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At least 73 records · Page 4Linked to original sources

PubMed2001

Use of peak Doppler gradient across ventricular septal defects leads to underestimation of right-sided pressures in patients with "sloped" Doppler signals.

In patients with "sloped" appearance of the Doppler signal across a ventricular septal defect (VSD), the peak Doppler velocity seems to overestimate the catheterization-derived peak-to-peak gradient, resulting in underestimation of right-sided heart pressures. In 11 patients with sloped Doppler signals across the VSD, ventricular pressure tracings were compared with simultaneous recordings of the Doppler signal. The average peak Doppler gradient (40.2 +/- 19.2 mm Hg) overestimated the catheterization-derived peak-to-peak gradient (20.2 +/- 13.6 mm Hg) significantly (P < or =.001). Doppler mean gradient (20.2 +/- 11.3 mm Hg; P = ns) and end-systolic gradient (17.0 +/- 12.5 mm Hg; P < or =.05) were closer estimates of the catheterization peak-to-peak gradient. All Doppler gradients showed good correlation to the catheterization peak-to-peak gradient with r2 values of 0.77, 0.73, and 0.91. We conclude that Doppler mean or end-systolic gradients should be used for calculation of right-sided heart pressures in this patient population.

Cardiac Catheterization↗

PubMed2004

Basic study on velocity-flow urodynamics using Doppler sonography: simultaneous detection of cavitation and Doppler signals in an artificial urethral model.

BACKGROUND: We have developed velocity-flow urodynamics using Doppler sonography based on the hypothesis that microbubbles formed in the urethra are responsible for Doppler signals. In order to confirm this hypothesis derived from Bernoulli's principle, we investigated the simultaneous detection of cavitation noise and Doppler signals in an experimental system. METHODS: An experimental circuit was built in which a stenosis was created using a glass or silicon tube with tap water used as the sample fluid. Doppler signals, pressure before and after the stenosis, flow rate, flow velocity and cavitation noise were measured. Direct detection of cavitation with a high-speed charged-coupled device (CCD) camera was conducted in the glass tube. The relationship between cross-sectional area and flow velocity in terms of the detection of Doppler signals was analyzed in the silicon tube study. RESULTS: In the glass tube study, a high-speed CCD camera clearly detected masses of microbubbles associated with cavitation. The range of flow rates creating cavitation completely corresponded with those producing Doppler signals detected by ultrasonography. A similar correlation was observed in the silicon tube study, which showed that a low flow velocity of 41.5 cm/sec through a stenosis with a cross-sectional area of 20 mm(2) created Doppler signals at a flow rate of 8.3 mL/sec. CONCLUSION: The results of the present study confirmed that microbubbles created in flowing urine are responsible for Doppler signals. Measurement of velocity-flow urodynamics has great potential to become a non-invasive and reliable alternative to conventional pressure- flow urodynamic studies.

Humans↗

PubMed1997

A randomised controlled trial of Doppler ultrasound velocimetry of the umbilical artery in low risk pregnancies. Doppler French Study Group.

OBJECTIVE: To evaluate the effect on management and outcome of pregnancy of routine umbilical Doppler examination in low risk populations. DESIGN: Pragmatic randomised controlled trial. SETTING: Twenty centres caring for low risk pregnant women. PARTICIPANTS: 4187 women were randomly assigned to umbilical Doppler between 28 and 34 weeks of gestation or no routine umbilical Doppler. The women included were at low risk at 28 weeks of gestation defined by a normal ultrasonographic examination at the time of randomisation and no obstetric or medical complications during the first two trimesters of the pregnancy. RESULTS: The general characteristics at inclusion were comparable for the two groups. Performance of umbilical Doppler led to a significant increase in the number of ultrasonographic and Doppler examinations subsequently conducted; there were no other effects on the management of the pregnancy. There was no significant difference in fetal distress during labour (odds ratio [OR] 0.96; 95% confidence interval [CI] 0.70-1.33). There were three times fewer perinatal deaths in the Doppler group (three versus nine), but this difference was not significant (OR 0.33; 95% CI 0.06-1.33). CONCLUSION: Based on this trial routine use of umbilical doppler for low risk pregnancy cannot be recommended. More data are needed to reach a definite conclusion of the value of routine Doppler.

