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At least 739 records · Page 41Linked to original sources
PubMed1993

Interaction between beta blockers and epinephrine on hemodynamics of spontaneously hypertensive rats.

Hypertensive patients treated with nonselective beta adrenergic blocking agents may show remarkable hemodynamic changes with administration of epinephrine clinically. We have attempted to investigate the effects of the interaction between beta blockers (a nonselective beta blocker, pindolol, and a cardioselective beta blocker, acebutolol) and a solution of 2% lidocaine containing 1:80,000 epinephrine on the hemodynamics of conscious spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY), as compared with the normotensive rats. The blood pressures (systolic and diastolic) and heart rate were measured indirectly by the photoplethysmographic tail cuff method. All drugs were administered intraperitoneally. We found that: (1) epinephrine with pindolol or acebutolol pretreatment did not cause significant hemodynamic changes in WKY; (2) in SHR, epinephrine in combination with pindolol induced remarkable hemodynamic changes (in particular, increase in diastolic blood pressure), which were prevented by phentolamine pretreatment, whereas epinephrine with acebutolol pretreatment induced no significant hemodynamic changes in these animals; (3) epinephrine in combination with pindolol caused pulmonary congestion or edema in SHR; this was confirmed by both quantitative analysis and histological investigations. These results suggest that pindolol blocked both beta 1 and beta 2 receptors, and therefore, this resulted in exaggerated alpha effects of epinephrine, a remarkable systemic vasoconstriction, and pulmonary congestion. In a clinical setting, great caution should be paid to the hypertensive patients, who are being treated with nonselective beta blockers, if epinephrine-containing local anesthetics are administered.

Acebutolol↗
PubMed1977

Intraoperative hemodynamic evaluation of the Björk-Shiley tilting disc aortic valve.

Intraoperative cardiac output and aortic and left ventricular pressures were measured simultaneously in 15 consecutive patients before and after aortic valve replacement (AVR) with the Björk-Shiley tilting disc valve. The predominant lesion in these patients was aortic stenosis. The following hemodynamic indices were calculated: aortic valve area (AVA), determined by Gorlin's formula, effective orifice area, and effective area index. Their applicability as hemodynamic criteria of the immediate hemodynamic performance of the replaced valve is discussed. By every criterion, AVR greatly improved the hemodynamic performance. The effective area index seemed more suitable than the other indices for the intraoperative hemodynamic evaluation of the replaced aortic valve.

Adult↗
PubMed1996

Sequential evaluation of portal venous hemodynamics by Doppler ultrasound in patients with severe acute hepatitis.

OBJECTIVES: Portal hypertension may develop in patients with severe acute hepatitis. Sequential changes of portal venous hemodynamics in acute hepatitis is not well understood. This study evaluated portal hemodynamic changes and prognostic values in patients with severe, acute hepatitis. METHODS: Doppler studies, liver function tests, and virology studies were done in the inclusion, the 3rd month, and the 6th month for patients with severe, acute hepatitis. An indocyanine green clearance was done in the inclusion. Doppler portal hemodynamic studies were done in the hilar area by an average of two measurements. RESULTS: A total of 88 consecutive patients was included. Nine of them died. On initial study, fatalities were generally older patients with more delayed indocyanine green clearance, lower portal vein velocity, lower albumin values, higher bilirubin values, longer prothrombin time, and ascites. Using stepwise logistic regression, portal blood flow and prothrombin time were the two independence prognostic factors. By multiple linear regression, portal blood flow was associated with ascites, and average portal blood velocity was associated with bilirubin. During the hospital days, transient, depressed portal blood velocities followed by a hyperdynamic stage were found in survivors. The portal vein velocity changes for fatalities either were kept at a lower level or had a declining pattern. CONCLUSIONS: Doppler ultrasound detects portal hemodynamic changes for patients with severe, acute hepatitis. Sequential portal hemodynamic studies will be helpful for evaluating patients with severe, acute hepatitis.

