Continuous Wave Doppler Technique Research Articles

Quantitation of the Mitral Tetrahedron in Patients With Ischemic Heart Disease Using Real‐Time Three‐Dimensional Echocardiography to Evaluate the Geometric Determinants of Ischemic Mitral Regurgitation

Ischemic mitral regurgitation (IMR) is common in ischemic heart disease and results in poor prognosis. However, the exact mechanism of IMR has not been fully elucidated. Quantitation of the mitral tetrahedron using three-dimentianl (3D) echocardiography is capable of evaluating the geometric determinants and mechanisms of IMR. Forty patients with a history of ST-elevation myocardial infarction at least 6 months earlier were studied. Parameters of mitral deformation and global left ventricular (LV) function and shape were evaluated by 2-dimensional echocardiography. The effective regurgitant orifice (ERO) of IMR was obtained by the quantitative continuous-wave Doppler technique. Three-dimensional (3D) echocardiography was applied to assess the mitral tetrahedron. Mitral valvular tenting area (P < 0.001), mitral annular area (P = 0.032), dilation of the LV in diastole, impairment of the LV ejection fraction, and volume of the spherically shaped LV in systole were greater in patients with an ERO ≥20 mm(2) than in those with an ERO <20 mm(2). In the mitral tetrahedron, only the interpapillary muscle roots distance showed a significant difference (P = 0.004). Multivariate analysis with the logistic regression model showed the systolic mitral tenting area (odds ratio [OR]: 280.49, 95% confidence interval [CI]: 4.59-1.72 × 10(4), P = 0.007) and interpapillary muscle distance (OR: 1.50, 95% CI: 1.03-2.19, P = 0.036) to be independent factors in predicting significant IMR (ERO ≥20 mm(2)). 3D echocardiography can be effectively applied in measuring the mitral tetrahedron and evaluating the mechanism of IMR. Mitral valvular tenting and interpapillary muscle distance are 2 independent factors of significant IMR.

ISUOG Practice Guidelines: use of Doppler ultrasonography in obstetrics

<scp>ISUOG</scp> Practice Guidelines: use of Doppler ultrasonography in obstetrics

Rheumatic heart disease in Port Harcourt, Nigeria: clinical, demographic and echocardiographic features

Background : Rheumatic heart disease is endemic in developing countries especially sub- Saharan Africa. However, there is a growing impression that this disease has been eliminated. Availability of echocardiography with colour flow Doppler facilities has significantly improved diagnosis of cardiac diseases. This study aims at documenting the clinical and echocardiographic pattern of rheumatic heart disease in adult patients in Port Harcourt. Methods : A one-year (April 2009 to March2010) prospective analysis of the clinical profile and echocardiographic features of all the patients who had echocardiographically confirmed rheumatic valvular heart disease from our cardiac laboratory was undertaken. Trans-thoracic echocardiography was done using M-mode, two-dimensional, pulsed wave, continuous wave and colour flow Doppler techniques. Results : Twenty two cases of rheumatic valve disease were identified, thirteen males and nine females (M: F=1. 4:1). The age range was 17years to 68years with a mean age of 41.32 ± 16.14 years. The mean systolic blood pressure was 125.48 ± 26.46mmHg and mean diastolic blood pressure was 73.81± 18.57mmHg. The mitral valve was the most commonly involved valve (95.45%), one patient (4.54%) had only aortic valve involvement, eight (36.36%) had aortic and mitral valve involvement while thirteen (59.09%) had only mitral valve involvement. Fifteen patients presented in heart failure, three presented with palpitation and four presented with recurrent praecordial chest pain. Conclusion : Rheumatic heart disease remains prevalent among adult Nigerians in Port Harcourt presenting with heart disease. Males predominate and they present commonly in heart failure.

