Tadaaki Koyama

Gelatin sheet incorporating basic fibroblast growth factor enhances sternal healing after harvesting bilateral internal thoracic arteries

OBJECTIVEnWe previously reported that a gelatin sheet incorporating basic fibroblast growth factor accelerated sternal healing after bilateral internal thoracic artery removal in normal and diabetic rats. The aim of this study was to evaluate the effects of this therapeutic modality on sternal healing in a large-animal model before performing a clinical trial.nnnMETHODSnAfter median sternotomy and bilateral internal thoracic artery removal in a pedicled fashion, 14 beagle dogs received either a gelatin sheet incorporating basic fibroblast growth factor (100 mug per sheet) on the posterior table of the sternum (FGF group, n = 7) or did not receive a gelatin sheet (control, n = 7). We compared sternal healing 4 weeks after surgical intervention between the groups.nnnRESULTSnScintigraphic images obtained by using technetium 99 methylene diphosphonate bone scanning were assessed visually, and the impulse rate was quantified 30 and 60 minutes after injection of technetium 99 methylene diphosphonate to evaluate the sternal perfusion. Sternal uptake was significantly increased in the FGF group (30 minutes: 221% +/- 30% vs 180% +/- 36%; 60 minutes: 267% +/- 26% vs 197% +/- 42%; P <.01). Apparent sternal dehiscence, as assessed radiographically, was observed only in the control animals. Histologically, complete healing of the sternum with marked angiogenesis was observed in the FGF group, whereas poor healing with limited angiogenesis was seen in the control animals. Both bone mineral content (134 +/- 49 vs 52 +/- 32 mg, P <.01) and bone mineral density (133 +/- 53 vs 66 +/- 32 mg/mm(2), P <.05) along the incision line of the sternum, as assessed by means of dual-energy x-ray absorptometry, were higher in the FGF group.nnnCONCLUSIONSnA gelatin sheet incorporating basic fibroblast growth factor enhances sternal perfusion and accelerates sternal bone healing in large animals.23

Attenuation of adhesion formation after cardiac surgery with a chymase inhibitor in a hamster model

OBJECTIVEnChymase is one of the inflammatory mediators and is released from mast cells, which are closely associated with adhesion formation. Chymase also activates transforming growth factor beta1, which promotes tissue fibrosis. However, the role of chymase in cardiac adhesion formation has not yet been elucidated. We have assessed whether a specific chymase inhibitor, Suc-Val-Pro-Phe(p) (OPh)(2), prevents postoperative cardiac adhesions in hamsters.nnnMETHODSnIn 66 hamsters the epicardium was abraded, and then either chymase inhibitor or placebo was injected into the left thoracic cavity, leaving the pericardium open. Cardiac chymase activity, the level of transforming growth factor beta1 in the pleural fluid, and the density of epicardial mast cells were measured 3 days postoperatively. The degree of adhesion formation was evaluated macroscopically and histologically 2 weeks postoperatively by using a grading score ranging from 0 (no adhesions) to 4 (severe adhesions).nnnRESULTSnThe cardiac chymase activity and level of transforming growth factor beta1 were lower in the chymase inhibitor-treated group compared with in the placebo-treated group (45.8 +/- 18.7 vs 79.7 +/- 13.7 microU/mg protein [P <.025] and 15.6 +/- 6.5 vs 33.2 +/- 9.8 microg/mL [P <.01], respectively). The density of mast cells was higher in the placebo-treated group, and there was suppression to 60% of this value in the chymase inhibitor-treated group. The adhesion scores were lower in the chymase inhibitor-treated group compared with in the placebo-treated group (1.3 +/- 1.3 vs 3.0 +/- 1.1, P <.01).nnnCONCLUSIONnUse of a chymase inhibitor suppresses not only cardiac chymase activity but also the level of transforming growth factor beta1, and this results in a reduction in postoperative cardiac adhesion.

