Pulmonary blood flow distribution in transposition of the great arteries

Pulmonary blood flow distribution was studied by scintillation scanning of the lungs after the infusion of iodine-131-labeled macroaggregates of human albumin before and after the Mustard operation in 53 patients with transposition of the great arteries. The patients were classified as follows: Group I (24 infants with uncomplicated transposition of the great arteries); Group II (18 patients with transposition and ventricular septal defect); and Group III (11 patients with transposition, ventricular septal defect and pulmonary obstruction).Before operation, 21 patients had a normal distribution of pulmonary blood flow, 10 had preferential flow to the right lung and 2 had preferential flow to the left lung. After operation, 19 had a normal pattern of pulmonary blood flow, 21 had preferential flow to the right lung and 3 had preferential flow to the left lung. The scanning studies have proved helpful in follow-up of patients to rule out recurrence of the shunt, pulmonary or systemic venous obstruction, development of pulmonary hypertension and occlusion of a palliative systemic-pulmonary shunt.     

Factors influencing systemic arterial oxygen saturation in complete transposition of the great arteries

Hemodynamic data from 100 patients with complete transposition of the great arteries, all 1 year old or older, were reviewed. Only 2 patients, at rest and breathing room air, had a systemic arterial oxygen saturation level as high as 85 percent. In any patient with dextrotransposition of the great arteries and a systemic arterial saturation of 85 percent or greater, there is a strong likelihood of a single ventricle.

At a given level of oxygen consumption, 3 potential variables influence systemic arterial oxygen saturation in transposition: (1) magnitude of the intercirculatory mixing, (2) hemoglobin concentration and (3) magnitude of the recirculated systemic mixed venous flow. The first 2 factors are directly related to systemic saturation, and the third is inversely related.

Decreasing total pulmonary blood flow, secondary to increasing pulmonary vascular disease or pulmonary stenosis, results in decreased intercirculatory mixing and a decrease in systemic arterial oxygen saturation. This decrease in saturation is partially compensated for by an increase in hemoglobin concentration. An index calculated from the level of systemic arterial oxygen saturation divided by the value for hemoglobin concentration is useful in follow-up studies to determine the presence of pulmonary vascular disease or pulmonary stenosis. This index will often eliminate the need for repeated cardiac catheterizations before definitive corrective surgery is carried out.     

Role of prostaglandin E1 infusion in the management of transposition of the great arteries.

That prostaglandin E₁ can produce an increase in systemic oxygen saturation in patients with cyanotic heart disease and ductus dependent pulmonary blood flow has been well documented. However, its use in complete transposition to increase systemic oxygen saturation by increasing mixing has not been well investigated. Ten newborn infants with angiographic diagnosis of d-transposition of the great arteries and patent ductus arteriosus were studied; 6 had an intact ventricular septum. Prostaglandin E₁ infusion (0.1 μg/kg per min) was started after balloon atrial septostomy because of a persistently low systemic oxygen saturation of 26 ± 12 percent (mean ± standard deviation) and oxygen tension of 17 ± 5 torr. The infusion resulted in an increase in systemic oxygen saturation to 53 ± 19 percent (P < 0.01) and oxygen tension to 30 ± 9 torr (P < 0.001). In 2 of 10 patients, there was no increase in systemic oxygen saturation with the infusion (1 had the infusion before the septostomy and both had the infusion for less than 10 minutes). In 8 of 10 patients, the infusion was continued from 4 to 312 hours (average 98 hours) until a Blalock-Hanlon procedure was performed. Two babies became septic, and one of them died. A third had a transient fever. All children whose prostaglandin E₁ infusion was discontinued before atrial septectomy had a reduction in systemic oxygen saturation to unacceptable levels. Two patients who required infusion (for 5 days) after septectomy were successfully weaned from the drug.It is concluded that dilation of the ductus by prostaglandin E₁ infusion increases pulmonary blood flow (left to right shunt) which in turn favorably influences atrial mixing (left to right shunt) and increases systemic oxygen saturation. Pulmonary blood flow may be further increased by a decrease in pulmonary vascular resistance induced by prostaglandin E₁.     