Continuous-Wave Doppler Ultrasound

Early noninvasive vascular diagnostic procedures relied heavily on continuous-wave (CW) Doppler ultrasound techniques. Development of CW Doppler instrumentation began in the mid 1950's in Japan with the work of physicist Shigeo Satomura. Donald Baker, an engineer at the University of Washington, working under the direction of pediatric cardiologist Robert F. Rushmer, lead a team that developed the first CW Doppler instrument in the United States in the early 1960's. CW Doppler instruments use two elements to continuously transmit ultrasound waves and to receive signals from moving reflectors within the ultrasound field. CW instruments are less costly and electronically less complex than pulsed Doppler systems. The major disadvantage of CW Doppler is the absence of depth discrimination. Display options include simple “audio” interpretation, analog recordings produced by a zero crossing detector, and spectral Doppler waveforms using fast Fourier analysis. Despite the limitations of CW Doppler techniques, they remain popular today in the assessment of patients in various clinical settings.

Pattern of ventricular septal defects and associated complications.

To determine the frequency of various types of Ventricular Septal Defect (VSD) in local population and their complications. Case series. The Paediatric Cardiac Unit of the Children Hospital and Institute of Child Health, Lahore, from January 2006 to December 2007. All patients aged between one day to 18 years presenting to the unit with isolated VSD during the study period were evaluated using 2-D, continuous wave Doppler and colour Doppler techniques on transthoracic echocardiography. Where necessary, transesophageal echocardiography and/or angiography data was used to further clarify the anatomy. Of the 854 patients with isolated VSD, 710 were of perimembranous type (83.1%), 100 were muscular type (11.7%), 25 were doubly committed subarterial (DCSA) type (2.9%) and 19 patients were having inlet VSD (2.2%). The mean age was 2.1+3 years. Females were 332 (38.8%) and males were 522 (61.1%). Aortic Valve Prolapse (AVP) was seen in 77 patients (10.8%). The mean age for this subgroup was 5.8+4 years with 54 (70.1%) males and 23 (29.9%) females. Of those, 36 (47.3%) had various degree of aortic regurgitation. Right ventricular outflow tract obstruction of variable severity was found in 4 patients. Two of these patients had echocardiographic evidence of subacute bacterial endocarditis. Perimembranous (PM) VSD is the commonest type of ventricular septal defect presenting to a tertiary care hospital. The incidence of AVP and AR is high (10.8%) and was found almost entirely in perimembranous outlet VSDs rather than DCSA. This observation has special implication in Pakistan where pool of unoperated VSDs is large.

Aortoiliac and femoropopliteal lesions in patients with concomitant peripheral arterial disease and medial arterial calcification

Objective: To characterize stenosis and/or occlusion in patients with concomitant peripheral arterial disease (PAD) and medial arterial calcifi cation (MAC). Patients and methods: We performed continuous-wave Doppler technique (to measure the ankle-brachial index - ABI) and duplex ultrasonography in 75 consecutive patients at risk for PAD (57 males, age 72.6±6.3 years) admitted to a Medical Clinic between January and March 2006. Group A was composed of 15 subjects with plaques and ABI higher than 1.3 (MAC - 20%). Normal ABI was found in 43 patients (group B - 57.33%). Group C included 17 patients with ABI lower than 0.9 (ischemia - 22.67%). Results: Nonsignifi cant aortoiliac stenosis (less than 50%) was found in 70 subjects (15 in group A, 39 in group B, and 16 in group C - nonsignifi cant). Signifi cant femoropopliteal stenosis (greater than 50%) was detected in eight patients (fi ve in group A, one in group B, and two in group C – p<0.001). Nonsignifi cant femoropopliteal stenosis was identifi ed in 54 subjects (seven in group A, 42 in group B, and fi ve in group C - p<0.001). Conclusion: Signifi cant femoropopliteal stenosis signifi cantly correlated with presence of MAC. Nonsignifi cant femoropopliteal stenosis was identifi ed in patients with normal ABI.

A New Probe for Ankle Systolic Pressure Measurement Using Photoplethysmography (PPG)

An automated method for ankle systolic pressure measurement, less operator dependent than the standard continuous wave (CW) Doppler technique, would imply an advantage both in patient measurements and in epidemiological studies. We present a new photoplethysmographic (PPG) probe that uses near-infrared light (880 nm) to detect pulsatory blood flow underneath the distal end of a standard pneumatic cuff. The probe is adapted to the anatomical conditions at the ankle, permitting recording of pressures in both ankle arteries separately. The validity of the equipment was tested with CW Doppler-derived systolic pressures and invasive blood pressure measurements for reference. In 20 healthy subjects, visual analysis of the PPG curves revealed a mean difference between CW Doppler and PPG measurements of -0.5 mmHg (SD 6.9). Corresponding results for the anterior and posterior tibial arteries separately were -1.8 mmHg (SD 6.2) and 0.9 mmHg (SD 7.3), respectively. A correct probe position was essential for the results. In direct recordings from the dorsalis pedis artery in 10 intensive care patients, PPG underestimated systolic pressure in the anterior tibial artery by 4.5 mmHg (SD 12.1). With further development, the PPG probe, integrated in the pneumatic cuff, may simplify measurements of ankle systolic pressures.

