Chronic instrumentation and its lack of effect on the hemodynamics and regional myocardial blood flow of conscious dogs

The effects of chronic instrumentation on regional myocardial performance and regional myocardial blood flow were studied in 8 mongrel dogs. Regional segment lengths were measured by an ultrasonic dimension gauge technique at two areas of the left anterior descending coronary artery (LAD) and left circumflex coronary artery (LCX). Regional myocardial blood flow was measured by a tracer microsphere technique. These measurements were repeated while the animals were conscious on the 4th, 11th, 21st and 28th days after instrumentation. On the 4th day, the heart rate was rather high and regional shortening at both the LAD and LCX areas remained suppressed. After the 11th day, hemodynamic variables such as heart rate, left ventricular pressure and regional wall motion were fairly constant. Regional myocardial blood flow and its distribution were also constant throughout the experimental period. Fibrosis of the epicardium invariably induced by surgical procedures did not affect the distribution of regional blood flow as compared with that of the interventricular septum. Thus, a stable hemodynamic state was recorded after the 11th day following surgical manipulation and the implantation of sensors and catheters did not affect the level of regional myocardial blood flow or its distribution at rest. Such long term reproducible measurements of regional wall motion and regional myocardial blood flow may facilitate chronic studies of cardiovascular physiology.

Importance of Fe2+-ADP and the relative unimportance of OH in the mechanism of mitomycin C-induced lipid peroxidation

The mechanism of mitomycin C-induced lipid peroxidation has been studied at pH 7.5, using systems containing phospholipid membranes (liposomes) and an Fe3+-ADP complex with purified NADPH-cytochrome P-450 reductase. Both O2- and H2O2 are generated during the aerobic enzyme-catalyzed reaction in the presence of mitomycin C. Hydroxyl radical is formed in the reaction by the reduction of H2O2. This is catalyzed by the Fe2+-ADP complex in a phosphate buffer or to a lesser extent when in a Tris-HCl buffer. The reduction of Fe3+-ADP to Fe2+-ADP is mainly achieved by O2-. The resulting Fe2+-ADP in the presence of O2 forms a perferryl ion complex which is a powerful stimulator of lipid peroxidation. However, the formation of such an iron-oxygen complex is strongly inhibited by phosphate ions, which do not interfere with the generation of OH radicals. These findings suggest that, since lipid peroxidation occurs in a Tris-HCl buffer (but not in a phosphate buffer), the OH radical is unlikely to be involved in the observed lipid peroxidation process.

Topographic electroencephalographic study of transient ischemic attacks

Twenty-five patients with TIAs in the carotid artery distribution were studied by means of computed mapping of EEG (CME) and conventional EEG. In addition, CT scan and cerebral angiography, and in 10 patients rCBF measurements were performed. The CME provided topographic maps of the average power spectra for each of 6 frequency bands from 2.0 to 29.5 Hz which were displayed two-dimensionally in a color-coded isopower format. EEG abnormalities were analyzed and the results of the two different methods of EEG interpretation were compared. Sixty-eight percent of the patients showed unilateral abnormalities on CME appropriately lateralized to the clinical symptoms even after these symptoms had cleared completely. Furthermore, 88% of those who were examined within 2 weeks of last TIA showed corresponding CME abnormalities. Only 3 out of 10 TIA patients who had rCBF studies showed reduction of blood flow on the appropriate hemisphere, whereas 7 of the 10 patients had corresponding CME abnormalities. Comparing the results of the CME and of conventional EEG reading revealed the CME to be slightly more sensitive in detecting asymmetrical voltage depression of background activity than the conventional reading of the EEG, while the latter detected low amplitude sporadic activities which were missed by CME. Both methods were equally sensitive in detecting slow wave foci and non-transient symmetrical changes. The two most significant points of this report are the following: first, 68% of the TIA patients studied had residual unilateral abnormalities in CME in their symptom-free period. In the subset of patients subjected to rCBF studies only 30% showed residual flow aberrations, whereas 70% of the same subset demonstrated unilateral abnormalities in CME. Second, though conventional EEG reading by an experienced electroencephalographer can nearly match the performance of CME the CME format makes subtle but useful EEG findings readily available to the uninitiated. The CME also quantifies the data making objective comparisons more amenable to software manipulations for further studies.

