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PubMed1997

Hemodynamic effects of transdermal estradiol alone and combined with norethisterone acetate.

A 24 weeks, randomized, two-period, placebo controlled study was conducted to compare the effects of continuous transdermal 17 beta-estradiol replacement therapy (0.05 mg/day once a week) with placebo on systemic hemodynamics and blood pressure in postmenopausal women. Twenty-nine postmenopausal women (47-62 years) free of hormone replacement therapy were randomized in two groups; group 1 received estradiol patches for the first 12 weeks and placebo patches for the second, and group 2 received the same treatments in the reverse order. The effect of combined estradiol plus oral norethisterone acetate (NETA) 1 mg was also evaluated in the subset of women with intact uteri (n = 24). Crossover analysis showed that stroke volume and cardiac output were significantly higher (P < 0.05) and blood pressure was significantly lower (P < 0.05) with estradiol, irrespective of the order in which the treatments were administered. Although correlations between plasma estradiol levels during active treatment and hemodynamic changes were not significant, hemodynamic changes were significantly greater above 63 pg/ml than below this level (P < 0.05). Oral norethisterone acetate administration either during transdermal placebo or estradiol arms tended to modify systemic hemodynamics in the same direction than estradiol but the changes did not attained statistical significance. In summary compared with placebo, transdermal 17 beta-estradiol, replacement to postmenopausal women, increased cardiac output and decreased blood pressure. Although the average magnitude of changes was small, the results suggest that plasma estradiol levels could be a source of individual variability in the hemodynamic response. Oral NETA administration tended to enhance rather than reverse the estradiol-induced changes.

Administration, Cutaneous↗
PubMed2003

Ongoing right ventricular hemodynamics in heart failure: clinical value of measurements derived from an implantable monitoring system.

OBJECTIVES: This study examined the characteristics of continuously measured right ventricular (RV) hemodynamic information derived from an implantable hemodynamic monitor (IHM) in heart failure patients. BACKGROUND: Hemodynamic monitoring might improve the day-to-day management of patients with chronic heart failure (CHF). Little is known about the characteristics of long-term hemodynamic information in patients with CHF or how such information relates to meaningful clinical events. METHODS: Thirty-two patients with CHF received a permanent RV IHM system similar to a single-lead pacemaker. Right ventricular systolic and diastolic pressures, heart rate, and pressure derivatives were continuously measured for nine months without using the data for clinical decision-making or management of patients. Data were then made available to clinical providers, and the patients were followed up for 17 months. Pressure characteristics during optimal volume, clinically determined volume-overload exacerbations, and volume depletion events were examined. The effect of IHM on hospitalizations was examined using the patients' historical controls. RESULTS: Long-term RV pressure measurements had either marked variability or minimal time-related changes. During 36 volume-overload events, RV systolic pressures increased by 25 +/- 4% (p < 0.05) and heart rate increased by 11 +/- 2% (p < 0.05). Pressure increases occurred in 9 of 12 events 4 +/- 2 days before the exacerbations requiring hospitalization. Hospitalizations before using IHM data for clinical management averaged 1.08 per patient year and decreased to 0.47 per patient-year (57% reduction, p < 0.01) after hemodynamic data were used. CONCLUSIONS: Long-term ambulatory pressure measurements from an IHM may be helpful in guiding day-to-day clinical management, with a potentially favorable impact on CHF hospitalizations.

Adult↗
PubMed1984

Right ventricular infarction: identification by hemodynamic measurements before and after volume loading and correlation with noninvasive techniques.

To evaluate the potential occurrence of right ventricular infarction, 53 patients with acute inferior transmural myocardial infarction were studied within 36 hours of symptoms by right heart catheterization, equilibrium radionuclide angiography and two-dimensional echocardiography. Technetium-99m pyrophosphate myocardial scintigraphy was performed 3 days after the onset of symptoms. The hemodynamic standard for right ventricular infarction was defined as both a right atrial pressure of 10 mm Hg or more and a right atrial/pulmonary artery wedge pressure ratio of 0.8 or more. Eight (15%) of the 53 patients had hemodynamic measurements at rest characteristic of right ventricular infarction, and 6 (11%) additional patients met these criteria after volume loading (p less than 0.05). Nineteen (37%) of the 51 patients who had radionuclide angiography had right ventricular dysfunction manifested by both a reduced right ventricular ejection fraction (less than 40%) and right ventricular regional wall motion abnormalities (akinesia or dyskinesia). An abnormal radionuclide angiogram was observed in 12 of 13 patients with hemodynamic measurements indicating right ventricular infarction. In 12 patients with an abnormal radionuclide angiographic study, right ventricular ejection fraction improved 6 to 12 weeks after infarction (27 +/- 7 to 36 +/- 9%, p less than 0.01). Twenty-two (49%) of the 45 patients with adequate two-dimensional echocardiograms had a right ventricular regional wall motion abnormality. An abnormal two-dimensional echocardiogram was seen in 9 of 11 patients with hemodynamic measurements characteristic of right ventricular infarction. Technetium-99m pyrophosphate scintigraphy was positive for right ventricular infarction in 3 of 12 patients who had hemodynamic measurements indicating right ventricular infarction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Prognostic importance of the immediate hemodynamic response to nifedipine in patients with severe left ventricular dysfunction.