Indicator dilution curves in the diagnosis of D-transposition of the great arteries in infancy.

Paired right and left atrial indicator dilution curves performed in a series of 17 patients with D-transposition of the great arteries (D-TGA) were reviewed. Taken together, the patterns obtained from patients who had trivial mixing between the pulmonary and systemic circulations were distinctive and easily recognizable. In the presence of substantial degrees of intracardiac mixing, however, the paired curves recorded become virtually identical and cannot be distinguished from curves recorded from patients with other forms of cyanotic congenital heart disease characterized by obligatory admixture. Thus paired atrial dye curves demonstrate a high degree of diagnostic specificity for the infant with D-TGA at greatest risk, normally those with a small intracardiac shunt. Such a procedure should facilitate early balloon atrial septostomy and obviate deterioration in the infant's condition due to prolonged catheter manipulation and/or angiography.     

Indicator dilution curves in the diagnosis of D-transposition of the great arteries in infancy

Paired right and left atrial indicator dilution curves performed in a series of 17 patients with D-transposition of the great arteries (D-TGA) were reviewed. Taken together, the patterns obtained from patients who had trivial mixing between the pulmonary and systemic circulations were distinctive and easily recognizable. In the presence of substantial degrees of intracardiac mixing, however, the paired curves recorded become virtually identical and cannot be distinguished from curves recorded from patients with other forms of cyanotic congenital heart disease characterized by obligatory admixture. Thus paired atrial dye curves demonstrate a high degree of diagnostic specificity for the infant with D-TGA at greatest risk, normally those with a small intracardiac shunt. Such a procedure should facilitate early balloon atrial septostomy and obviate deterioration in the infant's condition due to prolonged catheter manipulation and/or angiography.     

Double outlet right ventricle: clinical spectrum and prognosis.

Patients with double outlet right ventricle can be separated into four distinct groups. In the largest (Group III), patients have a subaortic ventricular septal defect and pulmonary stenosis and clinically resemble patients with tetralogy of Fallot. In the next largest group (Group I), patients have a subpulmonry ventricular septal defect and no pulmonary stenosis and clinically resemble children with D-transposition of the great arteries and a ventricular septal defect. These patients have a high rate of coarctation of the aorta leading to early congestive heart failure, and their overall prognosis is poor. In the next largest group (Group II), patients have a subaortic ventricular septal defect and no pulmonary stenosis. Their presentation is similar to that of children with a large ventricular septal defect and pulmonary hypertension. In the smallest group (Group IV), the ventricular septal defect is uncommitted. Survivors in this group also clinically resemble children with a large ventricular septal defect and pulmonary hypertension. When present, coarctation of the aorta and severe mitral valve abnormalities greatly influence the prognosis in double outlet right ventricle. Although the prevalence of associated cardiac abnormalities is large, asplenia, polysplenia, chromosomal abnormalities and other congenital noncardiac abnormalities occur in only 12.5% of patients with double outlet right ventricle.     

Stenting of stenosed aortopulmonary collaterals and shunts for palliation of pulmonary atresia/ventricular septal defect.

Patients with unrepaired pulmonary artery atresia and ventricular septal defect (PA/VSD) depend on aortoplumonary collaterals and surgically created shunts for pulmonary blood flow. These vessels frequently develop stenoses with time, leading to hypoperfusion of lung segments and systemic hypoxemia. The purpose of this article is to describe catheter palliation of hypoxemic patients with PA/VSD who were not candidates for surgical repair. We present our experience with stent implantation for stenosis of aortopulmonary collaterals and shunts in these patients. Three patients with hypoplastic pulmonary arteries underwent stent placement in aortopulmonary collateral arteries (APCAs) or their shunts. Technical aspects of the interventional catheterization procedure are discussed in detail. Case 1 underwent placement of five stents in collateral vessels and one stent in the Blalock-Taussig shunt (BT) with dramatic increase in vessel size and improvement in saturations from 70% to 89%. Case 2 underwent placement of two overlapping stents in a collateral vessel with an increase in diameter of the collateral vessel from 2.3 to 6 mm and an improvement in saturation from 68% to 88%. Case 3 underwent placement of three overlapping stents in a BT shunt with an increase in diameter of the shunt from 2.2 to 6.6 mm and an improvement in saturation from 71% to 89%. All three patients had excellent clinical improvement and stable saturation at follow-up. Stent placement for maintaining patency of APCAs and aortopulmonary shunts is feasible and safe.     

