Biomedical subjects

S Aakhus

Publications and source records attributed to S Aakhus.

At least 19 recordsLinked to original sources

PubMed2001

Regional myocardial systolic function during acute myocardial ischemia assessed by strain Doppler echocardiography.

OBJECTIVES: We sought to evaluate if echocardiographic strain measurements could detect acute myocardial ischemia, and to compare this new method with myocardial velocity measurements and wall motion score index. BACKGROUND: Tissue Doppler echocardiography (TDE) is a promising method for assessing regional myocardial function. However, myocardial velocities measured by tissue Doppler echocardiography (TDE) vary throughout the left ventricle (LV) because of tethering effects from adjacent tissue. Strain Doppler echocardiography (SDE) is a new tool for measuring regional myocardial deformation excluding the effect of adjacent myocardial tissue. METHODS: Seventeen patients undergoing angioplasty of the left anterior descending coronary artery (LAD) were studied. Left ventricular longitudinal wall motion was assessed by TDE and SDE from the apical four-chamber view before, during and after angioplasty from multiple myocardial segments simultaneously. RESULTS: Systolic strain values were uniformly distributed in the different nonischemic LV segments, whereas systolic velocities decreased from basis to apex. During LAD occlusion, strain measurement showed expansion in the apical septal segment in 16 of 17 patients (7.5 +/- 6.5% vs. -17.7 +/- 7.2%, p < 0.001) and reduced compression in the mid-septal segment (p < 0.05) compared with baseline. Segments not supplied by LAD remained unchanged. Tissue Doppler echocardiography showed reduced velocities in all septal segments (p < 0.05) during angioplasty even though LAD does not supply the basal septal segment. Negative systolic velocities were present in 11 of 17 patients. Wall motion score index increased during ischemia (1.3 +/- 0.4, p < 0.05). CONCLUSIONS: The new SDE approach might be a more accurate marker than TDE for detecting systolic regional myocardial dysfunction induced by LAD occlusion.

Aged↗

PubMed2001

Myocardial performance after transmyocardial revascularization with CO(2)laser. A dobutamine stress echocardiographic study.

AIMS: Transmyocardial laser revascularization is a treatment for patients with severe angina pectoris not eligible for conventional revascularization. The effects on myocardial function and reversible ischaemia have not been clarified. METHODS AND RESULTS: One hundred patients with refractory angina not eligible for conventional revascularization were randomized 1:1 to receive continued optimal medical treatment or transmyocardial revascularization with CO(2)laser in addition to medical treatment. Dobutamine stress echocardiography examinations were performed at baseline and at 3 and 12 months after randomization. The effects of transmyocardial revascularization on myocardial function and reversible ischaemia were assessed by visual interpretation of cineloops at rest and during stress in a 16-segment model. After transmyocardial revascularization resting left ventricular wall motion abnormalities increased (P<0.01), whereas wall motion during dobutamine stimulation remained unchanged. The number of probably non-viable segments increased (P<0.01) with a corresponding decrease in the number of ischaemic segments. Fewer patients had the dobutamine infusion discontinued because of chest pain after transmyocardial revascularization with laser, but the chest pain threshold did not increase significantly. CONCLUSION: Following transmyocardial revascularization, resting wall motion abnormalities worsened, wall motion abnormalities during dobutamine stimulation remained unchanged and the number of probably non-viable segments increased.

Angina Pectoris↗

PubMed2001

Metabolic cardiovascular syndrome after renal transplantation.

