Bidirectional ductal shunts in the early neonatal period: evaluation by Doppler color flow imaging

Serial Doppler echocardiographic examinations were performed in 10 normal neonates (0.3-4.0 hrs after birth). The flow patterns through the ductus arteriosus were evaluated using Doppler color flow imaging, pulsed Doppler echocardiography and continuous-wave Doppler echocardiography. At the initial examination, flow through the ductus arteriosus was clearly visualized in all the neonates using Doppler color flow imaging. The ductal flow patterns were categorized as follows: 1. Systolic blue color (right-to-left shunt flow) and diastolic red color (left-to-right shunt flow) in four neonates (group 1). 2. Systolic blue color and diastolic mosaic colors in four neonates (group 2). 3. Continuous mosaic colors in two neonates (group 3). Using pulsed Doppler echocardiography, the systolic right-to-left ductal shunt flow in the groups 1 and 2 was triangular in shape beginning in early systole. The diastolic left-to-right shunt flow was box-like in shape beginning late in systole and lasting long in diastole in the group 1. In the group 2, the diastolic flow showed a wide spectrum (turbulent flow). In the group 3, the flow through the ductus arteriosus had a continuous wide spectrum (turbulent flow). Mosaic or turbulent ductal flow of a left-to-right ductal shunt had high velocities by continuous-wave Doppler echocardiography. Serial examinations revealed that the ductal flow pattern observed in the group 1 changed to the flow pattern observed in the group 2, and then to that of the group 3 with increasing diastolic ductal flow velocities. The estimated aorto-pulmonary pressure gradient according to the simplified Bernoulli equation (delta p = 4V2) using a maximum diastolic left-to-right ductal shunt velocity increased within 12 hrs after birth. It was concluded that bidirectional ductal shunts may be observed in most normal neonates (8/10). With increasing diastolic velocities the bidirectional ductal flows changed to the pattern of a continuous left-to-right shunt. The bidirectional ductal shunt is considered due to physiologic pulmonary hypertension of the newborn and due to less conduction time from the pulmonary valve to the pulmonary end of the ductus than from the aortic valve to the aortic end of the ductus. Analysis of the flow through the ductus provides informations about the neonatal circulatory adaptation, especially in the early neonatal period.     

Noninvasive Doppler echocardiographic evaluation of shunt flow dynamics of the ductus arteriosus

The pulsed Doppler technique was used to record the flow velocity patterns in the ductus arteriosus and the pulmonary artery in 26 patients with either isolated or complicated patent ductus arteriosus (PDA). In all patients, abnormal Doppler signals indicating left-to-right (L-R) or right-to-left shunt flow or both could be obtained at the site of the ductus arteriosus. These Doppler flow patterns determined within the ductus coincided with the direction of ductal flow seen on the contrast two-dimensional echocardiogram. No Doppler signals of shunt flow were demonstrated in any of 42 control subjects. The peak, mean, and diastolic velocities of the L-R shunt flow within the ductus were measured from the ductal flow velocity profiles. With the Doppler-derived measurements of the mean and diastolic velocities, patients with normal pulmonary arterial pressure and those with evidence of pulmonary hypertension could be correctly identified. In addition, the mean velocity of the diastolic antegrade flow portion obtained from the proximal left pulmonary artery, which was related to ductal L-R shunting, was measured in 16 patients with isolated PDA. This Doppler flow determinant showed a good linear correlation with the L-R shunt ratio determined by Fick's method (r = .88, p less than .01). Our technique permits the noninvasive evaluation of shunt flow dynamics in patients with PDA.     

