Posts in Category: Intervention, Surgery, & Transplantation

Bioresorbable Scaffold: The Emerging Reality and Future Directions

Bioresorbable Scaffold: The Emerging Reality and Future Directions

Yohei Sotomi, Yoshinobu Onuma, Carlos Collet, Erhan Tenekecioglu, Renu Virmani, Neal S. Kleiman, Patrick W. Serruys

Strut thickness and platelet activation. The thick protruding strut disrupts the laminar flow and induces flow disturbances, and thereby endothelial shear stress (ESS) microgradients (upper panel). The shear microgradients can induce the formation of stabilized discoid platelet aggregates, the size of which is directly regulated by the magnitude and spatial distribution of the gradient.72,73 Shear microgradient–dependent platelet aggregation requires 3 principal features: shear acceleration phase, peak shear phase, and shear deceleration phase. During shear acceleration, platelets in the central regions of blood flow exposed to laminar flow (constant physiological shear) are suddenly accelerated through the shear microgradient. During the peak shear phase, a proportion of the discoid platelets that are accelerated into the peak shear zone adhere to exposed thrombogenic surfaces through platelet membrane glycoprotein (GP) Ib/IX/V. Exposure of these platelets to elevated hemodynamic drag leads to the extrusion of thin filamentous membrane tethers. Membrane tether formation initiates discoid platelet adhesion with the thrombogenic surface and also facilitates the recruitment of discoid platelets into the downstream deceleration zone. During the shear deceleration phase, platelets transitioning into the flow deceleration zone experience decreasing hemodynamic drag forces. Reduced shear within this zone progressively favors the formation of integrin αIIbβ3 adhesion contacts. Integrin αIIbβ3 engagement is associated with low-frequency calcium spikes that trigger tether restructuring, leading to the stabilization of discoid platelet aggregates. Ongoing discoid platelet recruitment drives the propagation of the thrombus in the downstream deceleration zone, which may in turn amplify the shear microgradient and promote further platelet aggregation. Thus, the shear microgradients caused by the thick struts induce platelet aggregation, formation of microthrombi with potential embolization, and micromyocardial necrosis (so-called a nidus of thrombus). The magnitude of flow disturbance depends on the degree of protrusion of the strut into the lumen. Therefore, thin struts could be a potential solution for the less flow disturbance and thus less thrombogenic status (lower panel). There is another cascade of von Willebrand factor (VWF)/GPIb activation, namely agglutination-elicited GPIb signaling.73 In contrast to shear stress–induced GPIb-elicited signaling, agglutination-elicited GPIb signaling that activates integrin αIIbβ3 requires thromboxane A2 (TXA2). Agglutination-elicited TXA2 production is independent of Ca2+ influx and mobilization of internal Ca2+ stores. [Powerpoint File]

Bioresorbable Scaffold: The Emerging Reality and Future Directions

Bioresorbable Scaffold: The Emerging Reality and Future Directions

Yohei Sotomi, Yoshinobu Onuma, Carlos Collet, Erhan Tenekecioglu, Renu Virmani, Neal S. Kleiman, Patrick W. Serruys

Design and optical coherence tomography (OCT) appearance of first and next generation bioresorbable scaffolds (BRSs). [Powerpoint File]

Current Interventional and Surgical Management of Congenital Heart Disease: Specific Focus on Valvular Disease and Cardiac Arrhythmias

Current Interventional and Surgical Management of Congenital Heart Disease: Specific Focus on Valvular Disease and Cardiac Arrhythmias

Kimberly A. Holst, Sameh M. Said, Timothy J. Nelson, Bryan C. Cannon, Joseph A. Dearani

Schematic representation of the possible lines of ablation to treat macro reentrant atrial tachycardia in the presence of various atrial anomalies associated with complex congenital heart disease. avn indicates atrioventricular node; CS, coronary sinus; FO, foramen ovale; HV, hepatic vein; IVC, inferior vena cava; LAA, left atrial appendage; LSVC, left superior vena cava; MV, mitral valve; PV, pulmonary valve; RAA, right atrial appendage; RSVC, right superior vena cava; TAPVR, total anomalous pulmonary venous return; and TV, tricuspid valve. Reproduced from Mavroudis et al53 with permission of the publisher. Copyright ©2008, The Society of Thoracic Surgeons. [Powerpoint File]

Current Status and Future Potential of Transcatheter Interventions in Congenital Heart Disease

Current Status and Future Potential of Transcatheter Interventions in Congenital Heart Disease

Damien P. Kenny, Ziyad M. Hijazi

Cartoon illustrating possible future strategies for the surgical management of newborns with congenital heart disease (CHD). If CHD is diagnosed prenatally, fetal cells may be harvested and induced pluripotent stem cells (iPS) generated; as an alternative, umbilical cord stem cells can be isolated at the time of birth. When diagnosis of CHD is made after birth or in babies who require a palliative surgical operation soon after birth, stem cells may be isolated from surgical cardiac leftovers. All these types of cells will allow the generation of a tissue-engineered graft endowed with growth and remodeling potential, necessary for the definitive correction of cardiac defects (Taken from Avolio et al99; Illustration Credit: Ben Smith). [Powerpoint File]

Current Status and Future Potential of Transcatheter Interventions in Congenital Heart Disease

Current Status and Future Potential of Transcatheter Interventions in Congenital Heart Disease

Damien P. Kenny, Ziyad M. Hijazi

Series of angiographic images demonstrating hybrid pulmonary valve replacement after plication of the main pulmonary artery in a patient with a significantly dilated right ventricular outflow tract (RVOT) after transannular patch repair of tetralogy of Fallot as an infant. A and B, Initial angiogram demonstrating dilated RVOT measuring 33 mm; (C) RVOT angiogram after main pulmonary artery (MPA) plication and placement of a prestent; and (D) MPA angiogram demonstrating valvular competence with no pulmonary incompetence after Melody valve placement. [Powerpoint File]

Current Status and Future Potential of Transcatheter Interventions in Congenital Heart Disease

Current Status and Future Potential of Transcatheter Interventions in Congenital Heart Disease

Damien P. Kenny, Ziyad M. Hijazi

Series of fetal echocardiography images demonstrating fetal aortic balloon valvuloplasty. A, Initial fetal echocardiogram demonstrating dilated left ventricle (LV) with narrow color jet seen across stenotic aortic valve; (B) introduction of needle into the cavity of the LV (white arrow signifies needle tip); (C) wire seen crossing the aortic valve (white arrow); and (D) inflation of balloon across the aortic valve (white arrow). [Powerpoint File]