Blood oxygen measurements in the assessment of intracardiac left to right shunts: A critical appraisal of methodology

The proper use of sequential diagnostic blood oxygen determinations for assessing left to right shunts requires a thorough understanding of the normal variability of blood oxygen measurements among the various right heart chambers and the influence of alterations in circulating hemoglobin levels and systemic blood flow. Oximetric measurements were obtained in 23 patients without a left to right shunt and compared with measurements obtained in 42 patients with a proved left to right shunt to examine the normal range of oxygen variability in blood samples from right heart chambers. The effect of fluctuations in hemoglobin levels was evaluated by comparing increases in percent oxygen saturation and oxygen content. Differences in percent saturation were found to be more useful than differences in oxygen content for detection of cardiac shunts. A mean difference of at least 7 percent oxygen saturation was found to be required for a firm diagnosis of a shunt at the atrial level, and 5 percent oxygen saturation for a shunt at the ventricular or great vessel level.The curvilinear relation between systemic blood flow and oxygen step-up in determining the pulmonary to systemic flow ($\text{Q}{}_{\mathrm{P}}\text{Q}{}_{\mathrm{S}}$) ratio was expressed in a series of equations and depicted by a three dimensional surface. Interventions such as exercise augment both systemic blood flow and oxygen step-up, resulting in a shift to a more steeply rising portion of the surface and a dramatic increase in shunt flow. The minimal left to right shunt detectable with oxlmetry is largely dependent on the level of systemic blood flow.     

Haemodynamics studies in patients with univentricular hearts.

The catheterization data including angiocardiography of 30 infants and children with different types of univentricular heart were used to study the influence of pulmonary and systemic flow as well as the position of the outlet chamber on systemic arterial saturation. All patients with normally connected great arteries displayed favourable streaming and differed significantly from those with 1-TGA as well as d-TGA, who showed varying streaming characteristics. Taking into account, however, the position of the outlet chamber, favourable streaming could be demonstrated to occur in most patients with TGA and lateral outlet chamber, and significantly less in patients with TGA and anterior outlet chamber. The influence of pulmonary and systemic flow on systemic arterial oxygen saturation was obvious only in the group with complete mixing and not in those patients, where arterial saturation was affected favourably or unfavourably by interindividual streaming differences. As expected, in patients with pulmonary stenosis the pulmonary flow was determined primarily by the degree of obstruction between ventricle and pulmonary artery. Reduced perfusion of the lungs in pulmonary stenosis does not result in increased perfusion of the systemic circulation. These results indicate that in patients with univentricular heart and ventriculo-arterial discordance, a pulmonary stenosis combined with lateral outlet chamber offers the most favourable outlook with regard to natural history.     

Two dimensional echocardiographic evaluation of mustard operation for d-transposition of the great arteries

Two dimensional sector scan echocardiography was used to evaluate the morphologic characteristics of the surgically revised atria in 17 patients with d-transposition of the great arteries who had undergone the Mustard operation. Echocardiographic imaging of the atria was obtained from various planar projections. Dimensional measurements of various segments of the systemic and pulmonary venous atria were obtained in each patient. Correlative hemodynamic, angiographic, postmortem and echocardiographic data showed that seven patients (Group I) had no structural abnormalities of the atria. These 7 patients served as controls for 10 other patients with structural abnormalities of the surgically created atria. One patient (Group II) showed stenosis of the junction of the superior vena cava and systemic venous atrium compared with findings in the control group. Three patients (Group III) had significantly reduced echocardiographic dimensions of the junction of the anterior and posterior segments of the pulmonary venous atrium. Six patients (Group IV) had increased echocardiographic dimensions of all components of the pulmonary venous atrium due to tricuspid regurgitation. These data show that qualitative and quantitative two dimensional sector echocardiography can reliably detect structural abnormalities of the surgically revised atria after the Mustard operation.     

