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PubMed2005

A temporal comparison of BOLD, ASL, and NIRS hemodynamic responses to motor stimuli in adult humans.

In this study, we have preformed simultaneous near-infrared spectroscopy (NIRS) along with BOLD (blood oxygen level dependent) and ASL (arterial spin labeling)-based fMRI during an event-related motor activity in human subjects in order to compare the temporal dynamics of the hemodynamic responses recorded in each method. These measurements have allowed us to examine the validity of the biophysical models underlying each modality and, as a result, gain greater insight into the hemodynamic responses to neuronal activation. Although prior studies have examined the relationships between these two methodologies through similar experiments, they have produced conflicting results in the literature for a variety of reasons. Here, by employing a short-duration, event-related motor task, we have been able to emphasize the subtle temporal differences between the hemodynamic parameters with a high contrast-to-noise ratio. As a result of this improved experimental design, we are able to report that the fMRI measured BOLD response is more correlated with the NIRS measure of deoxy-hemoglobin (R = 0.98; P < 10(-20)) than with oxy-hemoglobin (R = 0.71), or total hemoglobin (R = 0.53). This result was predicted from the theoretical grounds of the BOLD response and is in agreement with several previous works [Toronov, V.A.W., Choi, J.H., Wolf, M., Michalos, A., Gratton, E., Hueber, D., 2001. "Investigation of human brain hemodynamics by simultaneous near-infrared spectroscopy and functional magnetic resonance imaging." Med. Phys. 28 (4) 521-527.; MacIntosh, B.J., Klassen, L.M., Menon, R.S., 2003. "Transient hemodynamics during a breath hold challenge in a two part functional imaging study with simultaneous near-infrared spectroscopy in adult humans". NeuroImage 20 1246-1252.; Toronov, V.A.W., Walker, S., Gupta, R., Choi, J.H., Gratton, E., Hueber, D., Webb, A., 2003. "The roles of changes in deoxyhemoglobin concentration and regional cerebral blood volume in the fMRI BOLD signal" Neuroimage 19 (4) 1521-1531]. These data have also allowed us to examine more detailed measurement models of the fMRI signal and comment on the roles of the oxygen saturation and blood volume contributions to the BOLD response. In addition, we found high correlation between the NIRS measured total hemoglobin and ASL measured cerebral blood flow (R = 0.91; P < 10(-10)) and oxy-hemoglobin with flow (R = 0.83; P < 10(-05)) as predicted by the biophysical models. Finally, we note a significant amount of cross-modality, correlated, inter-subject variability in amplitude change and time-to-peak of the hemodynamic response. The observed co-variance in these parameters between subjects is in agreement with hemodynamic models and provides further support that fMRI and NIRS have similar vascular sensitivity.

Adult↗
PubMed1997

Right and left ventricular hemodynamic performance during sustained ventricular tachycardia.

Several factors may influence hemodynamic tolerance of a ventricular tachycardia (VT) episode but, to date, only VT rate has been used as a major detection criterion in selecting implantable cardioverter-defibrillator therapy algorithms. We examined hemodynamic changes during VT in humans and a possible correlation between left and right ventricular hemodynamic indexes. Right ventricular hemodynamic indexes could reflect systemic hemodynamics but previous studies have been inconclusive. Patients with coronary artery disease and a history of recurrent, sustained VT were studied. Aortic pressure and right and left ventricular pressures were simultaneously recorded with 2 dual micromanometer-tipped high-fidelity pressure catheters during sinus rhythm and during induced sustained monomorphic VT. Beat-to-beat analysis was performed using custom-made software. Nine patients (7 men, mean age 60 +/- 8 years, mean ejection fraction 24 +/- 8%) with 11 VT episodes (mean cycle length 283 +/- 48 ms) were studied. During VT, left and right ventricular systolic pressures showed a mean decrease of 57% and 26%, respectively, with weak correlation (r = 0.67, p = 0.06) between both values. There was also an increase in mean left and right ventricular end-diastolic pressures of 26% and 74%, respectively, and no correlation was seen (r = -0.2, p = 0.6). A significant correlation was found between changes in left and right ventricular maximal positive dP/dt (55% and 28% decrease, respectively (r = 0.69, p = 0.03) and between changes in left and right ventricular maximal negative dP/dt (64% vs 39% decrease, r = 0.71, p = 0.02). Most ventricular time parameters in both ventricles differed significantly during VT compared with sinus rhythm; however, only the decrease in right ventricular time to end-diastolic pressure correlated with the decrease in left ventricular systolic pressure, at the 10th VT beat (r = 0.8, p = 0.01). We conclude that left and right ventricles are hemodynamically unequally affected during rapid VT. Although right ventricular pressures cannot be reliably used to assess changes in the hemodynamic status of the left ventricle, additional parameters, such as dP/dt or changes in ventricular time intervals, should be further evaluated for inclusion in implantable cardioverter-defibrillator algorithms.