Comparison of coronary flow velocities between patients with obstructive and nonobstructive type hypertrophic cardiomyopathy: noninvasive assessment by transthoracic Doppler echocardiography

BACKGROUND: We aimed to compare coronary flow velocity (CFV) measurements of patients with nonobstructive (NHCM) and obstructive hypertrophic cardiomyopathy (HOCM) by using transthoracic Doppler echocardiography (TTDE). METHODS AND RESULTS: In 11 patients with NHCM and 26 with HOCM, CFV in the distal left anterior descending (LAD) coronary was measured by TTDE (3.5 MHz) under the guidance of color Doppler flow mapping in addition to standard 2D and Doppler echocardiography. The results were compared with 24 normal participants who had no evidence of cardiac disease. Peak diastolic velocity of LAD was also higher in NHCM and HOCM than controls (52 +/- 14 cm/sec and 54 +/- 20 cm/sec vs 41 +/- 11 cm/sec, respectively, P < 0.01). The analysis of systolic velocities revealed abnormal flow patterns in 16 (61%) patients with HOCM (12 systolic-reversal flow and 4 no systolic flow) and 6 (54%) (5 reversal flow and 1 zero flow) patients with NHCM (-11 +/- 30 cm/sec and -13 +/- 38 cm/sec, vs 24 +/- 9 cm/sec, respectively, P < 0.001). Linear regression analysis demonstrated no correlation between intraventricular pressure gradient and coronary flow velocities in HOCM patients. However, there were significant positive and negative correlations between septal thickness and diastolic and systolic velocities, respectively (r = 0.50, P < 0.002, and r =-0.43, P < 0.005). CONCLUSION: We conclude that the coronary flow velocity abnormalities are independent from the type of hypertrophic cardiomyopathy.     

Changes in pulmonary venous flow pattern during early neonatal life.

OBJECTIVE--To investigate serial changes in the pattern of flow in the pulmonary vein during the early neonatal period. METHODS--Pulsed Doppler echocardiography was used to measure flow in the right upper pulmonary vein in 26 normal newborn infants. Peak flow velocity during systole (S) and diastole (D) and flow velocity at indents between the systolic and diastolic fraction (O) and between the diastolic and systolic fraction (X) were measured 1, 4-8, 24, and 96 hours after birth. The heart rate and diameter of the ductus arteriosus were measured simultaneously. RESULTS--Continuous and phasic high flow velocity waveforms were seen 1 and 4-8 hours after birth. The mean (SD) peak flow velocities of X, S, O, and D an hour after birth were 35.2 (13.6) cm/s, 73.1 (23.1) cm/s, 58.5 (20.5) cm/s, and 81.5 (19.2) cm/s respectively. There were significant decreases in X, S, O, and D by 24 hours of age (p < 0.01 v 1 hour after birth) to 8.1 (10.3) cm/s, 52.8 (18.0) cm/s, 38.6 (14.5) cm/s, and 54.4 (11.2) cm/s respectively. These results indicate intermittent flow in the pulmonary vein, with flow stopping between diastole and systole. These flow velocities, X, S, O, and D, correlated well with the diameter of the ductus arteriosus (r = 0.80 v X, r = 0.62 v S, r = 0.63 v O, r = 0.75 v D). CONCLUSION--This serial study showed changes in normal pulmonary vein flow patterns during the early neonatal period. The continuous and high flow velocity waveform that was seen immediately after birth resembled the pattern of pulmonary vein flow seen in congenital pulmonary stenosis and in cases of acute volume overload. This waveform may reflect a sudden increase in pulmonary circulatory volume with additional left to right shunting through the ductus arteriosus in relatively hypoplastic pulmonary veins.     

The newborn transitional circulation: a two-dimensional Doppler echocardiographic study

To characterize changes in circulation after birth, 11 normal full-term infants were examined with two-dimensional and pulsed Doppler echocardiography. The initial examination was performed within 10 hours after delivery and serially for 3 days. Retrograde diastolic pulmonary artery velocities, which are evidence for a patent ductus arteriosus, were detected in 10 infants (91%) on day 1, in 2 (18%) on day 2 and in none on day 3. Retrograde systolic descending aortic velocities, which are evidence of flow from the aorta into the ductus arteriosus, were observed in 10 infants (91%) on day 1, 9 (81%) on day 2 and 7 (64%) on day 3. Persistence of the retrograde systolic velocity in the descending aorta in the absence of retrograde diastolic velocity in the pulmonary artery is consistent with physiologic ductal closure beginning near the pulmonary artery end of the ductus arteriosus. Localized turbulent retrograde systolic flow, proximal to the septal leaflet of the tricuspid valve and consistent with tricuspid insufficiency, was detected in six patients (55%) on day 1, in eight (73%) on day 2 and in seven (64%) on day 3. Thus, tricuspid insufficiency appears to be a frequent observation in healthy newborns. Normal Doppler velocities in the great arteries and across the tricuspid and mitral valves of newborns up to 3 days of age are presented. These normal measures of intracardiac flow velocities may be used for comparison to identify abnormal flow profiles in newborns with congenital heart defects.     

