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Biomedical subjects

T Skjaerpe

Publications and source records attributed to T Skjaerpe.

At least 37 records · Page 2Linked to original sources
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↗
PubMed1994

Iodixanol in cardioangiography. A double-blind parallel comparison between iodixanol 320 mg I/ml and ioxaglate 320 mg I/ml.

Iodixanol (Visipaque) 320 mg I/ml, a non-ionic, dimeric, isotonic contrast medium, was compared to ioxaglate (Hexabrix) 320 mg I/ml in cardioangiography. One hundred and two patients with normal renal function were included in the study. The objectives were to evaluate safety, tolerability, radiographic efficacy and effects on renal function. Adverse events, discomfort, vital signs, clinical chemistry parameters, diagnostic information and radiographic density were recorded. Both contrast media had minor effects on the renal function parameters monitored. The patients who received iodixanol experienced fewer adverse events, significantly less discomfort and had a lower increase in heart rate than did the patients in the ioxaglate group. The radiographic efficacy was good in both groups. Iodixanol 320 mg I/ml is safe and effective for use in cardioangiography.

Adult↗
PubMed1993

Digital dipyridamole stress echocardiography in silent ischemia after coronary artery bypass grafting and/or after healing of acute myocardial infarction.

This study evaluates dipyridamole stress echocardiography in silent ischemia. Fourteen patients with previous coronary artery bypass grafting (group A) and 16 patients with healed myocardial infarction (group B) were studied. All had > or = 1 mm ST depression without chest pain during bicycle exercise testing. Left ventricular wall motion was analyzed using a computerized display of digital systolic cineloops with a high frame rate. Test results were compared with coronary angiography. Dipyridamole echocardiography accurately identified patients with significant coronary artery stenosis in both groups (3 of 4 in group A, 11 of 14 in group B). Retrograde flow to the occluded native artery was associated with positive results on dipyridamole testing in 6 of 7 patients in group A and all 3 in group B. Sensitivity, specificity and diagnostic accuracy for detecting significant coronary stenosis or occlusions with retrograde flow was 78, 100 and 83%, respectively. Patients with angiographic multivessel disease had a significantly larger increase in wall motion score index during dipyridamole stress than patients with 0- or 1-vessel disease, 0.18 +/- 0.11 versus 0.05 +/- 0.18 (p < 0.05). Two patients developed symptomatic bradycardia and hypotension during dipyridamole infusion. It is concluded that dipyridamole echocardiography accurately identifies myocardial regions with restricted coronary flow. Stress echocardiography is a valuable tool for assessing coronary flow in silent ischemia.

Adult↗
PubMed1993

Rapid systolic intraventricular velocities after valve replacement for aortic stenosis.

To assess the frequency and severity of intraventricular gradients after valve replacement for severe valvular aortic stenosis 25 patients (valve area 0.59 +/- 0.19 cm2) were studied serially with Doppler echocardiography on postoperative days 1, 2, 3, 5 and 7. Pulsed Doppler was used to search for increased intraventricular velocities. Mid-to-late systolic intraventricular velocities > or = 2 m/s were defined as intraventricular gradients. In 13 patients (52%) intraventricular gradients were found at least once during days 1 to 7 (group A) and were most frequent at day 3 (44%). The typical location of these velocities was at the midventricular level close to the septum. In 4 patients intraventricular gradients > 64 mm Hg were found. Left ventricular end-diastolic and end-systolic diameters recorded preoperatively were significantly smaller in group A than in the rest (43.6 +/- 5.4 vs 50 +/- 5.8 mm and 24.6 +/- 5.6 vs 33.1 +/- 7.3 mm, both p < 0.05) and the fractional shortening was significantly higher (44 +/- 9 vs 34 +/- 9%, p < 0.05). It is concluded that intraventricular gradients are frequent during the first week after valve replacement for severe aortic stenosis. These gradients are mostly mild and transient in nature, but significant gradients associated with clinical deterioration may occur. The risk of developing intraventricular gradients postoperatively may be predicted at a preoperative echocardiographic examination, and patients with a small left ventricular cavity size and maintained contractility are at particular risk.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Exercise hemodynamics in small (< or = 21 mm) aortic valve prostheses assessed by Doppler echocardiography.