Postoperative evaluation of extracranial-intracranial arterial bypass by means of ultrasonic quantitative flow measurement and computed mapping of the electroencephalogram

As an objective evaluation of extracranial-intracranial (EC/IC) bypass operation, we studied 10 patients with occlusive cerebrovascular disease after EC/IC bypass operation using ultrasonic quantitative flow measurement (UQFM) and the computed mapping of the electroencephalogram (CME). After the operation, to evaluate the efficacy of the bypass operation, we studied all patients by UQFM and CME before and during compression of the superficial temporal artery (STA). In a control series of cases, the change in common carotid blood flow during STA compression was not statistically significant, and the findings of CME were unchanged during STA compression. In the cases with bypass surgery, reduction of the common carotid blood flow during STA compression was obvious and statistically significant (P less than 0.001). Additionally, in 5 of the 10 cases, the CME findings were aggravated during STA compression. Therefore, in these 5 cases the brain with bypass seems functionally dependent upon the bypass flow. It is suggested that the EC/IC bypass is effective at least in these 5 cases. The UQFM and the CME, which are noninvasive and simple, are very useful for postoperative evaluation of EC/IC bypass grafts from a hemodynamic and functional point of view.

[Some considerations on surgical approaches to the anterior communicating artery aneurysms--radiological study of 122 cases]

We studied the operative approaches to anterior communicating artery aneurysms by means of reviewing preoperative angiogram and operation records. During the past 5 years, 117 patients with anterior communicating artery aneurysms were operated on in our hospital. Among these, we examined 112 cases of which preoperative angiogram and operation records were satisfactory for this study. We checked the next points on the preoperative angiograms. Neck of aneurysm-planum sphenoidal distance. Direction of the anterior communicating artery. It means which A2 is anterior to the other A2 in the lateral view of angiogram. Size of aneurysm. We checked the next points on the operation records. Operative approach and the side of craniotomy. When the pterional approach was taken, the rectal gyrus was aspirated or not. This analysis derived these two conclusions as below. 1. In the literature, as the operative approach to anterior communicating artery aneurysm, the pterional approach has a lot of advantages. For example, the pterional approach was accomplished without extensive frontal lobe retraction, without mobilization of the temporal lobe, without sacrificing the olfactory tract, and so on. Moreover, in early stage after onset of SAH, it is possible to remove the subarachnoid blood extensively without obvious brain damage by the pterional approach. In this study, we paid attention to the correlation between the neck-planum sphenoidal distance and the fact of aspiration of the rectal gyrus in the pterional approach. The result is that the higher aneurysmal neck was, the more frequently the rectal gyrus was aspirated. So, if the neck-planum sphenoidal distance is under 12 mm, which includes the majority of the cases (94% of cases), we think the pterional approach is the best approach for anterior communicating artery aneurysm.(ABSTRACT TRUNCATED AT 250 WORDS)

[Use of real-time ultrasonography in neurosurgical operations]

The authors' experience with the application of real-time ultrasonography during 29 and after 3 neurosurgical operations is reported. Intraoperative sonography was performed in 29 cases. The neurosurgical operations include aneurysm surgery in 13 cases, removal of intracerebral hematoma in 11 cases, neoplasm surgery in 2 cases, and so on. Moreover, sonographic examination through bone defect was performed in 3 cases after decompression craniectomy. The instrument used was an ATL (Advanced Technology Laboratories, Bellevue, WA, USA) mechanical sector scanner of which scanhead contained transducers of three frequencies: 3, 5 and 7.5 MHz. The scanhead was wrapped with a sterile rubber bag after acoustic coupling gel had been applied to the head's tip. Then the scanhead was placed on the dura and ultrasonic examination was performed. The result was that the lesion was clearly identified and localized in all cases except for three cases of mild subarachnoid hemorrhage. In addition, in the two cases of needle aspiration of cyst or hematoma, the needle was easily identified and needle aspiration was performed safely and accurately. Moreover, during aneurysm surgery, aneurysm itself was detected in two cases by the real-time ultrasonic imaging. Especially, in the case with large aneurysm of the left middle cerebral artery, the findings about the aneurysmal wall, that is to say, which part is thick and which part is thin, could be obtained. Prior to the operation of aneurysm, cerebral angiogram and computerized tomographic scan are always examined thoroughly, but information about aneurysmal wall can be rarely obtained by them.(ABSTRACT TRUNCATED AT 250 WORDS)

Experimental myocardial infarction: effects of a lipid peroxide, 13-hydroperoxy linoleic acid on coronary circulation in rats

Effects of 13-hydroperoxy linoleic acid on coronary circulation and vasculature were investigated using an electrocardiographic (ECG) and scanning electron microscopic (SEM) techniques. After the intra left ventricular injection of 13-hydroperoxy linoleic acid to rats the ischemic ECG changes, i.e., elevations of the ST segment and T wave, were observed with the reduction of systemic blood pressure and heart rate. By the SEM examination, the endothelial injuries were found with the platelet aggregation in the blood flow and the adherence of leukocytes. Thus it was clearly found that 13-hydroperoxy linoleic acid caused the various endothelial injuries and thrombus formation leading to coronary arterial occlusion. These results suggest that lipid peroxide may play an important role in the pathogenesis of vascular diseases especially in coronary vascular bed and take part in the generation of the severe myocardial ischemia.

