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At least 235 records · Page 13Linked to original sources
PubMed1998

Hemodynamics of ophthalmic artery and central retinal artery and correlation with other factors in patients with primary open angle glaucoma.

OBJECTIVE: To investigate the hemodynamics of ophthalmic artery (OA) and central retinal artery (CRA) in patients with primary open angle glaucoma(POAG) and analyse the correlation between hemodynamics of OA and CRA and other factors. METHODS: The hemodynamics of OA and CRA in normal persons (102 eyes) and glaucomatous patients (102 eyes) were measured by Colour Doppler Image (CDI). The linear correlation analysis was made between OA and CRA about each of the following parameters: the peak systolic flow velocity (Vmax), the end diastolic velocity (Vmin). The multiple stepwise regression analysis was taken to investigate the correlation between each of the following hemodynamics of OA and CRA: Vmax and Vmin in 74 eyes with POAG and each of the following related factors in hemorrheology: whole blood apparent viscosity at low, medium and high shear rate, plasma viscosity and hematocrit. The multiple linear regression was applied to investigate the correlation between each of the following hemodynamics of OA and CRA: Vmax and Vmin in 69 eyes with POAG and each of the following blood vessel filling time: the arm-retinal artery (A-AT) and retinal artery-venous (A-VT) of the fundus fluorescein angiography(FFA). RESULTS: The Vmax, Vmin and time-averaged maximum velocity (Vmean) of OA and CRA in patients with POAG were lower than those in normal persons, but the resistance index (RI) of OA and CRA was higher than those in normal. There was a positive correlation between OA and CRA in Vmin, but a negative correlation between Vmin of OA and plasma viscosity. The whole blood apparent viscosity at low shear rate was clodely related to Vmax and Vmin of CRA. Also there was a negative correlation between Vmax of CRA and A-AT of the FFA. CONCLUSION: There was abnormal hemodynamics, which is influenced by blood viscosity, of OA and CRA in patients with POAG. Abnormal hemodynamics can affect the blood supply to optic disc and retina in POAG.

Blood Flow Velocity↗
PubMed2006

Hemodynamic profile during laparoscopic cholecystectomy versus laparoscopic bariatric surgery--the impact of morbid obesity.

UNLABELLED: The present study investigated the hemodynamic profile using impedance cardiography (ICG) monitor during pneumoperitoneum for laparoscopic cholecystectomy versus bariatric surgery in order to determine the impact of body weight on hemodynamics. METHODS: 32 adult patients (two groups, each 16 patients) were studied. Group 1 (16 patients) scheduled to undergo laparoscopic cholecystectomy (lapchole) with body mass index (BMI) 28 +/- 5kg/m2. Group 2 (16 patients) scheduled to undergo laparoscopic adjustable band (LAGB) surgery for treatment of morbid obesity with BMI 45.3 +/- 8kg/m2. under general anesthesia. Besides routine monitoring, impedance cardiography was used for hemodynamic monitoring. Three stages were identified for statistical analysis A, pre-insufflation, B, during pneumoperitoneum and C, at gas deflation. RESULTS: The mean values of cardiac index in Group 1 at stages A, B and C were, 3.0 +/- 1.7, 2.5 +/- 0.5 and 2.7 +/- 0.5L/min/m2 respectively with significant low values in stage B compared to stage A (P<0.05). The same trend continue in Group 2 where the mean values were, 2.4 +/- 0.6, 1.8 +/- 0.6 and 2.3 +/- 0.9L/min/m2 respectively with significant differences compared to Group 1 mean values (P<0.05). Other hemodynamic variables showed non-significant differences (P>0.05). CONCLUSIONS: Cardiac index showed significant decreasing trend in morbid obese patients compared to nonobese, which may reflect the effect of body weight on hemodynamics. On the other hand, other hemodynamic parameters was not altered by body weight. We believe that hemodynamics should be closely monitored during laparoscopic surgery with pneumoperitoneum.