Acute Disease↗
PubMedDate not supplied

Occult restrictive hemodynamics after pediatric heart transplantation.

BACKGROUND: Although resting hemodynamics after pediatric heart transplantation are generally within normal limits, we hypothesized that occult restrictive hemodynamics suggesting diastolic dysfunction may be unmasked by acute volume loading (fluid challenge) during cardiac catheterization. We wished to determine the incidence of diastolic dysfunction and to assess whether it progressed over time. METHODS: From 1988 through 1993, a total of 100 fluid challenges were performed at the time of surveillance endomyocardial biopsy in 31 survivors of orthotopic heart transplantation. Cyclosporine-based immunosuppression was used in 16 patients, and FK506 was used in 15 patients. Right heart hemodynamics and cardiac output (thermodilution) were obtained at baseline and after a fluid challenge with 10 ml/kg of normal saline solution. The data were analyzed to determine whether type of immunosuppression or time elapsed since transplantation predicted the response to fluid challenge. RESULTS: Baseline hemodynamics were normal; however, a marked increase in atrial filling pressures occurred after fluid challenge (p < 0.001). Findings were similar in cyclosporine- and FK506-treated patients. Hemodynamic response to fluid challenge was not related to duration of time since transplantation, including studies on patients surviving more than 4 years. CONCLUSIONS: Diastolic dysfunction after heart transplantation is common; however, the abnormalities do not progress in severity, suggesting stable long-term graft function.

Adolescent↗
PubMedDate not supplied

Hemodynamic response to intentionally altered flow continuity of dobutamine and dopamine by an infusion pump in infants.

STUDY OBJECTIVE: To evaluate the effect of an intentional alteration in infusion pump flow continuity on the hemodynamic stability of infants receiving either dobutamine or dopamine. DESIGN: Prospective, open-label study. SETTING: A university-affiliated children's hospital. PATIENTS: Ten hemodynamically stable infants (age 2 wks-10 mo) in intensive care receiving dobutamine (5) or dopamine (5). Three patients received both agents and were studied at independent times. INTERVENTIONS: Dobutamine and dopamine were administered using the Flo-Gard VP pump that delivers an intentional alteration of flow continuity (rate pulse). Heart rate and mean arterial pressure (MAP) were recorded every second. Analysis was based on the measurements obtained from the first 5 minutes on the study pump and the 2 minutes before and after the rate pulse. MEASUREMENTS AND MAIN RESULTS: Although hemodynamic changes in pre- and post-rate pulses were statistically significant (p < 0.05) in some individuals, only one infant had a greater that 10% change in MAP 2 minutes after the rate pulse. Alterations in hemodynamics were not consistent among or within patients. CONCLUSION: In infants requiring dobutamine or dopamine, no clinically significant pharmacodynamic effects were associated with alteration in continuity of drug delivery caused by the single positive rate pulse. Therefore, we conclude there is no contraindication to the use of this infusion pump in hemodynamically stable infants receiving these drugs.

Cardiotonic Agents↗
PubMed1996

Hemodynamic indices of myocardial dysfunction correlate with dipyridamole thallium-201 SPECT.

