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result(s) for
"Mahr, Claudius"
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In Vitro Investigation of the Effect of Left Ventricular Assist Device Speed and Pulsatility Mode on Intraventricular Hemodynamics
by
Li, Song
,
Beckman, Jennifer A
,
Miramontes Marissa
in
Flow distribution
,
Flow resistance
,
Flow velocity
2021
Stroke has become the main cause of mortality and morbidity in patients treated with Left Ventricular Assist Devices (LVADs). The hemodynamics of the left ventricle are altered by the implantation of an LVAD, with the increase of thrombogenic flow patterns, such as stagnation regions. Time-resolved stereo particle image velocimetry (Stereo-PIV) measurements of the flow inside a patient-specific model of the left ventricle (LV) implanted with an LVAD were performed. The effects of LVAD speed, peripheral resistance and afterload were investigated. The impact of activating the LVAD pulsatility mode (periodic speed modulation) was also evaluated. Analysis of the velocity measurements in two orthogonal planes revealed stagnation zones which may be favorable to thrombus formation. Increasing LVAD speed, despite increasing the flow rate through the inflow cannula, does not automatically result in smaller stagnation regions. These results demonstrated the strong interdependence of peripheral resistance, afterload and flow through the LVAD. As a consequence, the pulsatility mode showed very limited effect on overall flow rate. However, it did reduce the size of high stagnation areas. This study showed how LVAD speed, peripheral resistance and afterload impact the complex intraventricular flow patterns in a ventricle implanted with an LVAD and quantify their thrombogenic risk.
Journal Article
Feasibility of Very Early Identification of Cardiogenic Shock by Semi-automated Ultrasound Exam in the Emergency Department
by
Morales, Gabriel
,
McCabe, James
,
Mahr, Claudius
in
Artificial intelligence
,
Automation
,
Blood pressure
2022
BackgroundCardiogenic shock (CS) is critical end-organ hypoperfusion due to reduced cardiac output. Early therapy, such as vasoactive agents or the initiation of mechanical circulatory support (MCS), requires early diagnosis and is associated with better outcomes. A novel ultrasound platform (GE Healthcare, Milwaukee, WI) has semi-automated imaging software (SAIS), which could simplify the point-of-care ultrasound (POCUS) diagnosis of CS. We assessed the feasibility of using POCUS with SAIS in patients in shock, determined the ability of SAIS to identify the subset of patients with CS, and described the process and outcome of care of patients with vs. without CS after presenting to Emergency Department (ED) with hypotension.MethodsThis prospective case-control study was conducted at an urban ED. Physicians with prior POCUS education received one hour of training with the study device. The qualitative ejection fraction was determined by visual assessment. SAIS measurements of hemodynamics were made with the study device and included left ventricle outflow tract velocity time integral (LVOT VTI), inferior vena cava collapsibility or distensibility indices, and pulmonary B-line assessment. ED patients with a systolic blood pressure ≤ 90 mmHg or need for a vasopressor initiation in the ED were enrolled. The diagnosis of CS was determined by a medical record review. All data were summarized descriptively.ResultsTwenty-nine cases underwent POCUS, and 87 controls did not. Baseline characteristics, process, and outcome of care were similar between groups. Seventy-nine percent (79%) of cases had a complete POCUS with SAIS. Of these, 55% had reduced LVOT VTI, 38% had IVC collapsibility <50%, and 48% of cases had a B-line pattern consistent with pulmonary edema. The mean LVOT VTI for cases with CS was 9.4± 5.4 cm; the mean LVOT VTI for cases without CS was 15.2 ± 6.0 cm. Among patients who did not undergo POCUS, 31 (36%) had a formal echocardiogram, and eight (9%) had a final diagnosis of cardiogenic shock during hospitalization.ConclusionPhysicians with one hour of platform-specific training were able to implement POCUS with SAIS among patients who present with shock. POCUS with SAIS may aid in the early recognition of CS.
Journal Article
A Peek at LVADs Pumping to Recovery
by
Mahr, Claudius
,
Arshad, Samiullah
,
Vaidya, Gaurang N
in
Heart surgery
,
Medical equipment
,
Recovery (Medical)
2022
Left ventricular assist devices (LVADs) have revolutionized the management of patients with advanced heart failure refractory to medical therapy. Current indications of LVADs include Bridge to Transplantation (BTT), Destination Therapy (DT) for long-term use, Bridge to the Decision (BTD) used as a temporary measure, and lastly Bridge to Recovery (BTR). Here, we briefly review the clinical evidence and the molecular mechanisms behind myocardial recovery following LVAD placement. We also share institutional protocols used at 2 major medical centers in the USA.
