Improved management of systemic venous anomalies in a single ventricle: New rationale

Pulmonary venous obstruction after extracardiac total cavopulmonary connection in right atrial isomerism

BACKGROUND

Patients with functional single ventricle and right atrial isomerism (RAI) often have multiform cardiac pulmonary venous (PV) connection, which could be a risk factor for pulmonary venous obstruction (PVO) after extracardiac total cavopulmonary connection (EC-TCPC) owing to compression of the conduit.

OBJECTIVE

To investigate the anatomical risk factors for PVO after EC-TCPC in RAI.

METHODS

Twenty-nine patients with RAI without extracardiac total anomalous pulmonary venous connection were enrolled. No patients had PVO before EC-TCPC. A total of 14 and 15 patients had PV orifices ipsilateral and contralateral to the extracardiac conduit, respectively. The former 14 patients were assigned to two groups based on development of PVO after EC-TCPC (groups O and N). The pre- and post-operative cardiac morphologies and their relationship with the conduit were compared.

RESULTS

After the EC-TCPC, the pressure gradients between the atrium and the PV were 5.0 ± 2.5 and 0.44 ± 0.2 mmHg in groups O and N, respectively (p < 0.01); however, the pressure gradients in the left and right PVs were not significantly different, suggesting stenosis of the common PV orifice. The ratio of the horizontal distance from the vertebrae to the PV orifice and to the lateral edge of the atrium was significantly higher (0.38 ± 0.2 vs. 0.17 ± 0.1; p = 0.04) and the orifice was smaller (8.9 ± 2.0 vs. 15 ± 4.7 mm; p < 0.01) in group O than in group N.

CONCLUSION

In cases with ipsilateral locations of the conduit and PV orifice, small size and more lateral location of the PV orifice may be preoperative risk factors for development of PVO.

Flow Dynamics of Bilateral Superior Cavopulomonary Shunts Influence Outcomes After Fontan Completion

Bilateral superior vena cava (SVC), which occurs following bilateral bidirectional cavopulmonary shunt (BCPS), is an anomaly marked by unique hemodynamics. This study aimed to determine its effects on outcomes after Fontan completion. Among 405 patients who underwent BCPS and total cavopulmonary connection (TCPC) between 1997 and 2017, 40 required a bilateral-BCPS. The dominant SVC prior to TCPC was identified according to the direction of blood flow in the central pulmonary artery, and its relationship to the inferior vena cava (IVC) was classified as a concordant or discordant relationship. Preoperative factors were analyzed to identify the risk factors for specific adverse outcomes. The length of intensive care unit (ICU) stay after TCPC was longer in the 40 patients who underwent bilateral-BCPS than in those who underwent unilateral BCPS (p = 0.024), and the survival rate was lower in the former group than in the latter group (p = 0.004). In the patients who underwent bilateral-BCPS, the dominant SVC was concordant with the IVC in 30 patients and discordant in 10 patients. With regard to whether certain morphological, hemodynamic, and flow dynamics-related variables were risk factors for adverse outcomes following TCPC, a discordant relationship between dominant SVC and IVC was identified as an independent risk factor for both a longer ICU stay (p = 0.037, HR 2.370) and worse survival (p = 0.019, HR 13.880). Therefore, in patients with a bilateral SVC who have previously undergone bilateral-BCPS, a discordant relationship between dominant SVC and IVC might contribute to worse outcomes following TCPC.

Numerical Investigation of the Effect of Additional Pulmonary Blood Flow on Patient-Specific Bilateral Bidirectional Glenn Hemodynamics

The effect of additional pulmonary blood flow (APBF) on the hemodynamics of bilateral bidirectional Glenn (BBDG) connection was marginally discussed in previous studies. This study assessed this effect using patient-specific numerical simulation. A 15-year-old female patient who underwent BBDG was enrolled in this study. Patient-specific anatomy, flow waveforms, and pressure tracings were obtained using computed tomography, Doppler ultrasound technology, and catheterization, respectively. Computational fluid dynamic simulations were performed to assess flow field and derived hemodynamic metrics of the BBDG connection with various APBF. APBF showed noticeable effects on the hemodynamics of the BBDG connection. It suppressed flow mixing in the connection, which resulted in a more antegrade flow structure. Also, as the APBF rate increases, both power loss and reflux in superior venae cavae (SVCs) monotonically increases while the flow ratio of the right to the left pulmonary artery (RPA/LPA) monotonically decreases. However, a non-monotonic relationship was observed between the APBF rate and indexed power loss. A high APBF rate may result in a good flow ratio of RPA/LPA but with the side effect of bad power loss and remarkable reflux in SVCs, and vice versa. A moderate APBF rate could be favourable because it leads to an optimal indexed power loss and achieves the acceptable flow ratio of RPA/LPA without causing severe power loss and reflux in SVCs. These findings suggest that patient-specific numerical simulation should be used to assist clinicians in determining an appropriate APBF rate based on desired outcomes on a patient-specific basis.

Systemic venous anomalies in the Middle East

INTRODUCTION

Systemic venous anomalies are quite rare and can be associated with congenital heart disease requiring surgery.

MATERIALS AND METHODS

All consecutive patients (pts) undergoing surgery for congenital heart defects were retrospectively analyzed for presence of systemic venous anomalies: (a) Persistent left superior vena cava (PLSVC)(b) Inferior vena cava (IVC) interruption(c) Retro-aortic innominate vein Results: From 9/2010 to 5/2012 155 pts, median age 7 months, mean age 1.3 years (3 days-50 years), median weight 4 kg, mean weight 7.2 kg (0.6-110 kg) underwent congenital heart surgery. Twenty-nine systemic venous anomalies were identified in 28/155 patients (=18.1%). PLSVC was present in 21 pts (=13.5%), median age 4 months, mean age 2.7 years (3 days-22 years), median weight 6 kg, mean weight 10.1 kg (2.4-43.0 kg). IVC interruption was identified in 5 pts (=3.2%), median age 2 months, mean age 5.4 years (30 days-26 years), median weight 3.7 kg, median weight 17 kg (2.3-68.0 kg). Retro-aortic innominate vein was diagnosed in 3 pts (=1.9%), median age 5 years, mean age 3.7 years (10 months-5 years), median weight 12 kg, mean weight 10.1 kg (4.5-14 kg). Complete pre-operative diagnosis was obtained in 14/28 (=50%) pts with echocardiography and in other 8/28 (=28.6%) only after computed tomography (CT) scan, for a total of 22/28 (=78.6%) correct pre-operative diagnosis. In 6/28 (=21.4%) patients the diagnosis was intra-operative. Total incidence of systemic venous anomalies was 18.1% (vs. 4% in the literature, P = 0.0009), with presence of PLSVC = 13.5% (vs. 0.3-4.0%, respectively P = 0.0004 and P = 0.0012), IVC interruption = 3.2% (vs. 0.1-1.3%, N.S.), and retro-aortic innominate vein = 1.9% (vs. 0.2-1%, N.S.).

CONCLUSIONS

Our study showed an incidence of systemic venous anomalies in Middle Eastern pts with congenital heart defects higher than previously reported. In 78.6% of pts the diagnosis was correctly made before surgery (echocardiography or CT scan), with 21.4% of complete diagnosis made at surgery. A careful pre-operative screening should be performed in all pts with congenital heart defects from this region to better identify all systemic venous anomalies for a more accurate surgical planning.