Aged↗
PubMed1998

Hemodynamic and hormonal changes during pneumoperitoneum and trendelenburg positioning for operative gynecologic laparoscopy surgery.

Objective: The number and types of surgical procedures being preformed using laparoscopic technique is increasing due to technological advances. Recent studies suggest the carbon dioxide pneumoperitoneum and patient positioning causes hemodynamic alterations, respiratory acidosis, and a release of stress hormones. However, to date, no studies have investigated the physiological effect of laparoscopic procedures lasting more than 60 minutes on the stress response and the effect of Trendelenburg positioning. The purpose of this study was to identify the physiological effect of pneumoperitoneum and positioning during prolonged laparoscopy on hemodynamic (cardiac index, mean arterial pressure, heart rate, systemic vascular resistance, and stroke volume), metabolic (arterial blood gases), and hormone (arginine vasopressin, aldosterone, and plasma renin activity) parameters. We hypothesized that pneumoperitoneum and patient positioning will alter the hemodynamic, hormone, and metabolic parameters.Methods: The study was longitudinal in design and sampled a total of 31 healthy subjects having a gynecologic oncologic laparoscopic procedure at Hurley Medical Center, Flint, Michigan. The subjects were randomly assigned one of three groups receiving an initial insufflation pressure of either 10, 15, or 18 mmHg. After obtaining informed consent hemodynamic, metabolic, and hormone measurements were obtained at the following times: 1) pre-induction, 2) post-induction, 3) post-insufflation, 4) post-Trendelenburg 5 minutes and at 30, 60, 90, and 120 minutes post-insufflation. The results were analyzed using multivariate analysis of variance for repeated measures with a P <.05. A power of 0.9 was obtained to identify changes over time.Results: During the time course of the study the hemodynamic, metabolic, and hormonal parameters showed significant alterations. The most dramatic hemodynamic changes occurred post-insufflation characterized by a decrease in cardiac index and stroke volume with a concurrent increase in systemic vascular resistance. The metabolic parameters showed a significant decrease in pH and corresponding increase in PaCO(2). However, the pH and PaCO(2) remained within normal limits through the study. As part of the study's protocol the investigators increased minute volume to control for a rise in PaCO(2) during the procedure. A significant increase was noted in aldosterone and arginine vasopressin at post-insufflation and Trendelenburg positioning. Plasma renin activity showed a dramatic increase following post-insufflation. None of the subjects developed any post anesthetic complications.Conclusion: Our study demonstrated that pneumoperitoneum and Trendelenburg positioning cause statistically significant elevations in the stress hormones and concurrently cause a decrease in hemodynamic parameters. A healthy patient may tolerate these changes but a patient with cardiovascular disease or pulmonary problems may not be able to compensate as efficiently.

Journal Article↗
PubMed2003

Glomerular endothelial dysfunction and hemodynamic maladjustment in vesicoureteric reflux.

A structural defect of the non-vascular component of a nephron namely vesicoureteric reflex (VUR) can induce injury to the vascular component, which is reflected by the alteration in intrarenal hemodynamics. A mild alteration in intrarenal hemodynamics was observed in grades I-II VUR which revealed (a) mild reductions in renal plasma flow (RPF) 543 +/- 104 mL/min/1.73 m2; in peritubular capillary flow (PTCF) 438 +/- 103mL/min/1.73 m2; in glomerular filtration rate (GFR) 105 +/- 19 mL/min/1.73 m2 and in ultrafiltration coefficient (KFG) 0.04 +/- 0.01 mL/s/mmHg; (b) normal values of filtration fraction (FF) 0.2 +/- 0.04, of intraglomerular hydrostatic pressure (PG) 50 +/- 0.3 mmHg, and of afferent arteriolar resistance (RA) 2261 +/- 718 dyne s cm(-5); and (c) a slight elevation of efferent arteriolar resistance (RE) 3914 +/- 962 dyne s cm(-5). In contrast, a moderately severe alteration in intrarenal hemodynamics was observed in severe VUR (grades III up) which revealed greater reductions in RPF 267 +/- 114 mL/min/1.73 m2, in PTCF 195 +/- 90 mL/min/1.73 m2, in GFR 72 +/- 34 mL/min/1.73 m2 and in KFG 0.03 +/- 0.01 mL/s/mmHg; and elevation of PG 53 +/- 2 mmHg, of filtration fraction 0.27 +/- 0.07, of RA 4557 +/- 2340 dyne s cm(-5) and of RE 9417 +/- 4163 dyne s cm(-5). Such an alteration in intrarenal hemodynamics observed in severe VUR induces both intraglomerular hypertension (elevated PG) and an exaggeratedly reduced PTCF. This intrarenal hemodynamic defect is due to the glomerular endothelial dysfunction and its hemodynamic maladjustment. In accordance with the preceding information, treatment to correct the hemodynamic maladjustment is likely to improve renal function and prevent renal disease progression.

