A reassessment of the anatomical features of multiple ventricular septal defects.

BACKGROUND: Over the course of time, new developments associated with the embryogenesis of the murine heart have served to clarify the developmental processes observed in the human heart. This evidence allows for the creation of a developmental framework for many congenital cardiac defects. AIMS: We aim to solidify the framework related to the categorization of both solitary and multiple ventricular septal defects. MATERIALS AND METHODS: Mice having genetic perturbation of the Furin enzyme have demonstrated perimembranous and juxta-arterial ventricular septal defects, permitting the inference to be made that these defects can co-exist with defects occurring within the apical muscular septum. RESULTS: Basis of developmental evidence, furthermore, all interventricular communications can be placed into one of three groups, namely those which are perimembranous, juxta-arterial, and muscular. All of the defects are described based on their borders as seen from the morphologically right ventricle. Our focus here will be on those defects within the muscular ventricular septum, recognizing that such defects can co-exist with those that are perimembranous. We discuss the differentiation of multiple discrete defects from those referred to as the "Swiss cheese" variant. CONCLUSIONS: As we show, appropriate surgical management requires an understanding of the specific terminology, as the surgical approach may differ depending on the combination of the individual defects. Data from the Society for Thoracic Surgeons revealed that both mortality and morbidity were increased in the setting of multiple as opposed to solitary ventricular septal defects.

A review of the therapeutic management of multiple ventricular septal defects.

BACKGROUND AND AIM: We showed in our anatomical review, ventricular septal defects existing as multiple entities can be considered in terms of three major subsets. We address here the diagnostic challenges, associated anomalies, the role and techniques of surgical instead of interventional closure, and the outcomes, including reinterventions, for each subset. METHODS: We reviewed 80 published investigations, noting radiographic findings, and the results of clinical imaging elucidating the location, number, size of septal defects, associated anomalies, and the effect of severe pulmonary hypertension. RESULTS: Overall, perioperative mortality for treatment of residual multiple defects has been cited to be between 0% and 14.2%, with morbidity estimated between 6% and 13%. Perioperative mortality is twice as high for perimembranous compared to muscular defects, with the need for reoperation being over four times higher. Perventricular hybrid approaches are useful for the closure of high anterior or apical defects. Overall, the results have been unsatisfactory. Pooled data reveals incidences between 2.8% and 45% for device-related adverse events. Currently, however, outcomes cannot be assessed on the basis of the different anatomical subsets. CONCLUSIONS: We have addressed the approaches, and the results, of therapeutic treatment in terms of coexisting discrete defects, the Swiss-cheese septum, and the arrangement in which a solitary apical muscular defect gives the impression of multiple defects when viewed from the right ventricular aspect. Treatment should vary according to the specific combination of defects.

Techniques and pitfalls of coronary arterial reimplantation in anatomical correction of transposition.

BACKGROUND AND AIM: We assessed the anatomical variations in coronary arterial patterns relative to the techniques of reimplantation in the setting of the arterial switch operation, relating the variations to influences on outcomes. METHODS: We reviewed pertinent published investigations, assessing events reported following varied surgical techniques for reimplantation of the coronary arteries in the setting of the arterial switch procedure. RESULTS: The prevalence of reported adverse events, subsequent to reimplantation, varied from 2% to 11%, with a bimodal presentation of high early and low late incidence. The intramural pattern continues to contribute to mortality, with some reports of 28% fatality. The presence of abnormal course relative to the arterial pedicles in the setting of single sinus origin was associated with a three-fold increase in mortality. Abnormal looping with bisinusal origin of arteries was not associated with increased risk. CONCLUSION: The techniques of transfer of the coronary arteries can be individually adapted to cater for the anatomical variations. Cardiac surgeons, therefore, need to be familiar with the myriad creative options available to achieve successful repair when there is challenging anatomy. Long-term follow-up will be required to affirm the superiority of any specific individual technique. Detailed multiplanar computed-tomographic scanning can now reveal all the variants, and elucidate the mechanisms of late complications. Coronary angioplasty or surgical revascularization may be considered in selected cases subsequent to the switch procedure.

Surgical management of lesions encountered in the setting of the retroaortic left brachiocephalic vein.

