Kerry A. Morrison

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

OBJECTIVESnThis study sought to develop a novel approach to optimizing continuous-flow left ventricular assist device (CF-LVAD) function and diagnosing device malfunctions.nnnBACKGROUNDnIn 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.nnnMETHODSnWe 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.nnnRESULTSnFifty-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.nnnCONCLUSIONSnRamp 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.

Device thrombosis in HeartMate II continuous-flow left ventricular assist devices: A multifactorial phenomenon

BACKGROUNDnContinuous-flow left ventricular assist devices (CF-LVADs) are increasingly used to support patients with advanced heart failure (HF). Device thrombosis is a serious complication of CF-LVADs, but its precise prevalence and etiology remains uncertain.nnnMETHODSnRoot-cause analysis was performed in all cases with device thrombosis confirmed upon explant among patients implanted with a HeartMate II (HM II) from January 1, 2009 to November 15, 2012. Cannula position and bend relief integrity were assessed and charts were reviewed with particular attention to anti-coagulation and infection profiles.nnnRESULTSnNineteen of 177 patients (11%) were found to have device thrombosis of various etiologies after a mean of 351 ± 311 days, representing 0.12 event/patient-year. Of the 5 mechanically induced thromboses, proximate etiology was severely abnormal inflow cannula position in 3 patients and bend relief disconnect with deformed outflow graft in 2 patients. One patient had a hypercoagulable disorder with prior arterial embolism. In the remaining 13 patients (age 61 ± 14 years, 77% male, 69% Caucasian), non-mechanical device thrombosis occurred after 357 ± 383 days; INR at the time of diagnosis was 1.81 (1.62 to 2.07); and mean device speed was 8,855 ± 359 rpm. Five of 13 patients (38%) had an infection during the month leading up to device thrombosis. Of note, lactate dehydrogenase (LDH) was already elevated at the time of discharge in patients who would later develop non-mechanical device thrombosis (423 [354 to 766] vs 352 [272 to 373] U/liter, p < 0.01).nnnCONCLUSIONSnDevice thrombosis is a multifactorial phenomenon, and differentiation of mechanical and non-mechanical causes is an essential step for individual diagnosis and treatment plans. Larger studies excluding patients with obvious mechanical etiology are needed to investigate biologic and/or management-related risk factors for device thrombosis. Our findings suggest that LDH may be an early risk marker. Due to the difficulty in treating late-stage device thrombosis, we suggest early use of simple tests to rule out both causes of thrombosis, such as X-rays and closer LDH monitoring (bi-weekly).

Prevalence, Significance, and Management of Aortic Insufficiency in Continuous Flow Left Ventricular Assist Device Recipients

Background— Aortic insufficiency (AI) is increasingly recognized as a complication of continuous flow left ventricular assist device support; however, its long-term prevalence, clinical significance, and efficacy of potential interventions are not well known. Methods and Results— We studied the prevalence and management of AI in 232 patients with continuous flow left ventricular assist device at our institution. Patients with aortic valve (AV) surgery before left ventricular assist device implantation were excluded from analysis. To examine the prevalence of de novo AI, patients without preoperative AI were divided into a retrospective and a prospective cohort based on whether a dedicated speed optimization study had been performed at the time of discharge. Forty-three patients underwent AV repair at the time of implant, and 3 subsequently developed greater than mild AI. In patients without surgical AV manipulation and no AI at the time of implant, Kaplan–Meier analysis revealed that freedom from greater than mild de novo AI at 1 year was 77.6±4.2%, and that at least moderate AI is expected to develop in 37.6±13.3% after 3 years. Nonopening of the AV was strongly associated with de novo AI development in patients without prospective discharge speed optimization. Seven of 21 patients with at least moderate AI developed symptomatic heart failure requiring surgical intervention. Conclusions— AI is common in patients with continuous flow left ventricular assist devices and may lead to clinical decompensation requiring surgical correction. The prevalence of AI is substantially less in patients whose AV opens, and optimized loading conditions may reduce AI prevalence in those patients in whom AV opening cannot be achieved.

Ventricular assist device support as a bridge to heart transplantation in patients with giant cell myocarditis

Giant cell myocarditis (GCM) carries a poor prognosis and many patients require end‐stage therapies. This study sought to determine the outcome of patients bridged with ventricular assist devices (VAD) to orthotopic heart transplantation (OHT).

Adrenergic Activation, Fuel Substrate Availability, and Insulin Resistance in Patients With Congestive Heart Failure

OBJECTIVESnThis study sought to investigate plasma levels of glucose and free fatty acids (FFA) and their relationship with adrenergic activation and insulin resistance (IR) in patients with advanced congestive heart failure (CHF).nnnBACKGROUNDnAdrenergic activation and IR are hallmarks of advanced heart failure. The resulting changes in fuel substrate availability and their implications for exercise capacity have not been elucidated.nnnMETHODSnSubjects with CHF underwent maximal exercise testing. Plasma glucose, FFA, insulin, and norepinephrine (NE) levels were measured at rest and at peak exercise. Beta-receptor sensitivity to NE was assessed using the Chronotropic Responsiveness Index (CRI). Homeostasis Model Assessment Index >2.5 defined IR. Left ventricular ejection fraction was estimated by 2-dimensional echocardiography.nnnRESULTSnNinety-six subjects were enrolled. CHF subjects without IR (CHF/No-IR), but not those with IR (CHF/IR), significantly increased glucose and insulin in response to exercise. Only CHF/No-IR subjects increased FFA in response to exercise (0.14 ± 0.27 mmol/l; p = 0.027). NE increased significantly less with exercise, and CRI was lower in CHF/IR subjects compared with CHF/No-IR subjects (1.3 ± 1.4 vs. 2.5 ± 2.1; 6.4 ± 2.6 vs. 8.5 ± 3.4; p = 0.069). CRI correlated with the exercise-induced increase in FFA (r = 0.41; p < 0.005). These results stayed the same after excluding diabetic patients from the CHF/IR group.nnnCONCLUSIONSnCirculating FFA levels increased during exercise in CHF subjects without IR, but not in those with IR or DM. Increased FFA availability during exercise may represent a catecholamine-dependent compensatory fuel shift in CHF.

Acquired von Willebrand disease during CentriMag support is associated with high prevalence of bleeding during support and after transition to heart replacement therapy.

The Levitronix CentriMag is a magnetically levitated centrifugal-flow pump that can be implanted rapidly in the operating room for both right and left ventricular support. Recently, continuous-flow pumps have been associated with excessive bleeding, which can be at least partially explained by acquired von Willebrand disease (vWD). We investigated whether acquired vWD occurs during CentriMag support and determined the frequency of bleeding complications during device support as well as after transition to long-term support. We found that acquired vWD is common early post CentriMag implantation and is associated with frequent bleeding events and high requirement of blood products.