Exercise Doppler echocardiography was used to assess hemodynamics in 25 patients with a < or = 21 mm aortic valve prosthesis (14 with a Medtronic-Hall 21 mm valve, three with a Medtronic-Hall 20 mm valve, three with a Sorin 21 mm valve, one with a Duromedics 21 mm valve, and four with a Carpentier-Edwards 21 mm valve). A symptom-limited upright bicycle exercise test was performed, and Doppler gradients were recorded during exercise. Gradients increased with exercise from 30 +/- 8/16 +/- 4 mm Hg (peak/mean) at rest to 46 +/- 12/24 +/- 7 mm Hg during exercise; both p < 0.001. Mean exercise gradient exceeded 30 mm Hg in five patients, and the highest mean gradient recorded was 37 mm Hg. Within the group of mechanical valves, gradients at exercise were similar for different types of valves. A linear relationship was found between gradients at rest and during exercise (peak r = 0.75, mean r = 0.77; both p < 0.001). Additional findings were midventricular velocities exceeding 1.5 m/sec in late systole in 10 patients (40%) and intraventricular flow (> or = 0.2 m/sec) toward the apex during isovolumic relaxation in 11 patients (44%). The patients with these velocity patterns had significantly smaller left ventricular cavities (end-diastolic diameter 39.8 +/- 4.8 vs 46.5 +/- 4.2 mm, p < 0.01; end-systolic diameter 24.2 +/- 3.0 vs 28.5 +/- 4.5 mm, p = 0.013).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Two-dimensional echocardiography for prediction of aortic valve prosthesis size. A comparative study of Medtronic-Hall and Carpentier-Edwards supra-annular valves.

To assess the value of two-dimensional echocardiography (2D ECHO) for predicting prosthetic aortic valve size, the diameter of the aortic annulus was measured before implantation of a Medtronic-Hall valve in 24 patients and a Carpentier-Edwards supra-annular valve in 34. In the Medtronic-Hall group, the average prosthesis size was similar to the average annulus diameter, i.e. 23.2 +/- 2.1 vs 23.0 +/- 3.4 mm (NS), 95% confidence interval for the difference -1.0-0.7 mm. In the Carpentier-Edwards group the corresponding figures were 23.5 +/- 2.1 and 22.0 +/- 2.3 mm (p < 0.001), with 95% confidence interval 0.9-2.0 mm. Correlation between annulus diameter indicated by preoperative 2D ECHO and prosthesis size was stronger in the Medtronic-Hall (r = 0.88, p < 0.001) than in the Carpentier-Edwards group (r = 0.73, p < 0.001). The authors conclude that prosthetic aortic valve size may be accurately predicted by 2D ECHO, with Medtronic-Hall valve size similar to, and Carpentier-Edwards prostheses on average 1-2 mm larger than the 2D ECHO-estimated annulus diameter.

Adult↗
PubMed1992

Hemodynamic evaluation by Doppler echocardiography of small (less than or equal to 21 mm) prostheses and bioprostheses in the aortic valve position.

