Key result
Intraoperative direct LVAD flow measurement with an ultrasonic flow probe yielded significantly higher flow values (mean difference 0.56 L/min at 4400 rpm; P<0.001) compared to device-estimated flow.
Why the study?
Does intraoperative direct LVAD flow measurement using an ultrasonic flow probe differ from algorithmic flow estimations in patients undergoing durable LVAD implantation?
Observational (n=20)
No
Does intraoperative direct LVAD flow measurement using an ultrasonic flow probe differ from algorithmic flow estimations in patients undergoing durable LVAD implantation?
Intraoperative direct LVAD flow measurement using an ultrasonic flow probe yields significantly higher flow values (by approximately 0.5 L/min) compared to the device's algorithmic estimation across various speed settings.
Answers are grounded in this paper and cite their sources.
Urges caution interpreting device-estimated LVAD flow intraoperatively; leaves open optimal monitoring strategy pending larger confirmatory studies.
INTRODUCTION: Left ventricular assist devices (LVAD) have become an established therapy for end-stage heart failure over the last three decades. In currently available devices, the blood flow is estimated using a power consumption algorithm. In this study, intraoperative direct LVAD flow measurement with an ultrasonic flow probe was analyzed. METHODS: As part of our routine evaluation of optimal LVAD flow, intraoperative direct flow measurement at the outflow graft was performed using a 14-mm ultrasonic flow probe. Direct LVAD flow measurements were performed at different speed levels: 4400 rpm, 4800 rpm, 5200 rpm, and the optimal flow setting before chest closure. In twenty consecutive patients who underwent a durable LVAD implantation via median sternotomy in our institution between January and April 2025, direct flow measurement was compared with the estimated flow provided by the device. RESULTS: Median age was 63 [60;68] years, 17 (85%) were male, 8 (40%) had a history of acute myocardial infarction. Temporary mechanical circulatory support with a microaxial flow pump was necessary in 8 (40%) patients prior to durable LVAD implantation. Destination therapy was indicated in 12 (60%) cases. Mean flows at 4400 rpm were 2.9 ± 0.3 and 3.4 ± 0.4 L/min calculated by the pump and measured by the probe, respectively. Mean difference between the measurements was 0.56 L/min (95% CI [0.40, 0.70], p < 0.001). Mean flows at 4800 rpm were 3.5 ± 0.3 and 4.1 ± 0.5 L/min, respectively. Mean difference between the measurements was 0.55 L/min (95% CI [0.33, 0.77], p < 0.001). Mean flows at 5200 rpm were 4.2 ± 0.3 and 4.7 ± 0.5 L/min, respectively. Mean difference between the measurements was 0.53 L/min (95% CI [0.40, 0.70], p = 0.001). Mean optimal speed for patients was 5400 rpm, mean difference between the measurements was 0.49 L/min (95% CI [0.23, 0.74], p = 0.001). CONCLUSION: LVAD flow measured with an ultrasonic flow probe shows significantly higher results (approximately +0.5 L/min) compared to the flow estimated by the device. The difference remains constant at different LVAD speed modes. Intraoperative flow measurement employing an ultrasonic flow probe is a valuable tool for hemodynamic evaluation during implantation of a durable LVAD.
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Nersesian et al. (2026) conducted an observational in End-stage heart failure (n=20). Intraoperative direct LVAD flow measurement with an ultrasonic flow probe vs. Estimated flow provided by the device was evaluated on Flow measurement at 4400 rpm (MD 0.56 L/min, 95% CI 0.40, 0.70, p=< 0.001). Intraoperative direct LVAD flow measurement with an ultrasonic flow probe yielded significantly higher flow values (mean difference 0.56 L/min at 4400 rpm; P<0.001) compared to device-estimated flow.
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