BACKGROUND AND AIM: Although the retroaortic left brachiocephalic vein in isolation is of no clinical importance, its recognition in the setting of associated lesions is important. We sought to address issues concerning the influence of isomerism, the establishment of diagnosis, and its importance in various surgical and interventional procedures. METHODS: A total of 80 published clinical and necropsy studies in the setting of a retroaortic left brachiocephalic vein described 250 patients. Clinical presentation, radiographic, ultrasonographic findings, contrast echocardiography, computed-tomographic angiocardiography, magnetic resonance imaging, and angiocardiography provided the diagnostic information prior to considering the surgical approach to the associated cardiac anomalies. RESULTS: Among 250 reported cases, three-quarters had associated congenitally malformed hearts. Of these 189 patients, all but seven had usual atrial arrangement. Right isomerism was reported in five patients and two patients having left isomerism. Almost two-thirds had tetralogy of Fallot or its variants, over four-fifths had malformations involving the outflow tract, two-thirds had a right aortic arch with two patients having a cervical aortic arch, and onepatient had double aortic arch. Various innovative individualized surgical procedures were employed with an overall perioperative mortality of 3.4%. CONCLUSIONS: Although the retroaortic left brachiocephalic vein is asymptomatic, its recognition during clinical investigation should raise the possibility of an association with other malformations, especially right aortic arch, ventricular septal defect, and anomalies of the outflow tracts. We submit that an increased appreciation of this venous anomaly may facilitate surgical planning, endovascular procedures, placement of central venous lines, and transvenous pacemakers.

Surgical management of divided atrial chambers.

BACKGROUND AND AIM: The morphological variations when one, or both, of the atrial chambers is subdivided, are many and varied. We sought to address clinical presentations, potentially misdiagnosed cases, diagnostic modalities, surgical approaches, and outcomes of this "family" of uncommon lesions. METHODS: A total of 193 published investigations were synthesized. Diagnostic information was provided by clinical presentation, and multimodality imaging studies. RESULTS: Almost three-quarters of patients with divided atrial chambers present during infancy with severe pulmonary hypertension and cardiac failure. Associated cardiac and extra-cardiac defects are present in between half and nine-tenths of cases. Acquired division of the left atrium has been reported after the Fontan operation, orthotopic cardiac transplantation, and complicated aortic valvar infective endocarditis. Surgery under cardiopulmonary bypass remains the definitive treatment. Balloon dilation may be considered in anatomically compatible variants in the setting of cardiac failure and pregnancy as a bridge todefinitive treatment. Overall, mortality has been cited between nil to 29%. Presentation during infancy, associated congenital anomalies, pulmonary hypertension, and surgery in the previous era, have been the reported causes of death. The operative survivors have long-term favourable outcomes, with near normal cardiac dimensions and low risk of recurrence. While asymptomatic patients with division of the right atrium do not need treatment, surgical resection of the dividing partition under cardiopulmonary bypass is recommended in symptomatic patients with complex anatomy, the spinnaker malformation, or associated cardiac anomalies. Balloon dilation may be considered in uncomplicated patients with less obstructive lesions. Hybrid intervention and endoscopic robotic correction also have been performed. CONCLUSIONS: Resection of the dividing shelf allows the survivors to regain near normal dimensions with a low risk of recurrence. We submit that an increased appreciation of the anatomic background to division of the atrial chambers will contribute to improved surgical management.

Surgical management of the scimitar syndrome.

BACKGROUND AND AIM: We sought to address the varied anatomical details, the diagnostic challenges, associated cardiopulmonary anomalies, the techniques, and outcomes of management, including re-interventions of scimitar syndrome. METHODS: A total of 92 published investigations of scimitar syndrome were reviewed. Diagnostic information was provided by clinical presentations, radiographic findings, transthoracic and transesophageal echocardiography, computed-tomographic angiography, magnetic resonance imaging, angiocardiography, and ventilation/perfusion scans. These investigations served to elucidate the origin, course, and termination of the scimitar vein, the intracardiac anatomy, the presence of associated defects, and the patterns of any accompanying pulmonary lesions prior to surgical intervention. RESULTS: Of the patients described, up to four-fifths presented during infancy, with cardiac failure, increased pulmonary flow, and pulmonary hypertension. Associated cardiac and extracardiac defects, particularly hypoplasia of the right lung, are present in up to three-quarters of cases. Overall operative mortality has been cited between 4.8% and 5.9%. Mortality was highest in patients with preoperative pulmonary hypertension, and those undergoing surgery in infancy. Despite timely surgical intervention, post-repair obstruction of the scimitar vein, intra-atrial baffle obstruction, or stenosis of the inferior caval vein were reported in up to two-thirds of cases. The venous obstruction could not be related to any particular surgical technique. On long term follow-up, one sixth of patients reported persistent dyspnoea and recurrent respiratory infections. CONCLUSIONS: Any infants presenting with heart failure, right-sided heart, and hypoplastic right lung should be evaluated to exclude the syndrome. An increased appreciation of variables will contribute to improved surgical management.

