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Hemodynamics and Wall Mechanics after Stent Placement in Swine Iliac Arteries: Comparative Results from Six Stent Designs¹

¹ From the Hemodynamics and Cardiovascular Mechanics Laboratory, (P.H.R., H.B., A.F.) and the Departments of Radiology (A.B.C., G.M., J.M.B.) and Vascular Surgery (C.V., P.P.), Faculte de Medicine, 27 boulevard Jean-Moulin, F-13385 Marseille 5, France. Received March 24, 1998; revision requested June 17; final revision received December 30; accepted March 23, 1999. Address reprint requests to P.H.R. (e-mail: lab.hmcv@medecine.univ-mrs.fr).

View larger version (155K): [in a new window]   Figure 1a. (a) Digital radiographs show the six stents deployed in the iliac artery of pigs in this study. The Strecker, Symphony, Wallstent, Memotherm, and Palmaz-Schatz stents are in the left iliac artery; the Cragg stent is in the right iliac artery. The two black dots at the proximal end of the Memotherm stent are radiopaque piezoelectric crystals embedded in the in situ diameter-measurement probe and the guiding catheter (which were withdrawn to the aorta during measurement); the tip of the pressure-measurement probe is emerging from the stent. (b) Angiogram shows the swine aorta and iliac and femoral arteries 4 days after implantation of a Palmaz-Schatz stent in the left iliac artery. Stent implantation was centered between the aortic trifurcation and the bifurcation between the superficial femoral and profunda femoris arteries (arrowheads). Note the early branching from the common iliac artery of the circumflex iliac artery (arrow), which was further ligated during investigation of hemodynamics and wall mechanics.

View larger version (154K): [in a new window]   Figure 1b. (a) Digital radiographs show the six stents deployed in the iliac artery of pigs in this study. The Strecker, Symphony, Wallstent, Memotherm, and Palmaz-Schatz stents are in the left iliac artery; the Cragg stent is in the right iliac artery. The two black dots at the proximal end of the Memotherm stent are radiopaque piezoelectric crystals embedded in the in situ diameter-measurement probe and the guiding catheter (which were withdrawn to the aorta during measurement); the tip of the pressure-measurement probe is emerging from the stent. (b) Angiogram shows the swine aorta and iliac and femoral arteries 4 days after implantation of a Palmaz-Schatz stent in the left iliac artery. Stent implantation was centered between the aortic trifurcation and the bifurcation between the superficial femoral and profunda femoris arteries (arrowheads). Note the early branching from the common iliac artery of the circumflex iliac artery (arrow), which was further ligated during investigation of hemodynamics and wall mechanics.

View larger version (28K): [in a new window]   Figure 2. Pressure-flow rate (P-Q, top) and pressure-diameter (P-Di, bottom) hysteresis loops obtained in the left iliac artery of a control pig. Note predominance of the elastic behavior over the viscous component in the control iliac artery, as illustrated by the large long axis-to-short axis ratio in the pressure-diameter hysteresis curve. This is in contrast to the pressure-flow rate hysteresis curve, where there is a short period of flow acceleration, with the maximum flow attained before the maximum pressure. IG255DE3, IG255DI3 = animal identification codes.

View larger version (13K): [in a new window]   Figure 3a. Results of Palmaz-Schatz stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Flow pulsatility is flattened downstream from the stent (I5) and in the contralateral artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Note the decreased compliance (Co) and pulsatility (D) and the increased Young (Ep) and incremental (Einc) elastic moduli downstream from the stent (I5) and in the contralateral iliac artery (Ic). ArS = arterial wall stiffness, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. For measurements obtained distal to the stent, the pressure-diameter loop is shortened, and the pressure-flow rate loop is flattened. These results reflect flow flattening and wall stiffening below the stent. IG212Di1, IG212Di5, ID259DE1, ID259DE5 = animal identification codes.

View larger version (34K): [in a new window]   Figure 3b. Results of Palmaz-Schatz stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Flow pulsatility is flattened downstream from the stent (I5) and in the contralateral artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Note the decreased compliance (Co) and pulsatility (D) and the increased Young (Ep) and incremental (Einc) elastic moduli downstream from the stent (I5) and in the contralateral iliac artery (Ic). ArS = arterial wall stiffness, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. For measurements obtained distal to the stent, the pressure-diameter loop is shortened, and the pressure-flow rate loop is flattened. These results reflect flow flattening and wall stiffening below the stent. IG212Di1, IG212Di5, ID259DE1, ID259DE5 = animal identification codes.