Journal Article
Discordance between aPTT and anti‐Xa in monitoring heparin anticoagulation in mechanical circulatory support
by
Li, Song
,
Mahr, Claudius
,
Sabath, Daniel E.
in
Aged
,
Anticoagulants
,
Anticoagulants - administration & dosage
2024
Aims It is unclear whether activated partial thromboplastin time (aPTT) or anti‐Xa is more accurate for monitoring heparin anticoagulation in mechanical circulatory support (MCS) patients. This study investigates the relationship between aPTT and anti‐Xa in MCS patients and identifies predictors of discordance. Methods and results aPTT and anti‐Xa were simultaneously measured in a prospective cohort of MCS patients receiving unfractionated heparin at a tertiary academic medical centre. Therapeutic aPTT and anti‐Xa levels were 60–100 s and 0.3–0.7 IU/mL, respectively, and concordance was defined as both levels being subtherapeutic, therapeutic, or supratherapeutic. To identify predictors of discordance, both a machine learning random forest model and a multivariate regression model were applied to patient demographics, device type, and 14 laboratory variables; 23 001 pairs of simultaneously measured aPTT/anti‐Xa were collected from 699 MCS patients. aPTT and anti‐Xa were concordant in 35.5% of paired observations and discordant in 64.5% (aPTT > antiXa 61.5%; aPTT < antiXa 3.0%). Discordance with a high aPTT relative to anti‐Xa (aPTT > antiXa) was associated with high INR, eGFR, and total bilirubin, as well as low platelets, haemoglobin, pre‐albumin, white blood cell count, and haptoglobin. Total artificial heart and durable ventricular assist devices were more likely to be associated with aPTT > anti‐Xa than temporary MCS devices. Conclusions aPTT and anti‐Xa were frequently discordant in MCS patients receiving heparin anticoagulation. Clinical conditions common in MCS patients such as concurrent warfarin use, malnutrition, haemolysis, and thrombocytopenia, as well as durable type of MCS devices were associated with a high aPTT relative to anti‐Xa.
Journal Article
Heart Transplantation Outcomes with Donation After Circulatory Death in Patients with Left Ventricular Assist Device
2025
Abstract
Aims
Donation after circulatory death (DCD) has emerged as a strategy to increase the donor pool for heart transplantation (HT). Left ventricular assist device (LVAD) patients represent a discrete and unique population. We sought to explore the early outcomes of DCD-HT compared with donation after brain death (DBD) HT in LVAD patients.
Methods and results
We obtained data from the United Network of Organ Sharing database. The main cohort consisted of adults listed for HT between 17 October 2018 and 3 July 2024, with LVAD implanted before or after listing. The primary outcome was survival within the first year post-HT. There were 3336 patients with LVAD underwent HT during the study period (median age 55 years (interquartile range 45–62), 24% women, 29% Black, 89% DBD). The short-term post-HT mortality in LVAD patients who underwent DCD HT was not significantly different from DBD (adjusted hazard ratio [aHR] 1.00, 95% CI 0.70–1.42, P value > 0.9). The likelihood of transplantation within 1 year was higher at centres performing DCD (aHR 1.44, 95% CI 1.39–1.49, P < 0.001). Despite the longer donor-recipient distance in DCD-HT, in-hospital outcomes (stroke and acute kidney injury requiring dialysis) were not different from DBD-HT. A higher incidence of primary graft dysfunction (adjusted risk ratio [aRR] 3.8, 95% CI 2.5–5.7, P < 0.001), and treated rejection was observed with DCD-HT (aRR 1.48, 95% CI 1.14–1.93, P = 0.003).
Conclusions
In LVAD patients who received DCD HT, early post-transplant survival, stroke, acute kidney injury and length of stay were not significantly different from those who underwent DBD HT. There were increased rates of primary graft dysfunction and treated rejection among LVAD patients who underwent DCD HT. Patients in a DCD centre were significantly more likely to be transplanted earlier.