To determine the clinical significance of the occurrence of hemodynamic deterioration after the administration of calcium channel blocking drugs, nifedipine (20 mg orally) was administered to 29 patients with severe left ventricular dysfunction. Thirteen patients showed hemodynamic improvement with the drug (Group 1), as shown by a notable increase in cardiac index associated with a modest decrease in mean arterial pressure. The other 16 patients exhibited hemodynamic deterioration after nifedipine (Group 2), as reflected by a decline in right and left ventricular stroke work indexes accompanied by a marked hypotensive response. These differences were not related to differences in the peripheral vascular response to nifedipine, because both groups showed similar decreases in systemic and pulmonary vascular resistances. Groups 1 (hemodynamic improvement) and 2 (hemodynamic deterioration) were similar with respect to all demographic variables and pretreatment left ventricular performance (cardiac index, left ventricular filling pressure and systemic vascular resistance). Yet, the 1 year actuarial survival in patients in Group 1 was substantially better than that in patients in Group 2 (67 versus 23%, p = 0.009). Group 2, however, had higher values for plasma renin activity (17.7 +/- 6.0 versus 4.3 +/- 1.4 mg/ml per h, p less than 0.05), lower values for serum sodium concentration (134.6 +/- 1.2 versus 139.2 +/- 0.6 mEq/liter, p less than 0.05) and higher values for mean right atrial pressure (15.8 +/- 2.0 versus 7.9 +/- 1.4 mm Hg, p less than 0.01) than did patients in Group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1998

Correlation between hemodynamic changes and tomographic sestamibi imaging during dipyridamole-induced coronary hyperemia.

OBJECTIVES: The purposes of this study were to examine the effects of dipyridamole infusion on hemodynamic variables and to compare these changes with myocardial perfusion. BACKGROUND: Dipyridamole stress testing with myocardial perfusion imaging is widely used in the assessment of patients with known or suspected coronary artery disease (CAD). Few studies, however, have correlated the hemodynamic effects of dipyridamole using invasive monitoring with perfusion patterns in patients with chest pain syndromes. METHODS: Hemodynamic measurements were made in the cardiac catheterization laboratory with a Swan-Ganz thermodilution catheter before, during and after infusion of dipyridamole (142 microg/kg body weight per min for 4 min). Technetium-99m sestamibi was injected 3 min after the completion of the infusion. RESULTS: There were 20 patients with and 6 without CAD, as demonstrated by angiography. Compared with baseline values, dipyridamole resulted in an increase in pulmonary capillary wedge pressure (54 +/- 78% vs. 32 +/- 26%, p = NS), cardiac index (36 +/- 21% vs. 40 +/- 18%, p = NS) and stroke volume index (16 +/- 18% vs. 40 +/- 18%, p = NS) and a decrease in systemic vascular resistance (22 +/- 13% vs. 24 +/- 11%, p = NS), aortic pressure (2 +/- 9% vs. 0 +/- 6%, p = NS) and pulmonary vascular resistance (19 +/- 25% vs. 11 +/- 32%, p = NS) in patients with and without CAD. The peak effect of dipyridamole on heart rate, systemic vascular resistance and pulmonary capillary wedge pressure was evident at 3 min after infusion in 70% of patients. Aminophylline, given to 20 patients, improved hemodynamic variables within 2 min. The single-photon emission computed tomographic sestamibi images were normal in the 6 patients without and abnormal in the 18 patients with CAD. CONCLUSIONS: Dipyridamole-induced coronary hyperemia produces mild hemodynamic changes in patients with and without CAD; these changes are at or near peak effect at 3 min after infusion and are rapidly reversed by aminophylline.

Adult↗
PubMed1997

Effect of high intensity exercise training on central hemodynamic responses to exercise in men with reduced left ventricular function.