UNLABELLED: Important differences in hemodynamics and tracer kinetics occur with dipyridamole compared to exercise scintigraphy. To better understand the clinical significance of dipyridamole SPECT 201Tl scintigraphy, we examined the relationships between scintigraphy and clinical, and angiographic and hemodynamic variables in patients with CAD. METHODS: Forty-nine subjects were divided into three study groups. Patients in Groups A (n = 11) and B (n = 20) had a low (<5%) likelihood of CAD. Group A underwent maximal exercise thallium stress testing. Group B underwent thallium dipyridamole scintigraphy. Group C (n = 18) consisted of patients with coronary artery disease who had dipyridamole thallium scintigraphy and cardiac catheterization within 2 wk. Thallium lung-to-myocardial ratio (L/M), left ventricular dilation and perfusion defect site were compared to hemodynamic, clinical and angiographic variables. RESULTS: The Group A L/M ratio of 0.23 +/- 0.05 (mean +/- 1 s.d.) was significantly lower (p < 0.001) compared to the Group B L/M ratio of 0.31 +/- 0.05. In Group C, the UM ratio showed correlation with indices of left ventricular dysfunction including lower resting ejection fraction (p = 0.02, r = 0.83), higher pulmonary capillary wedge pressure (p = 0.01, r = 0.58) and lower cardiac index (p = 0.03, r = 0.54). Left ventricular dilation was associated with hemodynamic changes of ventricular failure including lower resting ejection fraction (p = 0.008, r = 0.88) and higher pulmonary capillary wedge pressure (p = 0.02, r =0.54). Immediate and delayed perfusion defect size showed good correlation with lower resting left ventricular ejection fraction (p = 0.02, r = 0.83, and p = 0.004, r = 0.91, respectively). CONCLUSION: Lung uptake, left ventricular dilation and perfusion defect size show good correlation to hemodynamic indices of resting left ventricular dysfunction. A combination of these factors may be a better predictor of future cardiac events and prognosis.

Cardiac Catheterization↗
PubMed1997

Contrasting effects of urethane, ketamine, and thiopental anesthesia on ethanol-clonidine hemodynamic interaction.

In previous studies, we have shown that ethanol counteracts the hypotensive and sympathoinhibitory effects of clonidine in conscious rats but enhances these responses in alpha-chloralose anesthetized rats. This study investigated whether the latter finding pertains to other anesthetics that act by different mechanisms. The hemodynamic interaction between clonidine and ethanol was evaluated in conscious aortic barodenervated rats and in rats anesthetized with urethane, ketamine, or thiopental. The conscious aortic barodenervated rat was used because it exhibits a greater hypotensive response to clonidine compared with intact (sham-operated) rats. Starting from similar baseline values of blood pressure (BP) and heart rate, clonidine (30 micrograms/kg, iv) elicited similar decreases in BP in all groups of rats (conscious aortic barodenervated or anesthetized). Subsequent administration of ethanol (1 g/kg, iv) counteracted the hypotensive effect of clonidine in conscious aortic barodenervated rats and raised the BP to levels higher than the baseline (preclonidine) values. The pressor effect of ethanol persisted for at least 30 min. In contrast, preadministration of ethanol had no effect on the hypotensive effect of the subsequently administered clonidine. The antagonistic clonidine-ethanol hemodynamic interaction in conscious rats was not altered in urethane-anesthetized rats, both in terms of magnitude and duration. In ketamine-anesthetized rats, a short lasting (< 10 min) pressor effect of ethanol was observed. In contrast, ethanol augmented the hypotensive effect of clonidine in thiopental-anesthetized rats; the hypotensive effect of clonidine became slightly but significantly (p < 0.05) greater after ethanol compared with respective time control values. These findings suggest that the adverse hemodynamic effect of ethanol on centrally mediated hypotensive response is modified by different anesthetics. The antagonistic hemodynamic interaction, demonstrated in conscious rats, is replicated in urethane-anesthetized rats but weakened and reversed in ketamine- and thiopental-anesthetized rats, respectively. Therefore, urethane-anesthetized rats may be used in mechanistic studies on the antagonistic ethanol-clonidine hemodynamic interaction that cannot be undertaken, for technical reasons, in conscious rats.

Anesthetics, Dissociative↗
PubMed1996

Doppler-derived diastolic indices in dilated cardiomyopathy: a hemodynamic evaluation relating pre- and afterload parameters to flow velocity.

