Anirban Banerjee

Postoperative evaluation of pulmonary arteries in congenital heart surgery by magnetic resonance imaging: Comparison with echocardiography

Palliative and corrective operations for the treatment of cyanotic congenital heart disease frequently involve or potentially influence the size of the pulmonary arteries. Echocardiography and magnetic resonance imaging (MRI) are two noninvasive imaging techniques currently used to assess morphologic abnormalities of the pulmonary arteries. The purpose of this study was to evaluate the role of MRI in comparison with echocardiography for defining morphologic changes of the pulmonary arteries after congenital heart surgery. The MRI scans and echocardiograms of 33 patients with surgery involving or affecting the pulmonary arteries were compared. The pulmonary outflow tract, pulmonary confluence, right and left pulmonary arteries, and surgical shunts were separately evaluated. Cineangiography and surgical reports were used to confirm findings. MRI and echocardiography were equivalent for demonstrating abnormalities of the right ventricular outflow tract, main pulmonary artery, and a variety of pulmonary shunts. MRI was superior to echocardiography in demonstrating abnormalities of the right and left pulmonary arterial branches (p < 0.001). MRI is effective for monitoring pulmonary arterial status after surgery and is superior to echocardiography for the evaluation of the right and left pulmonary arteries.

Hepatic Venous Malformation After Modified Fontan Procedure With Partial Hepatic Vein Exclusion

Partial hepatic vein exclusion, as an alternative to baffle fenestration, has been performed as a modification of the Fontan procedure. We report a case of severe cyanosis resulting from massive right-to-left shunting via a hepatic vascular malformation that developed in a patient after a modified Fontan procedure with partial hepatic vein exclusion.

Pulmonary venous flow doppler velocities in children

We report the results of a prospective study of pulmonary venous (PV) flow Doppler velocities in 68 normal children. We sought to establish the normal PV flow velocities in the broad pediatric population, compare these velocities to heart rate and age. In normal children, there is a wide range of PV flow velocities, most of which correlate with age and heart rate. However, the PV flow velocities and their durations do not distinguish the age groups. The peak velocity of systolic forward flow and atrial reversal flow in the pulmonary vein were independent of heart rate. The PV flow peak systolic velocity showed a weak correlation with the velocity of the mitral inflow early wave. However, the velocity of atrial reversal flow showed no correlation with the mitral inflow A velocity (late wave), which is generated by the same force of atrial contraction.

Predictors of successful pulmonary balloon valvuloplasty: 10‐year experience

At our institution, 55 infants and children (ages 0.3-21 yr, median 2.5 yr) underwent pulmonary balloon valvuloplasty between August 1983 and May 1993. Systolic pressure gradients fell acutely following balloon valvuloplasty from 63.5 +/- 24.8 mmHg (mean +/- standard deviation) to 26.7 +/- 12.9 mmHg (P < 0.001) with a decrease in systolic pressure ratio from 0.81 +/- 0.25 to 0.42 +/- 0.12 (P < 0.0001). Fifty of the 55 patients had long-term echocardiographic evaluation performed > 2 yr following balloon valvuloplasty. Thirty-four of the 50 patients (Group A; 68%) were classified as having successful (residual systolic gradients < 25 mmHg, ventricular systolic pressure ratios < 0.6) long-term outcomes. Their peak systolic gradients fell acutely from 58.8 +/- 16.6 mmHg to 22.7 +/- 11.2 mmHg (P < 0.001). At 4.6 +/- 2.3 yr postvalvuloplasty, peak instantaneous pressure gradients were 17.8 +/- 5.7 mmHg (P = ns vs. acute postvalvuloplasty). Fifteen of the 50 patients (Group B; 30%) had unsuccessful (residual systolic gradients > or = 25 mmHg and/or ventricular systolic pressure ratios > 0.6) long-term outcomes. Their peak instantaneous systolic gradients fell acutely from 76.5 +/- 33.1 mmHg to 36.6 +/- 11.4 mmHg (P < 0.05). At 3.8 +/- 1.7 yr postvalvuloplasty, peak instantaneous pressure gradients were 35.1 +/- 9.1 mmHg (P = ns vs. acute postvalvuloplasty). One 3-yr-old patient (Group C, 2%) required repeat balloon valvuloplasty on two separate occasions for recurrent stenosis. There was no significant prevalvuloplasty difference between Groups A and B with regard to age, weight, or Z scores of the pulmonary annuli or balloon/annulus ratio; however, patients in Group A had significantly lower prevalvuloplasty gradients and lower systolic pressure ratios than patients in Group B. Total systolic gradient reduction between patients with successful and unsuccessful outcomes was not significantly different (Group A: 36.1 +/- 16.6 mmHg; Group B: 41 +/- 22.3 mmHg). At long-term follow-up, patients in Group A had fewer symptoms and a significantly lower rate of electrocardiographic right ventricular hypertrophy than Group B patients. Successful outcomes defined by our criteria following balloon valvuloplasty were achieved in 68% of patients with greatest long-term success in patients with prevalvuloplasty systolic gradients < 60 mmHg and systolic pressure ratios < 0.8. Intervention at lesser systolic gradients (40-60 mmHg) appears indicated to achieve lower long-term gradients and fewer symptoms as total systolic gradient reduction by this technique is limited.