BACKGROUND: Cardiovascular disease (CVD) is the major cause of death in renal transplant recipients. Traditional risk factors like hypertension, dyslipidaemia and diabetes mellitus are common, but cannot completely account for the high prevalence of CVD in this population. The aim of the present study was to assess whether post-transplant glucose intolerance, defined as post-transplant diabetes mellitus, impaired glucose tolerance, or impaired fasting glucose, is associated with metabolic disturbances known to increase risk of cardiovascular disease, similar to what has been observed in the general population. METHODS: One hundred and seventy-three consecutive patients were prospectively examined 10 weeks after transplantation. An oral glucose tolerance test was completed in 167 patients. Questionnaires, medical records, and the results of various blood tests were used to evaluate a number of known cardiovascular risk factors in all patients. RESULTS: Glucose intolerance was present in about one-half the recipients and was associated with age, a positive family history of ischaemic heart disease, acute rejection, higher levels of serum triglycerides, apolipoprotein B and 2-h insulin, and lower levels of serum HDL cholesterol. After adjustment for age and sex, lower HDL cholesterol (P=0.005), higher serum triglycerides (P<0.001), apolipoprotein B (P=0.039) and 2-h insulin (P<0.001) were still associated with post-transplant glucose intolerance. CONCLUSIONS: Ten weeks after renal transplantation glucose intolerance is associated with a clustering of cardiovascular risk factors and metabolic abnormalities, consistent with a post-transplant metabolic cardiovascular syndrome.

Adult↗

PubMed2000

Cardiac output measurements during cross-clamping of the descending thoracic aorta in pigs. A comparison between transit-time ultrasound, thermodilution and pulsed Doppler ultrasound.

BACKGROUND: Cross-clamping of the descending thoracic aorta (XC) induces an increase in cardiac output (CO). The intention of this study was to evaluate the high CO during XC by the use of clinically available methods (thermodilution and pulsed Doppler ultrasound) compared to transit-time ultrasound flowmetry of the ascending aorta as the gold standard. METHOD: Ten pigs were anaesthetised with ketamine and fentanyl. The descending thoracic aorta was cross-clamped for 30 min, and cardiac output was measured with pulmonary artery thermodilution technique, pulsed Doppler ultrasound on the aortic annulus and transit-time ultrasound flowmetry of the ascending aorta. RESULTS: At 15 min following XC, CO increased from 1.7 l/min to 4.6 l/min measured with transit-time ultrasound (P<0.05). With thermodilution technique, CO increased from 2.6ll/min to 5.7 l/min (P<0.05), and from 2.4 l/min to 6.0 l/min measured with Doppler ultrasound (P<0.05). There was an increase in mean arterial pressure of 81% and heart rate increased 76% (P<0.05). CONCLUSION: XC of the descending thoracic aorta induces an increase in CO of 171%. Thermodilution and pulsed Doppler ultrasound are reliable methods for detecting high cardiac output during thoracic aortic surgery.

Animals↗

PubMed2000

Acute regional myocardial ischemia identified by 2-dimensional multiregion tissue Doppler imaging technique.

BACKGROUND AND OBJECTIVE: Tissue Doppler echocardiography (TDE) is a promising method for the assessment of regional myocardial function, but pulsed TDE does not provide quantitative data from multiple regions simultaneously. This feature is important for the objective assessment of regional differences in myocardial function. In the present study, we investigated a new off-line TDE method that provides quantitative pulsed velocity data from an unlimited number of regions selected within a 2-dimensional (2D) image. The goal of the study was to determine the ability of this new approach to quantify regional myocardial function during acute myocardial ischemia induced by balloon angioplasty. METHODS: Twenty-two patients undergoing angioplasty of the left anterior descending coronary artery (LAD) were studied. Left ventricular longitudinal wall motion was assessed by 2D TDE from the apical 4-chamber view before, during, and after angioplasty. Images were sampled at a rate of 69 +/- 15 frames/s, and the off-line analysis allowed simultaneous measurement of velocities in multiple myocardial segments. RESULTS: There were 3 major alterations in the systolic velocity pattern during LAD occlusion. Peak early systolic velocities along the apical septum were significantly reduced during LAD occlusion (2.8 +/- 1.2 cm/s to 0.6 +/- 1.7 cm/s, P <.001). Myocardial velocities in mid systole suggested paradoxical wall motion (1.0 +/- 1.2 cm/s to -0.8 +/- 0.9 cm/s, P <.001). When comparing the ischemic regions of the left ventricle with the nonischemic regions, each patient demonstrated lower myocardial systolic velocities in the ischemic region. Furthermore, during early diastole, the wall motion of the ischemic segments showed a postsystolic contraction pattern with velocities changing from -0.9 +/- 1.0 cm/s to 1.9 +/- 1.3 cm/s (P <.001). CONCLUSION: This new 2D TDE approach is able to quantify detailed myocardial velocity profiles from multiple regions simultaneously. Single-beat comparisons of ischemic and nonischemic regions might enhance the sensitivity for diagnosing ischemic heart disease. Reversed systolic wall motion during midsystole and marked positive velocity during early diastole might be new and important markers of myocardial wall ischemia.