The palliative Mustard operation: rationale and results.

The tendency toward development of severe pulmonary vascular obstructive disease in patients with complete transposition of the great arteries and associated large ventricular septal defect has been well documented. The physiologic consequence of this process is a significant reduction in intercirculatory mixing, resulting in increasingly severe levels of systemic arterial hypoxemia, compensatory polycythemia and an associated significant increase in symptoms. Data indicate that definitive surgical correction in patients with pulmonary arteriolar resistance of more than 10.0 units m2 is associated with a prohibitive operative mortality. However, the "palliative" Mustard operation (that is, intraatrial baffle repair, leaving the ventricular septal defect open) can be accomplished with relatively low risk and substantial hemodynamic benefits to the patient. It is erroneous to assume that the result of the operation will be a mere "reversal" of the preoperative systemic arterial and pulmonary arterial saturations, as shown by a review of the hemodynamic changes attributable to the operation. After the operation, systemic arterial saturations of 80 to 93 percent have been achieved, with a concomitant significant reduction in hemoglobin concentration, to a near normal level in some. Although the long-term prognosis in such patients is unknown, the reduction in symptoms and increase in exercise tolerance soon after operation are most gratifying.     

Preliminary experience with GORE-TEX grafting for right ventricle-pulmonary artery conduits

A consecutive series of 12 patients between the ages of 6 1/2 and 37 years underwent implantation of venous ventricle-pulmonary artery conduits. GORE-TEX material without prosthetic valves was used. Four patients had L-transposition of the great vessels with ventricular septal defect (VSD) and pulmonary stenosis; four had tetralogy of Fallot with pulmonary atresia; and one had double outlet right ventricle, pulmonary stenosis, and a complete form of A-V canal. Two patients had D-transposition of the great arteries, VSD, and pulmonary stenosis; and one patient had L-transposition of the great arteries and isolated pulmonary stenosis. All patients had low pulmonary resistance and pressures. The technique for implanting this noncrimped type of prosthesis is described in detail. Follow-up ranged from 2 months to 5 1/2 years. GORE-TEX offers a good choice of material for the construction of this type of conduit to prevent pseudointima formation and obstruction, which is often observed in woven Dacron grafts.     

Transcatheter left ventricular outflow tract stent placement in a low birth weight child with hypoplastic left ventricle,mitral atresia,transposition of the great arteries,ventricular septal defect and severe pulmonary stenosis

A baby boy, the first of triplets born at 33 weeks gestation weighing 1.88 kg, presented with neonatal cyanosis and was diagnosed with mitral atresia, hypoplastic left ventricle, ventricular septal defect, d‐transposition of the great arteries, severe pulmonary stenosis, and hypoplastic branch pulmonary arteries. He was treated with prostaglandin until seven weeks of age. The patent ductus arteriosus was curly Q and not suitable for stent placement. Cardiac catheterization was undertaken and using an antegrade approach, a Multi‐Link Ultra stent was implanted across the left ventricular outflow tract (LVOT) and inflated to 5 mm to improve antegrade pulmonary blood flow. This allowed reasonable pulmonary arterial growth to allow the patient undergo bidirectional Glenn shunt at five months of age. This first report of LVOT stenting in this setting may provide an alternative to placement of a systemic to pulmonary arterial shunt when ductal stenting is not possible. © 2013 Wiley Periodicals, Inc.     