Capillaries↗
PubMed1981

Recognition and surgical management of patent but hemodynamically failed arterial grafts.

During a five-year period, 34 patients had persistence or recurrence of abnormal hemodynamic measurements in limbs after arterial reconstruction depsite graft patency documented by arteriography. Initial operations included aortofemoral (four), femorofemoral (ten), femoropopliteal (18), and femorotibial (two) bypass. Immediate postoperative hemodynamic failure was documented in seven patients by a mean ankle/brachial systolic pressure index increase of only 0.05 +/- 0.04 following the initial reconstruction. The remaining 27 patients had delayed hemodynamic failure; mean increase in ankle pressure was only 0.06 +/- 0.05 from the preoperative period until time of detection of failure (average duration 2.5 years). In all 34 patients, arteriography demonstrated patency of the initial graft. In conjunction with the vascular laboratory examination, arteriography identified the cause of hemodynamic failure to be inadequate inflow in 10 patients, poor outflow in 16, combined inflow and outflow obstruction in one, and graft stenosis in seven. Unrecognized stenosis in areas proximal (two patients) and distal (three patients) to the bypass emphasized the importance of complete biplanar arteriography before initial operation. Reoperation was successful in correcting hemodynamic failure in 26 patients (76.5%) with a mean increase in ankle index of 0.41 +/- 0.15. Operation was technically not feasible in four patients and was not performed in another four patients because of concomitant medical problems. In two of these patients, progression to graft thrombosis was documented. The results of this study suggest that early objective recognition of an anatomically patent but hemodynamically failed graft is possible by frequent noninvasive testing. Prompt investigation by arteriography defines the cause and location of failure, and reoperation restores normal limb hemodynamics. Most important, reoperation permits salvage of the majority of these patent grafts prior to ultimate failure from thrombosis.

Adult↗
PubMed1996

Temporal correlation mapping analysis of the hemodynamic penumbra in mutant mice deficient in endothelial nitric oxide synthase gene expression.

BACKGROUND AND PURPOSE: Mice containing deletions in the genes encoding nitric oxide (NO) synthase have been useful to dissect the role of NO in cerebral ischemia. We recently reported that mice lacking expression of the endothelial isoform of NO synthase (eNOS) develop larger infarcts after middle cerebral artery occlusion. Because NO or a related product of NO synthase activity is important for relaxation of cerebral blood vessels, we examined for possible hemodynamic differences in the peri-ischemic zone of eNOS-deficient and wild-type mice after middle cerebral artery occlusion using functional CT scanning techniques. METHODS: Wild-type SV129 mice (n = 10) and mice deficient in eNOS gene expression (n = 10) were subjected to middle cerebral artery occlusion under halothane anesthesia. Thirty minutes after ischemia, functional CT scanning was performed with dynamic scanning protocols to measure the cerebral transit profiles of injected contrast agents. A temporal correlation mapping technique was used to analyze the pattern of hemodynamic perturbations based on alterations in the shape of the cerebral transit profiles. Statistical thresholds defined the hemodynamic core and penumbra. RESULTS: Hemodynamic deficits were more severe in the mutant than wild-type mouse. When expressed as a percentage of the total insult, core areas were significantly increased in mutant mice (39.8 +/- 3.7%) compared with wild types (28.8 +/- 3.4%). Conversely, areas of the hemodynamic penumbra were significantly smaller in mice deficient in eNOS activity (60.2 +/- 3.7%) than in wild-type mice (71.2 +/- 3.4%). Furthermore, the calculated relative perfusion index within the hemodynamic penumbra was significantly lower in the group with eNOS gene deletion (35.6 +/- 1.5% in mutants versus 43.0 +/- 2.4% in wild types). CONCLUSIONS: These data indicate that mice lacking eNOS expression show a greater degree of hemodynamic compromise after middle cerebral artery occlusion and suggest that a product of eNOS activity (eg. NO) may protect brain after focal cerebral ischemia, possibly by improving blood flow within the penumbral zone.

Animals↗
PubMedDate not supplied

Conception of the venous hemodynamics in the lower extremity.

