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Biomedical subjects

W Voelker

Publications and source records attributed to W Voelker.

At least 91 records · Page 5Linked to original sources
PubMed1989

Myocardial properties of the new dihydropyridine calcium antagonist isradipine compared to nifedipine with or without additional beta blockade in coronary artery disease.

Isradipine is a new dihydropyridine calcium antagonist with myocardial effects significantly different from those of nifedipine, as shown by in vitro and animal experimental data. Isradipine selectively inhibits the sinus node but not the atrioventricular conduction and its negative inotropic action is much less if administered in a dose of comparable peripheral effects. To study these effects in man, 40 patients with coronary artery disease were divided into 2 groups receiving either a continuous 30-minute intravenous infusion of 2 mg of nifedipine or 0.5 mg of isradipine, doses that resulted in a comparable afterload reduction (decrease of systemic vascular resistance: nifedipine -22.1%, isradipine -25%, p less than 0.001). Ten patients in each group received an additional intravenous bolus of 5 mg of propranolol at the end of the calcium antagonist administration to antagonize its induced adrenergic reflex mechanisms. The heart rate significantly increased after nifedipine only (+9.2%, p less than 0.001), experienced no change after isradipine and the nifedipine and propranolol combination and decreased after the combination of isradipine and propranolol (-9.6%, p less than 0.001). This resulted in a significant decrease of the rate pressure product with isradipine (-12.5%, p less than 0.001) but not with nifedipine. As a result of the afterload-induced adrenergic reflex mechanisms, the maximal derivative of the left ventricular pressure increased after isradipine administration (+13.5%, p less than 0.001) and was unchanged after nifedipine, which demonstrates the significantly less negative inotropic properties of isradipine as compared with nifedipine.

Adrenergic beta-Antagonists↗
PubMed1989

Quantification of myocardial ischemia and infarction with single photon emission computed tomography.

To evaluate the feasibility of 201Tl single photon emission computed tomography (SPECT) for quantitative detection of myocardial infarction and ischemia, scintigraphic studies were related to angiographic findings. In study A infarct sizes with SPECT were compared with the angiographic infarct sizes of 30 patients. A linear correlation was found for the % infarct of the left ventricular circumference between both methods (r = 0.73; P less than 0.001; mean infarct size 20.7% +/- 10.5% (angio) vs 19.8% +/- 12.9% (SPECT), mean +/- SD). Furthermore, a significant inverse correlation between scintigraphic infarct size and left ventricular ejection fraction (r = -0.87, P less than 0.001) was obtained. In study B exercise/rest 201Tl SPECT was used for quantification of myocardial ischemia. Forty-three patients underwent both stress 201Tl SPECT and biplane exercise left ventriculography. Ischemia was expressed as % defect size of the left ventricular circumference. Sensitivity and specificity for detection of ischemia were 96% and 100% respectively with stress SPECT. Extent of myocardial ischemia correlated significantly with both methods (r = 0.63; SPECT defect = 1.0 angiographic ischemia +2%; P less than 0.001). The regression followed the line of identity and the mean sizes of ischemia were identical (SPECT 12.2 +/- 7.6% vs 14.6 +/- 12.4% ventriculography, mean +/- SD) demonstrating the agreement of both methods. However, there was some intraindividual variance between the scintigraphic and the angiographic study. The sensitivity and specificity in single regions with SPECT were lower compared to the global test results.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiography↗
PubMed1989

Myocardial bridges at multiple sites over the left coronary artery in a patient with hypertrophic cardiomyopathy.

In a 47-year-old male with hypertrophic cardiomyopathy, coronary angiography revealed three myocardial bridges associated with significant systolic narrowing of the left coronary artery. Measurements during pacing and exercise demonstrated no sign of myocardial ischemia. Ten-year follow-up was uneventful. Thus, the prognosis of myocardial bridges, even when located at multiple sites across the left coronary artery, seems benign.