Late right pulmonary artery stenosis after arterial switch operation in mirror image dextrocardia and situs inversus totalis

The operation of D-transposition of the great arteries is performed extremely rarely in patients with mirror image dextrocardia and situs inversus totalis. Therefore, it is not surprising that such unusual anatomy case presents problems with primary operation. We present a case of late right pulmonary artery stenosis after neonatal surgical anatomic correction of mirror image dextrocardia and situs inversus totalis.     

Stent implantation in right-sided patent ductus arteriosus to relieve severe cyanosis in adult patient with pulmonary atresia and ventricular septal defect.

Patients with unrepaired pulmonary atresia and ventricular septal defect may develop stenosis of collaterals or shunts to the pulmonary arteries leading to hypoperfusion of lungs and systemic hypoxemia. A 25-year-old female with pulmonary atresia and ventricular septal defect presented with progressively increasing cyanosis and exercise intolerance. A restrictive right-sided patent ductus arteriosus was identified as the main source of pulmonary blood flow. We report transcatheter implantation of a balloon-expandable stent across the stenosed duct to augment the pulmonary blood flow as a palliative management option. Patient had immediate improvement in arterial oxygen saturation from 66% to 85% with excellent clinical improvement and stable oxygen saturation on 8 months of follow-up.     

Balloon pulmonary valvotomy: palliation for cyanotic heart disease

Balloon pulmonary valvotomy was attempted in eight children with cyanotic congenital heart disease and pulmonic stenosis who were scheduled for a palliative procedure (shunt). In seven patients the balloon could be positioned across the pulmonary anulus, and valvotomy was performed. Five of the patients had tetralogy of Fallot with multiple levels of pulmonary outflow obstruction. For all patients in whom the balloon could be properly positioned the valvotomy was successful, as judged by arterial hemoglobin saturation, which increased from 72% +/- 5% to 83% +/- 5% (p less than .005). Valvotomy was followed by an immediate rise in mean pulmonary artery pressure (12.6 +/- 2.8 to 18.3 +/- 4.8 mm Hg, p less than 0.05) and a decline in hematocrit level at 2 months (54% +/- 5% to 47% +/- 4%, p less than 0.05). There was no mortality or complication from the valvotomy, and the need for a systemic to pulmonary artery shunt was eliminated in six of eight patients. Follow-up has ranged from 0.5 to 2.8 years. This trial indicates that balloon pulmonary valvotomy can be safely performed and is effective palliation in selected patients with cyanotic heart disease that is not suitable for primary repair. The increased pulmonary flow may improve oxygenation and growth of the pulmonary arteries without the need of a systemic to pulmonary artery shunt.     

The palliative Mustard operation for double outlet right ventricle or transposition of the great arteries associated with ventricular septal defect, pulmonary arterial hypertension, and pulmonary vascular obstructive disease. A report of eight patients.

Five patients with double outlet right ventricle, ventricular septal defect, pulmonary arterial hypertension and pulmonary vascular obstructive disease and three patients with complete d-transposition of the great arteries, ventricular septal defect, pulonary arterial hypertension and pulmonary vascular obstructive disease underwent an elective Mustard baffle operation. The ventricular septal defect was not closed. A large patent ductus arteriosus was divided in three patients. Seven of the eight patients are alive five to 32 months after surgery; one patient died 11 months after surgery. Cyanosis, dyspnea on exertion, and exercise limitation improved initially in all and has persisted in the survivors. In pre and postoperative hemodynamic studies in four patients, systemic arterial oxygen saturation and effective pulmonary blood flow increased from mean values of 70% to 90% and 1.7/min/m2 to 3.3 L/mon/m2, respectively. Absolute systemic and pulmonary flows, and pressures and resistances, were not significantly altered. Criteria for selection of patients with transposition of the great arteries of double outlet right ventricle who would benefit from a palliative Mustard procedure (Mustard atrial baffle without closure of the ventricular spetal defect) are: 1) severe symptoms; 2) pulmonary arteiral hypertension (75% systemic) with pulmonary vascular obstructive disease; and 3) pulmonary artieral oxygen saturation greater than systemic (ascending aorta) arterial oxygen saturation by approximately 10%.     

