Outpatient Grip Strength Measurement Predicts Survival, Perioperative Adverse Events, and Nonhome Discharge Among Patients With Vascular Disease

Abstract

magnetic resonance imaging. Gross qualification of aortic flows was performed using dye injection and computed flow visualization, which allows for particle tracing using the acquired magnetic resonance velocities. Whole aortic contours were segmented and centerlines calculated in each. Quantitative analyses were performed at five planes taken along the dissection at locations 0%, 25%, 50%, 75%, and 100% of the longitudinal extent of the intimal flap. Absolute flow rates were calculated by integrating velocities across individual luminal cross-sectional areas. Relative luminal flow rates were then calculated as the relative proportion of these absolute rates to their sum (total aortic flow rate). Maximal flow velocities at peak systole were identified in false lumen sections as flows in these regions were near 0 when grafted. Flow reversal in these sections was quantified via the reverse flow index, calculated as in Fig 1, I, with Q reverse being the total flow back to the heart, Q forward the total flow toward the systemic circulation, and T the length of the cardiac cycle (1 second). This quantity represents the amount of blood volume traveling retrograde from a given slice compared with the total amount of blood leaving the slice across the cardiac cycle. True lumen flow rates in grafted segments were compared with flow rates in aorta devoid of dissection using an unpaired two-tailed Student t-test. Points along the aortic contour, along with the previously derived centerlines, were used to compute wall shear stress using a finite difference method. This allowed for quantification of oscillatory shear index, a surrogate for prothrombotic shear stress regimes (Fig 1, J), in which the numerator represents the overall shear directed against the forward flow direction, and the denominator the total shear at a given wall point. This quantity has been shown to correlate with regions of atherogenesis in both carotid artery and abdominal aorta. Shear maps were then created by unwrapping aortic contours along the centerline to improve gross visualization and comparison.Results: In all experimental groups, complete false lumen obliteration was achieved in the grafted region. At these locations, neither intimal flap nor false lumen was identifiable. Analysis of cross-sectional slices through these locations revealed relatively parabolic flow profiles in the true (total) lumen, with representative maximal velocities of 30.4 6 8.4 cm/second in the case of single graft deployment. No significant difference was found between flow rates in the true lumen of these segments and undissected aorta (P > .05). Partially covered flap segments between the distal extent of endografts and subsequent fenestrations acted as blind pouches creating retrograde filling from the true lumen (Fig 2, B). Although a false lumen could be visualized in these sections, these areas of residual false lumen were characterized by low velocity flows (maximum velocity, 5.8 6 2.7 cm/second in the single graft condition) with decreased flow rates approachin...