Angiography↗
PubMed1989

Validation of continuous-wave Doppler measurements of mitral valve gradients during exercise--a simultaneous Doppler-catheter study.

In patients with mitral stenosis, continuous-wave Doppler measurements of the maximal transmitral inflow velocity can be converted into transvalvular pressure gradients using the modified Bernoulli equation. Because of close correlations between Doppler- and catheter-measured gradients this method has become a valuable tool in non-invasive evaluation of mitral stenosis at rest. However, in some patients, exercise studies are necessary to determine the haemodynamic significance of the valve stenosis. The accuracy of continuous-wave Doppler in this setting has not yet been validated. Thus, in 20 selected patients with pure or predominant mitral stenosis, continuous-wave Doppler echocardiography was performed during left- and right-heart catheterization. At rest and during submaximal bicycle exercise, Doppler and pressure measurements were simultaneously performed. The Doppler gradient was calculated according to the modified Bernoulli equation while the mean manometric gradient was determined from the simultaneous pulmonary wedge and left ventricular pressure curves. Exercise caused a significant increase of cardiac output (4.8 +/- 1.3 to 5.7 +/- 1.31 min-1) and heart rate (59.7 +/- 12.0 to 95.3 +/- 14.3 beats min-1). The mean Doppler gradient increased from 6.8 +/- 2.1 to 12.2 +/- 3.2 mmHg. The manometric gradient showed a comparable increase of 9.5 +/- 2.4 to 17.2 +/- 3.7 mmHg, respectively. Correlation between Doppler and manometric data was close (y = 0.79x-0.67,r = 0.90,SEE = 0.97 mmHg) at rest and still good during exercise (y = 0.71x-0.10,r = 0.82,SEE = 1.97 mmHg). Thus, in some patients with borderline resting gradients and valve areas, exercise Doppler might allow further identification of the haemodynamic severity of mitral stenosis.

Adult↗
PubMed1989

[Success and complication rates of coronary angioplasty in the unstable angina pectoris stage after myocardial infarct--a comparison with percutaneous transluminal coronary angioplasty in the acute infarct stage and unstable angina pectoris without preceding myocardial infarct].

To evaluate whether there is a difference in terms of the success and complication rates of PTCA in patients (pts) with unstable angina pectoris (UAP) after myocardial infarction (group I) and patients with myocardial infarction (group II), as well as in patients with UAP without preceding myocardial infarction (group III), we analyzed the data of 188 patients retrospectively. Acute PTCA was performed in 42 patients of group I, 55 patients of group II, and 91 patients of group III. The primary success rate was comparable in all three groups (group I: 74%; group II: 76%; group III: 77%). The incidence of acute ACVB operation was comparable in group I (5 pts: 9%) and group III (10 pts: 11%). One patient was operated during an acute myocardial infarction. Five patients of group I (9%) and seven patients of group III (8%) developed a myocardial infarction. Three patients of group I (7%) and three patients of group II (5%) died during hospitalization. PTCA performed during acute myocardial ischemia has the highest complication rate in patients with UAP after myocardial infarction and is considerably higher than in patients with UAP without preceding infarction.

Angina Pectoris↗
PubMed1989

[The acute hemodynamic effects of the new vasodilating beta blocker carvedilol in comparison with combined administration of nifedipine and propranolol in patients with coronary heart disease].

