Central Pulmonary Artery Growth Research Articles

Evaluation of the Growth of Central Pulmonary Arteries Following Patent Ductus Arteriosus Stenting in Patients with Duct Dependent Pulmonary Circulation

Pulmonary arteries' (PAs) growth can be promoted by stenting of patent ductus arteriosus (PDA). This may result in better angle between the PDA and the PAs, allowing improved growth. In this study, we sought to evaluate the effect of PDA stenting on the growth of the pulmonary arteries by comparing their dimensions pre-stenting to their dimensions in the pre-second stage operations in patients with congenital heart diseases-duct-dependent pulmonary (CHD-DDP) circulation. Between January 2015 and December 2016, 58 neonates with CHD-DDP circulation underwent transcatheter PDA stenting and had evaluation of PAs growth before the second stage. Various parameters [Pre-branching right and left pulmonary artery (RPA, LPA) diameters, their Z scores, LPA/RPA ratio, McGoon's ratio and Nakata index] were recorded and compared pre-stenting and pre-second stage. The evaluation was done using catheterization or multislice computed tomography (MSCT). PDA stenting was successful in 49 patients out of 58 (84.5%) patients with an age of 13.5 ± 10.4days and a weight of 2.9 ± 0.5kg. Twenty-two (44.9%) patients had complex CHD-DDP, 14 (28.6%) patients had PA/IVS and 13 (26.5%) patients had PA/VSD. Pre-second stage RPA, LPA diameters and their Z scores increased significantly (RPA increased from 0.36 ± 0.05cm to 0.60 ± 0.11cm, P < 0.001, RPA Z-score increased from -1.29 ± 0.91 to 0.81 ± 0.18, P < 0.001; LPA increased from 0.34 ± 0.06cm to 0.58 ± 0.10cm, P < 0.001, LPA Z-score increased from -1.17 ± 0.86 to 0.97 ± 0.48, P < 0.001). McGoon's ratio increased significantly from 1.20 ± 0.11 to 1.61 ± 0.15 (P < 0.001). Nakata index increased from 105.94 ± 33.53 to 183.48 ± 40.58 mm2/m2 (P < 0.001). However, LPA/RPA ratio did not change (0.96 ± 0.05 and 0.98 ± 0.16, P = 0.288). PDA stenting is effective in promoting the global and the individual pulmonary artery growth in congenital heart diseases with duct-dependent pulmonary circulation. In this study, we presented our experience with this approach in 2 tertiary care centers in the DELTA region of Egypt. PDA stenting, generally, showed symmetric growth of the pulmonary arteries with comparable results to the international figures.

Bilateral bidirectional Glenn: outcome of off-pump technique.

Off-pump bilateral bidirectional Glenn (b-BDG) poses a surgical challenge and may add complexity to the postoperative outcome especially regarding uniformity of the anastomosis and central pulmonary artery growth. Herein, we report early- and mid-term outcomes after off-pump b-BDG without using superior vena cava decompression techniques. Ninety-seven consecutive patients, between 2009 and 2014, were included in this prospective study. All patients had complete pre- and postoperative clinical and detailed neurological assessments. Diagnosis and follow-up were done by echocardiography and cardiac catheterization for assessment of pulmonary artery anatomically and haemodynamically. Median follow-up period was 3.5 years. Perioperative variables, clinical outcome, morbidity, mortality and follow-up data were recorded. Hypoplastic right ventricle was present in 52 cases (53.6%) and hypoplastic left ventricle was present in 45 cases (46.4%). Mean superior vena cava pressure on clamping was 21.49 ± 3.04 mmHg. Mean total clamping time was 23.11 ± 3.44 min. Mean oxygen saturation increased from preoperative 69.22 ± 6.01% to 83.66 ± 3.97% after b-BDG construction (P-value ≤ 0.0001). The Nakata index increased from 288.47 ± 28.66 mm2/m2 to 303.64 ± 26.85mm2/m2 on follow-up (P-value ≤ 0.05). In-hospital mortality was 4 patients (4.1%) due to low-cardiac output. There were chylothorax in 9 patients (9.3%) and convulsions in 4 patients (4.1%) who were treated conservatively. Off-pump b-BDG can be conducted safely, with a uniform anastomosis that allows a good central pulmonary artery growth for subsequent Fontan completion. Moreover, avoiding the use of cardiopulmonary bypass is more economic and less hazardous.

