高木 靖

OBJECTIVE: To investigate the impact of the discrepancy between the predicted annuloplasty ring size determined by preoperative transesophageal echocardiography and the actual ring size on the outcomes of mitral valve repair (MVr) using primarily the loop technique. METHODS: Among 370 patients who underwent MVr between January 2008 and December 2024, 154 who underwent MVr with the semirigid ring for degenerative disease were involved in this study. Ring size was estimated according to the lengths of A2 and P2 by transesophageal echocardiography. Patients were classified into 3 groups-small, match, and large-based on the discrepancy between the predicted and actual ring sizes. RESULTS: Compared with the other small and match groups, patients in the large group had shorter anterior leaflet length (P = .03), smaller posterior leaflet angle (P = .01) and smaller coaptation depth (P = .03) in the coaptation triangle. There was no significant difference in coaptation length among the 3 groups. The cumulative incidence of mitral regurgitation (MR) grade ≥2 was 0.6% at 1 year, 5% at 5 years, and 24% at 10 years, whereas that of a mean transmitral pressure gradient ≥5 mm Hg were 5%, 13%, and 16%, respectively. Fine-Grey multivariable analysis identified larger posterior leaflet angle after repair as a risk factor for recurrence of MR grade ≥2 and larger body surface area, smaller prosthesis size, and shorter coaptation length as risk factors for functional mitral stenosis. CONCLUSIONS: Size mismatch of the prosthesis ring did not change the coaptation length, late MR recurrence, or functional mitral stenosis after MVr.

Heparin resistance (HR) is observed before cardiopulmonary bypass (CPB), despite with normal antithrombin III (AT-III) levels. The relationships between preoperative AT-III activity and activated clotting time (ACT) after the first heparin dose should be clarified. We retrospectively analyzed the data of 818 patients who underwent CPB surgery, with the initial heparin of 300, 400, and 500 IU/kg, between 2017 and 2021. We defined HR as the failure to achieve ACT after the initial heparin dose (Post ACT) of > 480 s.There were no significant correlations between the AT-III activity and Post ACT in all patients, including 143 patients with AT-III activity < 80% and 675 patients with AT-III activity of ≥ 80%. Also, there were no significant correlations between the AT-III activity and Post ACT in 74 patients who received heparin of 300 IU/kg, in 186 patients with 400 IU/kg, and in 339 patients with 500 IU/kg. After identifying smoking, HR, activated partial thromboplastin time, fibrinogen degradation products (FDP), and ACT as influencing factors, multiple comparisons using the Steel-Dwass test showed significant difference in FDP and HR among the patients who received heparin of 300 IU/kg, 400 IU/kg, and 500 IU/kg. There is no association between preoperative AT-III activity and ACT after the first heparin administration for CPB, even in different dose of heparin. Rather, the higher the initial UFH dose is, the higher ACT may be, regardless of the AT-III activity.

BACKGROUNDS: One of the strategies to prevent stroke after coronary artery bypass grafting (CABG) may be the use of a device for proximal anastomosis without partial clamp of the ascending aorta. METHODS: We retrospectively investigated early and late outcomes in consecutive 881 patients undergoing isolated CABG using Heartstring for proximal anastomosis from January 2008 to December 2022, to reveal the validity to use it. All patients underwent preoperative imaging workups to evaluate neurovascular atherosclerosis. RESULTS: The mean age of the patients was 68.9 years, 20% were female and 13% had previous history of stroke. CABG was on-pump beating heart (52.2%) or off-pump (47.8%) with a mean number of distal anastomoses of 3.38 ± 0.93, using 1.62 ± 0.53 Heartstring devices under different aortic manipulations. In-hospital mortality was 2.0% and perioperative stroke rate was 0.9%, none of them died during hospital stay. During the follow-up period of 70 ± 47 months, the overall actuarial survival rates were 86 and 66%, and major adverse cardiac and cerebrovascular events (MACCEs)-free rates were 86 and 70% at 5 and 10 years, respectively. On multivariable analysis, risk factors for late death included male, previous history of stroke, postoperative sternomediastinitis, late new-onset stroke, and MACCEs, but did not include the perioperative stroke. CONCLUSION: Low stroke rate, as low as 0.9%, after CABG using Heartstring for proximal anastomosis, although under a variety of aortic manipulations, may contribute to the improved long-term prognosis.

Fractional flow reserve (FFR) has been well validated as a modality for evaluating myocardial ischemia, demonstrating the superiority of FFR-guided percutaneous coronary intervention (PCI) over conventional angiography-guided PCI. As a result, the strategy for coronary artery bypass grafting (CABG) is shifting toward FFR guidance. However, the advantage of FFR-guided CABG over angiography-guided CABG remains unclear. While FFR-guided CABG can help avoid unnecessary grafting in cases of moderate stenosis, it may also carry the risk of incomplete revascularization. The limited use of FFR due to the need for hyperemia has led to the development of non-hyperemic pressure ratios (NHPRs). NHPR pullback provides trans-stenotic pressure gradients, which may offer valuable insights for CABG strategies. Recently, computed tomographic coronary angiography (CTCA) has emerged as a non-invasive modality that provides accurate data on lesion length, diameter, minimum lumen area, percentage stenosis, and the volume and distribution of high-risk plaques. With the introduction of FFR-CT, CTCA is now highly anticipated to provide both functional evaluation (of myocardial ischemia) via FFR-CT and anatomical information through serial quantitative assessment. Beyond the diagnostic phase, CTCA, augmented by automatic artificial intelligence, holds great potential for guiding therapeutic interventions in the future.

As the current guidelines on myocardial revascularization recommend, transit-time flow measurement (TTFM) is increasingly used for intraoperative graft flow analysis during coronary artery bypass grafting (CABG) as a less invasive, more highly reproducible, and less time-consuming method. In addition to the morphological assessment using color Doppler, mean graft flow (Qm) > 15 ml/min, pulsatility index (PI) < 5.0, diastolic filling (DF) > 50%, and systolic reverse flow (SRF) < 4% have been reported to predict patent CABG grafts. However, it is difficult to determine the clear-cut cut-off value of these parameters, because they varies with the hemodynamic characters, including fractional flow reserve (FFR) of the target coronary artery. In addition to these parameters, we focused on fast Fourier transform (FFT) analysis, because the TTFM waveform morphology may be more important than Qm itself. FFT analysis is based on the principle that any periodic waveforms can be broken down into a series of pure sine waves or harmonics. Herein we review FFT analysis of the intraoperative TTFM waveforms for quality assessment of CABG grafts.