Blood flow meter apparatus and method of use

A strobed blood flow meter provides periodic measurements of blood flow velocity or volumetric blood flow over a cardiac cycle at reduced average power consumption, which is advantageous for reducing battery size, and extending device battery life, such as in an implantable application. Continuous wave Doppler, pulsed Doppler, laser Doppler, transit time, electromagnetic flow, and thermal dilution techniques are included. Strobing provides higher level excitation during active periods, which improves signal-to-noise ratio, and provides a low power standby mode during an idle time between active periods. The invention may be used for chronic or acute applications. Doppler or other signals may be telemetered from an implanted portion of the flow meter for further signal processing to extract velocity or volumetric flow. Alternatively, such signal processing is also implanted, such that the velocity signal can be telemetered to an remote monitor.

Is oscillometric ankle pressure reliable in leg vascular disease?

The objective of the study was to evaluate the validity of oscillometric systolic ankle pressure in symptomatic leg arterial occlusive disease. Ankle pressure measurements using oscillometric curves obtained using a standard 12-cm cuff with a specially designed device for signal processing were validated against the continuous wave (CW) Doppler technique. Thirty-four subjects without signs or symptoms of peripheral vascular disease (68 legs) and 47 patients with leg ischaemia (85 legs) varying from moderate claudication to critical ischaemia were examined. The oscillometric curves were analysed using several algorithms reported in the literature, based on the assumption that maximum oscillations are recorded near mean arterial pressure. In normals, reasonable agreement between CW Doppler and oscillometric methods was seen. When an algorithm that determined the lowest cuff pressure at which maximum oscillations occurred, and a characteristic ratio for systolic pressure of 0.52 was used, the mean difference between CW Doppler and oscillometry was 1.7 mmHg [range -19 to +27, limits of agreement (2 SD) 21.1 mmHg]. In ischaemic legs, oscillometry overestimated systolic ankle pressure by a mean of 28.8 mmHg [range -126 to +65, limits of agreement 82.8 mmHg]. The difference was more pronounced among patients with critical ischaemia compared with claudicants, and also more evident among diabetics. The error of oscillometric pressure determination in subjects with leg arterial disease inversely increased with CW Doppler ankle pressure. In 39% of the recordings in legs with a CW Doppler systolic pressure below 100 mmHg, the oscillometric mean arterial pressure was higher than the recorded CW Doppler systolic pressure. In conclusion, the oscillometric method to determine systolic ankle pressure, based on the concept of maximum cuff oscillations occurring near mean arterial pressure, is not reliable in leg arterial disease, usually overestimating ankle pressure.

Multiplane Transesophageal Echocardiographic Acquisition of Ascending Aortic Flow Velocities: A Comparison with Established Techniques

Acquisition of ascending aortic flow velocities with monoplane transesophageal echocardiography (TEE) have been problematic because of limitations of available imaging planes and alignment of the Doppler beam with aortic flow. The rotatable imaging array of multiplane TEE (Multi TEE) may provide improved alignment with ascending aortic blood flow. The purpose of this study was to establish the validity of maximal aortic flow velocities (VMax) and velocity time integrals (VTI) obtained by a Multi TEE continuous wave Doppler technique by comparison with those obtained by established echocardiographic techniques, suprasternal Doppler (SSD), and monoplane TEE (Mono TEE). Forty-five patients scheduled for elective surgery were prospectively studied. Multi TEE-obtained VMax and VTI were significantly greater ( P < .05), 120 ± 28.9 cm/s and 25.8 ± 7 cm, than those obtained by the SSD method, 100.2 ± 28.6 cm/s and 19.8 ± 6.8 cm, respectively. Bias analysis revealed that Multi TEE better assessed VMax (mean difference -19.7, SD of the difference of 28 cm/s) and VTI (mean difference -5.9, SD of the difference of 6.4 cm) than the SSD method. Multi TEE exhibited values for VMax 10% or greater than those obtained by SSD in 18 (48.6%) of 37 patients, and Multi TEE was 10% or greater than SSD in 23 (67%) of 37 patients for VTI determination. Values obtained by Multi TEE and Mono TEE showed close agreement. Multi TEE provides a favorable alignment for continuous wave Doppler interrogation of aortic flow and compared favorably to established techniques. This technique expands the utility of TEE to evaluate aortic valvular function and cardiac performance. (J Am Soc Echocardiogr 1999;12:754-60.)

