bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of adenosine on human coronary arterial circulation.
Authors: Wilson R F , Wyche K , Christensen B V , Zimmer S , Laxson D D
Published: June 2011

Adenosine is a potent vasodilator used extensively to study the coronary circulation of animals. Its use in humans, however, has been hampered by lack of knowledge about its effects on the human coronary circulation and by concern about its safety. We investigated in humans the effects of adenosine, administered by intracoronary bolus (2-16 micrograms), intracoronary infusion (10-240 micrograms/min), or intravenous infusion (35-140 micrograms/kg/min) on coronary and systemic hemodynamics and the electrocardiogram. Coronary blood flow velocity (CBFV) was measured with a 3F coronary Doppler catheter. The maximal CBFV was determined with intracoronary papaverine (4.5 +/- 0.2.resting CBFV). In normal left coronary arteries (n = 20), 16-micrograms boluses of adenosine caused coronary hyperemia similar to that caused by papaverine (4.6 +/- 0.7.resting CBFV). In the right coronary artery (n = 5), 12-micrograms boluses caused maximal hyperemia (4.4 +/- 1.0.resting CBFV). Intracoronary boluses caused a small, brief decrease in arterial pressure (similar to that caused by papaverine) and no changes in heart rate or in the electrocardiogram. The duration of hyperemia was much shorter after adenosine than after papaverine administration. Intracoronary infusions of 80 micrograms/min or more into the left coronary artery (n = 6) also caused maximal hyperemia (4.4 +/- 0.1.resting CBFV), and doses up to 240 micrograms/min caused a minimal decrease in arterial pressure (-6 +/- 2 mm Hg) and no significant change in heart rate or in electrocardiographic variables. Intravenous infusions in normal patients (n = 25) at 140 micrograms/kg/min caused coronary vasodilation similar to that caused by papaverine in 84% of patients (4.4 +/- 0.9.resting CBFV). At submaximal infusion rates, however, CBFV often fluctuated widely. During the 140-micrograms/kg/min infusion, arterial pressure decreased 6 +/- 7 mm Hg, and heart rate increased 24 +/- 14 beats/min. One patient developed 1 cycle of 2:1 atrioventricular block, but otherwise, the electrocardiogram did not change. In eight patients with microvascular vasodilator dysfunction (delta CBFV, less than 3.5 peak/resting velocity after a maximally vasodilating dose of intracoronary papaverine), the dose-response characteristics to intracoronary boluses and intravenous infusions of adenosine were similar to those found in normal patients.(ABSTRACT TRUNCATED AT 400 WORDS)
Sex differences in control of cutaneous blood flow.
Authors: Cooke J P , Creager M A , Osmundson P J , Shepherd J T
Published: June 2011

Women are far more likely than men to suffer from Raynaud's disease. The purpose of this study was to determine whether there are gender differences in local or central control of cutaneous blood flow that could account for the increased incidence of Raynaud's disease in women. To assess cutaneous blood flow, hand blood flow (HBF), finger blood flow (FBF), or skin perfusion (SP) was measured by fluid plethysmography, mercury strain-gauge plethysmography, or laser Doppler spectroscopy, respectively, in 47 volunteers. Basal HBF in men exceeded that of women (12.1 +/- 2.0 versus 6.2 +/- 1.5 ml/100 ml/min). Likewise, FBF in men surpassed that of women (19.5 +/- 4.1 versus 7.7 +/- 1.8 ml/100 ml/min). Similarly, SP in men was greater than that of women (270 +/- 42 versus 81 +/- 16 perfusion units). However, after total body warming (to induce a thermal sympatholysis), HBF in women exceeded that of men, suggesting that the lower basal HBF in women was due to increased sympathetic outflow to the extremities. Mental stress and deep inspiration reduced HBF and SP in men. Paradoxically, both of these maneuvers increased HBF and SP in women. To determine whether these paradoxical responses in women were due to the women's elevated basal sympathetic tone, these experiments were repeated after total body cooling in men to increase sympathetic tone and after total body warming in women to reduce sympathetic tone. Total body cooling reduced HBF and SP in men. Under these conditions, mental stress and deep inspiration induced vasodilation. In women, total body warming for 10 minutes increased HBF.(ABSTRACT TRUNCATED AT 250 WORDS)
Ten-year follow-up of survival and myocardial infarction in the randomized Coronary Artery Surgery Study.
Authors: Alderman E L , Bourassa M G , Cohen L S , Davis K B , Kaiser G G , Killip T , Mock M B , Pettinger M , Robertson T L
Published: June 2011

The Coronary Artery Surgery Study (CASS) randomized 780 patients to an initial strategy of coronary surgery or medical therapy. Of medically randomized patients, 6% had surgery within 6 months and a total of 40% had surgery by 10 years. At 10 years, there was no difference in cumulative survival (medical, 79% vs. surgical, 82%; NS) and no difference in percentage free of death and nonfatal myocardial infarction (medical, 69% vs. surgical, 66%; NS). Patients with an ejection fraction of less than 0.50 exhibited a better survival with initial surgery treatment (medical, 61% vs. surgical, 79%; p = 0.01). Conversely, patients with an ejection fraction greater than or equal to 0.50 exhibited a higher proportion free of death and myocardial infarction with initial medical therapy (medical, 75% vs. surgical, 68%; p = 0.04) although long-term survival remained unaffected (medical, 84% vs. surgical, 83%; p = 0.75). There were no significant differences either in survival and freedom from nonfatal myocardial infarction, whether stratified on presence of heart failure, age, hypertension, or number of vessels diseased. Thus, 10-year follow-up results confirm earlier reports from CASS that patients with left ventricular dysfunction exhibit long-term benefit from an initial strategy of surgical treatment. Patients with mild stable angina and normal left ventricular function randomized to initial medical treatment (with an option for later surgery if symptoms progress) have survival equivalent to those patients randomized to initial surgery.
Change of left atrial systolic pressure waveform in relation to left ventricular end-diastolic pressure.
Authors: Matsuda Y , Toma Y , Matsuzaki M , Moritani K , Satoh A , Shiomi K , Ohtani N , Kohno M , Fujii T , Katayama K
Published: June 2011

