Characteristics of the electrocardiogram in patients with continuous-flow left ventricular assist devices

Ventricular Arrhythmias in Left Ventricular Assist Device Patients-Current Diagnostic and Therapeutic Considerations

Left ventricular assist devices (LVAD) are used in the treatment of advanced left ventricular heart failure. LVAD can serve as a bridge to orthotopic heart transplantation or as a destination therapy in cases where orthotopic heart transplantation is contraindicated. Ventricular arrhythmias are frequently observed in patients with LVAD. This problem is further compounded as a result of diagnostic difficulties arising from presently available electrocardiographic methods. Due to artifacts from LVAD-generated electromagnetic fields, it can be challenging to assess the origin of arrhythmias in standard ECG tracings. In this article, we will review and discuss common mechanisms, diagnostics methods, and therapeutic strategies for ventricular arrhythmia treatment, as well as numerous problems we face in LVAD implant patients.

Suppression of electromagnetic interference in electroretinography from a patient with an implanted left ventricular assist device (LVAD)

PURPOSE

A left ventricular assist device (LVAD) is an implantable cardiac pump that uses a magnetically-levitating rotor to pump blood into circulation for patients with congestive heart failure. The continuous high-frequency motion of the pump can cause significant interference in electroretinography (ERG) recordings. We evaluate filtering methods to improve ERG quality in the presence of LVAD interference.

METHODS

A patient with an implanted LVAD was referred to our clinic for ERG testing on suspicion of a retinal dystrophy. Full-field ERG (ffERG) and pattern ERG (pERG) were performed according to ISCEV standards. Recordings were acquired once in full-bandwidth mode and again in low-bandwidth mode. Digital low-pass and band-stop filtering were performed to mitigate ERG interference. Post-processing was also evaluated in a control subject with no implanted device.

RESULTS

High-frequency interference was present in all ERG recordings and corresponded to the speed settings of the pump. When applied in post-processing, both low-pass and band-stop filters suppressed the interference and presented readable ERGs without affecting peak times or amplitudes. By contrast, when recording in low-bandwidth mode, the filter drop-off was not steep enough to completely remove the interference and peak delays were introduced that could not be readily corrected.

CONCLUSIONS

LVAD interference in ERG waveforms can be successfully removed using simple digital filters. If post hoc data processing capabilities are unavailable, a large amount of interference can be removed by narrowing the acquisition bandwidth and averaging additional repeats of each stimulus response.

Electrophysiologic Changes and Their Effects on Ventricular Arrhythmias in Patients with Continuous-Flow Left Ventricular Assist Devices

Ventricular arrhythmias (VAs) continue even after left ventricular assist device (LVAD) implantation. The effect of LVAD on VAs is controversial. We investigated electrophysiologic changes after LVAD and its effects on VAs development. A total of 107 implantable cardioverter-defibrillator (ICD) patients, with LVAD, were included in this study. Electrocardiographic parameters including QRS duration (between the beginning of the QRS complex and the end of the S wave), QT duration (between the first deflection of the QRS complex and the end of the T wave) corrected QT (QTc), QTc dispersion, fragmented QRS (F-QRS), and ICD recordings before, and post-LVAD first year were analyzed. All sustained VAs were classified as polymorphic ventricular tachycardia (PVT) or monomorphic VT (MVT). The QRS, QT, QTc durations, and QTc dispersion had decreased significantly after LVAD implantation (p < 0.001 for all). Also MVT increased significantly from 28.9% to 49.5% (p = 0.019) whereas PVT decreased from 27.1% to 4.67% (p = 0.04) compared to pre-LVAD period. A strong correlation was found between QT shortening and the decrease in PVT occurrence. Besides, the increase in the F-QRS after LVAD was associated with post-LVAD de nova MVT development. Finally, F-QRS before LVAD was found as an independent predictor of post-LVAD late VAs in multivariate analysis. Pre-existing or newly developed F-QRS was associated with post-LVAD late VAs, and it may be used to determine the risk of VAs after LVAD implantation.