Adult↗

PubMed1990

Pitfalls in the display of color Doppler jet areas: combined variability due to Doppler angle, frame rate, and scanning direction.

UNLABELLED: The Doppler color jet area depicting a regurgitant or shunt lesion may be useful in estimating its severity. However, color jet area may be affected by technical factors. We studied the combined effects of Doppler angle, frame rate, and scanning direction on the Doppler color jet area of a free jet with 10-mL injection. RESULTS: (1) Angle effects: color flow area was 11.7 +/- 2.0 cm2 at a Doppler angle of 20 degrees , and 2.3 +/- 1.2 cm2 at an angle of 60 degrees , when other parameters were kept constant (frame rate = 12 frames/sec, reverse scanning direction). (2) Frame rate effects: with other parameters kept constant (Doppler angle = 20 degrees , reverse scanning direction), color flow area was 11.7 +/- 2.0 cm2 at a rate of 12 frames/sec and 6.5 +/- 1.8 cm2 at 6 frames/sec. (3) Scanning direction effects: with other parameters kept constant (Doppler angle = 20 degrees , frame rate = 9 frames/sec), color flow area was 7.3 +/- 1.1 cm2 with scanning in the reverse direction, and 20.5 +/- 1.6 cm2 with scanning in the forward direction. (4) Combined effects: In our in vitro studies, the maximum color flow area was 20.5 +/- 1.6 cm2, and the minimum area was 1.5 +/- 0.2 cm2 (nearly twelve-fold). CONCLUSIONS: Doppler color jet area correlated inversely with Doppler angle (P less than 0.01) and directly with frame rate (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiography, Doppler↗

PubMed1998

Power Doppler sonography for hepatocellular carcinoma: factors affecting the power Doppler signals of the tumors.

AIMS/BACKGROUND: A recent advancement in Doppler ultrasonography (US) is power Doppler for detecting low-velocity blood flow at the microvascular level with angle independence. The present study was performed to characterize the factors contributing to the power Doppler signals of hepatocellular carcinoma (HCC). METHOD: Correlation of Doppler signals of HCC in 114 patients with 178 HCC nodules was analyzed in relation to the findings of CT and angiography, tumor characteristics (size, echo pattern, and histological differentiation of tumor), viral markers and severity of liver disease. RESULTS: The sensitivity of power Doppler US was superior to that of CT and angiography (each p<0.05; McNemar's test). The detection rate of power Doppler signal was significantly higher in tumors with diameter > or =2 cm (vs <2 cm in diameter), and with low/mixed echo pattern (vs high echo appearance), and with moderately/poorly differentiated HCC (vs well-differentiated HCC). Univariate analysis revealed that echo pattern, tumor size and histological differentiation of HCC in addition to CT and angiographic findings were significant. Multivariate analysis showed that tumor size and differentiation were significant. CONCLUSION: These results indicate that tumor characteristics play an important role in power Doppler signals and that these could be assessed by the presence or absence of power Doppler signals.

Angiography↗

PubMed1996

Acute testicular torsion: comparison of unenhanced and contrast-enhanced power Doppler US, color Doppler US, and radionuclide imaging.

PURPOSE: To compare the usefulness of conventional color Doppler ultrasound (US), unenhanced and contrast material-enhanced power Doppler US, and radionuclide imaging in a model of acute testicular torsion. MATERIALS AND METHODS: Twenty rabbits underwent unilateral 360 degree testis torsion and contralateral orchiopexy. Gray-scale, color Doppler, and unenhanced and contrast-enhanced power Doppler US were performed 4-6 hours later. The side of torsion was determined, and intratestis flow was graded. Within 2 hours of US, technetium-99m pertechnetate was intravenously administered, the rabbits were killed, and the testes excised for radionuclide imaging. RESULTS: Intratestis perfusion was detected in 85% of torsed testes at US and radionuclide imaging. The side of torsion was correctly diagnosed in 25% of cases with radionuclide imaging and in 60% of cases with US. Power Doppler US demonstrated significantly greater intratestis flow in pexed than in torsed testes. Although the numbers of correct diagnosis with the three US modalities were similar, flow grades within torsed and normal testes were significantly different. CONCLUSION: Perfusion to torsed and normal testes was demonstrated equally well with color Doppler US, power Doppler US, and radionuclide imaging. Doppler US better depicted differences in intratesticular flow between torsed and normal testes.