The relation between the left atrial systolic pressure waveform and left ventricular end-diastolic pressure was observed in 17 patients who underwent diagnostic cardiac catheterization. Left atrial pressure and left ventricular pressure were simultaneously recorded from a multisensor catheter before and during angiotensin infusion. Left ventricular systolic pressure and left ventricular end-diastolic pressure were 133 +/- 17 and 12.3 +/- 3.2 mm Hg, respectively, before angiotensin infusion and increased to 168 +/- 18 (p less than 0.01) and 19.4 +/- 4.5 mm Hg (p less than 0.01), respectively, during infusion. The left atrial systolic pressure curve consisted of two positive waves--a first wave (A) and a second wave (A'). The A and A' wave pressures were 11.6 +/- 2.3 and 10.2 +/- 3.9 mm Hg, respectively, before angiotensin infusion and 16.5 +/- 2.9 (p less than 0.01) and 18.1 +/- 4.7 mm Hg (p less than 0.01), respectively, during infusion. The ratio of A'/A of left atrial systolic pressure was 0.81 +/- 0.27 before angiotensin infusion and 1.08 +/- 0.14 (p less than 0.01) during infusion. The ratio of A' to A of left atrial systolic pressure was linearly related to left ventricular end-diastolic pressure before and during (p less than 0.01) angiotensin infusion. The amplitude of the A wave exceeded that of the A' wave at normal left ventricular end-diastolic pressures. However, as the left ventricular end-diastolic pressure increased either at rest or during angiotensin infusion, the amplitude of the A' wave increased and often exceeded that of the A wave. These results suggest that the second (A') wave might be attributed to the increased reflection associated with increased left ventricular end-diastolic pressure.
Prognostic value of electrophysiology testing in asymptomatic patients with Wolff-Parkinson-White pattern.
Authors: Leitch J W , Klein G J , Yee R , Murdock C
Published: June 2011

The prognostic value of electrophysiology testing was studied in 75 asymptomatic patients with the Wolff-Parkinson-White electrocardiographic pattern. All patients underwent electrophysiology testing at entry to the study and were followed up annually for a total of 348 patient-years (median, 4.3 years). There were 44 male and 31 female patients, and age at enrollment ranged from 7 to 77 years (mean, 34 +/- 14 years). The median effective refractory period of the accessory pathway was 293 msec (interquartile range, 280-310 msec), and the median shortest RR interval between preexcited beats during atrial fibrillation (SRR) [corrected] was 274 msec (240-320 msec). Twenty-three patients had an SRR of 250 msec or less and eight patients had a median shortest SRR interval of 200 msec or less. Twelve patients had inducible sustained reciprocating tachycardia, 10 patients had inducible nonsustained reciprocating tachycardia, and 23 patients had inducible sustained atrial fibrillation. Twenty patients (27%) lacked retrograde conduction over the accessory pathway. No patient died suddenly during a median follow-up of 4.3 years. Six patients (8%) became symptomatic with documented supraventricular tachycardia, of whom two underwent operative ablation of their accessory pathways. No patient with absent retrograde accessory pathway conduction during the electrophysiology study became symptomatic. Inducible sustained or nonsustained reciprocating tachycardia at electrophysiology study did not predict the development of subsequent symptomatic supraventricular tachycardia. Nine patients lost preexcitation during follow-up. Age at enrollment (relative risk/decade, 1.4; 95% confidence interval, 1.0-1.8) and anterograde accessory pathway refractory period (relative risk, 1.06/10 msec; 95% confidence interval, 1.0-1.12) were independent predictors of loss of preexcitation.(ABSTRACT TRUNCATED AT 250 WORDS)
Effect of tachycardia on regional function and transmural myocardial perfusion during graded coronary pressure reduction in conscious dogs.
Authors: Canty J M , Giglia J , Kandath D
Published: June 2011

The purpose of the present study was to examine subendocardial flow and function during graded coronary pressure reduction to determine the effect of tachycardia on the lower autoregulatory pressure limit (critical coronary pressure) in unanesthetized dogs. During atrial pacing at a rate of 200 beats/min, subendocardial flow measured by radioactive microspheres averaged 1.55 +/- 0.34 ml/min/g and remained unchanged as pressure was reduced over the autoregulatory plateau from 84 +/- 10 to 59 +/- 7 mm Hg. Further reductions in coronary pressure to below a critical coronary pressure of approximately 60 mm Hg were associated with concomitant reductions in subendocardial flow and the endocardial-epicardial flow ratio during tachycardia. Although regional function remained constant over the autoregulatory plateau, there was a rightward shift of the coronary pressure-function relation during ischemia in response to a steady-state increase in rate from 100 to 200 beats/min. Reductions in regional wall thickening began when coronary pressures reached 38 +/- 7 mm Hg at a heart rate of 100 beats/min and 61 +/- 6 mm Hg at a heart rate of 200 beats/min (p less than 0.005). Similar critical coronary pressure values were obtained for subendocardial segment shortening. Relations between subendocardial flow and myocardial function measured by both transmural wall thickening and subendocardial segment shortening were linear during pacing at a heart rate of 200 beats/min with relative reductions in wall thickening related to reductions in subendocardial flow on a nearly one-to-one basis. The results of this study demonstrate that there is a shift in the lower limit of subendocardial autoregulation during tachycardia as manifest by the onset of subendocardial ischemia at a higher distal coronary artery pressure. The shift in critical coronary pressure relates to an increase in resting flow requirements due to increased demand and diminished subendocardial vasodilator reserve at any given coronary pressure secondary to a reduction in the time available for diastolic subendocardial perfusion during tachycardia.
Effect of epinephrine and lidocaine therapy on outcome after cardiac arrest due to ventricular fibrillation.
Authors: Weaver W D , Fahrenbruch C E , Johnson D D , Hallstrom A P , Cobb L A , Copass M K
Published: June 2011

