Azygos vein lead implantation: a therapeutic option for elevated defibrillation threshold

Abstracts

A avaliação do limiar de desfibrilação (DFT) durante o implante do cardioversor-desfibrilador (CDI) é uma etapa relevante do procedimento, uma vez que, em até 16% dos pacientes, podemos encontrar elevados DFT. Relatamos o caso de um paciente portador de cardiomiopatia dilatada (CMPD) idiopática submetido a implante de CDI biventricular. Durante o procedimento, apresentou elevado DFT e se mostrou resistente às modalidades terapêuticas usuais. Optamos pelo implante de eletrodo de desfibrilação em veia ázigos, com resolução do quadro.

Desfibriladores implantaveis; cardiomiopatia dilatada; veia ázigos; eletrodos implantados

CASE REPORT

Azygos vein lead implantation: a therapeutic option for elevated defibrillation threshold

Luiz Eduardo Montenegro Camanho^{I, II}; Antonio Carlos Botelho da Silva^I; Marco Antonio Teixeira^I; Luiz Antonio Inácio Oliveira Junior^{I, II}; Eduardo Benchimol Saad^II; Marcelo da Costa Maia^I

^IHospital São José do Avaí Itaperuna, RJ

^IIHospital Pró-Cardíaco, Botafogo, RJ - Brasil

Correspondence to

RESUMO

The evaluation of the defibrillation threshold (DFT) during the implantation of a cardioverter-defibrillator (ICD) is an important stage of the procedure, as a high DFT can be found in up to 16% of patients. We report a patient with idiopathic dilated cardiomyopathy (DCM) submitted to a biventricular ICD implantation. During the procedure, the patient showed a high DFT and showed to be resistant to usual therapeutic modalities. We opted for the azygos vein defibrillation lead implantation, with good resolution.

Keywords: Defibrillators implantable; cardiomyopathy dilated; azygos vein; electrodes implanted

Introduction

ICD implantation is a well-established therapeutic option to prevent cardiac SD in patients at risk¹. Recent data suggest that, during implantation, 6% to 16% of patients show high DFT². Such a condition is defined when the DFT value is < 10 joules in relation to the maximum generator load. Given this situation, the available strategies would be the repositioning of the electrode in the right ventricle (RV), changing the shock vector or the implantation of an additional defibrillation electrode. The defibrillation lead implantation in the azygos vein is a therapeutic option, with a small number of cases having been reported in the literature ^3,4.

Case Report

The patient was a 37-year-old male with a history of idiopathic DCM and NYHA functional class III (NYHA) despite optimized drug therapy. He had a history of syncope without prodrome. The basal echocardiogram (ECG) showed sinus rhythm with complete LBBB (QRS: 180 ms) and a PR interval of 190 ms. The ECG showed severe LV systolic dysfunction with grade III diastolic dysfunction, LA: 45 mm, LVEF 17% (Simpson), LVEDD: 90 mm, LVESD: 83 mm, moderate MI, with signs of intraventricular dyssynchrony by tissue Doppler and delay in the contraction of the posterolateral wall of the left ventricle (LV). The 24-hour Holter monitoring showed episodes of nonsustained ventricular tachycardia. Thus, he was referred for implantable cardioverter-defibrillator resynchronization (Concerto - Medtronic).

The procedure was started with an incision in the left chest region and by making a subcutaneous pocket. Soon after that, three left axillary vein punctures were performed. The defibrillation lead was positioned in the mid RV septal region. The coronary sinus was cannulated and an angiogram was performed, demonstrating the presence of a posterolateral branch, where the left ventricular electrode was positioned. The atrial lead was then positioned in the anterior wall of the RA. A defibrillation test was carried out through induction (shock on T) of ventricular fibrillation (VF) with a shock of 15, 25 and 35 J, without success, requiring external defibrillation (ED) with biphasic 200 J shock.

We chose to reposition the electrode in the inferior wall of the RV. A new defibrillation test was performed, without success, being necessary to use ED with 200 J. A new defibrillation test was performed with a reversed shock vector, once again without success. Given the impossibility of reversion with maximum load after several attempts, we decided to implant the electrode in the azygos vein. The axillary vein puncture was performed with a JL catheter, identified the azygos vein ostium, which is easily cannulated with a long 10 F sheath and a slight increase in the time of procedure (Figure 1).