Impact of Bilateral Superior Venae Cavae on Outcome of Staged Fontan Procedure

The presence of bilateral superior venae cavae may add complexity to the performance of a bidirectional Glenn procedure (BDG). Stagnation of blood flow between the two cavopulmonary anastomoses may increase the risk of thrombosis and impair central pulmonary artery growth. Forty patients underwent BDG from January 2004 to April 2011. The cohort was divided into two groups: those receiving bilateral BDG (b-BDG, n= 13) and those receiving unilateral BDG (u-BDG, n= 27). Operative, angiographic, and follow-up data were analyzed retrospectively. None of the patients experienced thrombosis. There was no difference in actuarial survival rate (u-BDG vs b-BDG, 100% vs 92% at 5 years, p= 0.15). On follow-up angiography, no difference in central pulmonary artery index was noted (78.4 ± 45.5 vs 60.4 ± 32.1, p= 0.24). Central pulmonary artery stenosis was detected in 6 patients (4with u-BDG and 2 with b-BDG), 4 of whom (2 from eachgroup) underwent balloon pulmonary artery plasty before the Fontan procedure. There was no difference in freedomfrom reintervention for central pulmonary artery stenosis(93% vs 85% at 1 year, p= 0.59). The rate ofFontancompletion was comparable between groups, with similaroperative variables and satisfactory outcomes. Bilateral BDG did not increase the risks of thrombosis and central pulmonary artery hypoplasia and can be performed safely without altering the outcome of the Fontan procedure.

Growth of Diminutive Central Pulmonary Arteries After Right Ventricle to Pulmonary Artery Homograft Implantation

The management of tetralogy of Fallot, pulmonary atresia, and major aortopulmonary collateral arteries is controversial because of the wide variability of pulmonary artery (PA) and major aortopulmonary collateral arteries morphology. Several different staged strategies have been used to promote growth of diminutive PA branches. We have preferred a right ventricular (RV)-PA homograft for symmetrical growth of the central PA branches. In this study we evaluated the success of this strategy. Between 2006 and 2012, 23 patients with pulmonary atresia and diminutive PAs underwent RV-PA homograft implantation. Median age was 2 months (range, 4 days to 18 months), and median body weight was 5.1 kg (range, 1.7 to 8.5 kg). The type of homograft was aortic in 8, pulmonary in 6, and femoral vein in 9. The mean diameter of the homograft was 10.5 mm (range, 6 to 16 mm). All procedures were performed on cardiopulmonary bypass. The PA diameter was measured at the time of the operation and subsequent catheterization. The median size of the branch PA was 2.1 mm. In the 18 patients who had serial assessment of PA size, the right PA increased by 307% ± 184%, the left PA increased by 283% ± 139%, and the Nakata index increased from 28.8 ± 20.1 mm(2)/m(2) to 253 ± 96 mm(2)/m(2) during a median period of 347 days (range, 44 to 1,520 days). The PA growth ratio (PA growth in mm/mo) was similar between the right PA (0.42 ± 0.46 mm/mo) and the left PA (0.43 ± 0.47 mm/mo). There was no acute conduit failure. Seventeen patients required 28 percutaneous interventionsfor embolization of an aortopulmonary collateral or stenosis of the conduit or PA. There were no hospital deaths. Three patients died late after other procedures during a mean follow-up of 44.7 months. Twenty patients (87%) have undergone complete repair to date. RV-PA homograft implantation can be performed in neonates and infants with minimal risk of acute occlusion. The RV-PA homograft promotes rapid and balanced growth of central pulmonary arteries leading to complete repair in most patients.

