Hemidiaphragmatic paralysis increases postoperative morbidity after a modified Fontan operation

In a porcine model of implantable pacemakers for pediatric unilateral diaphragm paralysis, the phrenic nerve is the best target

BACKGROUND

A frequent complication of Fontan operations is unilateral diaphragmatic paresis, which leads to hemodynamic deterioration of the Fontan circulation. A potential new therapeutic option is the unilateral diaphragmatic pacemaker. In this study, we investigated the most effective stimulation location for a potential fully implantable system in a porcine model.

METHODS

Five pigs (20.8 ± 0.95 kg) underwent implantation of a customized cuff electrode placed around the right phrenic nerve. A bipolar myocardial pacing electrode was sutured adjacent to the motor point and peripherally at the costophrenic angle (peripheral diaphragmatic muscle). The electrodes were stimulated 30 times per minute with a pulse duration of 200 µs and a stimulation time of 300 ms. Current intensity was the only variable changed during the experiment.

RESULTS

Effective stimulation occurred at 0.26 ± 0.024 mA at the phrenic nerve and 7 ± 1.22 mA at the motor point, a significant difference in amperage (p = 0.005). Even with a maximum stimulation of 10 mA at the peripheral diaphragm muscle, however, no effective stimulation was observed.

CONCLUSION

The phrenic nerve seems to be the best location for direct stimulation by a unilateral thoracic diaphragm pacemaker in terms of the required amperage level in a porcine model.

Pulmonary blood flow in children with univentricular heart and unilateral diaphragmatic paralysis

OBJECTIVES

Spontaneous breathing has an important effect on pulmonary arterial blood flow in patients with Glenn/Fontan circulation. Unilateral diaphragmatic paralysis (DP) is a frequent complication after heart surgery in congenital heart disease. The aim of this study was to investigate the influence of unilateral DP on blood flow distribution in the pulmonary arteries with Glenn/Fontan circulation.

METHODS

Magnetic resonance phase-contrast imaging was used to evaluate stroke volume index (SVI) in the left and right pulmonary arteries in patients with Glenn/Fontan circulation with unilateral DP. Data for 18 patients with univentricular heart and unilateral DP were analysed, 8 in the Glenn stage and 10 in the Fontan stage. Ten patients had right-sided DP, and 8 had left-sided DP. A diaphragmatic plication was performed in 7 patients. The control group consisted of 36 patients with Glenn (n = 16)/Fontan (n = 20) circulation without DP.

RESULTS

In both left- and right-sided DP, the SVI to the ipsilateral side was significantly lower than in controls [2.81 (1.45-4.50) ml/m2 left vs 11.97 (7.36-16.37) ml/m2 in controls, P < 0.0002; 8.2 (4.49-12.64) ml/m2 with right vs 12.64 (9.66-16.61) ml/m2 in controls; P = 0.0284]. The SVI to the contralateral side showed a slight but non-significant increase in the presence of unilateral DP.

CONCLUSIONS

Unilateral DP in patients with Glenn/Fontan circulation has a negative impact on pulmonary arterial SVI on the side of the paralysis.

Plication for diaphragm paralysis after paediatric cardiac surgery: a single-centre experience

OBJECTIVE

Diaphragm paralysis is a well-known complication following surgery for CHDs, which increases morbidity, mortality, and length of hospital stay as well as costs. Herein, we present our experience with diaphragm plication following paralysis of the phrenic nerve encountered after paediatric cardiac surgery.

METHODS

This study retrospectively reviewed the medical records of 23 diaphragm plications in 20 patients who underwent paediatric cardiac surgery between January 2012 and January 2022. The patients were carefully selected based on aetiology and a combination of clinical manifestation and chest imaging characteristics including chest X-ray, ultrasonography, and fluoroscopy.

RESULTS

Twenty-three successful plications were performed in 20 patients (15 males and 5 females) out of a total of 1938 operations performed in our centre. Mean age and body weight were 18.2 ± 17.1 months and 8.3 ± 3.7 kg, respectively. The period between the cardiac surgery and diaphragmatic plication was 18.7 ± 15.1 days. The highest incidence of diaphragm paralysis was encountered in systemic to pulmonary artery shunt patients with 7 out of 152 patients (4.6%). Any mortality was not encountered during a mean follow-up period of 4.3 ± 2.6 years.