ECG alarms during left ventricular assist device (LVAD) therapy in the ICU

BACKGROUND

In hospitalized patients with left ventricular assist device (LVAD), electrical interference and low amplitude QRS complexes are common, which could impact the accuracy of electrocardiographic (ECG) arrhythmia detection and create technical alarms. This could contribute to provider alarm fatigue and threaten patient safety.

OBJECTIVES

We examined three LVAD patients in the cardiac intensive care unit (ICU) to determine: 1) the frequency and accuracy of audible arrhythmia alarms; 2) occurrence rates of technical alarms; and 3) alarm burden (# alarms/hour of monitoring) METHODS: Secondary analysis.

RESULTS

During 593 h, there were 549 audible arrhythmia alarms and 98% were false. There were 25,232 technical alarms and 93% were for artifact, which was configured as an inaudible text alert.

CONCLUSION

False-arrhythmia and technical alarms are frequent in LVAD patients. Future studies are needed to identify both clinical and algorithm-based strategies to improve arrhythmia detection and reduce technical alarms in LVAD patients.

Electromagnetic interference between implantable cardiac devices and continuous-flow left ventricular assist devices: a review

Many patients with continuous-flow left ventricular assist devices (CF-LVAD) have other, co-existing implantable cardiac devices. While such devices often function appropriately, there is potential for electromagnetic interference (EMI). A literature review was performed to identify cases of EMI between CF-LVAD and other implanted cardiac devices to better understand their etiology, outcomes, and the strategies used to overcome such interference. The cases identified included interference between CF-LVAD and pacemakers, implantable cardioverter-defibrillators, and cardiac resynchronization therapy. The EMI reported in the current literature can be broken down into two general categories: interference leading to difficulty establishing telemetry and interference leading to impaired electrical signal sensing. Such interference led to inappropriate shock delivery in some cases. The type of interference, and thus treatments, differed and were device dependent. The strategies employed to reduce interference included metal shielding, physical manipulation to increase the distance between devices, and even exchange of the implanted device with another brand of the same class. To avoid such EMI in the future, physicians must be aware of the reported interference between certain devices, and manufacturers must work more closely to increase the compatibility of implanted cardiac devices.

Reducing ECG Artifact From Left Ventricular Assist Device Electromagnetic Interference

Background Left ventricular assist devices (LVADs) generate electromagnetic interference that causes high-frequency noise artifacts on 12-lead ECGs. We describe the causes of this interference and potential solutions to aid ECG interpretation in patients with LVAD. Methods and Results Waveform data from ECGs performed before and after LVAD implantation were passed through a fast Fourier transform to identify LVAD-related changes in the spectral profile. ECGs recorded in 9 patients with HeartMate II, HeartMate 3, and HeartWare LVADs were analyzed to identify the LVAD model-specific spectral patterns. Waveform data were then passed through digital low-pass and bandstop filters and redisplayed to evaluate the effect of filtering on LVAD-related electromagnetic interference. The spectral profile of patients with HeartMate II and HeartMate 3 LVADs demonstrated a prominent signal at the device-specific frequency of impeller rotation. In patients with the HeartMate 3 LVAD, 2 additional peaks were observed at the frequencies equivalent to the LVAD's artificial pulsatility rotational speeds. Patients with HeartWare devices demonstrated a prominent signal peak at a frequency equal to double their LVAD's set rotational speed. Applying a low-pass filter to a value below the observed frequency peak from the LVAD significantly improved the waveform tracing and quality of the ECG. Applying a speed-specific bandstop filter to remove the observed LVAD frequency peak also improved the clarity of the ECG without compromising physiological high-frequency signal components. Conclusions LVADs create impeller rotational speed-specific electromagnetic interference that can be ameliorated by application of low-pass or bandstop filters to improve ECG clarity.

