A case of electromagnetic interference between HeartMate 3 LVAD and implantable cardioverter defibrillator

Implantable cardioverter defibrillators (ICDs) have been shown to have a significant benefit in reducing sudden cardiac death (SCD) in patients with systolic heart failure. Additionally, cardiac devices as a bridge to transplant or destination therapy are often used in patients with end‐stage systolic heart failure. As a result, most patients with left ventricular assist devices (LVADs) also have an ICD. Here, we present an electromagnetic interference (EMI) between HeartMate 3 LVAD and ICD. This issue might be critical for both electrophysiologists and advanced heart failure cardiologists to understand prior to implantation of ICD/LVADs in these patients.     

Covering sleeves can shield the high-voltage coils from lead chatter in an integrated bipolar ICD lead.

AIMS: Integrated bipolar implantable cardioverter-defibrillator (ICD) leads use the distal high-voltage coil as both the ventricular sensing anode and the distal shocking electrode. Mechanical interactions between the distal ICD coil and other intracardiac leads have been reported to result in electrical oversensing and inappropriate ICD therapies. We sought to determine whether covering sleeves over the high-voltage coils of an integrated bipolar ICD lead could prevent sensed artefact from mechanical lead interactions. METHODS AND RESULTS: Endotak Reliance 0157 and Endotak Reliance-G 0185 leads, the latter with expanded polytetrafluoroethylene (ePTFE) sleeves covering the high-voltage coils, were connected to ICD generators and the leads were submerged in saline. Device programmers were used to communicate with the ICD generators, providing real-time electrogram recording throughout testing. A series of mechanical interactions were performed with the ICD leads, including sliding and striking each distal coil against metal and non-metal components of other ICD and pacemaker leads. All direct metal-metal interactions resulted in sensed electrical artefact, including interactions between the bare ICD coil and another bare ICD coil or metal pacemaker ring. Identical mechanical interactions where metal-metal contact was prevented due to an interposed ePTFE covering sleeve were electrically silent with no sensed artefact. CONCLUSIONS: A covering sleeve over the distal high-voltage coil of an integrated bipolar ICD lead can mechanically shield the lead from metal-metal interactions, which might otherwise result in sensed artefact and inappropriate ICD therapies or withholding of pacing output. This finding has implications for lead selection when a new ICD lead is to be implanted adjacent to abandoned intracardiac leads or lead fragments.     

Implementation of MADIT and MUSTT in Clinical Practice: Results of an International Survey

Background: The long‐awaited dramatically positive outcome of the Multicenter Automatic Defi‐brillator Implantation Trial (MADIT II), just published by Moss et al.,14 has generated cardiologists’interest on the implementation into clinical practice of that trial. Important lessons may be learned by examining the clinical implementation of two preceding randomized, prospective, prophylactic ICD trials: the original MADIT trial, published late 1996, and the Multicenter Unsustained Tachycardia Trial (MUSTT), published late 1999. Both demonstrated that implantable cardioverter defi‐brillators reduce all‐cause mortality by over 50% in high risk patients without previous sustained arrhythmias. Methods: In early 2000, we surveyed 133 active electrophysiology centers (47 American, 81 European, 5 Canadian) to determine the extent to which these practices have been implemented in clinical practice during 1999, and the responses were compared to a similar survey for the year 1998. Results: ICDs implanted for MADIT or MUSTT criteria accounted for 18% of new ICD implants in 1999, 65% greater than in 1998, increasing from 6% to 11% in Europe, and from 15% to 24% in America. During 1999, 53% of patients receiving ICDs for these indications were inpatients identified during hospitalization, 27% were outpatients referred specifically for MADIT/MUSTT indications, and 20% were identified by routine screening. Per the survey, in 1999 68% of responders were “somewhat 10–20%)” and 14% were “considerably (>20%)” more likely to implant ICDs for all indications. Conclusions: Extrapolating the results of this survey to all initial ICD implants for 1999, we estimate that 8500 implants for MADIT/MUSTT criteria took place in 1999, with the overall number of such implants substantially increased over the previous year, irrespective of geographic location, and influenced significantly by the publication of MUSTT. However, screening and implant practices between centers continue to vary over a broad spectrum. It will be interesting to observe whether similar patterns will follow with MADIT II. A.N.E. 2002;7(4):399–405     

