Yoshifumi Itoda

Paraplegia prevention by oral pretreatment with memantine in a rabbit model

OBJECTIVE To evaluate the role of memantine (N-methyl-d-aspartate receptor antagonist) pretreatment for the prevention of spinal cord ischemia after infrarenal aortic clamping in a rabbit model. METHODS Thirty New Zealand White rabbits were divided into 5 different groups of 6 rabbits. Groups 60-7 and 60-5 received oral memantine 60 mg once a day for 7 and 5 days, respectively, and groups 30-5 and 30-3 received oral memantine 30 mg once a day for 5 and 3 days, respectively, all before surgery. Group C (control) received normal feeds without memantine. A paraplegic model was created by clamping both the aorta and the inferior vena cava infrarenally and just proximal to their bifurcations for 45 minutes. The modified Tarlov score, motor evoked potential (MEP), serum memantine concentration, and histopathology of the spinal cord were evaluated. RESULTS The mean modified Tarlov scores were 4.2±1.3, 4.3±1.0, 4.2±1.3, 4.3±1.2, and 0.8±1.6 in groups 60-7, 60-5, 30-5, 30-3, and C, respectively at 6, 24, 48, and 72 hours (P<.009 for individual groups vs control). Percentage amplitude loss of MEP by the end of surgery was 29.5%±46.3%, 11.9%±28.0%, 30.0%±46.8%, 16.7%±40.8%, and 81.8%±40.3% for the 5 groups, respectively (P=.049). After declamping, MEP reappeared in 83%, 100%, 83%, 83%, and 33% of cases in the 5 groups, respectively (P=.073). The serum memantine level was similar in the 4 memantine groups. Spinal cords were normal in most of the rabbits in groups 60-7, 60-5, 30-5, and 30-3, but severely ischemic in most of the rabbits in group C (P=.041). CONCLUSIONS Oral memantine pretreatment is protective against spinal cord ischemia, and can be an additional strategy for the prevention of paraplegia during thoracoabdominal aortic surgeries.

The Protective Effect of Prone Lung Position on Ischemia-Reperfusion Injury and Lung Function in an Ex Vivo Porcine Lung Model

Objective: Prone positioning has been shown to improve oxygenation in patients with lung injury. We hypothesized that prone positioning of lungs during ex vivo lung perfusion (EVLP) can not only improve oxygenation but also diminish ischemia–reperfusion injury (IRI). The aim of our study was to evaluate the potential benefits of prone positioning of lungs during EVLP compared with the standard supine position. Methods: Ten pigs were kept in the supine position at room temperature for 2 hours after circulatory death after which lungs were procured and subjected to 5 hours of cold storage. Lungs then underwent 2 hours of cellular EVLP with either supine positioning (Control group, n = 5) or prone positioning (Prone group, n = 5). Lung function was evaluated by assessment of physiological parameters and tissue histology and cytokines. Results: IRI in the Prone group was significantly less than in the Control group. Lungs in the Prone group were significantly associated with greater partial pressure of oxygen/fraction of inspired oxygen ratio median (minimum‐maximum) (301 mm Hg [272‐414 mm Hg] vs 166 mm Hg [109‐295] mm Hg, P = .03), better static compliance (38.9 mL/cmH2O [31.1‐44.3 mL/cmH2O] vs 21.5 mL/cmH2O [12.2‐33.3 mL/cmH2O], P = .03), lower lung weight ratio (1.26 [1.24‐1.41] vs 1.48 [1.36‐2.34], P = .02), and lower interleukin‐1&bgr; levels (1.6 ng/mL [0.9‐5.3 ng/mL] vs 7.5 ng/mL [5.0‐16.1 ng/mL], P = .04) compared with lungs in the Control group. Conclusions: These data suggest that prone positioning of lungs during EVLP may diminish IRI during EVLP and improve lung function. Graphical abstract The prone positioning of lungs demonstrated significantly higher P/F ratio, lower lung weight ratio and better lung compliance. Notably, lower lobe demonstrated both less inflammatory cytokine expression and low acute lung injury grade. P/F, Partial pressure of arterial oxygen/fraction of inspired oxygen (PaO2/FiO2). Figure. No caption available.

A successful management of infection of the left ventricular assist device by pump exchange: conversion from DuraHeart to Jarvik 2000

We successfully controlled infection of a left ventricular assist device by performing pump exchange. A 53-year-old man was implanted with DuraHeart for ischemic cardiomyopathy as a bridge to transplantation. Two years later, he was hospitalized with the diagnosis of driveline infection. The blood cultures detected Pseudomonas aeruginosa. During the admission, he developed brain hemorrhage perhaps due to septic emboli. The chest computed tomography scan revealed a small defect inside the outflow graft of the DuraHeart, which was highly suspected of vegetation. He underwent pump exchange, from DuraHeart to Jarvik 2000 with concomitant omentopexy. His postoperative course was uneventful, and he was discharged with no sequela of the brain hemorrhage. Four months after the pump exchange, he successfully underwent heart transplantation. No infectious tissue was observed in the pericardial space at the time of heart transplantation. Pump exchange is an effective way to manage refractory left ventricular assist device infection, and the timing of surgical intervention is of great importance.