Contradictory reports on the significance of several hemodynamic phenomena, such as femoral vein incompetence and incompetent calf perforators, impede orientation in venous hemodynamics. Venous pressure difference arising between the popliteal and the posterior tibial vein during the activity of the calf muscle venous pump was reported for the first time about 50 years ago, but regrettably, this important discovery continues to be unrespected. The venous pressure difference has since been termed ambulatory pressure gradient and seems to be the key factor triggering the venous reflux in the lower limb as well as the process leading to varicose vein recurrence. On the other hand, simultaneous recordings of the mean venous pressure in the posterior tibial and long saphenous veins demonstrated that the pressure curves have been identical at rest, during ambulation, and in the recovery period, a finding typical of conjoined vessels. Bidirectional flow within calf perforators taking place both in healthy subjects and in patients with varicose veins enables a quick equilibration of pressure changes between deep and superficial veins of the lower leg. Reflux disturbing the venous hemodynamics is in various degrees dependent on the quantity of retrograde flow; abolition of reflux restores normal venous hemodynamics. Reflux in superficial veins, if large enough, may cause the most severe form of chronic venous insufficiency. Femoral vein incompetence and incompetent calf perforators per se do not produce ambulatory venous hypertension and do not cause hemodynamic disturbance. This study discusses the controversial issues, tries to define and appraise the principal hemodynamic phenomena (ambulatory venous hypertension, ambulatory pressure gradient, venous reflux, superficial and deep vein incompetence, incompetent perforators), mentions a possible relation between deep vein incompetence and varicose veins, and attempts to present, based on proved facts, a comprehensive picture of the venous hemodynamics in the lower extremity.

Humans↗
PubMed2001

[Renal and uterine hemodynamics in pregnant women with hypertension].

AIM: To study gestational alterations of renal and uterine hemodynamics, their relationships with systemic and intracardiac hemodynamics in pregnant women (PW) with essential hypertension (EH). MATERIAL AND METHODS: Echocardiography, ultrasound dopplerography of renal and uterine arteries, roll-over test were made in the course of trimester II-III and 3 months after the delivery in 48 PW with EH degree 1-2 and control 20 healthy PW. Hemodynamic parameters in pregnancy were compared to postpartum ones. The latter were supposed to be basal. RESULTS: Changes in systemic and intracardiac hemodynamics in EH and control women were in many respects similar but systolic blood pressure in EH changed insignificantly, minute volume increased owing to increased heart rate. PW with EH of the second degree have in the III trimester more frequent positive roll-over test this evidencing for high pressor reactivity of the vascular system. PW with EH showed higher speed of the blood flow in the renal arteries in unchanged resistance. With growing gestation time the resistance of the uterine arteries declined. The resistance of the main stem of the renal artery went up in enhanced cardiac contraction regardless of total peripheral vascular resistance (TPVR). Blood flow in the uterine arteries worsened in elevation of arterial pressure, TPVR, lowering of the heart rate and systolic function of the heart. Renal and uterine hemodynamics were independent. CONCLUSION: Hemodynamic changes in control and EH PW were similar in many respects but higher arterial pressure, abnormal systolic function of the left ventricle, bradycardia disturb uterine blood flow. Renal circulation was independent of systemic and intracardiac hemodynamics and is unrelated to changes in the uterine circulation.

Adult↗
PubMed2003

Echocardiographic predictors of hemodynamic response and significance of dyspnea development in patients with mitral stenosis during dobutamine stress echocardiography.

BACKGROUND AND AIM OF THE STUDY: In mitral stenosis (MS) patients, resting hemodynamic data do not always correlate with symptom severity. Stress tests may be carried out in these patients, but the mechanisms of different hemodynamic and clinical responses to stress are not clearly established. The study aim was to evaluate hemodynamic changes that correlate with dyspnea development during dobutamine infusion (DI) in patients with MS, and to assess determinants of transmitral gradient response. METHODS: Forty-five consecutive mild or moderately symptomatic patients (36 women, nine men; mean age 44 +/- 10 years; range: 26-66 years), in NYHA class II and with MS (mean mitral valve area (MVA) 1.6 +/- 0.1 cm2; range: 1.5-1.9 cm2) were evaluated with dobutamine stress echocardiography. RESULTS: During DI, dyspnea developed in 12 patients, and 33 patients remained asymptomatic. During infusion, both mean transmitral gradient (6 +/- 3 versus 11 +/- 6 mmHg, p = 0.01) and pulmonary artery systolic pressure (PASP) (13 +/- 4 versus 21 +/- 3 mmHg, p < 0.001) were significantly increased in patients who developed dyspnea compared to others. Hence, a subgroup of patients with more serious MS was identified using the hemodynamic response to dobutamine. Based on these clinical and hemodynamic results, management was changed in 12 patients (27%); five underwent percutaneous mitral balloon commissurotomy and seven received intensive medical treatment. In all patients, PASP at rest (p = 0.001), MVA (p < 0.0001) and subvalvular mitral score (p = 0.004), which is indicative of mitral valve damage, were significantly correlated with mean mitral valve gradient response. CONCLUSION: These results suggest that patients in whom dyspnea is provoked during DI show a greater increase in hemodynamic parameters than patients in whom provocation does not occur. The mean mitral valve gradient-response correlates with baseline pulmonary artery pressure, MVA and subvalvular echo score, and may be predicted by these parameters. Association between dyspnea and presence of severe mitral valve hemodynamics showed a high sensitivity and negative and positive predictive value. It is possible that dyspnea may be of value in identifying those patients with significant mitral valve obstruction.

