Additional pulmonary blood flow with the bidirectional Glenn anastomosis: does it make a difference?

Impact of Antegrade Pulmonary Blood Flow as Patients Progress Through Single-Ventricle Palliations

BACKGROUND

The impact of antegrade pulmonary blood flow (APBF) during single-ventricle (SV) palliation continues to be debated. We sought to assess its impact on the hemodynamic profile and the short- and long-term outcomes of patients progressing through stages of SV palliation.

METHODS

A retrospective single-center study was conducted of SV patients who underwent surgery between January 2010 and December 2020. Patients with APBF were matched to those with no APBF by a propensity score based on body surface area, sex, and type of systemic ventricle. Analysis was performed using appropriate statistics with a significance level of P = .05.

RESULTS

Sixty-three patients with APBF were matched with 95 patients with no APBF. At the pre-stage 2 catheterization, APBF patients had a larger left pulmonary artery diameter (z score, 0.1 vs -0.8; P < .042). Patients with APBF had shorter cardiopulmonary bypass time (57.0 vs 79.0 minutes), shorter duration of mechanical ventilation (14.1 vs 17.4 hours), and shorter hospital length of stay (5.0 vs 7.0 days) at stage 2 palliation (P < .05). In the multivariable Cox regression analysis, patients with hypoplastic pulmonary arteries (z scores < -2; adjusted hazard ratio, 9.17) and patients with chromosomal abnormalities/genetic syndrome (adjusted hazard ratio, 4.03) were at increased risk for poor outcomes (P < .05). During the follow-up period, there was no significant difference in risk of the composite poor outcome and long-term survival between groups.

CONCLUSIONS

SV patients with APBF had shorter cardiopulmonary bypass time, duration of mechanical ventilation, and hospital length of stay after stage 2 palliation. Patients with hypoplastic pulmonary arteries or chromosomal abnormalities/genetic syndromes had increased risk for poor outcomes. Maintaining APBF has better short-term outcomes, but there are no long-term hemodynamic or survival benefits.

Does leaving native antegrade pulmonary blood flow at the time of the superior cavopulmonary connection impact long-term outcomes after the Fontan?

Objectives

Antegrade pulmonary blood flow (APBF) may be left or eliminated at the time of the superior cavopulmonary connection (SCPC). Our aim was to assess the impact of leaving native APBF at the SCPC on long-term Fontan outcomes.

Methods

In the Australia and New Zealand Fontan Registry (1985-2021), 587 patients had pre-existing native APBF at the SCPC. At the SCPC, 302 patients had APBF eliminated (APBF-) and 285 patients had APBF maintained (APBF+). The incidence of Fontan failure (composite end point of Fontan takedown, transplant, plastic bronchitis, protein losing enteropathy and death) and atrioventricular (AV) valve repair/replacement post SCPC was compared between the 2 groups.

Results

Sex, predominant-ventricle morphology, isomerism, primary diagnosis, and age/type of Fontan were similar between groups. APBF- versus APBF+ had a higher incidence of arch obstruction/coarctation (17% vs 7%) and previous pulmonary artery band (54% vs 45%) and a lower rate of Fontan fenestration (27% vs 41%). The risk of Fontan failure was similar between the 2 groups (hazard ratio [HR], 1.01; 95% confidence interval [CI], 0.58-1.78; P = .96). The risk of AV-valve repair/replacement was greater in APBF+ versus APBF- (HR, 2.32; CI, 1.13-4.75; P = .022). The risk of AV-valve repair/replacement remained after adjustment for arch obstruction/coarctation, previous pulmonary artery band and Fontan fenestration (HR, 2.27; CI, 1.07-4.81; P = .033).

Conclusions

Maintaining APBF at the time of the SCPC does not impact the risk of Fontan failure but may increase the incidence of AV-valve repair and/or replacement post-SCPC.

Influence of Antegrade Pulmonary Blood Flow on Outcomes of Superior Cavopulmonary Connection

BACKGROUND

We sought to characterize short- and long-term outcomes after superior cavopulmonary connection (SCPC) in children eligible for inclusion of antegrade pulmonary blood flow (APBF) in the SCPC circuit, exploring whether maintaining APBF was associated with outcomes.

METHODS

This was a retrospective cohort study of patients with single-ventricle heart disease and APBF who underwent SCPC at our center between January 1, 2000, and September 30, 2017. Patients were divided into 2 groups: APBF eliminated (APBF-), and APBF maintained (APBF+) at the time of SCPC.

RESULTS

Of 149 patients, 108 (72.5%) were in APBF- and 41 (27.5%) were in APBF+. Of those in APBF+, 5 (12.2%) subsequently had APBF eliminated after SCPC. Patients in APBF+ had a higher prevalence of chest tube duration >10 days and underwent more interventions during the post-SCPC hospitalization (1.9% vs 12%; P = .008 for both) but had shorter surgical support times at SCPC (P < .0001). There were no differences in post-SCPC intensive care unit or hospital length of stay. During the study period, 82 patients (76%) in APBF- and 22 patients (54%) in APBF+ underwent Fontan completion. Patients in APBF+ had a greater weight gain from SCPC to Fontan (6.7 [1.8-22] kg vs 8.15 [4.4-20.6] kg; P = .012) and a shorter hospital length of stay after Fontan (9 [4-107] days vs 7.5 [4-14] days; P = .044).

CONCLUSIONS

Short-term morbidity associated with maintaining APBF at the time of SCPC is modest, but longer term outcomes suggest potential benefits in those in whom APBF can be successfully maintained.

Early outcomes after the on pump bidirectional Glenn procedure: A single center experience

OBJECTIVE

Bidirectional Glenn procedure is a staged palliative procedure for patients with the univentricular hearts or complex congenital heart disease. We in our study, attempted to evaluate the preoperative characteristics, operative data and the early postoperative outcomes in the patients who underwent Bidirectional Glenn procedure at our center.

METHODS

In our single center retrospective experience, 115 patients underwent Bidirectional Glenn procedure from January 2015 to December 2019.

RESULTS

The mean age of the patients was 6.55 ± 6.5 years (range from 9 months to 48 years) and a median of 5 years. The most common anatomic diagnosis was double outlet right ventricle (n = 49, 42.6%). The primary diagnosis and the additional cardiac anamolies were not associated with the adverse outcomes. The increased cardiopulmonary bypass and operative time affect the postoperative outcomes. The median oxygen saturation in the patients postoperatively was 82%. The median postoperative stay was 8 days. The early postoperative complications were seen in 29 patients (25.2%). There were 12 early deaths (10.4%) in our study. The late age of presentation and poor preoperative nutrition, increased the risk of the postoperative morbidity and mortality.

CONCLUSION

Bidirectional Glenn procedure is an effective procedure to improve efficacy of the gas exchange and reduce volume overload on the single ventricle at early as well as late stages. However, the late age of presentation increases the risk of the postoperative outcomes.

Does Maintenance of Pulmonary Blood Flow Pulsatility at the Time of the Fontan Operation Improve Hemodynamic Outcome in Functionally Univentricular Hearts?