Aged↗

PubMed2000

Sublingual nitroglycerin delays arterial wave reflections despite increased aortic "stiffness" in patients with hypertension: a Doppler echocardiography study.

Venodilatation with consequent reduction in left ventricular filling and end-diastolic wall stress is an important mechanism for the beneficial effects of nitroglycerin in ischemic heart disease and in left ventricular failure. The effects of sublingual nitroglycerin on arterial pulsatile hemodynamics are less well defined. Doppler echocardiography and the calibrated subclavian artery pulse tracing were used to assess hemodynamics in subjects with sustained arterial hypertension (n = 25) before and 5 to 10 minutes after sublingual deposition of 0.5 mg glyceryl trinitrate. Aortic characteristic impedance was calculated by averaging the modulus of the input impedance (ratio of pressure to flow) at high frequencies and by calculating the ratio of pressure and flow increments during upstroke. The pressure wave was split into forward and backward components, and the reflection coefficient (the ratio of backward to forward pressures) was calculated. Parameters of the arterial bed were estimated by using 2- and 3-element Windkessel models. Nitroglycerin delayed the return of arterial wave reflections by 17% (P =.02) and increased aortic characteristic impedance by 20% (P =. 01), but it did not influence total arterial compliance. Mean arterial pressure decreased 7% (P =.0001), but pulse pressure did not change. Stroke volume and the acceleration time of aortic root flow decreased by 13% (P =.0001) and 8% (P =.01), respectively. Cardiac output decreased 7% (P =.01), despite an increase in heart rate of 10% (P =.0001). Peripheral resistance tended to decrease (4%, P =.06). Thus, in subjects with sustained hypertension, sublingual nitroglycerin dilates peripheral, predominantly muscular arteries with a subsequent delayed return of reflected pressure waves. Reflex activation of the sympathetic nervous system with consequent increased acceleration of left ventricular ejection seems to counteract the effect of reduced mean arterial pressure (distending pressure) with respect to the "stiffness" of the aorta.

Adult↗

PubMed1999

[Cardiovascular disease after kidney transplantation].

Norwegian renal transplant recipients have a high prevalence of cardiovascular disease. In this group of patients cardiovascular disease causes three out of four deaths. Well-known risk factors such as hypertension, dyslipidemia, impaired glucose tolerance and diabetes mellitus are common in renal transplant recipients, but these factors cannot fully explain the high cardiovascular morbidity and mortality. Atherosclerotic disease and left ventricular hypertrophy are highly prevalent in uremic patients before transplantation. Hyperhomocysteinemia, elevated levels of advanced glycosylated end products, and immunosuppressive medication may also accelerate the atherosclerotic process. Until results from controlled trials on the effect of lipid-lowering therapy in renal transplant recipients are available, treatment decisions must be based on studies in non-transplanted patients. Every patient should be treated individually with the overall risk pattern taken into account.

Cardiovascular Diseases↗

PubMed1999

Reversal of intraventricular flow propagation during isovolumic relaxation: A marker of anterior wall dysfunction.

