William Hallinan

Does the need for noncardiac surgery during ventricular assist device therapy impact clinical outcome

BACKGROUND The role of the ventricular assist device (VAD) in the management of heart failure is expanding. Despite its success, the clinical course for patients requiring noncardiac surgery (NCS) during VAD support is not well described. The objective of this study was to identify VAD patients requiring NCS (+NCS) and compare outcomes with those not requiring NCS (-NCS). METHODS Patients undergoing VAD implant from 2000 to 2007 were reviewed. NCS procedures, survival, and complications were collected. Survival at 1 year from implant, overall survival at the study conclusion, survival time from implant, and outcome of VAD therapy were compared between groups. RESULTS We enrolled 142 subjects. Demographics did not differ between groups. Twenty-five subjects (18%) underwent 27 NCS procedures. Perioperative survival was 100% and 28-day survival was 64%. Survival to discharge was 56%. Bleeding occurred in 48%. Infection occurred in 33%. Estimated blood loss was 355 mL, and the international normalized ratio at time of NCS was 1.9. Laparoscopy was performed in 3 cases. There was no difference in 1-year survival (59% vs 54%), survival at study conclusion (44% vs 46%) or survival time (517 vs 523 days) between +NCS subjects and -NCS subjects. There were similar causes of death in both groups. The +NCS group was on VAD support longer (245 vs 87 days; P < .01), and less likely to undergo heart transplantation (12% vs 35%; P < .01). CONCLUSION NCS is not uncommon during VAD therapy. Bleeding and infection were common complications. Despite this, NCS seems to be feasible and safe and does not seem to increase mortality in the VAD population.

Evaluation and treatment of pump thrombosis and hemolysis

Ventricular assist devices (VADs) are not fully biocompatible, and are therefore predisposed to device thrombosis and subsequent pump dysfunction. Clinically significant hemolysis in VADs most often occurs as a result of device thrombosis, but can also be caused by other factors. Herein we describe the evaluation and management of VAD thrombosis and hemolysis.

Clinical predictors of survival in patients treated with therapeutic hypothermia following cardiac arrest

INTRODUCTION Therapeutic hypothermia has been shown to provide neuroprotection and improved survival in patients suffering a cardiac arrest. We report outcomes of consecutive patients receiving therapeutic hypothermia for cardiac arrest and describe predictors of short and long-term survival. METHODS Eighty patients receiving therapeutic hypothermia between January 2005 and December 2008 were identified and categorized as those who survived and died. Outcomes and predictors of survival were determined. RESULTS Forty-five patients (56%) survived to hospital discharge and were alive at 30 days and among survivors 41 (91%) were alive 1 year after discharge. Survivors were younger, were more likely to present with VF, required less epinephrine during resuscitation, were more likely to have preserved renal function, and were less likely to be taking beta-blockers and ACE inhibitors. Predictors of survival included VF on presentation (OR 14.9, CI 2.7-83.2, p=0.002), pre-cardiac arrest aspirin use (OR 9.7, CI 1.6-61.1, p=0.02), return of spontaneous circulation <20 min (OR 9.4, CI 2.2-41.1, p=0.003), absence of coronary artery disease (OR 5.3, CI 1.1-24.7, p=0.002) and preserved renal function. CONCLUSION Therapeutic hypothermia is useful in the treatment of patients suffering a cardiac arrest. Several clinical factors may aid in predicting patients who are likely to survive after a cardiac arrest.

Not all prehospital time is equal: Influence of scene time on mortality.