OBJECTIVE: To explain the well known finding of a normal early diastolic filling velocity in advanced grade heart failure due to dilated cardiomyopathy (DCM) exclusively by hemodynamics and to relate Doppler-flow velocity parameters to indices representing pre- and afterload. DESIGN: DCM was hypothesized to be a disorder in which pre- and afterload contribute in equal proportion to cardiac insufficiency independently from ischemic impairment of relaxation. PATIENTS: Twenty patients with DCM were enroled in the study after definitive exclusion of coronary and valvular heart disease. METHODS: Diastolic transmitral and transtricuspid Doppler readings and hemodynamic measurements were done simultaneously by two blinded observers. A Swan-Ganz catheter was employed. MAIN RESULTS: Simple and multiple regression analyses revealed early diastolic filling velocity to depend on hemodynamic parameters representing afterload. Pulmonary capillary wedge pressure (PCWP) was found to be directly related to early diastolic filling velocity. An inverse relation between early diastolic filling velocity and parameters representing afterload (systemic vascular resistance and mean arterial pressure) was demonstrated; however the most significant correlation using multiple regression analysis was shown between mitral early diastolic peak-flow velocity (dependent) and PCWP as well as systemic vascular resistance index (independents) (r = 0.75; P < 0.001). Correspondingly, the transtricuspid early diastolic peak-flow velocity was shown to be related to the equilibrium of right atrial pressure and pulmonary vascular resistance index. The atrial diastolic flow velocity parameters were found not to be related to hemodynamic indices. CONCLUSION: A definitive but not one-to-one relationship between early diastolic Doppler-flow indices and hemodynamic parameters was defined. A functional coupling of pre- and afterload can be considered the main determinant of early diastolic filling velocity in DCM.

Adult↗
PubMed1997

[The treatment of the cardiac patient in dentistry and oromaxillofacial surgery. II. The practical management of patients with hemodynamic pathologies].

When odontostomatological or surgical treatment is performed we suggest, in a first phase, to distinguish cardiac patients from the others. In a second phase a careful nosological diagnosis will be performed. Consequently, patients' medical history plays a fundamental role in both diagnostic phases. In this article the authors present the results of several years of research carried out to obtain a correct clinical and therapeutic approach for clinical and surgical Odontostomatology. After an introduction on the clinical features of heart hemodynamic pathologies the most important clinical cases are discussed: like, for example, acardiohemia, valvulopathies and heart decompensation. The principal diacritic features of hemodynamic diseases are illustrated. Essential hypertension (borderline and resident) is a sort of disease not directly related to hemodynamics pathology. Moreover a lot of clinical studies find in heart hemodynamic pathologies the principal problem caused by hypertension on heart physiology. Consequently the authors describe essential hypertension in the same part of pathologies commonly known as heart hemodynamic pathologies. In the last phase the authors illustrate the most opportune therapeutic steps corresponding to the principal pathologies above-described. These matters were dealt with from an odontostomatological point of view. The results obtained suggest the necessity of keeping to the management that was described. Actually a low percentage of accidents occurred only when the above-mentioned clinical processes were completely performed.

Dental Care for Chronically Ill↗
PubMed1997

Invasive evaluation of mitral regurgitation: the importance of hemodynamic measurements during exercise.

BACKGROUND AND AIMS OF THE STUDY: In patients with mitral regurgitation, left ventricular angiography is usually performed to grade the regurgitation. This is a semi-quantitative method which gives some information related to the regurgitant volume at a certain time. The aim of our study was to evaluate the benefits of invasive hemodynamic examinations during stress. Patients with mitral regurgitation according to Doppler color flow mapping, and regurgitation of no more than grade 2+ according to left ventricular angiography, were of special interest. METHODS: One hundred and four consecutive patients were examined with transesophageal echocardiography (TEE), left ventricular angiography and cardiac catheterization during rest and during hemodynamic stress. RESULTS: All patients had mitral regurgitation according to Doppler color flow mapping. Thirty eight patients had a mitral regurgitation of grade 0, 1+ or 2+ according to left ventricular angiography. Of these, seven had a resting v-wave < or = 25 mmHg, and a v wave > or = 50 mmHg during stress. When these seven patients were compared with those with severe grade 3+ and 4+ regurgitation, there was a significant difference between the v-wave at rest (p = 0.02) but no significant difference during stress (p = 0.42). CONCLUSIONS: Mitral regurgitation is a dynamic lesion, the complete assessment of which cannot be obtained from a single measure during one hemodynamic situation. Additional information from v-wave recordings during hemodynamic stress identified a subgroup of patients who had near-normal pressures at rest, but whose v-wave measurements during stress did not differ significantly from those of patients with severe angiographically assessed regurgitation (grades 3+ and 4+). In patients with only minor mitral regurgitation which is suspected to contribute to their clinical symptoms, the monitoring of invasive hemodynamic parameters during stress is important.

