Faculty Profiles - MUTSUGA Masato

Electrical gaps in recurrence of atrial tachyarrhythmias after Maze surgery: regional patterns and clinical significance

Yano, D; Tokuda, Y; Yasuda, N; Tsurumi, N; Mashiko, Y; Kuwabara, F; Hirate, Y; Tajima, K; Mutsuga, M

NAGOYA JOURNAL OF MEDICAL SCIENCE Vol. 87 ( 1 ) page： 122 - 132 2025.2

Publisher：Nagoya Journal of Medical Science

The Maze procedure is a well-established technique for treating atrial fibrillation; however, atrial tachyarrhythmias can recur postoperatively. This study analyzed the mechanisms of recurrence in patients who underwent electrophysiological studies and catheter ablation following the Maze procedure. Among 88 patients who underwent treatment with a modified Maze procedure, 42 developed recurrent atrial tachyarrhythmias. Among these, 18 underwent electrophysiological studies and simultaneous transcatheter radiofrequency ablation. The median period between the Maze procedure and catheter ablation was 29 months. Macro-reentrant circuits were identified in 12 patients (67%) with or without atrial fibrillation. Most patients (n = 15, 83%) had more than one conduction gap. The most frequently identified gap was around the left inferior pulmonary vein (n = 10, 56%), followed by the peri-coronary sinus area (n = 8, 44%), and the mitral isthmus area (n = 5, 28%). Catheter ablation targeting these gaps successfully eliminated tachyarrhythmias in 15 (83%) patients. At a follow-up examination 49 months after catheter ablation, 14 patients (78%) had no recurrence of tachyarrhythmia. An electrophysiological study revealed conduction gaps in patients with recurrent atrial tachyarrhythmia after the Maze procedure. Modifications to the Maze procedure should include meticulous ablation around the left inferior pulmonary vein orifice, mitral isthmus, and coronary sinus where conduction gaps frequently occur. In cases of recurrence, catheter ablation targeting the lesion effectively controlled the tachyarrhythmia.

DOI： 10.18999/nagjms.87.1.122

Intervening to Preserve Function in Ischemic Cardiomyopathy with a Porous Hydrogel and Extracellular Matrix Composite in a Rat Myocardial Infarction Model Open Access

Merits and Demerits of FET

Mutsuga Masato

Japanese Journal of Cardiovascular Surgery Vol. 54 ( 1 ) page： i - vi 2025.1

Hayashi, Y; Fujii, T; Kim, S; Ozeki, T; Badylak, SF; D'Amore, A; Mutsuga, M; Wagner, WR

ADVANCED HEALTHCARE MATERIALS Vol. 14 ( 2 ) page： e2402757 2025.1

Language：English Publisher：Advanced Healthcare Materials

Multiple hydrogels are developed for injection therapy after myocardial infarction, with some incorporating substances promoting tissue regeneration and others emphasizing mechanical effects. In this study, porosity and extracellular matrix-derived digest (ECM) are incorporated, into a mechanically optimized, thermoresponsive, degradable hydrogel (poly(N-isopropylacrylamide-co-N-vinylpyrrolidone-co-MAPLA)) and evaluate whether this biomaterial injectate can abrogate adverse remodeling in rat ischemic cardiomyopathy. After myocardial infarction, rats are divided into four groups: NP (non-porous hydrogel) without either ECM or porosity, PM (porous hydrogel) from the same synthetic copolymer with mannitol beads as porogens, and PME with porosity and ECM digest added to the synthetic copolymer. PBS injection alone is a control group. Intramyocardial injections occurred 3 days after myocardial infarction followed by serial echocardiography and histological assessments 8 weeks after infarction. Echocardiographic function and neovascularization improved in the PME group compared to the other hydrogels and PBS injection. The PME group also demonstrated improved LV geometry and macrophage polarization (toward M2) compared to PBS, whereas differences are not observed in the NP or PM groups versus control. These results demonstrate further functional improvement may be achieved in hydrogel injection therapy for ischemic cardiomyopathy by incorporating porosity and ECM digest, representing combined mechanical and biological effects.