BACKGROUND: Myocardial infarction induces left ventricular (LV) wall motion abnormalities during isovolumic relaxation (IVR) and may potentially alter intraventricular flow during this period. This study evaluated whether 2-dimensional color Doppler measurements of intraventricular flow during IVR were able to identify LV dysfunction caused by coronary artery disease. METHODS: Patients with single-vessel coronary artery disease and posterior wall infarction (21 patients) or anterior wall infarction (27 patients) were included. Eighteen healthy persons served as a control group. LV function was examined by 2-dimensional echocardiography, 2-dimensional color Doppler, and pulsed Doppler techniques. RESULTS: All normal persons (23.6 +/- 10.9 cm/s) and patients with posterior infarction (19.6 +/- 9.3 cm/s) had flow propagation towards LV apex during IVR. Patients with anterior wall infarction had reversed flow direction (-12.2 +/- 8.7 cm/s, P <.001). The echocardiographic wall motion score index of the 4 apical segments correlated well with flow velocities (r = -0.78, P <.001). CONCLUSION: Reversed flow propagation during IVR may become a sensitive clinical marker of regional ischemia.

Analysis of Variance↗

PubMed1999

Cardiovascular morbidity and risk factors in renal transplant patients.

BACKGROUND: Cardiovascular disease is now the major cause of death in renal transplant patients. This study aimed to assess the prevalence of cardiovascular disease in stable renal transplant patients as compared with the general background population, and to assess risk factors for cardiovascular disease in this patient group. METHODS: A cross-sectional multicentre study comprising 406 stable renal transplant patients (age 47+/-16 years, 60% males, 71% taking cyclosporin A) were assessed clinically and biochemically 48 months (median) after transplantation and compared with the general population. Multivariate analysis was used to assess the relation between cardiovascular disease and risk factors. RESULTS: Hypertension was present in 55% of males and 34% of females (P<0.001), in 51% with cyclosporin A and in 33% without (P<0.001). Ischaemic heart disease (i.e. angina pectoris and/or previous myocardial infarction) was present in 14% (males: 18%, females: 10%, P<0.05) and in 24% of diabetics vs 12% of non-diabetics (P<0.01). Cerebro- and peripheral vascular disease was found in 3% and 4%, respectively. Odds ratio for angina pectoris (patients vs general population) was: in age group 40-49 years (males/females), 12/16; 50-59 years, 6/4; 60-69 years, 3/4. Ischaemic heart disease was, besides age and gender, independently associated with total cholesterol (P<0.01), and peripheral vascular disease to systolic blood pressure (P<0.01). CONCLUSIONS: Cardiovascular disease is highly prevalent in renal transplant patients, and is independently associated with age, gender, total cholesterol and systolic blood pressure.

Adult↗

PubMed1999

Total arterial compliance in ambulatory hypertension during selective beta1-adrenergic receptor blockade and angiotensin-converting enzyme inhibition.

Aortic root flow and pressure estimates were obtained noninvasively with Doppler echocardiography and calibrated subclavian artery pulse tracing in 30 subjects with ambulatory hypertension in a randomized, crossover study with 4 weeks' treatment and washout periods. Total arterial compliance, assessed by use of a three-element Windkessel model of the arterial tree, increased 42% with atenolol (50-100 mg once daily), and 7% (p = NS) with captopril (25-50 mg twice daily). Atenolol reduced mean arterial pressure by 15%, heart rate by 22%, and cardiac output by 14%, and increased acceleration time of aortic root flow by 17% and stroke volume and ejection time each by 11%. Captopril reduced mean arterial pressure and total peripheral resistance each by 7%. Acceleration time of aortic root flow, ejection time, heart rate, stroke volume, and cardiac output were not significantly changed by captopril. We conclude that total arterial compliance, at the operational blood pressure, increases during selective beta1-adrenergic receptor blockade in subjects with ambulatory hypertension. Although the main mechanism may be a reduction in mean arterial pressure, it should be considered whether reduced heart rate may play an additional role. The nonsignificant increase in total arterial compliance during angiotensin-converting enzyme inhibition may primarily be a consequence of a modest reduction of the mean arterial pressure.