OBJECTIVES: The aim of this study was to evaluate the effects of high intensity exercise training on left ventricular function and hemodynamic responses to exercise in patients with reduced ventricular function. BACKGROUND: Results of studies on central hemodynamic adaptations to exercise training in patients with chronic heart failure have been contradictory, and some research has suggested that training causes further myocardial damage in these patients after a myocardial infarction. METHODS: Twenty-five men with left ventricular dysfunction after a myocardial infarction or coronary artery bypass graft surgery were randomized to an exercise training group (mean age +/- SD 56 +/- 5 years, mean ejection fraction [EF] 32 +/- 7%, n = 12) or a control group (mean age 55 +/- 7 years, mean EF 33 +/- 6%, n = 13). Patients in the exercise group performed 2 h of walking daily and four weekly sessions of high intensity monitored stationary cycling (40 min at 70% to 80% peak capacity) at a residential rehabilitation center for a period of 2 months. Ventilatory gas exchange and upright hemodynamic measurements (rest and peak exercise cardiac output; pulmonary artery, wedge and mean arterial pressures; and systemic vascular resistance) were performed before and after the study period. RESULTS: Maximal oxygen uptake (VO2max) increased by 23% after 1 month of training, and by an additional 6% after month 2. The increase in VO2max in the trained group paralleled an increase in maximal cardiac output (12.0 +/- 1.8 liters/min before training vs. 13.7 +/- 2.5 liters/min after training, p < 0.05), but maximal cardiac output did not change in the control group. Neither stroke volume nor hemodynamic pressures at rest or during exercise differed within or between groups. Rest left ventricular mass, volumes and EF determined by magnetic resonance imaging were unchanged in both groups. CONCLUSIONS: High intensity exercise training in patients with reduced left ventricular function results in substantial increases in VO2max by way of an increase in maximal cardiac output combined with a widening of maximal arteriovenous oxygen difference, but not changes in contractility. Training did not worsen hemodynamic status or cause further myocardial damage.

Cardiac Output↗
PubMed1998

Comparative efficacy of a two-hour regimen of streptokinase versus alteplase in acute massive pulmonary embolism: immediate clinical and hemodynamic outcome and one-year follow-up.

OBJECTIVES: This study sought to compare the efficacy of 2-h regimens of alteplase and streptokinase in acute massive pulmonary embolism. The primary end point was immediate hemodynamic improvement, and secondary end points included early clinical efficacy and safety, as well as 1-year clinical outcome. BACKGROUND: Several thrombolytic regimens have been compared for the past 10 years in randomized studies, showing that 2-h infusion regimens of alteplase or urokinase lead to faster hemodynamic improvement than former 12- to 24-h administration protocols in acute massive pulmonary embolism. Many trials have focused on immediate hemodynamic and angiographic outcomes, but none has addressed long-term follow-up after thrombolysis. METHODS: Sixty-six patients with acute massive pulmonary embolism (Miller score > 17 and mean pulmonary artery pressure >20 mm Hg) were randomly assigned to receive either a 100-mg 2-h infusion of alteplase (n = 23) or 1.5 million IU of streptokinase over 2 h (n = 43). In both groups, heparin infusion was started at the end of thrombolytic infusion and adapted thereafter. Total pulmonary resistance was monitored over a 12-h period. Pulmonary vascular obstruction was assessed 36 to 48 h after thrombolytic therapy. One-year follow-up information included death, cause of death, recurrent pulmonary embolism, chronic thromboembolic pulmonary hypertension, stroke and bleeding. RESULTS: Both groups had similar baseline angiographic and hemodynamic characteristics of severity, with maintained cardiac output in 64 (97%) of 66 patients. The results (mean +/- SD) demonstrated that despite a faster total pulmonary resistance improvement observed at 1 h in the alteplase group compared with the streptokinase group (33+/-16% vs. 19 16%, p = 0.006), a similar hemodynamic efficacy was obtained at 2 h when both thrombolytic regimens were completed (38+/-18% vs. 31+/-19%). There was no significant difference in either pulmonary vascular obstruction at 36 to 48 h or bleeding complication rates. One-year event-free survival was similar in both groups, as most events were related to concomitant diseases. CONCLUSIONS: These results suggest that a 2-h regimen of streptokinase can be routinely used in patients with massive pulmonary embolism and maintained cardiac output without obviously compromising efficacy or safety.

Acute Disease↗
PubMed1999

Hemodynamic and physical performance during maximal exercise in patients with an aortic bioprosthetic valve: comparison of stentless versus stented bioprostheses.

OBJECTIVES: The objective of this study was to compare stentless bioprostheses with stented bioprostheses with regard to their hemodynamic behavior during exercise. BACKGROUND: Stentless aortic bioprostheses have better hemodynamic performances at rest than stented bioprostheses, but very few comparisons were performed during exercise. METHODS: Thirty-eight patients with normally functioning stentless (n = 19) or stented (n = 19) bioprostheses were submitted to a maximal ramp upright bicycle exercise test. Valve effective orifice area and mean transvalvular pressure gradient at rest and during peak exercise were successfully measured using Doppler echocardiography in 30 of the 38 patients. RESULTS: At peak exercise, the mean gradient increased significantly less in stentless than in stented bioprostheses (+5 +/- 3 vs. +12 +/- 8 mm Hg; p = 0.002) despite similar increases in mean flow rates (+137 +/- 58 vs. +125 +/- 65 ml/s; p = 0.58); valve area also increased but with no significant difference between groups. Despite this hemodynamic difference, exercise capacity was not significantly different, but left ventricular (LV) mass and function were closer to normal in stentless bioprostheses. Overall, there was a strong inverse relation between the mean gradient during peak exercise and the indexed valve area at rest (r = 0.90). CONCLUSIONS: Hemodynamics during exercise are better in stentless than stented bioprostheses due to the larger resting indexed valve area of stentless bioprostheses. This is associated with beneficial effects with regard to LV mass and function. The relation found between the resting indexed valve area and the gradient during exercise can be used to project the hemodynamic behavior of these bioprostheses at the time of operation. It should thus be useful to select the optimal prosthesis given the patient's body surface area and level of physical activity.