One hundred ninety-nine patients with out-of-hospital cardiac arrest persisted in ventricular fibrillation after the first defibrillation attempt and were then randomly assigned to receive either epinephrine or lidocaine before the next two shocks. The resulting electrocardiographic rhythms and outcomes for each group of patients were compared for each group and also compared with results during the prior 2 years, a period when similar patients primarily received sodium bicarbonate as initial adjunctive therapy. Asystole occurred after defibrillation with threefold frequency after repeated injection of lidocaine (15 of 59, 25%) compared with patients treated with epinephrine (four of 55, 7%) (p less than 0.02). There was no difference in the proportion of patients resuscitated after treatment with either lidocaine or epinephrine (51 of 106, 48% vs. 50 of 93, 54%) and in the proportion surviving (18, 19% vs. 21, 20%), respectively. Resuscitation (64% vs. 50%, p less than 0.005) but not survival rates (24% vs. 20%) were higher during the prior 2-year period in which initial adjunctive drug treatment for persistent ventricular fibrillation primarily consisted of a continuous infusion of sodium bicarbonate. The negative effect of lidocaine or epinephrine treatment was explained in part by their influence on delaying subsequent defibrillation attempts. Survival rates were highest (30%) in a subset of patients who received no drug therapy between shocks. We conclude that currently recommended doses of epinephrine and lidocaine are not useful for improving outcome in patients who persist in ventricular fibrillation.(ABSTRACT TRUNCATED AT 250 WORDS)
Indium-111-monoclonal antimyosin antibody studies after the first year of heart transplantation. Identification of risk groups for developing rejection during long-term follow-up and clinical implications.
Authors: Ballester M , Obrador D , Carrió I , Augé J M , Moya C , Pons-Lladó G , Caralps-Riera J M
Published: June 2011

The long-term clinical course and results of biopsies in 21 patients studied with monoclonal antimyosin antibodies more than 12 months after heart transplantation according to the presence and degree of antimyosin-antibody uptake is described. Eighteen men and three women aged 20-52 years (39 +/- 9 years) were studied with antimyosin antibodies 12-40 months (mean, 22 +/- 9 months) after heart transplantation, and followed for a mean of 18 months (10-28 months). The number of biopsies performed during follow-up was 102. Results showed normal antimyosin-antibody studies in nine patients and abnormal studies in 12 patients. Myocyte damage was identified in 18 of the 102 biopsies (17.6%), one in the normal antimyosin-antibody group of patients and 17 in those patients with myocardial antimyosin-antibody uptake. Patients who developed rejection comprised 11% and 67% of each respective group; the mean number of rejection episodes per patient was 0.11 +/- 0.33 and 1.41 +/- 1.41, respectively (p less than 0.01). A trend was noted by which higher heart-to-lung ratios were associated with greater probability of rejection. Conclusively, 1) antimyosin-antibody studies performed after more than 1 year after heart transplantation indicate the presence and level of rejection activity, 2) groups of patients at risk for developing rejection at biopsy during long-term follow-up may be detected by antimyosin-antibody study, and 3) surveillance for rejection and the degree of immunosuppression should be tailored to meet individual patient needs.
Effect of nontransmural necrosis on epicardial potential fields. Correlation with fiber direction.
Authors: Watabe S , Taccardi B , Lux R L , Ershler P R
Published: June 2011

The effect of nontransmural necrosis on epicardial potential distributions was studied in 13 dogs. In previous studies, left ventricular epicardial pacing generated epicardial potential maps at QRS onset with a negative central area and two positive areas that faced the portions of the wavefront propagating along fibers. Subsequently, the positive areas expanded in a counterclockwise direction by 90 degrees to 120 degrees. In those studies, the rotatory expansion of the positive areas was tentatively attributed to the spread of excitation through deep myocardial layers, where fiber direction rotated counterclockwise from epicardium to endocardium. To test this hypothesis, we tried to interrupt the counterclockwise expansion of the positive area by creating localized, nontransmural necrosis at various depths in the left ventricular wall by injection of formalin or application of laser energy. Epicardial potential maps were obtained from a grid of 12 x 15 electrodes on a 44 x 56-mm area. Epicardial pacing from selected sites generated epicardial maps in which some positive areas were missing compared with controls. The direction of the straight line joining the pacing site to the site of missing positivity correlated well with the average fiber direction in the necrotic mass (r = 0.82, p less than 0.01). Angle between epicardial fiber direction and the straight line described above correlated well with the average depth of the necrosis, expressed as percent of the wall thickness (r = 0.95, p less than 0.01). These data support the hypothesis that the counterclockwise expansion of the epicardial positivity occurring after epicardial pacing results from excitation spreading along deep fibers.(ABSTRACT TRUNCATED AT 250 WORDS)
Bleeding time prolongation with streptokinase and its reduction with 1-desamino-8-D-arginine vasopressin.
Authors: Johnstone M T , Andrews T , Ware J A , Rudd M A , George D , Weinstein M , Loscalzo J
Published: June 2011