Adult↗
PubMed1990

[The hemodynamic effects of various hydroxyethyl starch solutions in heart surgery patients].

Blood conservation is gaining more and more interest because of the increasing risks involved in homologous blood transfusions. Acute normovolemic hemodilution (ANH) is becoming an established technique even in cardiac surgery patients. The "optimal" kind of volume replacement, however, is still controversial. Thus, this study was carried out to investigate the hemodynamic response of 6 different hydroxyethyl starch (HES) solutions as volume replacement. METHODS. In 60 patients undergoing elective aortocoronary bypass surgery, acute, preoperative hemodilution was performed (10 ml/kg) and HES with different concentrations, molecular weight, and substitution was infused according to a randomized sequence: 1. 6% HES 450,000/0.7; 2. 10% HES 200,000/0.5; 3. 3% HES 200,000/0.5%; 4. 6% HES 40,000/0.5; 5. 6% HES 200,000/0.5; 6. 6% HES 200,000/0.62. All patients were monitored using a new pulmonary artery catheter that allows measurement of the right ventricular ejection fraction (RVEF), right ventricular enddiastolic volume (RVEDV), and right ventricular end systolic volume (RVESV) in addition to standard hemodynamic parameters. RESULTS. Immediately after finishing ANH the typical hemodynamic changes of hemodilution (HD) were apparent (decrease in peripheral resistance and increase in cardiac index (CI]. All 6 solutions investigated were effective in hemodynamic stabilization (no changes in mean arterial pressure (MAP), filling pressures (PCP, RAP), or heart rate (HR]. Forty min after ANH, however (before beginning extracorporeal circulation (ECC], there were significant differences between the groups: in groups 3 and 4 the increase in CI had already disappeared, and SVI in group 3 was even lower than the baseline values (-8%). In the other groups, a higher CI level remained even 40 min after ANH, which was most pronounced in groups 2 (+40%) and 5 (+43%). Right ventricular performance was not changed by ANH (RVEF unchanged in all groups). Forty min after hemodilution RVEDVI (-8%) and RVESVI (-16%) decreased significantly only in group 4, whereas in the other groups these parameters were still elevated. The most pronounced positive fluid balance after the end of ECC was found in group 4 (+850 ml); in these patients paO2 decreased significantly (-150 mmHg). CONCLUSIONS. The guarantee of stable hemodynamic conditions is a prerequisite when performing ANH in coronary surgery patients. The different physiochemical attributes of various HES solutions seem to be important, thus influencing their hemodynamic response. In this study, low-concentration (3% HES 200/0.5) and low-molecular (6% HES 40/0.5) HES solutions were less effective in stabilizing hemodynamics until the beginning of ECC. Additionally, their negative influence on fluid balance during ECC, followed by a deterioration in pulmonary function led to the conclusion that other solutions are preferable; in particular, 10% HES seems to be of advantage in these situations.

Coronary Artery Bypass↗
PubMed1990

Evaluation of systemic hemodynamic effects on post-transplant perfusion to renal allograft.

Hemodynamic parameters and post-transplant renal perfusion were evaluated in 24 cadaver kidney transplantation. Cardiac output (CO), systemic vascular resistance (SVR) and mean arterial pressure (MAP), were continuously monitored in each patient via a transesophageal Doppler cardiac output monitor and radial arterial catheter. Seventeen were well perfused (Group 1) after releasing vascular clamps. Six among group 1 presented as the clinical picture of acute tubular necrosis. Seven were poorly perfused (Group 2). Post-anastomotic CO significantly increased in group 1, and decreased in group 2. SVR significantly decreased in group 1, and increased in group 2. MAP were not significantly different between group 1 and 2. Treatments based on hemodynamic derangement were initiated as soon as it was detected. Correction of CO was associated with the improvement of post-anastomotic renal perfusion, while SVR and MAP were not. Among the 7 poorly perfused kidneys, 5 became well perfused before leaving the operating room. The remaining 2 resumed their hemodynamic stability and renal function a few days later after oral captopril was administered. Two among the 6 acute tubular necrosis resumed renal function as long as hemodynamic stability was restored. Our study demonstrates that hemodynamic parameters are parallel to renal perfusion status. Restoration of hemodynamic derangement not only improves renal perfusion but also renal function. It is concluded that hemodynamic instability and graft ischemic time contribute to the variation of post-transplant perfusion to renal allograft. Non-invasive cardiac output monitor is a safe and reliable monitor which we recommend to be used during the operation of kidney transplantation.