CONCLUSIONS

Early results of plication of the diaphragm following phrenic nerve palsy in symptomatic patients who underwent paediatric cardiac surgery are encouraging. Evaluation of the diaphragmatic function should be a routine part of post-operative echocardiography. Diaphragm paralysis may be a consequence of dissection, contusion, stretching, and thermal injury both in terms of hypothermia and hyperthermia.

Fontan procedure on deep hypothermic circulatory arrest: Short-term results and technique

Background

Various operative strategies are described for the Fontan procedure. In this study, we describe our short-term results and technique of Fontan procedure on cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA).

Methods

This was a retrospective study of 32 patients, median age of 6 years (4-19 years) and median weight of 20 kg (13-51 kg), who underwent Fontan procedure on CPB and DHCA from July 2016 to July 2021.

Results

The median CPB time was 125 min (77-186 min), the median DHCA time was 42 min (27-50 min), and the median Fontan pressure was 14 mmHg (10-18 mmHg). The median time to extubation was 4 h (1-20 h), the duration of chest tube drainage was 8 days (5-24 days), and the median intensive care unit stay was 4 days (3-8 days). The presence of heterotaxy was associated with longer duration of pleural drainage (P = 0.01). There was no operative mortality and no major adverse events such as seizures, gross neurological deficits, or arrhythmias in the postoperative period.

Conclusions

Fontan procedure can be safely performed on CPB and DHCA with good operative results. This operative strategy may be used in special circumstances like in patients with situs and systemic venous anomalies and those requiring repair of a complex intracardiac defect. Long-term follow-up will be required to evaluate if this strategy has any impact on the neurodevelopmental outcome and the long-term sequelae of Fontan.

Reappraisal of lung manifestations in the setting of Fontan circulation

Fontan circulation is a well-established palliation in patients with functional single ventricles. Absence of a sub-pulmonary pumping chamber creates a unique physiology in which blood flow is mainly guided by negative intrathoracic and elevated central venous pressures. Various pulmonary anatomic or pathophysiologic changes can jeopardize optimal Fontan circulation. Long-term survival of patients who have undergone the contemporary total cavopulmonary connection is satisfactory. Thorough literature review in conjunction with accumulated clinical experience can lead clinicians to extract conclusions regarding Fontan and lung interactions indicating the purpose of this review.

Diaphragm Paralysis After Pediatric Cardiac Surgery: An STS Congenital Heart Surgery Database Study

BACKGROUND

Previous single-center studies of diaphragm paralysis (DP) after pediatric cardiac surgery report incidence of 0.3% to 12.8% and associate DP with respiratory complications, prolonged ventilation and length of stay, and mortality. To better define incidence and associations between DP and various procedures and outcomes, we performed a multicenter study.

METHODS

The Society of Thoracic Surgeons Congenital Heart Surgery Database was queried to identify children who experienced DP after cardiac surgery (2010-2018; 126 centers). Baseline characteristics and postoperative outcomes were compared between patients with and without DP as well as between patients who underwent plication and those who did not. Associations between center volume and center rates of DP and use of plication were also explored.

RESULTS

A total of 2214 of 191,463 (1.2%) patients experienced DP. Postoperative DP portended worse outcomes, including mortality (5.6% vs 3.5%; P < .001), major morbidity (37.2% vs 10.7%; P < .001), tracheostomy (7.1% vs 0.9%; P < .001), prolonged mechanical ventilation (38.0% vs 7.8%; P < .001), and 30-day readmission (22.0% vs 10.6%; P < .001). A total of 1105 of 2214 (49.9%) patients with DP underwent plication. Patients who underwent plication were younger, were smaller, had more risk factors, and underwent more complex surgeries. Plication rates varied widely across centers. There was no correlation between center volume and center risk-adjusted rates of DP (r = .05, P = .5), nor frequency of plication (r = .08, P = .4).

CONCLUSIONS

DP complicating pediatric heart surgery is rare but portends significantly worse outcomes. One-half of patients underwent plication. Center-level risk-adjusted rates of DP and plication are not associated with case volume. Significant variability in plication practices suggests a target for quality improvement.

Impact of prior diaphragm plication on subsequent stages of single ventricle palliation

BACKGROUND

Phrenic nerve injury is a known cause of morbidity after single ventricle palliation. Previous studies have shown that hemidiaphragm plication improves short-term outcomes. The effect of plication on the outcomes of subsequent stages of single ventricle palliation is unknown.