Can Echocardiographic Right Ventricular Function Parameters Predict Vasoactive Support Requirement After Tetralogy of Fallot Repair?

OBJECTIVE: To evaluate the role of echocardiographic right ventricular function parameters in predicting postoperative vasoactive inotrope requirement after tetralogy of Fallot repair. DESIGN: Prospective observational study. SETTING: A tertiary care hospital. PARTICIPANTS: Fifty-two children undergoing elective intracardiac repair. INTERVENTIONS: Comprehensive transesophageal echocardiography was performed before and after surgery. Fractional shortening, fractional area change, tricuspid annular plane systolic excursion (TAPSE), right ventricular myocardial performance index, tricuspid annular velocities (S', E', A'), and right ventricular global longitudinal strain and strain rate (RV Gls and RV Glsr) were measured. The ratio of peak systolic pressure of the right and left ventricles (Prv/lv) was measured directly from the surgical field pre- and post-repair. The inotrope requirement during first 24 postoperative hours was calculated using the mean Vasoactive-Inotropic Score (VIS). Pearson correlation analysis was used to study the relation between echocardiographic parameters and VIS as well as Prv/lv and VIS. Receiver operating characteristic analysis was used to study the predictive strength of parameters. MEASUREMENTS AND MAIN RESULTS: Among the measured parameters, both pre- and post-repair TAPSE had significant negative correlation with the mean VIS (p < 0.05). Both pre- and post-repair right ventricular myocardial performance index and S', E', A', RV Gls, RV Glsr, Prv/lv also had significant correlation with the mean VIS (p < 0.05). Of these, TAPSE, RV Gls, RV Glsr, and Prv/lv had significant predictive strength (p < 0.05) and reasonable sensitivity and specificity (area under the curve > 0.6) for predicting high mean VIS (VIS > 20). CONCLUSION: Tricuspid annular plane systolic excursion, RV Gls, RV Glsr, and Prv/lv could predict a postoperative high mean VIS with significant strength and reasonable sensitivity and specificity.

A Comparative Study of Histopathological Changes in the Ascending Aorta and the Risk Factors Related to Histopathological Conditions and Aortic Dilatation in Patients With Tetralogy of Fallot and a Functionally Univentricular Heart.

BACKGROUND: The purposes of this study were to prospectively evaluate the histologic characteristics of the aortic wall of patients undergoing univentricular type of repair and compare the same with the findings observed in patients undergoing intracardiac repair of tetralogy of Fallot (TOF). PATIENTS AND METHODS: Operatively excised full-thickness aortic wall tissue from 99 consecutive patients undergoing either intracardiac repair of TOF (group I; n=42) or univentricular repair (group II; n=57) were studied by light microscopy. Age at operation was 13 months to 28 years (mean 99.97±73.21months) for group I and 9 months to 25 years (mean 79.52±60.09) months for group II patients. RESULTS: Dilatation of the ascending aorta was present in 85.7% patients with TOF and 91.2% patients with a univentricular heart. Seventeen (17.2%) aortic specimens were histologically normal and were used as normal controls (group I, n=5; group II, n=12). A lamellar count of less than 60 was associated with a sensitivity of 97.2% and a specificity of 66.7% in patients undergoing repair of TOF and a sensitivity of 84.6% and a specificity of 80% in patients undergoing univentricular type of repairs respectively. Patients undergoing intracardiac repair of TOF and those undergoing univentricular repair exhibited 23.67 times (15.91-147.40) and 8.48 times (3.62-15.84) increased risk of aortic dilatation respectively. CONCLUSIONS: Our findings indicate the existence of significant elastic fragmentation, muscle disarray, medionecrosis and fibrosis involving the ascending aortic media in patients with a functionally univentricular heart and dilated aorta. These histopathological changes are similar to those encountered in patients with TOF and dilated aorta.