Adrenergic Antagonists↗

PubMed1998

Left ventricular volumes assessed by different new three-dimensional echocardiographic methods and ordinary biplane technique.

UNLABELLED: Three-dimensional (3D) echocardiography may overcome the problems with inadequate accuracy and reproducibility of 2D volume measurements of the left ventricle. AIMS: To establish the in vitro accuracy and reproducibility of two new methods for 3D echocardiographic volume determination as compared to biplane measurements. METHODS: Validation of volume measurements by a multiplane 3D method was performed on asymmetric latex phantoms (n = 8, true volumes 45-304 ml) using rotational acquisition of 90 image planes. Porcine agarose-filled asymmetrical left ventricles (n = 7, true volumes 34-280 ml) were measured by the same multiplane 3D method based on images acquired by probe rotation axis perpendicular (A) and parallel (B) to the ventricular long axis. Ventricular volumes were also obtained by a simplified 3D system using only the three standard apical views (C) and by the ordinary biplane Simpson's method (D). RESULTS: On latex phantoms systematic deviation from true volumes by multiplane 3D was less than 2%, and 95% variability of individual measurements from this mean was +/- 4.9%. For accuracy on left ventricles, systematic bias was small with all the methods (< 5%), but 95% variability of individual measurements was +/- 9.0%, 15.4%, 18.8% and 41.3% of true volumes for methods A-D respectively. Corresponding results in the same range were obtained for inter- and intraobserver variability. CONCLUSION: Individual in vitro volume estimates of left ventricles are of similar quality using apical multiplane or apical triplane 3D echocardiography. Both methods were superior to the ordinary apical biplane method, but inferior to multiplane 3D method with the probe directed perpendicular to the ventricular long axis.

Animals↗

PubMed1998

Influence of body size and left ventricular ejection dynamics on total arterial compliance determined using Doppler echocardiography and subclavian artery pulse tracings in healthy humans.

The aim was to investigate determinants of total arterial compliance in healthy humans. Estimates of aortic root pressures and flow were obtained non-invasively with the calibrated subclavian artery pulse tracing and Doppler echocardiography in 37 males (27-76 years) and 45 females (20-77 years). Total arterial compliance, estimated using a three-element vascular model, correlated positively with body height (r = 0.45, p < 0.01) and acceleration time of aortic root flow (r = 0.32, p < 0.01) and inversely with age (r = -0.34, p < 0.05), heart rate (r = -0.33, p < 0.01), and mean arterial pressure (r = -0.51, p < 0.01). Multivariate analysis indicated that height and heart rate contributed most to the prediction of total arterial compliance. The inclusion of mean arterial pressure within the model significantly reduced the contribution of age, but not that of body height and heart rate. After adjustment for height and heart rate, total arterial compliance did not differ significantly between gender. Thus, total arterial compliance, as assessed in this study, seems to reflect both arterial capacity and viscoelastic properties of the arterial wall. Differences in body size, heart rate and mean arterial pressure should be considered when comparing total arterial compliance in different groups.

Adult↗

PubMed1997

How does computer-assisted digital wall motion analysis influence observer agreement and diagnostic accuracy during stress echocardiography?

This study assessed interobserver and intraobserver variation and diagnostic accuracy during 25 dipyridamole stress echocardiography tests interpreted with different analysis systems: a) computer display of high frame rate digital cineloops (47 frames/s); b) computer display of lower frame rate digital cineloops (24 frames/s); and c) videotape recordings. The majority of the patients (84%) had documented coronary artery disease with baseline wall motion abnormalities due to previous myocardial infarctions and/or coronary bypass surgery, thus comprising a population with difficult interpretation of stress echocardiography. Diagnostic accuracy was assessed using coronary angiography as reference method. Interobserver and intraobserver agreement was highest when analysis was performed from computer-displayed cineloops, 96 and 92%, respectively, compared to 84 and 80% respectively, using videotape recordings. Sensitivity for identification of coronary artery stenosis was similar using digital cineloops with high frame rate or videotape recordings (67% to 80% for both systems), and tended to be lower using cineloops with lower frame rate for analysis (53%). Inter- and intraobserver differences for wall motion score index were not significantly influenced by the analysis system. We conclude that computer assisted analysis with high frame rate of the displayed cineloops provides optimal observer agreement and diagnostic accuracy in the same range as videotape analysis in patients undergoing stress echocardiography.