Bioprosthesis↗
PubMed1999

Acute myocardial infarction complicated by hemodynamically unstable bradyarrhythmia: prehospital and ED treatment with atropine.

The purpose of this study was to investigate the therapeutic response to atropine of patients experiencing hemodynamically compromising bradyarrhythmia related to acute myocardial infarction (AMI) in the prehospital (PH) setting and the therapeutic impact of the PH response to atropine on further Emergency Department (ED) care. In addition, the prevalence of AMI in patients presenting with atrioventricular block (AVB) is noted. Retrospective review of PH, emergency department (ED), and hospital records. PH patients, with hemodynamically compromising bradycardia or AVB with evidence of spontaneous circulation, who received atropine as delivered by emergency medical services (EMS) personnel, were used. Urban/suburban fire department-based emergency medical services (EMS) system with on-line medical control serving a population of approximately 1.6 million persons. Hemodynamic instability was defined as the presence of any of the following: ischemic chest pain, dyspnea, syncope, altered mental status, and systolic blood pressure less than 90 mm Hg. Bradycardia was defined as sinus bradycardia, junctional bradycardia, or idioventricular bradycardia (grouped as bradycardia), whereas AVB included first-, second- (types I and II), or third-degree (grouped as AVB). The response that occurred within 1 minute of atropine dosing was recorded as none, partial, complete, or adverse. Comparisons were made between patients with AMI and non-AMI hospital discharge diagnoses. The diagnosis of AMI was confirmed by abnormal elevations in creatinine phosphokinase MB fraction. One hundred seventy-two patients meeting entry criteria were identified. Of these, 131 (76.1%) had complete PH, ED, and hospital records and were used for data analysis. Forty-five patients (34.3%) had a primary hospital discharge diagnosis of AMI; the remaining patients had a non-AMI discharge diagnosis. AMI patients were significantly younger (67 +/- 12 v 73 +/- 13 years, P = .025), were less likely to have a history of heart disease (35.5% v54.7%, P = .038), and were more likely to present with chest pain (68.9% v24.4%, P < .001) or hypotension (60% v37.2%, P = .013) compared with non-AMI patients. Forty-five of 131 patients presented with AVB, of which 25 had a hospital discharge diagnosis of AMI (55.6%). The mean time from first dose of atropine to ED arrival and the total dose of atropine received in the PH setting did not differ between AMI and non-AMI groups (15.2 +/- 7.7 v 16.2 +/- 8.7 minutes, P= .5; and 0.9 +/- 0.49 v 1.0 +/- 0.58 mg, P = .25). The likelihood of achieving normal sinus rhythm in the PH setting did not differ between AMI and non-AMI groups (40% v 18.6%, P = .07). No differences were found between AMI and non-AMI groups in the amount of additional atropine given (1.2 +/- 0.58 v 1.3 +/- 1.1 mg, P = .58) or the use of other resuscitative therapies after ED arrival (isoproterenol, 13.3% v12.8%, P = .93; dopamine, 28.9% v26.7% P = .79; transcutaneous pacing, 26.7% v26.7%, P = .99; transvenous pacing, 8.9% v5.8%, P = .51), with the exception of thrombolytic therapy (24.4% v 0%, P< .001) and cardiac catheterization (22.2% v3.4%, P = .001). Despite a lack of significant difference in achieving a normal sinus rhythm in the prehospital or ED setting, AMI patients were more likely to achieve a normal sinus rhythm over the total course of PH and ED care than non-AMI patients (44.4% v24.4%, P = .019). Hemodynamically unstable (by ACLS criterion) AVB presenting in the PH setting is associated with a hospital diagnosis of AMI in most (55.6%) patients in this study. AMI patients with hemodynamically unstable AVB or bradycardia are no more likely to respond to atropine therapy in the PH setting than patients with non-AMI hospital diagnoses. Finally, although there is no difference in the treatment of compromising AVB or bradycardia received by AMI versus non-AMI patients in the PH or ED setting, AMI patients are more likely to achieve a normal sinus rhythm over the t

Age Distribution↗
PubMed1994

Hemodynamic stress and experimental aortoiliac atherosclerosis.