The mechanism by which treatment with thrombolytic agents causes bleeding is not known. Recently, frequency of bleeding events has been shown to correlate with bleeding time, particularly in individuals treated with aspirin. We examined the effects of streptokinase (20,000-60,000 IU/kg) on bleeding time in 40 rabbits pretreated with aspirin, a model for fibrinolytic therapy. We then tested the effects of 1-desamino-8-D-arginine vasopressin (DDAVP) (0.3 microgram/kg), an agent known to reduce bleeding time in a variety of bleeding disorders, in 20 rabbits and compared the results with those of a control group of rabbits receiving normal saline placebo. Aspirin increased the bleeding time from a baseline mean +/- SEM value of 119 +/- 15 to 191 +/- 34 seconds in the control group and from 114 +/- 6 to 188 +/- 18 seconds in the experimental group. The addition of streptokinase increased the bleeding time to 592 +/- 119 seconds in the control group and 810 +/- 114 seconds in the experimental group (p = NS). Subsequent infusion of DDAVP decreased the bleeding time in the experimental group to 302 +/- 29 seconds (p less than 0.01 versus streptokinase) compared with 572 +/- 79 seconds (p = NS versus streptokinase) in the control animals given saline placebo. In a subset of rabbits receiving aspirin and streptokinase (40,000-60,000 IU/kg), samples were obtained for platelet aggregation (n = 16), von Willebrand factor antigen concentration (n = 17), and von Willebrand factor multimer distribution (n = 14). Maximal rates of ADP-induced platelet aggregation were not affected by DDAVP infusion, nor was the plasma concentration of von Willebrand factor antigen, quantified by an immunoradiometric assay, significantly affected by DDAVP infusion. Furthermore, the von Willebrand factor multimer ratio decreased with DDAVP administration. These findings indicate that aspirin and streptokinase combined result in a marked increase in bleeding time that can be reduced by DDAVP. This effect of DDAVP is not accompanied by an increase in platelet aggregation response, plasma von Willebrand factor antigen concentration, or von Willebrand factor multimer ratio.
Wenckebach periodicity in single atrioventricular nodal cells from the rabbit heart.
Authors: Hoshino K , Anumonwo J , Delmar M , Jalife J
Published: June 2011

Previous studies have suggested that Wenckebach periodicity in cardiac tissues may occur because of discontinuous propagation across junctional areas in which there is high intercellular resistivity or different cell types. Under these conditions, the impulse may stop altogether at a given junction, or may renew its propagation but only after a step delay imposed by the diastolic time-dependent recovery in the excitability of cells distal to that junction. Accordingly, Wenckebach periodicity in the atrioventricular node may be explained in terms of electrotonically mediated delay in the activation of the nodal cells. To test this hypothesis, we have studied recovery of excitability, and susceptibility to rate-dependent activation failure in single myocytes isolated from the adult rabbit atrioventricular node. Recordings were obtained by using the patch technique in the whole-cell, current clamp configuration. Repetitive stimulation of single atrioventricular nodal myocytes with depolarizing current pulses of critical amplitude yielded frequency-dependent stimulus response patterns that ranged from 1:1, through various Wenckebachlike periodicities (e.g., 5:4 and 4:3) to 2:1 and 3:1. Both typical and atypical Wenckebach structures were demonstrated, as well as "complex" patterns (e.g., reverse Wenckebach or alternating Wenckebach) previously ascribed to multiple levels of block. The diastolic recovery of excitability curve, determined by application of repetitive stimuli at cycle lengths that were longer than the action potential duration, showed a monotonic function with a refractory period outlasting the action potential duration (i.e., postrepolarization refractoriness). Abbreviation of the stimulation cycle length to values below those of the action potential duration revealed the existence of a period of supernormal excitability during the repolarizing phase of the action potential. In either case, the stimulus response patterns obtained were a direct consequence of the shape of the recovery of excitability curve. The monotonic portion of the recovery curve was fitted to an empirical equation that when iterated reproduced the stimulus response patterns observed in the atrioventricular nodal cell. Our data demonstrate that recovery of excitability after an action potential is indeed a function of the diastolic interval, and that this slow process sets the conditions for the development of Wenckebach periodicity in the atrioventricular node.
Fibrinopeptide A is released into the coronary circulation after coronary spasm.
Authors: Oshima S , Yasue H , Ogawa H , Okumura K , Matsuyama K
Published: June 2011

To examine whether acute myocardial ischemia activates the coagulation system and platelet activation in the coronary circulation, we measured plasma levels of fibrinopeptide A and beta-thromboglobulin in the coronary sinus and the aortic root simultaneously in 15 patients with coronary spastic angina before and after the left coronary spasm induced by intracoronary injection of acetylcholine and in 15 patients with stable exertional angina before and after acute myocardial ischemia induced by rapid atrial pacing. Fifteen patients with chest pain but normal coronary arteries and no coronary spasm served as controls. The coronary sinus-arterial difference of fibrinopeptide A increased markedly (p less than 0.001) from 0.1 +/- 0.2 to 4.3 +/- 0.7 ng/ml after the anginal attacks in the coronary spastic angina group. However, fibrinopeptide A levels remained unchanged after the attacks in the stable exertional angina group and after intracoronary injection of acetylcholine in the control group. Plasma beta-thromboglobulin levels remained unchanged after the attacks in both patient groups and after acetylcholine in the control group. Our data indicate that coronary spasm induces thrombin generation and may lead to thrombus formation in the coronary artery involved, but pacing-induced ischemia does not activate the coagulation system.
Retrieval of a Thrombus Attached to a Cournand Needle
Authors: DYLL LOUIS M. , DYLL JAMES W. , SPEER ROBERT J.
Published: June 2011