Adult↗
PubMedDate not supplied

Evolution of hemodynamics after orthotopic heart and heart-lung transplantation: early restrictive patterns persisting in occult fashion.

Though successfully transplanted hearts respond in such a way that individuals remain remarkably asymptomatic, they do not function normally. Characterization of early hemodynamic patterns and their evolvement has not been done. The evolution of hemodynamic indices in 20 patients receiving orthotopic heart (n = 17) or combined heart-lung (n = 3) transplants is therefore documented. In 15 isolated heart recipients, right heart catheterization was performed at 24 to 48 hours, 1 to 2 weeks, 4 to 8 weeks, and greater than 3 months after surgery at the time of routine endomyocardial biopsy. Early, patients had elevated mean blood pressure (96 +/- 14 mm Hg, mean +/- standard deviation), mean right atrial pressure (15 +/- 6 mm Hg), right ventricular end-diastolic pressure (16 +/- 7 mm Hg), mean pulmonary artery pressure (30 +/- 7 mm Hg), and mean pulmonary capillary wedge pressure (19 +/- 6 mm Hg), but normal resting heart rate (96 +/- 14 beats/min) and cardiac output (5.6 +/- 1.6 L/min). Heart rate, blood pressure, and output did not change during follow-up, but right atrial pressure decreased dramatically (4 +/- 2 mm Hg at 3 months), as did right ventricular end-diastolic pressure (4 +/- 4 mm Hg), mean pulmonary artery pressure (21 +/- 8 mm Hg), and pulmonary capillary wedge pressure (11 +/- 4 mm Hg). Analysis of right heart filling dynamics revealed an abnormal inspiratory rise in mean right atrial pressure (15 +/- 6 and 27 +/- 7 mm Hg at 24 to 48 hours) that subsequently resolved. In eight patients whose resting follow-up right heart pressures normalized, rapid volume challenge uncovered occult restrictive right atrial pressure patterns that increased from 4 +/- 4 to 9 +/- 4 mm Hg after infusion of saline solution. Kussmaul's response was not apparent with prevolume infusion, but volume expansion caused appearance of this hemodynamic pattern. All patients had early evidence of tricuspid insufficiency, but in two patients, the Doppler regurgitant fraction was over 50%. These two individuals had hemodynamics similar to the other 15 patients initially, but in contrast, their right heart filling pressures did not change during follow-up. Other significant echocardiographic findings included enlarged atria and increased left ventricular mass in all patients. In two of three combined heart-lung transplant patients, similar hemodynamic patterns were evident. Rejection indices did not correlate with hemodynamic observations. Thus a characteristic evolvement of hemodynamics in heart and heart-lung transplants that mimic dynamics associated with restrictive myocardial disease is documented.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1987

[Experimental study on orthotopic liver transplantation using veno-venous bypass in the pig--the evaluation of hemodynamic alterations and the estimation of appropriate bypass flow during the period of the ahepatic state].