Adrenergic beta-Agonists↗
PubMed2005

Risk factors for hemodynamically-unrelated cystic periventricular leukomalacia in very low birth weight premature infants.

BACKGROUND AND PURPOSE: Periventricular leukomalacia (PVL) is one of the most important complications of prematurity, but its cause remains unclear. This study investigated the risk factors for hemodynamically-unrelated cystic PVL in very low birth weight (VLBW) premature infants. METHODS: VLBW premature infants admitted to the neonatal intensive care unit from 1998 through 2002 were included in this retrospective study. Infants who had congenital lethal anomalies or who died before a cranial scan could be done were excluded. All VLBW infants received serial cranial ultrasound examinations to screen for cystic PVL during hospitalization. Infants with cystic PVL were divided into those with or without a hemodynamic event of sufficient severity to potentially cause cystic PVL. The charts of all included infants were reviewed and relevant clinical parameters were analyzed. RESULTS: Cystic PVL occurred in 20 VLBW infants (6.9%) during the study period. Four of these infants (20%) had hemodynamic events before the development of cystic PVL and 16 (80%) had hemodynamically-unrelated cystic PVL. Univariate analysis showed that infants with hemodynamically-unrelated cystic PVL were more likely to have symptomatic patent ductus arteriosus (PDA) [p < 0.01] and bronchopulmonary dysplasia (BPD) [p < 0.01]. However, logistic regression indicated VLBW premature infants with BPD combined with symptomatic PDA (odds ratio, 8.92; 95% confidence interval, 2.55-31.20; p < 0.01) were at greatest risk for development of hemodynamically-unrelated cystic PVL. CONCLUSION: BPD and symptomatic PDA were more common in infants with hemodynamically-unrelated cystic PVL, although the reasons for these associations were unclear. Serial cranial scans are strongly suggested for VLBW premature infants with BPD and symptomatic PDA to screen for the development of cystic PVL.

Bronchopulmonary Dysplasia↗
PubMed2005

[Association of clinical features with different hemodynamic patterns in head-up tilt test in children with unexplained syncope].

OBJECTIVE: To explore the different hemodynamic patterns during the course of head-up tilt tests in children with unexplained syncope and the association of clinical features with different hemodynamic patterns in head-up tilt test in children with unexplained syncope. METHODS: 100 pediatric patients with unexplained syncope, aged 11 +/- 2 (6-16), 36 male and 64 female, with the mean course of 10 +/- 16 months (2 d-5 y), underwent head-up tilt tests or head-up tilt tests potentiated with nitroglycerine under quiet circumstance. Blood pressure and heart rate were monitored simultaneously. According to their different hemodynamic patterns, they were divided into vasovagal response pattern, postural orthostatic tachycardia syndrome (POTS) response pattern, orthostatic hypotension (OH) response pattern and normal response pattern. The vasovagal response was divided into vasodepressor, cardioinhibitory and mixed patterns. The distribution and different clinical features of different response patterns in the unexplained syncope were also studied. RESULTS: Fifty (50%) of the 100 children with unexplained syncope displayed the hemodynamic pattern of vasovagal response, among which 31 (31%) displayed the pattern of vasodepressor response, 7 (7%) cardioinhibitory response, and 12 (12%) mixed response. Thirty-three patients (33%) displayed POTS response, 2 (2%) OH response, and 15 (15%) the normal hemodynamic response. Patterns of dysautonomic response and chronotropic incompetence were not observed in these children with unexplained syncope. The age of the children with normal response during HUT was 10 +/- 3 years, significantly younger than that of the children with vasovagal response and POTS response (12 +/- 2 and 12 +/- 2, both P < 0.01). There were no differences in sex ratio and duration of syncope among the vasovagal response, POTS and normal response. But the syncopal spells in the children with POTS response was less frequent and the baseline heart rate of the children with POTS response was 81 +/- 7, significantly faster than that of the children with vasovagal response and normal response (71 +/- 9 and 74 +/- 7, both P < 0.01). There was no significant difference in the baseline blood pressure among the children with vasovagal response, POTS and normal response. There were also no significant differences in the age, sex ratio, and duration of syncope, number of syncopal spells, baseline heart rate, and baseline blood pressure among the children with vasodepressor response, cardioinhibitory response and mixed response. CONCLUSION: There are different hemodynamic response patterns in head-up tilt testing in children with unexplained syncope, and there was some association between hemodynamic response patterns and their clinical features.