The acute hemodynamic effects of carvedilol, a new vasodilating betablocker, were assessed in comparison to the response to nifedipine or a combination of nifedipine and propranolol in patients with coronary artery disease. Either 5 mg carvedilol, 2 mg nifedipine or 2 mg nifedipine + 5 mg propranolol (N + P) were administered intravenously in a not randomized study within 30 min to 10 patients for each drug. Carvedilol reduced (comparable to the effect of N + P) the left ventricular afterload with a decrease of AOPm of 12.6%, p less than 0.001 (N + P -11.8%, p less than 0.001) and systemic vascular resistance of 9.1%, p less than 0.02 (N + P -10.0%, p less than 0.01) and no change of cardiac index. Single treatment with nifedipine leads to a reflex increase of heart rate which could not be observed after carvedilol or N + P as a result of the betablocking properties of carvedilol and propranolol. Therefore, the rate-pressure-product at rest was unchanged after nifedipine but decreased significantly after carvedilol (-10.9%, p less than 0.01) and N + P (-12.4%, p less than 0.01). Negative inotropic effects were significantly lower after carvedilol, with a 6.3% (p less than 0.05) decrease of LV dP/dtmax, compared to N + P (-12.0%, p less than 0.01). Since preload, afterload, and heart rate changes were equal in both groups negative inotropic effects can be compared on the base of dP/dtmax changes. The acute hemodynamic effects (vasodilation without reflex tachycardia, negative inotropic effects) of the new vasodilating betablocker carvedilol are comparable to a combined treatment with nifedipine and propranolol in patients with coronary artery disease and well preserved left ventricular global function.

Carbazoles↗
PubMed1989

[Doppler echocardiography measurement of the regurgitation fraction in patients with aortic valve insufficiency].

The purpose of this study was to assess the clinical utility of pulsed Doppler echocardiography in the determination of regurgitant fraction in patients with aortic regurgitation. Therefore, in 33 unselected consecutive patients with aortic regurgitation, and in 16 patients without heart disease Doppler echocardiography was performed to measure blood flow at the aortic and pulmonary valve. The regurgitant blood flow (RBV) was calculated as the difference of the stroke volumes measured at the aortic and pulmonary valve. The regurgitant fraction (RF) was computed as RBV/aortic flow. At cardiac catheterization RBV and RF were calculated from the left ventricular angiographic stroke volume and the stroke volume measured by thermodilution technique. Four patients were excluded because of technically poor left-ventricular angiograms. In eight patients with aortic regurgitation Doppler measurement of RBV and RF was impossible. The correlations between the invasive and the Doppler data were significant in 21 patients with aortic regurgitation (RBV: r = 0.87, SEE = 16.1 ml; RF: r = 0.90, SEE = 8.1%). However, the RF (41.6 +/- 17.6%) was overestimated by Doppler echocardiography (46.0 +/- 17.9%; p les than 0.021). In the control group RBV ranged between -8.1 ml and 10.5 ml and RF between -13.3% and 7.4%. Thus, pulsed Doppler echocardiography is clinically useful in determination of the regurgitant fraction in about 70% of patients with pure aortic regurgitation. The Doppler method, however, is limited in the diagnosis and quantification of mild aortic regurgitation.

Adolescent↗
PubMed1989

[Determination of the right ventricular ejection fraction from the exponential decrease in the thermodilution curve--a comparison with biplanar cineventriculography].

Using the exponential downslope of the thermodilution curve right ventricular ejection fraction and volumes can be calculated. To evaluate the accuracy of this method for clinical application thermodilution measurements were compared to the results of biplane cineventriculography in 40 patients. Mean right ventricular ejection fraction was 52 +/- 9% determined by thermodilution (Th), and 53 +/- 8% determined by angiography (A). Mean enddiastolic volume was 189 +/- 74 ml (Th) and 162 +/- 42 ml (A) and mean endsystolic volume 92 +/- 42 ml (Th) and 75 +/- 20 ml (A). Ejection fraction of thermodilution measurements correlated with the results of angiography (r = 0.59; SEE = 7%; % SEE = 13 rel. %; p less than 0.001). The correlation for endsystolic volume was: r = 0.50; SEE = 36 ml; % SEE = 48%; p less than 0.001, and for enddiastolic volume: r = 0.36; SEE = 70 ml; % SEE = 43%; p less than 0.05. The differences in ejection fraction calculated by the two different methods were especially high (up to 25%) in patients (n = 10) with low (less than 110 ml) or high (greater than or equal to 200 ml) enddiastolic volume. For the other 30 patients the correlation for right ventricular ejection fraction was: r = 0.82; SEE = 5%; % SEE = 9 rel. %; p less than 0.001. Thus, the thermodilution method allows an approximative assessment of right ventricular ejection fraction only in patients with a normal right ventricle. Since right ventricular ejection fraction cannot be determined with sufficient accuracy in patients with right ventricular dilatation, the clinical application of this method is limited.