Adult↗
PubMed1997

Hemostatic and hemodynamic effects of vasopressin analogue DDAVP in patients with cirrhosis.

Desmopressin (DDAVP), a synthetic analogue of vasopressin, has been shown to improve the bleeding time in patients with cirrhosis. The duration of this effect and the hemodynamic changes associated with DDAVP have not been studied so far. To evaluate these issues, 14 cirrhotics with portal hypertension were studied in basal conditions and after DDAVP (0.3 uk/kg). In 8 patients, hemostatic tests were done at basal conditions and 1, 3, 6 and 24 hs after drug administration. In the remaining 6 patients, mean arterial pressure, cardiac output, portal and femoral blood flows were evaluated. Hemodynamic parameters were measured by Doppler ultrasound. DDVP caused a marked decrease in bleeding time at 1, 3, 6 and 24 hs (14 +/- 9 vs 8 +/- 3, 7 +/- 4, 6 +/- 4 and 8 +/- 4 min, respectively); the decrease was maximal and statistically significant at 6 hs (55 +/- 15%, p < 0.02) after DDAVP infusion. Bleeding time reduction was observed in every patient studied. In the hemodynamic study, DDAVP caused a mild but significant decrease in mean arterial pressure (12 +/- 8%, p < 0.05); no significant changes were observed in the rest of hemodynamic parameters studied. These findings show that DDAVP can be used to shorten the bleeding time for a period of at least 24 hs in patients with cirrhosis, without deleterious hemodynamic effects. This beneficial effect may be of potential relevance in the medical management of patients with chronic liver diseases.

Bleeding Time↗
PubMed1997

[Conn's syndrome. Study of systemic cardiovascular hemodynamics after medical treatment with spironolactone and after surgical treatment].

OBJECTIVES: Assess hemodynamic effect of Conn's syndrome in order to better prepare patients for surgical resection of their adenoma. PATIENTS AND METHODS: Hemodynamic investigations were conducted before any treatment in 13 patients with Conn's syndrome. Results were compared with those in 13 control subjects with permanent primary hypertension. In the 13 patients with Conn's syndrome, the same hemodynamic parameters were studied in 13 after drug therapy using spironolactone and in 8 after surgery. RESULTS: Hypertension was associated with a significant increase in stroke volume and a non-significant increase in cardiac index. Blood pressure normalized after sprironolactone and after surgery in parallel with a significant decrease in blood volume. DISCUSSION: These hemodynamic disorders in Conn's disease patients suggest that the increase in stroke volume is a consequence of increased venous return and more likely, in myocardium contractility or a combination of both. CONCLUSION: These hemodynamic characteristics of Conn's disease should be useful in guiding monitoring schemes for these patients in the perioperative period.

Adolescent↗
PubMed1998

Substantially attenuated hemodynamic responses to Escherichia coli-derived vascular endothelial growth factor given by intravenous infusion compared with bolus injection.