Upon completion of a carotid angiogram, a clot of platelets, leukocytes, erythrocytes and fibrin was found attached to a No. 18 gauge Cournand needle. The chance retrieval of this thrombus establishes the occurrence of thrombus formation on angiographic needles. Such thrombi could be the source of some post-angiographic infarctions and are consistent with current concepts of clotting.
Protective Effects of Acetazolamide and Hyperbaric Oxygenation on Experimentally Induced Syncope
Authors: KONG YIHONG , LUNZER STEVEN , HEYMAN ALBERT , SALTZMAN HERBERT A.
Published: June 2011

The protective effects of acetazolamide and hyperbaric oxygenation on experimentally induced syncope were evaluated in seven healthy male subjects. Syncope was induced by vigorous hyperventilation and Valsalva maneuver. Each subject performed these procedures three times in each of the following conditions: (1) breathing room air at normal atmospheric pressure, (2) breathing 100% oxygen at 2.36 atmospheric pressure, (3) breathing 9% oxygen at 2.36 atmospheres and (4) after intravenous injection of 500 mg of acetazolamide while breathing 100% oxygen at 2.36 atmospheres. With comparable changes of arterial pCO
2
and blood pressure during the hyperventilation-Valsalva maneuver, syncope occurred in 19 of 21 (91%) hyperventilation-Valsalva maneuvers performed at ambient environment, in 18 of 21 (86%) when subject was breathing 9% oxygen at 2.36 atmospheres, in 14 of 21 (67%) when 2.36 atmospheres of 100% oxygen was used, and in only 7 of 21 (33%) when acetazolamide was used in conjunction with hyperbaric oxygen. Syncope was completely prevented by hyperbaric oxygenation in one subject and by the combination of acetazolamide and hyperbaric oxygen in four subjects. These studies demonstrate that cerebral vasodilation induced by acetazolamide combined with increased oxygen delivery to the brain resulting from hyperbaric oxygenation may preserve cerebral function during the period of hypotension and hypocapnia produced by hyperventilation and Valsalva maneuver.
Recurrent Atherosclerotic Obstruction of the Internal Carotid Artery Five Years After Endarterectomy
Authors: HEYMAN ALBERT , BROWN IVAN W. , CAMPLONG LINDA , UTLEY CAROL
Published: June 2011

A patient is described in whom an obstructive atherosclerotic plaque recurred in the cervical portion of the internal carotid artery five years after endarterectomy. The lesion appeared to be a new formation of atheromatous material contiguous to the site of the previous arteriotomy and resulted in neurological symptoms almost identical to those experienced by the patient five years before.

This case suggests that the treatment of cerebral ischemia by surgical removal of stenotic lesions in the extracranial cerebral arteries may produce only temporary relief of symptoms and emphasizes the need, following endarterectomy, for medical therapy of the underlying atherosclerotic disease.
Death Statistics for Cerebrovascular Disease: A Review of Recent Findings
Authors: WYLIE CHARLES M.
Published: June 2011

There is a large margin of error in death statistics. Mortality statistics for cerebrovascular disease show, however, the well-known rise in frequency with age, the higher frequency in men than women which is likely to affect all countries in the coming years, and the greater involvement of nonwhite Americans and Japanese than of white Americans and Japanese Americans. I believe that incidence figures, when they become available in future years, will confirm these findings. Environmental factors, such as a "water factor," also relate to cerebrovascular death rates. Possibly the biggest factor in the medical environment, causing artificial swings in both mortality and incidence figures, will be shown to be the changing diagnostic habits of physicians.

From the viewpoint of etiology, the coexistence of hypertension and cerebrovascular disease dominates the epidemiological picture. The geographic distribution of cerebrovascular mortality in the U.S.A., and the higher mortality in Negroes and in the elderly, particularly relate to underlying hypertension. Ongoing and future population studies, focusing on morbidity as well as mortality, are likely to contribute much in clarifying the relative importance of other causal factors whose harmful effects can be controlled.
Experimental Subarachnoid Hemorrhage: A Study for Spasm with the Production of Aneurysms
Authors: ROY VANCE C. , SUNDT THORALF M. , MURPHEY FRANCIS
Published: June 2011

We have shown the difficulty in producing a reliable model of vasospasm secondary to recurrent subarachnoid hemorrhage from carotid puncture in a squirrel monkey. In this animal, mild systemic hypertension had little or no effect on the clinical status after hemorrhage. The consistent production of a saccular aneurysm on the intracranial arteries was an unexpected result of the arterial puncture and the interruption of the internal elastic membrane. At this time, there is insufficient knowledge regarding the entire subject of vasospasm for correlation with human vessel reaction to injury.
Cerebral Blood Flow and Internal Carotid Artery Flow During Carotid Surgery
Authors: BOYSEN GUDRUN , LADEGAARD-PEDERSEN H. J. , VALENTIN N. , ENGELL H. C.
Published: June 2011

In a series of 17 patients operated on for stenosis of the internal carotid artery, measurement of the blood flow in the internal carotid artery by a squarewave electromagnetic flowmeter was performed simultaneously with measurement of the regional cerebral blood flow (rCBF) by the
133
Xenon injection technique. The measurements were made before and after endarterectomy. On completion of endarterectomy there was significant increase in mean internal carotid artery flow (ICAF), from 133 ml/min to 212 ml/min (P<0.05), whereas mean rCBF remained unaltered.