Cardiac Output↗
PubMed1988

[Value of 2-D echocardiography in the detection of stress-induced wall-motion abnormalities in coronary heart disease--a comparison with biplane cineventriculography].

To determine the accuracy of echocardiography in assessment of exercise-induced wall motion abnormalities, the results of stress-echocardiography were compared with exercise-cineventriculography. In 56 consecutive patients biplane cineventriculography at rest and immediately after supine bicycle exercise was performed. Cross-sectional echocardiography was obtained using the apical 2- and 4-chamber view for LV imaging under identical exercise conditions. In 6 of the 56 patients 2-D echo, in 8 patients LV-angio, and in 2 patients both methods were of inadequate quality during exercise. Thus, in 40 patients (34 patients had coronary artery disease) local wall motion of 360 wall segments was analysed. 49 segments (14%) of 24 patients showed exercise-induced ischemic wall motion abnormalities during cineventriculography. Only 24 of these 49 asynergics (49%) were also detected by 2-D-echo. Using cross-sectional echocardiography, ischemia related wall motion abnormalities were best detected laterally and septaly, whereas apical asynergies were identified in 3 of 12 segments only. Thus, the clinical value of exercise 2-D echo as a screening method in patients suspected to have coronary artery disease is limited and restricted to patients with excellent visualization of the left ventricular endocardium.

Cineangiography↗
PubMed1988

Diagnostic accuracy of 2-D echocardiography for detection of exercise-induced wall motion abnormalities in patients with coronary artery disease: comparison to biplane cineventriculography.

To determine the accuracy of two-dimensional echocardiography (2-D echo) for assessment of exercise-induced wall motion abnormalities in patients with coronary artery disease, the results of stress echocardiography were compared with exercise cineventriculography. In 56 consecutive patients, biplane cineventriculography at rest and immediately after supine bicycle exercise was performed. Cross-sectional echo was obtained using the apical two- and four-chamber-views for left ventricular imaging under identical conditions. In 6 of the 56 patients 2-D echo, in 8 patients cineventriculogram, and in 2 patients both methods were of inadequate quality at rest or during exercise. Of the remaining 40 patients, 34 had coronary artery disease. Local wall motion in 360 wall segments from these patients was analyzed. In 49 segments (14%) in 24 of these patients exercise-induced ischemic wall motion abnormalities were evident during cineventriculography. Only 24 of these 49 asynergies (49%) were also recognized by 2-D echo. Using cross-sectional echocardiography, ischemia-related wall motion abnormalities were best detected septal, whereas apical asynergies were identified in only 3 of 12 segments (25%). Thus, the clinical value of exercise 2-D echo as a screening method in patients suspected of having coronary artery disease is limited and restricted to patients where excellent visualization of the left ventricular endocardium is possible.

Cineangiography↗
PubMed1988

Determination of right ventricular ejection fraction by thermodilution technique--a comparison to biplane cineventriculography.

