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PubMed2006

Adjuvant bupivacaine scalp block facilitates stabilization of hemodynamics in patients undergoing craniotomy with general anesthesia: a preliminary report.

STUDY OBJECTIVE: To evaluate the effect of 0.25% bupivacaine scalp block on alterations in hemodynamics and plasma catecholamine metabolites during general anesthesia in patients undergoing frontotemporal craniotomy. DESIGN: Prospective, clinical study. SETTING: Operating room of a university hospital. PATIENTS: 16 ASA physical status II and III patients who were scheduled for frontotemporal craniotomy. INTERVENTIONS: Patients were prospectively randomized to receive a saline control (C group) or bupivacaine scalp block (SB group) as an adjuvant to general anesthesia using isoflurane in 50% N(2)O-O(2). MEASUREMENTS: Routine monitoring of electrocardiogram, heart rate (HR), and mean arterial blood pressure (MAP) were recorded at two-minute intervals from the beginning of anesthesia until 10 minutes after incision, followed by 5-minute intervals throughout the remaining course of the surgery. By prospective design, increases in MAP or HR by 20% above the mean baseline values were treated with 2.5 mg/kg of thiopental combined with 2 mug/kg of fentanyl. Arterial blood was sampled at 5 minutes before and after skin incision and at the start of dural opening for measuring serum catecholamine metabolites by high-performance liquid chromatography. MAIN RESULTS: Only two patients in the SB group needed additional anesthetics for stabilizing their hemodynamics during the course of anesthesia. In contrast, all C group patients required supplemental anesthesia for controlling the abrupt rise in hemodynamic parameters. In addition, absolute MAP and HR values were significantly higher in the C group than in the SB group during the surgical period between incision and dural opening. The differences in hemodynamics observed between the two groups were, however, not accompanied with a significant change in plasma catecholamine metabolites at each predetermined time interval measured. CONCLUSIONS: Pretreatment with 0.25% bupivacaine scalp block appeared to be an effective adjuvant treatment for maintaining stable hemodynamics for patients undergoing craniotomy during general anesthesia especially at the time of skin incision and dural opening. This study design was unable to discern any correlation between elevation in hemodynamic parameters and a rise in serum catecholamine levels.

Adjuvants, Pharmaceutic↗
PubMed2006

Correlation and comparison of body mass index on hemodynamics in hypertensive and normotensive patients undergoing intravenous sedation.

PURPOSE: The purpose of this project was to retrospectively compare and correlate body mass index (BMI) and hemodynamics in hypertensive and normotensive patients undergoing intravenous sedation for dentoalveolar surgery. PATIENTS AND METHODS: A retrospective chart analysis of 263 consecutive male patients undergoing intravenous (IV) sedation for dentoalveolar surgery was divided into 5 BMI groups: underweight, normal weight, overweight, obese, extremely obese. Data recorded were noninvasive baseline and intraoperative hemodynamic measurements at 5-minute intervals for systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), pulse pressure (PP), and pulse (P). Statistical analysis of mean values between groups was carried out using multivariate linear regression analysis, Pearson's correlation coefficient, and Student's t test and found significant for P < .05. RESULTS: Average hemodynamic values for normotensive patients were significantly lower for all groups except for pulse in the normal group, pulse in the obese group, and DBP in the extremely obese group. For normotensive patients, there were statistically significant strong positive correlation for elevated BMI and increased baseline changes in SBP and PP. For the hypertensive group, there was a statistically significant moderate positive correlation for elevated BMI and increased baseline changes in PP and statistically significant strong positive correlation for baseline changes in MAP. Baseline changes were significant for greater increases in SBP and decreases in DBP and MAP in the underweight hypertensive group. Significant increases from baseline in the normotensive group were for PP in the normal BMI group and for pulse in the obese group. All baseline changes, with the exception of normotensive underweight SBP (+26.7%) and hypertensive PP (+23.9%), were within +/-20% of baseline (range, -12.2% to +17.4%). CONCLUSION: In general, normotensive patients in this study had lower average hemodynamic values than hypertensive patients in all BMI groups. Great variability was seen in baseline changes for all BMI groups, but a substantial majority of changes were within +/-20% of baseline. There were statistically significant moderate and positive correlations in BMI for changes from baseline for several hemodynamic measurements. Intravenous sedation for oral and maxillofacial surgery procedures maintains a stable hemodynamic state in hypertensive and normotensive patients regardless of BMI.