DOI： 10.1002/adhm.202402757

Impact of direct mesenteric perfusion on malperfusion in acute type A aortic dissection repair

Yamamoto, R; Kato, W; Tokuda, Y; Yamaki, K; Morita, K; Uemura, T; Yamamoto, T; Ito, H; Yoshizumi, T; Terazawa, S; Narita, Y; Mutsuga, M

EUROPEAN JOURNAL OF CARDIO-THORACIC SURGERY Vol. 67 ( 1 ) 2024.12

Language：English Publisher：European Journal of Cardio-thoracic Surgery

OBJECTIVES: Mesenteric malperfusion in acute aortic dissection remains a life-threatening complication with no standardized treatment strategy. This study aimed to describe and evaluate the outcomes of our integrated approach combining exploratory laparotomy, immediate mesenteric reperfusion, and central aortic repair. METHODS: We retrospectively reviewed patients with acute aortic dissection with a preoperative diagnosis of mesenteric malperfusion who were treated between August 2011 and November 2022. Our surgical approach was to establish cardiopulmonary bypass, followed by exploratory laparotomy with mesenteric artery flow assessment using Doppler ultrasound and direct perfusion if needed, central aortic repair, and subsequent mesenteric artery reconstruction. The primary end-point was the 30-day operative mortality. RESULTS: Among 217 patients with acute aortic dissection, 12 (5.5%) had mesenteric malperfusion on preoperative computed tomography. Ten patients underwent exploratory laparotomy, where Doppler ultrasonography revealed reduced mesenteric blood flow in five patients (2.3% of the total 217 patients). These patients underwent direct perfusion of the mesenteric artery via a side branch of the cardiopulmonary bypass circuit. Doppler ultrasound confirmed the restoration of mesenteric blood flow in all perfused patients. No bowel resections were required. The operative mortality in patients with mesenteric malperfusion was 20%. The causes of death were stroke (n = 1) and acute myocardial infarction (n = 1). CONCLUSIONS: Our integrated surgical strategy combining central aortic repair with concurrent exploratory laparotomy and immediate mesenteric perfusion demonstrated technical feasibility in managing mesenteric malperfusion during aortic repair. Further prospective studies with larger cohorts are warranted to validate these findings.

DOI： 10.1093/ejcts/ezae452

Modification of Antibacterial Copolymers on the Surface of PVA-Based Microfibers via Thermal Cross-Linking and Their Antibacterial Properties Open Access

Saito, S; Matsuno, S; Saito, A; Mutsuga, M; Yamawaki-Ogata, A; Narita, Y; Kotsuchibashi, Y

ACS OMEGA Vol. 9 ( 46 ) page： 45961 - 45969 2024.11

Language：English Publisher：ACS Omega

Bacterial infections on material surfaces are a serious public health concern worldwide. Although poly(vinyl alcohol) (PVA)-based materials have great potential as medical devices, they lack antibacterial properties on their surfaces and pose bacterial infection risks during implantation surgery. Copolymers containing antibacterial [2-(methacryloyloxy)ethyl]trimethylammonium chloride (METAC) units were used to modify the surfaces of chemically cross-linked water-insoluble PVA-based microfibers. The copolymers also had carboxy units that were used to react with the hydroxy group of the PVA-based microfibers via a simple thermal treatment at 135 °C. PVA-based materials containing METAC units exhibit significant swelling due to electrostatic repulsions. Because the copolymers were modified on the extreme surface of the microfibers, no difference in the diameters between unmodified microfibers (PM-fiber) and copolymers with METAC unit-modified microfibers (PM-METAC-fiber), in both the dry and swollen states, was observed. The viable bacterial cell numbers, which were evaluated by colony counting, decreased by exposure to the poly(METAC-co-methacrylic acid (MAAc)) aqueous solution or PM-METAC-fibers. The value of CFU/mL decreased to 0.1% (against B. subtilis) and 3.9% (against E. coli) after contact with the PM-METAC-fibers compared to the PM-fibers. The percentage of hemolysis against rabbit red blood cells was equivalent to that of the negative control, suggesting that PM-METAC-fibers can selectively exhibit antibacterial properties. This modification method can be applied to various PVA-based materials if hydroxy groups are present on their surface. This study provides a facile, cost-effective, and promising strategy to impart antibacterial properties to the surface of PVA-based materials without significantly affecting their physicochemical properties.