View larger version (21K): [in a new window]   Figure 3c. Results of Palmaz-Schatz stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Flow pulsatility is flattened downstream from the stent (I5) and in the contralateral artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Note the decreased compliance (Co) and pulsatility (D) and the increased Young (Ep) and incremental (Einc) elastic moduli downstream from the stent (I5) and in the contralateral iliac artery (Ic). ArS = arterial wall stiffness, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. For measurements obtained distal to the stent, the pressure-diameter loop is shortened, and the pressure-flow rate loop is flattened. These results reflect flow flattening and wall stiffening below the stent. IG212Di1, IG212Di5, ID259DE1, ID259DE5 = animal identification codes.

View larger version (14K): [in a new window]   Figure 4a. Results of Memotherm stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note the increase in flow pulsatility (due to decreased diastolic flow) downstream from the stent (I5) and in the contralateral iliac artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Note the increased compliance (Co) and pulsatility (D) and the decreased wall stiffness (ArS) and Young (Ep) and incremental (Einc) elastic moduli downstream from the stent (I5) and in the contralateral iliac artery (Ic). HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note the lengthening of the pressure-diameter loop and the broadening of the pressure-flow rate loop. These results reflect increased flow pulsatility and decreased wall stiffening below the stent. ID251DE1, ID251DE5, ID251Di1, ID251Di5 = animal identification codes.

View larger version (38K): [in a new window]   Figure 4b. Results of Memotherm stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note the increase in flow pulsatility (due to decreased diastolic flow) downstream from the stent (I5) and in the contralateral iliac artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Note the increased compliance (Co) and pulsatility (D) and the decreased wall stiffness (ArS) and Young (Ep) and incremental (Einc) elastic moduli downstream from the stent (I5) and in the contralateral iliac artery (Ic). HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note the lengthening of the pressure-diameter loop and the broadening of the pressure-flow rate loop. These results reflect increased flow pulsatility and decreased wall stiffening below the stent. ID251DE1, ID251DE5, ID251Di1, ID251Di5 = animal identification codes.

View larger version (21K): [in a new window]   Figure 4c. Results of Memotherm stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note the increase in flow pulsatility (due to decreased diastolic flow) downstream from the stent (I5) and in the contralateral iliac artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Note the increased compliance (Co) and pulsatility (D) and the decreased wall stiffness (ArS) and Young (Ep) and incremental (Einc) elastic moduli downstream from the stent (I5) and in the contralateral iliac artery (Ic). HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note the lengthening of the pressure-diameter loop and the broadening of the pressure-flow rate loop. These results reflect increased flow pulsatility and decreased wall stiffening below the stent. ID251DE1, ID251DE5, ID251Di1, ID251Di5 = animal identification codes.

View larger version (13K): [in a new window]   Figure 5a. Results of Wallstent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note that although changes in flow rates occurred within the stent, there were no significant changes in flow rates downstream from the stent (I5) or in the contralateral iliac artery (Ic), as compared with results in the control pigs (IC). (b) Bar graphs show hemodynamic and wall mechanical results. Note that downstream from the stent (I5) and in the contralateral iliac artery (Ic), compliance (Co) and wall pulsatility (D) were only slightly decreased and wall stiffness (ArS) remained unchanged, whereas major changes in these parameters occurred within the stent. Einc = incremental elastic modulus, Ep = Young elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. The slope of the pressure-flow rate loop is increased for measurements obtained downstream from the stent, which indicates that the flow wave accelerated relative to the pressure wave in early systole. Thinning of the pressure-diameter loop for measurements obtained downstream from the stent indicates that the diameter wave more closely followed the pressure wave than it did upstream from the stent. IG216DE1, IG216DE5, IG216Di1, IG216Di5 = animal identification codes.

