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.

Left Ventricular Decompression During Speed Optimization Ramps in Patients Supported by Continuous-Flow Left Ventricular Assist Devices: Device-Specific Performance Characteristics and Impact on Diagnostic Algorithms.

BACKGROUND: Echocardiographic ramp tests have been widely used to help guide speed adjustments and for identification of potential device malfunctions in patients with axial continuous-flow left ventricular assist devices (LVADs) (Heartmate II LVAD [HMII]). Recently, the use of centrifugal-flow LVADs (Heartware LVAD [HVAD]) has been on the rise. The purpose of this study was to evaluate the utility of ramp tests for assessing ventricular decompression in HVAD patients. METHODS AND RESULTS: In this prospective study, ramp tests were performed before index hospitalization discharge or at the time of device malfunction. Vital signs, device parameters (including flow), and echocardiographic parameters (including left ventricular end-diastolic dimension [LVEDD], frequency of aortic valve [AV] opening, and valvular insufficiency) were recorded in increments of 100 rpm, from 2,300 rpm to 3,200 rpm. Twenty-six ramp tests were performed, 19 for speed optimization and 7 for device malfunction assessment. The average speed after the speed optimization ramp tests was 2,534.74 ± 156.32 RPM, and the AV closed at a mean speed of 2,751.77 ± 227.16 rpm, with 1 patient's valve remaining open at the maximum speed. The reduction in LVEDD for each speed increase was significantly different when the AV was open or closed, at -0.09 cm/increment and -0.15 cm/increment, respectively (P = .013), which is significantly different than previously established HMII LVEDD slopes. There were also significant changes in overall device flow (P = .001), upper flow (P = .031), and lower flow (P = .003) after AV closure. The power slope did not change significantly after the AV closed (P = .656). Five of the 19 tests were stopped before completion owing to suction events, but all tests reached ≥3,000 rpm. CONCLUSIONS: The parameter slopes for the HMII cannot be directly applied to ramp studies in HVAD patients. Overall, the LVEDD slope is drastically smaller in magnitude than the previously reported HMII findings, and speed adjustments were not based on the degree of left ventricular unloading. Therefore, the slope of the LVEDD-rpm relationship is not likely to be helpful in evaluating HVAD function.

Correlation Between Home INR and Core Laboratory INR in Patients Supported with Continuous-Flow Left Ventricular Assist Devices.

It has been well established that patient self-testing (PST) of international normalized ratio (INR) using home monitoring devices increases the average therapeutic time and patient satisfaction. Long-term anticoagulation therapy with warfarin is used in patients with continuous-flow left ventricular assist device (CF-LVAD) to minimize the occurrence of thromboembolic events; however, PST devices have never been tested in patients with CF-LVADs. The purpose of this study was to determine the reliability of the PST device Alere INRatio 2 in patients supported with CF-LVADs. A correlation study was performed in 50 patients with CF-LVAD who were on stable warfarin therapy for a minimum of 3 weeks. Simultaneous INR values were determined from capillary whole blood samples using the Alere PST device and venous blood samples processed in the core laboratory at Columbia University Medical Center. There was a moderate correlation between the venous and the capillary INR values with a correlation coefficient of 0.83. The median difference between the methods was 0.39, with 44 of 50 patients recording higher INRs with Alere. Results remained unchanged after adjusting for use of amiodarone, abnormal hematocrit and liver enzymes, creatinine, and thyroid-stimulating hormone. Point of care testing with Alere correlates moderately well but consistently overestimates INR when compared with conventional laboratory testing in patients with CF-LVAD.

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.

Catheter ablation for ventricular tachyarrhythmias in patients supported by continuous-flow left ventricular assist devices.

Ventricular arrhythmias (VAs) are common after implantation of a left ventricular assist device (LVAD) and in a subset of patients may be refractory to medication. Morbidity from VA in this population includes right ventricular failure (RVF). We sought to evaluate the efficacy of catheter ablation for VA in patients with LVAD. A retrospective analysis of patients supported by continuous-flow LVAD referred for catheter ablation of ventricular tachycardia (VT) between 2008 and the present was performed. Seven patients were referred for VT ablation an average of 236 ± 292 days after LVAD implantation. Three patients (42.9%) developed RVF in the setting of intractable arrhythmias. A transfemoral approach was used for six patients (85.7%) and an epicardial for one patient (14.3%). The clinical VT was inducible and successfully ablated in six patients (85.7%). The location of these arrhythmias was apical in three cases (42.9%). A total of 13 VTs were ablated in seven patients. Although the majority had reduction in VA frequency, recurrent VAs were observed in six patients (85.7%). One patient (14.3%) experienced a bleeding complication after the procedure. For patients with a high VA burden after LVAD implantation, VT ablation is safe and feasible, but VA frequently recurs.

