[TEE-guided cardioversion in patients with atrial fibrillation without previous anticoagulation]. / TEE-geführte Kardioversion bei Patienten mit Vorhofflimmern ohne vorherige Antikoagulation.

A total of 332 patients (mean age 65+/-10 years, 86 female) with nonvalvular atrial fibrillation (AF) of more than 48 hours duration and lack of a sufficient anticoagulation were included. After exclusion of thrombotic material in the left atrium using transesophageal echocardiography (TEE) cardioversion (CV) was performed within 24 hours. At the same time oral anticoagulation (AC) (overlapping with PTT-affecting heparinisation) was started. If thrombi were found by TEE, the examination was repeated after at least four weeks of anticoagulation. If thrombi were absent at this time, CV was performed. Periprocedural embolism was defined as primary endpoint, whereas the detection of atrial thrombi before CV was defined as secondary endpoint. In 33 of the 332 Patients (9.9%) the TEE showed a thrombus in the left atrium respectively the left atrial appendage (n=22) or thrombi could not be excluded (n=11). 383 TEEs were performed without complications in an overall of 332 patients.A total of 305 CV were performed (electrical n=300, pharmacological n=5) and during periprocedural monitoring and in the time of four weeks after CV no thromboembolic complications were observed.TEE-guided CV in patients with AF persisting for more than 48 hours and without previous AC can be considered as a method that is both safe and effective.

Assessment of ventricular filling volumes with an automated color Doppler method: validation in a pulsatile flow model.

OBJECTIVE: Determination of ventricular filling volumes with the use of Doppler echocardiographic measurements critically depends on the presence of a circular-shaped flow area and a flat velocity profile across it because evaluation of flow volume is usually based on echocardiographic measurements of its diameter and pulsed Doppler recordings within the center of this area. The approach may be limited at the mitral and tricuspid ring levels as a result of their noncircular shape and because nonflat velocity profiles are present. The purpose of this study was to examine in a pulsatile flow model simulating ventricular inflow conditions the accuracy of an automated method based on the analysis of color Doppler flow velocities for evaluation of flow volumes. MATERIALS AND METHODS: A recently-developed automated Doppler method that takes into account the velocity distribution across a region of interest was examined in a pulsatile flow model by using flows with waveforms characteristic for ventricular inflow through tubes with elliptically-shaped cross-sectional areas. Color Doppler imaging was performed against flow direction along the major and minor axes of the tubes with major diameters ranging between 3 and 5 cm and major-to-minor diameter ratios of 1.5 and 2.0. RESULTS: A close correlation was found between flow volumes measured by the Doppler technique for registrations along the minor or major axis of the ellipses and actual values (r = 0.99, standard error of the estimate = 0.44 to 1.98 mL), with a systematic underestimation or overestimation, respectively, depending on the diameter ratio. Averaging of the data derived from 2 orthogonal measurements by using the geometric mean value yielded an excellent agreement between Doppler data and actual flow volumes. CONCLUSION: This automated color Doppler method enables reliable determination of flow volumes in a pulsatile flow model simulating ventricular inflow conditions with the use of 2 orthogonal imaging views. The data indicate that the method may improve the noninvasive evaluation of ventricular filling volumes.

Determination of prestenotic flow volume using an automated method based on colour Doppler imaging for evaluating orifice area by the continuity equation: validation in a pulsatile flow model.