BACKGROUND Trauma is time sensitive, and minimizing prehospital (PH) time is appealing. However, most studies have not linked increasing PH time with worse outcomes because raw PH times are highly variable. It is unclear whether specific PH time patterns affect outcomes. Our objective was to evaluate the association of PH time interval distribution with mortality. METHODS Patients transported by emergency medical services in the Pennsylvania trauma registry from 2000 to 2013 with a total PH time (TPT) of 20 minutes or longer were included. TPT was divided into three PH time intervals: response, scene, and transport time. The number of minutes in each PH time interval was divided by TPT to determine the relative proportion each interval contributed to TPT. A prolonged interval was defined as any one PH interval contributing equal to or greater than 50% of TPT. Patients were classified by prolonged PH interval or no prolonged PH interval (all intervals < 50% of TPT). Patients were matched for TPT, and conditional logistic regression determined the association of mortality with PH time pattern, controlling for confounders. PH interventions were explored as potential mediators, and PH triage criteria used identify patients with time-sensitive injuries. RESULTS There were 164,471 patients included. Patients with prolonged scene time had increased odds of mortality (odds ratio, 1.21; 95% confidence interval, 1.02–1.44; p = 0.03). Prolonged response, transport, and no prolonged interval were not associated with mortality. When adjusting for mediators including extrication and PH intubation, prolonged scene time was no longer associated with mortality (odds ratio, 1.06; 95% confidence interval, 0.90–1.25; p = 0.50). Together, these factors mediated 61% of the effect between prolonged scene time and mortality. Mortality remained associated with prolonged scene time in patients with hypotension, penetrating injury, and flail chest. CONCLUSION Prolonged scene time is associated with increased mortality. PH interventions partially mediate this association. Further study should evaluate whether these interventions drive increased mortality because they prolong scene time or by another mechanism, as reducing scene time may be a target for intervention. LEVEL OF EVIDENCE Prognostic/epidemiologic study, level III.

Non-invasive flow measurement of a rotary pump ventricular assist device using quantitative contrast echocardiography.

BACKGROUND Many implantable ventricular assist devices (VADs) have no direct measurement of pump output. The aim of this study was to test the hypothesis that quantitative contrast echocardiography can be used to measure VAD output. METHODS Contrast-enhanced Doppler velocity-time integral (VTI) was measured in the VAD inlet and outlet cannulae. Doppler flow (Doppler Q=Doppler VTIxcannula area) was compared with measured flow (Q). A total of 130 flow measurements were made (at 6400 and 12,000 rpm). RESULTS Doppler Q in the outflow and inflow cannulae showed an excellent correlation with measured Q (outlet Doppler Q=1.0052 xQ+0.048, R2=0.9865; inlet Doppler Q=1.5043 xQ+0.003, R2=0.9904), but inlet Doppler Q was 50% higher. Correcting for the flow profile of the conical inlet tube yielded excellent correlation (inlet Doppler Q=1.0029 xQ+0.002, R2=0.9904). CONCLUSION Noninvasive Doppler flow techniques can be used to accurately measure VAD flow, but the flow profile in the cannula needs to be taken into account.

Predictors and clinical relevance of ventricular tachyarrhythmias in ambulatory patients with a continuous flow left ventricular assist device

BACKGROUND Patients with a left ventricular assist device (LVAD) are at high risk for ventricular tachyarrhythmias (VTAs). OBJECTIVE We aimed to identify clinical predictors of VTAs and subsequent outcomes after VTA in ambulatory LVAD patients. METHODS A retrospective study of 149 patients with a continuous flow HeartMate II LVAD who survived to discharge from index hospitalization after LVAD implantation was performed from January 10, 2005, to September 3, 2013. A multivariate Cox model was used to assess clinical predictors of VTAs. RESULTS During a mean follow-up period of 2.1 ± 1.2 years, 41 patients (28%) experienced VTAs; 30 of these patients (71%) had ventricular tachycardia, and 11 (29%) had ventricular fibrillation. History of VTAs before LVAD (hazard ratio [HR] 3.06; 95% confidence interval [CI] 1.57-5.96; P = .001) and history of atrial fibrillation (AF) (HR 3.13; 95% CI 1.60-6.11; P = .008) were the most powerful predictors of VTAs after LVAD implantation. There were 19 deaths (46%) among patients with VTAs and 15 deaths (14%) among patients without VTAs (P < .001). In multivariate analysis, time-dependent VTAs after LVAD implantation were associated with a significantly higher risk of all-cause mortality when compared with those without VTAs (HR 7.28; 95% CI 3.50-15.15; P < .001). CONCLUSION In ambulatory LVAD patients, history of VTAs before LVAD implantation and history of AF predict VTAs after LVAD implantation. VTAs are associated with an increased risk of mortality. In such patients, aggressive measures to control VTAs and AF should be considered.

Long-term total cardiac support in a Fontan-type circulation with HeartMate II left ventricular assist device

Interest in utilizing long-term mechanical circulatory support for Fontan-type circulation has been high. Unfortunately, so far such attempts have not been successful. Herein, we are presenting the first case of an individual with biventricular heart failure and Fontan-type circulation on long-term mechanical circulatory support with a continuous-flow left ventricular assist device.