METHODS

From 1997 to 2015, 1146 patients underwent surgical management of single ventricle physiology at our institution. We reviewed the records of 30 patients who had undergone diaphragm plication for phrenic nerve injury before Fontan completion. Each patient was compared with 2 propensity-matched controls identified from patients who underwent the Glenn or Fontan procedure during the same period without diaphragm plication. Propensity matching was achieved for each test subject using the nearest neighbor algorithm. Data are presented as the median and quartiles or numbers and percentages.

RESULTS

The cohort included 18 boys (60%). Of the 30 patients, 19 (63%) had undergone plication after first-stage palliation. Of these, 13 have undergone completion Fontan, 5 were awaiting Fontan at the last follow-up, and 1 had died. An additional 11 patients had undergone plication after Glenn and proceeded to Fontan completion. Thus, 24 patients with diaphragm plication have undergone Fontan completion. No difference was found in pulmonary pressure or resistance between the plicated patients and their propensity-matched controls. Both groups had comparable chest tube output and hospital lengths of stay. Equal proportions of patients in both groups required pulmonary vasodilator therapy and/or supplemental oxygen at hospital discharge.

CONCLUSIONS

Prior diaphragm plication does not adversely affect Fontan completion in children with single ventricle physiology. The hospital course during subsequent stages of palliation for plicated patients was no different than that of matched controls.

Unilateral diaphragmatic paralysis associated with surgical mitral valve repair in dogs

OBJECTIVES

Unilateral diaphragmatic paralysis (UDP) due to phrenic nerve injury is a potential complication of thoracic surgery. This study evaluated the prevalence of UDP associated with surgical mitral valve repair (MVR) and its effect on surgical outcomes in dogs.

ANIMALS, MATERIALS AND METHODS

Two hundred ninety-four dogs that underwent MVR were included in the study. A retrospective review of medical records was performed for dogs surviving surgery. Diagnosis of UDP was based on preoperative and postoperative thoracic dorsoventral radiographs.

RESULTS

A total of 284 dogs survived until the day after surgery. The prevalence of UDP on the day after surgery, on the day of discharge, and after the first postoperative month was 30%, 24%, and 9%, respectively. One case of UDP was observed at 3 months after surgery. Unilateral diaphragmatic paralysis was exhibited by nine of the 21 patients that died in the hospital. The proportion of patients with UDP was higher in dogs that died of respiratory failure than in dogs that died of other causes (p = 0.002). Most dogs whose deaths were suspected to have been related to respiratory failure also had pre-existing respiratory diseases. The occurrence of UDP did not relate to the lengths of stay in the intensive care unit or the hospital.

CONCLUSIONS

Our findings suggest that UDP is a common complication in dogs after MVR and that the prevalence of UDP decreases with time after surgery. Unilateral diaphragmatic paralysis is a risk factor for postoperative death, especially in patients with pre-existing respiratory disease.

Impact of Phrenic Nerve Palsy on Late Fontan Circulation

BACKGROUND

Although adverse effects of phrenic nerve palsy (PNP) on early Fontan circulation have been reported, detailed late impact remains unclear.

METHODS

Of 218 patients undergoing extracardiac total cavopulmonary connection between 1995 and 2008, 160 who all underwent cardiac catheter examination, spirometry, and exercise capacity testing 10 years after the operation were enrolled. The cohort was divided into 2 groups: with (N = 21) or without PNP (control group, N = 139). The patients with PNP were further divided into the recovered PNP group (n = 10) and the persistent PNP group (n = 11). All but 2 patients who developed PNP (90.9%) underwent diaphragmatic plication. There was no difference in hemodynamic indices at pre-Fontan evaluation among the three groups.

RESULTS

Ten years after the Fontan procedure, the averaged forced vital capacity was 81% ± 18% of predicted in the control group, 86% ± 17% in the recovered PNP group, and 56% ± 12% in the persistent PNP group (P < .001). Peak oxygen consumption was linearly correlated to the forced vital capacity (r = 0.222, P = .009). There was no significant difference in the peak oxygen consumption between groups. Significant veno-venous collaterals into the diaphragm from lower body to pulmonary vein(s) or atria more frequently developed in patients who underwent diaphragmatic plication compared with those who did not (P < .001).