The ductus arteriosus in healthy newborn infants studied by continuous Doppler guided by two-dimensional Doppler color echocardiography

To characterize the ductus arteriosus shunt after birth, 53 normal newborn infants (36-41 weeks gestation), appropriate in size for gestational age, were examined using two dimensional Doppler echocardiography directed continuous Doppler for evidence of patent ductus arteriosus. The infants were examined within six hours of birth, and every six-eight hours thereafter until ductus arteriosus shunt could no longer be detected. In 51/53 infants, an adequate examination was possible and ductus arteriosus was detected in every infant using the standard precordial approach. Using two dimensional Doppler echocardiography a yellow-orange-red jet, sometimes blue in the central area, directed at the lateral wall of the pulmonary artery was recorded; using continuous Doppler a diastolic or continuous spectral flow into the main pulmonary artery was recorded. Ductus arteriosus shunt could no longer be detected in 7 infants 12 hours after birth, in 26 infants 12-24 hours after birth, in 11 infants 24-36 hours after birth, in 5 infants 36-48 hours after birth and in 2 infants 48-60 hours after birth. A diastolic spectral Doppler flow was present in 38 infants and became continuous before duct closure in 27 infants. In 13 infants it was continuous at first examination and until the ductus arteriosus closure. Both diastolic or continuous spectral Doppler flow could present a flat waveform profile, or a protodiastolic or protosystolic peak velocity. The shunt peak velocity increased significantly with the age i.e. (1.5 +/- 0.7 m/sec mean and SD-), at first examination, vs 2.3 +/- 0.6 m/sec at last examination before ductus arteriosus closure (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical Features of the Complete Closure of the Ductus Arteriosus Prenatally

Objective. Prenatal constriction of the ductus arteriosus associated with maternal drug ingestion was reported several decades ago. There are fewer reports of the complete closure of the ductus arteriosus; therefore, the clinical features of the latter are poorly understood. The aim of this study is to clarify the clinical features of complete ductal closure and postnatal pulmonary hypertension by performing echocardiography of the fetus. Patients. We diagnosed four fetuses with complete ductal closure by performing fetal echocardiography and reviewed the prenatal and postnatal medical records of the mother and fetus. Results. One mother each had bronchial asthma, ulcerative colitis, and idiopathic thrombocytopenic purpura, and they had received nonsteroidal anti‐inflammatory drugs and/or corticosteroids during pregnancy. The fourth mother did not have basal disease and had not ingested any drugs. Fetal diagnosis was performed at 32–38 weeks of gestation. All fetuses had right heart dilatation with tricuspid regurgitation in the absence of any cardiac defects, and Doppler echocardiography indicated that the right ventricular pressure was elevated. Two of the fetuses had fetal hydrops, which suggested severe right heart dysfunction. All fetuses were delivered by emergent cesarean delivery. After birth, all the infants developed persistent pulmonary hypertension and required oxygen inhalation. Of these, three required mechanical ventilation, and two, nitric oxide inhalation. All infants improved within 2 weeks, and they had no neurological and cardiac complications after discharge. Conclusion. Right heart dilatation and severe tricuspid regurgitation in the absence of a cardiac defect in the fetus strongly suggested ductal dysfunction. Careful evaluation of ductal patency and right ventricular function can lead to precise early diagnosis and good prognosis.     

Intracardiac blood flow velocities and cardiac output in normal fetuses: a prospective pulsed Doppler echocardiographic study.

