title: Coronary vascular resistance increases under full bypass support of centrifugal pumps--relation between myocardial perfusion and ventricular workload during pump support.
abstract: Coronary circulation is closely linked to myocardial oxygen consumption (MVO(2)), and previous reports have suggested decreased coronary flow (CoF) under left ventricular assist device support. Decreased CoF itself under support is not unfavorable because the native heart can be well unloaded and myocardial oxygen demand is also decreased. There should be an autoregulatory system that would maintain optimal CoF according to oxygen demand; however, the detailed mechanism is still unclear. The aim of the current study is to evaluate the effect of centrifugal pumps on CoF under varied bypass rates in relation to left ventricle workload. A centrifugal pump, EVAHEART (Sun Medical Technology Research Corporation, Nagano, Japan), was installed in an adult goat (n = 10, 61.3 ± 6.5 kg). We set up the following conditions, including Circuit-Clamp (i.e., no pump support), 50% bypass, and 100% bypass. In these settings, CoF, MVO(2), pressure-volume area (PVA), and coronary vascular resistance (CVR) were measured. In 100% bypass, CoF, MVO(2), and PVA were all decreased significantly from clamp. While in 50% bypass, CoF and MVO(2) decreased from clamp, but not PVA. There was a significant 40% increase in CVR in 100% bypass from clamp. This CVR increase in 100% bypass was possibly due to mechanical collapse of coronary vascular bed itself by pump support or increased vascular tone through autoregulatory system. In clinical settings, we should adjust optimal pump speed so as not to cause this vascular collapse. However, to clarify autoregulatory system of the coronary perfusion, further investigation is ongoing in ischemic and heart failure models.
authors.affiliation: Department of Artificial Organs, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan. masandoo@hotmail.com
authors.forename: Masahiko
authors.initials: M
authors.lastname: Ando
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Takewa
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishimura
authors.forename: Kenji
authors.initials: K
authors.lastname: Yamazaki
authors.forename: Shunei
authors.initials: S
authors.lastname: Kyo
authors.forename: Minoru
authors.initials: M
authors.lastname: Ono
authors.forename: Tomonori
authors.initials: T
authors.lastname: Tsukiya
authors.forename: Toshihide
authors.initials: T
authors.lastname: Mizuno
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Taenaka
authors.forename: Eisuke
authors.initials: E
authors.lastname: Tatsumi
mesh_terms: D000818:Animals; D003326:Coronary Circulation / Q000502:physiology*; D004562:Electrocardiography; D006041:Goats / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006353:Heart-Assist Devices; D006439:Hemodynamics; D023421:Models, Animal; D008955:Models, Cardiovascular; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010101:Oxygen Consumption; D011673:Pulsatile Flow; D016277:Ventricular Function, Left / Q000502:physiology*; D017725:Ventricular Pressure
chemical_list: D010100:Oxygen