This is the study on the estimation of appropriate bypass flow during an hepatic phase and on hemodynamic changes in orthotopic liver transplantation. Sixty six pigs weighing 16 to 25 kg were used. Experiment I (the estimation of correct bypass flow); The relationship between bypass flow and hemodynamics was evaluated in six pigs. Bypass model without transplantation was made by following procedures. The pig liver was isolated from the blood circulation and the systemic and splanchnic venous flow was shunted to the external jugular vein via the centrifugal pump. Experiment II (the hemodynamic changes of orthotopic liver transplantation); Evaluation of hemodynamic alterations was carried out in thirty orthotopic liver transplantations. It was concluded as follows; 1. General hemodynamics such as mean arterial pressure, cardiac output, central venous pressure, pulmonary arterial pressure, etc. have not changed significantly under veno-venous bypass, however, portal and vena caval pressure elevated up to 142 and 122 percent respectively, even though the maximum bypass flow was gained. 2. Hemodynamic profile associated with the reduction of bypass flow was the same as that of acute hypovolemic shock. Immediately after the bypass was closed, mean arterial pressure and cardiac output fell down to 42 and 30% of prebypass level respectively. 3. The statistical correlationship was found between bypass flow and cardiac output (r = 0.8565). The expressions; R = (2.454 x X + 0.034)/(4.829 x X + 1.823), was induced through the correlationship between bypass flow (BF, 1/min), the maximum bypass flow (BFmax, 1/min), and cardiac output(CO, 1/min),(e.g. R = BF/CO, X = BF/BFmax). 4. Orthotopic liver transplantation was succeeded in 80% of 25 cases with stable hemodynamics. In conclusion, cardiac output . bypass flow ratio(R) was proved to be useful in orthotopic liver transplantation. A appropriate bypass flow was able to be estimated systematically using this expression.

Animals↗
PubMed1988

Right atrial isolation: a new surgical treatment for supraventricular tachycardia. II. Hemodynamic effects.

Surgical isolation of the body of the right atrium presents a unique hemodynamic situation in which the synchronous right atrial contraction (kick) is lost but the synchronous left atrial contraction is preserved. The hemodynamic effects of this procedure were evaluated by pacing at selected atrial sites postoperatively to simulate (1) sinus rhythm with a synchronous right atrial kick, (2) sinus rhythm without a synchronous right atrial kick, (3) right atrial tachycardia propagated to the entire heart (propagated right atrial tachycardia), and (4) right atrial tachycardia confined to the isolated right atrium with sinus rhythm in the rest of the heart (confined right atrial tachycardia). Hemodynamic data recorded under these four conditions showed that (1) during sinus rhythm, synchrony of right atrial contraction had no significant effect on any of the hemodynamic parameters studied and (2) conversion from propagated right atrial tachycardia to confined right atrial tachycardia resulted in an increase in mean arterial pressure (65 +/- 5 to 78 +/- 3 mm Hg, p less than 0.005) and stroke volume index (9 +/- 1 to 19 +/- 3 ml/beat/m2, p less than 0.005) with a decrease in left atrial pressure (9 +/- 2 to 5 +/- 1 mm Hg, p less than 0.05) and right atrial pressure (6 +/- 1 to 5 +/- 1 mm Hg, p less than 0.05). Moreover, cardiac hemodynamic performance remained within normal limits for up to 14 weeks. Thus the right atrial isolation procedure does not adversely affect cardiac hemodynamics despite the loss of synchronous right atrial contraction during sinus rhythm, and the procedure prevents hemodynamic deterioration during right atrial tachycardia.

Animals↗
PubMed1986

[Radiocardiographic assessment of hemodynamics in different types of acquired heart valve defects].

The hemodynamic disorders in various types of cardiac defects were studied in 133 subjects, 82 of them patients with aquired combined valvular defects of the heat and the results obtained were juxtaposed. The hemodynamics was determined by the method of quantitative radiocardiography (QRCG). The volume of circulating blood was determined as well as the indices of cardiac output, ventricular, pulmonary quantities and the indices of aortic route. The results obtained by the numerous indices followed up, juxtaposed to the separate defects, reveal hemodynamic disorders, manifested to various degrees in the various heart defects. The hemodynamic disorders in two-axis heart defects (mitral and aortic) proved to be most severe. Stroke and minute volumes were diminished. The time for filling of the right and left heart was twice prolonged. The rate of pulmonary and systematic hemodynamics was retarded two and a half times. Better manifested hemodynamic disorders advance in mitral stenosis as compared with mitral insufficient. The hemodynamic disorders in combined aortic defects proved to be the lightest.

