Takeshi Miyairi

Open stent-grafting for aortic arch aneurysm is associated with increased risk of paraplegia

BACKGROUND Open surgery using the endovascular stent-graft is a novel technique that lessens the invasiveness of surgery for the aortic arch. However, the outcome of this procedure remains uncertain. METHODS Between November 1996 and July 2000, a total of 19 patients underwent open surgery using an endovascular stent-graft for thoracic aortic aneurysms. There were 15 men (78.9%) and 4 women (21.1%). Patient age ranged from 29 to 82 years (mean 69.3 years, median 74 years). Atherosclerotic thoracic aortic aneurysms were present in 17 patients (89.4%) and aortic dissection in 2 patients (10.5%). RESULTS Two patients (10.5%) died in the hospital and 4 patients (21.1%) presented with paraplegia postoperatively. Among the 4 patients with postoperative paraplegia, 1 case was complicated with intraoperative aortic dissection. The other 3 patients with paraplegia had spinal cord ischemic time of more than 60 minutes and intraoperative body weight gain of more than 4 kg. Of these 3 patients, hemodynamic instability after cardiopulmonary bypass was observed in 1 patient and cholesterin embolus in the anterior spinal artery was found at autopsy in another. On univariate analysis, age greater than 75 years was the only risk factor associated with paraplegia (p < 0.05). Autopsy findings for the 2 patients showed that the Adamkiewicz arteries were not blocked by the stent-graft in either patient. CONCLUSIONS Intraoperative aortic dissection, embolization of the intercostal arteries, long ischemic time of the spinal cord, and excessive weight gain during operation may have been associated with the high incidence of paraplegia after open surgery using the endovascular stent-graft.

Bridging annuloplasty for common atrioventricular valve regurgitation

Progressive common atrioventricular valve regurgitation is a serious condition in children with a univentricular heart. We developed a repair procedure that consists of using a Teflon tape bridge and total circular annuloplasty to divide the common atrioventricular valve into two atrioventricular valves. This procedure was performed in 2 infants, and the results were satisfactory. Details of the technique are described.

Rapid diagnosis and management of intraoperative myocardial infarction during valvular surgery: using intraoperative transesophageal echocardiography followed by emergency coronary artery bypass grafting without coronary angiography.

A 68‐year‐old man was admitted to undergo elective mitral valve surgery. Although the preoperative coronary angiography was normal, the patient suffered a myocardial infarction that resulted in untreatable collapsed hemodynamics. After inferring the responsible occluded coronary artery from the segmental wall motion abnormality detected in intraoperative transesophageal echocardiography, together with the anatomy found in preoperative coronary angiography, we performed an emergency coronary artery bypass graft surgery without a new angiography. This procedure resulted in survival of a potentially life‐threatening situation. In selected cases, this therapeutic strategy may lead to reduction of mortality as a result of the intraoperative myocardial infarction. (ECHOCARDIOGRAPHY, Volume 22, November 2005)

Ultrasonic evaluation of graft anastomoses during coronary artery bypass grafting without cardiopulmonary bypass

Performance of the graft-to-coronary anastomosis in coronary artery bypass grafting without cardiopulmonary bypass is more difficult than conventional coronary artery bypass grafting. We report a new method that uses high-frequency epicardial echocardiography to detect technical errors and inadequacies in graft anastomoses. This method improves the operative outcome and enables detection of septal perforator branches and deeply embedded coronary arteries during coronary artery bypass grafting without cardiopulmonary bypass.

Right heart mini-pump bypass for coronary artery bypass grafting: experimental study

BACKGROUND Visualization of the left circumflex arteries during off-pump coronary artery bypass grafting (CABG) causes hemodynamic disturbance. We investigated whether right heart mini-pump bypass (RHB), using a centrifugal pump, improved the safety of this procedure by studying the influences of different heart displacement positions, the Trendelenburg maneuver and RHB on hemodynamics. METHOD Hemodynamic parameters in eight mongrel dogs (15.5-20 kg) were continuously monitored at a fixed heart rate of 80 beats/min through a conventional median sternotomy. The posterior descending artery (PDA) and left circumflex artery (LCX) were exposed using an Octopus tissue stabilizer. After evaluating the influence of the Trendelenburg maneuver on hemodynamics, a heparin-coated centrifugal pump without an oxygenator was introduced and the impact of different pump flow volumes was investigated during RHB. RESULTS LCX exposure caused significant decreases in aortic flow (to 35. 1+/-12.8%) and arterial mean pressure (to 66.1+/-9.3%) compared with baseline (P<0.001). In contrast to PDA exposure, values remained significantly decreased during the Trendelenburg maneuver. On the contrary, RHB significantly improved the hemodynamic impairments caused by both heart displacement procedures, especially LCX exposure, although 100% pump flow significantly increased left atrial pressure to 131.3+/-19.5% (P<0.01). CONCLUSION Exposure of the LCX caused severe hemodynamic deterioration, which was not fully reversed by the Trendelenburg maneuver. In contrast, RHB significantly improved hemodynamics, and therefore this technique can be beneficial for CABG of LCX in the limited cases.

