A.R. Garan

Development of a Novel Echocardiography Ramp Test for Speed Optimization and Diagnosis of Device Thrombosis in Continuous-Flow Left Ventricular Assist Devices: The Columbia Ramp Study

OBJECTIVES This study sought to develop a novel approach to optimizing continuous-flow left ventricular assist device (CF-LVAD) function and diagnosing device malfunctions. BACKGROUND In CF-LVAD patients, the dynamic interaction of device speed, left and right ventricular decompression, and valve function can be assessed during an echocardiography-monitored speed ramp test. METHODS We devised a unique ramp test protocol to be routinely used at the time of discharge for speed optimization and/or if device malfunction was suspected. The patients left ventricular end-diastolic dimension, frequency of aortic valve opening, valvular insufficiency, blood pressure, and CF-LVAD parameters were recorded in increments of 400 rpm from 8,000 rpm to 12,000 rpm. The results of the speed designations were plotted, and linear function slopes for left ventricular end-diastolic dimension, pulsatility index, and power were calculated. RESULTS Fifty-two ramp tests for 39 patients were prospectively collected and analyzed. Twenty-eight ramp tests were performed for speed optimization, and speed was changed in 17 (61%) with a mean absolute value adjustment of 424 ± 211 rpm. Seventeen patients had ramp tests performed for suspected device thrombosis, and 10 tests were suspicious for device thrombosis; these patients were then treated with intensified anticoagulation and/or device exchange/emergent transplantation. Device thrombosis was confirmed in 8 of 10 cases at the time of emergent device exchange or transplantation. All patients with device thrombosis, but none of the remaining patients had a left ventricular end-diastolic dimension slope >-0.16. CONCLUSIONS Ramp tests facilitate optimal speed changes and device malfunction detection and may be used to monitor the effects of therapeutic interventions and need for surgical intervention in CF-LVAD patients.

Ventricular arrhythmias and implantable cardioverter-defibrillator therapy in patients with continuous-flow left ventricular assist devices: Need for primary prevention?

OBJECTIVES This study sought to evaluate the prevalence and significance of ventricular arrhythmia (VA) and the role of an implantable cardioverter-defibrillator (ICD) in patients supported by a continuous-flow left ventricular assist device (CF-LVAD). BACKGROUND VAs are common in patients supported by CF-LVADs but prospective data to support the routine use of ICDs in these patients are lacking. METHODS All patients supported by long-term CF-LVAD receiving care at our institution were enrolled. The ICDs were interrogated at baseline and throughout prospective follow-up. The VA was defined as ventricular tachycardia/fibrillation lasting >30 s or effectively terminated by appropriate ICD tachytherapy. The primary outcome was the occurrence of VA >30 days after CF-LVAD implantation. RESULTS Ninety-four patients were enrolled; 77 had an ICD and 17 did not. Five patients with an ICD had it deactivated or a depleted battery not replaced during the study. Twenty-two patients had a VA >30 days after LVAD implantation. Pre-operative VA was the major predictor of post-operative arrhythmia. Absence of pre-operative VA conferred a low risk of post-operative VA (4.0% vs. 45.5%; p < 0.001). No patients discharged from the hospital without an ICD after CF-LVAD implantation died during 276.2 months of follow-up (mean time without ICD, 12.7 ± 12.3 months). CONCLUSIONS Patients with pre-operative VA are at risk of recurrent VA while on CF-LVAD support and should have active ICD therapy to minimize sustained VA. Patients without pre-operative VA are at low risk and may not need active ICD therapy.

Continuous-flow left ventricular assist devices and usefulness of a standardized strategy to reduce drive-line infections