Nonlinearity of the left ventricular end-systolic wall stress-velocity of fiber shortening relation in young pigs: A potential pitfall in its use as a single-beat index of contractility

OBJECTIVESnWe sought to evaluate in the young heart the primary assumptions on which the current use of the mean velocity of fiber shortening corrected for heart rate as a noninvasive index of contractility are based.nnnBACKGROUNDnEnd-systolic wall stress-velocity of fiber shortening relation has been applied as a single-beat, load-independent index of contractility in children. This use is based on poorly validated assumptions of linearity, parallel shifts with changing contractile state and inotropic sensitivity of the end-systolic wall stress-velocity of fiber shortening relation.nnnMETHODSnIn eight anesthetized young piglets, 5F mciromanometric catheters were placed in the ascending aorta and balloon occlusion catheters in the descending aorta. End-systolic wall stress and velocity of fiber shortening were calculated from aortic pressure and M-mode echocardiography under six conditions: in three contractile states 1) baseline, 2) increased contractility during dobutamine infusion (10 micrograms/kg per min), and 3) decreased contractility after propranolol injection (1 mg/kg), each at two afterload states (normal and increased load by partial aortic occlusion).nnnRESULTSnDobutamine increased and propranolol decreased afterload-matched velocity of fiber shortening corrected for heart rate significantly to 140% and 77% of baseline, respectively. However, the slope of end-systolic wall stress-velocity of fiber shortening relation was much greater (251% of baseline) during dobutamine infusion, which also significantly decreased wall stress, and was much less (27% of baseline) after propranolol injection, which increased wall stress.nnnCONCLUSIONSnThe velocity of fiber shortening corrected for heart rate did change predictably with changes in contractility and as such can be used noninvasively in the temporal evaluation of individual patients undergoing therapeutic interventions or to define the natural history of a disease process. However, the relation on which it is based is not defined by parallel straight lines across contractile states, so that abnormal single point measurements may reflect only the nonlinearity of the relation rather than abnormalities in contractility. Thus, we recommend that the end-systolic wall stress-velocity of fiber shortening relation should not be used as a single-beat index of contractility.

Echocardiographic characteristics of successful deployment of the Das AngelWings atrial septal defect closure device: initial multicenter experience in the United States.

The AngelWings device is a newer transcatheter device used for closure of secundum atrial septal defects (ASD) and patent foramen ovale (PFO), which consists of a self-centering, 2-disk system. Transesophageal echocardiography (TEE) plays a pivotal role in the deployment of the 2 disks of this device, on the appropriate sides of the atrial septum. The objective of this study is to describe the echocardiographic findings associated with successful deployment of the AngelWings device for closure of ASD and PFO. We evaluated the TEE studies of 70 patients enrolled in 4 United States centers, for closure of ASD and PFO with the AngelWings device. The TEE characteristics of successful and unsuccessful deployments were analyzed. Residual shunts across the atrial septum were assessed by TEE at the end of the procedure, 24 hours later by transthoracic echocardiography, and at 6 months by TEE. The deployment of the device was successful in 65 patients (93%). In the unsuccessful group, ASD size by TEE was larger (13.4 +/- 3.1 vs 8.9 +/- 4.7 mm, p <0.05). TEE was successful in identifying snagging of the device by intracardiac structures and prolapse of corners of the left or right atrial disk through the ASD, features that were difficult to identify by fluoroscopy. The echocardiographic characteristics outlined here are important guidelines for successful deployment of the AngelWings device.

