Relevance of Flow Measurement in VADs
VADs (Ventricular Assist Devices) have become a common treatment option for patients with end-stage heart failure and are now used as both bridge-to-transplant and destination therapies. In simple terms, a VAD takes blood from a lower chamber of the heart and helps pump it to the body and vital organs, just as a healthy heart would. To date, over 22,000 VADs have been implanted globally.
As Ventricular Assist Device (VAD) designs continue to evolve, the clinical importance of true volume flow measurement (vs. calculated flow from pump estimations) is becoming more apparent throughout the entire life cycle of the VAD:
Transonic flow technology is commonly used on test racks which monitor VAD performance and provide the Life Cycle Test data required for FDA submissions.
Transonic perivascular measurements are commonly used during VAD implantation procedures to monitor flows and help lower the risk of VAD failure from unseen technical or surgical errors.
Integrating true flow measurements into the device itself allows for early identification of serious complications such as patient arrhythmias, and right heart failure. It can also provide advanced warning to the care team of flow limitation issues such as kinks and circuit blockages, including thrombosis.
Clinical Considerations for Flow Measurement in VADs
Management of acute right heart failure, a common complication following LVAD implantation, requires a reliable estimation of left ventricular preload and contractility. A Transonic® ultrasound Flowprobe on a VAD’s outflow line can provide this information. For example, a progressive decline in outflow accompanied by a loss of pulsatility and/or lower pressure can signal acute right heart failure. But, armed with this knowledge, clinicians can intervene earlier to restore flow.
Thrombosis or clotting within the VAD circuit is a serious complication with a left ventricular assist device. However, with the unmatched accuracy of Transonic H-XL-Series Clamp-on Tubing Sensors, true blood flow through the circuit can be continuously montiored. By comparing actual delivered blood flow to the flow reading on the pump, flow limiting causes can be detected and corrected on the spot.
To Measure is To Know
In VADs, where flow equals life, the accurate measurement of volume flow is an essential quality assurance and safety measure. Transonic’s Transit-time Ultrasound flow measurement (TTFM) is a must have for flow verification and confirmation of pump performance.
Transonic’s miniaturized flow chips allow for the direct integration of a four-crystal sensor over the graft tubing of the VAD itself. When integrated into the alert system of the device, the flow measurement can offer forewarning for life-threatening problems, and, depending on set-up, can even call the patient in for preemptive treatment. An external clamp-on Flowsensor clips onto the tubing to continuously monitor actual flow delivery to the patient. Measurements are non-invasive, continuous and bi-directional.
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