Acute Disease↗

PubMed1989

Continuous wave Doppler echocardiographic measurement of prosthetic valve gradients. A simultaneous Doppler-catheter correlative study.

Studies correlating prosthetic valve gradients determined by continuous wave Doppler echocardiography with gradients obtained by cardiac catheterization have, to date, been limited to patients with mitral and tricuspid prostheses or have compared nonsimultaneous measurements. Simultaneous Doppler and catheter pressure gradients in 36 patients (mean age, 63 +/- 13 years) with 42 prosthetic valves (20 aortic, 20 mitral, one tricuspid, and one pulmonary) were studied. Catheter gradients were obtained using a dual-catheter technique. The simultaneous pressure tracings and Doppler flow velocity profiles were digitized at 10-msec intervals to derive the corresponding maximal and mean gradients. The correlation between the maximal Doppler gradient and the simultaneously measured maximal catheter gradient was 0.94 (SEE = 6), and that between the Doppler gradient and the simultaneously measured mean catheter gradient was 0.96 (SEE = 3). There were no significant differences in correlation between gradients for the 32 mechanical valves (maximal gradients: r = 0.95, SEE = 6; mean gradients: r = 0.96, SEE = 3) and the 10 bioprosthetic valves (maximal gradients: r = 0.89, SEE = 6; mean gradients: r = 0.93, SEE = 3). In patients with mitral prostheses, Doppler gradients correlated well with the corresponding catheter gradients obtained with direct measurement of left atrial pressure (maximal gradients: r = 0.96, SEE = 2; mean gradients: r = 0.97, SEE = 1.2). A close correlation between corresponding Doppler and catheter gradients also was found in patients with aortic prostheses (maximal gradients: r = 0.94, SEE = 6; mean gradients: r = 0.94, SEE = 3). Thus, continuous wave Doppler echocardiography can accurately predict the pressure gradient across prosthetic valves.

Aged↗

PubMed1996

Characterization of adnexal masses: combination of color Doppler and conventional sonography compared with spectral Doppler analysis alone and conventional sonography alone.

OBJECTIVE: To evaluate the importance of color Doppler combined with conventional sonography in characterizing adnexal masses and to compare the results with those of spectral Doppler analysis alone and conventional sonography alone. MATERIALS AND METHODS: One hundred and fifteen women with 132 adnexal masses (98 benign, three borderline, and 31 malignant) were prospectively studied with conventional and Doppler sonography (transabdominal in all patients and transvaginal in 111). Three methods differentiated benign from borderline and malignant masses. In the first, conventional sonography was used. In the second, conventional sonography was combined with color Doppler. In this method, the presence of color flow in an echogenic portion classified as indeterminate or malignant by conventional sonography indicated malignancy; the absence of color flow in an echogenic portion classified as indeterminant or malignant at conventional sonography indicated benignancy; the presence or absence of color flow in a regular wall or septum indicated benignancy. The third method used spectral Doppler analysis. Malignancy was indicated by a resistive index (RI) less than or equal to 0.4, a pulsatility index (PI) less than or equal to 1, or a peak systolic velocity (PSV) greater than or equal to 15 cm/sec. RESULTS: Using conventional sonography alone, accuracy was 83%, sensitivity was 88%, and specificity was 82%. Using conventional sonography and color Doppler, accuracy was 95%, sensitivity was 88%, and specificity was 97%. Using spectral Doppler analysis and an RI less than or equal to 0.4, accuracy was 77%, sensitivity was 18%, and specificity was 98%. For a PI less than or equal to 1, accuracy was 68%, sensitivity was 71%, and specificity was 67%. For a PSV greater than or equal to 15 cm/sec, accuracy was 72%, sensitivity was 47%, and and specificity was 81%. CONCLUSION: Adding color Doppler to conventional sonography produced a specificity and positive predictive value higher than those of conventional sonography alone. Specificity increased from 82% to 97% (p < .001), and positive predictive value increased from 63% to 91%. RI, PI, and PSV were of limited value.