Left Bidirectional Cavopulmonary Connection in Raghib's Defect: Report of 5 Cases and Review of Literature.

We report five male patients aged 3, 6, 8, 10, and 15 years, respectively, undergoing left bidirectional cavopulmonary connection and concomitant Dacron patch closure of the atrial septal defect for Raghib's defect with persistent left superior vena cava. The circulation was successfully corrected. This extracardiac procedure uses only autogenous tissues having growth potential, reduces myocardial ischemia, and avoids later baffle deterioration with pulmonary venous obstruction associated with intra-atrial baffling procedures. A wider appreciation and application of this management modality is warranted.

Ivabradine Versus Amiodarone in the Management of Postoperative Junctional Ectopic Tachycardia: A Randomized, Open-Label, Noninferiority Study.

OBJECTIVES: This study sought to compare the efficacy of ivabradine and amiodarone in the management of postoperative junctional ectopic tachycardia (JET) after cardiac surgery in children. BACKGROUND: JET is a serious arrhythmia occurring in children after cardiac surgery and requires aggressive management. Amiodarone has been conventionally used in its treatment. Recent studies have reported the utility of ivabradine in this regard. METHODS: In this open-label randomized controlled trial, 94 children (age ≤18 years) who developed postoperative JET were allocated to receive either amiodarone or ivabradine. The primary endpoint was restoration of normal sinus rhythm. RESULTS: Sinus rhythm was achieved in 43 out of the 46 patients (93.5%) in the amiodarone group and 46 out of the 48 patients (95.8%) in the ivabradine group (mean difference of treatment effect: 2.3%; 95% confidence interval: -6.7% to 11.5%). The median (interquartile range) time taken to achieve sinus rhythm conversion was similar in both the groups: 21.5 (17-30.2) hours versus 22 (13.4-38.5) hours (p = 0.36)]. The time taken to rate control of JET was significantly less in the amiodarone group: median 7.0 (5.5-9.5) hours versus 8.0 (5.8-10.8) hours (p = 0.02)]. No drug-related adverse events were observed in the ivabradine group. CONCLUSIONS: Oral ivabradine is not inferior to intravenous amiodarone in converting postoperative JET to sinus rhythm. There was no difference in time taken to sinus rhythm conversion between the groups, although the rate control was earlier in patients who received amiodarone. Monotherapy with ivabradine may be considered as an alternative to amiodarone in the management of postoperative JET. (Comparison of Two Drugs, Ivabradine and Amiodarone, in the Management of Junctional Ectopic Tachycardia, an Abnormality in Cardiac Rhythm in Patients Under 18 years Who Undergo Cardiac Surgery: CTRI/2018/08/015182).

Congenital left atrial appendage aneurysm: a case report and brief review of literature.

A 28-year-old woman with congenital aneurysm of the left atrial appendage was successfully treated by aneurysmectomy and is reported for its rarity. The exact diagnosis is relatively easy to make by contrast echocardiography, magnetic resonance imaging, and/or computerised tomographic angiography, provided the possibility is entertained. Because of supraventricular arrhythmias and systemic thromboembolism, surgical resection was deemed the best curative option to avoid further episodes and recurrence. Published reports detailing the diagnostic evaluation and surgical management for congenital left atrial appendage aneurysm are also discussed.

Successful lobectomy for pulmonary arteriovenous malformation causing recurrent massive haemoptysis.

A 6-year-old child with pulmonary arteriovenous malformation (PAVM) of the lower lobe of left lung was successfully treated by left lower lobectomy and the case is reported for its rarity. The exact diagnosis is relatively easy to make by contrast echocardiography and pulmonary angiocardiography, provided the possibility is entertained. Because of recurrent episodes of massive haemoptysis from a single pulmonary lobe, surgical resection was deemed the best curative option to avoid further episodes and recurrence. Published reports detailing coil embolisation therapy for PAVMs are also discussed.

Serial radionuclide angiographic assessment of left ventricular ejection fraction and regional wall motion after mitral valve replacement in patients with rheumatic disease.