Vascular endothelial growth factor (VEGF) produces beneficial angiogenesis in animal models of coronary and peripheral ischemia. However, intravenous bolus injection of Chinese hamster ovary cell (CHO)-derived VEGF produces adverse effects on hemodynamics. The present study examined pharmacokinetic and hemodynamic responses to Escherichia coli-derived VEGF, which will be used in clinical patients, compared with responses to CHO-derived VEGF, and tested whether intravenous infusion of E. coli-derived VEGF attenuates the hemodynamic responses compared with the responses observed with intravenous bolus injection. Hemodynamic parameters were measured before and after administration of VEGF in conscious, instrumented rats. Intravenous injection of both CHO- and E. coli-derived VEGF produced a similar maximal reduction in arterial pressure, although E. coli-derived VEGF exhibited less of a depressor effect in the initial phase after injection. Either infusion or injection of E. coli-derived VEGF caused hypotension, tachycardia and reduced cardiac output and stroke volume, which were significantly attenuated when given by infusion compared with injection. The maximal hypotensive and tachycardiac responses to infusion were decreased by 50 to 60% compared with those responses observed after injection. Cardiac output was maximally reduced by 34% after injection, but only 18% after infusion. A sustained elevation in systemic vascular resistance observed after injection was avoided after infusion. Thus, the hemodynamic side effects of VEGF administration can be substantially attenuated by controlling the rate of VEGF infusion. The data indicate that infusion, instead of bolus injection, is a more appropriate regimen for VEGF administration.

Animals↗
PubMed1998

Short-term hemodynamic effects of DDD pacing from ventricular apex, right ventricular outflow tract and proximal septum.

Recently, short-term hemodynamic benefits of right ventricular outflow tract (RVOT) or proximal septum (His bundle area) pacing have been reported in comparison with traditional apical stimulation in preliminary investigations. The purpose of the present study was to compare the hemodynamics obtained during DDD pacing from ventricular apex, RVOT and proximal septum in patients with normal left ventricular function. A simultaneous hemodynamic and Doppler-echocardiographic study was performed in 21 patients (age 67 +/- 7 years) with sick-sinus syndrome (8 pts) or 2nd-3rd degree atrioventricular (AV) block (13 pts). The three stimulation sites were randomized and pacing was applied at an identical rate (84 +/- 5 beats/min) and at a constant AV delay (150 ms). Electrocardiographic, hemodynamic and Doppler-echocardiographic investigations were performed during stimulation from each site. The QRS duration did not show significant differences during DDD pacing from ventricular apex, RVOT and proximal septum. The hemodynamic measurements (systemic pressures, mean pulmonary wedge pressure, pulmonary pressures, right ventricular end-diastolic pressure, mean right atrial pressure, cardiac index, systemic vascular resistance and arteriovenous O2 difference) did not show significant differences during pacing from the three sites. Moreover, no significant differences were observed for the Doppler-echocardiographic measurements of systolic function (aortic stroke distance, left ventricular ejection fraction) and diastolic function (isovolumetric relaxion time, mitral E/A ratio, deceleration rate of the E wave). The results suggest that in patients with normal left ventricular function DDD pacing from RVOT or proximal septum does not improve cardiac function with regard to apical pacing.

Aged↗
PubMed1998

[Hemodynamic effect of plasma DNA].

To reveal the hemodynamic effect of plasma DNA, the authors measured the concentrations of plasma DNA, the length of its molecular fragments, and hemodynamic resistance/Toms effect. The Toms effect was detected in all blood samples from 10 healthy donors and 39 patients without acute stroke caused by atherosclerosis of the head great arteries with and without arterial hypertension. There was a clear inverse relationships between the plasma concentrations of DNA which had only long-molecular fragments in healthy persons and the hemodynamic resistance of its blood flow samples. The patient blood plasma had significant increased DNA concentrations but their molecular fragments were long and short. Inverse relationships between the plasma DNA concentration and the hemodynamic resistance of the patients' blood flow samples had a less correlation coefficient due to the high proportion of short DNA molecular fragments. The Toms effect was shown in the DNA solution prepared only from human funic blood where the DNA molecular fragments were long. The Toms effect was absent in the solutions prepared from the commercial cattle or salmon sperm DNA which contained shorter DNA molecular fragments. It is concluded that plasma DNA has a hemodynamic effect and the origin of long-molecular fragments of DNA which is typical for healthy young persons and short DNA molecular fragments that additionally appear in patients with vascular disorders is different.

Acute Disease↗
PubMed1998

Small rosarylike infarctions in the centrum ovale suggest hemodynamic failure.

