The Heart and Circulation by Branko Furst

Author:Branko Furst
Language: eng
Format: epub
ISBN: 9783030250621
Publisher: Springer International Publishing

Though not as severe, blunting of the cardiovascular response to patient’s global and regional metabolic requirements also occurs in patients with left ventricular assist devices (LVADs) [96], leading to secondary right ventricular failure in 10–20% of recipients [85] and hepatic dysfunction [97]. Similarly to TAH, the “insensitivity” of pneumatically driven volume displacement VADs to rapid changes (beat-to-beat) in loading conditions of the left, as well as of the right ventricles (RVAD), results in complex baroreceptor and neurohormonal imbalance which can further exacerbate the preexisting heart condition [84, 87]. Over the past decade, the continuous axial flow devices, e.g., HeartMate II and III, have now largely replaced the traditional volume displacement of LVADs as a bridge to transplant and/or recovery as well as destination therapy (Fig. 16.12). These smaller and quieter devices, implanted between the LV apex and the ascending aorta, incorporate electrically driven, or magnetic levitation rotary pump technology. They improve end-organ function, functional capacity, and quality of life of patients awaiting transplantation and are becoming a standard therapeutic option for patients with advanced heart failure, not responding to medical therapy [98]. Significantly, the native heart, even if terminally weak and/or fibrillating, remains intact and the chambers continue to perform the all-important “sensing” function which assures better matching between the flow of blood and the metabolic demands of the tissues.

Fig. 16.12Heartmate II with external control unit and cable connections to battery pack and external control. Continuous axial flow left ventricular assist devices (LVADs) have revolutionized management of patients with advanced heart failure refractory to pharmacological therapy. Part of the blood returning to the left ventricle is drained via the apical port and transferred directly into the ascending aorta (a). Cut-away diagram of the rotor pump (b). The rotor pump flowrate must be adjusted to match the flow into the ventricle to avoid the risk of septal shift and collapse of the ventricle. Like the normal heart, the continuous flow device can eject only the blood it receives. Arrows show direction of blood flow. (Reproduced with permission of St. Jude Medical ©2018)

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