BACKGROUND: This study was designed to prospectively investigate the effects of total or partial chordal-sparing and chordal-nonsparing mitral valve replacement (MVR) procedures on regional and global ventricular function in a rheumatic population using sequential multiple-gated acquisition scan. METHODS: One hundred five consecutive patients undergoing different techniques of chordal preservation procedures during MVR are included in this prospective study. Fifteen patients had complete excision of the chordopapillary apparatus (group 1), 34 had total chordal preservation (group 2), and 56 had preservation of the posterior chordopapillary apparatus (group 3). Radionuclide-derived left ventricular ejection fraction (LVEF) and regional wall motion (RWM) studies on 99 survivors were performed preoperatively, at discharge, at 1 year, and at 2 years. RESULTS: At discharge, there was a decline in LVEF in all the 3 groups. Statistically significant improvement in ejection fraction occurred in the chordal preservation groups (2 and 3) (P < .05) as compared with the nonchordal group immediately and late postoperatively. Only the total chordal group (2) demonstrated complete recovery of LVEF by 2 years postoperatively. Significant and persistent RWM abnormalities were noted in both the nonchordal and posterior chordal groups. CONCLUSIONS: We conclude that complete retention of the chordopapillary apparatus during MVR provides superior results compared with nonchordal and partial chordal preservation in terms of preservation of LVEF and reduced incidence of abnormal postoperative RWM.

Myocardial injury in coronary artery bypass grafting: On-pump versus off-pump comparison by measuring heart-type fatty-acid-binding protein release.

This prospective study uses heart-type fatty-acid-binding protein (hFABP) and creatine kinase-MB (CK-MB) release to compare myocardial injury in on-pump versus off-pump coronary artery bypass grafting (CABG). Fifty patients were randomly assigned to on-pump or off-pump CABG. The hFABP and CK-MB concentrations were measured in serial venous blood samples drawn before heparinization in both groups and after aortic unclamping at 1, 2, 4, 8, 24, 48, and 72 hours in the on-pump group. In the off-pump group, samples were taken after the last distal anastomosis at the same time intervals as in the on-pump group. The total amount of hFABP and CK-MB released was significantly higher in the on-pump than in the off-pump group (hFABP = 100.43 +/- 77.63 vs 3.94 +/- 0.36 ng/mL, P < 0.0001; CK-MB = 33.33 +/- 3.81 vs 28.65 +/- 3.91 log units, P < 0.001). In all patients, hFABP levels peaked as early as 1 hour after declamping (on-pump group) or 2 hours after the last distal anastomosis (off-pump group), whereas CK-MB peaked only at 4 hours after declamping (on-pump group) or 24 hours after the last distal anastomosis (off-pump group). The lower release of hFABP and CK-MB in the off-pump CABG group indicates that on-pump CABG with cardioplegic arrest causes more myocardial damage than does off-pump CABG. Heart-type fatty-acid-binding protein is a more rapid marker of perioperative myocardial damage, peaks earlier than CK-MB, and may predict the requirement for intensive monitoring for postoperative myocardial infarction.

Twenty-eight-year survival of stent-mounted aortic homograft in the mitral position: case report.

The case is presented of a long-term survivor after bioprosthetic valve implantation. A stent-mounted aortic homograft had been implanted in the mitral position, and survived for 28 years before being removed due to a tear in the base of leaflet, resulting in mitral regurgitation. The technique was discontinued in the mid- 1970s following reports of detachment of aortic valve cusps from the stent. The current case report may rekindle interest in the method, and also lead to an investigation of the factors that influence structural deterioration of bioprosthetic valves.

Congestive heart failure in unoperated tetralogy of Fallot: can hypoxia be a cause?

A 10-year-old boy with tetralogy of Fallot and congestive heart failure underwent a right-sided modified Blalock-Taussig anastomosis because of severe biventricular dysfunction and repeated hypercyanotic spells. Postoperatively, there was improvement in systemic oxygen saturation and myocardial function. We postulate that congestive heart failure occurred because of severe myocardial hypoxia and its elimination resulted in markedly improved cardiac performance.

Congenital Erythropoietic Porphyria With Calcific Constrictive Pericarditis: A Case Report and Brief Review of Literature.

An 18-year-old boy with congenital erythropoietic porphyria and calcific constrictive pericarditis underwent total pericardiectomy. The cause of pericardial calcification could be deposition of porphyrins in the pericardium. Surgical importance of this rare condition is highlighted.

Right Coronary Artery to Pulmonary Arterial Fistula Associated With Tetralogy of Fallot: A Case Report and Review of Literature.