Adult↗
PubMed2006

Practical issues of hemodynamic monitoring at the bedside.

The hemodynamic monitoring of a surgical patient acquires a major relevance in high-risk patients and those suffering from surgical diseases associated with hemodynamic instability, such as hemorrhagic or septic shock. This article reviews the fundamental physiologic principles needed to understand hemodynamic monitoring at the bedside. Monitoring defines stability, instability, and response to therapy. The major hemodynamic parameters measured and derived from invasive hemodynamic monitoring, such as arterial, central venous, and pulmonary catheterization, are discussed, as are its clinical indications, benefits, and complications. The current clinical data relevant to hemodynamic monitoring are reviewed and discussed.

Blood Pressure↗
PubMed2006

Effects of Russell's viper venom fractions on systemic and renal hemodynamics.

Changes in systemic and renal hemodynamics induced by Russell's viper venom are well established. The component of the venom responsible for hemodynamic alteration has not been identified. By Sephadex column chromatography five fractions of Russell's viper (Daboia russellii siamensis) venom were isolated. Each venom fraction consisted of phospholipase A2, proteolytic enzyme, phosphomonoesterase, phosphodiesterase, arginine ester hydrolase and hyaluronidase of varying activities. Hemodynamic effects of each venom fraction including mean arterial pressure, cardiac output, systemic and renal vascular resistance, renal blood flow and glomerular filtration rate were studied in five groups of dogs; each group had four dogs. Minimal hemodynamic changes were observed in dogs receiving venom fraction I. Increased renal vascular resistance with diminution of renal blood flow and glomerular filtration rate was observed in dogs receiving venom fractions II, III, IV and V. A markedly increased renal vascular resistance with maximal decrease in renal blood flow and glomerular filtration rate was caused by fraction III of the venom with highest PLA2 and proteolytic enzyme activities. However, renal hemodynamic changes appeared to correlate better with proteolytic enzyme activity than PLA2 activity. The findings suggested the proteolytic enzyme as an important determinant of hemodynamic alteration. Fractional excretion of Na was increased in dogs injected with venom fraction IV, and is presumed to be due to the inhibition of tubular reabsorption of Na by a natriuretic factor in this venom fraction.

Animals↗
PubMed2003

A prospective evaluation of hemodynamic instability during off-pump coronary artery bypass surgery.

OBJECTIVE: Despite recognized hemodynamic derangements during cardiac displacement, most patients appear to tolerate the off-pump procedure well. However, some patients unpredictably become hemodynamically unstable requiring emergency cardiopulmonary bypass or intra-aortic balloon pump support. After an experience of 5306 multivessel off-pump coronary artery bypasses (OPCABs), this study was undertaken to determine the factors that would identify the patients who were at a higher risk for the procedure. DESIGN: Prospective clinical investigation. SETTING: Tertiary care academic cardiac care center. PARTICIPANTS: Five hundred consecutive patients undergoing multivessel OPCAB from September to December 2001. INTERVENTIONS: Various cardiac and extracardiac factors were charted in prespecified data-entry forms. Multiple logistic regression analysis was done to determine if any identifiable factors were predictors of a higher risk of unacceptable hemodynamic instability during OPCAB. Institution of IABP support or conversion to CPB were the endpoints of the study. MEASUREMENTS AND MAIN RESULTS: Of the 500 patients studied, significant hemodynamic instability developed in 24 (4.8%) patients. IABP support was instituted in 16 (3.2%) patients, and 8 (1.6%) were converted to CPB. Stepwise logistic regression identified ejection fraction <25% (p < 0.001), myocardial infarction of <1-month duration (p = 0.009), congestive heart failure (p = 0.016), and preoperative hemodynamic instability (p = 0.057) as predictors of conversion during OPCAB. CONCLUSIONS: Patients with low left ventricular ejection fraction <25%, myocardial infarction of <1-month duration, congestive heart failure, or preoperative hemodynamic instability constitute the high-risk group for OPCAB.

Aged↗
PubMed1996

The effect of midazolam at two plasma concentrations of hemodynamics and sufentanil requirement in coronary artery surgery.