Acute mechanical circulatory support for fulminant myocarditis complicated by cardiogenic shock.

In fulminant myocarditis complicated by cardiogenic shock, early mechanical circulatory support (MCS) may prevent cardiomyopathy and death. We sought to examine the outcomes of patients with fulminant myocarditis supported with MCS. A retrospective review of patients with acute cardiogenic shock treated with MCS from 2007 to 2013 was conducted, and patients with a diagnosis of fulminant myocarditis were included in this series. At our center, 260 patients received MCS for acute cardiogenic shock, and 11 were implanted for fulminant myocarditis. Eight received the Centrimag biventricular assist device (BIVAD), and three received veno-arterial extracorporeal membrane oxygenator (VA ECMO), though 1 VA ECMO-supported patient was transitioned to BIVAD due to refractory shock. The mean acute support time was 14.7 ± 4.4 days. Two patients required long-term left ventricular assist devices and were further supported for 55 and 112 days. Eight patients recovered with a mean ejection fraction of 54 ± 7 %, and one was successfully transplanted. Eight patients survived to discharge (73 %) with mean follow-up: 292.6 ± 306.8 days. All three deaths were due to neurologic complications. MCS should be considered in patients with fulminant myocarditis complicated by shock. With aggressive medical therapy, early utilization of MCS carries promising outcomes.

Endoluminal treatment of peripheral chronic total occlusions using the Crosser® recanalization catheter.

PURPOSE: Revascularization of lower extremity chronic total occlusions (CTOs) is technically challenging. The Crosser® recanalization catheter was designed to facilitate distal vessel intraluminal entry that is both rapid and safe. We present our experience with the Crosser device as primary therapy for peripheral CTOs. METHODS: Subjects undergoing evaluation for arterial insufficiency at our institution between 2008-2010 who were noted to have a CTO in the lower extremity by duplex ultrasonography and who subsequently underwent Crosser recanalization were enrolled. Clinical characteristics, ankle-brachial indices, Rutherford-Becker symptom category, and angiographic CTO parameters were collected. Primary technical success was intraluminal delivery of the guidewire into the distal vessel solely by the Crosser device. Secondary technical success was assisted delivery using the Outback LTD® re-entry device. Safety endpoints were the occurrence of dissections, thromboembolism, and perforations related to the Crosser device. Statistical analysis was performed to find independent predictors for failure to achieve Crosser recanalization. RESULTS: Fifty-six subjects with 73 CTOs were enrolled. The mean Crosser use time was 17.6 ± 12.7 minutes. The overall primary and secondary technical success rates for Crosser recanalization were 76.7% and 87.7%, respectively. Technical success was highest for CTOs located in the aorto-iliac (90.0%) and tibial (95.2%) arterial segments. There were no perforations related to the Crosser device. For successful cases, the mean ABI improved significantly from pre- to post-intervention (0.57 ± 0.13 to 0.89 ± 0.15, p < 0.001). The only predictors for failure were lesion length longer than 100 mm (p = 0.04) and calcification within 10 mm of the exit cap (p = 0.02). CONCLUSION: The Crosser device is safe and shows excellent efficacy in facilitating guidewire distal lumen entry, especially for aorto-iliac and tibial occlusions. The technical success rate for the femoral and popliteal occlusions is comparable to those reported with other recanalization techniques.

Study to determine the clinical significance of HEmolysis During Orbital AtheRectomy (CLEAR study).

PURPOSE: To evaluate the incidence of clinically evident hemolysis associated with orbital atherectomy used to treat severe peripheral artery disease. METHODS: The observational CLEAR study enrolled 31 subjects (16 men; mean age 71 ± 10 years, range 44-92) with claudication (58.1%) or critical limb ischemia (38.7%) who underwent orbital atherectomy with the Diamondback 360 system at 4 US centers. The 42 lesions in 31 limbs were located in the superficial femoral (n = 19, 45.2%), popliteal (n = 8, 19.0%), and tibial arteries (n = 15, 35.8%). The majority of lesions (34, 81.0%) were de novo; moderate or severe calcification was identified in 90.5% of cases. Lesion and procedural parameters were analyzed at a core laboratory. Blood samples were collected during and post procedure and analyzed for markers of hemolysis. The primary endpoint was the occurrence of clinically significant hemolysis. The secondary endpoints included the occurrence of any clinical symptoms/signs potentially related to hemolysis. Statistical analysis was performed to identify predictors for hemolysis. RESULTS: Laboratory evidence of hemolysis was seen in 11 (35.5%) subjects. No one met the clinical event criteria, and so the primary endpoint of the study was not reached. The secondary endpoints were hypertensive crisis (1, 3.2%) and transient hemoglobinuria (3, 9.7%). Lower glomerular filtration rates, calcified plaque, long atherectomy runs, and solid crown selection were independent predictors of hemolysis. CONCLUSION: There was no clinically significant hemolysis after orbital atherectomy. The results of this study will enable users to predict conditions that predispose to high levels of red cell hemolysis following orbital atherectomy and to take appropriate measures to limit its occurrence.

