Two dimensional Doppler echocardiographic/M mode echocardiographic and phonocardiographic method for study of extracardiac heterograft valved conduits in the right ventricular outflow tract position

Significant concern exists over the long-term results of right ventricular outflow tract repair using heterograft valved conduits. Because these conduits and valves are difficult to image using ultrasound, a serially applicable two dimensional Doppler echocardiographic, M mode echocardiographic and phonocardiographic method for noninvasive investigation was developed and applied in 15 children. The method provides two dimensional echocardiographic imaging of valve contour and motion, as well as M mode and phonocardiographic analysis and quantitative range-gated Doppler information about the timing of flow through the conduit. Conduit diameter in two dimensional echocardiographic images correlated well with known conduit size (r = +0.96). A thickened and stenosed heterograft valve was predicted in two patients before hemodynamic investigation. This new method provides serially obtainable information to aid in the management of children and infants with a valved conduit placed for repair of congenital heart malformations and aids in planning the timing of hemodynamic follow-up studies.     

Serial echocardiographic profiles in infants and children with goarctation of the aorta

Eighty-three serial M mode echocardiograms were obtained from 13 medically managed infants and children aged 1 day to 3 1/2 years with coarctation documented at cardiac catheterization. Associated lesions included ventricular septal defect (two patients), atrial septal defect (two patients) and mild aortic stenosis (six patients). The echocardiograms were separated into four groups according to the patient's age: Group A, nine infants aged 1 day to 6 weeks; group B, nine infants aged 6 weeks to 4 months; group C, seven infants aged 4 months to 1 year; and group D, four children aged 1 to 3 1/2 years. Left ventricular diastolic dimension was significantly decreased in group A but gradually increased to normal with age. Right ventricular cavity dimension was significantly greater than normal in groups A and B and decreased toward normal with age. Right ventricular wall thickness was significantly increased initially and remained so. Septal and left ventricular posterior wall thickness measurements were not significantly different from normal in group A but increased progressively with age. Mean velocity of circumferential fiber shortening, corrected for heart rate, was significantly depressed in the youngest infants, despite digoxin therapy, but was normal thereafter. This study documents slight regression of right ventricular enlargement, left ventricular growth and hypertrophy and improvement in left ventricular function in growing infants and children with coarctation of the aorta. Echocardiography is useful in assessment of ventricular development in neonates with coarctation and in serial follow-up studies of cardiac adaptation to this lesion.     

Two dimensional echocardiography and intravenous digital video subtraction angiography for diagnosis and evaluation of double aortic arch

Two infants and one 7 year old child with double aortic arch are described in whom subcostal two dimensional echocardiography identified the bifurcation of the aorta high within the thorax and imaged the proximal portions of the right and left aortic arches. In one of the infants and in the 7 year old child, the diagnosis was confirmed using intravenous digital video subtraction angiography, thus avoiding aortography and permitting accurate evaluation of the anatomic features. All cases were confirmed surgically. If X-ray examination after barium swallow and clinical history are suggestive of double aortic arch, two dimensional echocardiography is useful in verifying this possibility. Intravenous digital video subtraction angiography provides the capability for precise documentation of the anatomic features.     

A new technique for noninvasive evaluation of femoral arterial and venous anatomy before and after percutaneous cardiac catheterization in children and infants

A new ultrasonic method was applied to image the femoral artery and vein in children for evaluation of short- and long-term effects of cardiac Catheterization with femoral percutaneous cannulation. Sixty-six children and infants (aged 5 days to 20 years) were studied with a 9 megahertz electronically focused real time scanner. Adequate studies were obtained in 46 patients before Catheterization, in 26 of 30 short-term follow-up studies and in 14 long-term follow-up studies. Femoral arterial size could be quantitatively measured at the inguinal ligament and a correlation existed between imaged femoral arterial diameter and body weight (r = + 0.82) or body surface area (r = + 0.80).Short-term follow-up ultrasonic imaging studies allowed diagnosis of spasm and other complications of percutaneous femoral arterial puncture. Long-term follow-up studies were performed 4 months to 3 years after Catheterization in 14 patients who had no complications recorded at the time of Catheterization. These revealed significant differences between vessels on the catheterized and uncatheterized (control) sides in only 3 of the 14. High resolution ultrasonic imaging can provide anatomic and functional information about femoral arteries and veins and appears to be of assistance in planning cardiac Catheterization and in studying the short- and long-term effects of percutaneous femoral cannulation.     

Results of surgery for congenital supravalvular aortic stenosis.

