ventricular arrhythmias

The study prospectively investigated the incidence, cause and efficient management of inappropriate discharge by the fourth generation implantable cardioverter-defibrillator (ICD) system in 45 patients (mean age, 57+/-16 years). During the follow-up period of 27+/-17 months, 18 patients (40%) experienced one or more inappropriate therapies: sinus and supraventricular tachycardia (15 patients) and T wave oversensing (3 patients). In the 15 patients, re-programming of the tachycardia detection interval and/or additional treatment with beta-blocking agents were effective. In the 3 patients with T wave oversensing, the arrythmia was associated with an increase in T wave amplitude, change in T wave morphology and decreased R wave amplitude, and re-programming of the sensitivity of the local electrogram or changing the number of intervals to detect ventricular tachycardia decreased the number of inappropriate discharges in all 3 patients. In conclusion, inappropriate therapies are common problems in patients treated with the fourth generation ICD system, but most of them can be resolved using the dual-chamber ICD system. However, in patients with T-wave oversensing, it is difficult to avoid inappropriate discharge completely, even if the dual-chamber ICD system is implanted.

Inappropriate discharges from an intravenous implantable cardioverter defibrillator due to T-wave oversensing

This report describes the clinical management of 2 patients with ventricular fibrillation (VF) who received inappropriate shocks from an implantable cardioverter defibrillator (ICD) due to T-wave oversensing. Cardiac sarcoidosis was confirmed as the underlying heart disease in 1 patient and idiopathic dilated cardiomyopathy in the other. Within 2 months after ICD implantation, both patients received several inappropriate shocks during sinus rhythm. Stored electrograms showed decreased R-wave amplitudes and increased T-wave amplitudes. The ICD sensed both R- and T-waves as ventricular activation, which met the rate criteria for VF treatment. Reprogramming the sensing threshold in association with administration of a drug to slow the heart rate decreased the incidence of the inappropriate shocks in both patients, but these palliative measures did not completely suppress the inappropriate shocks. To avoid T-wave oversensing, the repositioning or adding of a sensing lead is required. The potential risk of T-wave oversensing in ICD patients who have small R-wave amplitudes should be recognized.

Development of ventricular fibrillations with different characteristics in the local electrocardiogram: large and small amplitude of activation, and its implication for implantable cardioverter defibrillator treatment

An implantable cardioverter defibrillator (ICD) was implanted in 2 patients with ventricular tachyarrhythmia related to old myocardial infarction, and defibrillation tests were attempted at the time of ICD implantation and at 2 or 4 weeks after the operation. Ventricular fibrillation (VF) was induced by T-wave shocks, but the amplitude of the ventricular electrogram was different in each VF. In most of the VFs with large ventricular electrograms, the local activity was appropriately detected. However, many undersensed beats were observed in other VFs that had fine ventricular electrograms and a longer time was needed before delivering the shock. The amplitude of the ventricular electrogram might be small in some cases of VF and this might result in undersensing and/or unsuccessful defibrillation. Close attention must be paid to the amplitude of ventricular activation in each VF to avoid possible difficulty in ICD therapy.

Predicting the effect of D,L-sotalol on ventricular tachycardia inducibility from the RR variability response

AIM

To find a rapid way of identifying non-responders to D, L-sotalol in patients with ventricular tachycardia.

METHODS

Programmed ventricular stimulation and RR variability were studied in the control state and 10 days after treatment with 160 to 320 mg of D,L-sotalol in 36 consecutive patients with ventricular tachycardia.

RESULTS

In 14 patients (group I) D,L-sotalol suppressed ventricular tachycardia inducibility. In 22 patients (group II) sustained ventricular tachycardia remained inducible during D,L-sotalol treatment. The ventricular tachycardia rate was slowed in eight patients and unchanged or accelerated in 14. At baseline, heart rate variability was similar in both groups. During treatment with D,L-sotalol, variables reflecting parasympathetic activity (pNN50, rMSSD, and high frequency amplitude (HF)) increased in both groups: HF increased from (mean (SD)) 75 (68) to 146 (134) in group I (p < 0.05) and from 60 (49) to 125 (79) in group II (p < 0.05). Other variables were unchanged in group I. In group II, the variables associated with sympathetic activity (coefficient of variance (CV), ratio of low frequency amplitude (LF) to HF) decreased significantly: CV decreased from 13 (4) to 9 (2) (p < 0. 001) and LF/HF from 4.74 (3.02) to 3.00 (2.02) (p < 0.05).

CONCLUSIONS

The beta blocking effect of D,L-sotalol produced a significant improvement over control values in indices of parasympathetic tone in all treated patients. However, the heart rate variability indices related to sympathetic activity were decreased only in non-responders. This effect of D,L-sotalol on heart rate variability could help detect non-responders to the drug and avoid an electrophysiological study.