Adolescent↗
PubMedDate not supplied

[Hemodynamic effects of a new antidepolarizing agent: fazadinium bromide].

Studies concerning the hemodynamic effects of this new antidepolarizing agent are scarce and difficult to interpret because of drug interactions, and of an accentuation of vagal tonus related to the use of morphinomimetic analgesics. For a better approach of the effects proper to fazadinium, we have tried to perform a study freed, to a maximum, from any drug interference. We studied the hemodynamic effects to a single dose of 1 mg.kg-1 of fazadinium bromide during 35 minutes in coronary patients normal hemodynamically or rhythmically, non-premedicated, ventilated with 50 p. 100 nitrous oxide in oxygen, and bebore any surgical procedure. All hemodynamic modifications are moderate and maximal 10 minutes after injection. The stroke index decreases 16 p. 100, heart rate increases 6 p. 100 and cardiac index falls 10 p. 100. Total peripheral resistance remains unchanged and mean arterial pressure drops 10 p. 100. Finally pulmonary wedge pressure decreases slightly. None of these modifications are statistically significant. One may, therefore, conclude that fazadinium tolerance, when the drug is freed from any drug interference, in coronary patients normal hemodynamically and free from rhythm disorders is excellent from a hemodynamic and rhythmic point of view. However, other isolated observations of hypovolemic subjects, or patients with atrial fibrillation receiving fazadinium and studied hemodynamically suggest a poorer tolerance in these cases.

Aged↗
PubMed1979

Hemodynamic monitoring in acute myocardial infarction.

The main cause of in-hospital death in patients with acute myocardial infarction is the "power failure syndrome". Hemodynamic monitoring provides precise and current data on the filling and output status of the left ventricle and, when indicated, the right ventricle. The information obtained is used to determine the hemodynamic status more precisely than is possible from conventional clinical assessment. It permits categorization of patients by hemodynamic status; the hemodynamic subset classification of Forrester, Diamond and Swan is a powerful tool in guiding therapy and establishing prognosis in individual patients. In addition to guiding the initiation of therapy, hemodynamic monitoring is useful in the continuing assessment of potent and complex treatment. This therapy is directed at resolving hemodynamic derangements without unfavourably altering the myocardial oxygen supply-demand relationship. Specific clinical indications for hemodynamic monitoring may include confusing or complicated clinical situations in which diagnostic problems exist, complicating mechanical derangements, severe congestive heart failure, cardiogenic shock and clinical research in acute myocardial infarction.

Acute Disease↗
PubMed1984

Effects of peroperative myocardial ischemia on early and late hemodynamic response to hypertonic sodium bicarbonate in dogs.

Because hypotension induced by the administration of hypertonic sodium bicarbonate is more severe when cardiac performance is impaired, the authors evaluated the hemodynamic consequences of peroperative myocardial ischemia upon the response of conscious dogs to an intravenous bolus of sodium bicarbonate. Twenty-two control dogs (group 1) were equipped with an electromagnetic flow probe positioned around the ascending aorta. Seventeen dogs (group 2), equipped in the same manner, were subjected to 1 hour of myocardial ischemia combined with topical cardiac hypothermia. Hemodynamic studies were performed daily for 1 month before and during the administration of sodium bicarbonate. Baseline hemodynamic values in group 1 were always within normal limits. In group 2, cardiac failure was evident in the immediate postoperative period but hemodynamic values reached normal limits 24 hours postoperatively. For both groups, the peak hypotensive response to sodium bicarbonate was combined with a substantial reduction in all hemodynamic values reflecting the left ventricular performance. However, this response is significantly (p less than 0.01) more pronounced in group 2 during the first 4 postoperative days, being maximal 3 and 24 hours after operation. Afterwards, the hemodynamic response to sodium bicarbonate was similar in both groups. These results indicated that an intravenous bolus of sodium bicarbonate decreases left ventricular performance and that this decrement is greater when cardiac performance is impaired following peroperative myocardial ischemia. Long-term hemodynamic studies show that this temporary myocardial ischemia is not deleterious to cardiovascular adaptability to hypertonic sodium bicarbonate administration.