OBJECTIVE: To evaluate, in a pulsatile flow model simulating flow conditions in valvar stenoses, whether accurate determination of orifice area can be achieved by the continuity equation using automated determination of flow volumes based on spatiotemporal integration of digital colour Doppler flow velocities. METHODS: A method for automated determination of flow volumes which takes into account the velocity distribution across a region of interest was examined using flow through a tube and various restrictive outlet orifices with areas ranging between 0.2 and 3.1 cm2. The sampling rectangle of the Doppler method was positioned proximal to the obstructions within the flow convergence zone for evaluating prestenotic flow volume. Stenotic jet velocities were recorded by continuous wave Doppler to obtain the integral under the velocity curve. Prestenotic flow volume was then divided by the velocity integral to calculate functional orifice area according to the continuity equation. RESULTS: The presence of parabolically shaped velocity profiles across the prestenotic region was demonstrated by the Doppler method. Excellent agreement was found between prestenotic flow volumes measured by the Doppler technique and actual values (r = 0.99, SEE = 1.35 ml, y = 0.99x-0.24). Use of the continuity equation led to a close correlation, with a systematic underestimation of geometric orifice sizes. Correction of Doppler data for flow contraction yielded an excellent agreement with actual orifice areas. CONCLUSIONS: The study validated the accuracy of a Doppler method for automated determination of flow volumes for quantifying orifice area by the continuity equation. Prestenotic flow volume and functional orifice area could be evaluated reliably in the presence of non-flat velocity profiles. Thus the method contributes to the non-invasive assessment of valvar stenoses.

Acute alterations of oxygen uptake and symptom-limited exercise time in patients with mitral stenosis after balloon valvuloplasty.

STUDY OBJECTIVES: To determine the acute influence of improvement in orifice area in mitral stenosis by percutaneous transluminal valvuloplasty (PTVP) on cardiopulmonary exercise capacity, treadmill walking time (TWT), oxygen uptake parameters at maximum exercise as well as at highest comparable workloads and parameters of breathing work were assessed pre- and post-PTVP. PATIENTS AND INTERVENTIONS: PTVP was carried out in 16 patients who had moderately severe mitral stenosis, bringing about an average increase in mitral valve orifice area from 1.0 +/- 0.1 cm2 to 2.2 +/- 0.5 cm2 (p < 0.0005). Based on standardized conditions, the patients (six in functional class A, five in class B, and five in class C according to Weber's classification) underwent symptom-limited treadmill cardiopulmonary exercise testing before as well as 2 days after PTVP. In addition, subgroup analysis (eight patients in sinus rhythm, eight patients in atrial fibrillation) was performed to determine a potential influence of the underlying cardiac rhythm on cardiopulmonary exercise parameters. To rule out a PTVP-independent training effect, a control group of ten patients with mitral stenosis underwent the same kind of cardiopulmonary exercise testing on 2 consecutive days. MEASUREMENTS AND RESULTS: After-PTVP, TWT augmented by 19% (p < 0.0005) in all patients. Maximum oxygen uptake in percent of predicted maximal values at peak exercise and at anaerobic threshold was enhanced by 10% (p < 0.005). Ventilation at highest comparable workload was diminished by 10% (p < 0.025), whereas oxygen uptake and oxygen pulse at highest comparable workload did not differ, reflecting both unaltered cardiac output at comparable workloads and a more economic ventilation, respectively. Furthermore, PTVP-mediated alterations of TWT, but not of oxygen uptake at peak exercise were more pronounced in patients in sinus rhythm than in those in atrial fibrillation, reflecting more effective economization of cardiac work and ventilation in the former subgroup. Except for a statistically significant increase of TWT of 5%, no clinically relevant differences between both exercise tests were found with respect to oxygen uptake in the control group. CONCLUSIONS: Impaired cardiopulmonary fitness in patients with moderately severe mitral stenosis is improved substantially by PTVP immediately after the intervention, mainly the result of acute reduction of pulmonary congestion and subsequent decrease in dead space to tidal volume ratio. Adherence to standardized conditions is considered crucial for comparability of cardiopulmonary data.

Safety of transesophageal echocardiography. A multicenter survey of 10,419 examinations.