Adult↗

PubMed1996

Hemodynamics in white coat hypertension compared to ambulatory hypertension and normotension.

Hemodynamic alterations associated with the blood pressure response in subjects with white coat hypertension may provide insight into the pathophysiologic mechanisms of this condition. Systemic arterial hemodynamics were investigated with a recently validated method based on noninvasive estimates of aortic root pressure and flow in 28 subjects with white coat hypertension (diastolic pressure > or = 90 mm Hg measured by the general practitioner [GP arterial pressure] and ambulatory daytime pressures < 140/90 mm Hg), in 23 subjects with previously untreated, ambulatory hypertension (GP diastolic pressure > or = 90 and < 115 mm Hg and ambulatory daytime diastolic pressure > or = 90 mm Hg), and in 32 normotensive subjects. The groups did not differ significantly concerning age, gender, body surface area, heart rate, stroke index and cardiac index, but total peripheral resistance index was increased and total arterial compliance reduced in the white coat group and the hypertensive group compared to the normotensive group. The subjects in the white coat group with a systolic arterial pressure during echocardiography that was > 5 mm Hg higher than the ambulatory daytime systolic pressure (n = 19) had increased cardiac index, increased total peripheral resistance, and decreased total arterial compliance compared to the normotensive group. The subjects in this group with a hemodynamic pattern characterized by a high ratio of cardiac index/peripheral vascular resistance were significantly younger than the subjects with the opposite pattern. Thus, the blood pressure increase in subjects with white coat hypertension is associated with increased cardiac output, increased peripheral vascular resistance, and reduced total arterial compliance, but the hemodynamic pattern may be influenced by age.

Adult↗

PubMed1996

The importance of transesophageal echocardiography during surgery of the thoracic aorta.

OBJECTIVES: To assess left ventricular dimensions and cardiac output during thoracic and thoracoabdominal aortic aneurysm repair. MATERIAL AND METHODS: Nine patients undergoing thoracic and thoracoabdominal aneurysm repair using direct cross-clamping without shunt or by-pass were studied prospectively. Prior to, during cross-clamping (XC) and after declamping left ventricular cross-sectional areas were monitored with transesophageal echocardiography. A pulmonary artery catheter was used for measurements of cardiac output with the thermodilution technique. RESULTS: Cardiac output increased 43% from baseline during XC (p < 0.01) and was still 55% above baseline at declamping (p < 0.05). Left ventricular end-systolic inner area was reduced 32% during XC (p < 0.01). Pulmonary artery pressures and central venous pressure increased during declamping (p < 0.05). Heart rate increased 38% from 66 beats/ min to 92 beats/min (p < 0.01) and was still 30% elevated at declamping (p < 0.01). CONCLUSION: During thoracic aortic XC, cardiac output is increased and left ventricular end-systolic dimension is reduced. TEE is a valuable supplement to pressure measurements for the evaluation of cardiac function during surgery of the thoracic aorta.

Aged↗

PubMed1996

Hyperlipidaemia in renal transplant patients.