Animals↗
PubMed1983

[Hemodynamic effects of a large dose injection of OK-432 (picibanil)].

Intratumoral administration of a large dose of OK-432 has two antitumor functions; a direct cytotoxic effect and an indirect effect through the host reticuloendotherial functions. It has been pointed out that this method, however, occasionally results in shock. Several investigators have suggested the importance of the use of general anesthesia to avoid such shock. In order to explore the hemodynamic effect of intratumoral injection of OK-432, a simulated experiment (OK-432 or saline intramuscular injection) was carried out utilizing 10 anesthetized and 10 unanesthetized dogs. In addition, hemodynamic alterations during the OK-432 administration were studied in nine patients under neuroleptal anesthesia. In both anesthetized and unanesthetized dogs, OK-432 intramuscular injection resulted in a slight decrease of the mean arterial pressure, left ventricular systolic pressure and cardiac output as compared with those of the saline injected dogs. The hemodynamic alterations, however, were minimal and were thought not to cause severe hemodynamic derangements. Clinical experiences also showed no serious hemodynamic effects by the OK-432 intratumoral injections. It was concluded that the OK-432 intratumoral injection appeared not to induce hemodynamic derangement when applied to euvolemic and hemodynamically stable patients.

Animals↗
PubMed1984

Toward a better understanding of the hemodynamic effects of protamine and heparin interaction.

Hemodynamic changes have been documented during protamine infusion into heparinized but not unheparinized pigs and suggest that a protamine-heparin interaction might be responsible. This hypothesis was tested in four groups of pigs by varying the dosage and order of administration of these two drugs: Group I (n = 9) received heparin (3 mg/kg) followed by protamine (3 mg/kg); Group II (n = 9) received protamine (3 mg/kg) followed by heparin (3 mg/kg); Group III (n = 9) received protamine (25 mg/kg) followed by heparin (3 mg/kg); and Group IV (n = 16) received protamine-heparin complex (protamine 3 mg/kg and heparin 3 mg/kg mixed immediately prior to injection). Systemic and pulmonary arterial pressures, systemic and pulmonary vascular resistances, left ventricular end-diastolic pressure, central venous pressure, cardiac output, and heart rate were measured before and at 1.0, 2.5, 5.0, and 15 minutes after protamine, heparin, or protamine-heparin complex infusions. Immediately following protamine infusion, Group I pigs exhibited transiently but significantly increased pulmonary artery pressure, pulmonary vascular resistance, systemic vascular resistance, and central venous pressure and decreased cardiac output with (Group Ib, n = 5) or without (Group Ia, n = 4) systemic hypotension. The fact that no hemodynamic changes occurred in Group II confirms that infusion of clinical doses of protamine produces no hemodynamic changes in unheparinized pigs. Protamine alone in high doses (Group III) produced hemodynamic changes similar to clinical-dose protamine reversal of heparin (Group I). This effect suggests that the presence of heparin in the circulation lowers the threshold for protamine-mediated hemodynamic responses. Infusion of heparin (3 mg/kg) into pigs 15 minutes after treatment with high (25 mg/kg) (Group III) but not clinical (3 mg/kg) (Group II) doses of protamine produced hemodynamic effects similar to clinical-dose protamine reversal of heparin (Group I), suggesting that a protamine-heparin interaction may be responsible. These results also suggest a rapid inactivation in vivo of clinical doses (3 mg/kg) (Group II) of infused protamine. Protamine-heparin complex formed in vitro (Group IV) also produced hemodynamic changes similar to clinical-dose protamine reversal of heparin (Group I), suggesting that formation of this complex in vivo may be the protamine-heparin interaction responsible. Protamine-heparin complex may well be a useful tool in further elucidating the full effects of protamine reversal of heparin.