Attenuating Effects of Chymase Inhibitor on Pericardial Adhesion Following Cardiac Surgery

Abstractu2003 Objective: Chymase, a serine protease, is released from mast cells, which is closely associated with adhesion formation. Chymase activates transforming growth factor‐β1 (TGF‐β1), which promotes tissue fibrosis. Recently we have found that chymase may play an important role in adhesion formation in hamsters. Accordingly, this study was designed to confirm that a chymase inhibitor prevents postoperative cardiac adhesions in large animals. Methods: In 14 dogs, the epicardium was abraded 200 times with gauze and the mid‐portion of the left anterior descending coronary artery (LAD) was exposed with No. 15 blade. Either chymase inhibitor (CI group, n = 7) or placebo (P group, n = 7) was sprayed into the pericardial cavity, then the pericardium was closed. Cardiac chymase activity, the level of TGF‐β1 in the pericardial fluid, the density of epicardial mast cells, the adhesion area between the heart and the pericardium, and the presence of adhesion between the mid‐LAD and the pericardium were evaluated 1 and 2 months after surgery. Five nonsurgical dogs were used as a control for cardiac chymase activity. Results: Cardiac chymase activity and TGF‐β1 level were lower in CI group than in P group (53.7 ± 35.0 vs. 93.4 ± 20.4 μU/mg protein, p = 0.01, 3.2 ± 0.9 vs. 4.3 ± 1.1 μg/mL, p = 0.06, respectively). In CI group, the density of mast cells (19 ± 5 vs. 32 ± 8 cells/cm, p < 0.01), the adhesion area (2.2 ± 0.8 vs. 7.5 ± 1.5 cm2, p < 0.01), and adhesions between the heart and the mid‐LAD (0% vs. 57%) were all reduced. Conclusion: Chymase inhibitor suppresses cardiac chymase activity and reduces the TGF‐β1 level, resulting in a reduction of cardiac adhesion in a large animal.

Early and mid-term results of left ventricular volume reduction surgery for dilated cardiomyopathy

Abstractu2002 Objective: To evaluate structure‐oriented left ventricular volume reduction surgery (LVVRS). The purpose of this study was to report the early and mid‐term results of left volume reduction surgery for dilated cardiomyopathy (DCM). Methods: We performed LVVRS on 29 patients with DCM. The age of the patient ranged from 8 to 73 years (mean 58 ± 18 years). There were 19 male patients (63%). Twenty‐three patients were ischemic, 5 were non‐ischemic, and 1 had salcoidosis. Twenty‐three patients were in New York Heart Association class III or IV. Fourteen patients underwent the Dor operation, 11 underwent a septal anterior ventricular exclusion operation, and 6 underwent a modified Batista operation. Fifteen patients underwent mitral annuloplasty and 2 patients had mitral valve replacement. All patients were divided into two groups, a Dor group (n = 14) and non‐Dor group (n = 15). Postoperative early results and mid‐term survival rate were compared between the two groups. Results: Hospital mortality was 13.8% (4/29). The causes of death were low‐output syndrome (n = 3) and septic shock (n = 1). Survival rate was 80% at 1 year and 72% at 3 years. Two‐year survival rate of Dor and non‐Dor groups were 69.8% and 93.8%, respectively (p = 0.099). Conclusions: Early and mid‐term results of LVVRS were satisfied, and the non‐Dor operation tended to be superior in mid‐term survival to the Dor operation. Long‐term follow‐up is warranted.

Development of a Training System for Cardiac Muscle Palpation

Touching the cardiac muscle is necessary to get mechanical conditions of muscle before cardiac surgery. The cardiac palpation is the only way to make surgical plans for left ventricular plastic surgery. The training system for cardiac palpation we have developed consists of a MRI-based virtual left ventricular image and a one-dimensional manipulator as a haptic device. Mechanical properties of the cardiac muscles of a dog and a pig are embedded in the virtual heart. Our experiments show that the developed training system enables users to feel the reactional force to the virtual heart surface from the manipulator in real time.

Asymptomatic traumatic diaphragmatic hernia discovered during an aortic valve replacement.

Asymptomatic traumatic diaphragmatic hernia, which presents in an adult, is an extremely rare entity. We discuss the management of a 63‐year‐old male with an asymptomatic traumatic diaphragmatic hernia discovered during aortic valve replacement. doi: 10.1111/jocs.12341 (J Card Surg 2014;29:473–475)

Toward an Ideal Large Animal Model of Dilated Cardiomyopathy to Study Left Ventricular Volume Reduction Surgery

The Batista operation for dilated cardiomyopathy (DCM) has not, thus far, yielded satisfactory results. One of the explanations for disappointing results is the absence of a suitable animal model of dilated cardiomyopathy. Scientific research on volume reduction surgery needs to be carried out in an appropriate experimental model. This chapter reviews the few studies of volume reduction surgery using animal models of DCM published thus far, including our studies.