Takenori Yokota

University of Pittsburgh, Pittsburgh, Pennsylvania, United States

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Publications (8)28.63 Total impact

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    ABSTRACT: OBJECTIVE: Single-port subxiphoid videopericardioscopy with a rigid shaft is useful for left atrial exclusion, left ventricular pacing lead implantation, and epicardial mapping, but it may interfere with the cardiac rhythm and adversely alter hemodynamics. We examined the impact of this technique on hemodynamic indices in a porcine model. METHODS: The videopericardioscopy device was introduced into the pericardial space of 5 pigs (35-45 kg) via a subxiphoid approach and navigated to 6 anatomical targets (right atrial appendage, superior vena cava, ascending aorta, left atrial appendage (anterior and posterior approaches), transverse sinus, and atrioventricular groove). After successful target acquisition, the device was withdrawn through the subxiphoid port. When the hemodynamics stabilized, the device was navigated to another target. The heart rate, arterial blood pressure, central venous pressure, pulmonary arterial pressure, and mixed venous oxygen saturation were measured at every pre-target (subxiphoid incision) and target point. After the navigation trials, the animals were sacrificed and the mediastinum space was examined for procedure-related injuries. RESULTS: The device afforded a good view, and the navigation trials were successfully performed on the beating heart. Four animals tolerated the procedures, while 1 died of device-induced ventricular fibrillation after the trials. Hemodynamics were severely compromised at all anatomical targets except the left atrial appendage (anterior approach). CONCLUSIONS: Subxiphoid videopericardioscopy significantly interferes with the cardiac rhythm, causing life-threatening arrhythmia and hemodynamic compromise, when the target is located deep and far from the pericardiotomy. A flexible or highly articulated device would enable intrapericardial navigation without hemodynamic compromise.
    Innovations Technology and Techniques in Cardiothoracic and Vascular Surgery 01/2010; 5(1):51-54.
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    ABSTRACT: We have developed a tissue-engineered patch for cardiovascular repair. Tissue-engineered patches facilitated site-specific in situ recellularization and required no pretreatment with cell seeding. This study evaluated the patches implanted into canine pulmonary arteries. Tissue-engineered patches are biodegradable sheets woven with double-layer fibers. The fiber is composed of polyglycolic acid and poly-L-lactic acid, and compounding collagen microsponges. The patches (20- x 25-mm) were implanted into the canine pulmonary arterial trunks. At 1, 2, and 6 months after implantation (n = 4), they were explanted and characterized by histologic and biochemical analyses. Commercially available patches served as the control. No anticoagulant therapy was administered postoperatively. No aneurysm or thrombus was present within the patch area in all groups. The remodeled tissue predominantly consisted of elastic and collagen fibers, and the endoluminal surface was covered with a monolayer of endothelial cells and multilayers of smooth muscle cells beneath the endothelial layer. The elastic and collagen fibers and smooth muscle cells kept increasing with a maximum at 6 months, while a monolayer of endothelial cells was preserved. The expression levels of messenger RNA of several growth factors in the tissue-engineered patches were higher than those of native tissue at 1 and 2 months and decreased to normal level at 6 months. No regenerated tissue was found on the endoluminal surface in the control group. The novel tissue-engineered patches showed in situ repopulation of host cells without prior ex vivo cell seeding. This is promising material for repair of the cardiovascular system.
    The Annals of thoracic surgery 10/2009; 88(4):1269-76. · 3.45 Impact Factor
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    ABSTRACT: Although a septal-superior approach provides excellent exposure of the mitral valve, it requires novel strategies for concomitant ablation in patients with atrial fibrillation. Utilizing a combination of bipolar radiofrequency and cryothermy, we developed a novel technique for creating a biatrial lesion set via a septal-superior approach during mitral valve surgery. We treated 10 patients with functional mitral regurgitation and permanent atrial fibrillation with rhythm disturbance for a mean 87 months. A modified maze was successfully accomplished via a septal-superior approach in all. The mean follow-up period was 18 months, during which permanent pacemaker implantation was necessary for one due to sinus bradycardia. Sustained sinus rhythm, including atrial or atrial-based paced rhythm, was present in all immediately after surgery, in 70% at discharge, in 80% at 1 year after surgery, and in 90% at the latest follow-up examination. Our novel technique using a modified maze procedure in combination with mitral valve surgery via a septal-superior approach was safe and useful for eliminating atrial fibrillation, with a relatively low frequency of sinus node dysfunction.