View larger version (36K): [in a new window]   Figure 5b. Results of Wallstent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note that although changes in flow rates occurred within the stent, there were no significant changes in flow rates downstream from the stent (I5) or in the contralateral iliac artery (Ic), as compared with results in the control pigs (IC). (b) Bar graphs show hemodynamic and wall mechanical results. Note that downstream from the stent (I5) and in the contralateral iliac artery (Ic), compliance (Co) and wall pulsatility (D) were only slightly decreased and wall stiffness (ArS) remained unchanged, whereas major changes in these parameters occurred within the stent. Einc = incremental elastic modulus, Ep = Young elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. The slope of the pressure-flow rate loop is increased for measurements obtained downstream from the stent, which indicates that the flow wave accelerated relative to the pressure wave in early systole. Thinning of the pressure-diameter loop for measurements obtained downstream from the stent indicates that the diameter wave more closely followed the pressure wave than it did upstream from the stent. IG216DE1, IG216DE5, IG216Di1, IG216Di5 = animal identification codes.

View larger version (22K): [in a new window]   Figure 5c. Results of Wallstent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note that although changes in flow rates occurred within the stent, there were no significant changes in flow rates downstream from the stent (I5) or in the contralateral iliac artery (Ic), as compared with results in the control pigs (IC). (b) Bar graphs show hemodynamic and wall mechanical results. Note that downstream from the stent (I5) and in the contralateral iliac artery (Ic), compliance (Co) and wall pulsatility (D) were only slightly decreased and wall stiffness (ArS) remained unchanged, whereas major changes in these parameters occurred within the stent. Einc = incremental elastic modulus, Ep = Young elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. The slope of the pressure-flow rate loop is increased for measurements obtained downstream from the stent, which indicates that the flow wave accelerated relative to the pressure wave in early systole. Thinning of the pressure-diameter loop for measurements obtained downstream from the stent indicates that the diameter wave more closely followed the pressure wave than it did upstream from the stent. IG216DE1, IG216DE5, IG216Di1, IG216Di5 = animal identification codes.

View larger version (12K): [in a new window]   Figure 6a. Results of Strecker stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note the increased flow rates in the contralateral iliac artery (Ic), to the detriment of flow rates in the artery with the stent. The pulsatility remained proportionally unchanged. (b) Bar graphs show hemodynamic and wall mechanical results. Downstream from the stent (I5) and in the contralateral iliac artery (Ic), compliance (Co) and wall pulsatility (D) are markedly decreased, and wall stiffness (ArS) is markedly increased. Einc = incremental elastic modulus, Ep = Young elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note that the profiles of the hysteresis loops are retained but are substantially decreased form measurements obtained downstream from the stent. IG266DE1, IG266DE5, IG266Di1, IG266Di5 = animal identification codes.

View larger version (40K): [in a new window]   Figure 6b. Results of Strecker stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note the increased flow rates in the contralateral iliac artery (Ic), to the detriment of flow rates in the artery with the stent. The pulsatility remained proportionally unchanged. (b) Bar graphs show hemodynamic and wall mechanical results. Downstream from the stent (I5) and in the contralateral iliac artery (Ic), compliance (Co) and wall pulsatility (D) are markedly decreased, and wall stiffness (ArS) is markedly increased. Einc = incremental elastic modulus, Ep = Young elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note that the profiles of the hysteresis loops are retained but are substantially decreased form measurements obtained downstream from the stent. IG266DE1, IG266DE5, IG266Di1, IG266Di5 = animal identification codes.

View larger version (23K): [in a new window]   Figure 6c. Results of Strecker stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note the increased flow rates in the contralateral iliac artery (Ic), to the detriment of flow rates in the artery with the stent. The pulsatility remained proportionally unchanged. (b) Bar graphs show hemodynamic and wall mechanical results. Downstream from the stent (I5) and in the contralateral iliac artery (Ic), compliance (Co) and wall pulsatility (D) are markedly decreased, and wall stiffness (ArS) is markedly increased. Einc = incremental elastic modulus, Ep = Young elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance, m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note that the profiles of the hysteresis loops are retained but are substantially decreased form measurements obtained downstream from the stent. IG266DE1, IG266DE5, IG266Di1, IG266Di5 = animal identification codes.

View larger version (12K): [in a new window]   Figure 7a. Results of Symphony stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note that the flow pulsatility profile was maintained but at a lower level downstream from the stent, with no flow imbalance in the contralateral iliac artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Stress in the middle part of the arterial wall (m) within the stent (I3) remained normal, and compliance (Co) and wall pulsatility (D) were reduced downstream from the stent (I5). ArS = wall stiffness, Einc = incremental elastic modulus, Ep = Young elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note the well-matched decreases in both hysteresis loops for measurements obtained downstream from the stent. IG267DE1, IG267DE5, IG267Di1, IG267Di5 = animal identification codes.