Two dimensional and pulsed Doppler echocardiographic studies were performed in human fetuses with the aim to establish normal values for blood flow velocities and cardiac output in Indian subjects. Thirteen pregnant mothers were prospectively followed up at 4 weeks interval from 19 to 40 weeks of gestation. Blood flow velocity spectra across aortic, pulmonary, mitral and tricuspid valves were analyzed to obtain peak flow velocity (cm/sec) and velocity time integral. Aortic and pulmonary diameters were measured at the valve level from two dimensional echocardiographic images and ventricular stroke volume calculated. The values were plotted against fetal age (weeks) and fetal weight (gms). Our results showed that there is a linear increase of the measured Doppler data, with increasing gestational age and weight. These values may be used as a reference for the Indian population.     

Cardiac Doppler flow velocities in human fetuses

Cardiac Doppler flow velocity studies were performed in normal human fetuses between 18 and 40 weeks of gestation. Two-dimensional linear array and sector scanning techniques were used for the initial evaluation of the fetuses, which included a standard ultrasound examination to determine normal anatomy and estimated gestational age and weight. Fetal cardiac ultrasound examination was then performed, with four-chamber, short-axis/great vessel, long-axis/left ventricular outflow tract, and aortic arch views obtained. Pulsed echo Doppler instrumentation was used to obtain flow velocity measurements through the tricuspid, pulmonary outflow, mitral, and aortic outflow regions. Calculation of transvalve volume flow for mitral and tricuspid valves was performed by combining the valve anulus sizes and calculated mean temporal velocities for the valves. Maximal flow velocities were greater through the tricuspid (mean maximal velocity 51 +/- 1.2 [SE] cm/sec) than through the mitral (47 +/- 1.1 cm/sec; p less than .05) valve regions, with a wide range of scatter for results between fetuses but less than 6% average variation in the individual fetuses during gestation. For 18 fetuses, right heart dimensions and volume flows (mean 307 + 30 ml/kg/min) were greater than left heart dimensions and volume flows (232 +/- 25 ml/kg/min). Doppler echocardiography may prove to be useful as an adjunct to imaging echocardiography for evaluation of fetal cardiac anatomy and function.     

Doppler echocardiographic estimates of pressure gradients in various types of stenoses: usefulness and limitations

In the present study, the accuracy of Doppler estimates of pressure gradients in various types of stenoses was clinically and experimentally evaluated. Fifty-seven patients, including 23 with ventricular septal defect, 15 with aortic or pulmonary valvular stenosis, four with infundibular stenosis, and five with supravalvular aortic or pulmonary stenosis were observed. The peak systolic pressure gradient (dP (C] was obtained at the time of catheterization in all patients. Before catheterization, the maximum velocity was measured by pulsed or continuous Doppler echocardiography and the estimated systolic pressure gradient according to Doppler (dP (D] was calculated by the simplified Bernoulli equation. The experimental model was designed to create pulsatile flow through a stenosis model. Nine different stenotic model types were used, including three orifice-like stenoses and six truncated cones with heights of 10 mm and 20 mm distal to the stenosis. The orifices in their stenoses were 3, 4 and 5 mm, respectively. Glycerin solution containing Sephadex with a viscosity similar to that of blood was used as the circulation medium. Its specific gravity was 1.16 g/cm3. In each stenotic model, the maximum velocity and instantaneous systolic peak pressure gradient were measured at various water flow rates. Clinical results: In patients with ventricular septal defect or valvular stenosis, dP (D) correlated very well to dP (C), with the regression equation, y = 0.87x + 2.79 (r = 0.92) or y = 0.96x + 1.02 (r = 0.99). In the other patients except for three with patent ductus arteriosus, dP (D) overestimated dP (C) by 11 to 71 mmHg, and their post-stenotic areas had gradually widened according to angiographic findings.(ABSTRACT TRUNCATED AT 250 WORDS)     

Pulmonary Venous Flow and Correlates in Patients with Aortic Stenosis

In order to determine the value of pulmonary venous flow (PVF) pulsed Doppler measurements in assessing filling pressures in aortic stenosis (AS), we studied 20 patients by transthoracic and transesophageal echocardiography and catheter examination. Peak systolic PVF correlated with pulmonary capillary wedge pressure (PCWP) (r =-0.67, P < 0.01), the ratio of peak systolic to diastolic PVF correlated with PCWP (r =-0.68, P < 0.01) and left ventricular end-diastolic pressure (r =-0.51, P < 0.01). Peak systolic PVF < 40 cm / sec was highly sensitive and specific in the detection of PCWP ≥ 15 mmHg (100% and 84%, respectively). Correlations between PVF and pulsed Doppler transmitral indices were also found (r = 0.66 between peak systolic to diastolic PVF and peak late transmitral velocity, P < 0.01); however, PVF indices predicted filling pressures better than Doppler transmitral indices. In conclusion PVF indices are accurate predictors of high filling pressures in AS patients.     