CONCLUSIONS

Persistent PNP resulted in reduced forced vital capacity; however, its influence on exercise intolerance could not be identified. Diaphragmatic plication should be reserved for patients who experience clinically significant respiratory or hemodynamic sequelae of PNP.

A restrictive ventilatory pattern is common in patients with univentricular heart after Fontan palliation and associated with a reduced exercise capacity and quality of life

AIM

The Fontan circulation is highly dependent on ventilation, improving pulmonary blood flow and cardiac output. A reduced ventilatory function is reported in these patients. The extent of this impairment and its relation to exercise capacity and quality of life is unknown and objective of this study.

METHODS

This multicenter retrospective/cross-sectional study included 232 patients (140 females, age 25.6 ± 10.8 years) after Fontan palliation (19.8% atrioventricular connection; 20.3% atriopulmonary connection; 59.9% total cavopulmonary connection). Resting spirometry, cardiopulmonary exercise tests, and quality-of-life assessment (SF-36 questionnaire) were performed between 2003 and 2015.

RESULTS

Overall, mean forced expiratory volume in one second (FEV₁ ) was 74.7 ± 17.8%predicted (%pred). In 59.5% of the patients, FEV₁ was <80%pred., and all of these patients had FEV₁ /forced vital capacity (FVC) > 80%, suggestive of a restrictive ventilatory pattern. Reduced FEV₁ was associated with a reduced peakVO₂ of 67.0 ± 17.6%pred. (r = 0.43, P < .0001), even if analyzed together with possible confounding factors (sex, BMI, age, years after palliation, number of interventions, scoliosis, diaphragmatic paralysis). Synergistically to exercise capacity, FEV₁ was associated to quality of life in terms of physical component summary (r = 0.30, P = .002), physical functioning (r = 0.25, P = .008), bodily pain (r = 0.22, P = .02), and general health (r = 0.16, P = .024). Lower FEV₁ was associated with diaphragmatic paralysis (P = .001), scoliosis (P = .001), higher number of interventions (P = .002), and lower BMI (P = .01). No correlation was found to ventricular morphology, type of surgeries, or other perioperative/long-term complications.

CONCLUSIONS

This study shows that the common restrictive ventilatory pattern in Fontan patients is associated with lower exercise capacity and quality of life. Risk factors are diaphragmatic paralysis, scoliosis, a high total number of interventions and low BMI.

Impact of Phrenic Nerve Palsy and Need for Diaphragm Plication Following Surgery for Pulmonary Atresia With Ventricular Septal Defect and Major Aortopulmonary Collaterals

Injury to the phrenic nerves may occur during surgery for pulmonary atresia with ventricular septal defect and major aortopulmonary collateral arteries (PA-VSD and MAPCAs). These patients may develop respiratory failure and require diaphragm plication. The purpose of this study was to evaluate the impact of phrenic nerve palsy on recovery following surgery for PA-VSD and MAPCAs. Between 2007 and 2016, approximately 500 patients underwent surgery for PA-VSD and MAPCAs at our institution. Twenty-four patients (4.8%) subsequently had evidence of new phrenic nerve palsy. Sixteen patients were undergoing their first surgical procedure, whereas 8 were undergoing reoperations. All 24 patients underwent diaphragm plication. A cohort of matched controls was identified based on identical diagnosis and procedures but did not sustain a phrenic nerve palsy. Eighteen of the 24 patients (75%) had clinical improvement following diaphragm plication as evidenced by the ability to undergo successful extubation (5 ± 2 days), transition out of the intensive care unit (32 ± 16 days), and discharge from the hospital (42 ± 19 days). In contrast, there were 6 patients (25%) who did not demonstrate a temporal improvement following diaphragm plication, as evidenced by intervals of 61 ± 38, 106 ± 45, and 108 ± 46 days, respectively (P < 0.05 for all 3 comparisons). The 6 patients who failed to improve following diaphragm plication had a significantly greater number of comorbidities compared to the 18 patients who demonstrated improvement (2.2 vs 0.6 per patient, P < 0.05). When compared with the control group, patients who improved following diaphragm plication spent an additional 22 days and patients who failed to improve an additional 90 days in the hospital. The data demonstrate a bifurcation of clinical outcome in patients undergoing diaphragm plication following surgery for PA-VSD and MAPCAs. This bifurcation appears to be linked to the presence or absence of other comorbidities.