BACKGROUND Drive-line infection (DLI) is a common complication of left ventricular assist device (LVAD) support, leading to significant morbidity that jeopardizes the benefits of these devices. It has been reported that DLI incidence is related to drive-line dressing strategies. The aim of this study was to determine whether implementation of a standardized drive-line care kit would reduce the incidence of DLIs. METHODS DLI data were collected prospectively on all LVAD patients implanted between 2009 and 2013 at Columbia University Medical Center. Drive-line care was altered on June 1, 2011, from a dry sterile dressing without a standard anchoring device to a standardized kit, which included silver gauze dressing and a standard anchoring device. The silver dressing was used until the wound incorporated, with a minimum of 1 month. RESULTS During the study period, 107 patients were implanted with LVADs before implementation of a standardized kit (Group A) and 159 thereafter (Group B). Median follow-up time (censoring at June 2011) for Group A was 8.73 (IQR 3.51 to 17.47) months and 11.65 (IQR 6.66 to 35.20) months for Group B (p = 0.17). DLI event rate improved from 0.18 to 0.07 event per patient-year, corresponding to a relative risk reduction of 62.5%. In addition, the 1-year freedom from infection was significantly increased in Group B (92.46%) compared with Group A (81.94%) (log rank = 0.036). CONCLUSION The use of a standardized kit, including silver dressing and a standard anchoring device, leads to decrease in DLI with an absolute risk reduction of 11%. Routine use of these dressing techniques is warranted based on our findings, and may lead to reduction of complications related to infections.

Early post-operative ventricular arrhythmias in patients with continuous-flow left ventricular assist devices

BACKGROUND Ventricular arrhythmias (VAs) are common in patients with a continuous-flow left ventricular assist device (CF-LVAD). The causes and clinical significance of early post-operative VAs have not previously been characterized in these patients. The purpose of this study was to assess the incidence, precipitants, and clinical impact of early VAs in patients supported by CF-LVADs. METHODS Patients with a long-term CF-LVAD receiving care between January 1, 2012, and March 1, 2014, were enrolled and followed prospectively. Implantable cardioverter-defibrillators (ICDs) were interrogated at baseline and throughout the follow-up period. VA was defined as ventricular tachycardia or ventricular fibrillation lasting >30 seconds or effectively terminated by appropriate ICD tachytherapy or external defibrillation. The primary end-point was the occurrence of early VAs (within 30 days of surgery). Secondary end-points were right ventricular (RV) failure and need for VA ablation. RESULTS There were 162 patients enrolled, and 38 (23.5%) experienced at least 1 early VA. Predictors of early VA were a history of pre-operative VAs, non-ischemic cardiomyopathy, and older age. Several conditions frequently encountered in the early post-operative period were identified as possible precipitants for VA episodes. Early VAs were associated with post-operative RV failure, particularly when patients received shocks instead of anti-tachycardia pacing. CONCLUSIONS Early VAs are common and are associated with RV failure. ICD shocks, but not anti-tachycardia pacing, for early VAs are associated with acute worsening of RV failure.

Device exchange in HeartMate II recipients: long-term outcomes and risk of thrombosis recurrence.

Successful long-term use of the HeartMate II (HM II) left ventricular assist device has become commonplace but may be complicated by mechanical failure, infection, or thrombosis necessitating device exchange (DE). A subcostal approach to device exchange with motor exchange only is less traumatic, but long-term outcomes have not been reported. A retrospective chart review of all patients who required HM II to HM II device exchange at our institution was conducted. Of the 232 HM II patients implanted between January 2008 and July 2013, 28 required 36 device exchanges during a follow-up of 33.72 ± 17.25 months. The Kaplan–Meier 1 year survival was 63% for sternotomy exchanges and 100% for subcostal exchanges. Twenty-one exchanges were performed for initial or recurring device thrombosis. Although there was no difference in the risk of subsequent thrombosis after subcostal versus sternotomy exchange, the overall risk of recurring device thrombosis after device exchange for the same was high (31%). HM II device exchange via the subcostal approach has excellent short- and long-term outcomes. Device exchange performed for thrombosis is associated with a high recurrence risk irrespective of surgical approach

Incidence and predictors of myocardial recovery on long-term left ventricular assist device support: Results from the United Network for Organ Sharing database