The ratio ICAF/rCBF gives brain substance in grams supplied by the internal carotid artery. The mean value of this ratio increased significantly from 231 gm to 452 gm after endarterectomy (P<0.01). Thus cerebral hemodynamics tended to the normal postoperatively.
Blood Volume, Hematocrit and Pressure Relationships in the Isolated Perfused Dog Brain
Authors: LEVIN VICTOR A. , GILBOE DAVID D.
Published: June 2011

The intracranial blood volume and hematocrit of the isolated perfused dog brain preparation were determined with Cr
51
-labeIed erythrocytes. The intracranial blood volume was determined to be 8.6 ml/100 gm brain (SE±1.2 ml). Over the range of perfusing hematocrits studied, the relationship of perfusing hematocrit (Hct
PR
) to intracranial hematocrit (Hct
IC
) was found to be a linear function (Hct
IC
= 5.44 + 0.702 Hct
PR
). At a peripheral hematocrit of 20% the Hct
IC
/Hct
PR
≈ 1.0, whereas at hematocrits of 50 to 55% this ratio dropped to 0.87.

With increasing perfusing hematocrits the carotid artery pressure rose markedly and there was flattening of the EEG. Since the isolated dog brain is a closed system void of extracranial anastomoses, high viscosity blood cannot circumvent the cerebral circulation but must follow the high resistance networks of the deep cerebral vasculature until sludging of the erythrocytes becomes sufficient to cause anoxia and loss of autoregulation. In the intact erythrocythemic animal, however, increases in arteriolar pressure can be reflected downstream to the large cerebral and meningeal vessels with extracranial shunting of high hematocrit (high viscosity) blood from the brain.
Hypertension Complicating Carotid Endarterectomy
Authors: LEHV MICHAEL S. , SALZMAN EDWIN W. , SILEN WILLIAM
Published: June 2011

Fifteen of 27 patients became hypertensive after unilateral carotid endarterectomy; seven of these experienced neurological deterioration, which persisted more than a week in five patients. Neurological worsening did not occur in patients without postoperative hypertension, which developed primarily in patients with a preoperative disturbance of consciousness or other neurological deficit, especially in those with seizure activity. There was no correlation with preoperative blood pressure, the time of arteriography, arteriographical or operative findings, use of an internal shunt, or other features of operative or anesthetic technique. Serum sodium concentration was significantly lower in hypertensive patients, although fluid administration did not vary in the two patient groups.
The Effect of Isordil and Cyclospasmol on Vascular Spasm Induced in the Basilar Artery of the Cat
Authors: MAHALEY M. S. , KAPP JOHN
Published: June 2011

Vasospasm of the basilar artery of the cat was induced by subarachnoid bleeding and was observed by a transoral approach to the vessel. Intravenous Isordil (2 to 4 mg/kg) given following vasospasm produced vasodilatation with minimal arterial hypotension. Cyclospasmol, administered intravenously after vasospasm or orally prior to vasospasm, was ineffective in relieving or preventing basilar artery spasm.
The Relation Between Cardiac Function and Cerebral Blood Flow in Stroke Patients. 1. Effect of CO
2
Inhalation
Authors: COOPER EDWARD S. , WEST JAMES W. , JAFFE MARVIN E. , GOLDBERG HERBERT I. , KAWAMURA J. , MCHENRY LAWRENCE C.
Published: June 2011

The effects of CO
2
inhalation were determined on 23 stroke patients with and without hypertension who underwent clinical, cardiohemodynamic, cerebral blood flow (hemispheric mean and regional), cerebral metabolic rate and cerebral angiographical studies.

Cardiac output, heart rate, systemic and pulmonary arterial blood pressures and cardiac work rose in essentially all patients during CO
2
inhalation, and fell to below baseline levels in approximately half of the patients studied after CO
2
, inhalation was discontinued.

Baseline cardiac output was normal in normotensive stroke patients without cardiac dysfunction, but was low in hypertensive stroke patients.

A statistically significant increase in cerebral blood flow occurred during CO
2
, inhalation, with an observed decrease in cerebrovascular resistance. The percentage increase in cerebral blood flow exceeded the increase in cardiac output.

Since hypercarbia causes a rise in systemic and pulmonary arterial blood pressure, CO
2
inhalation should be used cautiously in patients with systemic or pulmonary hypertension. The rise in cardiac work during CO
2
inhalation could jeopardize patients with coronary heart disease and those with heart failure.

