Toshiaki Ota

Pharmacologic intervention for ischemic brain edema after retrograde cerebral perfusion

Retrograde cerebral perfusion has recently been the focus of interest as a simple new technique of brain protection during aortic arch operations. We undertook the experimental protocol of 120 minutes of retrograde cerebral perfusion followed by antegrade reperfusion. Eighteen mongrel dogs were used. Retrograde cerebral perfusion was maintained at a flow rate of 150 to 250 ml/min to keep the perfusion pressure from 15 to 25 mm Hg. Animals were divided into three groups as follows: in group I, no treatment was received during and after retrograde cerebral perfusion; in group II, mannitol (2 gm/kg) was administered before cardiopulmonary bypass was restarted; and in group III, antivasospastic substance (1,2-bis nicotinamido]-propane) was continuously injected during and after retrograde cerebral perfusion (1 mg/kg per minute). Cerebral blood flow decreased during retrograde cerebral perfusion in all three groups. Cerebrovascular resistance showed marked increases 30 and 60 minutes after cardiopulmonary bypass was restarted in group I compared with the values in groups II and III (group I: 3.35 +/- 0.73 and 5.00 +/- 1.57 mm Hg/ml per 100 gm per minute; group II: 1.30 +/- 0.33 and 1.03 +/- 0.17 mm Hg/ml per 100 gm per minute; group III: 1.24 +/- 0.41 and 0.98 +/- 0.24 mm Hg/ml per 100 gm per minute). The oxygen extraction level was reduced by cooling, but it rose to a higher level as a result of significant desaturation of returned blood even in deep hypothermia during retrograde cerebral perfusion. Both cerebral metabolic rate of oxygen and cerebral metabolic rate of glucose remained at low levels during retrograde cerebral perfusion. Ratios of cerebral blood flow to cerebral metabolic rate of oxygen and cerebral blood flow to cerebral metabolic rate of glucose were markedly reduced during retrograde cerebral perfusion. Intracranial pressure showed significant increases 30 and 60 minutes after cardiopulmonary bypass was restarted in group I compared with values in group II or group III (group I: 22.7 +/- 2.8 and 20.6 +/- 5.1 mm Hg; group II: 6.3 +/- 1.8 and 5.3 +/- 1.3 mm Hg; group III: 4.2 +/- 1.7 and 7.7 +/- 2.8 mm Hg). Water content of the brain tissue in group I (77.54% +/- 0.29%) was significantly higher than that in group II (74.71% +/- 0.76%) or group III (74.14% +/- 0.48%). These data suggest that the supply of oxygen or glucose by retrograde cerebral perfusion is not enough to maintain sufficient cerebral metabolism, which may cause brain edema during antegrade reperfusion.(ABSTRACT TRUNCATED AT 400 WORDS)

Foot Venous Pressure Measurement in Patients with Varicose Veins

For the evaluation of the severity of varicose veins, foot venous pressure (FVP) measurements utilizing manual calf compression were applied to 52 limbs with varicose veins (group V) and 12 limbs of healthy volunteers (group C). Group V was divided into three groups: group V1 comprising 37 limbs without stasis syndrome, group V2 comprising 9 limbs with pigmentation, and group V3 comprising 6 limbs with preulcerative or ulcerative skin change. First, comparison of manual calf compression with the toe-stand test was performed, wherein a higher reproducibility was revealed for subjects undergoing manual calf compression. Also, a lower ambulatory venous pressure (AVP) and a higher percentage of FVP drop (%drop = [pressure at rest-AVP]/pressure at rest) was obtained with manual calf compression, confirming that this method apparently emptied the calf venous pool. Based on these findings, FVP at four seconds after compression (4SP) and its ratio of increase (4SR% = [4SP - AVP] / [pressure at rest - AVP]) were instituted by use of this method, in addition to AVP, % drop, and 50%/90% of calf-refilling times (RT50/RT90). When the values of the four groups were compared, differences were insignificant between groups C and V1, while significant differences were found between groups V2 (continued on next page) (Abstract continued) or V3 and groups C or V1 in all parameters examined. The number of abnormal limbs that had values beyond the ranges for group C increased from group V1 to group V3. Such abnormalities were best revealed by 4SR% and RT50. In the postoperative FVP measurements of 17 limbs, all parameters of all limbs were restored to the normal range, except for % drop of 4 limbs, and 4SR%, RT50, and RT90 of 1 limb. Based on these findings, all parameters examined in this study were considered to be sufficient for the evaluation of the severity of varicose veins. In particular, 4SR% and RT50, which reflect venous reflux in the early venous refilling phase, were the best diagnostic parameters. The usefulness of FVP measurement utilizing manual calf compression and the significance of the early phase of venous refilling in the varicose veins limbs were confirmed.