It is unclear whether residual anterograde pulmonary blood flow (APBF) at the time of Fontan is beneficial. Pulsatile pulmonary flow may be important in maintaining a compliant and healthy vascular circuit. We, therefore, wished to ascertain whether there was hemodynamic evidence that residual pulsatile flow at time of Fontan promotes clinical benefit. 106 consecutive children with Fontan completion (1999-2018) were included. Pulmonary artery pulsatility index (PI, (systolic pressure-diastolic pressure)/mean pressure)) was calculated from preoperative cardiac catheterization. Spectral analysis charted PI as a continuum against clinical outcome. The population was subsequently divided into three pulsatility subgroups to facilitate further comparison. Median PI prior to Fontan was 0.236 (range 0-1). 39 had APBF, in whom PI was significantly greater (median: 0.364 vs. 0.177, Mann-Whitney p < 0.0001). There were four early hospital deaths (3.77%), and PI in these patients ranged from 0.214 to 0.423. There was no correlation between PI and standard cardiac surgical outcomes or systemic oxygen saturation at discharge. Median follow-up time was 4.33 years (range 0.0273-19.6), with no late deaths. Increased pulsatility was associated with higher oxygen saturations in the long term, but there was no difference in reported exercise tolerance (Ross), ventricular function, or atrioventricular valve regurgitation at follow-up. PI in those with Fontan-associated complications or the requiring pulmonary vasodilators aligned with the overall population median. Maintenance of pulmonary flow pulsatility did not alter short-term outcomes or long-term prognosis following Fontan although it tended to increase postoperative oxygen saturations, which may be beneficial in later life.

The impact of additional antegrade pulmonary blood flow at bidirectional Glenn shunt on long-term outcomes

OBJECTIVES

We investigated the impact of additional antegrade pulmonary blood flow on the long-term outcomes after bidirectional Glenn shunt.

METHODS

From 2001 to 2015, 279 patients underwent bidirectional Glenn shunt as an interim palliation for a functionally single ventricle. After excluding patients with a previous Kawashima or Norwood operation, 202 patients with preexisting antegrade pulmonary blood flow before bidirectional Glenn shunt were included in this study. Antegrade pulmonary blood flow was eliminated in 110 patients (no antegrade pulmonary blood flow group) and maintained in 92 patients (antegrade pulmonary blood flow group). The impact of antegrade pulmonary blood flow at bidirectional Glenn shunt on long-term outcome was analyzed using inverse probability of treatment weighting.

RESULTS

Median age and body weight at bidirectional Glenn shunt were 8 months and 7.8 kg, respectively. Prolonged chest tube drainage or readmission for effusion after bidirectional Glenn shunt was more frequent in the antegrade pulmonary blood flow group (odds ratio, 3.067; 95% confidence interval, 1.036-9.073; P = .043). In the no antegrade pulmonary blood flow group, B-type natriuretic peptide level was decreased further until the Fontan operation (P = .012). In the no antegrade pulmonary blood flow group, oxygen saturation was lower just after bidirectional Glenn shunt, although it was increased further until Fontan operation (P < .001), despite still lower oxygen saturation before Fontan operation compared with antegrade pulmonary blood flow group (P < .001). The McGoon ratio was decreased in both groups without intergroup difference, although the McGoon ratio before Fontan operation was higher in the antegrade pulmonary blood flow group (2.3 ± 0.4 vs 2.1 ± 0.4, P = .008). Overall transplant-free survival was worse in the antegrade pulmonary blood flow group (hazard ratio, 2.37; confidence interval, 1.089-5.152; P = .030).

CONCLUSIONS

Maintaining antegrade pulmonary blood flow at bidirectional Glenn shunt was beneficial for higher oxygen saturation and larger pulmonary artery size before Fontan operation. However, it was unfavorable for overall transplant-free survival with a sustained higher risk of death or transplant until the elimination of antegrade pulmonary blood flow.

Post-Fontan pulmonary artery growth in patients with a bidirectional cavopulmonary shunt with additional antegrade pulsatile blood flow

Background

Patients with antegrade pulmonary blood flow after a bidirectional cavopulmonary shunt (Glenn) may have better pulmonary artery growth. This study evaluated pulmonary artery growth in patients with and without prior additional pulsatile antegrade flow in a Glenn shunt at midterm follow-up after a Fontan procedure.

Methods

We reviewed 212 patients who had single-ventricle palliation in a 10-year period;103 (33 in pulsatile group 1 and 70 in nonpulsatile group 2) were selected for analysis. Data on demographics, procedures, perioperative course, and midterm follow-up after the Fontan procedure were compared. Echocardiography data were collected. Pulmonary artery sizes measured at cardiac catheterization and follow-up echocardiograms were used to calculate the Nakata index.

Results

Perioperative details were comparable in both groups, mean pulmonary artery pressure and systemic oxygen saturations were higher in group 1 compared to group 2. Venovenous collaterals were increased in group 1. There was a significant difference in the pre-Fontan and follow-up Nakata index between groups. There was a significant increase in the Nakata index in group 1 between the pre-Glenn and pre-Fontan assessments as well as the Nakata index between the pre-Fontan and midterm follow-up. There was no significant change in the Nakata index in group 2 between assessments.

Conclusions

A pulsatile Glenn shunt is associated with better pulmonary artery growth which continues long after the additional pulsatile flow is eliminated. It is possible that the effects of anterograde pulmonary blood flow on pulmonary artery growth in early life continue long after the Fontan completion.

Transcatheter occlusion of antegrade pulmonary blood flow in children with univentricular heart

Background

This study aims to evaluate the results of transcatheter occlusion of antegrade pulmonary blood flow in children with univentricular heart.

Methods

Medical data of a total of seven patients (4 females, 3 males; median age 11.7 years; range, 1 to 24 years) who underwent transcatheter occlusion of the antegrade pulmonary blood flow following Glenn shunt or Fontan operation between September 2014 and January 2017 were retrospectively analyzed. Data including demographic and clinical characteristics of the patients, type of surgery, echocardiographic and cardiac catheterization findings were recorded.

Results

Four patients had a previous pulmonary artery banding operation, while three had pulmonary stenosis. Two patients had facial and upper extremity edema after Glenn operation, one had prolonged pleural effusion, one had prolonged pleural effusion after Fontan operation, and one developed dyspnea and effort intolerance several years after Fontan operation. In two patients, antegrade pulmonary blood flow was occluded to decrease systemic ventricular load before surgery. The Amplatzer Septal Occluder was used in five patients and the Amplatzer Vascular Plug-2 was used in two patients. Two patients developed transient, complete atrioventricular block during the procedure and the procedure was terminated early in one of these patients. Transient hemolysis was observed in one patient following the operation.

Conclusion

Transcatheter occlusion of antegrade pulmonary blood flow is an effective alternative to surgery in patients with hemodynamic compromise after Glenn shunt or Fontan operation.

The effects of ventilation on left-to-right shunt and regional cerebral oxygen saturation: a self-controlled trial

BACKGROUND

Increase of pulmonary vascular resistance (PVR) is an efficient method of modulating pulmonary and systemic blood flows (Qp/Qs) for patients with left-to-right (L-R) shunt, and is also closely associated with insufficient oxygen exchange for pulmonary hypoperfusion. So that it might be a preferred regime of maintaining arterial partial pressure of carbon dioxide tension (PaCO₂) within an optimal boundary via ventilation management in congenital heart disease (CHD) patients for the inconvenient measure of the PVR and Qp/Qs. However, the appropriate range of PaCO₂ and patient-specific mechanical ventilation settings remain controversial for CHD children with L-R shunt.

METHODS

Thirty-one pediatric patients with L-R shunt, 1-6 yr of age, were included in this observation study. Patients were ventilated with tidal volume (V_T) of 10, 8 and 6 ml/kg in sequence, and 15 min stabilization period for individual V_T. The velocity time integral (VTI) of L-R shunt, pulmonary artery (PA) and descending aorta (DA) were measured with transesophageal echocardiography (TEE) after an initial 15 min stabilization period for each V_T, with arterial blood gas analysis. Near-infrared spectroscopy sensor were positioned on the surface of the bilateral temporal artery to monitor the change in regional cerebral oxygen saturation (rScO₂).