    European journal of cardio-thoracic surgery: official journal of the European Association for Cardio-thoracic Surgery 05/2009; 36(1):198-9. · 2.40 Impact Factor
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    ABSTRACT: Various types of natural and synthetic scaffolds with arterial tissue cells or differentiated stem cells have recently attracted interest as potential small-caliber vascular grafts. It was thought that the synthetic graft with the potential to promote autologous tissue regeneration without any seeding would be more practical than a seeded graft. In this study, we investigated in situ tissue regeneration in small-diameter arteries using a novel tissue-engineered biodegradable vascular graft that did not require ex vivo cell seeding. Small-caliber vascular grafts (4 mm in diameter) were fabricated by compounding a collagen microsponge with a biodegradable woven polymer tube that was constructed in a plain weave pattern with a double layer of polyglycolic acid (core) and poly-L-lactic acid (sheath) fibers. We implanted these tissue-engineered vascular grafts bilaterally into the carotid arteries of mongrel dogs (body weight, 20-25 kg). No anticoagulation regimen was used after implantation. We sacrificed the dogs 2, 4, 6, and 12 months (n = 4 in each group) after implantation and evaluated the explants histologically and biochemically. All of the tissue-engineered vascular grafts were patent with no signs of thrombosis or aneurysm at any time. Histologic and biochemical examinations showed excellent in situ tissue regeneration with an endothelial cell monolayer, smooth muscle cells, and a reconstructed vessel wall with elastin and collagen fibers. Our study indicated that this novel tissue-engineered vascular graft promoted in situ tissue regeneration and did not require ex vivo cell seeding, thereby conferring better patency on small-caliber vascular prostheses.
    The Journal of thoracic and cardiovascular surgery 11/2008; 136(4):900-7. · 3.41 Impact Factor
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    ABSTRACT: We developed a simple and secure technique for reimplantation of the intercostal arteries (ICAs) using a patch graft during thoracoabdominal aneurysm repair. With our procedure, a sidearm branch with its base is tailored from a 24 mm one-branch Dacron graft, and then sutured as a patch graft to the trimmed wall of the descending aorta to cover the ICA orifices between Th9 and Th12. The proximal end of the patch graft is then anastomosed to the main tube graft, while the graft is perfused. With this technique, the entire suture lines are clearly visible and hemostasis is secured without difficulty. We used this technique in 6 patients, in whom 2.3+/-0.8 pairs of ICAs were reimplanted. The time required for reimplantation of the ICAs was 14+/-6 min and none of 6 patients developed paraplegia. Our results indicate that this novel technique is a simple method to obtain secure hemostasis under direct vision, which may contribute to reduce the risk of paraplegia during thoracoabdominal aneurysm repair.
    European Journal of Cardio-Thoracic Surgery 08/2008; 34(2):458-9. · 2.67 Impact Factor
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    ABSTRACT: We treated a patient with gastric cancer considered to be unresectable due to peritoneal metastasis, who responded remarkably to treatment with TS-1. The patient was a 62-year-old male. His diagnosis was gastric cancer, for which he underwent surgery on February 22, 2001. Laparotomy disclosed many nodules measuring 2-3 mm in diameter in the abdominal cavity, so rapid pathological tests were conducted during the operation. The test results indicated peritoneal metastasis from gastric cancer. Therefore, simple laparotomy was employed as the best option. On day 13 after surgery, oral administration of TS-1, bid., at a daily dose of 120 mg was commenced. In our outpatient clinic, he was given 3 courses, each comprising 4 weeks' medication and 2 weeks' discontinuation. Subsequently, upper digestive tract endoscopy was performed but only scars in the gastric vestibular area were observed. Biopsy could not detect any malignant findings. Medication was discontinued due to the patient's preference and he died of gastric cancer 10 months after operation.
    Gan to kagaku ryoho. Cancer & chemotherapy 07/2003; 30(6):855-8.