Size of the right ventricle-to-pulmonary artery conduit impacts mid-term outcome after the Norwood procedure in patients weighing less than 3 kg

The optimal shunt size for patients who have the Norwood operation with a right ventricle-to-pulmonary artery conduit is controversial. The goal of this study is to compare outcomes of 2 shunt sizes in this population. Between 2002 and 2010, 75 consecutive patients diagnosed with hypoplastic left heart syndrome and its variants underwent the Norwood procedure with a right ventricle-to-pulmonary artery conduit. The outcomes of 20 neonates weighing <3 kg were analyzed. The cumulative 30-day stage 1 survival [corrected] was 97% (95% confidence interval, 88%-99%) for all patients (73/75), 20 of whom weighed <3 kg. Nine patients had a 6-mm (group 1) and 11 patients had a 5-mm (group 2) right ventricle-to-pulmonary artery conduit. Thirty-day stage 1 survival was 88% (8/9) in group 1 and 90% (10/11) in group 2 (P = .88). The central pulmonary artery confluence size at prebidirectional cavopulmonary shunt catheterization was 4.5 ± 1.2 mm in group 1 and 2.5 ± 1.0 mm in group 2 (P = .009). The mean transpulmonary gradient was higher in group 2 (7.8 ± 3.1 mm Hg vs 4.2 ± 1.9 mm Hg; P = .036). The incidence of pulmonary artery intervention was 16% (1/7) in group 1 and 75% (6/8) in group 2 (P = .030). Survival rate at 6 months was 66% (6/9) in group 1 and 70% (7/10) in group 2 (P = .89). Use of a 6-mm right ventricle-to-pulmonary artery conduit showed better central pulmonary artery growth and less need for pulmonary artery intervention in the authors' experience.

Impact of evolving strategy on clinical outcomes and central pulmonary artery growth in patients with bilateral superior vena cava undergoing a bilateral bidirectional cavopulmonary shunt

We reported a high incidence of thrombosis, central pulmonary artery hypoplasia, and mortality for bilateral bidirectional cavopulmonary shunts. We hypothesized that technical modifications in the cavopulmonary anastomosis and anticoagulation would limit thrombus and central pulmonary artery hypoplasia, and thereby improve outcomes. Sixty-one patients (median age, 8.4 months; weight, 6.6 kg) underwent bilateral bidirectional cavopulmonary shunt from 1990 to 2007. The cohort was divided into 2 groups: 1) the conventional group (1990-1999, n = 37) and 2) the V-shaped group, with a hemi-Fontan or modification in which the cavae were anastomosed to the pulmonary artery adjacent to each other so they formed the appearance of a V (1999-2007, n = 24). Central and branch pulmonary artery growth, survival, and reinterventions were determined. The pre-Fontan study showed equivalent superior venae cavae and Nakata indices. The central pulmonary artery index and central pulmonary artery/Nakata index ratio were significantly higher in the V-shaped group (P < .05). There were no differences in freedom from death or transplant (conventional 69% vs V-shaped 75% at 3 years, P = .5), and a nonsignificant trend toward improving freedom from reinterventions (63% vs 81% at 3 years, P = .15) and thrombosis (82% vs 95% at 1 year, P = .11) was observed in the V-shaped group. Multivariate analysis showed anastomotic strategy, low saturation, and thrombosis were predictors for death. Anastomotic strategy, lack of anticoagulation, thrombosis, and small superior venae cavae were predictors for reintervention (P < .05). Predictors for thrombus included small superior venae cavae, Nakata index, and low saturation (P < .03). Surgical modifications for bilateral bidirectional cavopulmonary shunts were associated with the larger central pulmonary artery size. Lack of anticoagulation and anastomotic strategy affected reintervention. Anastomotic strategy and postoperative thrombus affected mortality.