Adnexal Diseases↗

PubMed1998

Color Doppler sonography in early renal transplantation follow-up: resistive index measurements versus power Doppler sonography.

OBJECTIVE: This study was designed to compare power Doppler images of perfusion with interlobar resistive index measurements obtained during the early monitoring of renal graft transplant to diagnose cortical perfusion abnormalities and assess prognosis. SUBJECTS AND METHODS: Thirty-one patients underwent color Doppler sonography (4-7 MHz and 7-10 MHz) on day 6+/-2 after renal transplantation. Cortical vessel density was assessed visually and classified as either normal or decreased. Twelve months after transplantation, the results of power Doppler imaging and the levels of resistive index were reviewed in light of clinical and laboratory findings, graft biopsy results, and functional outcome. RESULTS: No significant relationship was observed among power Doppler grades, levels of resistive index, and renal function. Power Doppler grades and resistive index levels failed to allow us to distinguish between tubulopathy and rejection. However, we found a statistically significant relationship between renal function at 12 months after transplantation and power Doppler grade (p = .04). CONCLUSION: This study suggests that color Doppler sonography is insensitive in revealing and in allowing radiologists to differentiate the causes of graft dysfunction. However, power Doppler sonography allows a prediction of the functional recovery of the graft at 12 months after transplantation not provided by resistive index levels.

Adult↗

PubMed2001

Pattern of Doppler flow indices at the carotid bifurcation: evaluation by hemodynamic color Doppler imaging.

OBJECTIVE: To visualize the spatial variation of Doppler indices, principally the pulsatility index, taken proximal to the carotid bifurcation and to evaluate their relationship to the geometry of the carotid bulb. METHODS: The pattern of ultrasonographic Doppler indices was studied in healthy volunteers by using hemodynamic color Doppler imaging, which computes and displays a Doppler index at each color pixel from a sequence of color Doppler image frames taken over several cardiac cycles. RESULTS: In carotid bulbs with laminar flow (n = 5), the spatial partitioning between low-resistance internal carotid artery and high-resistance external carotid artery flows could be followed over 5 cm upstream in the common carotid artery. However, normal reverse or vortex flows at the carotid bulb (n = 15) obliterated upstream flow partitioning within 2 cm of the flow divider The pulsatility index was neither laterally nor axially uniform in the common carotid artery. CONCLUSIONS: Localization of "core flow" where meaningful Doppler indices may be measured is determined by the expansion geometry of the carotid bulb and usually requires positioning of a small sample volume in the center of the lumen at least 3 cm upstream from the flow divider However, in the absence of reverse or vortex flows, placement of a spectral Doppler sample volume is best guided by hemodynamic color Doppler imaging.

Adolescent↗

PubMed2001

Assessment of endometrial receptivity by transvaginal color Doppler and three-dimensional power Doppler ultrasonography in patients undergoing in vitro fertilization procedures.

The objective of this study was to investigate the usefulness of transvaginal color Doppler and three-dimensional power Doppler ultrasonography for the assessment of endometrial receptivity. A total of 89 patients undergoing in vitro fertilization procedures were evaluated for endometrial thickness and volume, endometrial morphology, and subendometrial perfusion on the day of embryo transfer. Neither the volume nor the thickness of the endometrium on the day of embryo transfer had a predictive value for conception during in vitro fertilization cycles (P > .05). Patients who became pregnant were characterized by a significantly lower resistance index, obtained from subendometrial vessels by transvaginal color Doppler ultrasonography (resistance index = 0.53 +/- 0.04 versus 0.64 +/- 0.04, pregnant versus not pregnant, respectively; P < .05), and a significantly higher flow index (13.2 +/- 2.2 versus 11.9 +/- 2.4; P < .05), as measured by a three-dimensional power Doppler histogram. No difference was found in the predictive value of scoring systems analyzing endometrial thickness and volume, endometrial morphology, and subendometrial perfusion by color Doppler and three-dimensional power Doppler ultrasonography. The high degree of endometrial perfusion shown by color Doppler ultrasonography and on three-dimensional power Doppler histograms on the day of embryo transfer can indicate a more favorable endometrial milieu for successful in vitro fertilization.

