Systemic Arterial Response to Exercise in Patients With Aortic Valve Stenosis
Background-Systemic arterial hemodynamics play an important role in the assessment of the severity and hemodynamic consequences of aortic valve stenosis (AVS). Methods and Results-Systemic vascular resistance, total arterial compliance, effective arterial elastance, and aortic characteristic impedance were derived from high-fidelity catheter recordings of ascending aortic pressure and blood flow velocity at rest and with supine bicycle exercise in 18 patients with AVS and 11 control subjects.
... control subjects. Mean aortic pressure was similar between groups. At rest, systemic vascular resistance (AVS patients, 1426Ϯ318 dynes · s · cm Ϫ5 ; control subjects, 107Ϯ228 dynes · s · cm Ϫ5 ; PϽ0.01), arterial elastance (AVS patients, 1.38Ϯ0.36 mm Hg/mL; control subject, 0.99Ϯ0.15 mm Hg/mL; PϽ0.002), and aortic characteristic impedance (AVS patients, 107Ϯ23 dynes · s · cm Ϫ5 ; control subjects, 76Ϯ30 dynes · s · cm Ϫ5 ; PϽ0.01) were increased, whereas total arterial compliance was lower (AVS patients, 0.737Ϯ0.19ϫ10 Ϫ3 cm 5 /dyne; control subjects, 1.155Ϯ0.27ϫ10 Ϫ3 cm 5 /dyne; PϽ0.001) in AVS. With exercise, total arterial compliance increased in control subjects (rest, 1.155Ϯ0.27ϫ10 Ϫ3 cm 5 /dyne; exercise, 1.421Ϯ0.49ϫ10 Ϫ3 cm 5 /dyne; PϽ0.05) but did not change in AVS patients (rest, 0.737Ϯ0.19ϫ10 Ϫ3 cm 5 /dyne; exercise, 0.769Ϯ0.21ϫ10 Ϫ3 cm 5 /dyne; Pϭ0.2). Arterial elastance increased on exercise in AVS patients (rest, 1.38Ϯ0.36 mm Hg/mL; exercise, 1.57Ϯ0.44; PϽ0.01). Aortic characteristic impedance remained elevated on exercise (AVS patients, 122Ϯ30 dynes · s · cm Ϫ5 ; control subjects, 80Ϯ43 dynes · s · cm Ϫ5 ; Pϭ0.01). Stroke flow increased significantly in both AVS patients (rest, 229Ϯ69 mL/s; exercise, 256Ϯ78 mL/s; PϽ0.01) and control subjects (rest, 230Ϯ37 mL/s; exercise, 406Ϯ69 mL/s; PϽ0.001), although the increment was much attenuated in AVS. On multiple regression, the increase in stroke flow was related to the decrease in systemic vascular resistance (Pϭ0.03), increase in total arterial compliance (Pϭ0.03), and decrease in arterial elastance (Pϭ0.02). Conclusions-These results indicate a pressure-independent increase in the steady and pulsatile components of the arterial load in patients with AVS under resting conditions. Persistent "stiffening" of the arterial system is an important contributor to the diminished stroke output response to exercise in AVS. (Circulation. 2009;119:996-1004.) Figure 5. A, The relationship between TAC-1 and TAC-2 in control patients at rest was statistically significant (r 2 ϭ0.69, PϽ0.001). B, The relationship between TAC-1 and TAC-2 in AVS patients at rest was statistically significant (r 2 ϭ0.98; PϽ0.0001).