BACKGROUND Mechanical circulatory support (MCS) leads to favorable changes in the failing heart at the molecular, cellular, and structural levels. However, myocardial recovery leading to device explantation is rare. We reasoned that the multicenter United Network for Organ Sharing (UNOS) registry might provide insights into clinical predictors and outcomes of the recovery process. METHODS The MCS device data set of the UNOS registry was queried for patients with long-term continuous-flow left ventricular assist devices (CF-LVADs) that were explanted for heart transplantation or indication of recovery. Analysis was restricted to adult patients (≥18 years old) who were listed for an initial heart transplantation. Patients with CF-LVADs that were explanted because of recovery were compared with patients with CF-LVADs who underwent transplantation. RESULTS We identified 594 patients with HeartMate II devices and 92 patients with HeartWare devices. Duration of support was on average 500.4 ± 325.3 days. In 34 (5.0%) patients, devices were explanted secondary to myocardial recovery. Univariate predictors of recovery in patients with long-term LVADs included younger age (40 years vs 53 years), female sex, lower body mass index (25.7 kg/m(2) vs 27.9 kg/m(2)), non-ischemic etiology (91% vs 59%), lack of implantable cardioverter defibrillator at the time of listing (44% vs 79%), and lower serum creatinine (0.97 mg/dl vs 1.28 mg/dl) (all p < 0.05). In the post-explantation period, freedom from death or transplantation was 66% at 1 year. CONCLUSIONS The incidence of recovery on device support is low in the current MCS era and limited to a select cohort of predominantly young patients with non-ischemic myopathy. Given the high incidence of disease recurrence, patients should be closely followed after device explantation.

Prior hematologic conditions carry a high morbidity and mortality in patients supported with continuous-flow left ventricular assist devices

BACKGROUND Mechanical support leads to an increased risk of both bleeding and thrombotic events, but little is known about the risk of device support in patients with a baseline predisposition to these events. The aim of this study was to examine outcomes among patients with baseline hematologic conditions who underwent continuous-flow LVAD implantation (CF-LVAD). METHODS We retrospectively reviewed records of 286 patients who underwent CF-LVAD implantation at the Columbia University Medical Center between April 2008 and December 2013. Patients diagnosed with the following hematologic conditions were enrolled: idiopathic thrombocytopenic purpura (ITP); Factor V Leiden; elevated Factor VIII; heparin-induced thrombocytopenia (HIT); or undefined hypercoagulable state. RESULTS Of the 286 CF-LVAD patients implanted during the study period, 12 were considered to have a significant hematologic condition predisposing them to either bleeding or thrombotic events. The study included 5 patients with ITP, 1 with Factor V Leiden, 1 with elevated Factor VIII, 2 with HIT and 3 patients with undefined hypercoagulable state. Patients were supported for a total of 168.46 months, with a median of 10.76 months (IQR 4.78 to 21.36 months). There was a high frequency of thrombotic (0.57 event per patient-year), neurologic (0.36 event per patient-year) and bleeding (0.64 event per patient-year). Actuarial survival rates at 6 and 12 months were 81.8%, but fell to 49% at 2 years. CONCLUSIONS Patients with a history of prior hematologic conditions are at high risk for bleeding, thrombotic and neurologic events during device support, leading to early mortality. This case series questions the benefit of CF-LVAD in these patients and the appropriate management with regard to anti-coagulation. Further studies on the outcomes of these patients are warranted.

Improved outcomes from extracorporeal membrane oxygenation versus ventricular assist device temporary support of primary graft dysfunction in heart transplant

BACKGROUND Primary graft dysfunction (PGD) is one of the most common causes of early death after orthotopic heart transplantation. Mechanical circulatory support devices are required for severe forms of PGD. Venoarterial extracorporeal membrane oxygenation (VA-ECMO) and temporary ventricular assist device (VAD) support have both been reported to be useful for severe PGD. METHODS Between January 2007 and December 2015, 597 patients received a heart transplant at our center. Of those, severe PGD developed in 44 patients (7.4%), and they received a continuous-flow external VAD (n = 17) or VA-ECMO (n = 27) support within 24 hours after transplant. We compared early and late outcomes between groups. RESULTS Baseline characteristics were similar between groups. Implantation of the temporary VAD required longer cardiopulmonary bypass time compared with VA-ECMO (323 ± 86 minutes vs 216 ± 65 minutes, p < 0.0001). Patients who received a VAD were more likely to have longer support time (14 ± 17 days vs 5.2 ± 3.9 days, p = 0.011), a higher incidence of major bleeding requiring chest reexploration (77% vs 30%, p = 0.0047), and a higher incidence of renal failure requiring renal replacement therapy (53% vs 11%, p = 0.0045) after surgery. Overall hospital mortality was 27%. In-hospital mortality for VAD and VA-ECMO patients were 41% and 19%, respectively (p = 0.16). Ten patients (59%) were weaned from VAD support, and 24 (89%) were weaned from VA-ECMO support after adequate graft function recovery (p = 0.03). The 3-year post-transplant survival was 41% in the VAD group and 66% in the VA-ECMO group (p = 0.13). CONCLUSIONS For severe PGD, support with VA-ECMO appears to result in better clinical outcomes compared with VAD.