Eligibility for subcutaneous implantable cardioverter-defibrillator in patients with left ventricular assist device

Purpose

The subcutaneous implantable cardioverter-defibrillator (S-ICD) could be a promising alternative to the conventional transvenous ICD in patients with LVAD due to its reduced risk of infection. However, surface ECG is altered following LVAD implantation and, since S-ICD detection is based on surface ECG, S-ICD could be potentially affected. The aim of the present study was to analyze S-ICD eligibility in patients with LVAD.

Methods

Seventy-five patients implanted with an LVAD were included in this prospective single-center study. The ECG-based screening test and the automated screening test were performed in all patients.

Results

Fifty-five (73.3%) patients had either a positive ECG-based or automated screening test. Out of these, 28 (37.3%) patients were found eligible for S-ICD implantation with both screening tests performed. ECG-based screening test was positive in 50 (66.6%) patients; automated screening test was positive in 33 (44.0%) patients. Three ECG-based screening tests could not be evaluated due to artifacts. With the automated screening test, in 9 (12.0%) patients, the test yielded no result.

Conclusions

Patients implanted with an LVAD showed lower S-ICD eligibility rates compared with patients without LVAD. With an S-ICD eligibility rate of maximal 73.3%, S-ICD therapy may be a feasible option in these patients. Nevertheless, S-ICD implantation should be carefully weighed against potential device-device interference. Prospective studies regarding S-ICD eligibility before and after LVAD implantation are required to further elucidate the role of S-ICD therapy in this population.

Electromagnetic interference from left ventricular assist devices in patients with subcutaneous implantable cardioverter-defibrillators

INTRODUCTION

Interactions of left ventricular assist devices (LVADs) with transvenous implantable cardioverter-defibrillator systems (ICDs) have been widely reported. However, less is known regarding the impact of electromagnetic interference (EMI) from LVADs on subcutaneous ICD function.

METHODS AND RESULTS

A comprehensive literature search was performed on PubMed, Cochrane central registry, and Google Scholar using the search terms "subcutaneous implantable cardioverter-defibrillator and left ventricular assist devices," "electromagnetic interference, LVAD, and subcutaneous ICD," "EMI and S-ICD," and "inappropriate shocks, LVAD, and ICD." Demographic and programming data were extracted from the reports and authors as needed. A total of seven cases of EMI in LVAD patients with subcutaneous ICD (S-ICD) devices were found. In addition three previously unreported cases from our center were included. All cases involved either a heartware ventricular assist device or HeartMate III LVAD with a pre-existing S-ICD. In all patients, both the primary and secondary vectors had inappropriate sensing due to EMI. Three patients were reprogramed to the alternate vector with appropriate sensing. The S-ICD was either inactivated or replaced with a transvenous device in six patients. A single patient was left sensing in the alternate vector. There were no reports of inability to interrogate S-ICD systems in patients with LVADs.

CONCLUSION

The risk of inappropriate shocks from LVADs should be considered in pre-existing patients with S-ICD, particularly when the heartware ventricular assist device or HeartMate III LVAD device is present. Reprogramming of the sensing vector can occasionally avoid this issue but often the S-ICD needs to be inactivated.

[Recommendations for emergency management of patients with permanent mechanical circulatory support : Consensus statement of DGTHG, DIVI, DGIIN, DGAI, DGINA, DGfK and DGK]

The prevalence of patients living with long-term mechanical circulatory support (MCS) is rapidly increasing due to improved technology, improved survival, reduced adverse event profiles, greater reliability and mechanical durability, and limited numbers of organs available for donation. Patients with long-term MCS are very likely to require emergency medical support due to MCS-associated complications (e.g., right heart failure, left ventricular assist device malfunction, hemorrhage and pump thrombosis) but also due to non-MCS-associated conditions. Because of the unique characteristics of mechanical support, management of these patients is complicated and there is very little literature on emergency care for these patients. The purpose of this national scientific statement is to present consensus-based recommendations for the initial evaluation and resuscitation of adult patients with long-term MCS.

