Suture tie-down forces and cyclic contractile forces after an undersized tricuspid annuloplasty using a 3-dimensional rigid ring in an ovine model

OBJECTIVES This study was conducted to measure suture tie-down forces and evaluate cyclic contractile forces (CCFs) in beating hearts after undersized 3-dimensional (3D) rigid-ring tricuspid valve annuloplasty (TAP). METHODS Eight force transducers were attached to the 3D rigid TAP ring. Segments 1 to 8 were attached from the mid-septal to anterior-septal commissural area in a counterclockwise order. Two-sizes-down ring TAPs were performed in 6 sheep. Tie-down forces and CCF were recorded and analysed at the 8 annular segments and at 3 levels of peak right ventricular pressure (RVP: 30, 50 and 70 mmHg). RESULTS The overall average tie-down forces and CCF were 4.34 ± 2.26 newtons (N) and 0.23 ± 0.09 N, respectively. The CCF at an RVP of 30 mmHg were higher at 3 commissural areas (segments 3, 5 and 8) than at the other segments. The increases in the CCF following changes in the RVP were statistically significant only at the 3 commissural areas (P = 0.012). However, mean CCFs remained low at all annular positions (ranges of average CCF = 0.06–0.46 N). CONCLUSIONS The risk of suture dehiscence after down-sized 3D rigid-ring TAP might be minimal because the absolute forces remained low in all annular positions even in the condition of high RVP. However, careful suturing in the septal annular area and commissures is necessary to prevent an annular tear during a down-sized 3D rigid-ring TAP.

Abstract 16039: Impact of Different Annuloplasty Methods for Tricuspid Regurgitation; a Network Meta-analysis

Background: Although moderate-severe tricuspid valve regurgitation (TR) is an independent risk factor for progressive heart failure and increased mortality, the best method for tricuspid repair remains controversial. As such, we conducted a network meta-analysis to compare early and late outcomes for suture, flexible band, and rigid ring as tricuspid annuloplasty (TAP) in patients with TR. Methods: MEDLINE and EMBASE were searched through February 15th, 2020 to identify randomized controlled trials (RCTs) and observational trials that investigated early and late outcomes after TAP for TR. The outcomes of interest were perioperative mortality, long-term survival and TR recurrence. TR recurrence was defined as at least moderate (TR grade 2) on serial echocardiogram. Results: Our systematic literature search identified 2 RCTs and 16 observational trials, including 6,788 patients who underwent TAP. Median follow-up period was 1-7.4 year. There were no significant differences of perioperative and long-term all-cause mortality among three TAP methods. Suture TAP was associated with a significant increase in TR recurrence compared to rigid ring TAP (Hazard ratio, 2.31; 95% Confidence Interval, 1.40-3.80; p =0.001) (Figure). There were no significant differences were observed in other comparisons in TR recurrence. Conclusion: Our network meta-analysis demonstrated significant reduction in TR recurrence for rigid ring TAP compared to Suture TAP. However, there was no significant mortality difference among suture, flexible band, and rigid ring TAP.

No fibrous cap and pannus formation in an On-X mechanical aortic valve

Mechanical cardiac valves placed in the aortic position can show different amounts of pannus under the aortic ring. A 68-year-old patient had undergone mitral annuloplasty with a 30-mm rigid ring and aortic valve replacement with a 21-mm On-X mechanical valve for mitral regurgitation and aortic valve stenosis 10 years and 3 months previously. In the second cardiac surgery for mitral valve replacement to treat mitral stenosis, the previously replaced On-X mechanical valve revealed no fibrous cap on the sewing cuff and no pannus on the lower border of the valve ring. These characteristic findings can be attributed to the unique design elements of this valve.

On weak (σ, δ)-rigid rings over Noetherian rings

Let R be a Noetherian integral domain which is also an algebra over ℚ (ℚ is the field of rational numbers). Let σ be an endo-morphism of R and δ a σ-derivation of R. We recall that a ring R is a weak (σ, δ)-rigid ring if a(σ(a)+ δ(a)) ∈ N(R) if and only if a ∈ N(R) for a ∈ R (N(R) is the set of nilpotent elements of R). With this we prove that if R is a Noetherian integral domain which is also an algebra over ℚ, σ an automorphism of R and δ a σ-derivation of R such that R is a weak (σ, δ)-rigid ring, then N(R) is completely semiprime.

Understanding structure–property relationships of main chain cyclopropane in linear polyesters

Rigid ring structures have gained increasing interest in the polymer materials community as an effective means to manipulate bulk properties. Here, we investigate structure–property relationships of the smallest ring: cyclopropane.