Is echocardiography or magnetic resonance imaging superior for precoarctation angioplasty evaluation

We compared the dimensions of the aorta obtained by two-dimensional transthoracic echocardiography (echo) (median, 2.5 mo preangioplasty) and magnetic resonance imaging (MRI) (median, 4.2 mo preangioplasty) to those obtained by angiography (cath) in 13 patients (age, 7.7 +/- 1.6 yr; mean +/- SEM) who underwent evaluation for coarctation balloon angioplasty between April 1993-January 1996. Echo measurements were obtained from the suprasternal and subcostal sagittal planes, MRI measurements from axial and sagittal oblique views, and cath measurements from the straight lateral or oblique views. Measurements of the diameters of the aortic isthmus, coarctation, descending aorta at the diaphragm, and isthmus length were made by all three modalities. Presence of aorto-aortic collaterals was determined, and the coarctation length was delineated. Investigators were blinded to other measurement data prior to statistical analysis. Data analysis by repeated analysis of variance (ANOVA) and Student-Newman-Keuls testing revealed no statistically significant difference between systolic pressure gradient by clinical examination (32.2 +/- 5.9 mm Hg), peak instantaneous Doppler evaluation (37.5 +/- 2.9 mm Hg), or preangioplasty systolic pressure gradient (32.1 +/- 3.3 mm Hg). With the exception of measurements of the descending aorta (echo, 11.7 +/- 0.9 mm vs. MRI, 13.3 +/- 0.8 mm vs. cath, 14.0 +/- 1.3 mm; P = 0.04), there was no statistically significant difference in dimensions of the aortic isthmus (9.2 +/- 0.6 mm vs. 10.5 +/- 0.9 mm vs. 10.8 +/- 0.9 mm), coarctation site diameter (4.8 +/- 0.6 mm vs. 5.6 +/- 0.9 mm vs. 5.3 +/- 0.8 mm), or isthmus length (12.4 +/- 2.1 mm vs. 12.1 +/- 2.2 mm vs. 10.9 +/- 1.7 mm). The correlation coefficients derived from comparisons of MRI vs. cath to echo vs. cath were similar for all dimensions except for isthmus length (P < 0.01). MRI demonstrated aorto-aortic collaterals more frequently than echo, while echocardiography better demonstrated cardiac function and intracardiac anomalies. Both modalities detected the single patient with a long segment coarctation. We conclude that echocardiography and MRI provide similar definition of the coarcted thoracic aorta, and either test may be individually advantageous in specific clinical situations.

Effect of myocardial hypertrophy on systolic and diastolic function in children : Insights from the force-frequency and relaxation-frequency relationships

OBJECTIVEnThe objective of this study was to evaluate the effect of myocardial hypertrophy on systolic and diastolic properties of the left ventricle in children.nnnBACKGROUNDnIn children with myocardial hypertrophy, ejection phase indices are invariably increased. However, indices of force-generation, e.g., end-systolic elastance and invasive indices of diastolic properties, have been studied infrequently in children with myocardial hypertrophy.nnnMETHODSnWe studied 10 children with congenital aortic stenosis or coarctation of aorta and nine control patients. Systolic properties were assessed from shortening fraction, end-systolic fiber elastance (Ef(es)) measured at resting heart rates, and force-frequency relationship measured at heart rates increasing from 110 to 160 beats per minute. Diastolic properties were assessed from time constant of relaxation (tau) at matched heart rates, chamber stiffness constant, myocardial stiffness constant, and relaxation-frequency relationship measured at gradually increasing heart rates.nnnRESULTSnEf(es) remained unchanged by myocardial hypertrophy, however, tau was prolonged (tauL: 27.3+/-2.3 vs. 21.8+/-2.2 ms, p < 0.001; and tauD: 43.2+/-3.1 vs. 34.3+/-3.3 ms, p < 0.001). Both chamber and myocardial stiffness constants remained unchanged. Incremental increases in heart rate produced incremental improvement in both contraction and relaxation. Slopes of force-frequency and relaxation-frequency relationships remained unchanged in the experimental group. However, the relaxation-frequency relationship manifested a parallel shift upward.nnnCONCLUSIONSnIn conscious, sedated children with myocardial hypertrophy, systolic function assessed by an index of force generation remains unchanged. However, relaxation is prolonged but passive diastolic properties remain unaffected. The combined effect of hypertrophy and heart rate does not alter the force-frequency and relaxation-frequency relationships.