Adult↗

PubMed2001

The clinical significance of antenatal pathological Doppler findings in the fetal middle cerebral artery in cases with peripheral reduced diastolic doppler flow but no absence of end-diastolic flow in the umbilical artery or fetal aorta.

PURPOSE: The effects of antepartum pathological Doppler findings in the fetal middle cerebral artery in cases with simultaneously peripheral reduced diastolic Doppler flow on perinatal outcome and the odds ratio of perinatal risks were studied. METHODS: 214 patients were examined by color Doppler ultrasound in relationship to complications in gestation and labor and fetal outcome. One thousand and seventy Doppler flow measurements of the middle cerebral artery, the umbilical artery and the fetal aorta between 28 and 40 weeks of gestation were performed. Sensitivity and odds ratio of synchronous cerebral pathological and peripheral pathological Doppler blood flow with regard to the prediction of intrauterine growth retardation, rate of cesarean section, preterm delivery and newborn depression was calculated. In all Doppler measurements there were no cases with absence of end-diastolic flow. RESULTS: Preterm delivery rate and intrauterine growth retardation rate were significantly higher in cases of synchronous cerebral pathological and peripheral pathological Doppler blood flow as in cases of isolated reduced peripheral blood flow (p<0.001; odds ratio 13.2 and 16.6). CONCLUSION: Pregnancies with no absence of end-diastolic flow in the fetal aorta or umbilical artery, but with reduced diastolic flow in these vessels and simultaneous pathological Doppler findings in the fetal middle cerebral artery are high risk pregnancies, above all in respect to intrauterine growth retardation, preterm delivery and newborn depression. Surveillance of pregnant women should be performed in a perinatal centre.

Aorta↗

PubMed1996

[Usefulness of color echo Doppler with power Doppler in the diagnosis of hypoechoic thyroid nodules: work in progress].

The aim of this study was twofold: first, to improve the predictive value of ultrasonography (US) in differentiating benign from malignant thyroid nodules and, second, to investigate whether color Doppler and power Doppler can distinguish different morpho-hemodynamic patterns of hypoechoic thyroid nodules according to their vascularity. Twenty-nine patients with hypoechoic thyroid nodule(s) were entered into this work in progress. Three typical power Doppler patterns were recorded and compared with color Doppler patterns and with cytologic and/or histologic findings. Power Doppler patterns were classified as follows: type A, a perilesional vascular halo; type B, a peri- and intralesional vascular halo, subdivided into: 1) with moderate intralesional vascularization, homogeneous structure and regular vessel caliber and 2) with rich intralesional vascularization, anarchical structure and winding vessel caliber and flow; type C, a perilesional vascular halo with a characteristic peripheral large afferent vessel characterized by winding caliber and flow. Of 29 patients, 21 had type A power Doppler (benign nodular goiter at cytology, in 4 of them with regressive phenomena); seven patients had type B power Doppler patterns-4 had a subtype 1 pattern (3 with nodular hyperplasias and 1 with a papillary adenoma), 3 had a subtype 2 (two had a follicular adenoma and one had a final diagnosis of angioinvasive follicular carcinoma). The patient with undifferentiated carcinoma had a type C power Doppler pattern. In conclusion, according to our early results, PD seems to be more sensitive and reliable than CD in the screening of thyroid nodules, and to yield better vascular information.

Adult↗

PubMed1988

Determination of left-sided pressure gradients by utilizing Doppler aortic and mitral regurgitant signals: validation by simultaneous dual catheter and Doppler studies.