Contributions of Respiration and Heartbeat to the Pulmonary Blood Flow in the Fontan Circulation

BACKGROUND

In the Fontan circulation, driving forces with respiration, heartbeat, and lower limb muscle pump are relevant. However, the mechanics of these forces has not been proven, and their effects on the Fontan circulation remain unclear.

METHODS

We performed catheter examinations and measured pressure and flow velocity simultaneously in the bilateral pulmonary arteries of 12 Fontan patients 1 year after the operation. The pulmonary pressure and flow velocity data were decomposed into respiratory and heartbeat components by discrete Fourier analysis. We then calculated respiratory and cardiac wave intensity (WI) based on the respiratory and heartbeat components of pressure and flow velocity data.

RESULTS

Respiratory WI formed 2 negative peaks, a backward expansion wave during the inspiratory phase, and then a backward compression wave during the expiratory phase. In 2 phrenic nerve palsy cases and 1 case of a patient on a respirator, respiratory WI showed disturbed patterns and a negative pattern, respectively. Cardiac WI showed 2 or 4 negative peaks, the time phase of which matched that of the atrial contractions.

CONCLUSIONS

WI analysis elucidated that inspiration acts as a sucking driving force and increases the pulmonary blood flow in the Fontan circulation. Respiratory complications compromise efficiency in the Fontan circulation. It was also revealed that the pulmonary blood flow was mutually dammed up and sucked in by increases and decreases in atrial pressure.

Thoracoscopic plication for diaphragmatic eventration after surgery for congenital heart disease in children

OBJECTIVE

The aim of this study was to clarify the role of thoracoscopic plication for diaphragmatic eventration after surgery for congenital heart disease (CHD) in children.

PATIENTS AND METHODS

We retrospectively reviewed the medical charts of pediatric patients who had undergone thoracoscopic plication of diaphragmatic eventration after surgery for CHD between 2008 and 2013 at our department.

RESULTS

Five patients were identified during the study period. The median age and body weight of the patients were 7.6 months and 6.6 kg, respectively. The associated CHDs were pulmonary artery atresia in 3 patients, truncus arteriosus in 1 patient, and double-outlet right ventricle in 1 patient. Four patients needed preoperative mechanical respiratory support. At operation, all the patients received CO2 insufflation (4 mm Hg), and single-lung ventilation was attempted in 3 patients using a bronchial blocker. A sufficient operative field was maintained by CO2 insufflation in all the patients regardless of single-lung ventilation. The procedure was not converted to open operation in any patient. Postoperative extubation was performed in the operating room in 1 patient, on the day of operation in 2 patients, and on postoperative Days 1 and 2 in 2 patients. Air embolism was not observed in any of the patients. Diaphragmatic eventration did not recur in any of the patients after thoracoscopic plication.

CONCLUSIONS

Thoracoscopic plication is a safe and effective procedure for pediatric diaphragmatic eventration after surgery for CHD. Considering the sufficient operative field maintained by CO2 insufflation, single-lung ventilation using a bronchial blocker would be unnecessary for this procedure. With its safety and good outcome, early thoracoscopic plication is a good treatment option for pediatric patients with symptomatic diaphragmatic eventration after surgery for CHD.

Aggressive coil embolization for connected aortopulmonary collateral arteries with large shunts developed after diaphragmatic plication performed after cavopulmonary connection to facilitate Fontan circulation

We present two patients of univentricular physiology, who underwent diaphragmatic plication following the complication of diaphragmatic paralysis resulting from a bidirectional Glenn procedure. Over several months, complex connections developed between aortopulmonary collateral arteries, resulting in large shunts around the plication sites and an increased central pulmonary artery (PA) pressure to 14-15 mmHg. Most blood flow from these connections was reversed in the lower PAs of the affected side, reaching the contralateral lungs through the central PAs. Selective angiography identified almost all of the feeding arteries and complex connections. Aggressive coil embolization at these sites decreased the PA pressure to approximately 10 mmHg, enabling the Fontan procedure.