Left Atrial Systolic Performance in the Presence of Elevated Left Ventricular End-Diastolic Pressure: Evaluation by Transesophageal Pulsed Doppler Echocardiography of Left Ventricular Inflow and Pulmonary Venous Flow Velocities

We recorded left ventricular inflow (LVIF) and pulmonary venous flow (PVF) velocities by transesophageal pulsed Doppler echocardiography in 25 patients with a ratio of peak atrial systolic to early diastolic LVIF velocity of <1 and a left ventricular end-diastolic pressure (LVEDP) of 15 mmHg or greater, as well as in 30 normal subjects. The group consisted of 14 patients with prior myocardial infarction, 7 with dilated cardiomyopathy, and 4 with cardiac amyloidosis, and were divided into: (1) group A (n = 7): peak atrial systolic LVIF velocity of 40 cm/sec or greater; (2) group B (n = 7): peak atrial systolic LVIF velocity of <40 cm/sec and peak atrial systolic PVF velocity of 30 cm/sec or greater; and (3) group C (n = 11): peak atrial systolic LVIF velocity of <40 cm/sec and peak atrial systolic PVF velocity of <30 cm/sec. Although LVEDPs in groups B and C were significantly greater than in group A, there was no difference between groups B and C. The mean pulmonary capillary wedge pressure (mPCWP) in group C was significantly greater than in groups A and B, but there was no difference between groups A and B. The difference between LVEDP and mPCWP (LVEDP - mPCWP) in group B was significantly higher than in groups A and C. Dilatation of the left atrium (LA) was seen in all three groups, particularly in groups B and C. There were no differences in peak atrial systolic LVIF velocity and LA volume change during atrial contraction between group A and the control group, and there were no differences in LA volume change and peak second systolic PVF velocity between groups A and B. LA volume change and peak second systolic PVF velocity were significantly less in group C than in groups A and B. Among the four patients whose courses could be observed after medical treatment with diuretic and vasodilator, one changed from group B to A, one from group B to C, one from group C to A, and one remained in group C. Thus, recording of peak atrial systolic LVIF and PVF by transesophageal pulsed Doppler echocardiography permits detailed evaluation of LA systolic performance in the presence of elevated LVEDP. These two variables provide important information for less invasive differentiation of LA afterload mismatch from LA myocardial failure.     

Validation of a Doppler echocardiographic method for calculating severity of discrete stenotic obstructions in a canine preparation with a pulmonary arterial band

The purpose of this study was to develop an open-chest animal preparation to validate the accuracy of a two-dimensional Doppler echocardiographic method for estimating pressure drops across discrete stenotic obstructions. Six mongrel dogs underwent median sternotomy and catheters were placed in the right ventricle, distal main pulmonary artery, and aorta of each. A 1/8 inch umbilical tape was sewn to the posterior rim of the pulmonary artery just above the anulus and was progressively tightened to vary the degree of stenosis. Ultrasound and Doppler studies were performed with a 2.5 MHz phased-array unit with capabilities for pulsed or continuous-mode Doppler and real-time imaging. Peak systolic main pulmonary arterial flow velocities were recorded by Doppler echocardiography within the jet distal to the band from an oblique parasternal short-axis echocardiographic view and corrected for angle of incidence between the direction of Doppler sampling and the presumed direction of flow. Doppler velocities were converted to gradients with a simplification of the Bernoulli equation (gradient = 4 X maximal Doppler flow velocity2 ). Maximal Doppler-determined systolic pulmonary arterial velocities showed a good linear correlation with the 63 measured pressure drops (r = .95, SEE +/- 36.3 cm/sec). An excellent correlation was also found between Doppler-calculated and actual pressure gradients (r = .96, SEE +/- 7.26 mm Hg). Our results suggest that this Doppler method for measuring gradients across discrete stenotic obstructions may be quite accurate in clinical applications.     