BACKGROUND: During the past few years, transesophageal echocardiography (TEE) has been increasingly used in clinical cardiology; data concerning the practicability and safety of the technique, however, are rare. METHODS AND RESULTS: This report analyzes the experience of 15 European centers performing TEE studies for at least 1 year. At the time of this survey, 10,419 TEE examinations had been attempted or performed in these institutions. These TEE examinations were carried out by 54 physicians, 53.7% of whom had been trained in endoscopic techniques. Within the same time period, 160,431 precordial echocardiographic examinations were performed in the 15 institutions; the ratio between TEE and transthoracic studies averaged 9.03 +/- 6.4% (range of the 15 centers, 1.4-23.6%). Of the 10,419 patients, 9,240 (88.7%) were conscious inpatients or outpatients at the time of the TEE examination; the vast majority of the conscious patients did not receive intravenous sedation before TEE. In 201 cases (1.9%), insertion of the TEE probe was unsuccessfully attempted because of a lack of patient cooperation and/or operator experience (98.5%) or because of anatomical reasons (1.5%). In 90 of 10,218 TEE studies (0.88%) with successful probe insertion, the examination had to be interrupted because of the patient's intolerance of the echoscope (65 cases); because of pulmonary (eight cases), cardiac (eight cases), or bleeding complications (two cases); or for other reasons (seven cases). One of the bleeding complications resulted from a malignant lung tumor with esophageal infiltration and was fatal (mortality rate, 0.0098%). CONCLUSIONS: This multicenter survey documents that TEE studies are associated with an acceptable low risk when used by experienced operators under proper safety conditions.

[Echocardiographic and Doppler echocardiographic characterization of left ventricular diastolic function]. / Echokardiographische und Doppler-echokardiographische Charakterisierung der linksventrikulären diastolischen Funktion.

For noninvasive assessment of diastolic ventricular function, in addition to echocardiography, more recently, in particular, Doppler echocardiography has been employed. M-mode echocardiogram velocity curves for diameter changes as well as Doppler-echocardiographically registered velocity curves of mitral flow characterize the temporal changes of diastolic flow into the left ventricle. They represent the overall result of factors which influence diastolic filling and are functions of the temporal course of the pressure difference between left atrium and left ventricle. Registration of M-mode and Doppler echocardiograms: For determination of M-mode parameters which should describe left ventricular diastolic function, in addition to the motion of the mitral valve, the left ventricular contours of septum and posterior wall between mitral leaflets and papillary muscles are recorded together with the ECG. For evaluation of the index of atrial emptying, an M-mode registration is obtained from the region of the aortic root. Determination of the Doppler echocardiographic parameters is based on analysis of the blood flow velocity in the region of the mitral valve in the apical four-chamber view with the pulsed Doppler method. Additionally, simultaneous to the Doppler curve, a phonocardiogram is registered or, alternatively, a continuous-wave Doppler registration is obtained which delineates the left ventricular outflow signal and the artefact of mitral valve opening. Parameters for characterization of left ventricular diastolic filling: The first peak of the velocity curve of the diameter change in the M-mode echocardiogram corresponds with the maximal diameter change resulting from early-diastolic filling and the second peak with the maximal diameter change of the left ventricle associated with atrial filling. From this curve as well as the diameter curve relative to time and the mitral valve motion, the times for isovolumetric relaxation as well as the rapid, slow and atrial filling phase which characterize the ventricular filling and the diameter changes of the left ventricle during these time intervals can be derived. The maximal velocity of the diastolic diameter change (PFR) is used to characterize the maximal early diastolic flow. The atrial emptying index characterizes the fraction of filling volume in the first third of diastole with respect to total filling volume of the left ventricle. As an indirect parameter for description of the early-diastolic filling, the steepness of the early-diastolic closure of the anterior mitral leaflet is used. From Doppler velocity profiles of the mitral inflow, early and late diastolic maximal velocities and their velocity time integrals as well as the relationships of these parameters to each other are determined.(ABSTRACT TRUNCATED AT 400 WORDS)

[Color Doppler sonography (angiodynography) in the assessment of the arterial vascular bed of the lower extremities]. / Farb-Doppler-Sonographie (Angiodynographie) zur Beurteilung der arteriellen Gefässstrombahn der unteren Extremitäten.