Rates of Left Ventricular Isovolumic Pressure Rise and Fall from the Aortic Regurgitation Velocity Signal: Description of the Method and Validation in Human Beings

Background: Aortic regurgitation results from a pressure gradient across the aortic valve during left ventricular (LV) isovolumic relaxation, LV filling, and isovolumic contraction periods. Assuming the applicability of the simplified Bernoulli equation to this pressure-flow relation and constancy of aortic pressure during LV isovolumic relaxation and contraction periods, one can theoretically obtain estimates of the rates of LV isovolumic pressure fall and rise (ΔP/Δt) from the aortic regurgitation (AR) velocity signal. Methods and Results: Mitral regurgitation (MR) and AR signals were recorded by using the continuous wave Doppler technique in 26 patients with combined mitral and aortic regurgitant lesions. The LV negative ΔP/Δt was obtained by dividing the time taken for the AR velocity to rise from 1 m/sec to 2.5 m/sec into 21 mm Hg, which is the estimated LV pressure drop between these points. In a similar fashion, the LV positive ΔP/Δt was obtained between 2.5 m/sec and 1 m/sec of the fast decelerating portion of the AR signal. The LV negative ΔP/Δt by the AR method ranged from 420 to 3500 mm Hg/sec and correlated well with that obtained by the MR method obtained in a blinded fashion ( r = 0.95, p < 0.0001). The mean (SD) difference between the two methods was 30 (129) mm Hg/sec. Similarly, the LV positive ΔP/Δt by the AR method (range 420 to 2625 mm Hg/sec) correlated closely with that obtained by the MR method ( r = 0.93, p < 0.0001), with the mean (SD) difference between the two methods being 38 (138) mm Hg/sec. Conclusions: Preliminary data presented in this study indicate the feasibility of obtaining a reliable estimate of LV positive and negative ΔP/Δt from the AR velocity profile. Thus the examination of the AR signal may give valuable insights into both LV systolic and diastolic functions. (J Am Soc Echocardiogr 1998;11:631-7.)

Neonatal tricuspid insufficiency—a Doppler echocardiographic study of 49 cases

SummaryWe analyzed tricuspid insufficiency noninvasively using cross-sectional and continuous wave Doppler echocardiography in 49 newborn infants free of structural cardiac and pulmonary disease. In 41(83.6%) of the cases, mild insufficiency was detected using the continuous wave Doppler technique. All the infants with valvar insufficiency had normal electrocardiographic tracings and, in 25 (61%) of them, there was no audible murmur. We detected transient ductal patency in five (12.1%). The ratio of right ventricular preejection period to ventricular ejection time was in the normal ranges (below 0.05) in 39 (95.1%) of the neonates. Of the 30 cases who underwent continued surveillance over a mean period of 37.9 days, the incompetence disappeared in 15 (50%). Our findings show that, in neonates, the lack of a murmur does not eliminate the possibility of neonatal tricuspid incompetence. Furthermore, abnormalities such as postnatal transient pulmonary hypertension, fetal closure of the arterial duct and perinatal asphyxia cannot readily explain the finding of tricuspid incompetence.

