Hemodynamic outcomes after undersizing ring annuloplasty and focal suture annuloplasty for surgical repair of functional tricuspid regurgitation

Modified Clover Technique Using Automated Suture Placement and Securing Technology in a Passive Beating Heart Model

Tricuspid regurgitation (TR) is a prevalent finding in echocardiography and in case of severe disease is associated with impaired patient outcome. Clover repair offers a surgical solution that can be applied for the treatment of primary and secondary TR. An ex vivo passive beating porcine heart model was created to test a modified clover technique using automated suturing devices and to compare this approach to standard ring annuloplasty. Secondary TR was induced in 10 porcine hearts and the backflow of fluid was assessed. The primary endpoint of this study was regurgitant volume measured in mL at the site right atrial cannula. The baseline regurgitation was 43.3 ± 10.8 mL. The mean regurgitant volume was significantly reduced after all repair procedures to 22.2 ± 5.9 mL with isolated ring annuloplasty, 12 ± 3.9 mL with the modified clover, and 7.6 ± 3.4 mL with the combined procedure (p < 0.0001). The modified clover technique shows how to effectively reduce TR in an ex vivo model. This method may be suitable to facilitate tricuspid repair, especially for totally endoscopic valve surgery.

Surgical Treatment Strategy of Functional Tricuspid Regurgitation

Functional tricuspid regurgitation (FTR) is a common type of tricuspid regurgitation (TR), particularly in cases of left heart valve disease. Historically, cardiac surgeons have not placed much emphasis on FTR and instead focused primarily on managing left heart valve disease. However, as research has progressed, it has become evident that severe TR significantly impacts the prognosis of heart valve surgery. Furthermore, significant improvements in postoperative cardiac function and quality of life have been observed when addressing the tricuspid valve alongside left heart disease management. This article aims to review current approaches for and timing of the surgical management of FTR while also analyzing the limitations of existing tricuspid surgical strategies.

A tissue-silicone integrated simulator for right ventricular pulsatile circulation with severe functional tricuspid regurgitation

There is a great demand for development of a functional tricuspid regurgitation (FTR) model for accelerating development and preclinical study of tricuspid interventional repair devices. This study aimed to develop a severe FTR model by creating a tissue-silicone integrated right ventricular pulsatile circulatory simulator. The simulator incorporates the porcine tricuspid annulus, valve leaflets, chordae tendineae, papillary muscles, and right ventricular wall as one continuous piece of tissue, thereby preserving essential anatomical relationships of the tricuspid valve (TV) complex. We dilated the TV annulus with collagenolytic enzymes under applying stepwise dilation, and successfully achieved a severe FTR model with a regurgitant volume of 45 ± 9 mL/beat and a flow jet area of 15.8 ± 2.3 cm2 (n = 6). Compared to a normal model, the severe FTR model exhibited a larger annular circumference (133.1 ± 8.2 mm vs. 115.7 ± 5.5 mm; p = 0.009) and lower coaptation height (6.6 ± 1.0 mm vs. 17.7 ± 1.3 mm; p = 0.003). Following the De-Vega annular augmentation procedure to the severe FTR model, a significant reduction in regurgitant volume and flow jet area were observed. This severe FTR model may open new avenues for the development and evaluation of transcatheter TV devices.

Dynamic Coronary Blood Flow Velocity and Wall Shear Stress Estimation Using Ultrasound in an Ex Vivo Porcine Heart

PURPOSE

Wall shear stress (WSS) is a critically important physical factor contributing to atherosclerosis. Mapping the spatial distribution of local, oscillatory WSS can identify important mechanisms underlying the progression of coronary artery disease.

METHODS

In this study, blood flow velocity and time-varying WSS were estimated in the left anterior descending (LAD) coronary artery of an ex vivo beating porcine heart using ultrasound with an 18 MHz linear array transducer aligned with the LAD in a forward-viewing orientation. A pulsatile heart loop with physiologically-accurate flow was created using a pulsatile pump. The coronary artery wall motion was compensated using a local block matching technique. Next, 2D and 3D velocity magnitude and WSS maps in the LAD coronary artery were estimated at different time points in the cardiac cycle using an ultrafast Doppler approach. The blood flow velocity estimated using the presented approach was compared with a commercially-available, calibrated single element blood flow velocity measurement system.

RESULTS

The resulting root mean square error (RMSE) of 2D velocity magnitude acquired from a high frequency, linear array transducer was less than 8% of the maximum velocity estimated by the commercial system.

CONCLUSION

When implemented in a forward-viewing intravascular ultrasound device, the presented approach will enable dynamic estimation of WSS, an indicator of plaque vulnerability in coronary arteries.