The Effects That Cardiac Motion has on Coronary Hemodynamics and Catheter Trackability Forces for the Treatment of Coronary Artery Disease: An In Vitro Assessment

Abstract

The coronary arterial tree experiences large displacements due to the contraction and expansion of the cardiac muscle and may influence coronary haemodynamics and stent placement. The accurate measurement of catheter trackability forces within physiological relevant test systems is required for optimum catheter design. The effects of cardiac motion on coronary flowrates, pressure drops, and stent delivery has not been previously experimentally assessed. A cardiac simulator was designed and manufactured which replicates physiological coronary flowrates and cardiac motion within a patient-specific geometry. A motorized delivery system delivered a commercially available coronary stent system and monitored the trackability forces along three phantom patient-specific thin walled compliant coronary vessels supported by a dynamic cardiac phantom model. Pressure drop variation is more sensitive to cardiac motion than outlet flowrates. Maximum pressure drops varied from 7 to 49 mmHg for a stenosis % area reduction of 56 to 90%. There was a strong positive linear correlation of cumulative trackability force with the cumulative curvature. The maximum trackability forces and curvature ranged from 0.24 to 0.87 N and 0.06 to 0.22 mm(-1) respectively for all three vessels. There were maximum and average percentage differences in trackability forces of (23-49%) and (1.9-5.2%) respectively when comparing a static pressure case with the inclusion of pulsatile flow and cardiac motion. Cardiac motion with pulsatile flow significantly altered (p value <0.001) the trackability forces along the delivery pathways with high local percentage variations and pressure drop measurements.

An in vitro Assessment of the Haemodynamic Features Occurring Within the True and False Lumens Separated by a Dissection Flap for a Patient-Specific Type B Aortic Dissection

“…A thin-walled flexible model was manufactured by the lost-wax process. Previous in vitro models for simulating blood flow through a single lumen within the coronaries ( 21 , 22 ), cerebral ( 23 – 27 ), and aortic aneurysms ( 28 – 30 ) were previously replicated in our laboratory. An in-house automatic injection system was designed and manufactured in order to control the injection process.…”

Methods for Evaluating Friction between Intravascular Device and Vascular Biomodel

“…Force applied to blood vessel model during automatic insertion. Morris et al [99] Commercially available coronary stent system vs. three phantom patient-specific thin-walled compliant coronary vessels.…”

“…Khoshbakht et al [98] showed that fluid flow can greatly change the tip contact force when the catheter is close to the left inferior pulmonary vein. Moreover, Morris et al [99] showed that cardiac motion with pulsatile flow significantly changes the insertion forces of a commercially available coronary stent system inserted into three patientspecific coronary artery models. After non-clinical performance tests, clinical studies are needed to demonstrate how the reduced insertion and retraction forces measured under simulated use conditions translate to ease of insertion scores and clinical outcomes (e.g., reduced potential for vessel wall injury) [83].…”