Doppler echocardiography of fetal ductus arteriosus constriction versus increased right ventricular output

A prospective longitudinal study from 121 examinations of 41 normal pregnant women showed that fetal ductal flow velocities increased with gestational age. These normal data were compared with data in three groups of fetuses with altered ductal flow velocities: 22 fetuses (mean gestational age 31.3 weeks) had ductal constriction due to maternal indomethacin treatment; 10 fetuses (mean gestational age 27.9 weeks) had been exposed to terbutaline, a positive inotropic agent and 14 fetuses (mean gestational age 33.3 weeks) had hypoplastic left heart syndrome. In normal fetuses maximal systolic, mean and end-diastolic ductal flow velocities increased linearly (p less than 0.0001). The pulsatility index did not change (mean +/- 2 SD: 2.46 +/- 0.52). Fetuses with ductal constriction had higher maximal, mean and end-diastolic flow velocities and a significantly lower pulsatility index than did normal fetuses (1.25 +/- 0.76; p less than 0.0005). Six of 10 fetuses of the terbutaline group and 8 of 14 fetuses with hypoplastic left heart syndrome had increased maximal flow velocity, but normal or only mildly elevated mean flow velocity. The pulsatility index in fetuses during terbutaline therapy and with hypoplastic left heart syndrome was significantly higher than in normal fetuses (3.11 +/- 0.46 and 3.09 +/- 0.7, respectively, vs. 2.46 +/- 0.52; p less than 0.0005). Fetal ductal waveform analysis was necessary to distinguish fetal ductal constriction from increased right ventricular output. These measurements may be helpful in the diagnosis of left-sided outflow obstruction and assessment of fetal hemodynamic data.     

Relation between symptoms and profiles of coronary artery blood flow velocities in patients with aortic valve stenosis: a study using transoesophageal Doppler echocardiography.

OBJECTIVE: To analyse profiles of coronary artery flow velocity at rest in patients with aortic stenosis and to determine whether changes of the coronary artery flow velocities are related to symptoms in patients with aortic stenosis. DESIGN: A prospective study investigating the significance of aortic valve area, pressure gradient across the aortic valve, systolic left ventricular wall stress index, ejection fraction, and left ventricular mass index in the coronary flow velocity profile of aortic stenosis; and comparing flow velocity profiles between symptomatic and asymptomatic patients with aortic stenosis using transoesophageal Doppler echocardiography to obtain coronary artery flow velocities of the left anterior descending coronary artery. SETTING: Tertiary referral cardiac centre. PATIENTS: Fifty eight patients with aortic stenosis and 15 controls with normal coronary arteries. RESULTS: Adequate recordings of the profile of coronary artery flow velocities were obtained in 46 patients (79%). Left ventricular wall stress was the only significant haemodynamic variable for determining peak systolic velocity (r = -0.83, F = 88.5, P < 0.001). The pressure gradient across the aortic valve was the only contributor for explaining peak diastolic velocity (r = 0.56, F = 20.9, P < 0.001). Controls and asymptomatic patients with aortic stenosis (n = 12) did not differ for peak systolic velocity [32.8 (SEM 9.7) v 27.0 (8.7) cm/s, NS] and peak diastolic velocity [58.3 (18.7) v 61.9 (13.5) cm/s, NS]. In contrast, patients with angina (n = 12) or syncope (n = 8) had lower peak systolic velocities and higher peak diastolic velocities than asymptomatic patients (P < 0.01). Peak systolic and diastolic velocities were -7.7 (22.5) cm/s and 81.7 (17.6) cm/s for patients with angina, and -19.5 (22.3) cm/s and 94.0 (20.9) cm/s for patients with syncope. Asymptomatic patients and patients with dyspnoea (n = 14) did not differ. CONCLUSIONS: Increased pressure gradient across the aortic valve and enhanced systolic wall stress result in characteristic changes of the profile of coronary flow velocities in patients with aortic stenosis. Decreased or reversed systolic flow velocities are compensated by enhanced diastolic flow velocities, particularly in patients with angina and syncope. This characteristic pattern of the profile of coronary artery flow velocities in patients with angina or syncope may be useful for differentiating those patients from asymptomatic patients.     