To assess resting hemodynamics of an unselected group of patients with prostheses or bioprostheses sized less than or equal to 21 mm implanted into the aortic valve position during a 7-year period, 46 of 50 eligible patients were examined by Doppler echocardiography. The valves were Carpentier-Edwards (CE) supraannular 21 mm (n = 8), Medtronic-Hall (MH) 20 mm (n = 8) and 21 mm (n = 21), and the rest (n = 9) were other valves with only 1 to 3 patients in each group. Gradients, valve areas and dimensionless obstruction indexes (ratio of subvalvular/valvular velocities and velocity time integrals) were compared. By analysis of variance, gradients did not differ significantly between the CE supraannular 21 mm, the MH 20 and 21 mm prostheses (peak/mean 25 +/- 8/14 +/- 5, 31 +/- 13/16 +/- 6 and 25 +/- 10/13 +/- 5 mm Hg; p = not significant). Only 2 patients had a mean gradient greater than 25 mm Hg. The valve area was slightly larger for the MH 21 mm group compared with the CE supraannular 21 mm group (1.34 +/- 0.15 vs 1.16 +/- 0.14 cm2, p less than 0.05). The dimensionless obstruction indexes did not differ (CE supraannular 21 mm 0.36 +/- 0.07/0.40 +/- 0.07 (velocities/velocity time integrals), MH 20 mm 0.40 +/- 0.12/0.47 +/- 0.12, MH 21 mm 0.38 +/- 0.05/0.44 +/- 0.06; p = not significant).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Impact of changes in heart rate and stroke volume on the cross sectional flow velocity distribution of diastolic mitral blood flow. A study on 6 patients with pacemakers programmed at different heart rates.

The effect of changes in stroke volume on the cross sectional velocity distribution in the mitral orifice during passive mitral inflow was studied in six patients with total atrioventricular block, atrial fibrillation and VVI pacemakers during periods with different heart rates. The time velocity integrals recorded both in the left ventricular outflow tract and at the mitral orifice decreased significantly as the heart rate was increased from 60 to 80 and from 80 to 100 beats per minute. Instantaneous cross sectional flow velocity profiles were constructed by time interpolation of the velocity data from each point in sequentially delayed two dimensional digital ultrasound maps. Each patient had a characteristic cross sectional flow velocity profile in the mitral orifice recorded at the level of the leaflet tips in a four chamber view. The velocity profiles varied between the patients. With increase in heart rate only minimal changes in the flow profiles from individual patients were seen. The maximum velocity through the mitral orifice overestimated the cross sectional mean velocity at the same time by a factor of 1.4-1.9. The maximum time velocity integral overestimated the cross sectional mean by a factor of 1.4-1.8. The observed cross sectional skew varied between patients but did not change significantly with increasing heart rate and decrease in stroke volume.

Aged↗
PubMed1992

Cross-sectional early mitral flow-velocity profiles from color Doppler in patients with mitral valve disease.

BACKGROUND: Cross-sectional flow-velocity profiles from early mitral flow in 20 patients (10 with mitral regurgitation and 10 with mitral stenosis) were constructed from the velocity data from each point in sequentially delayed two-dimensional digital Doppler ultrasound maps. METHODS AND RESULTS: The data suggested that the early mitral flow studied in an apical four-chamber view was variably skewed in both patient groups. The maximum flow velocity overestimated the cross-sectional mean velocity at the same time by a factor of 1.12-1.86. The maximum time-velocity integral was 1.13-1.77-fold greater than the cross-sectional mean time-velocity integral. In patients with mitral regurgitation, the cross-sectional flow-velocity profile appeared to be most skewed at the level of the mitral leaflet tips. The level of the mitral annulus appeared to give the most homogenous flow-velocity distribution in both patient groups. CONCLUSIONS: When calculations of volume flow are based on pulsed Doppler ultrasound recordings with a single sample volume, the possibility of a skewed flow-velocity profile must be taken into account.

Adult↗
PubMed1991

Validity of an early postoperative baseline Doppler recording after aortic valve replacement.

In 131 patients undergoing aortic valve replacement (53 bioprostheses, 78 mechanical), the pressure decrease across the prosthesis was recorded with Doppler ultrasound at a baseline study early postoperatively (mean 11 +/- 5 days) and compared with a repeat measurement 3 to 5 months later. At baseline the hemodynamic state was markedly different, with increased heart rate (89 +/- 14 vs. 74 +/- 13 beats/min, p less than 0.001) and decreased left ventricular ejection time index (367 +/- 21 vs 390 +/- 22, p less than 0.001). A minor and clinically insignificant decrease in pressure decrease with time was found. The 95% confidence interval for the difference was 0.2 to 3.0 and 0.2 to 1.7 mm Hg for the peak and the mean pressure decrease, respectively. The change in pressure decrease was statistically significant for bioprostheses (mean 16 +/- 5 vs 14 +/- 4 mm Hg, p less than 0.01) and smaller (less than or equal to 23 mm) valves (mean 17 +/- 4 vs 15 +/- 4 mm Hg, p less than 0.01), whereas no significant changes were found for mechanical valves or valves of a larger size. The change in mean pressure decrease from baseline to the second examination was within +/- 5 mm Hg for 82% of patients. It is concluded that despite a different hemodynamic state in the early postoperative period, the pressure decrease across aortic valve prostheses obtained at this time can be used as a reference for later comparison.