[Device-device interaction]

With a continuous increase in the approval of cardiac implantable electronic devices (CIED), not only pacemakers (PM) and implantable cardioverter defibrillators (ICD) but especially devices for treating chronic heart failure, more and more possibilities of device-device interactions arise, which in isolated cases can lead to death of the patient. Because of the still low numbers of patients overall, there are very few scientific studies and only isolated case reports on this topic. Devices which are at risk of interaction with a previously implanted PM are wearable cardioverter defibrillators (WCD) and subcutaneous ICDs (S-ICD). These two devices both use the surface electrocardiogram (ECG) in their algorithm for detecting ventricular arrhythmia. These surface ECGs seem to be prone to unipolar pacemaker stimulation artefacts. By correct programming of implanted pacemakers in the bipolar stimulation mode it is possible to avoid ECG artefacts and inadequate treatment. In baroreceptor activation therapy (BAT) there seem to be no device interactions so far, even though this device shows substantial highly frequent artefacts in the ECG. The cardiac contractility modulation (CCM) system has also until now not shown interactions with transvenous or subcutaneous ICD devices, even though randomized trials are missing.

Subcutaneous implantable cardioverter defibrillators in patients with left ventricular assist devices: case report and comprehensive review

Background

Left ventricular assist devices (LVAD) are increasingly used in patients with advanced heart failure, many of whom have been or will be implanted with an implantable cardioverter defibrillator (ICD). Interaction between both devices is a matter of concern. Subcutaneous ICD (S-ICD) obtains its signals through subcutaneous vectors, which poses special challenges with regards to adequate performance following LVAD implantation.

Case summary

We describe the case of a 24-year-old man implanted with an S-ICD because of idiopathic dilated cardiomyopathy, severe biventricular dysfunction, and self-limiting sustained ventricular tachycardias. After the implantation of a HeartMate 3™ (Left Ventricular Assist System, Abbott) several months later, the S-ICD became useless because of inappropriate sensing due to electromagnetic interference and attenuation of QRS voltage.

Discussion

We reviewed the reported cases in PubMed about the concomitant use of S-ICD and LVAD. Seven case reports about the performance of S-ICD in patients with an LVAD were identified, with discordant results. From these articles, we analyse the potential causes for these differing results. Pump location and operating rates in LVAD, as well as changes in the subcutaneous-electrocardiogram detected by the S-ICD after LVAD implantation are related to sensing disturbances when used in the same patient.

Left ventricular assist devices and their complications: A review for emergency clinicians

INTRODUCTION

End stage heart failure is associated with high mortality. However, recent developments such as the ventricular assist device (VAD) have improved patient outcomes, with left ventricular assist devices (LVAD) most commonly implanted.

OBJECTIVE

This narrative review evaluates LVAD epidemiology, indications, normal function and components, and the assessment and management of complications in the emergency department (ED).

DISCUSSION

The LVAD is a life-saving device in patients with severe heart failure. While first generation devices provided pulsatile flow, current LVAD devices produce continuous flow. Normal components include the pump, inflow and outflow cannulas, driveline, and external controller. Complications related to the LVAD can be divided into those that are LVAD-specific and LVAD-associated, and many of these complications can result in severe patient morbidity and mortality. LVAD-specific complications include device malfunction/failure, pump thrombosis, and suction event, while LVAD-associated complications include bleeding, cerebrovascular event, infection, right ventricular failure, dysrhythmia, and aortic regurgitation. Assessment of LVAD function, patient perfusion, and mean arterial pressure is needed upon presentation. Electrocardiogram and bedside ultrasound are key evaluations in the ED. LVAD evaluation and management require a team-based approach, and consultation with the LVAD specialist is recommended.

CONCLUSION

Emergency clinician knowledge of LVAD function, components, and complications is integral in optimizing care of these patients.