Orbital atherectomy for symptomatic lower extremity disease.

BACKGROUND: Plaque-debulking technologies have been proposed as alternative treatment options for peripheral arterial disease. Orbital atherectomy (OA), using the DiamondBack360 device, has emerged as one promising modality. METHODS: We evaluated the safety and efficacy of OA in the first 200 lesions treated at our institution. Patient demographics, clinical characteristics, and lesion and procedural variables were collected and analyzed. The primary safety endpoint was the 30-day major adverse events (MAE), including death, myocardial infarction, stroke, unplanned amputation, or target lesion revascularization. Other safety endpoints included access-site complications, occurrence of dissections, perforations, distal embolization, spasm, and hemolysis. The efficacy endpoints were procedural success, need for adjunctive therapy, and improvement in ankle-brachial index. Multivariate analysis was performed to find independent predictors of the safety endpoints. RESULTS: One hundred seventeen (58.5%) lesions were femoral, 31 (15.5%) were popliteal, and 52 (26.0%) were tibial. The procedural success (residual stenosis ≤30%) was comparable between the femoral and tibial lesions (86.3% vs. 92.5%, P = 0.18), but significantly lower for the popliteal lesions when compared with femoral and tibial (64.7% vs. 86.3%, P = 0.058, and 64.7% vs. 92.5%, P = 0.007 respectively). MAE at 30-days occurred in 3 (2.2%) procedures, and major access-site complications also occurred in 3 (2.2%). There were 31 (15.5%) dissections; independent predictors were diabetes mellitus (OR: 7.3, P = 0.008), crown-to-RVD ratio <0.6 (OR: 11.6, P = 0.005), and atherectomy time >360 sec (OR: 11.8, P = 0.001). There were 2 (1.0%) distal embolizations, 6 (3.0%) arterial spasms, and no perforations. Laboratory evidence of hemolysis was noted in 33.8% of cases. CONCLUSION: Orbital atherectomy allows for a significant procedural success, limited need for stenting, and favorable safety profile.

Histopathologic changes of the radial artery wall secondary to transradial catheterization.

OBJECTIVE: The immediate effects of transradial access on the radial artery wall are unknown. In this study we sought to assess the histological changes induced by catheterization on the radial artery. METHODS: Thirty-four patients undergoing coronary artery bypass grafting (CABG) had radial arteries harvested to serve as bypass conduits. The proximal and distal ends of the radial artery conduits were sectioned and embedded in paraffin. Both ends of all specimens were evaluated by a blinded pathologist for intimal hyperplasia, medial inflammation, medial calcification, periarterial tissue or fat necrosis, adventitial inflammation, adventitial necrosis, and adventitial neovascularization. Fisher's exact test was used for statistical analysis. RESULTS: Fifteen previously catheterized radial arteries (TRA group) were compared with 19 noncatheterized arteries (NCA group). The distal ends of the TRA group showed significantly more intimal hyperplasia (73.3% vs 21.1%; p = 0.03), periarterial tissue or fat necrosis (26% vs 0%; p = 0.02), and more adventitial inflammation (33.3% vs 0%; p = 0.01) than the distal ends of the NCA group. The distal ends of the TRA group also showed significantly more intimal hyperplasia (73.3% vs 26.6%; p = 0.03) and adventitial inflammation (33.3% vs 0%; p = 0.01) than the proximal ends of the same arteries. There were no histological differences in the proximal ends of the two groups. CONCLUSION: Transradial catheterization induces significant histological changes suggestive of radial artery injury limited to the puncture site in the form of intimal hyperplasia, medial inflammation, and tissue necrosis. Both the proximal and distal ends of the radial artery show a spectrum of atherosclerotic changes independent of its use for transradial catheterization.