DOI： 10.1021/acsomega.4c05637

Risk factors for proximal and distal aortic events after type A acute aortic dissection

Akita, S; Tokuda, Y; Kato, W; Tanaka, K; Mutsuga, M

GENERAL THORACIC AND CARDIOVASCULAR SURGERY 2024.9

Language：English Publisher：General Thoracic and Cardiovascular Surgery

Objectives: Type A acute aortic dissection (TAAAD) is a life-threatening condition often requiring emergency surgery, with approximately 30% of patients needing reoperation. This study aimed to identify predictors of long-term aortic events from early postoperative computed tomography (CT) examinations. Methods: A total of 336 cases underwent TAAAD surgery at two institutions between 2002 and 2018. Of these, 302 patients received CT examinations immediately after initial TAAAD surgery. Predictors of aortic events were evaluated from these early postoperative CT exams. Aortic events were defined as any events involving aortic-related death, open surgery, reoperation, endovascular stenting, or thoracic aorta diameter enlargement to ≥ 55 mm. Results: Excluding 34 in-hospital deaths (10.1%; 34/336), the 1-, 5-, and 10-year actuarial survival rates after primary TAAAD surgery were 98.2%, 88.6%, and 81.7%, respectively. Over a mean follow-up period of 7.4 ± 5.1 years, 67 aortic events (proximal: 19, distal: 45, both: 3) were observed. Freedom from proximal aortic events was 98.6%, 93.9%, and 85.2% at 1, 5, and 10 years, respectively. Proximal anastomosis new entry was identified as a significant risk factor for aortic events, with a 92% vs. 42% incidence at 10 years (p < 0.001). Freedom from distal aortic events was 99.6%, 84.5%, and 67.2% at 1, 5, and 10 years, respectively. A false/true area ratio greater than 1 and distal anastomosis new entry were significant risk factors for aortic events (low-risk group: 83.3% vs. high-risk group: 42.3% at 10 years, p < 0.001). Conclusions: Detailed analysis of early postoperative CT scans following primary TAAAD surgery may help identify predictors of subsequent aortic events, potentially improving long-term patient management and outcomes.

DOI： 10.1007/s11748-024-02077-z

HeartMate 3 driveline damage by gradual corrosion due to liquid infiltration: a case report

[How to Insert the Cannula for Central or Peripheral Venous-arterial Extracorporeal Membrane Oxygenation(VA-ECMO)?].

Mutsuga M

Kyobu geka. The Japanese journal of thoracic surgery Vol. 77 ( 10 ) page： 729 - 733 2024.9

Yoshizumi, T; Ito, H; Terazawa, S; Tokuda, Y; Sakurai, H; Narita, Y; Mutsuga, M

JOURNAL OF ARTIFICIAL ORGANS 2024.8

Language：English Publisher：Journal of Artificial Organs

A 31-year-old man with a HeartMate 3 was admitted with a “Driveline Communication Fault” alarm due to liquid infiltration. Eleven months earlier, the connector between the modular and pump cables had gotten wet when he was taking a shower. The cable connector was dried immediately, and no alarm had been observed during follow-up. Subsequently, the modular cable and system controller were replaced, with corrosion found on the modular cable connector. The “Communication Fault” alarm recurred, and complete damage to the communication cables was discovered. The pump was replaced, and the removed pump cable connector showed corrosion as well. If the driveline connector gets wet, the multidisciplinary team should discuss if it should be immediately disconnected and dried, averting the need for future pump replacements due to corrosion.

DOI： 10.1007/s10047-024-01464-w