Clinical Implications of Major Aortopulmonary Collateral Arteries in Patients With Right Isomerism

Pre-Glenn aorto-pulmonary collaterals in single-ventricle patients

BACKGROUND

In single-ventricle patients undergoing staged-bidirectional Glenn, 36-59% have aorto-pulmonary collateral flow, but risk factors and clinical outcomes are unknown. We hypothesise that shunt type and catheter haemodynamics may predict pre-bidirectional Glenn aorto-pulmonary collateral burden, which may predict death/transplantation, pulmonary artery or aorto-pulmonary collateral intervention.

METHODS

Retrospective cohort study of patients undergoing a Norwood procedure for single-ventricle anatomy. Covariates included clinical and haemodynamic characteristics up to/including pre-bidirectional Glenn catheterisation and aorto-pulmonary collateral burden at pre-bidirectional Glenn catheterisation. Multivariable models used to evaluate relationships between risk factors and outcomes.

RESULTS

From January 2011 to March 2016, 104 patients underwent Norwood intervention. Male sex (odds ratio 3.36, 95% confidence interval 1.17-11.4), age at pre-bidirectional Glenn assessment (2.12, 1.33-3.39 per month), and pulmonary to systemic flow ratio (1.23, 1.08-1.41 per 0.1 unit) were associated with aorto-pulmonary collateral burden. Aorto-pulmonary collateral burden was not associated with death/transplantation (hazard ratio 1.19, 95% confidence interval 0.37-3.85), pulmonary artery (sub-hazard ratio 1.38, 0.32-2.61), or aorto-pulmonary collateral interventions (sub-hazard ratio 1.11, 0.21-5.76). Longer post-Norwood length of stay was associated with greater risk of death/transplantation (hazard ratio 1.22 per week, 95% confidence interval 1.08-1.38), but lower risk of aorto-pulmonary collateral intervention (sub-hazard ratio 0.86 per week, 95% confidence interval 0.75-0.98). Time to pre-bidirectional Glenn catheterisation was associated with lower risk of pulmonary artery (sub-hazard ratio 0.80 per month, 95% confidence interval 0.65-0.98) and aorto-pulmonary collateral intervention (sub-hazard ratio 0.79, 0.63-0.99). Probability of moderate/severe aorto-pulmonary collateral burden increased with left-to-right shunt (22.5% at <1.0, 57.6% at >1.4) and the age at pre-bidirectional Glenn catheterisation (10.6% at <2 months, 56.9% at >5 months).

CONCLUSIONS

Aorto-pulmonary collateral burden is common after Norwood procedure and increases as age at bidirectional Glenn increases. As expected, higher pulmonary to systemic flow ratio is a marker for greater aorto-pulmonary collateral burden pre-bi-directional Glenn; aorto-pulmonary collateral burden does not confer risk of death/transplantation or pulmonary artery intervention.

Unique foetal diagnosis of aorto-pulmonary collaterals in right atrial isomerism

Right atrial isomerism is associated with complex cardiac malformations, particularly single-ventricle lesions; right atrial isomerism is rarely associated with aorto-pulmonary collateral arteries. We report a foetal diagnosis of right atrial isomerism, with an unbalanced atrioventricular septal defect, pulmonary stenosis, total anomalous venous drainage, and significant aorto-pulmonary collaterals diagnosed at 22 weeks' gestation.

Severe bacterial infection in patients with heterotaxy syndrome

OBJECTIVE

To determine the incidence of sepsis in patients with heterotaxy syndrome.

STUDY DESIGN

From our institutional database, we identified patients with heterotaxy syndrome and other complex congenital heart disease (CHD) born between 2001 and 2011. Severe bacterial infection was defined as sepsis with positive culture result or infection with abscess formation.

RESULTS

We enrolled 95 patients with heterotaxy syndrome (88 with right atrial isomerism and 7 with left atrial isomerism) and 142 patients with complex CHD. With 1026 person-years follow-up, the 5-year survival was 52% and 65.7% in heterotaxy and complex CHD groups, respectively (P = .239). Community-acquired severe bacterial infection occurred only in heterotaxy syndrome (13 episodes in 10 patients, 3 of whom had spleen noted at imaging study) with 2- and 5 years cumulative severe bacterial infection rate of 9.6% and 14.5%, respectively. The overall mortality rate of those with community-acquired severe bacterial infection was 31%. Pneumococcus and Citrobacter freundii were the most common pathogens. Nosocomial severe bacterial infection occurred in 33.3% of all patients and 12.5% of all procedures. The rates (0.59 and 0.52/100 hospitalization days in heterotaxy and complex CHD group) and the pathogens of nosocomial severe bacterial infection were similar between heterotaxy and complex CHD groups.