Adolescent↗
PubMed2006

A multi-center study of hemodynamic characteristics exhibited by children with unexplained syncope.

BACKGROUND: Syncope is common in children and adolescents, with 15% estimated to have had at least one syncopal episode by age 18. In recent years, an increasing number of children, especially girls at their school age, have developed unexplained syncope. The mechanism of an unexplained syncope exhibited by children is incompletely studied; the association between different hemodynamic patterns and clinical features is also not clear. The aim of the study was to investigate the hemodynamic patterns of children with unexplained syncope and to examine the clinical relevance. METHODS: Two hundred and eight children [87 boys, 121 girls, aged 3 - 19 years, mean (11.66 +/- 2.72) years] were selectively recruited from May 2000 to April 2006 when they presented syncope as their main complaint at the Multi-center Network for Childhood Syncope in Beijing, Hunan Province, Hubei Province, and Shanghai of China. All of the patients underwent head-up tilt tests; data were analyzed using SPSS version 10.0 for Windows. Continuous variables were expressed as the mean +/- standard deviation. Dichotomous variables were compared through a chi(2) test. A value of P < 0.05 (two sided) was regarded as statistically significant. RESULTS: The age distribution of children with syncope was approximately normal. Head-up tilt tests was positive in 155 children, and the incidence of positive response of the baseline head-up tilt test for diagnosing unexplained syncope was 50.48%. The sensitivity value and diagnostic value of sublingual nitroglycerin head-up tilt test were both 74.52%. The hemodynamic pattern was normal in 53 children. The 155 children, who were positive in head-up tilt tests, showed signs of postural orthostatic tachycardia syndrome (60, 28.8%), the vasoinhibitory pattern (72, 34.6%), the cardioinhibitory pattern (5, 2.4%), and the mixed pattern (18, 8.7%). The gender distribution between the two age groups (age < 12 years vs age > or = 12 years) was not different (P > 0.05). The distribution of hemodynamic patterns between the children of the two age groups (age < 12 years vs age > or = 12 years), and the children with different complaints (dizziness vs syncope) was significantly different (P < 0.05), while the distribution between the children of different sexes and different lasting time of syncope (< or = 5 minutes vs > 5 minutes) was not significantly different (P > 0.05). Different hemodynamic patterns were differentiated by differing syncope inducements, presymptoms, and complicated symptoms during and after syncope. CONCLUSION: The tested girls were more prone when compared with the boys to have unexplained syncope, and the peak age was around twelve years old. The incidence of positive response of head-up tilt tests was also relatively higher for the girls. The distribution of hemodynamic patterns for different ages was different. For children with unexplained syncope, we should use head-up tilttests to distinguish the hemodynamic patterns in order to adopt rational therapeutic measures.

Adolescent↗
PubMedDate not supplied

Aortofemoral reconstruction for multilevel disease: a prospective hemodynamic study.

A prospective study was undertaken to evaluate the clinical and hemodynamic effects of aortofemoral Dacron reconstruction in patients with multilevel disease (i.e. aortoiliac and femoropopliteal occlusive disease). Thirty nine patients underwent, apart from clinical evaluation, segmental plethysmography and Doppler pressures before operation, immediately after operation and again at 3 and 6 months. All patients improved by the reconstruction, but 12 (31%) continued to complain of disabling claudication during normal daily activities. The mean ankle pressure and thigh pressure index improved by 37.5%. This was accompanied by a decrease of peak flow time, an increase of peak flow and an improved recovery during reactive hyperemia. Furthermore an additional significant rise of the ankle pressure index was noted between 3 and 6 months. Continuing claudication was always associated with both initial and late hemodynamic failure (the criterium for hemodynamic success was defined as an increase of the ankle pressure index with more than 0.1). Hemodynamic success resulted unvariably in clinical success. However 4 patients were clinically symptomfree, although they had to be classified as hemodynamic failures. It is concluded that a significant number of patients fail to obtain complete relief after proximal reconstruction. Preoperative hemodynamic studies may provide additional information, but hemodynamic and clinical results do not always correlate with each other.

Aged↗
PubMed2003

Isolated limb perfusion: distinct tourniquet and tumor necrosis factor effects on the early hemodynamic response.