Bradykinin receptor blockade does not affect oxygen-mediated pulmonary vasodilation in fetal lambs

ABSTRACT: Both oxygenation and rhythmic stretching of the lungs are factors known to be responsible for pulmonary vasodilation at birth. Based on our previous studies, we proposed that the pulmonary vasodilation caused by oxygen could be mediated, at least in part, through bradykinin release. To test this hypothesis, we evaluated the cardiovascular responses to in utero ventilation during infusion of a B2 subtype bradykinin receptor antagonist (BKA), [N-ada-mantaneacetyl-D-Argo,Hyp3,Thi5,8,D-Phe7]bradykinin, at 15–20 μg·kg−1·min−1 in eight near-term fetal lambs and during drug vehicle infusion in five control fetal lambs. Prostacyclin synthesis was inhibited by meclofenamate infusion (1.5 mg·kg−1·h−1). Surgical placement of vascular catheters, a flow transducer around the left pulmonary artery, and a tracheostomy tube and formalin infiltration of the ductus arteriosus to maintain its patency in the presence of meclofenamate were performed 72 h before the study. Hemodynamic variables and pulmonary blood flow were measured and pulmonary vascular resistance was calculated before and after in utero ventilation with 100% oxygen. Despite complete blockade by BKA of the pulmonary vasodilation produced by exogenous bradykinin, ventilation with oxygen significantly increased pulmonary blood flow by 676% over baseline state (157.8 ± 66 to 1224 ± 265 mL·min−1-−100 g−1 p < 0.01) and decreased the pulmonary vascular resistance by 89% from baseline state (0.44 ± 0.16 to 0.048 ± 0.01 torr-mL−1·min·100g,p < 0.01). Such responses to ventilation with oxygen were comparable to those noted in the control animals, in whom bradykinin receptors had not been blocked. We conclude that bradykinin receptor blockade does not inhibit or attenuate the pulmonary vasodilatory response caused by oxygen in fetal lambs, thereby suggesting that bradykinin release is not critical for oxygen-mediated pulmonary vasodilation.

Left Ventricular Rotational Mechanics before and after Exercise in Children

BACKGROUNDnIn children, there is limited information regarding the relative contribution of left ventricular (LV) apical and basal rotation to increase LV pump function with exercise. The aim of this study was to test the hypothesis that a progressive increase in LV pump function with exercise is related to increased LV apical and basal rotation.nnnMETHODSnForty-two subjects 12 to 18 years of age with normal cardiac structure and function were recruited prospectively and imaged at rest, and in 20 subjects, imaging was repeated after moderate exercise. Conventional measures of LV systolic and diastolic performance were evaluated. Left ventricular rotation, LV twist, rotational rate, and recoil and untwist rates were measured using two-dimensional speckle-tracking echocardiography. Torsion was calculated by normalizing LV twist to LV diastolic length. Twist displacement loops were constructed from data obtained at rest and after exercise.nnnRESULTSnApical rotation increased significantly after exercise (7.33 ± 2.8° vs 11.6 ± 4.7°, P = .0004), but basal rotation did not (-4.85 ± 1.9 vs -6.46 ± 4.81, P = .21). Similarly, peak twist, torsion, and twist rate also increased significantly after exercise. In diastole, apical recoil rate and LV untwist rate also increased significantly with exercise. The slope of the systolic limb of the twist displacement loop and the area enclosed by the loop also increased significantly with exercise.nnnCONCLUSIONSnIncreases in global LV pump function during exercise in children are associated with enhanced LV apical rotation but not LV basal rotation. In addition, unique changes were seen in twist displacement loops in children before and after exercise. These data may serve as a foundation for understanding future applications of LV rotational mechanics in disease states.