Intraoperative use of real time ultrasonography applied to aneurysm surgery

The intraoperative application of real time ultrasonography during 13 neurosurgical operations for intracranial aneurysms is reported. In 2 cases, the aneurysms themselves could be detected clearly by real time ultrasonic imaging. In the case of a large aneurysm, information about the nature of the aneurysmal wall was obtained. Other lesions coexisting with the aneurysm (namely, intracerebral hematoma, massive subarachnoid hemorrhage, and hydrocephalus) could be recognized clearly. Real time intraoperative ultrasonography is considered to be useful in aneurysm surgery.

Relationship between contrast enhancement on computed tomography and cerebral vasospasm in patients with subarachnoid hemorrhage

To elucidate the relationship between abnormal enhancement of the cisterns on computed tomography and cerebral vasospasm, we performed a systematic and prospective study in 60 patients with ruptured cerebral aneurysms. There is a significant relationship between the findings of contrast-enhanced computed tomography (CECT) within Day 3 of rupture and cerebral vasospasm. Among 37 patients undergoing CECT between Day 0 and Day 3, 17 (46%) showed prominent increases in density in the region around the circle of Willis and its branches. In 13 of 17 cases (76%), severe vasospasm with motor paralysis occurred. In the remaining 4 cases (24%) with only slight or no cerebral vasospasm, the hematoma in the subarachnoid space was removed surgically by Day 3. In 19 of 20 cases without remarkable CECT, no severe cerebral vasospasm with motor paralysis occurred. There is no significant relationship between the CECT findings after Day 3 and cerebral vasospasm. The results indicate that the prominent increase in density in the region of the circle of Willis and its branches often observed on CECT within Day 3 of subarachnoid hemorrhage is useful for prediction of the occurrence of cerebral vasospasm and also provide information on the pathogenesis of cerebral vasospasm.

Functional significance of collaterals during ameroid-induced coronary stenosis in conscious dogs. Interrelationships among regional shortening, regional flow and grade of coronary stenosis

We studied the relationships among collateral flow, regional myocardial shortening and the grade of coronary stenosis during ameroid-induced chronic coronary constriction in 22 conscious dogs. A radiolucent ameroid, a Doppler flow probe and a cuff occluder were placed on the left circumflex coronary artery (LCx). Regional myocardial shortening and regional myocardial blood flow were assessed simultaneously using ultrasonic dimension gauges and the tracer microsphere technique, respectively, during temporary occlusion of the LCx. Regional hypokinesia and ischemia were attenuated as a function of time during progressive coronary stenosis. Fifty percent recovery and full recovery of regional shortening during occlusion were observed 19 +/- 3 and 25 +/- 4 days after instrumentation, respectively, when the endocardial blood flow recovered from 0.42 +/- 0.07 ml/min/g at 7 days to 0.56 +/- 0.07 and 0.80 +/- 0.05 ml/min/g, respectively. Greater than 75% coronary stenosis coincided with collateral development, as estimated from regional shortening rate and the appearance of angiographically opacified collaterals. Our study confirms that the development of collateral vessels reduces regional ischemia and hypokinesia induced during abrupt coronary occlusion in a canine model.

CT and arteriographic comparison of patients with transient ischemic attacks--correlation with small infarction of basal ganglia

Fifty patients presenting clinically with TIAs were examined angiographically. Twenty one patients (42%) had no abnormality. Twenty patients (40%) had stenosis or occlusion in the MCA, ACA or intracranial carotid, whereas 11 (22%) had involvement of their extracranial internal carotid artery. Seven of the 28 CTs performed showed basal ganglia infarcts. This suggests that the cause for the TIA was an infarct in the vascular territory of a lenticulostriate artery.

[Dynamic pathophysiology of cerebral infarction and revascularization. III. Changes of regional cerebral blood flow]

Thirty-eight patients with occlusive cerebrovascular disease were followed with regional cerebral blood flow (rCBF) measurement, angiography and computerized tomography (CT) to know the time course of rCBF in cerebral infarction. The rCBF study was carried out by the 133Xe intracarotid injection method with 16 scintillation detectors. They were allocated to two groups according to the findings on angiograms; 15 patients having any change of occlusive lesion (the group of no-recanalization ) and 23 patients showing reopening of occluded vessels (the group of recanalization). A mass sign and an extent of cerebral infarction were observed on CT. In the group of no-recanalization, a mean value of rCBF (mean rCBF) in acute stage was well correlated to the severity of ischemic stroke. In minor completed strokes the average mean rCBF was 35.8 +/- 3.7 ml/100g/min, which is significantly higher than that in major strokes and progressing strokes of 24.8 +/- 3.9 ml/100 g/min (p less than 0.001). Sequential change of mean rCBF was not prominent in the group of no-recanalization. However, rCBF change was conspicuous in the group of recanalization. In acute stage of recanalization, rCBF were markedly affected by the presence of mass sign (cerebral edema) on CT. When CT showed midline shift of structure, mean rCBF was markedly reduced, and when without midline shift, focal hyperemic areas were sometimes observed in the revascularized area. Thus, the inhomogeneity of rCBF was characteristic in cases with recanalization. The focal hyperemia usually disappeared within one week in cases of minor stroke and lasted until 2 or 3 weeks in cases of major stroke. In chronic stage, mean rCBF decreased, and there was no significant difference of averaged rCBF between two groups. Those findings suggests that the main factor influenced on the sequential change of rCBF is reopening of occluded vessels. Regional CBF may depends both on the degree of cerebral edema and the extent of vasoparesis after revascularization. In chronic stage CBF value is not always dependent to the presence of occlusive lesion but might be reflected in the total brain function.