Journal Article
Evaluating ventricular assist device outcomes internationally with a focus on neurological events
2019
[...]there were no significant differences in survival or adverse event rates (stroke) between the HeartMate II and HVAD devices. [...]even though patient inclusion is mandatory, the registry is not comprehensive and hence analysis lacks information on many key types of adverse events and treatment metrics. According to the INTERMACS registry, the overall rate of LVAD implantation in the USA is increasing, and despite destination therapy growing as a share of all LVAD implantations, the absolute number of both BTT and DT LVAD implantations per year is rising.2 In the context of near static heart transplant rates, the median waiting time to transplantation and the percentage of LVAD patients on the wait list has steadily increased since 2006.3 In addition, the new United Network for Organ Sharing heart allocation system coming into effect this fall aims to further stratify the risk of LVAD patients by lowering the relative priority of stable LVAD outpatients (https://optn.transplant.hrsa.gov/media/2414/adult_heart_infographic.pdf).4 Thus, the overall transplant rate of the BTT LVAD population in the USA may trend towards the UK rate, making the UK BTT LVAD experience especially relevant. BTT, bright to transplant; ENDURANCE, A Prospective, Randomised, Controlled, Un-blinded, Multi-Centre Clinical Trial to Evaluate the HeartWare Ventricular Assist System for Destination Therapy of Advanced Heart Failure;HM3, HeartMate III; INTERMACS, Interagency Registry for Mechanically Assisted Circulatory Support; MOMENTUM 3, Multicentre Study of MagLev Technology in Patients Undergoing MCS Therapy With HeartMate 3; TIA, transient ischaemic attack The good news is that we now have evidence that better medical therapy, in this case intensive blood pressure control, can reduce stroke risk.
Journal Article
Cost‐effectiveness of left ventricular assist devices as destination therapy in the United Kingdom
by
Cheng, Richard K.
,
Ismyrloglou, Eleni
,
Mahr, Claudius
in
Blood clots
,
Cost analysis
,
Cost‐effectiveness
2021
Aims Continuous‐flow left ventricular assist devices (LVADs) as destination therapy (DT) are a recommended treatment by National Institute for Health and Care Excellence England for end‐stage heart failure patients ineligible for cardiac transplantation. Despite the fact that DT is frequently used as an LVAD indication across other major European countries and the United States, with consistent improvements in quality‐of‐life and longevity, National Health Service (NHS) England does not currently fund DT, mainly due to concerns over cost‐effectiveness. On the basis of the recently published ENDURANCE Supplemental Trial studying DT patients, we assessed for the first time the cost‐effectiveness of DT LVADs compared with medical management (MM) in the NHS England. Methods and results We developed a Markov multiple‐state economic model using NHS cost data. LVAD survival and adverse event rates were derived from the ENDURANCE Supplemental Trial. MM survival was based on Seattle Heart Failure Model estimates in the absence of contemporary clinical trials for this population. Incremental cost‐effectiveness ratios (ICERs) were calculated over a lifetime horizon. A discount rate of 3.5% per year was applied to costs and benefits. Deterministic ICER was £46 207 per quality‐adjusted life year (QALY). Costs and utilities were £204 022 and 3.27 QALYs for the LVAD arm vs. £77 790 and 0.54 QALYs for the MM arm. Sensitivity analyses confirmed robustness of the primary analysis. Conclusions The implantation of the HeartWare™ HVAD™ System in patients ineligible for cardiac transplantation as DT is a cost‐effective therapy in the NHS England healthcare system under the end‐of‐life willingness‐to‐pay threshold of £50 000/QALY, which applies for VAD patients.
Journal Article
Outcome differences in acute vs. acute on chronic heart failure and cardiogenic shock
by
Mahr, Claudius
,
McCabe, James M.