Electrocardiographic changes after implantation of a left ventricular assist device - Potential implications for subcutaneous defibrillator therapy

BACKGROUND

Implantation of a left ventricular assist device (LVAD) leads to a diverse spectrum of changes on the twelve-lead surface electrocardiogram (ECG). We aimed to elucidate the changes of the surface ECG in patients after LVAD implantation potentially impacting ECG based screening tests of subcutaneous implantable cardioverter-defibrillators (S-ICD).

METHODS

Patients from 2005 until 2017 with a documented twelve-lead ECG before and after LVAD implantation were included. Baseline parameters were obtained through hospital records. The twelve-lead ECGs registered before and after LVAD implantation were analyzed.

RESULTS

From 415 patients undergoing an LVAD implantation, complete datasets were available for 253 patients. 216 patients (85%) were male. Mean age at time of LVAD implantation was 54.7 ± 12.4 years. The underlying etiology was ischemic cardiomyopathy in 119 (47%), dilated cardiomyopathy in 112 (44%), myocarditis in 8 (3%) and other in 14 (6%). We observed a reduction in the amplitude of the R wave in lead I (p < 0.0001), lead II (p < 0.0001), lead III (p < 0.004), lead aVL (p < 0.001) and lead aVF (p < 0.0001) as well as of the S wave in lead III (p < 0.001) and lead aVR (p < 0.0001) after LVAD implantation. We also noticed a reduction of the R:T ratio in lead I (p < 0.0001) as well as in lead II (p = 0.100) and lead aVF (p = 0.292) although statistically non-significant.

CONCLUSION

LVAD implantation leads to significant alterations of the surface ECG, especially the R:T ratio in leads I, II and aVF. These leads correlate with the vectors of the ECG based S-ICD screening test. Thus, these ECG changes may impact the continuous eligibility for subcutaneous ICD therapy in patients after LVAD implantation.

Left Ventricular Assist Device Management in the Emergency Department

The prevalence of patients living with a left ventricular assist device (LVAD) is rapidly increasing due to improvements in pump technology, limiting the adverse event profile, and to expanding device indications. To date, over 22,000 patients have been implanted with LVADs either as destination therapy or as a bridge to transplant. It is critical for emergency physicians to be knowledgeable of current ventricular assist devices (VAD), and to be able to troubleshoot associated complications and optimally treat patients with emergent pathology. Special consideration must be taken when managing patients with VADs including device inspection, alarm interpretation, and blood pressure measurement. The emergency physician should be prepared to evaluate these patients for cerebral vascular accidents, gastrointestinal bleeds, pump failure or thrombosis, right ventricular failure, and VAD driveline infections. Early communication with the VAD team and appropriate consultants is essential for emergent care for patients with VADs.

A Case Series of Acute Myocardial Infarction in Left Ventricular Assist Device-Supported Patients

Acute myocardial infarction (AMI) is an underrecognized phenomenon in patients with continuous-flow left ventricular assist devices (CF-LVAD). Previously, there has been an optimistic expectation of a benign clinical course; however, AMI in LVAD-supported patients can result in profound consequences and management remains controversial. We describe a case series of AMI in four CF-LVAD patients, each with a different presentation, clinical course, treatment, and outcome. The clinical variability and mixed outcomes of these patients highlights the unique challenges in diagnosis and management of AMI in this population, particularly the uncertain role of percutaneous intervention (PCI), and underscores the potentially poor prognosis of this entity. Several key points emerge from this review. First, LVAD-supported patients frequently have underlying abnormalities on the electrocardiogram (ECG) that obscure the diagnosis of AMI. Second, clinicians should have a high degree of suspicion for AMI in the presence of suggestive clinical features, elevated cardiac biomarkers, or new-onset ventricular arrhythmias. Third, the decision to proceed with PCI requires careful evaluation of the risk of hemorrhage, and strong consideration should be given to the use of bleeding avoidance strategies during and after PCI.