PURPOSE: Human aortic atherosclerosis is predominantly localized to the infrarenal aorta where flow is bidirectional and wall shear stress oscillates. Similar flow patterns have been related to carotid atherosclerosis. The thoracic aorta is usually spared, where flow and shear stress are unidirectional. We hypothesized that because heart rate and systemic blood pressure modulate flow velocity and shear stress oscillation, both these hemodynamic forces may enhance aortoiliac atherogenesis. METHODS: Eighteen male cynomolgus monkeys were fed an atherogenic diet for 6 months (mean serum cholesterol = 535 +/- 35 mg/dl). Heart rate was determined with 24-hour electrocardiographic telemetry at monthly intervals and blood pressure was measured by direct arterial cannulation. The product of mean heart rate and mean blood pressure was used to define hemodynamic stress for each animal. Atherosclerotic lesion formation at three standard thoracic aortic sites was quantitatively compared with lesion formation at five standard infrarenal aortoiliac locations with computer-assisted morphometry. RESULTS: There was significantly more plaque in the aortoiliac segment than in the thoracic aorta (12.4% +/- 9.0% vs. 6.4% +/- 4.5% area stenosis, p = 0.02). No correlation was found between the degree of serum lipid elevations and lesion formation in either aortic location. Mean heart rate was 113 +/- 18 beats/min (87 to 163 beats/min) and mean blood pressure was 85 +/- 19 mm/Hg (62 to 130 mm Hg). Heart rate and blood pressure alone were not significantly related to lesion formation. A significant correlation was, however, found between hemodynamic stress and maximum lesion thickness (r = 0.47, p < 0.05) in the aortoiliac region but not in the thoracic aorta (r = 0.19, p > 0.10). CONCLUSIONS: This study demonstrates that heart rate and blood pressure exert a mutually potentiating effect on aortoiliac atherosclerosis but not on thoracic aortic atherosclerosis. Regional differences in aortic atherosclerosis may therefore be attributable to the interaction between these hemodynamic forces and the local flow patterns specific to each aortic location. Additional investigation of these hemodynamic factors in relation to human aortic atherosclerosis is warranted.

Animals↗
PubMed1994

Are peroneal artery bypass grafts hemodynamically inferior to other tibial artery bypass grafts?

PURPOSE: Many authors have reported excellent long-term patency rates of peroneal artery bypasses. It has been suggested, however, that the hemodynamic result of the peroneal bypass is inferior to that of other infrapopliteal artery bypasses, making it suboptimal in patients with forefoot ischemic tissue loss. A retrospective review of 118 recent infrainguinal vein grafts (36 peroneal, 27 anterior tibial, 35 posterior tibial, 20 popliteal) was undertaken to assess and compare the hemodynamic results for each group. METHODS: We reviewed the hemodynamic results of 36 peroneal bypass grafts assessed by preoperative and postoperative ankle-brachial index and transmetatarsal pulse volume recording, duplex scan-derived distal graft peak systolic flow velocity, and intraoperatively measured outflow resistance. These results were compared with a concurrent series of anterior tibial, posterior tibial, and popliteal artery bypass grafts. All but one of the infrapopliteal bypass grafts were performed for limb salvage, and 65% of patients had ischemic ulcerations or gangrene. RESULTS: There was no difference in postoperative ankle-brachial index, postoperative transmetatarsal pulse volume recording, peak systolic flow velocity, or measured outflow resistance among the four different outflow groups. All patients with peroneal bypass grafts had healed wounds within a mean follow-up period of 17 months. There were no hemodynamic failures. CONCLUSION: Peroneal artery bypass grafts achieved hemodynamic results equivalent to anterior tibial, posterior tibial, and popliteal artery bypass grafts.

Analysis of Variance↗
PubMed1994

Vein adaptation to the hemodynamic environment of infrainguinal grafts.