OBJECTIVES: In this study, the hemodynamics and sufentanil requirement were compared at two midazolam target plasma concentrations in patients undergoing coronary artery bypass grafting (CABG). DESIGN: Prospective, randomized study. SETTING: University hospital, single institution. PARTICIPANTS: Patients undergoing CABG. INTERVENTIONS: Patients were randomly assigned to receive midazolam at a target plasma concentration of 150 ng/mL (group 1; n = 10) or 300 ng/mL (group 2; n = 10). Sufentanil infusion was titrated to maintain hemodynamic stability, defined as mean arterial pressure within 15% of baseline values. All patients received preoperative beta-blocking agents. Arterial blood samples of midazolam and sufentanil were analyzed by high-performance liquid chromatography and radioimmunoassay, respectively. MEASUREMENTS AND MAIN RESULTS: The mean dose of sufentanil (7.5 +/- 1.7 microgram/kg in group 1 v 7.2 +/- 2.5 micrograms/kg in group 2) did not differ. There were no significant differences in hemodynamics between the groups in the period before or after cardiopulmonary bypass (CPB). Before CPB, in two patients in each group, hypertension was controlled with sufentanil only. One patient in group 1 required a vasodilator in addition to sufentanil. No ischemic events occurred before CPB. After CPB, one patient in group 2 required a vasodilator to control hypertension. Two patients in group 2 required treatment with nitroglycerin for myocardial ischemia. Stable plasma concentrations of sufentanil and midazolam were obtained during and after CPB. The midazolam infusion was continued in both groups at a rate of 1.25 micrograms/kg/min during the first 4 postoperative hours. The time to awakening did not differ between the groups (100 +/- 58 minutes in group 1 v 173 +/- 147 minutes in group 2) nor did the plasma concentrations of midazolam (96 +/- 28 ng/mL v 108 +/- 42 ng/mL) at the time of awakening. Intraoperative awareness was not reported. CONCLUSION: In patients undergoing CABG, good hemodynamic control with a similar incidence of hemodynamic interventions was observed at midazolam target plasma concentrations of 150 and 300 ng/mL when coadministered with sufentanil. The sufentanil requirement was identical in both groups. This study suggests that a midazolam plasma concentration of 150 ng/mL is sufficient to provide satisfactory hemodynamic control and to avoid intraoperative awareness.

Adjuvants, Anesthesia↗
PubMed2002

"A La Carte" treatment of portal hypertension: Adapting medical therapy to hemodynamic response for the prevention of bleeding.

We report the results of adapting medical therapy to the monitoring of hemodynamic response in the prevention of a first variceal bleeding or rebleeding in patients with cirrhosis. Hepatic venous pressure gradient (HVPG) was measured before and after propranolol was initiated. The patients were considered responders if HVPG decreased below 12 mm Hg or at least 20% as compared with baseline value. If patients were not responders, isosorbide-5 mononitrate (I-5MN) was added, and a third hemodynamic study was performed. Thereafter, the patients were followed for a mean of 28 months. Thirty-four consecutive patients were treated to prevent a first bleeding episode in 20 patients and a rebleeding in 14 patients. HVPG value was initially 19.8 +/- 4.6 mm Hg and decreased to 17.6 +/- 5.7 mm Hg (P <.05) after propranolol alone. Thirteen patients (38%) were responders to propranolol. I-5MN improved hemodynamic response in 7 cases. Among these 20 (59%) hemodynamic responders, only 2 (10%) experienced variceal bleeding, as compared with 9 of 14 (64%) nonresponders (P <.05). Using multivariate analysis, only hemodynamic response was found to have an independent predictive value for the risk of variceal bleeding. In conclusion, hemodynamic response to drug therapy identifies patients who are efficiently protected from variceal bleeding as well as nonresponders in whom an alternative treatment should be considered.

Adult↗
PubMed1999

The role of angiotensin II AT1 receptor in the maintenance of hemodynamics in a canine model of coronary microembolization-induced heart failure.