RESULTS

PaCO₂ was 31.51 ± 0.65 mmHg at V_T 10 ml/kg vs. 37.15 ± 0.75 mmHg at V_T 8 ml/kg (P < 0.03), with 44.24 ± 0.99 mmHg at V_T 6 ml/kg significantly higher than 37.15 ± 0.75 mmHg at V_T 8 ml/kg. However, PaO₂ at a V_T of 6 ml/kg was lower than that at a V_T of 10 ml/kg (P = 0.05). Meanwhile, 72% (22/31) patients had PaCO₂ in the range of 40-50 mmHg at V_T 6 ml/kg. VTI of L-R shunt and PA at V_T 6 ml/kg were lower than that at V_T of 8 and 10 ml/kg (P < 0.05). rScO₂ at a V_T of 6 ml/kg was higher than that at a V_T of 8 and 10 ml/kg (P < 0.05), with a significantly correlation between rScO₂ and PaCO₂ (r = 0.53). VTI of PA in patients with defect diameter > 10 mm was higher that that in patients with defect diameter ≤ 10 mm.

CONCLUSIONS

Maintaining PaCO₂ in the boundary of 40-50 mmHg with V_T 6 ml/kg might be a feasible ventilation regime to achieve better oxygenation for patients with L-R shunt. Continue raising PaCO₂ should be careful.

TRAIL REGISTRATION

Clinical Trial Registry of China (http://www.chictr.org.cn) identifier: ChiCTR-OOC-17011338 , prospectively registered on May 9, 2017.

Pulsatile Glenn as long-term palliation for single ventricle physiology patients

OBJECTIVE

There are limited studies analyzing pulsatile Glenn as a long-term palliation strategy for single ventricle patients. This study sought to determine their outcomes at a single institution.

DESIGN

A retrospective review was performed.

SETTING

Study performed at a single pediatric hospital.

PATIENTS

All single ventricle patients who underwent pulsatile Glenn from 1995 to 2016 were included.

OUTCOME MEASURES

Pulsatile Glenn failure was defined as takedown, transplant, or death. Further palliation was defined as Fontan, 1.5, or biventricular repair. Risk factors were assessed by Cox multivariable competing risk analyses.

RESULTS

Seventy-eight patients underwent pulsatile Glenn at age 9 months (interquartile range, 5-14). In total, 28% had heterotaxy, 18% had a genetic syndrome, and 24% had an abnormal inferior vena cava. There were 3 (4%) perioperative mortalities. Further palliation was performed in 41 (53%) patients with a median time-to-palliation of 4 years (interquartile range, 3-5). Pulsatile Glenn failure occurred in 10 (13%) patients with 8 total mortalities. Five- and 10-year transplant-free survival were 91% and 84%, respectively. At a median follow-up of 6 years (interquartile range, 2-8), 27 patients (35%) remained with PG (age 7 years [interquartile range, 3-11], oxygen saturation 83% ± 4%). Preoperative moderate-severe atrioventricular valve regurgitation (AVVR) (hazard ratio 7.77; 95% confidence interval 1.80-33.43; P =.005) and higher pulmonary vascular resistance (hazard ratio 2.59; 95% confidence interval 1.08-6.15; P =.031) were predictors of pulsatile Glenn failure after adjusting for covariates. Reaching further palliation was less likely in patients with preoperative moderate-severe AVVR (hazard ratio 0.22, 95% confidence interval 0.08-0.59; P =.002).

CONCLUSION

Pulsatile Glenn can be an effective tool to be used in challenging circumstances, these patients can have a favorable long-term prognosis without reducing their suitability for further palliation.

The effect of antegrade pulmonary blood flow following a late bidirectional Glenn procedure

OBJECTIVES

The effect of antegrade pulmonary blood flow (APBF) has never been studied in the bidirectional Glenn (BDG) procedure performed late.

METHODS

Records of 112 consecutive patients who had a BDG procedure during a 10-year period were reviewed retrospectively. The patients were divided into 2 groups based on whether APBF occurred following the BDG procedure (APBF group, n = 81) or not (non-APBF group, n = 31). The median age at the BDG procedure was 6.16 ± 3.93 years in the APBF group and 6.12 ± 4.40 years in the non-APBF group.

RESULTS

Demographics and pre- and intraoperative variables were comparable for both groups. Follow-up data were obtained for patients at the BDG stage and for those who had undergone the Fontan completion. Both oxygen saturation levels (81.72 ± 1.976% vs 78.32 ± 2.344%, P < 0.01) and pulmonary pressure (13.59 ± 1.376 mmHg vs 12.90 ± 0.978 mmHg, P = 0.012) were higher in the APBF group immediately after the BDG procedure. Both the duration of chest tube drainage and the total length of stay were longer in the APBF group. The pre-Glenn measurements showed a mean McGoon ratio of 1.68 ± 0.114 in the APBF group and 1.67 ± 0.098 in the non-APBF group (P = 0.474). The McGoon ratios measured before the Fontan procedure were also comparable (1.669 ± 0.726 vs 1.685 ± 0.669, P = 0.576). At the pre-Fontan measurement, there was no significant difference in mean pulmonary artery pressures between the groups (13.72 ± 1.368 vs 13.50 ± 1.265, P = 0.653). Fifty-nine patients underwent the Fontan completion (43 from the APBF group and 16 from the non-APBF group) procedure with a median of 1.2 (APBF group) and 1.4 (non-APBF group) years after the BDG procedure. No significant differences between groups were observed in arterial oxygen saturation levels, incidence of systemic atrioventricular valve regurgitation or ventricular dysfunction in survivors at the last follow-up visit.

CONCLUSIONS

The BDG procedure can be safely performed at a relatively older age (∼6 years). APBF increases oxygen saturation but also prolongs pleural effusion and hospital stay. Medium-term outcomes and the Fontan completion rate in the APBF and the non-APBF groups are comparable. Further large studies and long-term follow-up are needed to clarify the effect of APBF in patients who have the late BDG.

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.

Clinical Application of Bidirectional Glenn Shunt with Off-Pump Technique

A study was conducted to evaluate the outcomes of the bidirectional Glenn shunt technique performed off-pump. Between April 1999 and April 2001, 36 patients underwent bidirectional Glenn shunt, unilateral in 28 patients and bilateral in 8 patients, without using cardiopulmonary bypass. The patients consisted of 25 males and 11 females with a mean age of 5.7 ± 5.4 years and a mean body surface area of 0.72 ± 0.34 m2. Preoperative percutaneous oxygen saturation was 75% ± 7%, and pulmonary arterial pressure was 14.3 ± 3.6 mmHg. There was no operative mortality. Chylothorax occurred in 1 patient in the early postoperative period. All the other patients were discharged without complications. Mean arterial oxygen saturation at discharge was 92.7% ± 4.0%. This shunt technique is easy to perform and is helpful in the early management of patients with a functionally univentricular heart. However, much remains to be learned about this unusual physiological system.

Uncontrolled Antegrade Pulmonary Blood Flow and Delayed Fontan Completion After the Bidirectional Glenn Procedure: Real-World Outcomes in China

BACKGROUND

Given the low rate of Fontan completion, an aggressive policy for maintaining antegrade pulmonary blood flow (AnPBF) during the bidirectional Glenn procedure (BDG) was developed for the functional single ventricle.