BACKGROUND AND PURPOSE: Lesions in the centrum ovale may be classified as microangiopathic (lacunar) lesions and hemodynamic infarctions. To distinguish between them, a size of more than 2 cm has been postulated for hemodynamic infarctions. The reliability of this criterion was assessed with MR imaging. METHODS: In 16 patients with unilateral or bilateral occlusion or high-grade stenosis of the internal carotid artery (ICA), CO2 testing revealed an ipsilateral hemodynamic failure. Each hemisphere in these patients was assessed separately for the presence and size of centrum ovale lesions. RESULTS: Five of the 16 patients suffered from large cortical infarctions with a probable embolic pathogenesis. In the remaining 11 patients (22 hemispheres), a hemodynamic failure was found in 15 hemispheres, due to occlusion (13 hemispheres) or high-grade ICA stenosis (two hemispheres). MR imaging revealed centrum ovale infarctions with a size of more than 2 cm in three of the 15 hemispheres. In eight hemispheres, multiple small lesions (< 1.5 cm; three to 30 per hemisphere) could be found with a rosarylike or sickle-shaped distribution. In none of these eight cases did MR images show lacunar infarctions in the typical regions of the brain. CONCLUSION: Our results favor the assumption that the MR finding of multiple small (< 1.5 cm) rosarylike lesions in the centrum ovale seems to be typical in patients with hemodynamic failure due to severe ICA disease.

Adult↗
PubMedDate not supplied

[Hemodynamic evaluation in acute myocardial infarct. Application to the treatment of contractile insufficiency syndromes of the left ventricle].

Even though the coronary care units have reduced to a minimum the mortality due to arrhythmias, the syndromes of left ventricular failure are responsible for the greatest part of hospital deaths in patients with acute myocardial infarction. The poor results depend upon the extensive destruction of left ventricular mass. The management in these cases should be directed to improve the performance of viable muscle as well as to preserve thejeopardized ischemic myocardium that is potentially viable. These goals may be adequately pursued by continuous hemodynamic characterization of left ventricular function. The experience of the Coronary Care Unit of the Instituto Nacional de Cardiología de México in the study of 30 of these patients is presented. Hemodynamic evaluations were performed by means of a Swan-Ganz catheter and cardiac output determinations by the thermodilution technique. The studies may be performed with a minimum of risk. Central venous pressure measurements do not adequately indicate the status of the left ventricle. Its function may be evaluated by the use of end diastolic pulmonary artery pressure which reflects, quite accurately, the left ventricular filling pressure in these patients. Continuous hemodynamic monitorization facilitates the proper manipulation of the determinants of ventricular performance (preload, afterload, cardiac rate and contractility) and permits an attempt to improve the balance between available oxygen and myocardial oxygen requirements. Hemodynamic studies and ventricular function curves are presented in selected patients with acute myocardial infarction. The mortality due to left ventricular failure and cardiogenic shock in patients with acute myocardial infarction remains extremely high. However, it is only through the early recognition by continuous hemodynamic monitorization and the aggressive management of the patient with incipient left ventricular failure that the number of survivors may be increased.

Female↗
PubMed1999

Modeling the hemodynamic response in single-trial functional MRI experiments.

Today, most studies of cognitive processes using functional MRI (fMRI) experiments adopt a single-trial design. Highly flexible stimulation paradigms require new statistical models in which not only the activation amount but also the time course of the measured hemodynamic response is analyzed. Most previous approaches have been based on a linear regression context and have introduced hemodynamic model functions to improve the signal detection. In this report a nonlinear regression context is derived, from which shape parameters for the hemodynamic response are obtained per trial and per region of interest. These parameters allow the investigation of stimulus-induced shape variations of the hemodynamic response. By embedding the estimation into a robust statistical framework and rigorously analyzing the spatiotemporal interactions in the fMRI data, it is possible to derive statistically valid descriptions of single hemodynamic responses. The model, estimation algorithm, validation, and an example analysis from a single-trial fMRI study are reported. Magn Reson Med 42:787-797, 1999.

Algorithms↗