,
Nguyen, Vidang
in
Acute coronary syndromes
,
Blood pressure
,
Cardiac arrhythmia
2020
Aims Despite advances in coronary reperfusion and percutaneous mechanical circulatory support, mortality among patients presenting with cardiogenic shock (CS) remains unacceptably high. Clinical trials and risk stratification tools have largely focused on acute CS, particularly secondary to acute coronary syndrome. Considerably less is understood about CS in the setting of acute decompensation in patients with chronic heart failure (HF). We sought to compare outcomes between patients with acute CS and patients with acute on chronic decompensated HF presenting with laboratory and haemodynamic features consistent with CS. Methods and results Sequential patients admitted with CS at a single quaternary centre between January 2014 and August 2017 were identified. Acute on chronic CS was defined by having a prior diagnosis of HF. Initial haemodynamic and laboratory data were collected for analysis. The primary outcome was in‐hospital mortality. Secondary outcomes were use of temporary mechanical circulatory support, durable ventricular assist device implantation, total artificial heart implantation, or heart transplantation. Comparison of continuous variables was performed using Student's t‐test. For categorical variables, the χ2 statistic was used. A total of 235 patients were identified: 51 patients (32.8%) had acute CS, and 184 patients (64.3%) had acute decompensation of chronic HF with no differences in age (52 ± 22 vs. 55 ± 14 years, P = 0.28) or gender (26% vs. 23%, P = 0.75) between the two groups. Patients with acute CS were more likely to suffer in‐hospital death (31.4% vs. 9.8%, P < 0.01) despite higher usage of temporary mechanical circulatory support (52% vs. 25%, P < 0.01) compared with patients presenting with acute on chronic HF. The only clinically significant haemodynamic differences at admission were a higher heart rate (101 ± 29 vs. 82 ± 17 b.p.m., P < 0.01) and wider pulse pressure (34 ± 19 vs. 29 ± 10 mmHg, P < 0.01) in the acute CS group. There were no significant differences in degree of shock based on commonly used CS parameters including mean arterial pressure (72 ± 12 vs. 74 ± 10 mmHg, P = 0.23), cardiac output (3.9 ± 1.2 vs. 3.8 ± 1.2 L/min, P = 0.70), or cardiac power index (0.32 ± 0.09 vs. 0.30 ± 0.09 W/m2, P = 0.24) between the two groups. Conclusions Current definitions and risk stratification models for CS based on clinical trials performed in the setting of acute coronary syndrome may not accurately reflect CS in patients with acute on chronic HF. Further investigation into CS in patients with acute on chronic HF is warranted.
Journal Article
Accuracy of Doppler blood pressure measurement in HeartMate 3 ventricular assist device patients
2020
Aims Optimal blood pressure (BP) control is imperative to reduce complications, especially strokes, in continuous flow ventricular assist device (VAD) patients. Doppler BP has been shown to be an accurate and reliable non‐invasive BP measurement method in HeartMate II and HVAD patients. We examined whether Doppler BP is also accurate in patients with the HeartMate 3 VAD. Methods and results In a prospective, longitudinal cohort of HeartMate 3 patients, arterial line BP and simultaneously measured Doppler opening pressure were obtained. Correlation and agreement between Doppler opening pressure and arterial line mean arterial pressure (MAP) versus systolic blood pressure (SBP) were analysed, as well as the effect of pulse pressure on the accuracy of Doppler opening pressure. A total of 589 pairs of simultaneous Doppler opening pressure and arterial line pressure readings were obtained in 43 patients. Doppler opening pressure had good correlation with intra‐arterial MAP (r = 0.754) and more closely approximated MAP than SBP (mean error 2.0 vs. −8.6 mmHg). Pulse pressure did not have a clinically significant impact on the accuracy of the Doppler BP method. These results in HeartMate 3 patients are very similar to previous results in HeartMate II and HVAD patients. Conclusions Doppler BP method should be the default non‐invasive BP measurement method in continuous flow VAD patients including patients implanted with the HeartMate 3.
Journal Article
Accuracy of Doppler Blood Pressure Measurement in Continuous-Flow Left Ventricular Assist Device Patients
2019
Abstract
Aims
Accurate blood pressure (BP) measurement in continuous-flow ventricular assist device (CF-VAD) patients is imperative to reduce stroke risk. This study assesses the accuracy of the Doppler opening pressure method compared with the gold standard arterial line method in CF-VAD patients.
Methods and results
In a longitudinal cohort of HeartMate II and HVAD patients, arterial line BP and simultaneously measured Doppler opening pressure were obtained. Overall correlation, agreement between Doppler opening pressure and arterial line mean vs. systolic pressure, and the effect of arterial pulsatility on the accuracy of Doppler opening pressure were analysed. A total of 1933 pairs of Doppler opening pressure and arterial line pressure readings within 1 min of each other were identified in 154 patients (20% women, mean age 55 ± 15, 50% HeartMate II and 50% HVAD). Doppler opening pressure had good correlation with invasive mean arterial pressure (r = 0.742, P < 0.0001) and more closely approximated mean than systolic BP (mean error 2.4 vs. −8.4 mmHg). Arterial pulsatility did not have a clinically significant effect on the accuracy of the Doppler opening pressure method.
Conclusions
Doppler opening pressure should be the standard non-invasive method of BP measurement in CF-VAD patients.
Journal Article