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    ABSTRACT: Although a staged elephant trunk procedure has been widely used, the early mortality of the first stage operation as well as the interval mortality between operations remains unsatisfactory. We developed an alternative elephant trunk procedure to reduce mortality and morbidity. Ascending aorta and arch vessels were minimally dissected. During systemic cooling, a four-branched arch graft with a sewing "collar" and a long "elephant trunk" was prepared. The ascending aorta was opened under selective brain perfusion with moderate hypothermia (25 degrees C), and the elephant trunk was then pulled down into the descending aorta using the catching catheter introduced via a femoral artery. The elephant trunk anastomosis using the collar was made at the base of the innominate artery. The arch vessels were divided and closed at aortic stump, and grafted separately as a consequence of the very proximal site for the elephant trunk anastomosis. Between October 1998 and September 2001, 17 patients, ranging in age from 25 to 79 years (mean 67 years) with extensive aortic aneurysm underwent this operation. Preoperative cardiac complications included coronary artery disease in 5, aortic regurgitation in 3, and 3 of these 8 patients had poor left ventricular function with an ejection fraction less than 40%. Nine patients underwent a second stage operation, in 1 of them the permanent elephant trunk procedure was initially attempted but the second stage procedure was done because of increasing endo-leakage. The mean interval between operations was 8 days (range 1 to 14 days) in the remaining 8 patients. In 5 of 6 patients who underwent the permanent elephant trunk procedure, a decrease in the size of the aneurysm based on thromboexclusion was observed using serial computed tomography scans. A single stage repair was performed in 1 patient. The 30-day survival rate of all operations was 100%, however, there was 1 in-hospital death (6%) after the second operation. There was no stroke, however, paraplegia occurred after the first operation in 1 patient (6%) of the in-hospital death. No new phrenic or recurrent laryngeal nerve palsy occurred as a result of surgery. The present technique using a modification of the elephant trunk technique for extensive aortic aneurysm provides acceptable mortality and morbidity. The present strategy would be an alternative for the standard elephant trunk procedure in some high-risk patients with advanced age and comorbidities.
    Circulation 10/2002; 106(12 Suppl 1):I253-8. · 15.20 Impact Factor
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    ABSTRACT: Although gastric mucosal tonometry has been reported as a useful method to assess splanchnic perfusion during cardiovascular surgery, the conventional discontinuous method of tonometry (saline tonometry) was cumbersome and prone to systematic errors. A new automated system of air tonometry (Tonocap; Datex Ohmeda, Helsinki, Finland) allows for frequent (every 10 minutes) measurement of gastric regional CO2 (PrCO2) and may be more suitable as a monitoring system in cardiac patients. We evaluated the usefulness of continuous air tonometry as a marker of splanchnic perfusion during cardiopulmonary bypass (CPB). In 19 patients (53-79 years, mean 63 years) who underwent cardiovascular surgery under standard CPB with mild hypothermia (32 degrees C) from January 2001 to May 2002, the PrCO2 and calculated intramucosal pH (pHi) of gastric tonometry was monitored using Tonocap, and their relation to postoperative visceral organ function was evaluated. The pHi significantly increased after initiation of CPB from 7.32 +/- 0.07 to 7.43 +/- 0.10 (p < 0.05) and then consistently decreased in all patients to 7.39 +/- 0.09 at the end of CPB. The value of PrCO2 significantly (p < 0.01) correlated with the value of pHi. The lowest value of pHi during CPB was significantly related to blood urea nitrogen (r = -0.75, p < 0.05), serum creatinine (r = -0.78, p < 0.05), creatinine clearance (r = 0.68, p < 0.05) on postoperative day 1, and blood urea nitrogen (r = -0.84, p < 0.01) on day 3. In contrast, arterial blood lactate level, venous oxygen saturation, and routinely measured hemodynamics (e.g., pump flow, arterial pressure) during CPB were unrelated to the postoperative visceral organ function. These results suggest that continuous monitoring of gastric regional CO2 and pHi by air tonometry system is useful for the evaluation of splanchnic perfusion during CPB and may contribute to improve CPB technique by allowing the early detection of visceral malperfusion.
    ASAIO Journal 01/2002; 49(1):108-11. · 1.49 Impact Factor

Publication Stats

56 Citations
28.63 Total Impact Points

Institutions

  • 2010
    • University of Pittsburgh
      Pittsburgh, Pennsylvania, United States
  • 2008–2009
    • Osaka City University
      • Department of Cardiovascular Surgery
      Ōsaka, Ōsaka, Japan
    • Osaka Rosai Hospital
      Ōsaka, Ōsaka, Japan