Of eight children aged 3 to 15 years with surgical correction of severe supravalvular aortic stenosis, 6 were evaluated 7 to 44 months later by repeat cardiac catheterization and aortography. Prosthetic patch angioplasty was performed in all cases. Preoperative systolic gradients ranged from 40 to 90 mm Hg (average 70); postoperative gradients ranged from 0 to 20 mm Hg (average 11). The postoperative anglographic appearance of the ascending aorta was near normal in all six patients, and none had new aortic valve insufficiency. These results of surgery for supravalvular aortic stenosis are judged to be excellent.     

Two-dimensional echocardiographic evaluation of dilated cardiomyopathy in children

This study examines and quantitates left ventricular (LV) short-axis 2-dimensional (2-D) echocardiograms of 16 normal control subjects and 19 patients who presented with clinical features suggestive of myocarditis leading to severe myocardiopathy. Of the 19 patients, 8 died or had cardiac transplantation: 9 were studied in the chronic phase and 10 in the acute phase. The endocardial surface of the LV short-axis image was digitized at chordal level at end-diastole and end-systole. Digitized traces in systole and diastole were superimposed. The cavity area of systole and diastole was determined and expressed as the percent systolic area reduction ratio. In the control subjects, the left ventricles were round in systole and diastole, contracted concentrically, and had a mean percent systolic area reduction of 53% (range 43 to 67). The left ventricle was not round in systole in the patients with myocarditis, and in 15, only the ventricular septum contracted significantly. Three patients had nonconcentric contraction, and regional contraction was more difficult to judge. The systolic area reduction ratio for the patients was 11 % (range 1 to 33), with no overlap with control subjects (p <0.001). Our results suggest that myocarditis more severely affects the LV free wall than the septum. In chronic patients, LV contraction remained markedly impaired. Quantitative evaluation of short-axis 2-D echocardiograms is a useful and sensitive technique for assessing damage due to presumed myocarditis.     

Role of M mode echocardiography in congenital aortic stenosis

M mode ultrasonic recognition of a bicuspid aortic valve or congenttally stenotic aortic valve rests on detection of the following criteria: eccentricity index, increased leaflet thickness, multiple diastolic cusp lines and presence of a central systolic line. In this investigation, M mode ultrasonic tracings from 118 children were interpreted by evaluators who did not know the diagnosis. Twenty-eight records from children with aortic valve stenosis (25 with a bicuspid valve and 3 with a tricuspid valve), were intermixed with records of 90 children with a catheterization-proved normal aortic valve to determine how many criteria were present in each tracing. Additionally, tracings were reviewed for overall visual appearance of the criteria, without measurement, to attempt to identtty those with an abnormal aortic valve. Finally, all echoes were viewed simultaneously and ranked from the most normal in appearance to the most abnormal aortic valve image. Rankings were then compared with measured pressure gradients across the aortic valve.

An eccentricity index value greater than 1.5, thought to be indicative of a bicuspid aortic valve, was found in 29 percent of patients with aortic stenosis and 20 percent of normal children. Mean eccentricity index values for the two groups were statistically similar. Increased leaflet thickness was not detected in any tracing. Multiple diastolic cusp lines were present in 64 percent of patients with aortic stenosis and 60 percent of normal children. None of these criteria were sensitive or selective for dlagnosing aortic stenosis from an M mode tracing of a given patiënt. On the basis of subjective visual appearance, 39 percent of tracings of patients with aortic stenosis were identified correctly. No useful correlation existed between the ranking an M mode tracing received for degree of valve normality or abnormality and the aortic pressure gradient. This investigation shows that M mode echocardiography of the aortic valve, despite prior recommendations to the contrary, has limited usefulness in diagnosing congenital aortic stenosis.     

Cross-sectional echocardiographic localization of sites of left ventricular outflow tract obstruction

Real time two-dimensional echocardiographic studies of left ventricular outflow tract cross-sectional anatomy were obtained by the multicrystal echocardiographic method (Bom system) in 35 patients with various types of outflow obstruction as delineated by clinical, hemodynamic and angiographic studies. In each patient the noninvasive test allowed prediction of the site of obstruction. In valvular aortic stenosis, echocardiographic diagnostic findings included poststenotic dilatation of the ascending aorta, thickened aortic cusp tissue and increased superior-inferior cusp excursion (doming). The site of supravalvular aortic stenosis was readily observed although echocardiographic findings often underestimated the degree of obstruction recorded at cardiac catheterization. In patients with discrete subvalvular aortic stenosis, the major finding was a localized thickening of the septum and anterior mitral anulus producing a narrowing of the left ventricular outflow tract that was present in diastole and persisted throughout the cardiac cycle. The combination of discrete subvalvular and valvular aortic stenosis could be identified as well as mitral valve abnormalities associated with left ventricular outflow tract obstruction. Asymmetric septal hypertrophy and systolic anterior motion of the mitral leaflets were noted in six patients with idiopathic hypertrophic subaortic stenosis. This new echocardiographic approach allowed accurate localization of the site of left ventricular outflow tract obstruction and detection of associated malformations. The method has substantial merit as an initial test to establish diagnosis and allows more appropriate planning of a subsequent hemodynamic study.     