The purpose of this study was to determine whether Angiotensin II (Ang II) contributes to the regulation of resting hemodynamics via Ang II type 1 (AT1) receptors in awake dogs with coronary microembolization-induced heart failure. Six dogs were surgically instrumented for measurement of systemic hemodynamics and for coronary microembolization. The acute hemodynamic effects of a selective AT1-receptor antagonist, GR138950 (1 mg/kg, i.v.), were determined before and after congestive heart failure (CHF). GR138950 had no effects on hemodynamics before CHF Daily coronary microembolizations (through the previously implanted coronary catheter) resulted in CHF, as documented by hemodynamic measurements, a slight but significant increased Ang II plasma level (17.4 +/- 1.6 vs. 23 +/- 1.0 pg/ml; p < 0.05), and characteristic clinical signs of CHF. After CHF, GR138950 significantly increased left ventricular dP/dt(max) (LVdP/dt(max)) from 1,754 +/- 68 to 2,347 +/- 114 mm Hg/s and decreased LV systolic pressure (LVSP) from 118 +/- 5 to 101 +/- 7 mm Hg; meanwhile, heart rate (from 132 +/- 4 to 102 +/- 6 beats/min) and LV end-diastolic pressure (LVEDP; from 17 +/- 3 to 9 +/- 1.5 mm Hg) were significantly decreased. Mean arterial pressure (MAP) was not affected. The peak effects occurred 90 min after administration. Thus Ang II contributes significantly to resting hemodynamics via AT1 receptors in this CHF model; that is, the specific AT1 blocker inhibits the negative inotropic actions of Ang II in the CHF state.

Angiotensin II↗
PubMed2004

Injury (nociceptive afferent nerve stimulation) modifies the hemodynamic and metabolic responses to hemorrhage in immature swine.

OBJECTIVE: To determine the effects of reinfusion of shed blood on the regional blood flow changes induced by hemorrhage and hemorrhage plus nociceptive nerve stimulation (injury) with special reference to the gut. DESIGN: Randomized controlled laboratory study. SETTING: Medical Research Council laboratory, university medical school. SUBJECTS: Four groups of anesthetized immature female Large-White pigs (15-27 kg): 30% hemorrhage, 30% hemorrhage plus afferent nerve stimulation, nerve stimulation alone, surgical controls. INTERVENTIONS: In addition to standard invasive hemodynamic monitoring, electromagnetic flow probes were placed around a branch of the superior mesenteric artery and the right femoral artery. Stimulating electrodes were placed on brachial nerves in both axillae. Animals underwent 30% hemorrhage over 30 mins. After a 30-min shock period, the shed blood was reinfused at 2 mL/kg/min. MEASUREMENTS AND MAIN RESULTS: Measurements/calculations of standard global hemodynamics, gut and femoral blood flows/vascular resistance, metabolism, arterial plasma lactate, portal venous endotoxin, interleukin-6, and tumor necrosis factor-alpha were made before and after hemorrhage, before and after reinfusion, and at 30-min intervals for 3 hrs. Blood and tissue samples were taken for the presence of translocated coliforms. Hemorrhage elicited the expected changes in global hemodynamics, metabolism, and gut and femoral blood flows. There was a partial hemodynamic recovery during the shock period. Nearly all hemodynamic and metabolic variables were rapidly restored by reinfusion. The response to hemorrhage was modified by nerve stimulation: Reductions in systemic hemodynamics and gut flow were greater, and there was no recovery during the shock phase. Cytokine and endotoxin concentrations increased significantly in all groups. There was no bacterial translocation. CONCLUSIONS: When hemorrhage occurs in the presence of nerve stimulation (injury), the relative protection of the gut circulation is attenuated and this effect persists after the end of hemorrhage and reinfusion. However, there was no evidence that injury increased the hemorrhage/surgery-induced cytokine and endotoxin responses.

Analysis of Variance↗
PubMed2003

Effects of hemodynamic instability on brain death-induced prepreservation liver damage.

