Biomedical subjects

Masaaki Toyama

Publications and source records attributed to Masaaki Toyama.

5 recordsLinked to original sources

PubMed2004

Oxygen pressure measurement during grip exercise reveals exercise intolerance after radial harvest.

BACKGROUND: Exercise intolerance of the hand after harvest of the radial artery is not well understood, although mild reductions of blood flow to the hand are reported. To ascertain its prevalence, patient symptoms implying potential exercise intolerance were evaluated by measuring transcutaneous oxygen pressure of the hand during grip exercise. For ascertaining predictive values, we verified ulnar flow reserve measured by Doppler ultrasonography before the harvest of radial artery. METHODS: Forty patients whose radial artery was harvested for coronary bypass graft, were interviewed and tested 1 year after operation, and their preoperative ultrasonographic data compared. RESULTS: Five patients (12.5%) had mild symptoms implying exercise intolerance. Exercise tests revealed severe decreases in tissue oxygenation in 7 patients (17.5%), but in accordance with symptoms (p = 0.0018). Tissue oxygenation in the operated hand was lower than in the nonoperated even in asymptomatic patients (p = 0.0011). Preoperative Doppler echography revealed that ulnar arteries of symptomatic patients were smaller (p = 0.0019) and carried lower blood flows during manual compression of the radial artery (p = 0.0004) compared with those of asymptomatic patients. Smaller ulnar arteries (less than 1.4 mm/m(2)) with poor flow reserves (less than 60 mL x min(-1) x m(-2) during radial compression) appear to indicate risks for exercise intolerance (p = 0.0004). CONCLUSIONS: More than 10% of patients after harvest of radial arteries had mild symptoms implying exercise-intolerance, which accorded with abnormal tissue oxygenation during grip exercise. Work habits of patients should be considered in radial harvest decisions, especially if preoperative Doppler echography indicates lower flow reserves for the ulnar artery.

Blood Flow Velocity↗

PubMed2004

Double-patch technique for postinfarction ventricular septal perforation.

A modified infarct-exclusion technique for postinfarction ventricular septal perforation is presented. The perforation is closed directly by a small patch next to the conventional patch, and biological glue is applied between the patches to induce stable polymerization. The patch stuck to the infarcted septum, and no residual shunt was observed in any patient because the wide adhesion prevents excessive pressure on the suture line. Seven of 9 patients in whom this method was used had good results. This technique appears suited for repair of ventricular septal perforations, especially those with extensive fresh infarction.

Cardiac Surgical Procedures↗

PubMed2003

Transaortic stented graft implantation for aortic arch aneurysm. Its benefits and risk.

OBJECTIVES: Despite steady improvements, surgery for aortic arch disease, including the distal arch, continues to result in high rates of morbidity and mortality. We have performed aortic arch repair using a transaortic stented graft implantation into the descending aorta in 8 patients who had true aortic arch aneurysms, and here have reviewed the efficacy and problems from this procedure. METHODS: Six patients underwent transaortic stented graft implantation into the descending aorta with bypass to the arch vessels. The other two underwent stented graft implantation into the descending aorta with replacement of the ascending aorta and aortic arch. One patient had a ruptured aneurysm. RESULTS: Each operation was performed via a median sternotomy without left thoracotomy. There was no new postoperative occurrence of left recurrent laryngeal nerve palsy. All the five patients without perioperative neurological complication could be extubated within 24 h after surgery. In each case, postoperative enhanced computed tomography scans showed successful thromboexclusion of the aneurysm. There was no endoleak and no graft migration. One patient suffered cerebral injury. Spinal cord injury occurred in 2 patients, and this serious complication may have been caused by prolonged ischemia in the lower body and the long stented graft. CONCLUSIONS: This surgical strategy was effective for arch aneurysm and produced less damage than a conventional procedure to the postoperative respiratory function, while the operative technique need to be improved to decrease the frequency of brain and spinal cord injury.

Aged↗

PubMed2002

Stented elephant trunk procedure combined with ascending aorta and arch replacement for acute type A aortic dissection.

OBJECTIVES: Despite steadily improving outcomes, surgery for acute type A aortic dissection has several unresolved problems such as expansion of the residual false lumen in the descending aorta. We performed transaortic stented graft implantation into the descending aorta combined with the ascending aorta and aortic arch replacement for acute type A aortic dissection. We review the efficacy and outcomes of this procedure with respect to the residual false lumen and postoperative neurologic complications we encountered. METHODS: Nine consecutive patients with acute type A aortic dissection underwent this procedure. The stented elephant trunk graft was implanted through the aortic arch under hypothermic circulatory arrest. The stented graft was 15 cm long in six patients, and 10 cm long in three patients. Enhanced computed tomography (CT) was performed 1 month after surgery and once each year after discharge to evaluate the postoperative time course of the residual false lumen. RESULTS: Cardiopulmonary bypass (CPB) time was quite long because of slow cooling and re-warming [352+/-92 (mean+/-SD) min], and average lower-body arrest time was 54+/-10min. The intima in one patient was injured at the time of implantation, and a small leak was created. One patient died of multiorgan failure postoperatively. One patient suffered cerebral injury, and two suffered spinal cord injury perioperatively. Average follow-up time was 40.4 months (range, 13-66 months). One patient died of cerebral infarction during follow up, and the other seven survived and remain well. Postoperative enhanced CT scans showed that the dissected descending aortas attached to the stented grafts and the aortas near the stented grafts returned to normal. In one patient with no re-entry, the false lumen completely closed with thrombi and the entire aorta returned to normal. The diameter of the descending aorta decreased or did not change in six of the seven patients (85.8%) and increased by only 2mm in one of them (14.2%) during follow up. CONCLUSIONS: Implantation of a stented elephant trunk into the descending aorta combined with replacement of the ascending aorta and total arch for acute type A aortic dissection is effective in closing the residual false lumen of the descending aorta and in preventing expansion of the descending aorta. However, further technical modifications, such as using a short stented elephant trunk, eliminating aortic clamping, shortening CPB and spinal cord ischemic time, and reconstruction of left subclavian artery, are needed to prevent neurologic complications.

Acute Disease↗

PubMed2002

Vocal cord paralysis after surgery for thoracic aortic aneurysm.

OBJECTIVE: To determine the incidence, etiology, prognosis, and treatment of vocal cord paralysis (VCP) after surgery for thoracic aortic aneurysm (TAA). STUDY DESIGN: Retrospective study performed between 1989 and 1995. SETTING: Academic, tertiary care, referral medical center. PATIENTS: Seventy-one TAA patients underwent surgery at the Kameda Medical Center between 1989 and 1995. RESULTS: Sixty-two of 71 patients were examined postoperatively for voice quality. Twenty patients (32%) had hoarseness develop caused by VCP, as confirmed by laryngoscopy. The left recurrent laryngeal nerve had been sacrificed in 1 patient during surgery, but it was preserved in the remaining 19 patients. Unilateral left VCP was noted in 19 patients, and bilateral VCP occurred in 1 patient. The incidence of VCP was higher in those patients who underwent surgery for type I aneurysms (9 of 14 patients, 64%). In 16 of the 19 patients (84%) who received follow-up for > 6 months, vocal cord movement did not return to normal. Surgery to improve voice quality, arytenoid adduction in five patients and intracordal injection in two patients, was performed with success. CONCLUSIONS: Our results indicate that surgery for TAA is associated with a relatively high incidence of VCP. VCP occurred despite preservation of the recurrent laryngeal nerve, and the paralysis did not show a spontaneous recovery even 6 months after surgery.

Adult↗