Temporary ventricular assist device support with a catheter-based axial pump: Changing the paradigm at a pediatric heart center.

OBJECTIVE: We report the largest pediatric single-center experience with an Impella (Abiomed Inc) catheter-based axial pump support. METHODS: We conducted a retrospective cohort study of all patients with acute decompensated heart failure or cardiogenic shock requiring catheter-based axial pump support between October 2014 and February 2022. The primary outcome per individual encounter (hospital admission) was defined as bridge-to-recovery, bridge-to-durable ventricular assist device support, bridge-to-cardiac transplantation, or death at 6 months after catheter-based axial pump explantation. Adverse events were defined according to the Pediatric Interagency Registry for Mechanical Circulatory Support criteria. RESULTS: Our final study cohort included 37 encounters with 43 catheter-based axial pump implantations. A single catheter-based axial pump device was used for support in 33 encounters (89%), with 2 catheter-based axial pump devices used in 3 (8%) separate encounters and 3 catheter-based axial pump devices used in 1 (3%) encounter. The median [range] age, weight, and body surface area at implantation were 16.8 [6.9-42.8] years, 61.1 [23.1-123.8] kg, and 1.7 [0.8-2.5] m2, respectively. The predominant causes of circulatory failure were graft failure/rejection in 16 patients (43%), followed by cardiomyopathy in 7 patients (19%), arrhythmia refractory to medical therapies in 6 patients (16%), myocarditis/endocarditis in 4 patients (11%), and heart failure due to congenital heart disease in 4 patients (11%). Competing outcomes analysis showed a positive outcome with bridge-to-recovery in 58%, bridge-to-durable VAD support in 14%, and bridge-to-cardiac transplantation in 14% at 6 months. Fourteen percent of encounters resulted in death at 6 months. CONCLUSIONS: We demonstrate that catheter-based axial pump support in children results in excellent 1- and 6-month survival with an acceptable adverse event profile.

Bivalirudin or Unfractionated Heparin for Anticoagulation in Pediatric Patients on Continuous Flow Ventricular Assist Device Support: Single-Center Retrospective Cohort Study.

OBJECTIVES: Bivalirudin is a direct thrombin inhibitor that is being increasingly used for anticoagulation in children after ventricular assist device (VAD) implantation. While the data on bivalirudin use in pulsatile flow VADs are growing, reports on its use in patients on continuous flow (CF) VAD as well as comparisons of associated outcomes with unfractionated heparin (UFH) remain limited. DESIGN: Retrospective cohort study. SETTING: Single tertiary-quaternary referral center. PATIENTS: All patients less than 21 years old on CF-VAD support who received bivalirudin or UFH for anticoagulation between the years 2016 and 2020. INTERVENTIONS: Not applicable. MEASUREMENTS AND MAIN RESULTS: Clinical characteristics compared between the cohorts included time to target range of anticoagulation, markers of hemolysis, and prevalence of hemocompatibility-related adverse events such as major hemorrhagic complications, ischemic stroke, and pump thrombosis. In 42 unique patients (41 HeartWare HVAD [Medtronic, Minneapolis, MN], one HeartMate 3 LVAD [Abbott Laboratories, Abbott Park, IL]) during the study period, a total of 67 encounters of IV anticoagulation infusions (29 UFH and 38 bivalirudin) were retrospectively reviewed. In comparison with use of UFH, bivalirudin was associated with lesser odds of major bleeding complications (odds ratio [OR], 0.29; 95% CI, 0.09-0.97; p = 0.038). We failed to identify any difference in odds of major thrombotic complications (OR, 2.53; 95% CI, 0.47-13.59; p = 0.450). Eight of the patients (28%) on UFH were switched to bivalirudin due to hemorrhagic or thrombotic complications or inability to achieve therapeutic anticoagulation, while two of the patients (5%) on bivalirudin were switched to UFH due to hemorrhagic complications. Bivalirudin was used for a "washout" in eight cases with concern for pump thrombosis-six had resolution of the pump thrombosis, while two needed pump exchange. CONCLUSIONS: Use of bivalirudin for anticoagulation in patients on CF-VAD support was associated with lesser odds of hemorrhagic complications compared with use of UFH. Bivalirudin "washout" was successful in medical management of six of eight cases of possible pump thrombosis.

Cardiac output and systemic vascular resistance: Clinical assessment compared with a noninvasive objective measurement in children with shock.

PURPOSE: To evaluate physician assessment of cardiac output and systemic vascular resistance in patients with shock compared with an ultrasonic cardiac output monitor (USCOM). To explore potential changes in therapy decisions if USCOM data were available using physician intervention answers. STUDY DESIGN: Double-blinded, prospective, observational study in a tertiary hospital pediatric intensive care unit. Forty children (<18years) admitted with shock, requiring ongoing volume resuscitation or inotropic support. Two to 3 physicians clinically assessed cardiac output and systemic vascular resistance, categorizing them as high, normal, or low. An investigator simultaneously measured cardiac index (CI) and systemic vascular resistance index (SVRI) with USCOM categorized as high, normal, or low. RESULTS: Overall agreement between physician and USCOM for CI (48.5% [κ = 0.18]) and SVRI (45.9% [κ = 0.16]) was poor. Interobserver agreement was also poor for CI (58.7% [κ = 0.33]) and SVRI (52.3% [κ = 0.28]). Comparing theoretical physician interventions to "acceptable" or "unacceptable" clinical interventions, based on USCOM measurement, 56 (21%) physician interventions were found to be "unacceptable." CONCLUSIONS: There is poor agreement between physician-assessed CI and SVRI and USCOM, with significant interobserver variability among physicians. Objective measurement of CI and SVRI may reduce variability and improve diagnostic accuracy.

Validation of an Ultrasound Cardiac Output Monitor as a Bedside Tool for Pediatric Patients.

The aim of our study was to determine the validity of cardiac output (CO) measurements taken with the ultrasonic cardiac output monitor (USCOM) by comparing to CO measured by pulmonary arterial catheter (PAC) thermodilution during cardiac catheterization. We enrolled thirty-one children (<18 years) undergoing cardiac catheterization in this double-blinded, prospective, observational study. The median CO measured by USCOM was 4.37 L/min (IQR 3.73, 5.60 L/min) compared to 4.28 L/min (IQR 3.52, 5.26 L/min) by PAC thermodilution. The bias (mean difference) between the two methods was 0.2 L/min, and the 95% limits of agreement were -1.2 to 1.6 L/min. The mean percentage error of CO between USCOM and PAC thermodilution was 11%. When excluding a sole outlier, the bias between the two measures decreased to 0.1 L/min (95% limits of agreement -0.6 to 0.9 L/min), and the percentage error was reduced to 8%. The median SVRI measured by USCOM was 22.0 Wood Units (IQR 17.0, 26.8 Wood Units) compared to 22.1 Wood Units (IQR 17.6, 27.4 Wood Units) by PAC thermodilution. Bias (mean difference) between the two methods was -0.6 Wood Units, and the 95% limits of agreement were -8.2 to 6.9 Wood Units. We found that the estimation of CO and by extension SVRI with USCOM is reliable against pulmonary artery catheter thermodilution in children with normal cardiac anatomy. Given the noninvasive nature of USCOM, speed of measurement, and relative ease of use, it may be useful as a bedside tool for pediatric patients.