[Dynamic pathophysiology of cerebral infarction and revascularization. I. Ischemic cerebral edema]

A natural history of ischemic cerebral edema was analyzed in 100 patients with occlusive cerebrovascular diseases admitted within one week of onset, with serial computed tomography (CT) and angiograms. Cerebral edema was defined as a low-density area with mass sign on CT. A total of 446 studies of CT were performed. In 40 patients with major completed stroke admitted 24 hours of onset, a total of 73 studies of CT were taken within 48 hours of onset, and a timing of appearance of cerebral edema was analyzed. Patients were allocated to two groups according to the findings on angiograms; 68 patients who showed occlusive lesions on sequential angiograms (the group of no-recanalization), and 32 patients who showed reopening of occluded vessels on the first or sequential angiograms (the group of no-recanalization). In the group of no-recanalization a low-density area gradually appeared between 6 and 24 hours of onset A. mass sign reached its peak on the 3rd day with a peak incidence of 56%, and midline shift was present in 30% of the cases. It was resolved within 2 weeks in most cases. In the group of recanalization, a low density area appeared after 4 hours and rapidly increase after 6 hours. All patients had a low-density area at 12 hours of onset. A mass sign progressed until the 6th day with a peak incidence of 82%, and midline shift was present in 50% of the cases. The duration of mass sign was longer than that in the group of no-recanalization. These results suggest that the permissible duration of ischemia is considered to be within 6 hours of onset in profound ischemia. After 6 hours, ischemic tissue damage may not be reversible by the revascularization, even if CT shows no change during ischemia. An abrupt revascularization may not contribute to the recovery of brain damage, but accelerate the ischemic cerebral edema.

Prevention of vasospasm by early operation with removal of subarachnoid blood

Sixty-four patients who were operated on within 4 days after acute subarachnoid hemorrhage are included in this study. All patients underwent preoperative computed tomographic (CT) scanning, and the amount and distribution of subarachnoid blood clot were noted. Operation was carried out by the frontobasal lateral approach, and the subarachnoid clot was removed by microsurgical suction-irrigation after clipping of the aneurysm. Immediate postoperative CT scanning was performed to evaluate the completeness of the subarachnoid blood clot removal. The presence or absence of postoperative vasospasm was determined with angiography performed between the 7th and 10th postoperative days. All patients were, of course, also evaluated for evidence of neurological deterioration. Approximately two-thirds of the patients in this series showed high density subarachnoid blood clot on the preoperative CT scan. The postoperative CT scans showed that it was possible to remove the majority of the blood clot except that located in the frontal interhemispheric fissure, the posterior part of the insular cistern on the approached side, and all of the insular cistern on the contralateral side. There was no spasm or only mild spasm in any site where the blood clot had been successfully removed. Delayed neurological deficits occurred only in those cases in which subarachnoid blood clot remained in the cisterns. These results suggest that it is possible to prevent intracranial arterial spasm and associated neurological deterioration by early operation and removal of clotted blood from the subarachnoid space.

Topographic electroencephalographic study of cerebral infarction using computed mapping of the EEG

Computed mapping of the electroencephalogram (CME) is a newly developed method using a microcomputer system that displays the scalp topograph as the square roots of the average power spectra over each EEG frequency band on a color television screen. This new device has been employed in an examination of functional lesions in 20 patients with aphasia due to cerebral infarction. The results were compared with those of computer tomography (CT) and regional cerebral blood flow (rCBF) studies using intracarotid 133Xe. A high-voltage focus of slow components and an asymmetrical distribution of alpha activity were regarded as signs of functional lesions on CME. Twelve patients showed high-voltage foci and six showed asymmetrical alpha activity on CME, which correlated well with the lesions on CT and/or rCBF studies. Especially in patients with motor aphasia, CME demonstrated the abnormality in advance of the appearance of a low-density area on CT. Compared with conventional EEG interpretation, CME is very useful in topographic and objective diagnosis of functional lesions, although the source of the data is the same as for the conventional EEG.