Diaphragmatic palsy after cardiac surgical procedures in patients with congenital heart

Paralysis of diaphragm on one or, exceptionally, both sides is a common cause of delayed recovery and excessive morbidity following pediatric cardiac surgery. The consequences of this complication after all forms of congenital heart surgery in newborns and young infants can be potentially serious. The impact of diaphragmatic palsy on the physiology after single ventricle palliations is particularly significant. It is necessary for all professionals taking care of children with heart disease to be familiar with the etiology, diagnosis, and management of this condition. Early recognition and prompt management of diaphragmatic palsy can potentially reduce the duration of mechanical ventilation and intensive care in those who develop this complication. This review summarizes the anatomy of the phrenic nerves, reasons behind the occurrence of diaphragmatic palsy, and suggests practical guidelines for management.

In situ pericardial extracardiac lateral tunnel Fontan operation: fifteen-year experience

BACKGROUND

The study purpose is to evaluate the long-term outcome of the in situ pericardial extracardiac lateral tunnel Fontan operation.

METHODS

From June 1994 to August 2009, 160 patients with single ventricle (boys, n = 96, 60%, median age = 39 months, mean weight 15.5 kg) underwent the pedicled pericardial extracardiac lateral tunnel operation. Patients' charts were reviewed for perioperative and long-term follow-up data, outcome, and mortality. The potential growth of these tunnels was evaluated.

RESULTS

The main diagnoses included tricuspid atresia (n = 44, 27%); double-outlet right ventricle (n = 29, 18%), and hypoplastic left heart syndrome (n = 26, 16%). The mean follow-up was 6.5 ± 3.7 years (range: 0.1-15 years). There were 2 (1.3%) operative and 6 (3.7%) late deaths. Actuarial survival at 14 years was 93%. Early complications included prolonged effusions (n = 35, 22%), chylothorax (n = 5, 3.1%), readmissions (n = 35, 22%), cerebrovascular accidents (n = 8, 5%), contralateral phrenic nerve palsy (n = 1, 0.8%), and transient arrhythmias (n = 5, 3.1%). No pacemaker was needed. Late complications included tunnel stenosis (n = 3, 1.8%) managed with balloon dilatation and stenting in 2 patients and surgical revision in 1; tunnel thrombosis (n = 2, 1.2%) causing death in both patients; and protein losing-enteropathy (n = 4, 2.5%). Follow-up echocardiography of 10 patients showed laminar flow, no turbulence/gradient at the inferior vena cava and mid-tunnel levels. The diameter indexed to body surface area showed growth, reduction, or no change depending on flow demands.

CONCLUSIONS

The construction of the extracardiac lateral tunnel Fontan conduit using viable pedicled pericardium is a relatively simple, durable, and safe operation. Long-term follow-up confirms low morbidity and mortality. Fenestration is unnecessary in most patients. This viable tunnel adapts to physiologic flow demands.

Optimization of inflow waveform phase-difference for minimized total cavopulmonary power loss

The Fontan operation is a palliative surgical procedure performed on children, born with congenital heart defects that have yielded only a single functioning ventricle. The total cavo-pulmonary connection (TCPC) is a common variant of the Fontan procedure, where the superior vena cava (SVC) and inferior vena cava (IVC) are routed directly into the pulmonary arteries (PA). Due to the limited pumping energy available, optimized hemodynamics, in turn, minimized power loss, inside the TCPC pathway is required for the best optimal surgical outcomes. To complement ongoing efforts to optimize the anatomical geometric design of the surgical Fontan templates, here, we focused on the characterization of power loss changes due to the temporal variations in between SVC and IVC flow waveforms. An experimentally validated pulsatile computational fluid dynamics solver is used to quantify the effect of phase-shift between SVC and IVC inflow waveforms and amplitudes on internal energy dissipation. The unsteady hemodynamics of two standard idealized TCPC geometries are presented, incorporating patient-specific real-time PC-MRI flow waveforms of "functional" Fontan patients. The effects of respiration and pulsatility on the internal energy dissipation of the TCPC pathway are analyzed. Optimization of phase-shift between caval flows is shown to lead to lower energy dissipation up to 30% in these idealized models. For physiological patient-specific caval waveforms, the power loss is reduced significantly (up to 11%) by the optimization of all three major harmonics at the same mean pathway flow (3 L/min). Thus, the hemodynamic efficiency of single ventricle circuits is influenced strongly by the caval flow waveform quality, which is regulated through respiratory dependent physiological pathways. The proposed patient-specific waveform optimization protocol may potentially inspire new therapeutic applications to aid postoperative hemodynamics and improve the well being of the Fontan patients.