PURPOSE: Although arteries appear to remodel in response to changes in hemodynamic parameters such as shear stress, little is known about functioning human vein grafts. This study was designed to explore diameter changes in human saphenous vein grafts after infrainguinal bypass. METHODS: We used duplex ultrasonography to measure hemodynamic variables that might affect the diameter of 48 in situ saphenous vein grafts during the first year after infrainguinal arterial bypass. Volumetric flow rate, average velocity, peak systolic velocity, and vein diameter in the proximal and distal thirds of these grafts were each measured at 1 week and at 3, 6, and 12 months after operation. Veins were divided into three groups based on initial size (1 week after bypass) in the below-knee segment: small, < 3.5 mm diameter; medium, 3.5 to 4 mm diameter; and large, > 4 mm diameter. RESULTS: Distal vein diameters at 1 week for small, medium, and large grafts were 2.9 +/- 0.1, 3.7 +/- 0.1, and 4.3 +/- 0.1 mm, respectively (p < 0.001), but by 12 months these diameters were 3.6 +/- 0.2, 3.8 +/- 0.2, and 3.9 +/- 0.2 mm, respectively (p = 0.54). Large veins decreased in diameter, whereas small veins increased in diameter, as confirmed by linear regression of percent change in diameter versus initial vein graft diameter (r = -0.62, p < 0.001). Volumetric flow rate, peak systolic velocity, and shear stress also tended to approach uniform values over time. Of the hemodynamic variables studied, the best predictor of diameter change was shear stress (linear regression of percent change in diameter vs shear stress, r = 0.67, p < 0.001). Veins with a diameter increase greater than 10% over time had significantly higher initial shear stress than veins with a diameter decrease greater than 10% over time (28.6 +/- 3.8 vs 13.1 +/- 1.8 dynes/cm2, p < 0.01), whereas initial volumetric flow rates in these two groups were similar (135 +/- 23 vs 130 +/- 15 ml/min). CONCLUSIONS: Infrainguinal in situ vein graft diameter, volume flow rate, peak systolic velocity, and shear stress all tend to stabilize at uniform values regardless of the initial vein graft diameter. Of the hemodynamic variables studied, shear stress is most strongly associated with the change in diameter over time. Thus human saphenous vein appears to be capable of adapting to its hemodynamic environment after arterial grafting by modulating diameter to normalize shear stress.

Adaptation, Physiological↗
PubMed1999

Effect of exercise on hemodynamic conditions in the abdominal aorta.

PURPOSE: The beneficial effect of exercise in the retardation of the progression of cardiovascular disease is hypothesized to be caused, at least in part, by the elimination of adverse hemodynamic conditions, including flow recirculation and low wall shear stress. In vitro and in vivo investigations have provided qualitative and limited quantitative information on flow patterns in the abdominal aorta and on the effect of exercise on the elimination of adverse hemodynamic conditions. We used computational fluid mechanics methods to examine the effects of simulated exercise on hemodynamic conditions in an idealized model of the human abdominal aorta. METHODS: A three-dimensional computer model of a healthy human abdominal aorta was created to simulate pulsatile aortic blood flow under conditions of rest and graded exercise. Flow velocity patterns and wall shear stress were computed in the lesion-prone infrarenal aorta, and the effects of exercise were determined. RESULTS: A recirculation zone was observed to form along the posterior wall of the aorta immediately distal to the renal vessels under resting conditions. Low time-averaged wall shear stress was present in this location, along the posterior wall opposite the superior mesenteric artery and along the anterior wall between the superior and inferior mesenteric arteries. Shear stress temporal oscillations, as measured with an oscillatory shear index, were elevated in these regions. Under simulated light exercise conditions, a region of low wall shear stress and high oscillatory shear index remained along the posterior wall immediately distal to the renal arteries. Under simulated moderate exercise conditions, all the regions of low wall shear stress and high oscillatory shear index were eliminated. CONCLUSION: This numeric investigation provided detailed quantitative data on the effect of exercise on hemodynamic conditions in the abdominal aorta. Our results indicated that moderate levels of lower limb exercise are necessary to eliminate the flow reversal and regions of low wall shear stress in the abdominal aorta that exist under resting conditions. The lack of flow reversal and increased wall shear stress during exercise suggest a mechanism by which exercise may promote arterial health, namely with the elimination of adverse hemodynamic conditions.

Aorta, Abdominal↗
PubMed2001

Effects of small doses of prostaglandin E(1) on systemic hemodynamics and jugular venous oxygen saturation during cardiopulmonary bypass.

STUDY OBJECTIVE: To examine the effects of small doses of prostaglandin E(1) (PGE(1)) on systemic hemodynamics and cerebral oxygenation during cardiopulmonary bypass(CPB). DESIGN: Randomized, prospective study. SETTING: Cardiac surgery at Saitama Cardiovascular and Pulmonary Center. PATIENTS: Forty patients who underwent elective coronary artery bypass surgery. INTERVENTIONS: The study was performed at the stable CPB period. Patients were randomly divided into four groups: control group (n = 10) received an infusion of saline, PGE(1) 10 group (n = 10) received an infusion of PGE(1) 10 ng/kg/min, PGE(1) 25 group (n = 10) received an infusion of PGE(1) 25 ng/kg/min, and the PGE(1) 50 group (n = 10) received an infusion of PGE(1) 50 ng/kg/min. MEASUREMENTS: After measuring the baseline partial pressure of the arterial oxygen saturation (SpO(2)), mixed venous oxygen saturation (SvO(2)), and jugular venous oxygen saturation (SjvO(2)), blood gases, and cardiovascular hemodynamic values, PGE(1) was infused intravenously at rate of between 10 and 50 ng/kg/min. PGE(1) infusion continued 30 minutes after the start of drug infusion, and the blood gas analysis and cardiovascular hemodynamic values were simultaneously determined together with the hemodynamic values at 2, 5, 10, 20, and 30 minutes during drug infusion. At 30 minutes after discontinuation of the drug infusion, the blood gas analyses were simultaneously determined together with the hemodynamic values. MAIN RESULTS: Mean arterial pressure (MAP) in PGE(1) 25 and 50 groups was decreased 20 and 30 minutes after the start of PGE(1) infusion compared with the baseline value (p < 0.05). In contrast, SvOm(2) in PGE(1) 25 and 50 groups was increased 20 and 30 minutes after the start of PGE(1) infusion compared with the baseline value (p < 0.05). There was no change in SjO(2) value despite a decrease in MAP during the study. CONCLUSIONS: Cerebral oxygenation estimated by SjvO(2) was maintained despite a decrease in MAP during the administration rate of PGE(1) between 10 and 50 ng/kg/min.