Acute Left Atrial Thrombus Causing Cardiogenic Shock Following Mitral Valve Replacement : Report of a Case

We report herein the rare case of a 53-year-old woman who developed cardiogenic shock due to an acute left atrial thrombus following replacement of the mitral valve. A definitive diagnosis was not able to be made using precordial echocardiography because of the broad, flat shape of the thrombus; however, transesophageal echocardiography imaged the thrombus in detail. The patient was initially stabilized by percutaneous cardiopulmonary support after which a thrombectomy was successfully performed.

A rare case of multiple atherosclerotic aneurysms involving the femoral artery

Atherosclerotic aneurysm of the deep femoral artery is a rare peripheral aneurysm that is likely to have associated aortoiliac aneurysms. The case of a patient who had five atherosclerotic aneurysms located in the abdominal aorta, bilateral common iliac arteries, and the left common femoral and deep femoral arteries is reported. He underwent a semi-emergency operation for the aneurysm of the deep femoral artery, followed by a two-stage operation for the aortoiliac aneurysms. The aneurysm of the deep femoral artery was repaired, and reconstruction of the distal deep femoral artery successfully performed with direct anastomosis to the superficial artery. In this report, the clinical presentation of multiple atherosclerotic aneurysms and the details of surgical reconstruction are described.

Retrograde Cerebral Perfusion for Aortic Arch Operation

Deep hypothermic retrograde cerebral perfusion (RCP) has recently been the focus of interest as a simple new technique of brain protection during the operation for thoracic aneurysms. During the period from January 1991 to July 1994, 21 consecutive patients underwent operations on the various portions of the thoracic aorta with the use of deep hypothermic RCP. There were 10 men and 11 women, ages ranging from twenty-eight to seventy-eight (mean 61.4) years old. There were 9 cases with true aortic aneurysm, and 12 with dissecting aneurysm. In 8 patients (38.1%) the procedures were done on an emergency basis for ruptured/impending ruptured aneurysms or acute dissecting aneurysms. Four patients died before the adequate assessment of their neurologic function. One patient had a cerebral infarction probably due to dissection of the left common carotid artery. The remaining 16 patients showed clear consciousness and had no serious neuro logic complications postoperatively. Total perfusion time averaged 297 ± 110 minutes (ranging from 162 to 548 minutes). Rectal temperatures were 20.1 ± 1.4°C (ranging from 18.0 to 22.5°C). RCP time averaged 51.3 ± 13.9 minutes (ranging from twenty-seven to eighty minutes). Blood gas analysis of the returned blood sampled from the left common carotid artery or the innominate artery and the ophthalmoscopic findings demonstrated the insufficiency of blood and oxygen supply to the brain during RCP. Therefore, RCP time should be shortened and pharmacologic cerebral protection is recommended to reduce neurologic complications during operations on the thoracic aorta using RCP.