Subdiaphragmatic venous hemodynamics in patients with biventricular and Fontan circulation after diaphragm plication

OBJECTIVE

Diaphragm paralysis owing to phrenic nerve injury can result in significant morbidity in children undergoing surgical management of congenital cardiac defects. Diaphragm plication is the accepted therapy for diaphragm paralysis. We have investigated subdiaphragmatic venous hemodynamics in patients with biventricular and Fontan circulation after diaphragm plication.

METHODS

Doppler ultrasound was used to evaluate flows in the hepatic vein, portal vein, and subhepatic inferior vena cava under respiratory monitoring and with a tilt table. Twenty-nine patients with biventricular circulation were studied: 19 with normal diaphragms and 10 after diaphragm plication. Twenty-eight patients with total cavopulmonary connections after the Fontan procedure were also studied: 19 with normal diaphragms and 9 with plicated diaphragms. Inspiratory/expiratory flow ratios in supine and upright positions were calculated to investigate respiratory effects, and upright/supine flow ratios were calculated to assess gravity effects.

RESULTS

In patients with biventricular circulation and normal diaphragms, hepatic venous flow was augmented by inspiration; this effect was reduced in patients with a plicated diaphragm (upright inspiratory/expiratory flow ratios: 2.4 vs 1.4, respectively; P = .01). Portal venous flow was higher during expiration; this effect was lost in patients with a plicated diaphragm (supine inspiratory/expiratory flow ratios: 0.8 and 1.0; P < .05). In Fontan patients with normal diaphragms, hepatic venous flow depended heavily on inspiration. This effect was blunted in patients with a plicated diaphragm (supine inspiratory/expiratory flow ratios: 3.2 vs 2.3; P < .05). Expiratory augmentation of portal flow was absent in Fontan patients with normal diaphragms and reversed in patients a plicated diaphragm (supine inspiratory/expiratory flow ratios: 1.0 vs 1.6; P = .02). Gravity reduced Fontan portal venous flow; having a plicated diaphragm did not alter this effect (upright/supine flow ratios: 0.7 vs 0.7).

CONCLUSIONS

In patients with biventricular and those with Fontan circulation with a paralyzed diaphragm, plication does not completely restore normal subdiaphragmatic venous hemodynamics. In Fontan patients with a plicated diaphragm, important inspiration-derived hepatic venous flow is suppressed, and portal venous flow loses its normal expiratory augmentation. These flow dynamics share similarities with those observed in patients with failing Fontan circulation. This suboptimal splanchnic circulation may contribute to early problems of prolonged pleural effusions and ascites and potentially may promote late Fontan failure. Phrenic nerve injury should consequently be avoided at all costs before or at the time of the Fontan operation.

Mid-term follow-up in patients with diaphragmatic plication after surgery for congenital heart disease

OBJECTIVE

Diaphragmatic palsy (DP) is a rare but severe complication after surgery for congenital heart disease. Transthoracic diaphragmatic plication is an effective means of treatment for those with respiratory impairment due to DP, but little is known about the mid-term effects of diaphragmatic plication.

DESIGN

We performed a study in 24 patients with history of DP. Diaphragm movement was assessed using ultrasound. Patients with DP who were old enough were additionally followed-up with lung function and exercise testing. A group of patients with similar age, diagnoses and operations served as controls.

RESULTS

Ultrasound showed that in the majority of cases with history of DP the paralysed diaphragm was static, independently of whether it was plicated or not. Patients with DP had a more restrictive lung function pattern (VC: 54.3 vs. 76.4% predicted, p<0.001; FEV(1): 58.4 vs. 86.2% predicted, p<0.001) and a lower exercise capacity compared with the control group (peak VO2: 24.5 vs. 31.3 ml/kg/min, p=0.03). Comparing patients with and without plication for DP, only a tendency towards lower lung function values in patients after diaphragmatic plication, but no differences regarding exercise capacity, could be found.

CONCLUSIONS

Our results provide evidence that DP is a serious surgical complication with a reduction in lung function and exercise capacity, even at mid-term follow-up; however, diaphragmatic plication, a useful tool in treating post-surgical DP in children with respiratory impairment, seems to be without mid-term risk in terms of recovery of phrenic nerve function, lung function values, and exercise capacity.