Doppler echocardiographic prediction of pulmonary arterial hypertension in congenital heart disease

This study determines the accuracy of Doppler echocardiography (echo) for predicting the presence of pulmonary artery (PA) hypertension from Doppler PA velocity traces. The patient group included 17 patients with congenital cardiac disease who had undergone catheterization. The control group was composed of 15 normal subjects. Doppler traces were analyzed qualitatively and quantitatively. Qualitative assessment included evaluation for a negative presystolic velocity that was the equivalent of the pulmonary a wave detected by M-mode echo. Quantitative assessment included measurement of the following time intervals and ratio of intervals: preejection period (PEP), time to peak velocity (TPV), right ventricular ejection time (RVET), PEP/RVET and TPV/RVET ratios. In the patient group, systolic PA pressure ranged from 22 to 90 mm Hg (mean 50 +/- 23), and mean PA pressure ranged from 12 to 60 mm Hg (mean 32 +/- 17). Five patients had systolic PA pressures of less than or equal to 30 mm Hg and 12 had systolic PA pressures greater than 30 mm Hg. Of 15 control subjects, 14 had a negative presystolic a wave. Of 5 patients with PA pressure less than or equal to 30 mm Hg, 4 had a presystolic negative velocity, and all with higher pressures had no presystolic negative velocity. One patient with pressure less than 30 mm Hg and 2 with PA pressure greater than 30 mm Hg had indeterminate status of presystolic velocity pattern because of turbulence or baseline blanking. The best quantitative indexes for separating patients with normal PA pressure from those with elevated PA pressure were TPV and TPV/RVET, which respectively correlated negatively with systolic PA pressure (r = -0.82, standard error of the estimate [SEE] = 0.02; and r = -0.70, SEE = 0.05). These measurements also correlated negatively with mean PA pressure (r = -0.75, SEE = 0.02; and r = -0.76, SEE = 0.05). Other intervals and ratios had enough individual variability to make them less useful as predictors of PA hypertension.     

In vitro verification of Doppler prediction of transvalve pressure gradient and orifice area in stenosis

This study was designed to analyze the validity of application of the modified Bernoulli equation (pressure gradient = 4.0 X velocity2) for estimating the pressure drop and valve orifice area from the jet velocity measured by Doppler ultrasound. We used an in vitro model which permitted interchangeable orifices, accurate measurement of the valve area and pressure drop across the valve. An in-line Doppler ultrasound transducer measured jet velocity (VEL D) at various water flow rates at an incident angle of 180 degrees beyond the various tested orifices. Jet velocity was also determined independently by application of a modified Bernoulli equation using the experimentally measured pressure drop (VEL P) and by a standard continuity equation (VEL Q). VEL P correlated very closely with VEL D (r = 0.981, standard error of the estimate [SEE] = 17.0 and slope of the regression = 0.988). VEL Q, corrected for vena contracta effects, correlated with VEL P (r = 0.986, SEE = 21.6), but had a slope of 0.673. To experimentally determine the exponent of velocity in the Bernoulli equation, we plotted pressure drop against VEL D and found a value of 2.11; theory predicts 2.0. Experimental coefficient of velocity was 3.36 torr/m (standard deviation = 0.52), whereas theory predicts 3.75 for water. Orifice area, calculated using VEL D and the continuity equation, was consistently overestimated by 3 to 12% for flows that produced laminar jets. The pressure gradient and orifice areas calculated from Doppler-derived data accurately predict actual pressure gradients and orifice areas.     

