Troubleshooting electromagnetic interference in a patient with centrifugal flow left ventricular assist device and subcutaneous implantable cardioverter defibrillator.

A 25-year-old man with severe nonischemic dilated cardiomyopathy underwent subcutaneous implantable cardioverter defibrillator (S-ICD) implant and subsequently underwent HeartWare ventricular assist device (HVAD) placement. Postoperative interrogation revealed both primary and secondary S-ICD vectors inappropriately regarded sinus rhythm as "noise," and the alternate vector significantly undersensed sinus rhythm. The S-ICD was reinterrogated using high-resolution capture to visually confirm EMI with a dominant frequency in both the primary and secondary vectors of 46.67 Hz that fell within the S-ICD operational range of 9-60 Hz. The 46.67 Hz frequency correlated with the HVAD operational speed of 2,800 RPM. The HVAD pump speed was increased from 2,800 to 3,000 RPM, resulting in a dominant frequency of 50 Hz. The notch filter is nonprogrammable in S-ICDs. However, the built-in filter is 50 Hz for countries in European time zones as opposed to 60 Hz in US time zones due to differences in the anticipated noise from electrical sources within each continent. Thus, the S-ICD time zone was reprogrammed from EST to GMT, which reduced the notch filter from 60  to 50 Hz, resulting in S-ICD successfully eliminating EMI when the patient was in a supine position. The EMI interference was still intermittently present in the upright patient position. This case demonstrates the utility of high-resolution electrogram capture to identify the source and frequency of EMI in S-ICD and offers a potential avenue to troubleshoot dominant frequency oversensing by changing the device time zone.

The HVAD Left Ventricular Assist Device: Risk Factors for Neurological Events and Risk Mitigation Strategies.

OBJECTIVES: The purpose of this study was to determine the risk factors for ischemic in hemorrhage cerebrovascular events in patients supported by the HeartWare ventricular assist device (HVAD). BACKGROUND: Patients supported with left ventricular assist devices are at risk for both ischemic and hemorrhagic cerebrovascular events. METHODS: Patients undergoing implantation with a HVAD as part of the bridge-to-transplant trial and subsequent continued access protocol were included. Neurological events (ischemic cerebrovascular accidents [ICVAs] and hemorrhagic cerebrovascular accidents [HCVAs]) were assessed, and the risk factors for these events were evaluated in a multivariable model. RESULTS: A total of 382 patients were included: 140 bridge-to-transplant patients from the ADVANCE (Evaluation of the HeartWare Left Ventricular Assist Device for the Treatment of Advanced Heart Failure) clinical trial and 242 patients from the continued access protocol. Patients had a mean age of 53.2 years; 71.2% were male, and 68.1% were white. Thirty-eight percent had ischemic heart disease, and the mean duration of support was 422.7 days. The overall prevalence of ICVA was 6.8% (26 of 382); for HCVA, it was 8.4% (32 of 382). Pump design modifications and a protocol-driven change in the antiplatelet therapy reduced the prevalence of ICVA from 6.3% (17 of 272) to 2.7% (3 of 110; p = 0.21) but had a negligible effect on the prevalence of HVCA (8.8% [24 of 272] vs. 6.4% [7 of 110]; p = 0.69). Multivariable predictors of ICVA were aspirin ≤81 mg and atrial fibrillation; predictors of HCVA were mean arterial pressure >90 mm Hg, aspirin ≤81 mg, and an international normalized ratio >3.0. Eight of the 30 participating sites had established improved blood pressure management (IBPM) protocols. Although the prevalence of ICVA for those with and without IBPM protocols was similar (5.3% [6 of 114] vs. 5.2% [14 of 268]; p = 0.99), those with IBPM protocols had a significantly lower prevalence of HCVA (1.8% [2 of 114] vs. 10.8% [29 of 268]; p = 0.0078). CONCLUSIONS: Anticoagulation, antiplatelet therapy, and blood pressure management affected the prevalence of cerebrovascular events after implantation of the HVAD. Attention to these clinical parameters can have a substantial impact on the occurrence of serious neurological events. (Evaluation of the HeartWare Left Ventricular Assist Device for the Treatment of Advanced Heart Failure [ADVANCE]; NCT00751972).

Early elevations in pump power with the HeartMate II left ventricular assist device do not predict late adverse events.

BACKGROUND: The aim of this study was to evaluate the prevalence of early pump power elevation events in patients with the HeartMate II (HMII) and its impact on subsequent development of stroke and pump thrombosis. METHODS: We analyzed >45,000 measurements of pump power and pump speed measured during the initial hospitalization period and >12,000 follow-up measurements obtained from 138 consecutive patients implanted with a HMII between January 2009 and December 2012. An early power elevation (PEL) event was defined as power ≥10 W within the first 14 post-operative days. Patients were divided into two groups: those with an early PEL event and those without (NP). RESULTS: Median follow-up duration was 316 (range 2 to 1,264) days. Twenty-seven (20%) patients had early PEL events that lasted for a total duration of 4 (range 1 to 77) hours per patient. Pump speed averaged 9,400 rpm in both groups. Although patients in the PEL group had higher median power (7.1 [6.0 to 9.9] W vs 6.7 [5.7 to 7.8] W, p < 0.001) in the immediate post-operative period, there was no difference between the two groups noted at first follow-up (6.6 [5.9 to 8.7] W vs 6.7 [5.5 to 7.7] W, p = 0.940). No differences in the prevalence of hemorrhagic stroke (4% vs 3%, p = 0.56), ischemic stroke (0% vs 4%, p = 0.41), hemolysis (7% vs 5%, p = 0.32), pump thrombosis (7% vs 4%, p = 0.21) or survival (76% at 1 year in both groups) were found between the two groups. CONCLUSIONS: In this single-center experience, PEL events that occurred early all resolved by discharge. No relationship was found between early PEL events and subsequent development of pump thrombosis, hemorrhagic stroke or ischemic stroke.