Effect of stenosis geometry on the Doppler-catheter gradient relation in vitro: A manifestation of pressure recovery

Objectives. This study investigated the effect of stenosis geometry on the Doppler-catheter gradient relation.Background. Although gradient estimation by Doppler ultrasound has been shown to be accurate in various clinical and in vitro settings, there have also been reports of substantial discrepancies between Doppler and catheter gradients. These conflicting results may be due to differences in geometry and hemodynamic characteristics of flow obstructions.Methods. Stenoses of various geometry were simultaneously studied with continuous wave Doppler and catheter technique in a well controlled pulsatile flow model.Results. Doppler and catheter gradients correlated very well regardless of stenosis geometry and site of distal catheter measurement (r = 0.98 to 0.99, SEE = 1.8 to 5.3 mm Hg). When the catheter was pulled back through the stenosis, the highest gradients were found in or close to the stenosis. When these catheter gradients were compared with Doppler gradients, the agreement between the two techniques was excellent regardless of stenosis geometry (slope 0.97; mean difference 0.6 ± 2.0 mm Hg). However, when distal pressures were measured 10 cm downstream from the stenotic segment, the slope of the regression line, and therefore the agreement between Doppler and catheter gradients, differed for the different stenosis types (slopes from 0.98 to 1.69). In stenoses with abrupt narrowing and abrupt expansion, agreement was acceptable. Doppler gradients were only slightly greater than catheter gradients (mean difference 4.5 ± 5.2 mm Hg). In stenoses with a gradually tapering inlet and outlet, the Doppler-catheter gradient relation was dependent on the outflow angle. Good agreement was found for an angle of 60 ° (mean difference 0.6 ± 1.8 mm Hg). In stenoses with a 40 ° outflow angle, Doppler gradients exceeded the catheter gradients by 13% on average; for stenoses with a 20 ° outflow angle, Doppler gradients exceeded catheter gradients by 46 ± 11.4%, with differences as great as 65 mm Hg. These results were identical for stenoses gradually tapering outward to the distal tubing diameter and those with abrupt expansion after 2 cm of gradual expansion. The results were also not affected by changing the inflow angle from 20 ° to 60 °. However, an abrupt narrowing instead of a tapering inlet significantly altered the Doppler-catheter gradient relation (p < 0.001); Doppler gradients exceeded the catheter gradients by 34 ± 10% for this stenosis type.Conclusions. Doppler gradients accurately reflect the highest gradients across flow obstructions that occur in the vena contracta. However, these gradients may be significantly greater than catheter gradients that are measured farther downstream, as is usually the case in clinical catheterization studies. These discrepancies are due to pressure recovery. The magnitude of pressure recovery is highly dependent on the stenosis geometry, which therefore significantly affects the Doppler-catheter gradient relation. It is the outflow geometry that predominantly influences this relation, but the shape of the inlet may affect the results as well. Although pressure recovery occurs even in stenoses with abrupt narrowing and abrupt expansion, the phenomenon is most likely to become clinically relevant in stenoses with a gradually tapering inlet and outlet with an outflow angle ≥20 °.

Cerebral blood flow velocity and failure of autoregulation in neonates: their relation to outcome of birth asphyxia.

Using the continuous wave Doppler technique, we examined the pulsatility index (PI) of the anterior cerebral artery in 14 asphyxiated infants. We also measured the blood pressure (BP) and fontanel pressure (FP) and calculated the cerebral perfusion pressure (CPP). According to the neurological prognosis, we divided the 14 infants into two groups and studied correlation of each factor. In the good-prognosis group (n = 11), PIs are within normal limits. There is a negative correlation between BP, CPP and PI, suggesting that the autoregulation of cerebral blood flow has been lost. On the other hand, there is no significant correlation between BP, CPP and PI in the poor-prognosis group (n = 3). These infants are thought to have lost the autoregulation, but their cerebral blood flow is not pressure-passive. Not only BP but also brain edema, vasodilation, and possibly other factors may contribute to determine the cerebral blood flow. Concerning FP, no remarkable correlations are found between two groups. It is therefore very important to monitor the PI, BP, FP in asphyxiated infants even if the degree of asphyxia is mild.