Continuous wave Doppler echocardiography is an accurate and reproducible method for determination of intracardiac pressure gradients in stenotic valve lesions and right-sided regurgitant lesions. Twenty-three patients with either mitral or aortic regurgitation underwent simultaneous continuous wave Doppler and dual catheter pressure recordings to determine if instantaneous pressure gradients can be accurately determined by Doppler ultrasound in left-sided regurgitant valve lesions. Using the modified Bernoulli equation, the maximal and mean pressure gradients between the left ventricle and left atrium were determined by continuous wave Doppler ultrasound in patients with mitral regurgitation and compared with simultaneous catheter-derived pressures. The mean and end-diastolic pressure gradients between the aorta and left ventricle were determined by continuous wave Doppler ultrasound in patients with aortic regurgitation and compared with simultaneous catheter-derived pressures. Diastolic half-times by both continuous wave Doppler ultrasound and catheter pressures were compared in patients with aortic regurgitation. There was a linear correlation between the mean gradients in all patients (r = 0.94; SEE = 6 mm Hg) with a similar correlation between the instantaneous gradients (r = 0.98; SEE = 8 mm Hg). There was a linear correlation between diastolic half-times by catheter and Doppler ultrasound (r = 0.95; SEE = 39 ms). As with other valvular lesions, continuous wave Doppler echocardiography can be used in patients with mitral or aortic regurgitation to accurately determine intracardiac pressure gradients.

Adult↗

PubMed1988

Prediction of the severity of aortic stenosis by Doppler aortic valve area determination: prospective Doppler-catheterization correlation in 100 patients.

Two-dimensional and Doppler echocardiography was performed prospectively in 100 patients with aortic stenosis who were undergoing clinically indicated cardiac catheterization. The purpose of this study procedure was to determine various Doppler variables predictive of the severity of aortic stenosis and to compare Doppler- and catheterization-derived aortic valve areas. Doppler-derived mean gradient correlated well with corresponding gradient by catheterization (r = 0.86). Peak Doppler aortic flow velocity greater than or equal to 4.5 m/s and Doppler-derived mean aortic gradient greater than or equal to 50 mm Hg were specific (93 and 94%, respectively) for severe aortic stenosis (defined as catheterization-derived aortic valve area less than or equal to 0.75 cm2) but were not sensitive (44 and 48%, respectively). Doppler-derived aortic valve area calculated by the continuity equation correlated well with catheterization-derived aortic valve area calculated by the Gorlin equation when either the time-velocity integral ratio (r = 0.83) or the peak flow velocity ratio (r = 0.80) between the left ventricular outflow tract and the aortic valve was used in the continuity equation. A velocity ratio of less than or equal to 0.25 alone was sensitive (92%) in detecting severe aortic stenosis. Therefore, use of various Doppler-derived values allows reliable noninvasive estimation of the severity of aortic stenosis.

Aged↗

PubMed1983

[The Doppler Simulator DS 81. A new calibration method for ultrasound-cw-Doppler blood flow measurement devices].

Quality assurance in commercial cw-Doppler devices demands the use of special techniques in providing reproducible, optimized patient examination conditions for the individual instrument, and to permit a comparison with results obtained by other equipment. Equipment can be tested on two different technical levels: by checking the total performance by means of a Doppler phantom, or by testing the relevant components by means of electrical test signals. The use of Doppler phantoms involves certain drawbacks with respect to some equipment parameters and the routine equipment check. In the German Federal Republic, new official regulations (KBV), including the minimum requirements for Doppler equipment have been issued. To fulfil the legal requirements, a special test device, The Doppler Simulator DS 81 (1981), has proved suitable. The device provides a graduated scale of discrete, synthetic Doppler frequencies; these are fed into the Doppler equipment under test, and the response is recorded on the instrument's strip chart recorder or viewing screen. They are used as reference frequencies and for calibration. This method represents a further step towards reproducible or quantitative Doppler sonography.