Aortic Valve↗
PubMed1989

Half time of the diastolic aortoventricular pressure difference by continuous wave Doppler ultrasound: a measure of the severity of aortic regurgitation?

Thirty four patients with aortic regurgitation were studied by continuous wave Doppler ultrasound. In 30 of these the regurgitation was graded by cineangiography as mild, moderate, or severe and in four severe regurgitation was confirmed at operation. The half times of the aortoventricular pressure differences obtained with Doppler compared well with those obtained from pressure recordings at catheterisation. The relation between pressure half times and cineangiographic gradings of severity was not consistent. Similarly, a control group of patients without aortic regurgitation showed a wide range of the invasively recorded pressure half times which overlapped with those in patients with aortic regurgitation. This suggests that factors such as systemic vascular resistance, and aortic and left ventricular compliance can have an appreciable effect on the pressure half time. If these factors are not included the method will be of limited value, except in patients with pressure half times of less than 300 ms, when regurgitation invariably is severe. These results suggest that at present the method is of value only in recognising the patients with the most severe aortic regurgitation who need early operation.

Adult↗
PubMed1989

Cross sectional early mitral flow velocity profiles from colour Doppler.

Instantaneous cross sectional flow velocity profiles from early mitral flow in 10 healthy men were constructed by time interpolation of the velocity data from each point in sequentially delayed two dimensional digital Doppler ultrasound maps. This interpolation allows correction of the artificially produced skewness of velocities across the flow sector caused by the time taken to scan the flow sector for velocity recording of pulsatile blood flow. These results suggested that early mitral flow studied in an apical four chamber view is variably skewed both at the leaflet tips and at the annulus. The maximum flow velocity overestimated the cross sectional mean velocity at the same time by a factor of 1.2-2.2. Also the maximum time velocity integral overestimated the cross sectional mean time velocity integral to the same extent. This cross sectional skew must be taken into account when calculation of blood flow is based on recordings with pulsed wave Doppler ultrasound from a single sample volume.

Adolescent↗
PubMed1986

Noninvasive estimation of systolic pressure in the right ventricle in patients with tricuspid regurgitation.

In 70 patients, tricuspid regurgitation was diagnosed with Doppler by recording reverse flow in systole originating at the tricuspid orifice, directed into the right atrium. The peak velocities were recorded, and the peak pressure drop from the right ventricle to the right atrium in systole was calculated from the simplified Bernoulli equation (pressure drop = 4 X 4 X Vmax2), and was found to correlate well with invasive measurements (r = 0.97, SEE +/- 6.1 mmHg). Central venous pressure was judged by neck vein congestion and added to the pressure drop to obtain a noninvasive estimation of systolic right ventricular pressure. Correlation with catheterization measurements was good (r = 0.96, SEE +/- 7.1 mmHg). In patients in whom the tricuspid regurgitation was judged as mild with Doppler, the correlation between noninvasive and invasive measurements of the transtricuspid pressure drop was still good (r = 0.95, SEE +/- 5.1 mmHg), indicating that the viscosity of the blood does not invalidate the use of the simplified Bernoulli equation when the regurgitant area of the valve is small.

Adolescent↗
PubMed1985

Diagnosis of tricuspid regurgitation. Sensitivity of Doppler ultrasound compared with contrast echocardiography.