Melbourne Shunt Promotes Growth of Diminutive Central Pulmonary Arteries in Patients With Pulmonary Atresia, Ventricular Septal Defect, and Systemic-to-Pulmonary Collateral Arteries

We manage patients with pulmonary atresia, ventricular septal defect, major systemic-to-pulmonary collateral arteries, and diminutive central pulmonary arteries with a staged approach. The first procedure is a central end-to-side aortopulmonary shunt (Melbourne shunt) intended to cause growth and development of the central pulmonary arteries. We subsequently measured central pulmonary artery growth after Melbourne shunt. Forty consecutive patients were followed after Melbourne shunt. The maximum pulmonary artery diameter was measured at the time of surgery and at subsequent catheterizations or surgery. Median pulmonary artery size at surgery was 2 mm. The median pulmonary artery diameter was 5.5 mm at first assessment (median, 6.35 months) and 7 mm at most recent assessment (19.7 months). Mean modified Nakata index increased from 27 mm(2)/m(2) at surgery to 138 mm(2)/m(2) at first assessment, and 176 mm(2)/m(2) at final assessment. There was one acute shunt failure from anastomotic stenosis. Thirteen patients (32.5%) required 21 percutaneous interventions. There were 4 deaths during a median follow-up of 68 months. At the time of complete repair (n = 25) all patients required pulmonary artery augmentation, and 8 are in various stages of palliation. The remaining patients are considered not reparable owing to irreversible pulmonary hypertension (n = 4) or have required fenestration of ventricular septal defect after complete repair (n = 2). Melbourne shunt promotes modest growth of central pulmonary arteries leading to complete repair in the majority of patients. There is considerable need for further interventions in these patients to augment the size of the pulmonary arteries.

Pulmonary atresia with ventricular septal defects and major aortopulmonary collateral arteries: Unifocalization brings no long-term benefits

We sought to evaluate the contribution of unifocalization procedures in the management of patients with pulmonary atresia, ventricular septal defect, and major aortopulmonary collateral arteries. From 1975 through 1995, 82 consecutive patients were entered in a multistage approach and had 189 sternotomies and thoracotomies to perform 119 shunts, 130 major aortopulmonary collateral artery transplantations, and 76 major aortopulmonary collateral artery ligations. The serial angiographies and the follow-up of these patients were reviewed. The concurrent follow-up rate was 80%. The hospital mortality of the preliminary procedures was 4% (7/189). Fifty-three (65%) patients had a complete repair. The hospital mortality of the repair was 8% (4/53), and 9 late deaths occurred after repair, all of which were cardiac related. The overall survival of all patients to the age of 30 years was 58% +/- 7%. Survival 12 years after complete repair was 51% +/- 14%. On angiography, central shunts promoted growth of central pulmonary arteries in all cases (29 patients). Sixty unifocalized major aortopulmonary collateral arteries were identified in 31 patients. After a mean of 3.2 +/- 4 years, 26 thrombosed, and 12 presented with a stenosis of greater than 50%. Serial measurements of 29 major aortopulmonary collateral arteries showed no signs of growth (P = .25). Long-term survival into adulthood of patients with pulmonary atresia, ventricular septal defect, and major aortopulmonary collateral arteries has been achieved with a multistage approach. However, late survival depends exclusively on the growth of the native pulmonary circulation. The few unifocalized major aortopulmonary collateral arteries that did not thrombose failed to grow.

The RV–PA conduit stimulates better growth of the pulmonary arteries in hypoplastic left heart syndrome☆