Aged↗
PubMed1998

Hemodynamic changes during a new procedure for regional chemotherapy involving occlusion of the thoracic aorta and inferior vena cava.

STUDY OBJECTIVE: To describe the hemodynamic consequences of a regional chemotherapy procedure involving occlusion of the thoracic aorta and inferior vena cava (IVC) by intraluminal balloons. DESIGN: Prospective study. SETTING: Operating rooms of an academic hospital. PATIENTS: 10 patients with inoperable intraabdominal malignancy. INTERVENTIONS: After the induction of general anesthesia and the insertion of a pulmonary artery catheter the patients underwent the regional chemotherapy procedure. MEASUREMENTS AND MAIN RESULTS: Occlusion of the thoracic aorta induced an increase in blood pressure (BP) and systemic vascular resistance (SVR) (41% +/- 8% and 80% +/- 15% from baseline, respectively), and a 30% +/- 7% decrease in cardiac output (CO). After aortic balloon deflation at the end of the procedure, we observed a decrease in BP to baseline values, decrease in SVR (to 62% +/- 12% below baseline), and increase in CO (to 80% +/- 15% above baseline). Those changes resemble those described during vascular surgery. Isolated occlusion of the IVC before aortic occlusion caused hemodynamic deterioration in only three of 10 patients, suggesting incomplete obstruction or collateral blood flow in others. Occluding the IVC while the aorta was occluded, caused minimal hemodynamic changes. CONCLUSIONS: Independent inflation of the IVC balloon should not be performed routinely because of possible unpredicted hemodynamic instability. Inferior vena cava occlusion should always be performed after complete aortic occlusion, because it is then that it produces negligible hemodynamic consequences. It is possible that a better assessment of IVC occlusion after balloon inflation needs to be done by contrast injection to prevent a possible leak of chemotherapeutic drugs.

Abdominal Neoplasms↗
PubMed2000

Pulmonary thromboendarterectomy in patients with chronic thromboembolic pulmonary hypertension: hemodynamic characteristics and changes.

OBJECTIVE: To see whether degree of pulmonary hypertension or severity of cardiac failure affect the success of pulmonary thromboendarterectomy (PTE) in chronic thromboembolic pulmonary hypertension. METHODS: From May 1996 to June 1999, 33 patients, all in New York Heart Association (NYHA) class 3 or 4 were treated with PTE. Preoperative hemodynamic values were: central venous pressure (CVP) 8+/-6 (1-23), mean pulmonary artery pressure (mPAP) 50+/-10 (30-69), cardiac output (CO) 3.3+/-0.9 (1.8-5.2), pulmonary vascular resistance (PVR) 1056+/-344 (523-1659), and right ventricle ejection fraction (RVEF) 12+/-5 (5-21). To establish whether some hemodynamic or cardiac variables correlate with surgical failure (early death or functional non-success), these patients were divided into a low risk or a high risk group for each variable: CVP (<9 or > or =9), mPAP (<50 or > or =50), CO (> or =3.5 or <3.5), PVR (> or =1100 or <1100), and RVEF (> or = 10 or <10). The duration of 3-4 NYHA class period (<24 or > or = 24 months) was also included in the study. RESULTS: Three patients (9. 1%) died in hospital, one (3.0%) underwent lung transplant shortly after PTE, and in five cases (15.2%) mPAP and PVR at the 3-month follow-up examination corresponded with our definition of functional nonsuccess (mPAP and PVR decreased by less than 40% of preoperative values). One of the five functional nonsuccess patients underwent lung transplant 3 months after the operation and another died 17 months after the operation from a non-related cause. Thus PTE was successful in 24 patients and unsuccessful in nine. None of the hemodynamic variables considered was found to be associated with the disparate outcomes. At the 3-month examination, all surviving patients were in NYHA class 1 or 2 except for three in NYHA class 3. At 2 years, hemodynamic values were: CVP 2+/-2 (0-4), mPAP 16+/-3 (12-21), CO 5.0+/-1.0 (3.4-6.5), PVR 182+/-51 (112-282), and RVEF 35+/-5 (26-40). All differences were significant with respect to baseline values (P<0.001). Preoperative mPAP and RVEF values had a strict linear correlation (R=0.45; P=0.014). CONCLUSIONS: None of the variables considered was correlated with early death or functional nonsuccess. Neither preoperative severity of pulmonary hypertension nor degree of cardiac failure influenced the outcome of the operation. PTE leads to hemodynamic recovery even in very compromised patients.