Successful management of apical abscess after Nipro left ventricular assisted device explantation by removal of apical cuff and omentopexy

Nipro-Toyobo-paracorporeal pulsatile flow VAD (Nipro VAD; Nipro, Osaka, Japan) has been used most commonly as a paracorporeal VAD (p-VAD) in Japan. There are few reports describing clinical course of post LVAD explantation and its complication. We herein present two cases of apical abscess after the explantation of the device. SSI is a main risk factor of formation of the apical abscess at the time of LVAD explantation. It is mandatory to perform sufficient debridement and closure of the layers including abdominal muscle and anterior abdominal fascia at exit sites in the explantation surgery. Omentopexy is also helpful for prevention from infection. Routine removal of apical cuff and outflow graft could be considered as one of the options when LVAD is explanted as bridge to recovery.

Novel driveline route for prevention from driveline infection: Triple tunnel method

BACKGROUND The most prevalent and serious infection related to left ventricular assist devices (LVADs) is driveline infection (DLI). From 2014, we employed a revised surgical technique (triple tunnel method), which deployed a longer subfascial driveline (DL) route. METHODS AND PATIENTS We retrospectively analyzed 34 patients fitted with either of the two types of axial pumps: HeartMate II (n=23) and Jarvik 2000 (n=11). Prior to 2014, the DL proceeded from the pump pocket just above the posterior sheath of the rectus muscle toward a vertical skin incision at the right lateral border of the rectus muscle. Then, DL was turned leftward into the subcutaneous tissue to redirect its exit to the left side [subcutaneous tissue group (Group S): n=14]. From 2014, we made an additional skin incision below the umbilicus with the aim of lengthening the subfascial DL route [muscle group (Group M): n=20]. RESULTS DLI occurred in 10 patients (71.4%) in Group S and in 1 patient (5%) in Group M (p<0.05, Chi-square test). The freedom rate from re-admission at 1 year due to DLI was 64% in Group S and 95% in Group M, respectively (p=0.021, log-rank test). Furthermore, logistic regression analysis revealed that DL route was significantly associated with DLI (odds ratio, 10.1; 95% confidence interval, 1.15-275.3). CONCLUSION Although a longer follow-up period will be needed, the triple tunnel method may be beneficial in the prevention of DLI.

Single-center experience of the bridge-to-bridge strategy using the Nipro paracorporeal ventricular assist device

Currently, we use the Nipro paracorporeal VAD (p-VAD) for initial short-term ventricular support, as a bridge to decision (BTD) or a bridge to candidacy (BTC) treatment, in Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) levels 1 and 2 patients. However, it is possible that compared to patients with primary implantable-VADs (P-iVAD), the bridge-to-bridge (BTB) patients are more likely to develop complications. This retrospective study used data from 24 consecutive BTB patients who were initially implanted with Nipro p-VAD as BTD or BTC treatments between April 2011 and March 2016, and subsequently underwent conversion to an i-VAD. The data from 72 patients who underwent a primary i-VAD (P-iVAD) procedure were used for comparison. Between the two groups, there was no significant difference in the incidence of infectious events (p = 0.72) or stroke (p = 0.44). Orthotropic heart transplantation was performed in 6 of the 24 patients in the BTB group and in 21 of the 72 patients in the P-iVAD group. The 1- and 2-year survival rates were 95.8% and 95.8% in the BTB group and 91% and 85.8% in the P-iVAD group; these values were not significantly different between groups (p = 0.91). Based on these results we conclude that BTB using Nipro p-VAD is a reasonable strategy for treating patients with severe decompensated end-stage heart failure.

Implantation of a Left Ventricular Assist Device for Danon Cardiomyopathy

This is the first report of Danon cardiomyopathy managed with a left ventricular assist device (LVAD). Danon disease is an X-linked dominant inheritance disorder. Heart failure with Danon cardiomyopathy results in a poor prognosis, and heart transplantation is the treatment of choice. We present two cases of successful implantation of an LVAD for Danon cardiomyopathy. Patient 1 was in the dilatated phase of hypertrophic cardiomyopathy (HCM) with Danon cardiomyopathy, and she underwent LVAD implantation. She is waiting for transplantation. Patient 2 had dilatated cardiomyopathy with Danon cardiomyopathy and received transplantation 990 days after LVAD implantation without myopathy or intellectual disability.

A New Suturing Device for Small Arteries

Endoscope-assisted surgery and robot-assisted surgery are not common in cardiac surgery, particularly coronary artery bypass grafting, because of the complex nature of the procedures. We developed a new suturing device that allows for easy performance of such cardiac surgeries in comparison with conventional suturing methods. A total of 63 rabbits were used in this study. The right carotid artery was bypassed using the same side of the jugular vein under endoscopic guidance. Of these, 48 rabbits were operated on using the new devices and 15 rabbits were operated on using conventional polypropylene sutures. The proximal suturing time was 16.6 ± 5.3 minutes in the group that underwent surgery using the new device (group D) and 22.8 ± 7.6 minutes in the control group (group C; P < 0.05). The distal suture time was 16.3 ± 4.2 minutes in group D and 22.8 ± 6.0 minutes in group C (P < 0.05). The operation time was 113.0 ± 15.8 minutes in group D and 136.7 ± 20.6 minutes in group C (P < 0.05). Graft flow was 19.9 ± 12.8 mL/minute in group D and 12.1 ± 11.3 mL/minute in group C (P < 0.05). Thus, the operation time and the suture time differed significantly between the groups. This device provides advantages in endoscopic surgery compared to the conventional suture method.