HYPOTHESIS: Recent evidence indicates that tumor response rates after isolated limb perfusion (ILP) are improved when tumor necrosis factor (TNF) is added to the locoregional perfusion of high doses of chemotherapy. Other factors, related to the patient or the ILP procedure, may interfere with the specific role of TNF in the early hemodynamic response after ILP with TNF and high-dose chemotherapy. DESIGN: Case-control study. SETTING: Tertiary care university hospital. PATIENTS: Thirty-eight patients with a locoregionally advanced tumor of a limb treated by ILP with TNF and high-dose chemotherapy (TNF group) were compared with 31 similar patients treated by ILP with high-dose chemotherapy alone (non-TNF group). INTERVENTIONS: Swan-Ganz catheter hemodynamic recordings, patients' treatment data collection, and TNF and interleukin 6 plasma level measurements at regular intervals during the first 36 hours following ILP. MAIN OUTCOME MEASURES: Hemodynamic profile and total fluid and catecholamine administration. RESULTS: In the TNF group, significant changes were observed (P<.006): the mean arterial pressure and the systemic vascular resistance index decreased, and the temperature, heart rate, and cardiac index increased. These hemodynamic alterations started when the ILP tourniquet was released (ie, when or shortly after the systemic TNF levels were the highest). The minimal mean arterial pressure, the minimal systemic vascular resistance index, the maximal cardiac index, the intensive care unit stay, and the interleukin 6 maximal systemic levels were significantly (P<.001 for all) correlated to the log(10) of the systemic TNF level. In the non-TNF group, only a brief decrease in the blood pressure following tourniquet release and an increase in the temperature and in the heart rate were statistically significant (P<.006). Despite significantly more fluid and catecholamine administration in the TNF group, the mean arterial pressure and the systemic vascular resistance index were significantly (P<.001) lower than in the non-TNF group. CONCLUSIONS: Release of the tourniquet induces a blood pressure decrease that lasts less than 1 hour in the absence of TNF and that is distinct from the septic shock-like hemodynamic profile following TNF administration. The systemic TNF levels are correlated to this hemodynamic response, which can be observed even at low TNF levels.

Adult↗
PubMed2005

Hemodynamic changes during laparoscopic gastric bypass procedures.

HYPOTHESIS: Significant detrimental intra-operative hemodynamic and respiratory changes occur in the morbidly obese during laparoscopic gastric bypass. DESIGN: Case series. SETTING: Tertiary care university hospital. PATIENTS: Thirteen patients, 10 women and 3 men, undergoing uncomplicated laparoscopic gastric bypass for morbid obesity. INTERVENTIONS: Using a pulmonary artery catheter and an arterial line, we intraoperatively monitored hemodynamic and respiratory parameters. Parameter values were recorded at set points of the procedure, and the changes were statistically analyzed. RESULTS: Significant hemodynamic and respiratory changes, mostly unfavorable, occur in the morbidly obese when creating the pneumoperitoneum in preparation for laparoscopic gastric bypass. The hemodynamic changes are attenuated when the patient is placed in the reverse Trendelenburg position and almost completely corrected when the abdomen is deflated at the completion of the procedure. The respiratory changes are more persistent. CONCLUSIONS: Laparoscopic gastric bypass surgery for morbid obesity leads to a number of predominantly detrimental, if temporary, respiratory and hemodynamic changes, which are most pronounced at the time of creation of the pneumoperitoneum. In the presence of significant cardiopulmonary comorbidities, the use of invasive intra-operative hemodynamic monitoring of the morbidly obese undergoing laparoscopic gastric bypass appears therefore justified.

Adult↗
PubMedDate not supplied

Importance of hemodynamic factors in the prognosis of symptomatic carotid occlusion.

CONTEXT: The relative importance of hemodynamic factors in the pathogenesis and treatment of stroke in patients with carotid artery occlusion remains controversial. OBJECTIVE: To test the hypothesis that stage II cerebral hemodynamic failure (increased oxygen extraction measured by positron emission tomography [PET]) distal to symptomatic carotid artery occlusion is an independent risk factor for subsequent stroke in medically treated patients. DESIGN AND SETTING: Prospective, blinded, longitudinal cohort study of patients referred from a group of regional hospitals between 1992 and 1996. PATIENTS: From 419 subjects referred, 81 with previous stroke or transient ischemic attack in the territory of an occluded carotid artery were enrolled. All were followed up to completion of the study, with average follow-up of 31.5 months. MAIN OUTCOME MEASURES: Telephone contact every 6 months recorded the subsequent occurrence of all stroke, ipsilateral ischemic stroke, and death. RESULTS: Stroke occurred in 12 of 39 patients with stage II hemodynamic failure and in 3 of 42 patients without (P = .005); stroke was ipsilateral in 11 of 39 patients with stage II hemodynamic failure and in 2 of 42 patients without (P = .004). Six deaths occurred in each group (P = .94). The age-adjusted relative risk conferred by stage II hemodynamic failure was 6.0 (95% confidence interval [CI], 1.7-21.6) for all stroke and 7.3 (95% CI, 1.6-33.4) for ipsilateral stroke. CONCLUSIONS: Stage II hemodynamic failure defines a subgroup of patients with symptomatic carotid occlusion who are at high risk for subsequent stroke when treated medically. A randomized trial evaluating surgical revascularization in this high-risk subgroup is warranted.