Animals↗
PubMed1996

Characterization of arterial hemodynamics in rats with established hypertension.

In long-term hypertension, hemodynamic alterations are associated with functional and structural changes in the cardiovascular system. The technique of arterial impedance spectral analysis has long been used to characterize the arterial hemodynamics of steady and pulsatile components in human hypertension. Although rats with spontaneous hypertension (SHR) are the most common model for studies of primary hypertension, characterization of complete hemodynamic parameters has not been accomplished in this animal model. In the present experiment, aortic flow and pressure waves were recorded in anesthetized, open-chest and ventilated rats. Arterial impedance spectral analysis was employed to obtain steady and pulsatile hemodynamic parameters. A total of 26 SHRs (22-24 wk) and 22 age-matched normotensive WKYs was used. The purpose was to provide a comprehensive analysis of arterial hemodynamics in rats with established hypertension. The SHR had higher arterial pressure (50% increase over the control) than WKY. The total peripheral resistance was elevated by 57%. Stroke volume was decreased by 23% and heart rate increased by 18% without a significant change in cardiac output. The characteristic impedance was increased by 43%, while arterial compliance was decreased by 52%. There were also big rises in ventricular work and wave reflection. The results provide quantitative analysis of the alteration in arterial hemodynamics of steady and pulsatile components in rats with established hypertension. In long-term hypertension, the hemodynamics reflect functional abnormalities in the resistance and Windkessel vessels.

Animals↗
PubMed1998

Hemodynamic effects of middle cerebral artery stenosis and occlusion.

BACKGROUND AND PURPOSE: Middle cerebral artery (MCA) stenosis and occlusion may cause ischemic symptoms through both hemodynamic and embolic mechanisms. The purpose of this investigation was to determine the hemodynamic effects of these lesions. METHODS: Ten patients with angiographically confirmed symptomatic occlusion (n = 5) or stenosis (n = 5) of the M1 segment of the MCA were studied by clinical examination, arteriography, and positron emission tomography (PET). Arterial supply to the distal MCA territory was classified from a review of the angiogram as being through the stenosis or from pial collaterals from anterior or posterior cerebral arteries. Regional measurements of cerebral blood flow, cerebral blood volume, cerebral rate of oxygen metabolism, oxygen extraction fraction, and ratio of cerebral blood volume/cerebral blood flow (mean vascular transit time, MTT) were obtained using PET. Hemodynamic status was categorized from PET scans as stage 0, normal hemodynamics; stage 1, autoregulatory vasodilatation (increased MTT); or stage 2, increased oxygen extraction fraction. RESULTS: Of five patients with MCA occlusion, three had autoregulatory vasodilatation (stage 1) and two had increased oxygen extraction fraction distal to the lesion (stage 2). The MCA territory was supplied solely by pial collaterals in all five patients. Four of the five patients with focal MCA stenosis had normal hemodynamics (stage 0). One patient had stage 1 hemodynamic status. Blood flow to the MCA territory was through the stenosis in all patients; no pial collaterals were identified. CONCLUSION: The frequency of hemodynamic compromise in patients with MCA occlusion is high. Pial collateralization is not a specific sign of increased oxygen extraction fraction in patients with MCA occlusion.

Adolescent↗
PubMed2001

Hemodynamic changes in pseudopregnancy in chronically instrumented, conscious rats are preserved after hysterectomy.