CONCLUSIONS

Patients with heterotaxy syndrome are at high risk for community-acquired severe bacterial infection and also have high mortality rate whether the spleen is present or not. The risk of nosocomial severe bacterial infection seems similar to that of patients with other complex CHD.

Systemic-to-pulmonary collateral flow, as measured by cardiac magnetic resonance imaging, is associated with acute post-Fontan clinical outcomes

BACKGROUND

Systemic-pulmonary collateral (SPC) flow occurs commonly in single ventricle patients after superior cavo-pulmonary connection, with unclear clinical significance. We sought to evaluate the association between SPC flow and acute post-Fontan clinical outcomes using a novel method of quantifying SPC flow by cardiac magnetic resonance (CMR) imaging.

METHODS AND RESULTS

All patients who had SPC flow quantified by CMR imaging before Fontan were retrospectively reviewed to assess for acute clinical outcomes after Fontan completion. Forty-four subjects were included who had Fontan completion between May 2008 and September 2010. SPC flow prior to Fontan measured 1.5±0.9 L/min/m(2), accounting for 31±11% of total aortic flow and 44±15% of total pulmonary venous flow. There was a significant linear association between natural log-transformed duration of hospitalization and SPC flow as a proportion of total aortic (rho=0.31, P=0.04) and total pulmonary venous flow (rho=0.29, P=0.05). After adjustment for Fontan type and presence of a fenestration, absolute SPC flow was significantly associated with hospital duration ≥7 days (odds ratio [OR]=9.2, P=0.02) and chest tube duration ≥10 days (OR=22.7, P=0.009). Similar associations exist for SPC flow as a percentage of total aortic (OR=1.09, P=0.048 for hospitalization ≥7 days; OR=1.24, P=0.007 for chest tube duration ≥10 days) and total pulmonary venous flow (OR=1.07, P=0.048 for hospitalization ≥7 days; OR=1.18, P=0.006 for chest tube duration ≥10 days).

CONCLUSIONS

Increasing SPC flow before Fontan, as measured by CMR imaging, is associated with increased duration of hospitalization and chest tube following Fontan completion.

Quantification of collateral aortopulmonary flow in patients subsequent to construction of bidirectional cavopulmonary shunts

OBJECTIVES

We sought to provide a new method for quantifying collateral aortopulmonary flow in patients subsequent to construction of a bidirectional cavopulmonary shunt, and to clarify the clinical advantages of the new method.

METHODS

We performed lung perfusion scintigraphy and cardiac catheterization in 10 patients subsequent to construction of a bidirectional cavopulmonary shunt. First, the ratio of collateral to systemic flow was determined by whole-body images of lung perfusion scintigraphy, dividing the total lung count by the total body count minus the total lung count. Second, we integrated lung perfusion scintigraphy and cardiac catheterization data using a formula derived from the Fick principle, taking the ratio of pulmonary to systemic flow to be 1 plus the ratio calculated above and multiplied by the systemic saturation minus the inferior caval venous saturation divided by the pulmonary venous saturation minus the inferior caval venous saturation. Finally, the amount of collateral flow was obtained from the ratio of pulmonary to systemic flow. We evaluated the impact of collateral flow on the calculation of pulmonary vascular resistance.

RESULTS

The median age at bidirectional cavopulmonary shunt was 1.41 years, and the median age at catheterization was 2.33 years. The mean amount of collateral flow was 1.75 +/- 0.46 litres/min/m(2). The pulmonary vascular resistance calculated without considering the collateral flow was overestimated by an average of 57 +/- 23%, compared to the resistance calculated with our new method.

CONCLUSIONS

The use of scintigraphy combined with catheterization allows accurate determination of aortopulmonary collateral flow, and avoids overestimation of pulmonary vascular resistance in these candidates for the Fontan circulation.