Assessment of flow velocity in saphenous vein graft using the Doppler guidewire

The purpose of the study is to evaluate flow velocity characteristics in saphenous vein graft for coronary artery bypass grafting, especially in the graftnative vessel anastomotic site. The flow velocity was measured in 13 patients with saphenous vein graft (Group I) using a Doppler guidewire, and values were compared with those in patients who had severe (≧75%, Group II, n=31) or intermediate (<75%, Group III, n=27) coronary artery stenosis. In Group I, the flow velocity data were measured in the graft, in the anastomotic site, and in the native artery distal to the anastomosis, and in Groups II and III data were measured proximal to the stenosis, in the stenosis, and distal to the stenosis. In the saphenous vein graft, average peak velocity (APV) was significantly lower than that proximal to the stenosis. The APV increased significantly from the graft to the anastomotic site (13.3±7.2 → 36.2±15.8 cm/s,p<0.001). The APV in the anastomotic site was significantly lower than that in the stenotic site in Group II (Group II: 100.5±54.7 cm/s,p<0.001), but it was similar to that in Group III (Group III: 58.6±25.2 cm/s). The APV distal to the anastomosis in Group I was normal (22.4±8.0 cm/s), and it was significantly faster than the APV distal to the stenosis in Group II (Group II: 11.7±8.0 cm/s,p <0.001) or Group III (Group III: 15.9±8.2 cm/s,p< 0.05). In Group I, the diameter of saphenous vein graft was significantly larger than that of the native distal artery (4.23±0.85 vs 2.06±0.17 mm,p<0.001), and the Doppler-derived percent cross-sectional area stenosis at the anastomosis showed a significant correlation with the angiographically derived percent crosssectional area stenosis of the graft to the native distal artery (r=0.95,p<0.001). From these results it was thought that the increase of the APV from the graft to the anastomosis was due to caliber change from the graft to the native artery.

Mitral valve replacement after atrioventricular canal repair in adults: Report of three cases

Three cases of adults who required a mitral valve replacement (MVR) following repair of an atrioventricular (AV) canal are presented herein. In adult patients with an AV canal, the deformity of the mitral valve is sometimes too advanced for adequate repair, and therefore, residual mitral regurgitation frequently causes intractable cardiac failure despite appropriate medical management. Thus, for adults with an AV canal associated with severe valvular deformities, MVR should be considered from the initial operation to obtain a significantly better outcome.

Experimental Manufacture of a Catheter for the Measurement of Blood Flow Rate

The authors manufactured an experimental catheter to obtain blood flow rate, measuring not only the flow velocity but also the vessel diameter. This catheter consists of 3F Doppler and 7F external sheath catheters, and four thin wires 3 cm in length are attached to the catheters at both tips at a 90° pitch. After the insertion of the catheter into the vessel, vessel diameter is calculated from the maximal width of the wires, which are expanded to a spindle shape inside the vessel; the maximal width is corrected with calibration metal markers also attached at the proximal site of the external sheath catheter. The flow veloc ity of the blood is calculated with the FFT (Fast Fourier Transform) analyzer. In experimental circuits as well as in the canine aorta, wires were adequately expanded, and the catheter was placed at the center of the tube or the aorta. The blood flow rate, which was calculated as a product of flow velocity and vessel diameter, was well correlated to that from the electromagnetic flowmeter, not only in the experimental circuits, but also in the canine aorta.

Clinical Application of Angioscopy in the Field of Cardiovascular Surgery.

レーザー血管形成術あるいは冠血行再建術中に血管内視鏡による血管内病変の観察を行った.慢性下肢閉塞性動脈硬化症に対するレーザー血管形成術において血管内視鏡を施行した23例のうち19例(83%)で閉塞または狭窄病変の観察が可能であった.血管内病変の観察率は病変の部位により異なり,大腿動脈より末梢側では13例全例で観察が可能であったのに対して,腸骨動脈領域では10例中6例(60%)が観察可能であった.観察できなかった4例はいずれも血管の屈曲,蛇行が強い症例であり,病変部位を正面視することができなかった.一方,冠血行再建術中の血管内視鏡による観察を計7例で実施したが,いずれも良好な画像が安定して得られ,病変部,冠動脈吻合部および吻合部より末梢側の冠動脈内腔の状況が観察された.以上より血管内視鏡は今後心臓血管外科領域において必須の術中診断法となると考えられた.