METHODS

From 2008 to 2013, 294 patients who underwent the BDG were divided into two groups: group 1 (uncontrolled AnPBF, n = 270) and group 2 (controlled AnPBF, n = 24). Pulmonary artery banding was performed because of the high central venous pressure in group 2. In group 1, the patients who underwent BDG from 2008 to 2012 were further divided into group DF (delayed Fontan completion, n = 109) and group FC (Fontan completion, n = 42).

RESULTS

The Fontan completion rate was 16.3%, and the average interval time was 2.2 ± 1.1 years. The delay of Fontan completion did not reduce body weight gain or the survival rate. Furthermore, oxygen saturation was slightly reduced in group DF. Although no impairments of heart function were observed, the uncontrolled AnPBF in group DF resulted in an increase in ventricular end-diastolic diameter and aggravation of atrioventricular valve regurgitation over 24 months after BDG. Logistic regression analysis revealed that systemic right ventricular morphology was a risk factor for the aggravation of valve regurgitation.

CONCLUSIONS

The low Fontan achievement rate is a critical issue in China. Although the patients with delayed Fontan completion exhibited an acceptable survival rate and acceptable body weight gain, uncontrolled AnPBF was associated with ventricular enlargement and aggravation of valve regurgitation. Strategies for improving the Fontan completion rate in China should be explored and could benefit outcomes.

In Vitro Assessment of the Assisted Bidirectional Glenn Procedure for Stage One Single Ventricle Repair

This in vitro study compares the hemodynamic performance of the Norwood and the Glenn circulations to assess the performance of a novel assisted bidirectional Glenn (ABG) procedure for stage one single ventricle surgery. In the ABG, the flow in a bidirectional Glenn procedure is assisted by injection of a high-energy flow stream from the systemic circulation using an aorta-caval shunt with nozzle. The aim is to explore experimentally the potential of the ABG as a surgical alternative to current surgical practice. The experiments are directly compared against previously published numerical simulations. A multiscale mock circulatory system was used to measure the hemodynamic performance of the three circulations. For each circulation, the system was tested using both low and high values of pulmonary vascular resistance. Resulting parameters measured were: pressure and flow rate at left/right pulmonary artery and superior vena cava (SVC). Systemic oxygen delivery (OD) was calculated. A parametric study of the ratio of ABG nozzle to shunt diameter was done. We report time-based comparisons with numerical simulations for the three surgical variants tested. The ABG circulation demonstrated an increase of 30-38% in pulmonary flow with a 2-3.7 mmHg increase in SVC pressure compared to the Glenn and a 4-14% higher systemic OD than either the Norwood or the Glenn. The nozzle/shunt diameter ratio affected the local hemodynamics. These experimental results agreed with those of the numerical model: mean flow values were not significantly different (p > 0.05) while mean pressures were comparable within 1.2 mmHg. The results verify the approaches providing two tools to study this complicated circulation. Using a realistic experimental model we demonstrate the performance of a novel surgical procedure with potential to improve patient hemodynamics in early palliation of the univentricular circulation.

Decision-Making for Surgery in the Management of Patients with Univentricular Heart

A series of technical refinements over the past 30 years, in combination with advances in perioperative management, have resulted in dramatic improvements in the survival of patients with univentricular heart. While the goal of single-ventricle palliation remains unchanged - normalization of the pressure and volume loads on the systemic ventricle, the strategies to achieve that goal have become more diverse. Optimal palliation relies on a thorough understanding of the changing physiology over the first years of life and the risks and consequences of each palliative strategy. This review describes how to optimize surgical decision-making in univentricular patients based on a current understanding of anatomy, physiology, and surgical palliation.

The assisted bidirectional Glenn: a novel surgical approach for first-stage single-ventricle heart palliation

BACKGROUND

Outcomes after a modified Blalock-Taussig shunt (mBTS) in neonates with single-ventricle physiology remain unsatisfactory. However, initial palliation with a superior cavopulmonary connection, such as a bidirectional Glenn (BDG), is discouraged, owing to potential for inadequate pulmonary blood flow (PBF). We tested the feasibility of a novel surgical approach, adopting the engineering concept of an ejector pump, whereby the flow in the BDG is "assisted" by injection of a high-energy flow stream from the systemic circulation.

METHODS

Realistic 3-dimensional models of the neonatal mBTS and BDG circulations were created. The "assisted" bidirectional Glenn (ABG) consisted of a shunt between the right innominate artery and the superior vena cava (SVC), with a 1.5-mm clip near the SVC anastomosis to create a Venturi effect. The 3 models were coupled to a validated hydraulic circulation model, and 2 pulmonary vascular resistance (PVR) values (7 and 2.3 Wood units) were simulated.

RESULTS

The ABG provided the highest systemic oxygen saturation and oxygen delivery at both PVR levels. In addition to achieving higher PBF than the BDG, the ABG produced a lower single-ventricular workload than mBTS. SVC pressure was highest in the ABG model (ABG: 15; Glenn: 11; mBTS: 3 mm Hg; PVR = 7 Wood units), but at low PVR, the SVC pressure was significantly lower (ABG: 8; Glenn: 6; mBTS: <3 mm Hg).

CONCLUSIONS

Adopting the principle of an ejector pump, with additional flow directed into the SVC in a BDG, the ABG appears to increase PBF with a modest increase in SVC and pulmonary arterial pressure. Although multiscale modeling results demonstrate the conceptual feasibility of the ABG circulation, further technical refinement and investigations are necessary, especially in an appropriate animal model.

Late bidirectional glenn anastomosis in a 54-year-old patient with unoperated functionally univentricular heart

We report the case of a 54-year-old patient with complex univentricular physiology who presented with worsening exercise intolerance, chronic cyanosis, and uncontrolled heart failure. Investigations included echocardiography, cardiac magnetic resonance imaging, and cardiac catheterization. After discussion in a multidisciplinary meeting, the patient underwent successful surgery that included a bidirectional Glenn anastomosis and repair of the atrioventricular (AV) junction. She recovered well and on follow-up had substantially less cyanosis and heart failure. We demonstrated that common AV valve repair and Glenn shunt can be used together successfully in appropriately selected older patients as palliation for complex congenital heart disease with functionally univentricular physiology.

Results of additional pulsatile pulmonary blood flow with bidirectional glenn cavopulmonary anastomosis: positive effect on main pulmonary artery growth and less need for fontan conversion

BACKGROUND

Additional antegrade pulsatile pulmonary blood flow obtained by leaving the main pulmonary artery patent during bidirectional cavopulmonary shunt has been shown to give additional benefits to the bidirectional Glenn cavopulmonary anastomosis. We retrospectively evaluated our 20-patient pulsatile Glenn series in order to find out whether these salutary effects were valid or not.

METHODS

Between June 2007 and November 2011, 20 patients (11 girls and 9 boys) with single-ventricle physiology underwent bidirectional cavopulmonary anastomosis. The additional source of blood flow was through the unligated main pulmonary artery in all patients. A retrospective review of our surgical experience was performed focusing on the role of additional pulmonary flow. Medical records and perioperational and postoperative follow-up data including clinical outcomes were retrospectively retrieved and analyzed.

RESULTS

Two patients died in the early postoperative period. One patient died in the follow-up period. Mean follow-up time was 23.9 ± 15.7 months. No superior vena cava syndrome and no increase in pulmonary vascular resistance were observed. Improvement of partial oxygen pressure after pulsatile Glenn has been shown in all patients (P = .00). At a mean interval of 22.9 months, main pulmonary artery size continued to increase after pulsatile Glenn cavopulmonary anastomosis (P = .028). Only 1 patient was converted to Fontan type circulation after pulsatile Glenn cavopulmonary anastomosis.