Fetal cardiac and peripheral arterial flow velocity waveforms in intrauterine growth retardation

Maximum flow velocity waveforms were studied at the cardiac level (ascending aorta, pulmonary artery, and ductus arteriosus) and at the peripheral level (fetal internal carotid artery, descending aorta, umbilical artery, and maternal uteroplacental artery) in 25 patients with intrauterine growth retardation and 25 normal control subjects matched for gestational age and maternal parity. Gestational age ranged from 27 to 35 weeks (median, 30 weeks). All flow velocity waveforms were obtained with a mechanical sector scanner combined with a pulsed and continuous Doppler system with a carrier frequency of 3.5 and 3.0 MHz. Normal pregnancy was characterized by low fetal and placental vascular resistances. The peak systolic velocity in the ascending aorta was significantly higher compared with the pulmonary artery. In patients with intrauterine growth retardation, reduced end-diastolic flow velocities were documented in fetal descending aorta, umbilical artery, and maternal uteroplacental artery, reflecting raised umbilical placental and uteroplacental vascular resistances. Raised end-diastolic flow velocities were observed at the cerebral level, reflecting reduced cerebral vascular resistance ("brain sparing" effect). Reduced peak systolic flow velocities documented at the cardiac level may be secondary to reduced volume flow, increased valve or vessel size, or raised afterload. The noninvasive nature of this study did not allow differentiation between these variables.     

Idiopathic occlusion of the fetal ductus arteriosus without lumen narrowing

Constriction of the fetal ductus arteriosus in utero can be caused by pharmacological agents or can occur spontaneously. The spontaneous constriction and closure of the ductus arteriosus have been reported sporadically in the previous literature, either completely obliterated or constricted ductus arteriosus causing narrowing. This cardiac defect was characterized by no blood flow through the ductus arteriosus without lumen narrowing. The fetal echocardiography revealed the features of premature closure of the ductus arteriosus. We report a case of occlusion of the ductus arteriosus at 38 weeks of gestation that had a favorable postnatal outcome after immediate cesarean section.     

Validation of Doppler-derived pulmonary arterial pressure in patients with ductus arteriosus under different hemodynamic states

Twenty-nine patients with a patent ductus arteriosus (PDA) in isolation (n = 17) or in combination with other lesions (n = 12) underwent simultaneous hemodynamic assessment and evaluation of PDA flow velocity by the Doppler method. The accuracy with which Doppler velocity across the PDA predicted pulmonary arterial pressure and the influence of PDA size and shape on the Doppler velocity-pressure relationship were examined. Seventy percent had a cone-shaped PDA (narrowest at the pulmonary artery end), and the remainder were tubular. Narrowest PDA diameter ranged from 1.5 to 9 mm (mean 3.5 mm). Peak systolic and mean pulmonary arterial pressure ranged from 10 to 116 and 8 to 72 mm Hg, respectively. Twenty-one patients (group 1) had left-to-right shunting only. The following variables showed significant correlation in this group: peak instantaneous systolic aortic-to-main pulmonary arterial (MPA) pressure gradient and maximum Doppler velocity across the PDA (slope = 1.03, SEE = 13 mm Hg, r = .94, p less than .001), mean aortic-to-MPA pressure gradient and mean Doppler velocity (slope = 1.06, SEE = 10 mm Hg, r = .95, p less than .001), and end diastolic aortic-to-MPA pressure gradient and minimum Doppler velocity (slope = 1.12, SEE = 8 mm Hg, r = .96, p less than .001). Eight patients (group 2) had bidirectional shunting. In this group peak instantaneous aortic-to-MPA pressure gradient significantly correlated with maximum Doppler velocity measured from the left-to-right shunt (slope = .70, SEE = 2 mm Hg, r = .92, p less than .002) and mean pressure gradient correlated with mean Doppler velocity (slope = .83, SEE = 3 mm Hg, r = .78, p less than .003). Right-to-left Doppler velocities showed no correlation with pressures. In six patients with pulmonary hypertension Doppler velocity changes accurately predicted the effect of pulmonary vasodilation on pulmonary arterial pressure. Doppler velocity of PDA flow reliably predicts pulmonary arterial pressure over a wide range of pressures and PDA shapes and sizes.     