With color Doppler ultrasonography, since its inception two years ago, through combination of color-coded flow and gray-coded vessel and tissue imaging, a new technique is available with which, based on the information derived from the Doppler principle, characterization is enabled of the direction of blood flow coded in red or blue, the velocity in varying color intensities and turbulent flow through color mixing. For determination of the velocity of flow at any point in the vessel, additionally, the pulsed Doppler method is available. The diagnosis of obstruction is based on delineation of plaques in the vascular lumen as well as changes in profile of the flowing blood. Color Doppler ultrasonography enables differentiation of high-grade stenosis from occlusion, aids and rapid localization of a stenosis and permits correction of the angle between the Doppler beam and flow in the vessel without providing quantitative evaluation of the degree of stenosis; the latter, however, can be mediated from the recorded velocity profile of the pulsed Doppler method Through demonstration of color-coded blood flow, the patency of bypass grafts can be documented. Additionally, information can be obtained with regard to the proximal and distal anastomoses, flow patterns in the region of preserve venous valves, stenoses and arterio-venous fistulas. Pseudoaneurysms are seen as cavity-like perivascular structures devoid of echo signals, the contiguous access to the lumen of which can be verified by display of pulsatile, systolic-diastolic flow in the color-coded image. With color Doppler ultrasonography abnormal flow patterns incurred through atherosclerotic changes in the vessel wall, stenoses, anastomoses, aneurysms and pseudoaneurysms can be reliably detected.(ABSTRACT TRUNCATED AT 250 WORDS)

[Doppler echocardiographic findings before and after balloon catheter valvuloplasty in mitral stenosis]. / Doppler-echokardiographische Befunde vor und nach Ballonkathetervalvuloplastie bei Mitralstenose.

This study was undertaken to analyze the diagnostic value of Doppler echocardiographic determination of pressure gradient and valve orifice area for the evaluation of balloon valvuloplasty in mitral stenosis as well as the echocardiographic assessment of calcification, leaflet motion and the subvalvular apparatus for characterization of the most favorable morphologic prerequisites for this procedure. Doppler echocardiographic studies were performed in 24 patients with mitral stenosis, 21 women and three men, age range from 29 to 79 years, mean age 55 years, one day before and after balloon valvuloplasty and the results were compared with invasively-determined hemodynamic measurements. The Doppler echocardiographic determination of the mean pressure gradient before and after balloon valvuloplasty was carried out with the modified Bernoulli equation from the velocity profile of the stenotic jet and calculation of the mitral valve orifice area using the pressure half-time method. Echocardiographic assessment of valve morphology and motion was based on two-dimensional echocardiographic cross-sectional images. Calcification, as observed in the parasternal cross-sectional image, was classified as absent (grade 0), slight to moderate (grade 1) or severe (grade 2). Motion of the valve leaflets, as judged from the apical four- and two-chamber views, was assigned one of five grades taking into consideration the motion of the bodies of both leaflets from the systolic baseline position as less than 10 degrees, between 10 and 45 degrees and more than 45 degrees. The subvalvular apparatus, that is the chordae and the papillary muscles, were graded as unremarkable (grade 0), slightly altered (grade 1) and markedly altered (grade 2). Using a score derived by adding the grade of these three criteria, a formal value between 0 and 8 was calculated. Hemodynamic measurements were carried out with standard techniques employing simultaneous registrations of left atrial and left ventricular pressure for evaluation of the mean diastolic pressure gradient. Determination of the stroke volume was based on biplane left ventriculograms using Simpson's rule. The valve orifice area was calculated according to the Gorlin formula. Dilatation was carried out with a Bifoil (12F, balloon diameter 2 X 19 mm) or Trefoil (10F, 3 X 12 mm) valvuloplasty catheter. After PTVP, on comparison of the Doppler-echocardiographically determined pressure gradient (5.7 +/- 1.9 mm Hg) with that determined invasively (6.4 +/- 3.2 mm Hg) there was a moderate correlation (n = 19, r = 0.74, SEE = 1.3 mm Hg) where the noninvasively-determined values, in general, were smaller.(ABSTRACT TRUNCATED AT 400 WORDS)

[Doppler echocardiography in the evaluation of the results of balloon catheter valvuloplasty in aortic valve stenosis]. / Doppler-Echokardiographie zur Beurteilung des Ergebnisses von Ballonkathetervalvuloplastien bei Aortenklappenstenose.