CONCLUSIONS

The pulsatile cavopulmonary shunt is a useful procedure in the early and intermediate term management of patients with a functional univentricular heart. It improves partial oxygen pressure and the impact of pulsatility on the main pulmonary artery.

Increased systemic cardiac output improves arterial oxygen saturation in bidirectional cavopulmonary shunt

The low arterial oxygen saturation (SaO2) after bidirectional cavopulmonary shunt (BCPS) predicts poor prognosis. The venous oxygen saturation of inferior vena cava (SivcO2), as well as the pulmonary blood flow/systemic blood flow ratio (Q p/Q s) affects the SaO2. The purpose of this study is to determine whether SivcO2 or Q p/Q s should be increased to achieve better outcomes after BCPS. Forty-eight patients undergoing BCPS were included. Data of patients' age and body weight, SivcO2, Q p/Q s, pulmonary artery (PA) pressure and resistance, PA area index, morphology of ventricle, atrioventricular valve regurgitation, and history of PA plasty were collected. Stepwise multiple logistic regression analyses were used to investigate which of the factors most affected the SaO2 after BCPS. There was a significant correlation between SivcO2 and SaO2 (r = 0.771, P < 0.00001). There was no strong correlation between Q p/Q s and SaO2 (r = 0.358, P < 0.05). Stepwise multiple logistic regression analyses revealed that both SivcO2 (r = 0.49, 95 % confidence interval (CI) 0.37-0.62, P < 0.0001) and Q p/Q s (r = 11.1, 95 % CI 3.3-18.9, P = 0.007) most affected SaO2 after BCPS. Since the SivcO2 has a stronger correlation than Q p/Q s with SaO2, despite the fact that both raising Q p/Q s and raising cardiac output can increase SaO2, raising cardiac output should be considered prior to Q p/Q s to raise the SaO2 after BCPS.

Cavopulmonary anastomosis without cardiopulmonary bypass

OBJECTIVES

There is an increasing trend to perform the bidirectional superior cavopulmonary (Glenn) anastomosis without cardiopulmonary bypass. In this report, we present our results of off-pump bidirectional Glenn operation done without using a venoatrial shunt to decompress the superior vena cava during clamping. [corrected].

METHODS

A prospective, non-randomized comparative study was conducted in 50 patients with functional single ventricle anomalies who underwent bidirectional Glenn anastomosis without cardiopulmonary bypass. The patients were divided into two groups: Group I (n = 25), where it was done without a veno-atrial shunt, and Group II (n = 25), where it was done with a veno-atrial shunt. Two patients in Group I and 4 patients in Group II had a bilateral bidirectional Glenn shunt. Five patients in Group I and three patients in Group II had a previous left modified Blalock-Taussig shunt. All patients underwent a complete neurological examination both preoperatively as well as postoperatively.

RESULTS

The early hospital mortality was 4% (2/50), one in each group. The median follow-up was 14 months. The mean internal venous pressure on clamping the superior vena cava was 37.07 ± 7.12 mmHg in Group I and 24 ± 4.4 mmHg in Group II. The mean clamp time was 9.85 ± 3.52 min in Group I and 21.3 ± 4.4 min in Group II. The transcranial pressure gradient was 62.37 ± 15.01 mmHg in Group I, while 65.08 ± 13.89 in Group II. The mean intensive care unit stay was 2.57 ± 75 days in Group I, 3.3 ± 1.09 in Group II. There were no major neurological complications apart from treatable convulsions in one case in Group I (4%), 2 cases in Group II (8%), and delayed recovery in one case (4%) in Group I.

CONCLUSIONS

Off-pump bidirectional Glenn operation without caval decompression is a safe, simple and more economic procedure.

Intact right ventricle-pulmonary artery shunt after stage 2 palliation in hypoplastic left heart syndrome improves pulmonary artery growth

For patients with hypoplastic left heart syndrome who have undergone the Norwood procedure with a right ventricle-pulmonary artery (RV-PA) shunt, the shunt can either be removed or left intact at the time of the stage 2 procedure. This study aimed to determine the effects of an intact shunt on pulmonary artery growth and clinical outcomes after the stage 2 procedure. A retrospective review of patients who underwent Norwood with an RV-PA shunt from 2005 to 2010 was performed. Catheterization data, echocardiographic data, postoperative outcome variables, and mortality data were collected. Pulmonary artery size was measured at pre-stage 2 and pre-Fontan catheterizations using the Nakata Index and the McGoon Ratio. Of the 68 patients included in the study, 48 had the shunt removed at the time of stage 2 (group 1), and 20 had the shunt left intact (group 2). The two groups did not differ in terms of pre-stage 2 hemodynamics or pulmonary artery size. After stage 2, group 2 had higher oxygen saturations. The two groups did not differ regarding duration of chest tube drainage, length of hospital stay, need for unplanned interventions, or mortality. Before Fontan, the group 2 patients had higher superior vena cava (SVC) pressures and more venovenous collaterals closed. There was increased pulmonary artery growth between the pre-stage 2 and pre-Fontan catheterizations in group 2 using both the Nakata Index (+148.5 vs -52.4 mm(2)/m(2); p = 0.01) and the McGoon Ratio (+0.36 vs +0.01; p = 0.01). These findings indicate that patients with an intact RV-PA shunt after stage 2 have greater pulmonary artery growth than patients with the shunt removed, with no increased risk of complications.

Is additional pulsatile pulmonary blood flow beneficial to patients with bidirectional Glenn?

OBJECTIVE

To compare the results of bidirectional Glenn when performed with or without pulsatile pulmonary blood flow in a cohort of patients with a single ventricle.

METHODS

Records of 212 patients undergoing staged single ventricle palliation during a 10-year period were retrospectively reviewed. Of those, 103 (33 in pulsatile group A and 70 in nonpulsatile group B) were selected.

RESULTS

Demographics and pre- and intraoperative variables were comparable for both groups. There was no difference in oxygen saturations immediately after the bidirectional Glenn in the 2 groups. The duration and output of chest tube drainage, incidence of chylothorax, and total length of stay was higher in group A. There was no difference in the number of diuretics or oxygen requirement upon discharge between groups. Pre-Glenn measurements showed a mean McGoon ratio in group A of 1.5 (1.46-1.57) and in group B of 1.59 (1.53-1.7) (P = .11); however, there was a significant difference in the ratio between groups at pre-Fontan measurements: group A, 1.76 (1.73-1.79) and group B, 1.6 (1.53-1.66) (P < .05). At pre-Fontan measurements there was a significant difference in mean pulmonary artery pressure between group A (14 mm [12.8-15.2]) and group B (10 mm [9.7-11]) (P < .05) and a trend toward higher incidence of venovenous collaterals in group A. There was no perioperative or interstage mortality in either group.

CONCLUSIONS

Pulsatile bidirectional Glenn is associated with better pulmonary artery growth, which might improve long-term outcomes after Fontan. However, it was associated with a higher postoperative complication rate.

Outcomes of the bidirectional Glenn procedure in patients less than 3 months of age

OBJECTIVE

The bidirectional Glenn procedure is a well-established procedure performed as part of the single-ventricle palliation pathway. Numerous studies have highlighted the potential benefits of an "early" BDG procedure. The ideal age to perform the BDG procedure, however, remains uncertain. We report our experience with the BDG procedure in patients younger than 3 months.