BACKGROUND: Brain death (BD) is an important multifactorial variable contributing to donor-specific liver damage. Our study aimed at assessing the specific effects of hemodynamic instability on systemic and hepatic parameters of perfusion, bowel ischemia, and oxidative stress in a porcine model of BD. METHODS: BD was induced in 16 pigs (German Landrace, 18-28 kg) in two groups (hypotension-BD [HYPO-BD], n=8; normotension-BD [NORM-BD], n=8), which were compared with control animals/living donors (n=6) for a period of 2 hr. We analyzed systemic hemodynamic parameters, bowel ischemia (intramucosal pH in the stomach and colon, plasma endotoxin levels, and endotoxin-neutralizing capacity [ENC]), and oxidative stress (total glutathione levels in erythrocytes) and compared the findings with hepatic parameters of perfusion (hepatic arterial flow, portal venous flow, and microperfusion) and liver oxidative stress (reduced glutathione and oxidized glutathione levels in the liver). RESULTS: Independent of the hemodynamic stability, liver macrocirculation and microcirculation decreased (HYPO-BD, 79+/-6 to 69+/-10 mL/100 g/min; NORM-BD, 81+/-10 to 73+/-7 mL/100 g/min; P<0.05). Hepatocellular damage (aspartate aminotransferase: NORM-BD, 49+/-20 units/L; HYPO-BD, 170+/-140 units/L; P<0.01) and hepatic oxidative stress (reduced glutathione in the liver/oxidized glutathione in the liver: NORM-BD, 29.4+/-2.3 to 13.0+/-1.3; HYPO-BD, 29.4+/-2.3 to 9.05+/-0.81; P<0.001) increased in both BD groups. With dependence on systemic hemodynamic parameters, bowel ischemia increased (intramucosal pH in the colon, 7.22+/-0.01, P<0.01; ENC, 75+/-14 endotoxin-neutralizing units/mL, P<0.01; endotoxin levels, 7+/-2 to 43+/-10 pg/mL, P<0.01) in the HYPO-BD group but not in the NORM-BD group or the living donor group. Furthermore, systemic oxidative stress was increased in the HYPO-BD group only (total glutathione levels in erythrocytes, 2.65+/-0.25 to 0.15+/-0.25 mM; P<0.01). CONCLUSIONS: During BD, liver-specific parameters (portal venous flow, microperfusion, aspartate aminotransferase activity, ENC, and hepatic oxidative stress) were compromised, independent of the hemodynamic status. Therefore, the systemic hemodynamic status does not reflect the functional status of the liver during BD.

Animals↗
PubMed1997

Hemodynamic deterioration following radiofrequency ablation of the atrioventricular conduction system.

Radiofrequency ablation of the atrioventricular conduction system (ACS) has become an established therapy for patients with drug refractory atrial fibrillation. We observed eight patients with hemodynamic deterioration after radiofrequency ablation of the atrioventricular conduction system. As we found hemodynamic deterioration related to worsening mitral regurgitation, we compared the clinical history, electrophysiological, and echocardiographic data from the patients with hemodynamic deterioration and worsening mitral regurgitation (group 1) to those without hemodynamic deterioration and stable mitral regurgitation after the procedure (group 2). Eight out of 108 patients (7.4%) undergoing ablation of the ACS deteriorated hemodynamically with acute pulmonary edema in three and congestive heart failure in five patients occurring at a mean of 3 and 8 weeks, respectively, after the procedure. Three of these patients were referred for mitral valve surgery. Two patients underwent ablation using a left-sided approach. A right-sided approach was used in five patients. In one patient, a left- and right-sided approach was used. Compared to group 2 patients, group 1 patients had significantly higher left ventricular end-diastolic diameters (64 +/- 6 mm vs 56 +/- 9 mm) at baseline despite similar fractional shortening (32% +/- 11% vs 34% +/- 13%), left ventricular end-systolic diameters (43 +/- 9 mm vs 36 +/- 7 mm) and degree of mitral regurgitation (1.4 +/- 1.1 vs 1.4 +/- 0.7) on echocardiographic analysis. Thus, hemodynamic deterioration together with progression of mitral regurgitation is a potential complication of ablation of the ACS (up to 7.4%). Patients with high left ventricular end-diastolic diameters and moderate mitral regurgitation at baseline seem prone to this complication.

Adult↗
PubMed2006

Statistical hemodynamics: a tool for evaluating the effect of fluid dynamic forces on vascular biology in vivo.

BACKGROUND: In vivo experimentation is the most realistic approach for exploring the vascular biological response to the hemodynamic stresses that are present in life. Post-mortem vascular casting has been used to define the in vivo geometry for hemodynamic simulation; however, this procedure damages or destroys the tissue and cells on which biological assays are to be performed. METHOD OF APPROACH: Two statistical approaches, regional (RSH) and linear (LSH) statistical hemodynamics, are proposed and illustrated, in which flow simulations from one series of experiments are used to define a best estimate of the hemodynamic environment in a second series. As an illustration of the technique, RSH is used to compare the gene expression profiles of regions of the proximal external iliac arteries of swine exposed to different levels of time-average shear stress. RESULTS: The results indicate that higher shears promote a more atheroprotective expression phenotype in porcine arterial endothelium. CONCLUSION: Statistical hemodynamics provides a realistic estimate of the hemodynamic stress on vascular tissue that can be correlated against biological response.