Determination of right ventricular ejection fraction (RVEF) provides information about global right ventricular function, which may be important for the management of patients with various heart diseases. Right ventricular ejection fraction can be determined by new thermodilution techniques using fast-response thermistors. To evaluate the validity of these methods, thermodilution measurements were compared with biplane cineventriculography in 22 patients undergoing cardiac catheterization. In all patients standard deviation of RVEF was below 5%. Mean RVEF, determined by thermodilution, was 52% +/- 9%, ranging from 32% to 71% and correlated significantly with the results of angiography (RVEF: 52% +/- 9%) (r = 0.80, SEE +/- 5%, n = 22, p less than 0.001). Correlation was good especially in patients with small right ventricles (less than 160 ml) (r = 0.91, SEE +/- 5%, n = 13, p less than 0.001), lower heart rates (less than 65/min) (r = 0.84, SEE = +/- 6%, n = 12, p less than 0.001) and cardiac output below 5.51/min (r = 0.88, SEE +/- 6%, n = 11, p less than 0.001). Thus, if valid catheter placement is possible, right ventricular ejection fraction can be determined by thermodilution technique with good reproducibility and sufficient accuracy compared to biplane angio. Validation of this method in larger patient populations with various heart diseases is necessary.

Aged↗
PubMed1988

Accuracy of Doppler echocardiography in quantification of left to right shunts in adult patients with atrial septal defect.

In previous experimental and pediatric studies, the ratio of pulmonary to systemic flow (Qp/Qs) was accurately estimated by Doppler echocardiography in various cardiac shunt lesions. The purpose of this study was to assess the accuracy of pulsed Doppler echocardiography in determining the magnitude of shunt flow in adult patients with an ostium secundum type atrial septal defect. In 32 patients with high quality echocardiograms and excellent Doppler signals, blood flow was measured in the right and left ventricular outflow tract by Doppler echocardiography. In 16 patients without heart disease, the correlation (r) between systemic (Qs) and pulmonary (Qp) blood flow was 0.96 (SEE = 0.417 liter/min, y = 1.05x - 0.21) and the mean Qp/Qs ratio was 1.01 +/- 0.09. In 16 patients with an atrial septal defect, the Qp/Qs ration measured by oximetry ranged from 1.34 to 4.61 and by pulsed Doppler echocardiography from 1.31 to 4.46 (p = NS). In these 16 patients, the correlation between the Qp/Qs ratio determined by oximetry and pulsed Doppler echocardiography was significant (r = 0.82, SEE = 0.54). In the total group of 32 patients, the correlation was stronger (r = 0.93, SEE = 0.37). Systematic differences between the invasive and noninvasive shunt calculations did not occur. Thus, in adult patients with an atrial septal defect of the secundum type and high quality echocardiograms, the magnitude of left to right shunt can be accurately assessed by pulsed Doppler echocardiography. In the absence of pulmonary hypertension, pulsed Doppler echocardiography provides precise information for the decision to undertake conservative or operative treatment.

Adult↗
PubMed1988

[Isradipine (PN 200-110), a new dihydropyridine calcium antagonist with slight negative inotropic properties in comparison with nifedipine].

The influence of isradipine (PN 200-110), a new dihydropyridine calcium antagonist, in comparison to nifedipine and placebo on hemodynamics and left ventricular function was investigated in patients with coronary artery disease (10 patients in each group). The drugs were infused intravenously within 30 min in a dosage which led to a comparable afterload reduction (nifedipine [N] 2 mg, isradipine [I] 0.5 mg, AOP mean decrease: N, 14.7%, I, 13.1%). Increase of cardiac output (N +12.5%, I +15%) and decrease of systemic vascular resistance (N -29.2%, I -25%) were equal in both groups. Nifedipine caused a significant reflex increase of heart rate (+9.2%, p less than 0.001), which was not present with isradipine. The consequence was a significant decrease of the rate-pressure product with isradipine only (-12.5%, p less than 0.001) and not with nifedipine. Although afterload reduction was equal in both groups, isradipine caused a more pronounced decrease of LV volumes (EDVI: N -10%, I -16%) and an increase of ejection fraction (N +8%, I +14%). A significant increase of dp/dtmax, as a result of the afterload reduction, occurred after isradipine only (+13.5%, p less than 0.001) with no changes of dp/dtmax after nifedipine. Since changes of parameters (preload, afterload, HR, LVSP), which influence dp/dtmax independent of the inotropic state, were equal in both groups, the increase of dp/dtmax after isradipine should be a result of less negative inotropic properties of isradipine compared to nifedipine.