Evaluation of pulmonary and systemic blood flow by 2-dimensional Doppler echocardiography using fast fourier transform spectral analysis

This study was designed to assess the accuracy and problems of noninvasively measuring right and left cardiac output by range-gated pulsed Doppler echocardiography. Sixteen children with cardiac disease, aged 3 months to 17 years, served as the subjects; 2-dimensional range-gated pulsed Doppler echocardiographic data were unobtainable in 2 children, leaving 14 for study. Diagnoses included shunt lesions, valvular abnormalities, coarctation, repaired defects, and Kawasaki's disease. The equipment for this study included a 2-dimensional echocardiographic Doppler sample volume locator. The Doppler frequency shift was analyzed by fast Fourier transform. Twenty 2-dimensional range-gated pulsed Doppler echocardiographic measurements (10 pulmonary and 10 aortic) were made simultaneously with indicator dilution outputs or angiographic outputs. In 4 subjects, 2-dimensional range-gated pulsed Doppler echocardiographic aortic outputs were not possible. For this study, vessel diameter was determined by both echocardiography and angiography, Doppler intercept angle by 2-dimensional echocardiography, and velocity by 2-dimensional range-gated pulsed Doppler echocardiography. Comparison of cardiac output measurements obtained by invasive methods and by 2-dimensional range-gated pulsed Doppler echocardiography (angiographic vessel measurement) showed a correlation of +0.94 (standard error of the estimate [SEE] = 0.53) with a slope of y = 0.83 × + 0.61, indicating that the slope and line of identity were almost equal and the offset from 0 was small. For 2-dimensional range-gated pulsed Doppler echocardiography (echocardiographic vessel measurement), the correlation was +0.94 for aortic flow but only +0.72 for pulmonary flow. Problems encountered in some patients included turbulence, which made velocity measurements unreliable, difficulty in obtaining aortic flow by Doppler echocardiography due to transducer configuration, and measurement of pulmonary diameter by echocardiography. The results indicate that 2-dimensional range-gated pulsed Doppler echocardiographic outputs are accurate under conditions of nonturbulent or minimally turbulent flow and adequate imaging, but only when vessel diameter can be accurately measured.     

Two-dimensional echocardiographic study of right ventricular outflow and great artery anatomy in pulmonary atresia with ventricular septal defects and in truncus arteriosus

In this study, we reviewed M-mode and two-dimensional (2DE) echocardiographic observations in 13 patients with pulmonary atresia with ventricular septal defect and in six patients with truncus arteriosus in order to attempt to identify echocardiographic features distinguishing these two abnormalities in which no anatomic connection exists between the right ventricle and the pulmonary artery. M-mode features compatible with the diagnosis of pulmonary atresia with a ventricular septal defect (VSD) were a small but identifiable space anterior to the aorta and/or immobile pulmonic valve echoes appearing to open during diastole rather than systole. By 2DE, the proximal and distal segments of the right ventricular outflow tract could be imaged and the length of the atretic segment estimated. In truncus arteriosus, no outflow tract of the right ventricle could be identified by 2DE or M-mode echocardiography, and the origin of the pulmonary artery from the truncus could be imaged directly in four patients with type I and in one patient with type II truncus. Abnormalities of the truncal valve were also present and were imaged by 2DE in three of our five patients. Our study identified specific echocardiographic criteria for diagnosing truncus arteriosus and pulmonary atresia with VSD and for differentiation between them.     

Prenatal ultrasound diagnosis of hypoplastic left heart syndrome in utero associated with hydrops fetalis

Ultrasound is widely used in obstetrics as a screening technique for fetal size and maturity, placental structure and function, and for detection of fetal congenital malformations in complicated pregnancies.^1–3 Our own work on qualitative and quantitative fetal echocardiography^4,5 and the work of others⁶ has suggested that high resolution ultrasound can be used to assess fetal heart rhythm and function, and can detect congenital heart malformations before birth. In this report, we delineate prenatal diagnosis of hypoplastic left heart syndrome in a fetus with signs of hydrops fetalis, who was found after cesarean section to have associated trisomy 13. Additionally, we diagnosed the ususual occurrence of an intraventricular thrombus within the hypoplastic left ventricular cavity. The fetal ultrasound evaluation was of major importance in the perinatal management of both mother and unborn child.     

Effect of beam directional alterations on left ventricular shortening fraction

In this study, the dependence on beam direction of the echocardiographically derived fractional shortening of the left ventricular minor axis was evaluated. A directionally oriented, steerable cursor was used to select M-mode lines from a 2-dimensional image at the chordal level. Seven M-mode traces were derived from each image, 1 along the true ventricular meridian and 3 at known deviations on either side of the meridian. M-mode traces, thus derived, all appeared acceptable for measuring wall or cavity dimensions. Results indicate a progressive increase in shortening fraction (p less than 0.05) for deviations more than 25% of the distance between the meridian and the lateral or medial papillary muscle heads. Decreases in left ventricular dimensions in diastole and systole with progressive deviation from the meridian accounted for the decrease in shortening fraction. Spatial orientation is required for reproducible shortening fraction measurements.     

