Whisnant, Jack P.

Ligation of various combinations of arteries in the neck in 21 dogs demonstrated that there is little clinical effect following ligation of three or less of the major arteries to the brain and that most dogs survive after all the major arteries to the brain are ligated in the neck. A procedure is described in which the collateral circulation is determined by injection of liquid vinyl acetate into the arterial tree in dogs immediately after death subsequent to one-stage ligation of all the major arteries to the brain. The main anastomotic channels are branches of the costocervical and omocervical arteries that join muscular branches of the vertebral arteries beyond the ligated points. No anastomotic channels were detected in the carotid systems.

Abstract —At the community level, the effect of national programs in increasing hypertension awareness, prevention, treatment, and control is unclear. This study evaluated the degree of detection and control of high blood pressure in a random population-based sample of Olmsted County, Minnesota, residents ≥45 years old, of whom 636 subjects among 1245 eligible residents agreed to participate. Home interview and home and office measurements of blood pressure were used to estimate awareness, treatment, and control rates for hypertension in the community. Mean blood pressures (±SD) were 138/80±20/12 mm Hg for men and 137/76±23/11 mm Hg for women. The overall prevalence of hypertension was 53%. The percentage of subjects with treated and controlled hypertension was 16.6%. Thirty-nine percent of subjects were unaware of their hypertension. Despite clinical trial evidence of reduced morbidity and mortality with antihypertensive therapy, recently reported national data suggest a leveling-off trend for treatment and control of hypertension. This population-based study supports these observations and suggests that at a community level, hypertension awareness and blood pressure control rates are suboptimal, presumably because of decreased attention to the detection and control of hypertension.

Background —Atrial septal aneurysm (ASA) is a putative risk factor for cardioembolism. However, the frequency of ASA in the general population has not been adequately determined. Therefore, the frequency in patients with cerebral ischemic events, compared with the frequency in the general population, is poorly defined. We sought to determine the frequency of ASA in the general population and to compare the frequency of ASA in patients with cerebral ischemic events with the frequency in the general population. Methods and Results —The frequency of ASA in the population was determined in 363 subjects, a sample of the participants in the Stroke Prevention: Assessment of Risk in a Community study (control subjects), and was compared with the frequency in 355 age- and sex-matched patients undergoing transesophageal echocardiography in search of a cardiac source of embolism after a focal cerebral ischemic event. The proportion with ASA was 7.9% in patients versus 2.2% in control subjects ( P =0.002; odds ratio of ASA, 3.65; 95% CI, 1.64 to 8.13, in patients versus control subjects). Patent foramen ovale (PFO) was detected with contrast injections in 56% of subjects with ASA. The presence of ASA predicted the presence of PFO (odds ratio of PFO, 4.57; 95% CI, 2.18 to 9.57, in subjects with versus those without ASA). In 86% of subjects with ASA and cerebral ischemia, transesophageal echocardiography did not detect an alternative source of cardioembolism other than an associated PFO. Conclusions —The prevalence of ASA based on this population-based study is 2.2%. The frequency of ASA is relatively higher in patients evaluated with transesophageal echocardiography after a cerebral ischemic event. ASA is frequently associated with PFO, suggesting paradoxical embolism as a mechanism of cardioembolism. In patients with cerebral ischemia and ASA, ASA (with or without PFO) commonly is the only potential cardioembolic source detected with transesophageal echocardiography.

Background —Atherosclerosis of the thoracic aorta is associated with stroke. The association between hypertension, a major risk factor for stroke, and aortic atherosclerosis has not been determined in the general population. Methods and Results —Transesophageal echocardiography was performed in 581 subjects, a random sample of the Olmsted County (Minnesota) population aged ≥45 years participating in the Stroke Prevention: Assessment of Risk in a Community (SPARC) study. Blood pressure was assessed by multiple office measurements and 24-hour ambulatory blood pressure monitoring. The association between blood pressure variables and aortic atherosclerosis was evaluated by multiple logistic regression, adjusting for other associated variables. Among subjects with atherosclerosis, blood pressure variables associated with complex aortic atherosclerosis (protruding plaques ≥4 mm thick, mobile debris, or ulceration) were determined. Age and smoking history were independently associated with aortic atherosclerosis of any degree ( P ≤0.001) and with complex atherosclerosis ( P =0.002), whereas sex, diabetes mellitus, and body mass index were not. Multiple systolic and pulse pressure variables (office and ambulatory), but none of the diastolic blood pressure variables, were associated with atherosclerosis and complex atherosclerosis, adjusting for age and smoking. Among subjects with atherosclerosis, the odds of complex atherosclerosis increased as ambulatory out-of-bed systolic blood pressure increased (odds ratio 1.43 per 10 mm Hg increase, 95% CI 1.10 to 1.87) and with hypertension treatment, adjusting for age and smoking history. Conclusions —High blood pressure is independently associated with aortic atherosclerosis. Among subjects with atherosclerosis, high blood pressure is associated with complex atherosclerosis.

Recently we have studied the role of surgical treatment of patients having occlusive cerebrovascular disease, particularly incipient stroke (or focal intermittent cerebrovascular insufficiency). This report concerns 35 pa-patients with incipient stroke in whom circulation was restored to normal by operation on an artery in an attempt to prevent transient ischemic episodes and cerebral infarction. Since all of the patients were neurologically normal at the time of the surgical procedure, we were concerned primarily with the risk of [see tablein the PDF file] the procedure, particularly in terms of cerebral infarction. The operative mortality rate was 8.5 per cent (three patients). Six patients (17 per cent) sustained cerebral infarcts. Four of these had mild neurologic deficits, usually consisting of clumsiness and mildly reduced discriminatory sensation in one hand; one had a severe neurologic deficit, and one died. Evidence shows that at least some of these infarcts resulted from emboli arising from the operative site at the time of or shortly after the operation. The results of long-term follow-up revealed that 66 per cent of the surgically treated patients were normal compared to 25 per cent of a contrast group; and 17 per cent of the treated patients had suffered cerebral infarcts compared to 40 per cent of the contrast group. The long-term results are thus similar to the immediate postoperative results. These findings simply indicate that an operated patient's prognosis was good over the long term if the cerebral ischemic episodes were relieved and if he sustained no complications from the surgical procedure.

This has been a summary of the clinical patterns in certain types of cerebrovascular disease with emphasis on occlusive disease. Knowledge concerning these categories is important in studying the results of various therapeutic technics and in selecting the correct treatment for some subdivisions where effective therapy exists.

Cerebral infarction is attended by extravasation of blood in varying degrees. The present study was undertaken to learn whether anticoagulant therapy increases the extravasation and thereby diminishes or negates possibly favorable therapeutic effects. A series of experiments on dogs is described and the clinical implications are discussed.