Following cessation of CO
2
inhalation, blood pressure and cardiac output may fall below baseline levels, with a risk of posthypercapnic fall in cerebral blood flow. Occasionally, cardiac arrhythmia occurs during or following CO
2
inhalation.
Bilateral Jugular Venous Blood Flow by Thermal Dilution
Authors: WILSON EDWIN M. , HALSEY JAMES H.
Published: June 2011

Measurements of internal jugular venous flow were made in 12 patients with severe cerebral vascular disease. Flow rates were determined by the thermal dilution method, using room temperature physiological (heparinized) saline as an indicator infused at a constant rate. The major sources of error (indicator mixing) were studied under highly controlled in vitro experiments. Total jugular venous outflow was substantially below mean values of total cerebral flow for normal subjects and somewhat below the mean values for demented patients. Free communication between the two jugular veins via the torcular was observed in all patients. Following unilateral venous compression, the differential shift to the contralateral vein was not always equal to the precompression total flow. This would seem to indicate that this maneuver produces some diversion of flow to other venous channels and suggests that total cerebral blood flow can be obtained reliably only through bilateral measurements.
A Method for Measuring Cerebral Hemispheric Blood Flow and Metabolism
Authors: MEYER JOHN STIRLING , SHINOHARA YUKITO
Published: June 2011

A new method for measuring cerebral hemispheric blood flow together with metabolism using an injection of a 5 ml bolus of hydrogen-saturated saline into each internal carotid artery is described. This method was extensively evaluated in the monkey prior to being used in man.

Under fluoroscopic control, a catheter was inserted into each cerebral transverse sinus via the basilic veins. Hemispheric blood flow was calculated from the clearance curves of hydrogen from the transverse sinus following injection using a formula based upon the Stewart-Hamilton principle. Hemispheric metabolic index for oxygen was estimated using a new formula by assuming that the distribution of hydrogen into each transverse sinus following injection of the bolus indicates the distribution of the blood from each hemisphere into each transverse sinus.

This method has certain advantages over the conventional method for measuring cerebral blood flow, since the actual geometry of the brain in which the blood flow measured is known and simultaneous estimations of hemispheric metabolism are possible.

Abnormalities of hemispheric blood flow and metabolism have been measured in 30 patients suffering from various neurological disorders including occlusion of one internal carotid artery.

The new formula for estimating hemispheric metabolism is applicable to radioisotopic and other indicator injection methods in which blood is sampled from the cerebral transverse sinuses or internal jugular veins.

It was also shown that the transverse sinus distribution of blood derived from each cerebral hemisphere varies from one individual to another.
Age: Its Significance in Nonembolic Cerebral Infarction
Authors: LOUIS SYDNEY , MCDOWELL FLETCHER
Published: June 2011

The frequency of occurrence of nonembolic cerebral infarction is linearly related to age.

The sexual frequency of nonembolic cerebral infarction is directly related to the age group of the sample studied.

The mortality of nonembolic cerebral infarction and its prognosis are most closely related to the age of the patient at the time of stroke. The older the patient, the higher is the mortality and the poorer the prognosis.

The cause of death in nonembolic cerebral infarction is as much a function of age-related concurrent diseases, especially cardiac disease, as it is of stroke itself. The natural history of stroke is more related to the natural history of cardiac disease than it is to cerebral vascular disease.

These data may be viewed as lending support to the thesis that nonembolic cerebral infarction and the diseases that are frequently found with it, such as diabetes, cardiac disease and hypertension, are related in their occurrence and mortality to aging and may truly be concurrent events and not etiologically related one to the other.
Effect of dextran on cerebral function and blood after cardiac arrest. An experimental study on the dog.
Authors: Lin S R , O'Connor M J , King A , Harnish P , Fischer H W
Published: June 2011

EEG activity and regional cerebral blood flow were monitored during 5 hour survival following cardiac arrest in 32 pentobarbital anesthetized mongrel dogs. The animals were mechanically ventilated and blood gases were maintained at physiologic levels. Regional cerebral blood flow and cardiac output were measured using 15 mu microspheres. EEG was recorded from 6 epidural electrodes using bipolar techniques. The animals were divided into 3 groups. The animals in Group I had an arrest of 8-11 minutes and those in Group II and III had an arrest of 12-16 minutes. Group II animals received no treatment. Group III animals were given 1 g/kg of dextran 40 at a concentration of 10% in normal saline following the arrest and maintained with 10 mg/kg/min during the 5 hours of recovery. In Groups I and III there was shorter duration of a flat EEG and 5 hours after the arrest the EEG activity was closer to normal than in Group II. After 5 hours the EEG scores of Group III were significantly greater than Group II (p less than 0.03). The cortical grey matter and hippocampus had the greatest reduction of blood flow following cardiac arrest. The mean cortical grey matter blood flow in Group II was less than in Groups I and III at 3 hours. After 5 hours the grey matter blood flow was greater in Group III than in Group II (p less than 0.09). The findings of this study are consistent with the hypothesis that after cardiac arrest perfusion abnormalities persist or develop after return of blood pressure and that these can be corrected or prevented with improved functional survival by treatment with dextran 40 after the arrest.
The disability oriented rehabilitation unit--a major factor influencing stroke outcome.
Authors: Feigenson J S , Gitlow H S , Greenberg S D
Published: June 2011

Many investigators have analyzed the effectiveness of the cardiac care unit (as a model of a disability oriented, specially staffed, geographically isolated unit) in altering outcome following acute myocardial infarction. Little data are available, however, on the efficacy of caring for patients with stroke on specially staffed disability oriented units. Of 667 patients with stroke recently discharged from the Burke Rehabilitation Center, 589 were admitted to the stroke unit (SU group) and 78 were admitted to other units (NSU group). Statistical analysis showed that the SU patients were significantly weaker, had longer onset-admission intervals, and exhibited more concurrent medical problems and neurologic deficits. There were no statistically significant intergroup differences in age, sex, and distribution of weakness. Both groups had similar treatment programs provided by staff who had rotated through the stroke unit. Ability to perform activities of daily living (dressing, feeding, hygiene, bowel and bladder routines) and length of hospitalization were similar for both groups. SU patients walked better and went home more frequently than NSU patients. These data indicate than even in a rehabilitation center specializing in treating functional disabilities, patients with stroke are more likely to improve if placed on a disability oriented unit than if they are admitted to mixed disability units which are scattered throughout the hospital.
Physostigmine-induced cerebral protection against hypoxia.
Authors: Scremin A M , Scremin O U
Published: June 2011