Reduce Driveline Trauma Through Stabilization and Exit Site Management: 30 Days Feasibility Results from the Multicenter RESIST Study.

The percutaneous lead management kit (PLMK) was developed for the HeartMate 2 (HM2) left ventricular assist device (LVAD) to reduce trauma at the exit site and to maintain a clean environment. REduce Driveline Trauma through StabIlization and Exit Site ManagemenT (RESIST) was a multicenter, prospective, nonrandomized study designed to evaluate the feasibility of the PLMK for managing the HM2 driveline exit site. Fifty patients were enrolled at five sites at a median of 495 days post-HM2 implant; 92% (46 of 50) of patients used the PLMK for a minimum of 30 days. At 30 days, more patients found the PLMK to be extremely comfortable (80% vs. 37%, p < 0.001) and extremely effective at stabilizing the driveline (82% vs. 40%, p < 0.001) compared with each center’s standard of care. Frequency of dressing changes was 6–7 days or higher for 85% of the patients with PLMK. Three patients developed driveline infection while on PLMK (6%, 0.15 events per patient year), and 35 patients continued to use the PLMK after 6 months. The PLMK is easy to use, increases patient comfort, and increases driveline stability with a dressing change frequency of 6–7 days.

Single‐Center Experience With HeartMate II Left Ventricular Assist Device Explantation

In patients with continuous flow left ventricular assist devices (CF-LVADs) myocardial recovery is uncommon. Given the heterogeneity of the population implanted and low incidence of recovery, the discovery of native left ventricular (LV) recovery and criteria for explantation of CF-LVAD system is not clearly determined. We sought to analyze the characteristics of the patients who underwent CF-LVAD explantation at our institution. Prospectively collected data on patients supported with CF-LVADs were reviewed retrospectively. Patients who underwent CF-LVAD explants were identified and their characteristics were analyzed with a focus on patient presentation and determinants of explantability. From November 2006 to June 2014, 223 patients (181 male, 42 female) underwent implantation of HeartMate II LVAD. Seven female (16.7%) and one male (0.6%) patients were explanted (P < 0.001). Mean age was 43 ± 9 years and etiology for cardiomyopathy was ischemic in three (37.5%) patients, nonischemic in four (50%) patients, and mixed in the one (12.5%) male patient of the cohort. Five (62.5%) patients presented acutely with significant hemolysis, and were found to have LV improvement as well as reduced, absent, or reversed diastolic flow velocities on echocardiography. Overall, mean lactate dehydrogenase level before explantation was 1709 ± 1168 U/L compared to the mean baseline level of 601 ± 316 U/L (P = 0.048). Mean LV ejection fraction (LVEF) improved from 17 ± 7% preimplant to 56 ± 11% pre-explantation (P < 0.001). Median number of days on CF-LVAD support was 870 (interquartile range, 209-975) while mean duration of follow-up after the CF-LVAD explantation was 276 ± 240 days. Mean LVEF dropped from 46 ± 19% postexplantation to 34 ± 10% during the most recent follow-up (P = 0.015). At our institution, patients who underwent LVAD explants were predominantly women with nonischemic cardiomyopathy. Clinical evidence of hemolysis and echocardiographic evidence of reduced or absent diastolic flow velocities were common findings in these patients. Over time, patients native LV function declined in the absence of LVAD (after LVAD explantation). Significant challenges remain in predicting LV recovery and identifying those individuals who have recovered myocardial function significant enough to be explanted.

Evolving strategies in the treatment of acute myocardial infarction-induced cardiogenic shock

Despite advances in medical technology and re-vascularization interventions, the mortality rate for cardiogenic shock (CS) following acute myocardial infarction has remained at 50%. The majority of these mortalities are from left ventricular failure resulting in multi-system organ dysfunction. The field of mechanical circulatory support (MCS) has evolved within the past decade, with improved outcomes from extracorporeal membrane oxygenation as well as continuous-flow left ventricular assist devices (CF LVADs). In this paper, we discuss our institutional treatment strategies, the rationale for the protocol development, and our improved outcomes when using MCS in patients with refractory CS following acute myocardial infarction.