Animals↗
PubMed2001

Severe hemodynamic impairment and border zone--region infarction.

PURPOSE: To investigate the relationship between the patterns of cerebral infarction that have been associated with hemodynamic impairment and the presence of severe chronic hemodynamic compromise (increased oxygen extraction fraction) in a large prospectively enrolled group of patients with carotid artery occlusion. MATERIALS AND METHODS: At enrollment in a prospective study of cerebral hemodynamics, 110 patients with carotid occlusion underwent (a) positron emission tomography for the measurement of cerebral oxygen extraction fraction and (b) computed tomographic (CT) or magnetic resonance (MR) examinations of the brain. Infarcts were categorized retrospectively by vascular territory, location, and pattern. The association of these findings with hemodynamic impairment (increased oxygen extraction fraction) was investigated. RESULTS: No border zone-region infarctions were found in 35 asymptomatic patients. In 75 symptomatic patients, cortical border zone-region infarction was found in seven of 36 patients with increased oxygen extraction fraction, and in two of 39 with normal oxygen extraction fraction (P =.08, difference not significant). The pattern of multiple white matter lesions arranged parallel to the lateral ventricle was observed only in symptomatic patients with increased oxygen extraction fraction (eight of 36 patients; P =.002; sensitivity, 22%; specificity, 100%). This finding was more frequent with MR imaging (seven of 14 patients) than with CT (one of 22 patients). CONCLUSION: Multiple white matter infarctions, arranged parallel to the lateral ventricle, are associated with severe hemodynamic impairment. This pattern of infarction is likely due to a hemodynamic mechanism.

Adult↗
PubMed2006

Hemodynamics in the mouse aortic arch as assessed by MRI, ultrasound, and numerical modeling.

Mice are widely used to study arterial disease in humans, and the pathogenesis of arterial diseases is known to be strongly influenced by hemodynamic factors. It is, therefore, of interest to characterize the hemodynamic environment in the mouse arterial tree. Previous measurements have suggested that many relevant hemodynamic variables are similar between the mouse and the human. Here we use a combination of Doppler ultrasound and MRI measurements, coupled with numerical modeling techniques, to characterize the hemodynamic environment in the mouse aortic arch at high spatial resolution. We find that the hemodynamically induced stresses on arterial endothelial cells are much larger in magnitude and more spatially uniform in the mouse than in the human, an effect that can be explained by fluid mechanical scaling principles. This surprising finding seems to be at variance with currently accepted models of the role of hemodynamics in atherogenesis and the known distribution of atheromatous lesions in mice.

Animals↗
PubMed2005

Hemodynamic reserve and high-intensity transient signals in moyamoya disease.

BACKGROUND: Moyamoya disease (MMD) as a rare obstructive cerebrovascular disease is assumed to present with ischemic symptoms due to hemodynamic compromise. However, alternative mechanisms, such as cerebral embolism in low-flow territories, may also contribute to clinical symptoms. The incidence of high-intensity transient signals (HITS) and the degree of hemodynamic compromise were studied in symptomatic patients with MMD. METHODS: Twenty-four patients (17 female, 7 male; mean age 33 +/- 13 years) with clinical symptoms attributable to cerebral ischemia and the angiographic features of MMD (21 definite form, 3 probable MMD; 22 patients 'late stage' MMD, 2 patients 'early stage' MMD) in 45 affected hemispheres were enrolled in the present study. Patients underwent parallel estimation of hemodynamic compromise by means of functional blood flow (rCBF) studies using SPECT, PET or xenon-CT and HITS detection by TCD. RESULTS: Hemodynamic compromise was observed in 37/40 (92%) hemispheres studied. During TCD monitoring, HITS were detected in 3 patients (12.5%), with a total frequency of 3 (6.6%) in the 45 hemispheres investigated. All patients with HITS showed hemodynamic compromise in functional rCBF studies. In these patients, HITS were recorded ipsilateral to the symptomatic hemisphere. HITS occurred in late stage MMD patients only once, while both cases with early stage MMD demonstrated multiple HITS. CONCLUSIONS: The incidence of HITS in patients with MMD appears to be lower compared to patients with atherosclerotic or atherothrombotic arterial obstructions. In addition, ischemia-related symptoms in 'late stage' MMD seem to be caused by hemodynamic compromise in the majority of these patients.

