Unlike some interventional valve repair techniques, surgical techniques still encounter two unresolved challenges. First, although surgery has a broader technical arsenal, greater range of approaches, and more extensive experience, it remains reliant on performing procedures under cardioplegia conditions. The initial drawback is that surgical techniques necessitate extrapolating echocardiographic analysis to segmental analysis of the valve (aortic, mitral, or tricuspid), whereas, for example, interventional techniques like mitral or tricuspid clipping enable precise targeting due to the presence of the PISA and vena contracta. This limits the ability to add corrective or additional repairs immediately. The second challenge is that the positioning of the heart under cardioplegia differs from that required for proper valve closure, which aims to restore competence. Thus, while atrioventricular valves, which must close during systole, are repaired with the heart in diastolic arrest, the aortic valve, which should close under diastolic root pressurization, is repaired in an open position. 

In atrioventricular valve repair, the saline test has been proposed as a ventricular pressurization method to assess valve competence. Now a classic technique, it has garnered equal supporters and detractors. For many, good ventricular pressurization and competent valve display often predict favorable echocardiographic results. Conversely, confidence in the technique and completed coaptation surface corrections may warrant assessment even when the test outcome is unsatisfactory, independent of cardiopulmonary bypass. Numerous factors, including ventricular pressurization in diastole, pericardial traction, sternal retractor opening, and atrial exposure, may influence test results. Certain authors have noted that saline-filled left ventricles facilitate air ascent toward the aortic root, potentially leading to coronary air embolism. Thus, they suggest pressurization via antegrade cardioplegia administration, which, with an exposed mitral valve, will render the aortic valve incompetent and permit left ventricular pressurization. 

However, the aortic valve repair remains challenging as it is performed in an open field, making pressurization techniques for competence assessment more complex. Therefore, confidence in the procedure predominantly underlies evaluation post-cardiopulmonary bypass separation. Appropriate commissure reimplantation, free-edge length balance, restoration of normal root architecture, and, consequently, the coaptation surface all contribute to potential successful outcomes. Negative intraventricular pressure generation through aspiration via the vent catheter to mimic root pressurization has been suggested, though it further departs from replicating physiological conditions. 

In this context, a Dutch team describes their experience with a device for in-situ pressurization of the aortic root with saline solution to assess valvular competence. The device, seemingly a prototype with no commercial reference, comprises a cylinder pneumatically anchored to the conduit or ascending aorta. It seals with a pneumatic system, followed by saline infusion to achieve root pressurization. The infusion utilizes one of the extracorporeal circulation machine’s rotors, analogous to a cardioplegia line. Finally, an anti-reflux valve in the cylinder allows for thoracoscope introduction to observe valvular competence. The authors recommend using 10 mm thoracoscopes with a 30° angle, though 0° thoracoscopes are also viable. Competence evaluation is based on saline leakage (regurgitation) once Dacron graft porosity leakage is ruled out. Laboratory tests estimate the latter as minimal, approximately 2 cc/cm2/min, though no reference cut-off is provided. 

The center’s experience, initiated in 2019, involved 24 patients undergoing root reimplantation surgery. System pressurization reached 60-70 mmHg in 22 cases, with final echocardiographic aortic insufficiency grade 1+ or lower in all. Mean saline leakage was 90 cc/min. In 5 cases, the device prompted corrective valve repairs, while in two cases, valve replacement preceded further procedural continuation. Competence assessments were always conducted prior to coronary button reimplantation. 

The authors conclude that the device facilitates intraoperative evaluation of the repaired aortic valve under conditions closer to physiological pressurization, enabling targeted adjustments through direct visualization. Thus, the device can be a valuable tool for intraoperative aortic valve assessment during repair procedures, enhancing procedural predictability and efficiency. 

COMMENTARY:

The innovation capacity of this group is noteworthy. Though in initial stages, this tool appears promising for intraoperative corrective decision-making, similar to the role the saline test has long played for mitral and tricuspid valves. While it may require refinement before commercialization, many devices initially exhibited less ergonomics than they now offer. Consider the initial TAVI and TEVAR introducers, surgical arrhythmia ablation devices, pacemaker generators, and implantable ventricular assist devices, among others. 

Innovation is essential in our field, unprejudiced and beyond the “we’ve always done it this way” mentality. Some devices will find their path, others may not. However, innovation is not a straight line from idea to success; it involves many steps, including failures, before a project comes to fruition. 

The authors suggest the device is potentially applicable in any aortic valve analysis. While valuable for root reimplantation and remodeling techniques, it might also apply to isolated aortic valve repair or homograft/autograft (Ross) implantation. Nonetheless, the following precautions are advised without diminishing the authors’ optimism: 

– Application for native aortic root pressurization, as would occur in Ross, homograft, or isolated valve repair surgeries, has not been described, so device functionality in these contexts remains unknown. 

– In these surgeries, pressurization would occur with coronary ostia present, necessitating cardioplegia washout with saline. An alternative could involve crystalloid solution infusion for pressurization, though this might disrupt myocardial protection protocols. 

– Re-correction rate was under one-fourth of procedures, with structural valve issues in two cases likely prompting replacement without re-evaluation. Therefore, only in three of the 22 procedures did pressurized assessment influence corrective decisions (13%), with excellent subsequent echocardiographic results. 

– Assuming that any repaired valve’s competence alone equates to proper function is oversimplified. The opening (gradient), leaflet mobility with stress zones, coaptation reserve, and dynamic conditions all affirm successful repair. Thus, confirming a repaired aortic valve’s functionality under static root pressurization remains an imperfect evaluation. Although a “passive” valve compared to atrioventricular valves, the aortic root also exhibits systo-diastolic dynamics, reminding us of the saline test’s limitations discussed earlier. 

Hence, innovation is challenging, with more obstacles than victories. Nonetheless, it is necessary to advance cardiac surgery toward modernity. Its future partly depends on this progress, as innovation in competing fields won’t cease and has led them to their present accomplishments. Industry commitment is also a significant factor, but the drive of pioneers willing to publish such valuable experiences completes the synergy. Only thus can we envision a horizon where, deceptively, it seems everything has been invented. 

REFERENCE:

Arabkhani B, Sandker SC, Braun J, Hjortnaes J, van Brakel TJ, Koolbergen DR, et al. Aortic valve visualization and pressurization device: a novel device for intraoperative evaluation of aortic valve repair procedures. Eur J Cardiothorac Surg. 2023 Nov 1;64(5):ezad291. doi: 10.1093/ejcts/ezad291.