Blood Flow Velocity↗

PubMed1995

Simultaneous measurement of pulmonary venous flow by intravascular catheter Doppler velocimetry and transesophageal Doppler echocardiography: relation to left atrial pressure and left atrial and left ventricular function.

OBJECTIVES: The aim of our study was to compare measurements of pulmonary venous flow velocity obtained either by transesophageal Doppler echocardiography or by intravascular catheter Doppler velocimetry. Furthermore, the relation among pulmonary venous flow velocity, left atrial compliance and left atrial pressure was evaluated. BACKGROUND: Data about the relation between left atrial pressure and pulmonary venous flow velocity are controversial. METHODS: A total of 32 patients undergoing elective open heart surgery for coronary artery bypass grafting were included prospectively in the study. Pulmonary venous flow velocity (Doppler catheter) and left atrial pressure (microtip pressure transducer) were recorded simultaneously with recordings of pulmonary venous flow velocity obtained by transesophageal Doppler echocardiography. RESULTS: Agreement between Doppler catheter and Doppler echocardiographic measurements of pulmonary venous flow velocity (n = 18 patients) was analyzed using the Bland-Altmann technique. The 95% limits of agreement were -0.16 to +0.11 m/s for systolic peak velocity, -0.14 to +0.09 m/s for diastolic peak velocity and -0.12 to +0.10 m/s for atrial peak velocity. The closest agreement between both methods was found for the ratio of systolic to diastolic peak velocity, the ratio of systolic to diastolic flow duration and the time from Q deflection on the electrocardiogram to maximal flow velocity. Mean left atrial pressure was strongly correlated with the ratio of systolic to diastolic peak velocity (r = -0.829), systolic velocity-time integral (r = -0.653), time to maximal flow velocity (r = 0.844) and the ratio of systolic to diastolic flow duration (r = -0.556). The ratio of systolic to diastolic peak velocity and the time to maximal flow velocity were identified as strong independent predictors of mean left atrial pressure. Left atrial compliance was not found to be an independent predictor of mean left atrial pressure. CONCLUSIONS: Flow velocity in the left upper pulmonary vein can be reliably recorded by transesophageal pulsed wave Doppler echocardiography. Our data reveal further evidence that mean left atrial pressure can be estimated by the pattern of pulmonary venous flow velocity.

Aged↗

PubMed2006

Doppler echocardiography and tissue Doppler imaging in the healthy rabbit: differences of cardiac function during awake and anaesthetised examination.

OBJECTIVE: In the past years, Doppler echocardiography has evolved into a commonly used technique. More recent sophisticated advances in imaging quality have substantially improved spatial and temporal resolution allowing the adaptation of this technique to small animal models, particularly in rabbits but even in mice. Recently, parameters obtained by Tissue Doppler Imaging (TDI) have been shown to be more independent of pre- and afterload than classic hemodynamic Doppler measurements. Exploration of animal models may require anaesthesia but there is only very little information on the effect of anaesthesia on echocardiographic parameters in rabbits. METHODS: We therefore performed Doppler-echocardiographic examinations of 20 wild-type New Zealand White rabbits in awake state and under light ketamine-xylazine anaesthesia. Special focus was put on the evaluation of global and regional left ventricular systolic and diastolic function using TDI and the myocardial performance index (Tei-index). RESULTS: Doppler-echocardiographic measurements including TDI in rabbits were feasible to assess cardiac morphology and function within a short examination time. There were some distinct changes of functional parameters during anaesthesia. Exemplary for systolic function, fractional shortening, cardiac output and systolic TDI velocity of the lateral wall decreased distinctly. Global left ventricular function measured by the Tei-index deteriorated. CONCLUSIONS: Doppler echocardiography and TDI can be performed easily, quickly and safely in the rabbit. Anaesthesia with the cardiodepressive ketamine-xylazine shows some distinct Doppler-echocardiographically measurable negative effects on cardiac function. Thus, echocardiography with less cardiodepressive anaesthetic regimes or even without anaesthesia after training of the animals should be considered as alternatives whenever possible.

Anesthesia↗