Seven-year clinical experience with the extracardiac pedicled pericardial Fontan operation

BACKGROUND

Although improved perioperative outcomes with growth potential of the extracardiac pedicled pericardial Fontan (EPPF) operation have been suggested, no advantage has been demonstrated.

METHODS

We retrospectively reviewed our institutional experience of 54 consecutive patients undergoing EPPF between June 1996 and August 2003. Clinical and echocardiographic follow-up was obtained yearly with a mean follow-up of 2.8 +/- 2.0 years.

RESULTS

There were 29 males, median age 3.3 years (2-6.8). Median cardiopulmonary bypass time was 79 min (39-295). Fibrillatory arrest was used briefly in 9 patients, of which 6 were for fenestration. One Fontan required takedown (1.8%) and there was 1 death (1.8%) from Candida mediastinitis. Median intensive care unit stay, hospital length of stay, and chest tube drainage were 4 days, 12 days, and 8 days, respectively. Arrhythmias occurred in 7 patients. Three (5.6%) of these had preexisting Holter abnormalities requiring permanent pacemaker implantation. Freedom from thromboembolic events, reoperation, and death at 2.8 years after discharge were 96.2%, 98.1%, and 100%, respectively. All patients were New York Heart Association class I-II, with median oxygen saturation of 94 %. Only 5 patients (9.4%) had mild self-restricted activities. Echocardiographic evaluation revealed excellent ventricular function and flow dynamics.

CONCLUSIONS

At midterm follow-up this technique yields outcomes as good as the other Fontan techniques and with further follow-up may prove to be superior. However, at this point no clear advantage has been demonstrated. The low rate of complications and potential for growth are appealing features of this procedure.

Postoperative phrenic nerve palsy: early clinical implications and management

OBJECTIVE

We examined the clinical impact of diaphragmatic palsy (DP) as a result of phrenic nerve injury following cardiothoracic surgery, specifically its effects on morbidity and mortality, early regeneration capacity of the phrenic nerve, and role of surgical diaphragmatic plication.

METHODS

A retrospective case control study was performed in 74 children with DP and 74 matched controls after cardiothoracic surgery within the past 14 years.

RESULTS

Following 5,128 surgical procedures in children (aged under 18 years) we found an incidence of DP of 1.4%. There were no differences in mortality between the groups, and the cause of death was not related to DP or plication in any of the patients. However, patients with diaphragm impairment had significantly longer duration of mechanical ventilation (median 3 days vs. 1), ICU stay (7 days vs. 3.5), duration of hospital stay (16 days vs. 12), and for antibiotic treatment (16 days vs. 7). Because of prolonged respiratory problems 40 children (54%) underwent surgical diaphragmatic plication to flatten the diaphragm in its inspiratory position. In children with DP younger age was a strong predictor for plication (median 3.8 months vs. 12.1).

CONCLUSIONS

Especially in newborns and young infants with DP the length of mechanical ventilation, ICU stay, and hospital stay are prolonged. Early spontaneous recovery of the phrenic nerve is rare. In cases of respiratory impairment early transthoracic diaphragmatic plication is an effective means of treatment.

Outcomes after the Fontan procedure

Over the past two decades, advances in congenital heart surgery, pediatric cardiology, and intensive care medicine have dramatically increased the survival of infants with critical congenital heart disease. The group of patients that has perhaps benefited the most from this progress has been the single-ventricle population. Staged palliation culminating in the Fontan procedure has resulted in a decreasing mortality rate and an increase in the number of single-ventricle survivors. Over the past 18 months, many studies have focused on outcomes after the Fontan procedure. These reports demonstrate progressive improvement in early postoperative survival and intermediate and late postoperative outcomes due to surgical innovations, such as the lateral tunnel and extracardiac Fontan modifications, and fenestration, as well as technological improvements, such as modified ultrafiltration. Despite these improvements, significant morbidity remains after the Fontan completion, including myocardial systolic and diastolic dysfunction, systemic arterial and venous hemodynamic abnormalities, diminished exercise capacity, arrhythmias, protein-losing enteropathy, somatic growth retardation, neo-aortic valve root dilation and insufficiency, thromboembolic complications, and below-average cognitive development.