Hemodynamic changes in early-pregnant and pseudopregnant rats are comparable, indicating that the trophoblast does not contribute to these changes. It is unclear whether the presence of the uterus is needed for the normal early-pregnancy hemodynamic adaptation. In this study we tested the hypothesis that uterine factors do not contribute to the systemic hemodynamic changes in early pseudopregnancy. To this end, we studied systemic hemodynamics in conscious pseudopregnant rats subjected to a hysterectomy, and compared these results with those obtained in a control group of pseudopregnant rats. The animals were studied on days 4, 8, 12 and 19 postmating. On day 8 of pseudopregnancy, cardiac output has increased by 23+/-7% in the hysterectomized group and 15+/-5% in the control group. In both groups this rise in cardiac output was entirely accomplished by a rise in stroke volume, by 28+/-8% and 19+/-5%, respectively. Mean arterial pressure did not change appreciably. Therefore, total peripheral resistance also decreased in both groups (17+/-6%) by day 8. After day 12 the hemodynamic parameters returned to baseline. We conclude that systemic hemodynamic changes in hysterectomized pseudopregnant rats closely resemble those in intact pseudopregnant rats. Therefore, the uterus does not seem to play a role in these changes. This supports the hypothesis that only hormones from ovarian origin trigger the initial hemodynamic adaptation to early pregnancy.

Animals↗
PubMed2006

Coronary endothelium expresses a pathologic gene pattern compared to aortic endothelium: correlation of asynchronous hemodynamics and pathology in vivo.

Coronary arteries are the most disease prone arteries in the circulation and are characterized by unique hemodynamic features, wherein wall shear stress (WSS) induced by blood flow and circumferential strain (CS) driven by pressure are highly out-of-phase temporally (asynchronous hemodynamics). To investigate whether there is a correlation between asynchronous hemodynamics and pathology in vivo, we examined endothelial cell (EC) gene expression and nuclear morphology in two distinct hemodynamic regions of male New Zealand rabbits: coronary arteries (left anterior descending artery cLAD), and aorta (aortic arch inner curvature, outer curvature, and straight descending aorta). En face imaging showed strong similarities in EC nuclear length:width ratio and angle of orientation in the cLAD and aorta. Real-time RT-PCR, however, showed that coronary arteries had significantly reduced (>5-fold) eNOS mRNA levels compared to all aortic regions, while ET-1 showed an opposite trend ( approximately 2.5-fold). Coronary arteries with characteristic asynchronous hemodynamics displayed pro-atherogenic eNOS and ET-1 gene expression profiles while the EC nuclei morphology did not differ from non-atherogenic regions in the aorta. This study demonstrates a correlation between asynchronous hemodynamics and pro-atherogenic gene expression patterns in vivo that is induced by hemodynamics inherent to the circulation.

Animals↗
PubMed2006

Pulmonary hemodynamic effects of dipyridamole infusion in patients with normal and elevated pulmonary artery systolic pressure receiving PB127.

BACKGROUND: Intravenous administration of microspheres used as ultrasound contrast agents may potentially alter pulmonary hemodynamics. PB127 (POINT Biomedical Corp., San Carlos, CA) is an investigational ultrasound perfusion-imaging agent used in conjunction with dipyridamole to diagnose coronary artery disease. The effects of PB127 alone or in combination with dipyridamole on pulmonary hemodynamics have not been described. METHODS: We studied 20 patients, including 10 with elevated screening pulmonary artery systolic pressure (>35 mm Hg). Doppler-derived pulmonary hemodynamics were determined before and after continuous infusion of PB127 (0.175 mg/kg diluted in 5% dextrose) or 5% dextrose. Patients then received dipyridamole (0.56 mg/kg) and hemodynamics were again assessed. RESULTS: During PB127/dextrose infusion, there were no significant changes in pulmonary hemodynamics compared with baseline. After dipyridamole, there were small increases in pulmonary artery systolic pressure and in pulmonary flow and a reduction in pulmonary vascular resistance. These changes occurred in patients with normal and elevated pulmonary artery systolic pressure. CONCLUSION: PB127 infusion does not alter pulmonary hemodynamics. Mild alterations of pulmonary hemodynamics occur after dipyridamole administration.

Aged↗