Aged↗
PubMed1988

Hemodynamic effects of contrast media during coronary angiography: a comparison of three nonionic agents to Hypaque-76.

Coronary angiography with standard ionic contrast media is associated with marked alterations in cardiac hemodynamics because of the depressant effects of the contrast media on cardiac contractility. Nonionic contrast media have been reported to produce less hemodynamic alteration than standard ionic contrast media. However, there is no information on how one nonionic media compares to another. Thus we compared the hemodynamic effects of three nonionic contrast media, Iopamidol (IOP), Iohexol (IOH), and Ioversol (IOV) to each other as well as to the standard ionic contrast media Hypaque-76 (H76). In 20 closed-chest anesthetized dogs, we recorded the maximal change in left ventricular systolic pressure (LVSP), mean aortic pressure, left ventricular diastolic pressure (LVDP), and left ventricular dp/dt during 10-cc left main coronary artery injections of H76, IOP, IOH, and IOV. The mean aortic pressure and LVSP decreased 36 +/- 17 mm Hg and 46 +/- 21 mm Hg with H76 but only 5 +/- 5 mm Hg and 6 +/- 5 mm Hg with IOP, 5 +/- 4 mm Hg and 6 +/- 6 mm Hg with IOH, and 5 +/- 4 mm Hg and 7 +/- 6 mm Hg with IOV (P less than 0.001). The LVDP increased 6 +/- 5.0 mm Hg with H76 but only 0.2 +/- 0.5 mm Hg with IOP, 0.2 +/- 0.3 mm Hg with IOH, and 0.5 +/- 1.0 mm Hg with IOV (P less than 0.001). The LV dp/dt decreased 545 +/- 261 mm Hg/sec with H76 but increased 886 +/- 477 mm Hg/sec with IOP, 910 +/- 96 mm Hg/sec with IOH, and 473 +/- 335 mm Hg/sec with IOV (P less than 0.001). Whereas each nonionic agent produced significantly less hemodynamic abnormalities than H76, there was no significant difference between any of the nonionic agents on any hemodynamic parameter. Thus, as compared to H76, these nonionic contrast media produced only trivial alterations in hemodynamics and LV dp/dt. These agents may be preferable in patients with LV dysfunction.

Angiography↗
PubMed2004

Hemodynamic significance of heart rate in neurally mediated syncope.

BACKGROUND: Vasovagal and vasodepressor syncope are used interchangeably in the literature to describe the common faint syndrome, now collectively named neurally mediated syncope. The significance of heart rate (HR) in these reflex-induced reactions remains unclear. HYPOTHESIS: The study was undertaken to investigate the hemodynamic significance of HR in tilt-induced neurally mediated syncope. METHODS: In all, 113 patients with syncope of unknown etiology were studied by head-up tilt test with invasive hemodynamic monitoring. Thirty-five patients (15 women, 20 men, age range 21 to 72 years) developed syncope and were enrolled for analysis. The hemodynamic data were compared between patients who developed bradycardia (vasovagal group, n = 15) and those without bradycardia (vasodepressor group, n = 20). RESULTS: The baseline hemodynamic data (mean +/- standard deviation) and the hemodynamic responses after 10-min headup tilt were similar between patients in the vasovagal and vasodepressor groups. During syncope, patients with vasovagal reaction developed hypotension and paradoxical bradycardia (HR = 52.4 +/- 5.9 beats/min), while patients with vasodepressor reaction developed a precipitous drop in arterial blood pressure with inappropriate HR (105 +/- 21 beats/min) compensation. Patients with vasovagal syncope manifested a significantly lower cardiac index and a significantly higher systemic vascular resistance index than patients with vasodepressor syncope (1.47 +/- 0.29 vs. 1.97 +/- 0.41 1/min/m2, p < 0.001 and 2098 +/- 615 vs. 1573 +/- 353 dynes x s x cm(-5) x m2, p < 0.003, respectively). A positive correlation existed between HR and cardiac index (r = 0.44, p = 0.008) during syncope in the patients studied. CONCLUSIONS: These findings suggest that the hemodynamic characteristics of vasovagal and vasodepressor reactions are different, and that HR plays a significant role in neurally mediated syncope.

Adult↗