This study was undertaken to assess the diagnostic value of Doppler echocardiographic methods for determination of the mean pressure gradient and valve orifice area in the evaluation of the results of balloon valvuloplasty (PTVP) in aortic stenosis by comparison with invasively-determined measurements. In 16 patients with aortic valve stenosis, eight men and eight women, mean age 64 +/- 10 years, Doppler echocardiographic studies were performed one day before and after PTVP. The mean pressure gradient was calculated with the aid of the modified Bernoulli equation and the aortic valve orifice area with the continuity equation. After PTVP, on comparison of Doppler echocardiographic and invasively-determined pressure gradients, there was no significant correlation (n = 16, y = 0.3x + 18.7, r = 0.36, SEE = 9.3 mm Hg) (Figure 2). Prior to PTVP the two methods correlated reasonably well with each other (n = 16, y = 0.6x + 7.7, r = 0.54, SEE = 17.8 mm Hg) (Figure 2). On comparison of the Doppler echocardiographic and invasively-determined aortic valve orifice area, both after and before PTVP, there were significant linear correlations (n = 8, y = 0.41x + 0.41, r = 0.73, SEE = 0.12 cm2 and n = 14, y = 0.71x + 0.17, r = 0.86, SEE = 0.10 cm2, respectively) (Figure 4). Correspondingly, there was close agreement between the change in absolute aortic valve orifice areas determined invasively (0.18 +/- 0.15 cm2) and noninvasively (0.15 +/- 0.10 cm2, n = 8).(ABSTRACT TRUNCATED AT 250 WORDS)

[Grading of the aortic valve regurgitation with the color Doppler echocardiography]. / Zur Schweregradbeurteilung von Aortenklappenregurgitationen mit Hilfe der Farb-Doppler-Echokardiographie.

This study was undertaken to assess whether various parameters of the extension of aortic regurgitation with color Doppler imaging are comparable with angiographic techniques for classification of severity. In 39 patients with aortic regurgitation, 14 women and 25 men, mean age 53 +/- 14 years, Doppler echocardiographic examinations were performed prospectively for determination of length, width and area of the maximal extension of regurgitant flow (Figure 1). Angiographic assessment of severity showed grade I regurgitation in nine, grade II in 14, grade III in twelve, and grade IV in four patients. The length of regurgitant flow in the color Doppler image showed an increasing tendency with increasing angiographic severity (r = 0.38, SEE = 13 mm), however, for various grades of severity, there was clear overlap. The area of regurgitation, similarly, due to substantial overlap, correlated only weakly with the angiographic data (r = 0.54, SEE = 196 mm2). To date, there is not theoretical basis for a correlation of the length and area of regurgitant flow with the severity and experimental studies have shown that there is no simple relationship. The best correlation was found for the width of the regurgitant flow (r = 0.63, SEE = 3 mm), however, here as well, there was clear overlap of data such that there was no statistically significant difference between grades II and III. Unequivocal differentiation of the values could only be achieved between grades I and IV. Based on a width of 7 mm, high-grade regurgitation could be detected with a sensitivity of 75% and a specificity of 74%.(ABSTRACT TRUNCATED AT 250 WORDS)

[Doppler echocardiography determination of the orifice area in aortic valve stenosis using a continuity equation]. / Doppler-echokardiographische Bestimmung der Offnungsfläche bei Aortenklappenstenose unter Anwendung der Kontinuitätsgleichung.