Single-chamber versus dual-chamber implantable cardioverter defibrillators: indications and clinical results

The clinical benefit of standard (single-chamber) implantable cardioverter defibrillator (ICD) therapy in elderly patients or in subjects with moderate or severe heart failure who had ventricular tachyarrhythmias has been debated. We studied the follow-up of 450 patients who underwent standard ICD implantation at our institution in relation to the functional status of heart failure (New York Heart Association Class) or patient's age. During a mean follow-up of 24 +/- 28 months (range, < 1-114 months), 90 patients (23%) died: 9 patients (2%) from sudden arrhythmic death and 5 patients (1%) suddenly, but probably not from arrhythmic causes; 55 patients (14%) died from congestive heart failure and/or myocardial reinfarction and 21 patients (5%) from noncardiac causes. We could clearly demonstrate that ICD therapy was able to prevent sudden cardiac death, both in patients with severely depressed left ventricular function and in patients aged > or = 65 years. An important step forward in ICD technology was the introduction of dual-chamber pacing possibilities to improve left ventricular dysfunction and to allow a more individualized ICD therapy. At our institution, we have implanted a dual-chamber ICD in 15 patients. Preliminary results showed that heart failure improved in 5 patients (33%) and remained unchanged in 10 patients (67%, p = not significant). There were no patients who had a lesser degree of heart failure after implant. Based on our experience so far, in addition to the hemodynamic benefits of dual-chamber ICDs, dual-chamber sensing and wave-form storage capabilities are very helpful and promising diagnostic tools for the detection and handling of inappropriate ICD therapies.

Treatment of a bifurcation lesion at the anastomosis of a vein graft by true 'Y' stenting

We describe the treatment of a bifurcation lesion at the anastomosis of a vein graft by 'true Y' stenting which preserved both antegrade and retrograde flow away from the graft.

Ventricular fibrillation with small amplitude of activation and its implications for implantable cardioverter defibrillator treatment

An implantable cardioverter defibrillator (ICD) was implanted in a patient with ventricular fibrillation (VF) related to old myocardial infarction. During VF, amplitude of ventricular activation was small, and the ventricular sensitivity at 1.2 mV failed to detect several small ventricular activations. When the sensitivity was changed to 0.3 mV, both under- and oversensed beats occurred during VF, and at the ventricular sensitivity of 0.15 mV, the undersensed beats disappeared while oversensed beats markedly increased. Defibrillation test was repeated one and four weeks after the implantation, and these inappropriate beats were minimized at the ventricular sensitivity of 0.3 mV. We should pay attention to the amplitude of ventricular activation to avoid possible trouble in ICD therapy.

Implantable cardioverter-defibrillator therapy: influence of left ventricular function on long-term results

The degree of left ventricular impairment in an acknowledged important prognostic marker of long-term outcome for patients being evaluated for implantation of cardioverter-defibrillators. Just how left ventricular function impacts freedom from all-cause mortality, as well as from sudden death and cardiac death, is a subject of current major debate, and is analyzed hereunder from a large, recent multicenter ICD patient cohort. The multicenter database consists of data from 361 patients receiving implantable cardioverter-defibrillators for standard indications, that is, documented episodes of ventricular fibrillation or sustained ventricular tachycardias with poor hemodynamic toleration. Data were collected from 1988 to 1995 at three centers in Germany. Two-hundred and three patients (56%) had a left ventricular ejection fraction (LVEF) > 0.30 (group I), and 158 patients (44%) had a LVEF < or = 0.30 respectively (group II). The mean follow-up was 23.9 months (range 3-98 months). Overall survival at 5 years for group II patients was lower, as expected, at 74.1% versus 94.2%, respectively (P < 0.0001). Mortality was higher for each different cause of death in group II patients than in Group I: sudden arrhythmic deaths, 5 versus 1 (P < 0.048); nonsudden cardiac deaths, 16 versus 5 (P < 0.002); noncardiac deaths, 7 versus 2 (P < 0.03). Group II patients received a higher rate of at least one presumably appropriate shock at 86 (54.4%) versus 89 (43.8%) in group I (P < 0.05). However (and somewhat surprisingly), neither the time from ICD implantation to death, comparing only the patients who died, nor the event-free probability of appropriate shocks due to very rapid, sustained ventricular arrhythmias (> 230 beats/min), including a presumed risk of sudden arrhythmogenic death, differed between groups I and II. Sudden cardiac death was only marginally affected by LVEF (group I, 1.5% actuarial, 5-year survival 99.5%; group II, 3.1% and 95.8%, respectively). Therefore, the lower overall survival in ICD patients with LVEF < or = 0.30 resulted mainly from causes of death that cannot be directly influenced by cardioverter-defibrillator therapy. However, because group II patients had a far higher incidence of at least one ventricular tachyarrhythmia terminated by ICD shocks than group I patients, they also probably derived benefit from ICD therapy.

The AVID trial: evidence based or randomized control trials--is the AVID study too late? Antiarrhythmics Versus Implantable Defibrillators

A great body of clinical evidence has been accumulated--before and without the AVID trial--showing that implantable defibrillators prolong life better than currently available antiarrhythmic drugs. With this evidence already available, we question the validity of a trial that attempted, in effect, to place a price tag on life and quality of life.