New serial contrast technique for assessment of left to right shunting patent ductus arteriosus in the neonate

A new serial echocardiographic contrast technique for detection of patent ductus arteriosus has been developed and validated by clinical course (33 infants), surgical observations (13 infants) and autopsy observations (4 infants). A left to right shunting patent ductus arteriosus was demonstrated in 30 of 33 prospectively studied premature infants (mean weight 1,371 g) using this new contrast method. The demonstration of left to right ductal shunting was accomplished by hand injection of a nonviscous material (saline solution, 5 percent dextrose in water or the patient's own blood) through an umbilical arterial catheter placed with its tip located above the diaphragm during recording of a suprasternal notch echocardiogram. In positive studies, both the transverse aortic arch and right pulmonary artery were opacified. If no left to right shunt existed, only the transverse aortic arch was opacified.This serial study helped elucidate the natural history of patent ductus arteriosus. Twenty-four of the 30 patients with a positive study initially had a left to right shunting patent ductus arteriosus without an audible murmur. Three of these patients with silent patent ductus arteriosus later had congestive heart failure and two required operative ligation of the patent ductus. The high rate of detection of silent patent ductus arteriosus and its bedside confirmation when suspected are important in the serial management of critically ill newborns with this condition. The test is safe and sensitive and it is useful for early demonstration of silent patent ductus arteriosus, for clarifying the origin of murmurs and for confirming spontaneous, operative or pharmacologie closure of a patent ductus arteriosus.     

Prognostic value of left ventricular size measured by echocardiography in infants with total anomalous pulmonary venous drainage

Left ventricular size may be a determinant of survival in infants with total anomalous pulmonary venous drainage. Right and left ventricular size were measured by M-mode and 2-dimensional (2-D) echocardiography in 13 patients aged 1 day to 4 months (mean weight 4.3 ± 0.42 kg [standard error of the estimate]) who underwent surgery before age 4 months because of severe cyanosis or cardiac failure. Seven patients had venous drainage to a vertical vein, 4 had drainage to the right atrium, and 2 had drainage to the inferior vena cava. Patients were divided into 2 groups: survivors (Group A, n = 8) and nonsurvivors (Group B, n = 5). Death was not statistically related to pulmonary artery pressure, pulmonary venous obstruction, age, or weight at the time of surgery. Right and left ventricular sizes at end-diastole measured from M-mode traces and 2-D echocardiographic 4-chamber views were compared with those from 15 weight-matched control infants. On M-mode and 2-D echocardiography, nonsurvivors had significantly larger right ventricles and smaller left ventricular dimensions than did either control subjects or surviving patients with total anomalous pulmonary venous drainage. The ratio of right to left ventricular size on M-mode and 2-D echocardiography also differed among the 3 infant groups (p < 0.001). The ratio of right to left ventricular size differentiated nonsurvivors from survivors and control subjects. Postmortem examinations available in 4 of the 5 nonsurvivors demonstrated that the ratio of right to left ventricular size in the specimens closely agreed with the 2-D echocardiographic ratios. Our study agrees with the impression of other investigators that left ventricular size may be a determinant of survival after repair of total anomalous pulmonary venous drainage.     

Factors affecting accuracy of in vitro valvar pressure gradient estimates by Doppler ultrasound

Doppler ultrasound is used successfully in clinical situations for noninvasive measurement of pressure changes across stenotic cardiac valves. However, situations that might lead to errors in measurement have not been identified. This study determines the effect of flow rate, viscosity, orifice shape and size on the calculation of Doppler transvalvar gradient. Pressure gradient is usually computed from the equation P1-P2 = 4 X Vmax2, where P1-P2 is the gradient and Vmax is the maximal jet velocity measured by Doppler ultrasound. An in vitro model was developed with interchangeable orifices that permitted the jet to be detected by an in-line Doppler transducer. The model allowed alteration of flow rates, viscosities and pressure gradients. When P1-P2 as predicted by Doppler was compared with that measured by manometers (PM), excellent correlations were obtained for triangular orifices of areas as small as 78.5 mm2 (r = 0.95) and for circular and elliptical orifices to as small as 50.2 mm2 (r = 0.99). For smaller orifices, P1-P2 correlated poorly with PM. Good correlation was found between P1-P2 and PM, with flow rates ranging from 0.7 to 8.4 liters/min (r = 0.97) with a 10-mm diameter circular orifice (area = 78.5 mm2). No observable differences were found in the accuracy of the equation between high and low flow rates. Viscosity had no effect on the accuracy of the P1-P2 comparison with PM over the range evaluated (1 to 10 cp). It is concluded that the modified Bernoulli Doppler gradient equation provides accurate results in the usual clinical situation when an orifice permits true jet formation.