A New Approach to Myocardial Injury Adaptations: A Possible Solution for One of the Oldest Problems in Heart Surgery

Objectives: Since the beginning of cardiac surgery the problem of myocardial injury and its adaption is still unsolved. Myocardial injuries remain a high risk. Myocardial suture is successful under relief by the ECC and use of patches. Other surgical disciplines already use knotless anchor sutures to adapt muscular injuries. With a pig heart wall tension model the ideal bidirectional knotless anchor suture should be established in cardiac surgery.

Methods: The maximal holding force of a commonly used knotless anchor suture to the myocardium (3 cm) is gathered using a motor driven procedure on a high-resolution newton meter. 30 pig hearts were investigated (fresh and thawed organs up to 14 hour). To simulate the wall tension, we developed a pseudo beating heart model using two air driven intraventricular balloons (two additional to adjust the preload: LV 140 ± 10 mm Hg, RV 60 ± 10 mm Hg, 80 BPM). After 60 minutes of recording 4 standardized cuts was made (1 cm). The margins of the wounds are adapted to our bidirectional suture system. After that the measurement of the wall tension and the compliance of the suture system are videotaped for 60 minutes.

Result: The myocardial tearing strength is significantly different for each defined myocardial tissue part. The basal area (7.16 N) reveals the highest holding force in comparison to the midventricular section (6.53 N; p = 0.03) and the heart apex area (6.38 N; p = 0.003). Further there are force varieties between the right (7,01 N) and the left (6.39 N) ventricle (p = 0.0049). A difference between the anterior (6.83 N) and the posterior (6.56 N) wall could not been shown (p = 0.75). A precise distinction has to be made between suturing in parallel (6.9 N) or vertically (6.5 N) to the fibers (p = 0.03). With the pseudo beating heart model an easily repeatable wall tension model was created. The ventricular pressures are stable as well as the intracavitary pressures are.

Conclusion: We can show that this suture system is effective. Regardless, certain geometric improvements need to be made. The choice of the thread material must be reconsidered and be produced by a 3D printer. In vivo pig experiments are believed to start soon after considering those new advancements. Our ambition is to establish a new suture device in cardiac surgery and for treatment in preclinic worse case situations due to an injured beating heart (e.g., new possibility after outhouse Clamshell Thoracotomy).

Publication History

Article published online:
19 February 2021