Over the wire lead extraction and focused force venoplasty to regain venous access in a totally occluded subclavian vein

Introduction  Venoplasty allows the addition or replacement of leads despite subtotal or total subclavian occlusion. Methods  The threshold of the LV pacing lead implanted for biventricular pacing over a period of 18 months increased to greater than 5 V. A pre implant venogram revealed total subclavian occlusion. Venous access was maintained by extraction of the 4 F LV lead over a wire. Subsequently the sheath would not advance despite 6mm balloon inflation to 30 atm with no residual waist. A wire was placed beside the balloon and the balloon was reinflated. Results  The subclavian obstruction was eliminated without damage to the existing leads. Conclusion  The obstruction formed by the fibrous track around an extracted lead may persist despite what appears to be successful balloon dilation. Inflation with a wire beside the balloon increases the effect eliminating the resistant obstruction without damaging the leads. Acknowledgements of Sources of Financial Support:Dr. Worley receives compensation in various forms from Medtronic, Pressure Products, Guidant, and St Jude Medical. Dr. Gohn receives compensation in various forms from Medtronic. No financial support was provided for the creation of this case report     

Implantable defibrillator event rates in patients with unexplained syncope and inducible sustained ventricular tachyarrhythmias: a comparison with patients known to have sustained ventricular tachycardia

OBJECTIVES

To assess the clinical significance of inducible ventricular tachyarrhythmias among patients with unexplained syncope.

BACKGROUND

Induction of sustained ventricular arrhythmias at electrophysiology study in patients with unexplained syncope and structural heart disease is usually assigned diagnostic significance. However, the true frequency of subsequent spontaneous ventricular tachyarrhythmias in the absence of antiarrhythmic medications is unknown.

METHODS

In a retrospective case-control study, the incidence of implantable cardiac defibrillator (ICD) therapies for sustained ventricular arrhythmias among patients with unexplained syncope or near syncope (syncope group, n = 22) was compared with that of a control group of patients (n = 32) with clinically documented sustained ventricular tachycardia (VT). Sustained ventricular arrhythmias were inducible in both groups and neither group received antiarrhythmic medications. All ICDs had stored electrograms or RR intervals. Clinical variables were similar between groups except that congestive cardiac failure was more common in the syncope group.

RESULTS

Kaplan-Meier analysis of the time to first appropriate ICD therapy for syncope and control groups produced overlapping curves (p = 0.9), with 57 ± 11% and 50 ± 9%, respectively, receiving ICD therapy by one year. In both groups, the induced arrhythmia was significantly faster than spontaneous arrhythmias, but the cycle lengths of induced and spontaneous arrhythmias were positively correlated (R = 0.6, p < 0.0001). During follow-up, three cardiac transplantations and seven deaths occurred in the syncope group, and two transplantations and five deaths occurred in the control group (36-month survival without transplant 52 ± 11% and 83 ± 7%, respectively, p = 0.03).

CONCLUSIONS

In patients with unexplained syncope, structural heart disease and inducible sustained ventricular arrhythmias, spontaneous sustained ventricular arrhythmias occur commonly and at a similar rate to patients with documented sustained VT. Thus, electrophysiologic testing in unexplained syncope can identify those at risk of potentially life-threatening tachyarrhythmias, and aggressive treatment of these patients is warranted.     

Implantable Cardioverter-Defibrillators in Children and Adolescents With Brugada Syndrome

Background

Young patients presenting with symptomatic Brugada syndrome have very high risks for ventricular arrhythmias and should be carefully considered for implantable cardioverter-defibrillator (ICD) placement. However, this therapy is associated with high rates of inappropriate shocks and device-related complications.