METHODS

One hundred sixty-nine consecutive patients from 1998 to 2007 undergoing the BDG procedure were divided into 2 groups: younger than 3 months (n = 20) and older than 3 months. The groups were compared for 26 variables. All data were analyzed with Kaplan-Meier survival analysis and the Cox proportional hazard regression test to assess the probability of survival after the BDG procedure in both groups. A stepwise regression analysis was performed for identification of independent factors for postoperative oxygen saturation at hospital discharge.

RESULTS

The groups were comparable, with an equal distribution of patients with right-sided or left-sided single-ventricle anatomy. Although intensive care unit length of stay, ventilation time, and hospital length of stay were longer in the younger group, room air oxygen saturations at discharge, both early and late mortality, and time to the Fontan procedure were similar between groups. The independent variables found for death after the BDG procedure were preoperative mean pulmonary artery pressure, atrioventricular valve regurgitation, and postoperative oxygen saturations at hospital discharge. Survival in patients with hypoplastic left heart syndrome was comparable between groups after 5 years of follow-up.

CONCLUSION

The BDG procedure is feasible and safe in patients as young as 2 months of age, with early and late mortality equivalent to that seen in older patients.

Transcatheter occlusion of antegrade pulmonary flow in children after cavopulmonary anastomosis

OBJECTIVE

To report our experience with transcatheter occlusion of antegrade pulmonary blood flow (APF) for postoperative complications of cavopulmonary anastomosis (BCPA).

BACKGROUND

It has been suggested that limited APF enhances pulmonary arterial growth in patients undergoing BCPA. However, APF may result in suboptimal postoperative hemodynamics and sequelae such as SVC syndrome or prolonged chest tube drainage. For this subgroup, closure of APF may alleviate these problems.

METHODS

All BCPA procedures where APF was left open from 1995-2005 were reviewed. Symptomatic patients with APF who underwent a cardiac catheterization in the postoperative period comprised the study cohort.

RESULTS

179 BCPA procedures were performed during the study period. APF was left patent in 29/179. 6/29 patients (age 10-28 months, median 14 months) presented 12 to 130 day; (median 31 days) with persistent pleural effusions (5) or SVC syndrome (1, Five had a history of a previous pulmonary arterial band (PAB) and one pulmonary stenosis. PA pressure was elevated in all (range 17-27 mmHg; median 22 mmHg). Hemodynamic evaluation with temporary APF occlusion was repeated in all patients. APF was successfully closed in 4/6 patients. The Amplatzer POA occluder was used in 3 and the Amplatzer ASD occluder in 1. Pulmonary effusions resolved in all the patients who had transcatheter APF closure as did the case of SVC syndrome. There were no complications.

CONCLUSION

Transcatheter APF occlusion seems both safe and feasible in patients with hemodynamic compromise following BCPA with residual APF. Temporary occlusion testing prior to permanent device closure is recommended.

Comparative outcome of bidirectional Glenn shunt in patients with pulmonary vascular resistance > or = 3.5 woods units versus < 3.5 woods units

Moderate to severe pulmonary hypertension is considered to be an absolute contraindication to the performance of bidirectional Glenn (BDG) shunting. However, BDG shunting has been performed in young children with pulmonary hypertension associated with unrestricted pulmonary blood flow. In this study, the medical records of patients who underwent BDG starting from October 2000 to March 2004 were reviewed. Patients were divided into 2 groups on the basis of indexed pulmonary vascular resistance (PVRI) measured in room air: a high-risk group (n = 12) with PVRI > or = 3.5 Woods units (WU)/m(2) and a low-risk group (n = 28) with PVRI <3.5 WU/m(2) in room air. The 2 groups were comparable with respect to age, weight, ventricular morphology, pulmonary arterial anatomy, and atrioventricular valve function. Mean pulmonary arterial pressure and PVRI were significantly higher in the high-risk group compared with the low-risk group (39.2 +/- 20.7 vs 15.1 +/- 6.25 mm Hg, p <0.002, and 6.0 +/- 2.5 vs 1.6 +/- 0.82 WU/m(2), p <0.0005, respectively). The ratio of pulmonary flow to systemic flow was 1.45 +/- 0.76 in the high-risk group and 1.24 +/- 1.2 in the low-risk group. In the high-risk group, mean PVRI decreased to 2.0 +/- 1.0 WU/m(2) on 100% oxygen (p <0.0005). A contraindication to Glenn shunting was PVRI >3.5 WU/m(2) on 100% oxygen. Hospital mortality was 17% (2 of 12) in the high-risk group and 4% (1 of 28) in the low-risk group. Of 10 survivors in the high-risk group, 1 had undergone a Kawashima procedure, 7 had undergone Fontan procedures (with 1 death), and 2 were awaiting the completion of Fontan procedures as of this writing. In conclusion, these preliminary data suggest that in young children with increased pulmonary flow, BDG shunting can be safely performed, despite the apparent elevation of pulmonary arterial pressure to inoperable levels, provided PVRI decreases to < or = 3.5 WU/m(2) on 100% oxygen.

Bidirectional Glenn and antegrade pulmonary blood flow: temporary or definitive palliation?

BACKGROUND

We sought to investigate the role of the bidirectional Glenn with antegrade pulmonary blood flow in the surgical history of children with univentricular hearts.

METHODS

A series of 246 patients, from three joint institutions, having univentricular heart with restricted but not critical pulmonary blood flow received a bidirectional cavopulmonary shunt with additional forward pulmonary blood flow. All patients have been studied according to their progression, or not, to Fontan operation. Two hundred and eight (84.5%) patients underwent bidirectional cavopulmonary anastomosis as primary palliation. Twenty patients (8.1%) with previous pulmonary artery banding were also enrolled in the study. Patients who had received additional pulmonary blood flow through a previous systemic to pulmonary artery shunt for the critical pulmonary blood flow were excluded.

RESULTS

No in-hospital death occurred. Follow-up was complete at 100%. Mean follow-up was 4.2 +/- 2.8 years (range, 6 months to 7 years). During the observational period 73 (29.7%) patients, considered optimal candidates, underwent Fontan completion for increasing cyanosis and (or) hematocrit and (or) fatigue with exertion. Three patients expired after total cavopulmonary connection (3 of 73; 4.1% mortality rate). The remaining 173 (70.3%) patients are alive with initial palliation. All patients were still well palliated with an arterial oxygen saturation at rest about 90%.

CONCLUSIONS

According to our experience and results, bidirectional Glenn with antegrade pulmonary blood flow may be an excellent temporary palliation prior to a Fontan operation, which can be performed at the onset of symptoms. Bidirectional Glenn may also be the best possible palliation for a suboptimal candidate for Fontan.

Persistent antegrade pulmonary blood flow post-glenn does not alter early post-Fontan outcomes in single-ventricle patients

BACKGROUND

The bidirectional Glenn cavopulmonary anastomosis (BDG) represents the standard interim procedure in treatment of patients with single-ventricle physiology. Anterograde pulmonary blood flow (APBF) maintained after BDG has been shown both to improve and to complicate postoperative clinical course. We studied its effects on outcome after BDG and eventual Fontan completion.

METHODS

From November 1995 to November 2005, 60 patients underwent BDG and Fontan. All patients had APBF from the ventricle to the pulmonary artery at time of BDG. In group 1 (n = 39) APBF was maintained after BDG, whereas APBF was interrupted at BDG in group 2 (n = 21). Cardiac catheterization data, interstage morbidity, and postoperative outcome variables were recorded.