Early postoperative dysfunction of a modified Blalock-Taussig shunt: successful therapy with angioplasty and stent implantation in the subclavian artery

A newborn with pulmonary atresia with ventricular septal defect and transposition of the great arteries was palliated with a modified Blalock-Taussig shunt at 5 days of age. Three days postoperatively arterial oxygen saturations dropped significantly. Thrombosis of the shunt was suspected. Angiography revealed stenosis of the proximal subclavian artery related to the creation of the shunt. The patient was successfully treated with angioplasty and stent implantation into the stenotic subclavian artery. Follow-up angiography 3 months after stent deployment showed a completely patent subclavian artery and unobstructed blood flow across the modified Blalock-Taussig shunt.     

Echocardiographic assessment of left ventricular outflow tract in d-transposition of the great arteries

The left ventricular outflow tract in 38 patients (aged 0.3 to 13 years) with complete d-transposition of the great arteries, 31 with intraatrial (Mustard) repair, was quantitated with echocardiography, and the findings were correlated with hemodynamic and angiographic data. The left ventricular outflow tract (LVO) was measured on the echocardiogram as an anteroposterior dimension between the closure point on the mitral valve below the pulmonary arterial root (PA) and the left endocardial surface of the interventricular septum. This measurement was expressed as an LVO/PA ratio and on the basis of these measurements three groups were recognized.Group I consisted of 14 patients who had an unobstructed left ventricular outflow tract and no significant pressure differences between the pulmonary artery and left ventricle. In Group II, the 16 patients had evidence of dynamic obstruction and mild to moderate pressure differences between the pulmonary artery and left ventricle, characterized in the echocardiogram by LVO/PA ratios comparable with those of Group I, but with an abnormally prominent early posterior systolic septal bulge in the left ventricular outflow tract, abnormal systolic anterior motion of the mitral valve and coarse fluttering of the pulmonary valve. In Group III the eight patients had anatomically fixed stenosis of the left ventricular outflow tract and severe left ventricular outflow pressure gradients characterized in the echocardiogram by a reduced LVO/PA ratio and fine vibrations of the pulmonary valve. Angiographically discrete or long segmental narrowing of the left ventricular outflow tract correlated well with the echocardiographic data. Echocardiographic measurements of left ventricular posterior wall thickness also correlated well with the severity of left ventricular outflow stenosis in these three groups. The echocardiogram provides clinically useful quantitative and qualitative analysis of the left ventricular outflow tract in patients with complete transposition of the great arteries.     

Double outlet right ventricle: Hemodynamic and anatomic correlations

There are 16 possible variations of double outlet right ventricle with regard to interrelations of the great arteries and to location of the ventricular septal defect. In a series of 62 cases, approximately two thirds of patients had the great arteries in a side by side relation, and most (28 of 41) had the ventricular septal defect in a subaortic position. In double outlet right ventricle with malposition of the great arteries, the ventricular septal defect was either subpulmonary or subaortic. Four of the 13 patients with subpulmonary ventricular septal defect had a supracristal defect with side by side relation of the great arteries (Taussig-Bing anomaly), and 9 patients had malposition of the great arteries with an infracristal ventricular septal defect. In all patients with subpulmonary ventricular septal defect, pulmonary arterial oxygen saturation was greater than systemic arterial saturation regardless of the relation of the great arteries.Forty patients had subaortic ventricular septal defect. In 24 of these patients, including 7 with malposition of the great arteries, systemic arterial oxygen saturation was greater than pulmonary arterial saturation. However, in 9 patients (25 percent) the reverse was true, as seen in complete transposition of the great arteries and in Taussig-Bing anomaly. Thus, pulmonary arterial oxygen saturation greater than systemic arterial saturation is not reliable evidence of a Taussig-Bing anomaly. Of the 25 patients with such saturation, only 4 had the Taussig-Bing anomaly.