Adult↗
PubMed2001

Pulmonary thromboendarterectomy--risk factors for early survival and hemodynamic improvement.

OBJECTIVE: Pulmonary thromboendarterectomy (PTE) for chronic thromboembolic pulmonary hypertension is a challenging procedure with a considerable mortality. The aim of this investigation was to identify risk factors influencing mortality and operative results. METHODS: Between October 1995 and August 2000, 69 patients (age 54 years; 34 women; mean New York Heart Association (NYHA) stage 3.4) underwent PTE. The preoperative pulmonary vascular resistance (PVR) was 988+/-554 dynes x s x cm(-5), mean pulmonary artery pressure 50+/-12 mmHg, right atrial pressure (RAP) 11.5+/-4 mmHg. Hospital mortality was 10.1% (n=7/69). Mean postoperative PVR on the 2nd day was 324+/-188 dynes x s x cm(-5). Pulmonary angiography was reviewed for number of involved segments (mean 9.3+/-2) and bronchial arteries diameter (BAD; mean 4.6+/-1.6 mm). A univariate and multivariate analysis was performed to determine preoperative risk factors for hospital death and inadequate hemodynamic improvement. RESULTS: By univariate analysis, mortality was influenced by age (P=0.04), right atrial pressure (P=0.009), NYHA (P=0.02) and the number of angiographically involved segments (P=0.02). Sex, left ventricular function, presence of coronary artery disease and bronchial artery diameter did not show correlation with mortality. Inadequate hemodynamic improvement in a dichotomized analysis (PVR > or =500 dynes x s x cm(-5), n=11, and PVR < 500 dynes x s x cm(-5), n=58), assessed by univariate analysis, was significantly influenced by age (P=0.02), preoperative PVR (P=0.01), NYHA (P=0.002), RAP (P=0.02) and female sex (P=0.02). Multivariate analysis identified age (P=0.1), RAP (P=0.002) and female sex (P=0.007) as risk factors for inferior hemodynamic improvement. CONCLUSIONS: Preoperative parameters can be utilized to assess postoperative mortality and hemodynamic improvement after pulmonary thromboendarterectomy. Patient age and clinical deterioration of pulmonary hypertension are considerable preoperative factors influencing hospital mortality. Inadequate postoperative hemodynamic improvement is affected by severity of disease and female sex.

Adolescent↗
PubMed1995

A comparison of amrinone with sodium nitroprusside for control of hemodynamics during infrarenal abdominal aortic surgery.

OBJECTIVES: The control of hemodynamic changes during surgical resection of abdominal aortic aneurysms (AAA) remains a challenge to anesthesiologists. In the past, hypertensive episodes have been treated with sodium nitroprusside (SNP). However, amrinone may provide some benefits when compared with SNP because of its positive inotropic and vasodilatory properties. Therefore, the purpose of this study was to compare amrinone with SNP for hemodynamic control during AAA surgery. DESIGN: This study was a prospective, randomized investigation. SETTING: This study was performed at a single university hospital. PARTICIPANTS: This study included 20 patients undergoing AAA resection. INTERVENTIONS: After institutional review board approval, participants were randomized to receive either SNP (group N = 10) or amrinone (group A = 10). Both agents were started 10 minutes before aortic cross-clamping and discontinued 10 minutes before unclamping. Anesthesia was induced with thiopental or etomidate and maintained with oxygen, nitrous oxide, isoflurane, fentanyl, and vecuronium. Hemodynamic measurements included heart rate, systolic and diastolic blood pressure, cardiac output, systolic and diastolic pulmonary artery pressure, pulmonary capillary wedge pressure, central venous pressure, mixed venous oxygen saturation, electrocardiogram, and ST-T wave trend analysis. MEASUREMENTS AND MAIN RESULTS: Demographic and clinical characteristics for the two groups were similar. Mixed venous oxygen saturation was significantly lower (p < 0.05) in group N immediately after unclamping. There were no differences between groups for the other measurements studied. There were no episodes of myocardial ischemia in either group. CONCLUSIONS: This study demonstrates that amrinone provides equivalent hemodynamic control to SNP during abdominal aortic aneurysm surgery because it allows moderate reductions in blood pressure without affecting other hemodynamic measurements. Further studies are needed to assess whether patients with poor preoperative left ventricular function would benefit from amrinone management during AAA resection.

Aged↗