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Use of Two Intracorporeal Ventricular Assist Devices As a Total Artificial Heart
Published on: May 11, 2018
Pathologic analysis of 34 explanted symbion ventricular assist devices and 10 explanted Jarvik-7 total artificial
1Department of Pathology, Brigham and Women's Hospital, and Harvard Medical School, Boston, Massachusetts, USA.
Insights
Thrombus formation is a major complication in Symbion ventricular assist devices and Jarvik-7 total artificial hearts. Pathological analysis revealed thrombi in most devices, primarily on valves and diaphragms, with minimal impact on function.
Area of Science:
- Cardiovascular Engineering
- Biomaterials Science
- Pathology
Background:
- Ventricular assist devices (VADs) and total artificial hearts (TAHs) are critical for end-stage heart failure treatment.
- Thrombus formation remains a significant challenge, impacting device longevity and patient outcomes.
- Understanding device-specific pathological findings is crucial for improving future designs.
Purpose of the Study:
- To conduct a detailed pathological analysis of explanted Symbion VADs and Jarvik-7 TAHs.
- To identify and characterize thrombus formation sites and prevalence.
- To correlate pathological findings with device design features for potential redesign.
Main Methods:
- Pathological analysis of 34 Symbion VADs and 10 Jarvik-7 TAHs used clinically.
- Quantitative analysis of thrombus distribution using polar coordinate mapping for diaphragmatic thrombi.
- Assessment for infection and mechanical defects.
Main Results:
- Thrombus formation observed in 85% of VADs and 75% of TAHs, with small thrombi generally not affecting function.
- Major thrombus sites included valves, connections, diaphragms (VADs), and paravalvular areas (TAHs).
- Specific areas on the diaphragm were identified as highly susceptible to thrombus formation.
Conclusions:
- Thrombus formation on valves, connectors, and diaphragms is the primary complication associated with Symbion VADs and Jarvik-7 TAHs.
- Findings highlight specific design features requiring modification to mitigate thrombus risk.
- Infections and mechanical defects were infrequent in this cohort.
Abstract:
Thirty-four Symbion ventricular assist devices and 10 Jarvik-7 total artificial hearts that had been in clinical use for 1 to 164 days (assist devices) and 1 to 176 days (artificial hearts) were analyzed using a detailed protocol for pathological analysis. The major finding was thrombus formation in 85% of the assist devices and 75% of the artificial hearts. Thrombi were generally small and in only one case interfered with pump function. The number of distinct thrombi per device was 2.5 mean (range 0-5) for assist devices and 2.6 mean (range 0-6) for artificial hearts. Major sites of thrombus formation in the assist devices were valves, valve connections, diaphragm, and the inner surface of the deairing port. Artificial heart thrombi were predominantly paravalvular. In order to relate sites of diaphragmatic thrombi to specific design features of the assist device, the pattern was analyzed quantitatively using a polar coordinate mapping technique to measure the average radial thrombus length around the circumference of each diaphragm. The concentration of thrombus was highest between the valve orifices and lateral to the outflow valve. This identified areas particularly susceptible to thrombus formation and thereby targets specific pump features for redesign. Intraluminal infection was seen in 1 assist device and 1 artificial heart (outflow grafts); extraluminal infection was seen in two artificial hearts (infected hematomas around the outflow grafts). Neither device mineralization for mechanical defects were noted. Thus thrombus formation related to (and potential thromboemboli from) valves, their connectors, and the pumping diaphragms represents the major device-associated complication of pneumatic Symbion assist devices and Jarvik-7 artificial hearts. Thrombi associated with other sites and both intra- and extraluminal infection occur less frequently.