The continuity equation, derived from the study of fluid mechanics, may serve as the basis for calculation of orifice area of stenosed cardiac valves. As applied to aortic stenosis, the continuity equation states that the flow across the narrowed valve is equal to the flow in the left ventricular (LV) outflow tract such that A1 X v1 = A2 X v2, where A1 = LV outflow tract area, v1 = prestenotic velocity, A2 = stenotic orifice area and v2 = poststenotic velocity. Accordingly, at each point in time during pulsatile flow, the respective valve orifice area can be calculated. Hence, from the sum of all areas throughout the ejection time, the mean valve orifice area can be constructed as integral of A2/ET = A1 X integral of (v1/v2)/ET, assuming A1 to be constant, where integral of denotes the integral over the ejection time ET. To assess the usefulness of this method with respect to its clinical relevance, in 36 patients with aortic stenosis, the Doppler echocardiographically-determined orifice areas were compared with those calculated by the Gorlin formula based on invasively-obtained data. LV outflow tract area A1 was measured by echocardiography from a parasternal long-axis view. Prestenotic velocity v1 was recorded in the LV outflow tract by pulsed Doppler from an apical transducer position, whereby care was taken in positioning the sample volume not too close to the stenotic valve to avoid the prestenotic area of increased velocity. Continuous-wave Doppler was used, usually from an apical or right parasternal transducer position, to record the stenotic jet velocity v2.(ABSTRACT TRUNCATED AT 250 WORDS)

[Doppler echocardiography determination of the pressure gradient and valve orifice area in mitral valve stenosis]. / Doppler-echokardiographische Bestimmung von Druckgradient und Klappenöffnungsfläche bei Mitralstenose.

Pressure gradient and orifice area of stenosed mitral valves can be determined with Doppler echocardiography using the modified Bernoulli equation and the pressure half-time method, respectively (Figures 1 and 2). There was a close linear correlation between Doppler-echocardiographically determined pressure gradients and valve orifice areas with those obtained by invasive methods. In this study, in 85 patients with mitral stenosis of various severity, the valve orifice areas, as derived by the two methods respectively, correlated well (y = 0.89x + 0.15) with a correlation coefficient r = 0.96 and standard error of the estimate SEE = 0.12 cm2 (Figure 3). The correlation was not influenced by the prevailing cardiac rhythm, ventricular function, left ventricular mass or coexistent mitral or aortic regurgitation (Table 1). Accordingly, the Doppler echocardiographic method also appears applicable in the presence of concomitant mitral and aortic regurgitation which precludes an exact determination of valve orifice area with invasive methods. The Doppler echocardiographic method is currently so well validated that it can be regarded as a reliable noninvasive procedure for determination of the severity of mitral stenosis.

[Doppler echocardiography determination of the severity of tricuspid valve stenosis]. / Doppler-echokardiographische Bestimmung des Schweregrades der Trikuspidalstenose.

To evaluate the diagnostic usefulness of Doppler echocardiography for assessment of tricuspid stenosis, data of eleven patients were compared with hemodynamic results. Using the pressure half-time method, stenotic tricuspid orifice area was calculated as the quotient of 220 divided by the pressure half-time. The pressure gradient across the stenotic valve was determined according to the modified Bernoulli equation using four times the square of the maximal velocity of the stenotic jet. A close correlation was found between the Doppler echocardiographically and invasively determined orifice areas (r = 0.97, SEE = 0.23 cm2). There was also a good linear relationship between the pressure gradients derived from both methods (r = 0.89, SEE = 1 mmHg). Thus, the assessment of tricuspid stenosis can be achieved reliably by noninvasive means with the aid of Doppler echocardiography.

[Noninvasive determination of the orifice area of aortic valve prostheses using Doppler echocardiography]. / Nichtinvasive Bestimmung der Offnungsfläche von Aortenklappenprothesen mit Hilfe der Doppler-Echokardiographie.