Physostigmine, at 0.1, 0.2 and 0.3 mg/kg, was tested for effect on the survival of mice exposed to 5% O2-95% N2. Some treated animals survived for one hour under the hypoxic atmosphere (2 out of 14 at 0.1 mg/kg and 8 out of 28 at 0.2 and 0.3 mg/kg), an event never observed in untreated controls. The physostigmine-treated animals that died before the hour showed a dose-related increase in survival time from 4.3 min (untreated controls) to 27.6 min (0.3 mg/kg physostigmine). The effect of physostigmine may be related to its reported ability to increase cerebral blood flow and decrease cerebral oxygen consumption
Neurologic and cardiovascular effects of hypotension in the monkey.
Authors: Selkoe D J , Myers R E
Published: June 2011

Thirty monkeys were exposed to controlled systemic hypotension of different magnitudes and duration to determine factors leading to brain injury or cardiovascular failure. Fourteen monkeys developed brain injury. Of these, 6 survived indifinitely and 8 were sacrificed or died within 12-62 hours due to neurologic deterioration accompanied by respiratory failure. Sixteen animals did not develop brain injury, but 9 of these died within 24 hours from documented cardiovascular failure with the remaining 7 survived indefinitely. A highly reproducible threshold for the development of brain injury was found at a mean arterial blood pressure (MABP) of 25 mm Hg. Maintenance MABP was less than or equal to 25 mm Hg in 13 of 14 lesioned monkeys and greater than 25 mm Hg in 15 of 16 non-lesioned monkeys. Maintenance MABP averaged 20.1 +/- 1.1 mm /g in lesioned and 32.1 +/- 1.7 mm Hg in non-lesioned animals (p less than 0.001). Among the non-lesioned animals, death from delayed cardiovascular failure ensued when MABP was maintained between 27 and 35 mm Hg for 90 min or longer. Animals exposed to this range of hypotension for less than 90 min or to MABP exceeding 35 mm Hg for as long as 3 h survived intact. EEG changes occurring during hypotension most accurately predicted neurologic outcome. The threshold MABP required to produce cerebral electric silence was 21-22 mm Hg. Monkeys developing marked brain injury had greater than 25 minutes of EEG flattening, while slightly injured animals had it for 5-15 minutes and those without injury for less than 5 min. Changes in acid-base state, common carotid artery blood flow, and cerebral uptake of glucose and oxygen during hypotension also correlated with neurologic and cardiovascular outcome. Hypoxemia and hypercarbia were not contributory factors in the production of brain injury in this study.
Extracorporeal glass-wool filtration of whole blood enhances post-ischemic recovery of the cortical sensory evoked response.
Authors: Hallenbeck J M , Furlow T W , Ruel T A , Greenbaum L J
Published: June 2011

In twenty dogs, anticoagulated with heparin 300 units/kg, the right cortical sensory evoked response (CSER) to contralateral median nerve stimulation was suppressed during 60 min ischemia induced by periodic infusion of 50 to 100 microliter increments of air via the right internal carotid artery. The post-ischemic recovery of the CSER was followed an additional 60 min in 19 of these animals divided into 2 groups. Ten dogs were subjected to glass-wool filtration of their blood by extracorporeal shunting from femoral artery to femoral vein for one hr prior to infusing air. Nine dogs did not receive glass-wool filtration. Post-ischemic recovery of CSER amplitude, a quantifiable electrophysiologic index of neuronal function, was significantly greater in the filtered group than in the non-filtered group. 14C-antipyrine autoradiographic blood flow studies were performed in 3 dogs. One was studied at the end of a 60 min ischemic CSER suppression period and showed severe flow disruption by air embolism. Two dogs, one from each group, were studied at the conclusion of the 60 min recovery period. In the filtered animal, cortical blood flow exceeded the threshold for CSER maintenance while cortical flow rates in the unfiltered animal fell below this threshold. The enhanced postischemic neuronal recovery in the filtered group as indicated by the CSER in attributed to the preservation of injury zone nutrient blood flow that is supported by collateral circulation.
Influence of sex on cerebral ischemia following bilateral carotid occlusion in spontaneously hypertensive rats: a metabolic study.
Authors: Nakatomi Y , Fujishima M , Tamaki K , Ishitsuka T , Ogata J , Omae T
Published: June 2011

Cerebral lactate, pyruvate and adenosine triphosphate (ATP), and acid-base balance were measured in male and female spontaneously hypertensive rats (SHR) before, and 1, 3 and 5 hours after bilateral carotid occlusion. In male SHR, cerebral lactate and the lactate/pyruvate (L/P) ratio progressively increased after occlusion, while cerebral ATP decreased. In female SHR, an increase in lactate and the L/P ratio was less marked than in male SHR. Cerebral ATP remained unchanged 5 hours after occlusion. These data suggest that bilateral carotid artery occlusion may cause more pronounced ischemic changes in the brain in male SHR than in female SHR, resulting in a greater increase in lactate with a concomitant decrease in ATP in male SHR. Results suggest that female SHR are more resistant to cerebral ischemia following bilateral carotid occlusion than male SHR. Blood pressure and gonads in the susceptibility to cerebral ischemia are discussed.