Adult↗
PubMedDate not supplied

[The importance of hemodynamic monitoring in mitral and tricuspid valve surgery].

INTRODUCTION: Untreated mitral valve disease is associated with marked hemodynamic disorders, low ejection fraction (EF) and poor perfusion. The study aimed to explore the importance of hemodynamic monitoring in intraoperative evaluation and treatment of these patients. MATERIAL AND METHODS: This prospective study included 85 patients: group 1: 41 patients, EF<40%; group 11: 44 patients, EF>40%. Hemodynamic parameters were recorded after initation of anesthesia (1), after sternotomy (2), after extracorporeal circulation (ECC) (3) and before leaving the operation theatre (4). The following parameters were assessed: mean arterial pressure, mean pulmonary artery pressure, pulmonary capillary wedge pressure, pulmonary vascular resistance index, central venous pressure, cardiac index. Statistical analysis was performed using Student t-test and correlation analyses in time series. RESULTS AND DISCUSSION: Hemodynamic parameters were changed at the beginnig of surgery, but gradually improved after sternotomy and were normal at the end of the operation. Both examined groups presented with reduction of the pulmonary artery preassure, pulmonary capillary wedge pressure, pulmonary vascular resistance index (reduction more than 30%) and cardiac index (up to 100%). Strong correlation between 1/2 and 3/4 assessments pointed to the importance of intraoperative evaluation. Swan-Ganz catheter ia a valuable tool used for hemodynamic monitoring. CONCLUSION: Intraoperative medication (based on obtained hemodynamic parameters) and operative treatment led to normalization of all parameters in both groups, regardless of the preoperative values of EF.

Cardiovascular Physiological Phenomena↗
PubMedDate not supplied

Hemodynamics in sepsis.

Hemodynamics in sepsis change as sepsis develops. Initial hemodynamics of sepsis often are much different from later stages of sepsis, shifting from low cardiac output states to high cardiac output states. Tissue oxygenation also changes with initial mixed venous oxyhemoglobin (Svo2) or central venous oxyhemoglobin (Scvo2) levels below normal, with later stages reflecting high values. These changes occur as sepsis progresses, producing a marked disturbance in capillary flow and tissue oxygenation. Treatments for these changes in sepsis are different, making the identification of the hemodynamic state essential to optimally treat the patient. Fortunately, hemodynamic monitoring techniques are markedly improved from older techniques such as the pulmonary artery catheter. With noninvasive techniques such as esophageal and external Doppler for measuring hemodynamics, clinicians beyond the intensive care unit can make hemodynamic assessments that were not possible until just recently. This improved assessment should make it much easier to properly identify sepsis and initiate appropriate treatments in a timely manner.

Blood Flow Velocity↗
PubMed2005

Correlation between lumenal geometry changes and hemodynamics in fusiform intracranial aneurysms.

BACKGROUND AND PURPOSE: Hemodynamics may predispose aneurysms to rupture; however, hemodynamic descriptors that can describe aneurysm growth are not well understood. We examined the relationship between hemodynamics and growth of 2 fusiform basilar artery aneurysms in an effort to define hemodynamic variables that may be helpful in predicting aneurysmal growth. METHODS: Two patients with basilar fusiform aneurysms of a similar size were followed for a 2-year period. The lumenal geometry and inflow and outflow rates were acquired by using MR angiography and velocimetry, respectively. The location of aneurysmal growth was identified by coregistering aneurysm models that were acquired at different times. Hemodynamic descriptors were calculated by using computational fluid dynamic simulations and compared with aneurysm growth pattern. RESULTS: One patient had an aneurysm that grew significantly, but a similar-sized aneurysm in the other patient remained unchanged. The largest aneurysmal growth (approximately 3 mm/year) was found at the inferior side (lower part) of the aneurysm, where the wall shear stress was very low (<0.1N/m(2)). The general flow patterns did not change with time, even in the aneurysm that grew, but histograms of wall shear stress were very different in these 2 patients. CONCLUSIONS: This study investigates whether hemodynamic descriptors can be correlated with regional changes in aneurysm lumen morphology on a patient-specific basis. That capability will permit the testing, in longitudinal studies, of hypotheses as to which mechanisms are the most important in aneurysm growth.

Aged↗