Transcatheter aortic valve replacement aortic root orientation: implications for future coronary access and redo transcatheter aortic valve replacement

Effect of TAVR commissural alignment on coronary flow: A fluid-structure interaction analysis

BACKGROUND AND OBJECTIVES

Coronary obstruction is a complication that may affect patients receiving Transcatheter Aortic Valve Replacement (TAVR), with catastrophic consequences and long-term negative effects. To enable healthy coronary perfusion, it is fundamental to appropriately position the device with respect to the coronary ostia. Nonetheless, most TAVR delivery systems do not control commissural alignment to do so. Moreover, no in silico study has directly assessed the effect of commissural alignment on coronary perfusion. This work aims to evaluate the effect of TAVR commissural alignment on coronary perfusion and device performance.

METHODS

A two-way computational fluid-structure interaction model is used to predict coronary perfusion at different commissural alignments. Moreover, in each scenario, hemodynamic biomarkers are evaluated to assess device performance.

RESULTS

Commissural misalignment is shown to reduce the total coronary perfusion by -3.2% and the flow rate to a single coronary branch by -6.8%. It is also observed to impair valvular function by reducing the systolic geometric orifice area by -2.5% and increasing the systolic transvalvular pressure gradients by +5.3% and the diastolic leaflet stresses by +16.0%.

CONCLUSIONS

The present TAVR patient model indicates that coronary perfusion, hemodynamic and structural performance are minimized when the prosthesis commissures are fully misaligned with the native ones. These results support the importance of enabling axial control in new TAVR delivery catheter systems and defining recommended values of commissural alignment in upcoming clinical treatment guidelines.

Impact of blood pressure on coronary perfusion and valvular hemodynamics after aortic valve replacement

OBJECTIVE

Our objective was to evaluate the impact of various blood pressures (BPs) on coronary perfusion and valvular hemodynamics following aortic valve replacement (AVR).

BACKGROUND

Lower systolic and diastolic (SBP/DBP) pressures from the recommended optimal target range of SBP < 120-130 mmHg and DBP < 80 mmHg after AVR have been independently associated with increased cardiovascular and all-cause mortality.

METHODS

The hemodynamic assessment of a 26 mm SAPIEN 3 transcatheter aortic valve (TAV), 29 mm Evolut R TAV, and 25 mm Magna Ease surgical aortic valve (SAV) was performed in a pulsed left heart simulator with varying SBP, DBP, and heart rate (HR) conditions (60 and 120 bpm) at 5 L/min cardiac output (CO). Average coronary flow (CF), effective orifice areas (EOAs), and valvulo-arterial impedance (Zva) were calculated.

RESULTS

At HR of 60 bpm, at SBP < 120 mmHg and DBP < 60 mmHg, CF decreased below the physiological lower limit with several different valves. Zva and EOA were found to increase and decrease respectively with increasing SBP and DBP. The same results were found with an HR of 120 bpm. The trends of CF variation with BP were similar in all valves however the drop below the lower physiological CF limit was valve dependent.

CONCLUSION

In a controlled in vitro system, with different aortic valve prostheses in place, CF decreased below the physiologic minimum when SBP and DBP were in the range targeted by blood pressure guidelines. Combined with recent observations from patients treated with AVR, these findings underscore the need for additional studies to identify the optimal BP in patients treated with AVR for AS.

Transcatheter Aortic Valve Replacement with a Self-Expanding Prosthesis

The self-expanding transcatheter heart valve (Medtronic Cardiovascular Corevalve and Evolut) is a supra-annular, trileafet porcine pericardial valves on a diamond lattice nickel-titanium alloy frame. The TAVR device has undergone significant improvements in design and procedural techniques to further increase safety, efficacy, and durability since they it was first released. Unique design characteristics, as well as patient and procedural factors, favor self-expanding over balloon-expandable prostheses in certain situations. The self-expanding transcatheter heart valve has proven to be an excellent option for severe aortic stenosis patients with any level of surgical risk and preliminary data suggest a comparable durability to surgical tissue valves.

Cusp Overlap Technique: Should It Become the Standard Implantation Technique for Self-expanding Valves?

PURPOSE OF REVIEW

Accurate imaging of the aortic root during valve implantation is crucial for proper prosthesis positioning during TAVR. The purpose of this review was to determine if routine use of the cusp-overlap view should be adopted for self-expanding valves.

RECENT FINDINGS

The use of the cusp-overlap view with the Evolut, Portico, ACURATE neo/neo2, and JenaValve systems is associated with lower post-procedural new permanent pacemaker implantation rates when compared with the standard 3-cusp view, presumably due to more precise valve implantation relative to the conduction system by the non-coronary cusp. By elongating the left ventricular outflow tract and accentuating the right-non commissure in the center of the fluoroscopic view, the cusp-overlap technique allows operators to more precisely control the prosthesis implant depth during self-expanding valve deployment. While the early experience with this approach in Evolut TAVR has been promising, the results of larger studies with longer follow-up across multiple self-expanding systems are warranted.

Current challenges in TAVI: neo-commissural alignment to mimic more physiologic valve implantation

Commissural alignment during transcatheter aortic valve implantation (TAVI) has important clinical implications as TAVI expands to younger patients in whom lifetime treatment of aortic valve disease and coronary artery disease is of particular importance. Numerous studies have shown that lack of commissural alignment may adversely affect coronary reaccess and the feasibility of redo-TAVI in this patient population. To assess the risk of commissural misalignment more accurately, we have pioneered and validated the use of a preprocedural imaging protocol that determines valve orientation using multi-detector computed tomography-fluoroscopy co-registration. Furthermore, we have shown that a modified delivery system insertion technique during initial valve deployment results in improved commissural alignment and reduced coronary artery overlap following TAVI with a self-expanding device. However, numerous unanswered questions remain about the impact of commissural misalignment on balloon-expandable valve-in-valve TAVI, especially in patients with unfavorable aortic root anatomy. It is imperative that clinicians consider these anatomic, device-related, and procedure factors, among others, when evaluating patients for transcatheter therapies.