OBJECTIVES: The aim of study was to assess the prevalence and severity of hyperlipidaemia in renal transplant patients in a Nordic country. DESIGN: Multicentre, cross-sectional study. SETTING: Outpatients and ward inpatients registered from 23 hospitals covering all regions of the country. SUBJECTS: Renal transplant patients with a functioning graft were registered: 406 patients in all; that is, 43% of the national renal transplant population. All patients used prednisolone, 71% used cyclosporine, either with (51%) or without (20%) azathioprine. Total cholesterol values from general population were obtained from a national survey. MAIN OUTCOME MEASURES: Blood lipids and their relation to clinical parameters. RESULTS: Total cholesterol was significantly higher in transplant patients than in the general population for both genders and all age groups (P < 0.01). Female patients had higher total cholesterol (mean +/- SD: 7.49 +/- 1.61 mmol L(-1)) than males (7.01 +/- 1.55 mmol L(-1); P < 0.001), and also higher HDL cholesterol (1.55 +/- 0.43 vs. males: 1.32 +/- 0.46 mmol L(-1); P < 0.001). Triglycerides were equally elevated in both genders, and 33% had values above 2.2 mmol L(-1). Reduced creatinine clearance, a high body-mass index, female gender, hypertension, and coronary artery disease were independently associated with higher total cholesterol. Beta blockers were associated with lower HDL cholesterol and higher triglycerides, and diuretics with higher triglycerides. Blood lipid levels were not associated with cyclosporine immunosuppression. CONCLUSION: Hyperlipidaemia is prevalent after renal transplantation, and is associated with impaired graft function, hypertension, and with the use of beta blockers and diuretics, but not with the use of cyclosporine.

Adrenergic beta-Antagonists↗

PubMed1996

Effect of sodium nitroprusside on cerebral haemodynamics during cross-clamping of the descending thoracic aorta in pigs.

OBJECTIVE: To assess the effect of sodium nitroprusside on cerebral haemodynamics during cross-clamping of the descending thoracic aorta in pigs. DESIGN: Non-randomised controlled animal study. SETTING: University hospital, Norway. MATERIAL: 17 Pigs. INTERVENTIONS: Cross-clamping of the descending thoracic aorta for 30 minutes. In 8 pigs sodium nitroprusside was given to prevent proximal hypertension (sodium nitroprusside group); 9 pigs were given no sodium nitroprusside (control group). MAIN OUTCOME MEASURES: Intracerebral pressure, sagittal sinus pressure, cerebral flux, and internal carotid artery blood flow. RESULTS: Intracerebral pressure, sagittal sinus pressure, and cerebral flux increased in both groups during cross-clamping of the descending thoracic aorta. There were no differences between the groups in these variables despite significantly lower mean proximal aortic pressure in the sodium nitroprusside group. CONCLUSIONS: Sodium nitroprusside did not affect intracerebral pressure, sagittal sinus pressure, or cerebral flux during cross-clamping of the descending thoracic aorta. Increased cerebral blood flow rather than venous congestion is the most likely cause of increased intracranial pressure during cross-clamping of the descending thoracic aorta.

Animals↗

PubMed1996

Evaluation of reference systems for quantitative wall motion analysis from three-dimensional endocardial surface reconstruction: an echocardiographic study in subjects with and without myocardial infarction.

Six relevant computer-implemented reference systems for three-dimensional quantitative assessment of left ventricular wall motion abnormalities were compared with visual wall motion analysis of two-dimensional images. Endocardial borders were traced in three apical echocardiographic views at end-diastole and end-systole in 10 patients with myocardial infarction and 5 healthy subjects, and three-dimensional reconstruction of endocardial surfaces was performed. End-diastolic and end-systolic surfaces were aligned in a common axis system depending on the reference system, and systolic wall motion was assessed at 1,024 points on the endocardial surface. The localization of abnormal wall motion was displayed in bull's-eye maps, and the area was determined as a percentage of total endocardial area. For each reference system, the segmental concordance between three-dimensional computerized and visual assessment was determined. The best agreement between computerized and visual analysis was obtained with a reference system based on wall motion towards the major ventricular axis, whereas the poorest result was obtained using the center of left ventricular cavity as reference. Correlation between the estimated area of wall motion abnormality and visually determined wall motion score index was best using the aligned center of mitral valve plane as reference (r = .92).

Adult↗