RESULTS

Pre-BDG hemodynamics differed only in that the mean pulmonary artery pressure was higher in group 2 (17.0 +/- 4.4 mm Hg) than in group 1 (13.8 +/- 4.5 mm Hg; p = 0.03). There were no differences between groups 1 and 2 in BDG outcome variables. At pre-Fontan catheterization, group 1 had higher mean pulmonary artery pressure (13.3 versus 10.9 mm Hg, p = 0.01), arterial oxygen saturation (85.8 versus 80.9%, p = 0.0001), and fewer collateral vessels were coil embolized than in group 2 (0.9 versus 1.6, p = 0.02). Mean ventricular end-diastolic pressure was similar between groups. The Nakata index in group 1 remained stable from pre-BDG to pre-Fontan (348 versus 391, p = 0.24), but it decreased in group 2 (375 versus 227, p = 0.046).

CONCLUSIONS

Patients with anterograde pulmonary blood flow after BDG had a modest increase in pulmonary artery growth and arterial oxygen saturations, and decreased collateral vessel formation. This did not, however, confer additional benefit on outcome after BDG or on eventual Fontan completion.

Management of systemic venous anomalies in the pediatric cardiovascular surgical patient

Systemic venous anomalies are rare and heterogeneous entities. Although these anomalies are rare in the general population, they occur more frequently in the subpopulation with congenital heart disease. In and of themselves, most of these lesions have no physiologic significance. However, in the setting of congenital heart disease these lesions may significantly alter surgical treatment. This review is dedicated to these lesions.

Pulmonary artery growth fails to match the increase in body surface area after the Fontan operation

OBJECTIVE

To evaluate the growth of the pulmonary arteries after a Fontan procedure.

DESIGN

Retrospective review.

SETTING

Two paediatric cardiology tertiary care centres.

PATIENTS

61 children who underwent a modified Fontan operation and had angiography suitable for assessment of pulmonary artery size before the Fontan procedure and during long term follow up. An atriopulmonary connection (APC) was present in 23 patients (37.7%) and a total cavopulmonary connection (TCPC) was present in 38 (62.3%). Postoperative angiograms were performed 0.5-121 months (median 19 months) after the Fontan operation.

MAIN OUTCOME MEASURE

Growth of each pulmonary artery measured just before the first branching point. The diameter was expressed as a z score with established nomograms used to standardise for body surface area.

RESULTS

The mean change in the preoperative to postoperative z scores of the right pulmonary artery was -1.06 (p = 0.004). The mean change in the preoperative to postoperative z scores of the left pulmonary artery was -0.88 (p = 0.003). Changes in the preoperative to postoperative z scores were more pronounced in the patients undergoing APC than TCPC, especially for the right pulmonary artery.

CONCLUSION

After the Fontan operation, growth of the pulmonary arteries often fails to match the increase in body surface area.

Additional Pulmonary Blood Flow Has No Adverse Effect on Outcome After Bidirectional Cavopulmonary Anastomosis

BACKGROUND

Controversy continues over whether additional sources of pulmonary blood flow are beneficial in combination with a bidirectional cavopulmonary anastomosis. We have therefore assessed the effects of additional pulmonary blood flow on outcome after bidirectional cavopulmonary anastomosis.

METHODS

From 1996 to 2000, 106 patients underwent bidirectional cavopulmonary anastomosis, either isolated (group 1, n = 54), or with additional pulmonary blood flow through the pulmonary artery (group 2, n = 30) or a Blalock-Taussig shunt (group 3, n = 22).

RESULTS

Superior vena cava syndrome was more frequent in group 2 and less in groups 1 and 3 (p < 0.05). Low-output syndrome was more frequent in group 2 and less in group 3 (p = 0.01). Repeated-measures analysis of variance showed higher oxygen saturations with additional pulmonary blood flow (p < 0.05) and significant changes over time (p < 0.0001). Pulmonary pressures, systemic ventricular fractional shortening, end-diastolic diameter index, end-diastolic pressure, and atrioventricular valve regurgitation remained unaffected by additional pulmonary blood flow. Pulmonary artery pressures were lower in group 2 than 3 (p < 0.05). Fractional shortening (p < 0.05) and atrioventricular valve regurgitation (p < 0.0001) changed significantly over time. Fractional shortening showed a strong trend toward different changing patterns with or without additional pulmonary blood flow (p = 0.055), and atrioventricular valve regurgitation showed different changing patterns among the groups (p < 0.005). End-diastolic diameter and pulmonary artery dimensions, which were smaller than normal, remained unchanged. In logistic regression, smaller body surface area at bidirectional cavopulmonary anastomosis, single ventricle, and bidirectional cavopulmonary anastomosis with a Blalock-Taussig shunt were associated with early death. Actuarial survival including total cavopulmonary connection did not differ among groups (p = 0.96).

CONCLUSIONS

We conclude that additional pulmonary blood flow has no adverse effect on outcome after cavopulmonary anastomosis. Additional flow through the main pulmonary artery offers different advantages and disadvantages concerning perioperative complications and pulmonary artery growth compared with additional flow through a Blalock-Taussig shunt.

The biological "scrabble" of pulmonary arteriovenous malformations: considerations in the setting of cavopulmonary surgery

Pulmonary arteriovenous fistulas are vascular malformations, which, by virtue of producing abnormal vascular connections proximal to the units of gas exchange, result in intrapulmonary right-to-left shunting. These malformations or fistulas reflect at least in part disordered angiogenesis, and less commonly recruitment and dilation of pre-existing vascular channels. Pulmonary arteriovenous fistulas occur in a number of diverse clinical settings. Such fistulas are a well-established feature of the Weber-Osler-Rendu complex, or hereditary haemorrhagic telangiectasia, an autosomal dominant vascular dysplasia characterized by mucocutaneous telangiectasis, epistaxis, gastrointestinal haemorrhage, and arteriovenous malformations in the lung, brain, liver and elsewhere. They are also seen in the patient with acute or chronic liver disease, disease that is usually but not invariably severe, or those with non-cirrhotic portal hypertension. They may occur as congenital malformations, single or diffuse, large or small in isolation, and when large or extensive enough may result in hypoxaemia, clinical cyanosis, and heart failure. Cerebral vascular accidents are also a well-known complication of this disorder. An extensive literature has accumulated with regard to the pulmonary arteriovenous fistulas seen in the setting of the Weber-Osler-Rendu complex, and there is considerable information on the genetics, basic biology, clinical findings, complications and therapeutic interventions of these malformations in the setting of this syndrome. These issues, however, are not the primary considerations of this review, although some aspects of this fascinating disorder will be discussed later. Rather the focus will be on pulmonary arteriovenous malformations that develop in the setting of cavopulmonary surgery, and their relationship to the pulmonary arteriovenous fistulas occurring in the hepatopulmonary syndrome. The complex tapestry of these overlapping and intersecting clinical observations will be unfolded in the light of their chronology.

Effects of controlled antegrade pulmonary blood flow on cardiac function after bidirectional cavopulmonary anastomosis

BACKGROUND

Bidirectional cavopulmonary anastomosis (BCPA) has been used as an intermediate stage in the treatment of patients with single-ventricle physiology. Leaving additional antegrade pulmonary blood flow has been shown to improve postoperative arterial blood oxygen saturations; however, controversy continues over whether the potential increase in systemic venous pressure is detrimental. We studied the effects of controlled antegrade pulmonary blood flow on cardiac function in patients after BCPA.