Bridge to durable left ventricular assist device for refractory cardiogenic shock

Objective: The role of short‐term mechanical circulatory support has increased in patients with refractory cardiogenic shock. However, limited data exist on the outcomes of a bridge to a durable left ventricular assist device strategy using short‐term mechanical circulatory support. Methods: We retrospectively reviewed 382 patients who underwent continuous‐flow left ventricular assist device insertion between 2004 and 2014. Of these, 45 (12%) were bridged with short‐term mechanical circulatory support devices for refractory cardiogenic shock. We analyzed early and midterm outcomes in this bridged cohort. Multivariate Cox proportional hazards modeling was performed to evaluate the predictor of overall death in the entire cohort. Results: The mean age of the bridged cohort was 53 ± 10 years, and 87% were male. The types of initial support included percutaneous devices in 24 patients (53%) and external continuous‐flow ventricular assist device in 21 patients (47%). The median duration of short‐term mechanical circulatory support was 14.0 (interquartile range, 7.5–29.5) days. The short‐term mechanical circulatory support significantly improved end‐organ function and hemodynamics. After conversion to durable left ventricular assist device insertion, in‐hospital mortality was 18%. The incidence of right ventricular assist device use was high at 27%. The overall survival was 70% and 62% at 1 and 2 years, respectively. Cox multivariate hazard analysis in the entire cohort demonstrated that the use of a postoperative right ventricular assist device was a significant predictor of overall death (hazard ratio, 4.04; P < .001; 95% confidence interval, 1.97–7.94), but the use of a short‐term mechanical circulatory support was not (P = .937). Conclusions: Short‐term mechanical circulatory support can optimize patients in refractory cardiogenic shock and serve as a bridge to implantation of a durable left ventricular assist device. However, the early mortality rate after durable left ventricular assist device implantation is high because of unrecognized right ventricular failure.

Incidence and Implications of Left Ventricular Distention During Venoarterial Extracorporeal Membrane Oxygenation Support

Left ventricular distention (LVD) during venoarterial extracorporeal membrane oxygenation (VA-ECMO) support is increasingly recognized but seldom reported in the literature. The current study defined LVD as not present (LVD−); subclinical (LVD+, evidence of pulmonary edema on chest radiograph AND pulmonary artery diastolic blood pressure greater than 25 mm Hg within the first 2 hours of intensive care unit admission); or clinical (LVD++, need for decompression of the left ventricle immediately following VA-ECMO initiation). Among 226 VA-ECMO device runs, 121 had sufficient data to define LVD retrospectively. Nine patients (7%) developed LVD++ requiring immediate decompression, and 27 patients (22%) met the definition of LVD+. Survival to discharge was similar among groups (LVD++: 44%, LVD+: 41%, LVD−: 44%). However, myocardial recovery appeared inversely related to the degree of LVD (LVD++: 11%, LVD+: 26%, LVD−: 40%). When death or transition to device was considered as a composite outcome, event-free survival was diminished in LVD++ and LVD+ patients compared with LVD−. Multivariable analysis identified cannulation of VA-ECMO during extracorporeal cardiopulmonary resuscitation (ECPR) as a risk factor for decompression (odds ratio [OR]: 3.64, confidence interval [CI]: 1.21–10.98; p = 0.022). Using a novel definition of LVD, the severity LVD was inversely related to the likelihood of myocardial recovery. Survival did not differ between groups. Extracorporeal cardiopulmonary resuscitation was associated with need for mechanical intervention.