Four-Dimensional Aortic Blood Flow Patterns in Thoracic Aortic Grafts

Abstract

Time-resolved cardiac gated three-directional velocity data obtained with magnetic resonance velocity-encoded phase contrast sequences were used to study blood flow patterns in thoracic aortic grafts. Twelve patients were studied, 6 with traumatic descending aortic pseudoaneurysms, 3 with atherosclerotic aneurysms, and 3 with dissecting aneurysms. All grafts had an inflow jet; outflow jet; and/or vortices proximal, in, or distal to the graft. Flow abnormalities were generally mild in the descending aortic traumatic pseudoaneurysms seen in young people. The atherosclerotic aneurysms seen in elderly patients had the most abnormal flows with multiple vortices in and outside the graft. Blood persisted up to one and a half heartbeats in some vortices and took three to five heartbeats to flow from ascending to descending aorta compared with two to three in age-matched normal subjects. Rather large energy losses, probably up to 33% of the cardiac output in our worst case, may occur in thoracic aortic grafts.

Non-Newtonian perspectives on pulsatile blood-analog flows in a 180° curved artery model

“…The importance of this study lies in the hypotheses posed in literature concerning the relation between nature and persistence of secondary flow structures to cardiovascular diseases such as atherosclerosis and arterial aneurysms. [36][37][38][39][40][41][42][43] Moreover, if seeking to understand these flow structures developing in our arteries, it is crucial to know the effect of neglecting the non-Newtonian behavior of blood on these structures, especially when considering large arteries as it is common to assume blood to be Newtonian. Via the numerical simulations, the effects of the non-Newtonian viscosity on the flow structures are elucidated.…”

ACCF/ACR/AHA/NASCI/SCMR 2010 Expert Consensus Document on Cardiovascular Magnetic Resonance

“…Clinically, PC-CMR measures of blood flow velocity have been acquired in the aorta (43), the pulmonary arteries (45), coronary artery bypass grafts (46), and across heart valves (47). These data are useful for identifying abnormalities of blood flow in patients with diseases of the aorta (aortic dissection, aneurysms, or coarctation) (46), congenital heart disease (either through native vessels or surgically placed conduits) (48,49), or stenotic/regurgitant valve lesions (3).…”

“…These data are useful for identifying abnormalities of blood flow in patients with diseases of the aorta (aortic dissection, aneurysms, or coarctation) (46), congenital heart disease (either through native vessels or surgically placed conduits) (48,49), or stenotic/regurgitant valve lesions (3). …”

Transcatheter closure of the patent ductus arteriosus

“…The standard retrospectively gated velocity‐encoded phase‐contrast CINE sequence (2dphcon), although requiring longer acquisition times, yielded more accurate and precise velocity measurements, and at higher temporal resolution. This velocity‐encoded phase‐contrast CINE sequence has been used extensively and tested for accuracy and precision by us and other groups over many years with very consistent results (3–6, 11, 13–23).…”