A double defibrillation electrode - "coil" (Sprint Four - Medtronic) - was introduced into that vein and positioned posteriorly to the heart (Figure 2). The "coil" at the tip of the electrode of the RV, the distal "coil" of the azygos vein and the generator were programmed to perform a new test. Through VF induction, reversal was achieved only with 35 J. The patient showed stable improvement and was discharged after 36 hours. After 3 months of implantation, the patient has appropriate therapy (shock) by rapid ventricular tachycardia (VF zone).

Discussion

Although it represents an effective therapy, the experience with ICD use has shown cases of SD due to ineffective defibrillation¹. The evaluation of the DFT has become a usual procedure during ICD implantation, with the DFT being defined as the lowest amount of energy delivered by the ICD to successfully resolve two episodes of induced VF. This can be measured by several techniques, and, ideally, there must be a safety margin of 10 J for defibrillation⁵. There are few published data that support the real need to obtain an adequate DFT, although it is desirable to achieve a satisfactory margin of safety.

Birnie et al.⁶ published a series of 19,067 patients submitted to ICD implantation, showing that 35 of these patients had prolonged cardiac arrest or cerebrovascular accident, of which 9 died or had neurological sequelae, representing a rate of complications of 0.18%. These data raise the concern of the need for routine defibrillation testing. The discussion focus on patients undergoing ICD implantation for primary prevention of SD related to LV dysfunction (patients with MADIT-II or SCD-HeFT criteria)⁷. For this profile of patients, it is particularly difficult to justify potentially lethal complications, although they are rare.

Several factors are associated with a high DFT, including large body surface area, nonischemic dilated cardiomyopathy, functional class III / IV (NYHA), reduced ejection fraction, previous therapy with amiodarone, implant on the right side, ischemia and hypoxia ^8,9 .

In 2004, Cesario et al.³ described the first case of implantation of an azygos vein defibrillation lead. The improvement in defibrillation efficacy is likely to occur due to a posterior displacement of the shock vector, encompassing a larger myocardial mass. Cooper et al.⁴, in turn, published a series of nine cases of ICD implant positioning the defibrillation "coil" in azygos vein, being successful in 90% of implants.

We believe that the choice of implanting a defibrillation lead in the azygos vein should always be considered for cases with high DFT, as it is a technically feasible and safe procedure with a high probability of reducing DFT.

Potential Conflict of Interest

No potential conflict of interest relevant to this article was reported.

Sources of Funding

There were no external funding sources for this study.

Study Association

This study is not associated with any post-graduation program.

References

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• 3. Cesario D, Bhargava M, Valderrábano M, Fonarow GC, Wilkoff B, Shivkumar K. Azygous vein lead implantation: a novel adjunctive technique for implantable cardioverter defibrillator placement. J Cardiovasc Electrophysiol. 2004;15(7):780-3.
• 4. Cooper JA, Latacha MP, Soto GE, Garniany RG, Gleva MJ, Chen J, et al. The azygous defibrillator lead for elevated defibrillation thresholds: implant technique, lead stability, and patient series. Pacing Clin Electrophysiol.2008;31(11):1405-10.
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• 7. Lubinski A, Lewicka-Nowak E, Zienciuk A , Krolak T, Kempa M, Pazdyga A, et al. Clinical predictors of defibrillation threshold in patients with implantable cardioverter-defibrillators. Kardiol Pol. 2005; 62(4): 323-8.
• 8. Daubert JP, Zareba W, Hall WJ, Schuger C, Corsello A, Leon AR, et al. Predictive value of ventricular arrhythmia inducibility for subsequent ventricular tachycardia or ventricular fibrillation in Multicenter Automatic Defibrillator Implantation Trial (MADIT) II patients. J Am Coll Cardiol. 2006;47(1):98-107.
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Publication Dates

• Publication in this collection
  08 Aug 2012
• Date of issue
  June 2012

History

• Received
  07 June 2011
• Accepted
  02 Dec 2011
• Reviewed
  04 July 2011