In aortic valve stenosis, Doppler echocardiography enables reliable estimation of the orifice area with the use of the continuity equation. This study was carried out to determine the usefulness of the method in evaluation of prosthetic aortic valve area. Accordingly, 32 patients with normally-functioning mechanical Björk-Shiley prostheses underwent Doppler investigations two to three weeks after aortic valve replacement. Pre(v1)- and post(v2)-prosthetic velocities were recorded by pulsed and continuous-wave Doppler, respectively, and the prosthetic annulus used as cross-sectional area of flow (A1). For calculation of prosthetic orifice area (A2), the continuity equation at peak flow (v1,p) was employed where A2 = A1 X v1,p/v2 (at the point in time of v1,p). Mean pressure gradients across the prostheses were determined with the use of the modified Bernoulli equation. In addition, the ratio of acceleration to ejection time (AT/ET) was derived from the velocity profile of v2. Consistent with increasing prosthetic sizes (A 23 to A 29), there were increases in the calculated orifice areas A2 (A 23: 1.46 +/- 0.26, A 25: 1.71 +/- 0.24, A 27: 2.12 +/- 0.26, A 29: 2.53 +/- 0.35 cm2). Albeit with a substantial overlap between the various sizes, mean values for the respective sizes differed statistically significant and were comparably within the range established by in-vitro measurements. Pressure gradients across the prostheses were also different for the various sizes and were within the range reported from hemodynamic studies. In contrast, the AT/ET-ratio showed no significant difference between different prosthetic sizes.(ABSTRACT TRUNCATED AT 250 WORDS)

[On the topic: Doppler echocardiography]. / Zum Thema: Doppler-Echokardiographie.

With Doppler echocardiography, in addition to delineation of cardiac structures and their motion, intracardiac pressure and blood flow characteristics can also be assessed. The theoretical basis for this diagnostic method had been formulated by Christian Doppler approximately 100 years prior to its initial use for measuring blood flow in the heart with the aid of ultrasonic waves. The development of continuous-wave Doppler which subsequently yielded the capability for determination of the direction of blood flow, was followed by the development of pulsed Doppler for measurement of blood flow velocity in localized regions of the heart. Inter-currently, combinations of pulsed Doppler together with echocardiography as well as that of pulsed and continuous-wave Doppler were successfully incorporated into a single unit. The most recent development is represented by the realization of color Doppler systems. The possible applications of Doppler echocardiography in cardiology are manifold. Stroke volume and cardiac output determinations are based on measurement of the velocity profile in a specified region of the heart or neighboring great vessels and calculation of the respective area of flow. Intracardiac pressures can be determined in the presence of valvular stenosis, regurgitation or shunt using the pressure differences between contiguous cardiac or vascular structures as calculated by the modified Bernoulli equation and the clinically-measurable or estimable pressure in one of the respective areas. Further methods encompass parameters which can be obtained with the aid of the velocity profile of the pulmonary flow. While two-dimensional echocardiography remains the standard for assessment of systolic left ventricular function, evaluation of diastolic function can be achieved with Doppler echocardiography based on parameters of mitral inflow.(ABSTRACT TRUNCATED AT 250 WORDS)

[Doppler-echocardiographic determination of the degree of severity of mitral stenosis]. / Doppler-echokardiographische Bestimmung des Schweregrades der Mitralstenose.

The assessment of severity of mitral stenosis is generally based on the mitral valve orifice area as calculated by the Gorlin formula from the invasively-measured pressure gradient and flow across the valve. As an additional reference for evaluating severity, the hemodynamically-determined pressure half-time has been suggested; that is, the time required for the peak gradient across the stenotic valve to drop to one-half of its original value. Since the pressure gradient and the velocity of flow in the region of the stenosis are related to each other as described in the Bernoulli equation and, since the velocity of flow can be analyzed with Doppler echocardiography, the possibility is afforded for noninvasive determination of both the pressure gradient and the pressure half-time. From the Doppler echocardiographically determined pressure half-time, the mitral valve orifice area can be calculated. This study, in a relatively large population of patients with mitral stenosis, was undertaken to compare the pressure half-times obtained from Doppler echocardiography with the valve orifice areas derived from hemodynamic measurement, to analyze the relationship between the two latter parameters and to evaluate the relevance of the newly-developed method. In Doppler echocardiography, the frequency shift of emitted sound reflected from moving blood cells is measured. The velocity of blood flow is proportional to the frequency shift delta f.(ABSTRACT TRUNCATED AT 250 WORDS)