title: Effects of two different anesthetic protocols on cardiac flow measured by two dimensional phase contrast magnetic resonance imaging.
abstract: Companion animals are routinely anesthetized or heavily sedated for cardiac MRI studies, however effects of varying anesthetic protocols on cardiac function measurements are incompletely understood. The purpose of this prospective study was to compare effects of two anesthetic protocols (Protocol A: Midazolam, fentanyl; Protocol B: Dexmedetomidine) on quantitative and qualitative blood flow values measured through the aortic, pulmonic, mitral, and tricuspid valves using two-dimensional phase contrast magnetic resonance imaging (2D PC MRI) in healthy dogs. Mean flow per heartbeat values through the pulmonary artery (Qp) and aorta (Qs) were compared to right and left ventricular stroke volumes (RVSV, LVSV) measured using a reference standard of 2D Cine balanced steady-state free precession MRI. Pulmonary to systemic flow ratio (Qp/Qs) was also calculated. Differences in flow and Qp/Qs values generated using 2D PC MRI did not differ between the two anesthetic protocols (P = 1). Mean differences between Qp and RVSV were 3.82 ml/beat (95% limits of agreement: 3.62, -11.26) and 1.9 ml/beat (-7.86, 11.66) for anesthesia protocols A and B, respectively. Mean differences between Qs and LVSV were 1.65 ml/beat (-5.04, 8.34) and 0.03 ml/beat (-4.65, 4.72) for anesthesia protocols A and B, respectively. Mild tricuspid or mitral reflux was seen in 2/10 dogs using 2D PC MRI. No aortic or pulmonic insufficiency was observed. Findings from the current study indicated that these two anesthetic protocols yield similar functional measures of cardiac blood flow using 2D PC MRI in healthy dogs. Future studies in clinically affected patients are needed.
authors.affiliation: VMTH DSS, UW-Madison, Madison, WI, 53726, USA.
authors.forename: Randi
authors.initials: R
authors.lastname: Drees
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Johnson
authors.forename: Rebecca L
authors.initials: RL
authors.lastname: Stepien
authors.forename: Alejandro
authors.initials: A
authors.lastname: Munoz Del Rio
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: François
mesh_terms: D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D000818:Animals; D001011:Aorta / Q000187:drug effects; D001021:Aortic Valve / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects*; D003287:Contrast Media; D020927:Dexmedetomidine / Q000008:administration & dosage; D004285:Dogs / Q000502:physiology*; D005283:Fentanyl / Q000008:administration & dosage; D006993:Hypnotics and Sedatives / Q000008:administration & dosage*; D019028:Magnetic Resonance Imaging, Cine / Q000662:veterinary; D008943:Mitral Valve / Q000187:drug effects; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000187:drug effects; D011664:Pulmonary Valve / Q000187:drug effects; D012039:Regional Blood Flow / Q000187:drug effects; D015203:Reproducibility of Results; D013318:Stroke Volume / Q000187:drug effects; D014261:Tricuspid Valve / Q000187:drug effects; D016277:Ventricular Function, Left / Q000187:drug effects; D016278:Ventricular Function, Right / Q000187:drug effects
chemical_list: D018686:Anesthetics, Intravenous; D003287:Contrast Media; D006993:Hypnotics and Sedatives; D020927:Dexmedetomidine; D005283:Fentanyl
keywords: aortic; dog; heart; mitral; pulmonic; tricuspid