Angina Pectoris↗
PubMed1988

[Post-traumatic aneurysm of the right ventricular outflow tract with concomitant tricuspid valve insufficiency].

Right ventricular aneurysms of different etiology are rare findings. Aneurysms of traumatic origin after penetrating accidents are reported. After nonpenetrating traumas formation of a right ventricular aneurysm, however, has not yet been reported. This case report deals with a 25-year-old patient who developed an aneurysm of the right ventricular outflow tract and tricuspid regurgitation after a nonpenetrating chest trauma. Clinical, hemodynamic, and echocardiographic findings with a follow up for 18 months demonstrate excellent adaptation to the traumatic changes. Therapeutic consequences are discussed with respect to the literature and prognosis.

Adult↗
PubMed1988

[Detection of ischemia with thallium-201 single photon emission computerized tomography (SPECT) and radionuclide ventriculography in comparison with stress cineventriculography].

The accuracy of radionuclide techniques for detection of exercise-induced myocardial ischemia was analyzed with TL-201 single-photon emission computer tomography (SPECT) and gated blood pool ventriculography in 31 patients. Reversible and persistent perfusion defects in the biphasic SPECT studies, parametric phase and amplitude images and global indices of left ventricular function were evaluated and compared to the results of exercise cineventriculography. Out of 25 patients with coronary heart disease, 20 had exercise-induced ischemia and 17 patients had a prior myocardial infarction. SPECT detected ischemia with a sensitivity of 85% and a specificity of 100%, gated blood pool ventriculography had a sensitivity of 60% and a specificity of 91%. Both scintigraphic methods were comparable in the detection of myocardial infarcts (SPECT/gated blood pool ventriculography: sensitivity 88%/82%; specificity 100%/93%; positive predictive value 100%/93%). A difference in detection of ischemia between both methods was found in patients with myocardial infarct and additional ischemia: all patients with additional ischemia were detected by SPECT, whereas gated blood pool ventriculography failed to identify the additional ischemia in 1/4 of these patients (p less than 0.05).

Cardiac Output↗
PubMed1988

[Quantitative segmental analysis of wall function of the right ventricle in probands with healthy hearts].

To investigate and determine the local wall motion of normal right ventricles, biplane angiograms from 14 normal subjects were analyzed. In all patients, organic heart disease was excluded by angiography and right heart catheterization under exercise. Using a radial model, segmental systolic area shortening was determined for the anterior, anteroapical and inferior segment in the RAO-projection and the inferior, anteroapical and anterior (free wall) segment in the LAO-projection. The highest segmental shortening was found for the anterior wall in the RAO-projection (45.6 +/- 7.8%) and for the free wall in the LAO-projection with 42.7 +/- 11.3% (RAO: anteroapical 28.1 +/- 6.3%; inferior: 26.5 +/- 7.8%. LAO: anteroapical: 34.7 +/- 18.8%; inferior: 30.6 +/- 21.6%). Corresponding to these different segment shortenings, right ventricular contraction seems to have a disharmonic pattern in comparison to the left ventricle. Normal local wall motion of segmental area shortening was predicted by the means-2SD (95.5%) confidence interval. The confidence interval of the inferior (-12.6%) and anteroapical (-2.9%) segment in the LAO-projection was poor compared to the other segments (RAO: anterior 30.0%; anteroapical 15.5%; inferior: 10.9%; LAO: free wall: 20.1%). For the LAO-inferior and LAO-anteroapical segment, even akinesia was within the 95.5% confidence interval. In conclusion, quantification of local wall motion seems possible with reasonable confidence for RAO segments and the free wall in the LAO-projection only.

Aged↗