METHODS

From January 1993 to July 2000, 128 patients underwent BCPA. Mean age at operation was 6.2 +/- 4 months (range 2 to 36 months). In group 1 (n = 72), restricted antegrade pulmonary blood flow was maintained through a native narrowed pulmonary valve or by adjustment of previously placed pulmonary artery band with the goal of maintaining the mean pulmonary artery pressure less than 16 mm Hg. In group 2 (n = 56), BCPA was the only source of pulmonary blood flow.

RESULTS

One hospital death (0.8%) occurred. The mean pulmonary artery pressure at the end of the operation was 13 +/- 2 mm Hg in group 1 compared with 12 +/- 2 mm Hg in group 2, a difference that was not significant. Patients in group 1 had higher arterial oxygen saturations (84% +/- 3% compared with 74% +/- 3% in group 2, p < 0.05), and shorter mean hospital stay (9 +/- 3 days compared with 15 +/- 2 days, p < 0.05). Persistent pleural effusion (> 10 days) or late chylothorax occurred in 4 patients from group 1 and 3 from group 2, a difference that was not significant. During a mean follow-up of 36 +/- 10 months no late deaths occurred. The mean oxygen saturation remained higher in group 1, 80% +/- 3% compared with 74% +/- 4% in group 2, and the hematocrit was lower, at 38% +/- 3% compared with 46% +/- 4% (p < 0.05 for both comparisons). Cardiac catheterizations were performed in 68 patients before completion Fontan. Total pulmonary artery (Nakata) index was 263 +/- 34 mm(2)/m(2) in group 1 (n = 40) and 188 +/- 13 mm(2)/m(2) in group 2 (n = 28) (p < 0.05). The mean pulmonary artery pressure and mean ventricular end-diastolic pressure were similar.

CONCLUSIONS

Controlled antegrade pulmonary blood flow may have favorable effects on cardiac function for a selected group of patients and does not appear to have adverse effects on subsequent suitability for completion Fontan.

Hypoventilation improves oxygenation after bidirectional superior cavopulmonary connection

OBJECTIVE

Bidirectional superior cavopulmonary connection may be complicated by systemic hypoxemia. Previous work has shown that hyperventilation worsens systemic oxygenation in patients after bidirectional superior cavopulmonary connection. The likely mechanism is that hyperventilation-induced hypocarbia decreases cerebral, superior vena caval, and pulmonary blood flow. The aim of the current study was to determine whether the converse approach, hypoventilation, improves oxygenation after bidirectional superior cavopulmonary connection.

METHODS

This is a prospective, patient-controlled study of 15 patients (median age 8.0 months, range 4.7-15.5) who underwent bidirectional superior cavopulmonary connection. Patients were studied in the intensive care unit, within 8 hours of surgery, while sedated, paralyzed, and mechanically ventilated. To avoid acidosis during hypoventilation, sodium bicarbonate was administered before hypoventilation. Cerebral blood flow velocity was measured by transcranial Doppler sonography of the middle cerebral artery.

RESULTS

Hypoventilation following administration of sodium bicarbonate (pH-buffered hypoventilation) produced hypercarbia (mean Pco(2) = 58 mm Hg versus 42 mm Hg at baseline). During hypoventilation, there were significant increases in both mean arterial Po(2) (from 50 mm Hg at baseline to 61 mm Hg; P <.05) and mean systemic oxygen saturation (from 86% at baseline to 90%; P <.05). These increases occurred despite accompanying, small increases in pulmonary artery pressure and transpulmonary gradient. Hypoventilation also produced an increase in mean cerebral blood flow velocity (from 37 cm/s at baseline to 55 cm/s; P <.05) and a decrease in the arteriovenous oxygen saturation difference across the upper body (from 33% at baseline to 23%; P <.05), consistent with increased cerebral blood flow.

CONCLUSIONS

This study demonstrates that hypoventilation improves systemic oxygenation in patients after bidirectional superior cavopulmonary connection. The likely mechanism for this effect is that hypoventilation-induced hypercarbia decreases cerebral vascular resistance, thus increasing cerebral, superior vena caval, and pulmonary blood flow. Hypoventilation may be a useful clinical strategy in patients who are hypoxemic in the early postoperative period after bidirectional superior cavopulmonary connection.

[The bidirectional Glenn operation in 100 cases with complex congenital heat diseases: factors influencing surgical results]

OBJECTIVE

The bidirectional Glenn shunt is a well established surgical technique in children with complex congenital heart disease. The present study is a retrospective analysis of patients undergoing this operation in order to assess the influence of different variables in the outcome.

PATIENTS AND METHOD

From December 1990 to June 2000, 100 patients received a bidirectional Glenn shunt. Two groups were defined, based on the outcome. Group A (n = 15, unsuccessfully result) including death and need to reoperate, and Group B (n = 85, patients with good outcome).

RESULTS

The mortality was 8%. Eight patients were reoperated at follow-up. The survivors were followed for a mean of 3.5 years. Mean pulmonary artery pressure 7 mmHg was a factor associated with poor clinical progress. Other variables (age less than 1 year, excessive pulmonary blood flow, double Glenn operation, significant anatomic anomalies, and arrythmias), were also associated with outcome. Significant variations were observed in the time of by-pass or the need for aortic clamp in cases with simultaneous operative repair of pulmonary branch stenosis. Actuarial survival rate, most more than 1 year was 92%, and freedom from reoperation at 3 years was 90%.

CONCLUSIONS

The bidirectional Glenn shunt is an excellent palliation in patients with functionally single ventricle. Mean pulmonary artery pressure was the most important variable related with the outcome. We are encouraged to continue with tendency to perform bidirectional Glenn shunt preferably early, avoiding, whenever possible, previous palliative surgery.

Synchronized independent lung ventilation in palliated congenital heart disease with variable sources of pulmonary blood flow

OBJECTIVE: Presentation of two patient studies demonstrating the use of synchronized independent lung ventilation in the management of acute respiratory failure in patients with complex palliated congenital heart disease and variable sources of pulmonary blood flow. DESIGN: Clinical course of two patients. SETTING: Cardiac intensive care unit in a tertiary care, university-affiliated pediatric teaching hospital. PATIENTS: Patient 1 was a 22-yr-old woman with a single ventricle and right lung blood flow supplied by a classic Glenn shunt and left lung blood flow through a systemic-to-pulmonary artery shunt. Patient 2 was a 12-yr-old boy with tetralogy of Fallot and complete common atrioventricular canal defect with right lung blood flow supplied by a classic Glenn shunt and left lung blood flow supplied by the right ventricle. Both patients presented with acute, left-sided lung disease and hypoxemia. INTERVENTIONS: We used selective bronchial intubation via a double-lumen tracheal tube with a bronchial extension for synchronized independent lung ventilation to permit high-pressure ventilation of the abnormal left lung low-pressure ventilation of the normal right lung supplied by a Glenn shunt. Inhaled nitric oxide was administered to both patients and continued in one when improved oxygenation was observed. MEASUREMENTS AND MAIN RESULTS: Serial arterial blood gas measurements, mechanical indices of pulmonary function, and chest radiographs were closely followed. Synchronized independent lung ventilation contributed to improvements in systemic arterial blood oxygenation and alveolar ventilation allowing resumption of conventional ventilation in both patients. No adverse effects related to bronchial tube placement or maintenance occurred. CONCLUSION: Independent lung ventilation is an effective means of isolating the two lungs for differential ventilation, as well as the selective delivery of inhaled medications. In patients with unilateral lung disease and a Glenn shunt supplying the unaffected lung, selective lung ventilation allows aggressive treatment of the abnormal lung while optimizing flow through the Glenn shunt to maximize effective pulmonary blood flow, systemic oxygenation, and hemodynamics.