Clinical application of transpulmonary contrast-enhanced Doppler technique in the assessment of severity of aortic stenosis

Objective. The aim of this study was to demonstrate the clinical usefulness of the transpulmonary contrast-enhanced Doppler technique by using it to assess the severity of aortic stenosis.Background. Sonicated albumin microbubbles can pass through the pulmonary circulation after peripheral venous injection and have been reported to enhance Doppler signals from the left side of the heart. Therefore, their use to determine aortic flow velocity would facilitate the assessment of the severity of aortic stenosis.Methods. Twenty-two patients with aortic stenosis and seven normal volunteers were examined. Aortic now velocity was recorded with continuous wave Doppler technique from an apical window before and after injection of 2 ml of sonicated albumin.Results. In 10 patients with aortic stenosis, the aortic velocity envelop was too indistinct to determine the peak velocity before sonicated albumin was injected. After injection, the aortic flow Doppler signal was enhanced in 9 of the 10 patients and the velocity envelop became clear enough to measure the peak velocity, enabling calculation of the transaortic pressure gradient. In the remaining 12 patients with aortic stenosis and in all 7 normal volunteers, the velocity envelope was dear before injection and became much clearer after injection. The calculated transaortic pressure gradient showed a good agreement with catheterization measurements (y = 1.1x-6.5, r = 0.88. p < 0.001, SEE = 16 mm Hg, n = 13). Duration of Doppler signal enhancement was measured as the time during which the envelope was clearer than before injection throughout the ejection period. The duration was significantly shorter in patients with aortic stenosis than in normal volunteers (16 ± 5 vs. 52 ± 32 s, p < 0.01).There was a significant correlation between left ventricular systolic pressure measured by catheterization and the duration of signal enhancement (r = -0.69), suggesting that albumin microbubbles were fragile at high pressure.Conclusions. The transpulmonary contrast-enchanced Doppler technique using sonicated albumin is useful for assessing the severity of aortic stenosis even in patients with poor Doppler recordings, although, the duration of signal enhancement might be affected by left ventricular systolic pressure.

Value of a modified continuity equation method to quantify mitral valve area in patients with mitral stenosis and sinus rhythm

To quantify valve area in mitral stenosis, a modified continuity equation method using continuous wave Doppler and thermodilution measurements was applied. In 14 patients with mitral stenosis and sinus rhythm (age: 49 +/- 11 years), transmitral flow velocity was recorded by continuous wave Doppler during right and left heart catheterization. Mitral valve area was calculated by three different methods: 1. According to the continuity equation, stroke volume (thermodilution technique) was divided by the registered time velocity integral of the mitral stenotic jet (continuous wave Doppler). 2. Mitral valve area was calculated by the pressure half-time method. 3. Simultaneous pulmonary capillary wedge and left ventricular pressure measurements were used for determination of mitral valve area according to the Gorlin formula. The mitral valve area determined by application of the continuity equation (y) showed a close correlation to the valve area calculated by the Gorlin equation (x): y = 0.73x + 0.12, SEE = 0.11 cm2, r = 0.88, P less than 0.001. In contrast, the correlation between mitral valve area determined by pressure half-time (y) and the Gorlin formula (x) was not as good: y = 0.77x + 0.11, SEE = 0.26 cm2, r = 0.65, P less than 0.05. Thus, the continuity equation method using combined continuous wave Doppler and thermodilution technique allows a valid determination of mitral valve area. In patients with mitral stenosis and sinus rhythm, this technique is superior to the noninvasive determination of mitral valve area by the conventional pressure half-time method.

Effect of Postural Stress on Left Ventricular Performance Using the Continuous-Wave Doppler Technique

To evaluate the effect of postural shifts on continuous-wave Doppler indices of left ventricular performance in normal man, we recorded Doppler signals suprasternally in 69 healthy volunteers, ranging in age from 20 to 86 years, in the supine position and 2 min after assumption of sitting and standing postures. All indices decreased progressively with increasing orthostasis: peak acceleration (PKA): 15.6 +/- 4.5 m/s2 to 14.0 +/- 4.0 m/s2 to 13.6 +/- 4.6 m/s2; peak velocity (PKV): 0.64 +/- 0.18 m/s to 0.58 +/- 0.17 m/s to 0.56 +/- 0.17 m/s; stroke distance (SD): 11.4 +/- 3.7 cm to 9.8 +/- 3.4 cm to 8.0 +/- 2.8 cm; SD x heart rate (VIH): 717 +/- 272 cm to 655 +/- 268 cm to 572 +/- 217 cm, from supine to sitting to standing, respectively (p less than 0.001). In contrast heart rate increased modestly from 62.4 +/- 10.0 bpm supine, to 66.9 +/- 12.4 bpm sitting, to 71.3 +/- 9.9 bpm standing (p less than .001). Similar postural changes in Doppler variables were seen in all three age groups (20 to 44 years; 45 to 64 years; and 65 to 86 years). Thus, orthostasis in normal subjects is accompanied by a reduction in all continuous-wave Doppler indices of left ventricular performance, regardless of age.