This retrospective study compared the size of the central pulmonary arteries in patients with hypoplastic left heart syndrome (HLHS) following either a classical Norwood or Norwood procedure with a right ventricle to pulmonary artery (RV-PA) conduit. Between May 2001 and May 2003, 30 patients with HLHS underwent cardiac catheterization prior to stage II palliation. Patients were initially palliated with a classical Norwood (Classical group, n=18) or Norwood procedure with RV-PA conduit (RV-PA group; n=12). Indexed maximum and minimum diameters of the LPA and RPA were measured using the McGoon ratio. Cardiac catheterisation was performed at a median age of 4.0 months. There was no difference in the time interval to catheterisation (P=0.13), Qp:Qs (P=0.41) or median haemoglobin (P=0.42) between the groups. The combined PA diameter was larger in the RV-PA group (B) than the classical group (A) (1.99+/-0.38 versus 1.63+/-0.29, P<0.05). There were marked differences in the relative size of the pulmonary arteries between the two groups. In RV-PA patients, the LPA and RPA sizes were comparable (0.99+/-0.22 versus 1.00+/-0.31, P=1.00) whereas, in the classical group, the LPA was smaller than the RPA (0.75+/-0.15 versus 0.88+/-0.17, P<0.05). Both techniques were also associated with discrete PA stenoses at the site of shunt insertion. Stenoses were more severe in RV-PA group (RV-PA), causing a 42+/-16% reduction in the combined PA diameter compared with a 28+/-18% reduction in Classical group (classical) (P<0.05). The Norwood procedure with RV-PA conduit is associated with better and more evenly distributed central pulmonary artery growth. Nevertheless, it is also associated with central PA stenoses, which may require subsequent reconstruction.

Invited commentary

Invited commentary

Modified hemi-Fontan operation: An alternative definitive palliation for high-risk patients

We conceptualized that by adding small amounts of prograde pulmonary blood flow to the hemi-Fontan operation, or bidirectional Glenn procedure, this modified hemi-Fontan operation could be safely done at an early age, with better oxygenation, and with less potential for pulmonary arteriovenous fistulae. Since April 1992 the hemi-Fontan operation was modified by adding some prograde flow through the native pulmonary artery in 10 high-risk infants, either by leaving the critical subpulmonary stenosis untreated (n = 6) or by tightening a previously placed pulmonary artery band (n = 4). All other sources of pulmonary blood flow were interrupted. Patients were 4 to 23 months old (3.8 to 10.3 kg). Diagnoses included isolated dextrocardia with single ventricle (3) and polysplenia syndrome (2). Cardiopulmonary bypass was needed in 5 patients. There were no hospital deaths. Mean postoperative intensive care unit stay was 2 days, and 9 of 10 patients were discharged within 7 days of operation. One 4-month-old infant with Down's syndrome survived postoperative takedown of the hemi-Fontan repair after pneumonia and caval thrombosis developed. Eight patients are currently asymptomatic receiving minimal modification, and oxygen saturations range from 84% to 93%. Adding small volumes of prograde pulmonary blood flow to the hemi-Fontan operation is safe, provides improved oxygenation, may encourage growth of central pulmonary arteries, and represent an alternative definitive palliation for high-risk Fontan candidates.

Central pulmonary artery growth patterns after the bidirectional Glenn procedure

The changes in pulmonary artery size and hemodynamics in 30 patients with univentricular cardiac anatomy were examined before and after bidirectional Glenn procedures done between October 1989 and February 1992. Serial angiographic and hemodynamic examinations before and 17.6 +/- 1.6 months after bidirectional Glenn procedures were compared. At the follow-up study there was no significant change in diameter of the pulmonary artery ipsilateral to the bidirectional Glenn shunt, however, a significant decrease was noted in the diameter of the pulmonary artery contralateral to the bidirectional Glenn shunt (p = 0.04). There was also a 32% decrease in the Nakata index of total cross-sectional pulmonary artery area after the bidirectional Glenn procedure (p = 0.004). Total pulmonary blood flow and mean pulmonary artery pressure had decreased, and arterial oxygen saturation had increased at follow-up. These changes, however, did not correlate with the observed changes in pulmonary artery size. By linear regression analysis, a significant relationship was identified between the Nakata index before the bidirectional Glenn procedure and the absolute change in Nakata index (r = 0.83). A significant decrease in Nakata index occurred only in patients with a bidirectional Glenn shunt in place more than 15 months. Sixteen of the 30 patients subsequently underwent total cavo-pulmonary anastomosis with 7 requiring concurrent surgical pulmonary artery reconstruction. Changes in pulmonary artery size observed more than 15 months after the bidirectional Glenn procedure may have implications for subsequent Fontan repair in children with univentricular anatomy.