View larger version (40K): [in a new window]   Figure 7b. Results of Symphony stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note that the flow pulsatility profile was maintained but at a lower level downstream from the stent, with no flow imbalance in the contralateral iliac artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Stress in the middle part of the arterial wall (m) within the stent (I3) remained normal, and compliance (Co) and wall pulsatility (D) were reduced downstream from the stent (I5). ArS = wall stiffness, Einc = incremental elastic modulus, Ep = Young elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note the well-matched decreases in both hysteresis loops for measurements obtained downstream from the stent. IG267DE1, IG267DE5, IG267Di1, IG267Di5 = animal identification codes.

View larger version (21K): [in a new window]   Figure 7c. Results of Symphony stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note that the flow pulsatility profile was maintained but at a lower level downstream from the stent, with no flow imbalance in the contralateral iliac artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Stress in the middle part of the arterial wall (m) within the stent (I3) remained normal, and compliance (Co) and wall pulsatility (D) were reduced downstream from the stent (I5). ArS = wall stiffness, Einc = incremental elastic modulus, Ep = Young elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note the well-matched decreases in both hysteresis loops for measurements obtained downstream from the stent. IG267DE1, IG267DE5, IG267Di1, IG267Di5 = animal identification codes.

View larger version (13K): [in a new window]   Figure 8a. Results of Cragg stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note the increased mean flow rate in the artery with the stent and, conversely, the decreased mean flow rate in the contralateral artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Compliance (Co) and pulsatility (D) are increased, and wall stiffness (ArS) and Young elastic modulus (Ep) are decreased downstream from the stent (I5) but not in the contralateral iliac artery (Ic). Einc = incremental elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note that both hysteresis loops returned to control shapes for measurements obtained downstream from the stent, although both were flattened for measurements above the stent. IG272DE1, IG272DE5, IG281Di1, IG281Di5 = animal identification codes.

View larger version (36K): [in a new window]   Figure 8b. Results of Cragg stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note the increased mean flow rate in the artery with the stent and, conversely, the decreased mean flow rate in the contralateral artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Compliance (Co) and pulsatility (D) are increased, and wall stiffness (ArS) and Young elastic modulus (Ep) are decreased downstream from the stent (I5) but not in the contralateral iliac artery (Ic). Einc = incremental elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note that both hysteresis loops returned to control shapes for measurements obtained downstream from the stent, although both were flattened for measurements above the stent. IG272DE1, IG272DE5, IG281Di1, IG281Di5 = animal identification codes.

View larger version (22K): [in a new window]   Figure 8c. Results of Cragg stent placement in three pigs, in comparison with results in the untreated contralateral artery (Ic) and in untreated control pigs (IC). Measurements were performed 1 cm above (I1) and 0.5 cm below (I2) the proximal end of the stent, at the middle of the stent (I3), and 0.5 cm above (I4) and 1 cm below (I5) the distal end of the stent. (a) Bar graphs of hemodynamic results show maximum blood flow rate (black bars), minimum blood flow rate (white bars), flow pulsatility (dotted bars), and mean flow rate (gray bars). Note the increased mean flow rate in the artery with the stent and, conversely, the decreased mean flow rate in the contralateral artery (Ic). (b) Bar graphs show hemodynamic and wall mechanical results. Compliance (Co) and pulsatility (D) are increased, and wall stiffness (ArS) and Young elastic modulus (Ep) are decreased downstream from the stent (I5) but not in the contralateral iliac artery (Ic). Einc = incremental elastic modulus, HPR = peripheral resistance, PR = relative pulsatility, Zc = input impedance m = stress in middle part of arterial wall. (c) Typical pressure-flow rate (P-Q) and pressure-diameter (P-Di) hysteresis loops for measurements obtained 1 cm above (top left and bottom left) and 1 cm below (top right and bottom right) the stent. Note that both hysteresis loops returned to control shapes for measurements obtained downstream from the stent, although both were flattened for measurements above the stent. IG272DE1, IG272DE5, IG281Di1, IG281Di5 = animal identification codes.