Transesophageal echocardiographic assessment of pulmonary veins and left atrium in patients undergoing atrial fibrillation ablation

Background: Pulmonary vein (PV) antrum isolation with ganglionated plexi (GP) ablation is a novel atrial fibrillation (AF) ablation technique. The aim of this study was to evaluate acute changes in left atrial and PV flow velocities following PV antrum isolation with GP ablation using transesophageal echocardiography (TEE). Methods: TEE was performed before and after PV antrum isolation with GP ablation in 88 consecutive patients. All four PVs, when possible, were analyzed with regard to peak systolic and diastolic pulsed‐wave Doppler flow velocities. Left atrial appendage emptying velocities were also obtained. PV stenosis was defined as a peak PV Doppler flow velocity of ≥110 cm/sec with spectral broadening (turbulence). Results: All but four right inferior and four left inferior PVs were visualized. Compared to preablation values, both PV systolic and diastolic velocities increased after ablation (P < 0.05 for each of the four PVs). However, the systolic to diastolic ratio decreased significantly after ablation in all PVs (1.3 ± 0.6 to 0.9 ± 0.4, P < 0.0001, 1.2 ± 0.7 to 0.9 ± 0.4, P < 0.0001, 1.2 ± 0.6 to 1.0 ± 0.6, P = 0.035 and 1.1 ± 0.5 to 0.9 ± 0.5, P = 0.0001, for left superior, left inferior, right superior and right inferior PV, respectively). Left atrial appendage emptying velocities showed a trend towards higher values following ablation (62.7 ± 26.1 cm/sec vs. 67.5 ± 23.2 cm/sec, P = 0.07). Asymptomatic PV stenosis occurred in seven patients (seven PVs). Conclusions: PV antrum isolation with GP ablation acutely increased PV flow velocities and altered the pattern of PV Doppler flow signal, likely correlating with increased left atrial pressures, but did not appear to adversely impact on left atrial appendage physiology. (Echocardiography 2011;28:775‐781)     

A comparison of regional myocardial velocity information derived by pulsed and color Doppler techniques: an in vitro and in vivo study

The objective was to compare velocity information derived from either a tissue mimicking phantom or normal contracting myocardium by both pulsed wave and color Doppler myocardial imaging (PWDMI and CDMI). Both CDMI and PWDMI allow quantitative assessment of regional myocardial contraction and relaxation velocities, but their potential clinical applications have not yet been investigated. Moreover, no information is available as to whether they can be used interchangeably for regional velocity assessment. For the in vitro study, a rotating, circular-shaped, tissue-mimicking sponge driven by a motor at speeds of 15, 30, 60, 90 rpm was used to derive velocity data from the same eight points of interest by using PWDMI or CDMI techniques. For the in vivo study, 25 normal subjects were examined at rest using parasternal and apical approaches. Velocity profiles were derived from the same 26 areas of interest (18 left ventricular segments, 3 right ventricular segments, and 5 measurement points for the tricuspid and mitral annuli) for each technique. Peak maximal velocities were detected by PWDMI and peak mean velocities were measured using CDMI. The results of the in vitro study phantom showed excellent correlation (r = 0.99, P < 0. 001) and satisfactory agreement (0.04 cm/sec; 3.3 cm/sec) between both Doppler techniques. PWDMI velocities were higher than CDMI velocities by up to 20% and overestimated the real velocity value (0. 37 +/- 0.29 cm/sec) while CDMI underestimated predicted velocity by 1.35 +/- 0.36 cm/sec. Good correlation (r = 0.87, P < 0.001), but poor agreement (-2.1 cm/sec; 5.4 cm/sec) was shown in vivo for all segments with regard to peak systolic and diastolic velocities. Both Doppler techniques cannot be used interchangeably for comparing peak velocities in the clinical situation. However, with adequate temporal resolution, they can be used interchangeably for velocity profile recording and for timing of events.