Fifty-one patients underwent Doppler studies of tricuspid flow and 2-D derived M-mode studies of the inferior vena cava (IVC) during upper extremity contrast injections. Tricuspid regurgitation (TR) was diagnosed with Doppler when reverse flow in systole was recorded at and behind the closure level of the tricuspid valve. TR was diagnosed with contrast echocardiography (CE) when contrast appeared in the IVC between the onset of the QRS complex and the end of the T-wave of the ECG. Of the 49 patients who had TR diagnosed with Doppler, contrast was recorded in the IVC in 46, but only 18 (37%) fulfilled the criterion for a positive CE study. When the severity of the TR was semiquantitated with Doppler, CE diagnosed 1 of 25 mild, 5 of 11 moderate, and 12 of 13 severe regurgitations. When systolic contrast appearance in the IVC after the peak of the R-wave was used as the criterion for a positive contrast study, CE missed 2 of 13 severe regurgitations. In the 24 catheterized patients the CE study was positive only when an abnormal V-wave in the right atrial pressure curve was present. Doppler is a more sensitive method than CE for diagnosing TR and is more readily applied.

Adult↗
PubMed1985

Noninvasive estimation of valve area in patients with aortic stenosis by Doppler ultrasound and two-dimensional echocardiography.

In 30 patients with aortic stenosis, 14 of whom also had significant aortic regurgitation, the velocities in the stenotic jet (V') and below the valve (V) were recorded by Doppler ultrasound. With two-dimensional echocardiography, two subvalvular areas (A) were calculated from leading-to-leading edge ("large") and trailing-to-leading edge ("inner") diameter measurements. The aortic valve area was calculated by the equation of continuity (A' = A X peak V/peak V') and by calculating stroke volume below the valve [A X integral of V (t) and dividing by the integral of V' (t) (= A"). Based on cardiac output estimations from single-plane angiographic images, Gorlin's formula was used to calculate invasive valve areas. In patients with no or mild aortic regurgitation a second invasive estimate was based on cardiac output measured by the Fick method. The best correlation was found when A' (with "large" diameter) was compared with invasive results based on cardiac output measured by the Fick method (r = .89, SEE +/- 0.12, n = 16); the worst was found when A" (with "large" diameter) was compared with invasive results based on cardiac output measurements by single-plane angiography (r = .80, SEE +/- 0.20, n = 30). The results indicate that valve area in patients with aortic stenosis can be reliably estimated noninvasively, even in those with significant aortic regurgitation.

Aortic Valve↗
PubMedDate not supplied

Cross-sectional left ventricular outflow tract velocities before and after aortic valve replacement: a comparative study with two-dimensional Doppler ultrasound.

To assess whether aortic valve replacement (AVR) results in changes in the flow velocity distribution in the left ventricular outflow tract (LVOT), 10 patients undergoing AVR for aortic stenosis were studied. By extracting velocity information from color flow maps as digital data, instantaneous cross-sectional velocity profiles were constructed. Velocity profiles obtained 1 to 3 days before AVR were compared with recordings made 3 months later. The LVOT velocity profiles were variably skewed both before and after surgery, and no systematic or uniform changes could be detected after AVR. The highest velocities were most often localized in the region from the center of the outflow tract diameter toward the septum both before and after surgery. At the time of peak flow the ratio of the maximum to the cross-sectional mean velocity was 1.38 +/- 0.13 before and 1.39 +/- 0.08 after AVR (NS), and the ratio of the maximum to the mean velocity time integral was 1.47 +/- 0.10 before and 1.56 +/- 0.10 after (NS). We conclude that AVR in patients with aortic stenosis does not result in a change in LVOT velocity profiles that will influence stroke volume estimates with the Doppler technique.

Aged↗
PubMedDate not supplied

Thrombotic disc impediment in a Medtronic-Hall aortic valve prosthesis diagnosed by Doppler echocardiography followed by successful reoperation.

A case with impeded disc movement caused by thrombus formation in a Medtronic-Hall aortic valve prosthesis is reported. A correct diagnosis, including both mechanism and severity of the prosthesis failure, was established by Doppler echocardiography. The patient was promptly referred for surgery without invasive or other supplementary investigations.

Aortic Valve↗