Measurement of aortic blood flow by doppler echocardiography: Day to day variability in normal subjects and applicability in clinical research

To assess the reliability of Doppler ultrasound for detecting serial changes in cardiac output in response to experimental interventions, the day to day variability of the minute distance of aortic flow was determined in seven normal subjects maintained in a tightly controlled environment with regard to diet and activities. Measurements were made at the same time on 5 to 6 sequential days from an apical window with use of both continuous wave and pulsed wave Doppler techniques. Two statistical measures of reliability were calculated, the intraclass coefficient of correlation (R), which varies between 0 (null reliability) and +1 (perfect reliability), and the 95% confidence interval for the error-free value of a single measurement. For sequential measurements of arterial pressure, 24 h urinary volume and sodium excretion and body weight, the intraclass coefficients of correlation ranged from 0.85 to 0.99, indicating low day to day variability consistent with tight environmental control. Continuous and pulsed wave modes were proved equally and highly reliable for measuring minute distance of aortic flow. However, continuous wave Doppler ultrasound provided acceptable signals more frequently than did the pulsed wave technique. For continuous wave Doppler ultrasound, R was 0.87 (p less than 0.00001); the 95% confidence interval was +/- 1.81 m/min (or 11% of the mean of all measurements), which indicates that this method can be used in a single individual to detect a greater than 11% change in minute distance measured once before and after an intervention.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of Valvular Regurgitation by Doppler Echocardiography

Although most clinical decisions about timing of intervention remain based on symptoms or evidence of progressive ventricular dysfunction in valvular regurgitation, several available Doppler techniques can give confirmation of the presence of significant insufficiency. For these reasons, the 2D echocardiographic and Doppler evaluation has become an integral part of the diagnostic and clinical management of these patients. These imaging techniques are still in their infancy, however, and the exact relationship between jet appearance and clinical and hemodynamic implications remains to be defined. Newer approaches to color flow display of Doppler velocity information, such as power mode, quantification of jet momentum, and kinetic energy mapping may provide a better understanding of the dynamic nature of valvular regurgitation. In the future, Doppler recordings may provide the basis for a more sophisticated understanding of the hydrodynamics of valve dysfunction.

Dynamic changes in left ventricular outflow tract flow velocities after amyl nitrite inhalation in hypertrophic cardiomyopathy

Doppler echocardiography was performed in 21 patients with hypertrophic cardiomyopathy (HC), in nine patients with no evidence of left ventricular (LV) hypertrophy by two-dimensional echocardiography, and in five patients with systemic hypertension and concentric LV hypertrophy. The LV outflow tract (LVOT) peak velocity was recorded by continuous wave Doppler technique at rest and after amyl nitrite inhalation. The LVOT pressure gradient was calculated by the modified Bernoulli equation. A significant increase in heart rate and a drop in systolic blood pressure were observed in all patients after amyl nitrite inhalation; no adverse effects were encountered. The peak LVOT velocity and pressure gradient increased significantly after provocation in all patients, but the increase was much more pronounced in patients with HC (peak LVOT velocity increased from 2.2 ± 0.8 to 4.3 ± 1.0 m/sec and peak gradient increased from 22 ± 17 to 78 ± 36 mm Hg). The Doppler spectral signal in patients with HC demonstrated a characteristic contour, with peak velocity occurring in late systole. However, the observed increase in LVOT peak velocity was not statistically different between treated (with β-blockers and calcium blockers) and untreated patients with HC. We conclude that LVOT peak velocity and pressure gradients in patients with HC can be readily assessed by Doppler echocardiography both at rest and after amyl nitrite inhalation. The dynamic changes in LVOT velocity induced by this provocation have certain characteristic features in obstructive HC but appear to be independent of the medical regimen used, at least in the dosages tested in our study.