Intraoperative assessment of functioning mitral valve

A technique is presented that allows intraoperative assessment of mitral valve function with the heart filling and actively beating. This technique secures steady coronary perfusion and avoids possible air embolism of the coronary arteries. Repeated assessment and repair during reparative mitral operations are greatly facilitated when this technique is accompanied by warm blood cardioplegia.

Conventional repair and operative stent-grafting for acute and chronic aortic dissection

Conventional graft replacement of the ascending aorta and surgically endovascular stent-grafting of the proximal descending aorta were performed concomitantly in a 82-year-old woman with an acute DeBakey type II aortic dissection and a chronic DeBakey type IIIb aortic dissection. Postoperative computed tomography and angiography showed the adequately replaced ascending-aortic prosthesis, the well-expanded stent-graft, and the thrombosed false lumen in the descending aorta.

Arterial blood gas management in retrograde cerebral perfusion: the importance of carbon dioxide

OBJECTIVES Many interventional physiological assessments for retrograde cerebral perfusion (RCP) have been explored. However, the appropriate arterial gas management of carbon dioxide (CO2) remains controversial. The aim of this study is to determine whether alpha-stat or pH-stat could be used for effective brain protection under RCP in terms of cortical cerebral blood flow (CBF), cerebral metabolic rate for oxygen (CMRO2), and distribution of regional cerebral blood flow. METHODS Fifteen anesthetized dogs (25.1+/-1.1 kg) on cardiopulmonary bypass (CPB) were cooled to 18 degrees C under alpha-stat management and had RCP for 90 min under: (1), alpha-stat; (2), pH-stat; or (3), deep hypothermic (18 degrees C) antegrade CPB (antegrade). RCP flow was regulated for a sagittal sinus pressure of around 25 mmHg. CBF was monitored by a laser tissue flowmeter. Serial analyses of blood gas were made. The regional cerebral blood flow was measured with colored microspheres before discontinuation of RCP. CBF and CMRO2 were evaluated as the percentage of the baseline level (%CBF, %CMRO2). RESULTS The oxygen content of arterial inflow and oxygen extraction was not significantly different between the RCP groups. The %CBF and %CMRO2 were significantly higher for pH-stat RCP than for alpha-stat RCP. The regional cerebral blood flow, measured with colored microspheres, tended to be higher for pH-stat RCP than for alpha-stat RCP, at every site in the brain. Irrespective of CO2 management, regional differences were not significant among any site in the brain. CONCLUSIONS CO2 management is crucial for brain protection under deep hypothermic RCP. This study revealed that pH-stat was considered to be better than alpha-stat in terms of CBF and oxygen metabolism in the brain. The regional blood flow distribution was considered to be unchanged irrespective of CO2 management.

Minimally invasive limited pericardiectomy: the hybrid approach

This communication describes our clinical experience with the hybrid method, a video-assisted anterior minithoracotomy approach developed for minimally invasive limited pericardiectomy to treat 8 patients with massive pericardial effusion. The average operating time was 37.2 minutes, and there was no procedure-related morbidity or mortality. The mean follow-up period was 5.6 months, and there have been no recurrences. The hybrid approach can be accomplished irrespective of pleural adhesions. It eliminates the need for hemipulmonary collapse, making it more advantageous than the totally port-access thoracoscopic approach.

Midterm results after aortic valve-sparing operation

OBJECTIVES We have conducted aortic valve-sparing operation for patients having aortic root dilatation and almost normal aortic valve leaflets since August 1998, and here report midterm results. METHODS Patients with dilated aortic annulus or Marfans syndrome were treated with reimplantation, and the remaining patients with remodeling. Either 24 or 26 mm graft was selected based on aortic annular diameter and leaflet size. Aortic valve competence was assessed regularly with echocardiography. RESULTS Five patients (age: 29 +/- 13 yr), including 4 with Marfans syndrome, had undergone reimplantation, and 3 (age: 46 +/- 18 yr) remodeling by December 2000. Mean follow-up was 18 (range: 10-32) months, and no postoperative death has occurred and no reintervention has been required thus far. All the patients in the remodeling group showed only a small pressure gradient through the aortic valve and decreased left ventricular diameter. Two in the reimplantation group showed a pressure gradient exceeding 20 mmHg. Two Marfans syndrome patients in the reimplantation group showed slightly increased diastolic left ventricular diameter and 3 slightly increased systolic left ventricular diameter. Although aortic regurgitation had diminished in all patients by discharge, moderate aortic regurgitation recurred in 1 non-Marfans syndrome patient in the reimplantation group because of degenerated aortic valve. CONCLUSION Although postoperative aortic valve function was not perfect in all patients undergoing reimplantation, midterm results after aortic valve-sparing operation were generally satisfactory. Proper selection of patients, procedures, and graft size was thought to be important to ensure a favorable surgical outcome.