A 16-year-old boy with tetralogy of Fallot (TOF), pulmonary stenosis, and coronary artery to pulmonary arterial fistulous communication arising from the proximal right coronary artery is reported for its rarity. The surgical importance of this anomaly is highlighted. The diagnosis should be borne in cases of TOF, with echocardiographic demonstration of severe right ventricular outflow tract obstruction without a corresponding degree of systemic arterial desaturation.

Ventricular septal defect with congenital mitral valve disease: long-term results of corrective surgery.

BACKGROUND: A retrospective analysis of the mortality, morbidity and long-term follow-up of patients undergoing corrective surgery for ventricular septal defect and congenital mitral valve disease is presented. METHODS AND RESULTS: Between January 1991 and December 2000, 69 consecutive patients aged 2 months to 45 years (median 18 months) underwent repair of ventricular septal defect and associated mitral valve disease. In 52 patients (75%), the ventricular septal defects were located in the perimembranous and subarterial area. Forty-six patients had congenital mitral incompetence and 23 had congenital mitral stenosis. The ventricular septal defect was repaired through the right atrium in all. Sixty-five patients underwent reconstruction of the mitral valve and 4 underwent primary mitral valve replacement. Another 4 patients underwent mitral valve replacement after a failed repair. Associated procedures included: patent ductus arteriosus ligation (n=12), aortic valve replacement (n=6), coarctation repair (n=13), interrupted aortic arch repair (n=1), atrial septal defect closure (n=17) and Takeuchi repair (n=1). There were 6 early deaths (8.6%). Three deaths were due to pulmonary arterial hypertensive crisis and one due to residual mitral stenosis. One death was due to intractable congestive heart failure. Another patient died due to persistent low cardiac output. Follow-up ranged from 6 months to 120 months (mean 64.4+/-33.6 months). Reoperation was required in 22 patients, mainly for recurrent/residual mitral valve dysfunction or hemodynamically significant left ventricular outflow tract obstruction. There were 4 late deaths, 2 due to residual mitral stenosis and the other 2 as a result of a thrombosed prosthetic valve. At 10 years, the actuarial survival rate was 850+/-5.0%, and freedom from reoperation was 45%+/-10.0%. CONCLUSIONS: Reconstruction of the mitral valve along with closure of VSD is possible in most cases. However, careful follow-up is recommended to detect changes in the mitral valve status over a course of time.

Surgical outcome of staged univentricular-type repairs for patients with univentricular physiology and pulmonary hypertension.

BACKGROUND: There is no consensus about the most appropriate limits of pulmonary artery pressure and vascular resistance in case of patients undergoing univentricular or one and one-half ventricular repair. This study was conducted to analyze the mortality and morbidity of a heterogenous group of patients with a functionally univentricular heart and pulmonary artery hypertension, undergoing pulmonary artery banding followed by univentricular-type repairs. METHODS AND RESULTS: Out of 254 patients undergoing pulmonary artery banding for a functionally univentricular heart with increased pulmonary blood flow, 148 patients underwent definitive second stage surgery. Post-band hemodynamic evaluation revealed persistently high pulmonary artery pressure (> 18 mmHg), and pulmonary vascular resistance (>2.0 Woods units/m2) in 78.3% patients. Sixteen patients with moderate right ventricular hypoplasia were given a one and one-half ventricle repair (Group I), 82 patients a bidirectional Glenn connection (Group II), and 50 patients a fenestrated total cavopulmonary connection (Group III). The overall mortality following second stage surgery for the high pulmonary artery pressure group (n=116) was 30.17%, while none of the low pulmonary artery pressure group died (p=0.0009). Pulmonary hypertensive crises and/or systemic desaturation were the main causes of death at second stage repair. All mortality occurred in patients with mean pulmonary artery pressure > 18 mmHg and pulmonary vascular resistance > 3.5 Woods units/m2. Survivors from this group had persistent morbidity in the form of superior vena caval syndrome and suboptimal oxygen saturation (70-75%). CONCLUSIONS: It is advisable not to proceed with definitive second stage repair if post-pulmonary artery banding mean pulmonary artery pressure is over 25 mmHg and pulmonary vascular resistance exceeds 4.0 Woods units/m2. These patients may possibly be deemed to have undergone definitive palliation during their pulmonary artery banding.