Presented is a retrospective outcome study of a 15-year single institutional experience with a contemporary cohort of patients with hypoplastic left heart syndrome and complex that underwent a “Giessen Hybrid” stage I as initial palliation. Hybrid approach consisting of surgical bilateral pulmonary artery banding and percutaneous duct stenting with or without atrial septum manipulation was developed from a rescue approach to a first-line procedure. Comprehensive Aristotle score defined pre-operative condition. Fifteen-year follow-up mortality is reported as occurring within the staged univentricular palliation or before and after biventricular repair. Hybrid stage I was performed in 154 patients; 107 should be treated by single ventricle palliation, 33 by biventricular repair (BVR), 7 received heart transplantation, and 7 were treated by comfort care, respectively. Overall 34 children died. The Aristotle score (mean value 18.2 ± 3) classified for univentricular circulations in newborns did not have statistical impact on the outcome. Two patients died during stage I (1.2 %), and the interstage I mortality was 6.7 %, and stage II mortality 9 %, respectively. Stage III was up to now performed in 57 patients without mortality. At 1 year, the overall unadjusted survival of HLHS and variants was 84 % and following BVR 89 %, respectively. The Fifteen-year survival rate for HLHS and variants was 77 %, with no significant impact of birth weight of less than 2.5 kg. In conclusion, Hybrid stage I fulfilled the criteria of life-saving approach. In our institution, Hybrid procedure replaced Norwood-staged palliation with a considerable mid- and long-term survival rate. Considering interstage mortality close surveillance is mandatory.
Hypoplastic left heart syndrome; Hypoplastic left heart complex; Hybrid approach
For hypoplastic left heart syndrome (HLHS), there have been concerns regarding pulmonary artery growth and ventricular dysfunction after first stage surgery consisting of the Norwood procedure modified with a right ventricle-to-pulmonary artery conduit. We report our experience using cardiovascular magnetic resonance (CMR) to determine and follow pulmonary arterial growth and ventricular function in this cohort.
Following first stage palliation, serial CMR was performed at 1 and 10 weeks post-operatively, followed by cardiac catheterization at 4 – 6 months. Thirty-four of 47 consecutive patients with HLHS (or its variations) underwent first stage palliation. Serial CMR was performed in 20 patients. Between studies, ejection fraction decreased (58 ± 9% vs. 50 ± 5%, p < 0.05). Pulmonary artery growth occurred on the left (6 ± 1 mm vs. 4 ± 1 mm at baseline, p < 0.05) but not significantly in the right. This trend continued to cardiac catheterization 4–6 months post surgery, with the left pulmonary artery of greater size than the right (8.8 ± 2.2 mm vs. 6.7 +/- 1.9 mm, p < 0.05). By CMR, 5 had pulmonary artery stenoses initially, and at 2 months, 9 had stenoses. Three of the 9 underwent percutaneous intervention prior to the second stage procedure.
In this cohort, reasonable growth of pulmonary arteries occurred following first stage palliation with this modification, although that growth was preferential to the left. Serial studies demonstrate worsening of ventricular function for the cohort. CMR was instrumental for detecting pulmonary artery stenosis and right ventricular dysfunction.
OBJECTIVE--To assess the feasibility of pulmonary artery banding, atrial septectomy or septostomy, and percutaneous stenting of the arterial duct in babies with the hypoplastic left heart syndrome. PATIENTS--Four infants with hypoplastic left heart syndrome. SETTING--Two supraregional paediatric cardiac centres. METHODS--Ductal patency was maintained initially with prostaglandin E. Banding of the proximal branch pulmonary arteries was performed through a median sternotomy and open atrial septectomy was performed if balloon septostomy was not. Stainless steel stents (Johnson & Johnson) mounted in a balloon catheter were implanted into the arterial duct under radiographic control and expanded to a diameter of approximately 8 mm, prostaglandin treatment was then stopped. RESULTS--All the patients survived the immediate postoperative period and maintenance of wide ductal patency was achieved in three of the four patients by stent implantation. Two weeks after the procedure two babies died of right ventricular failure and respiratory infection: some distal ductal constriction had occurred in one where the stent was not quite sufficiently distally placed. One child was discharged home 15 days after treatment and was well at follow up at age 16 weeks and one was stable but required diuretic therapy five weeks after the procedure. CONCLUSIONS--This new approach is technically feasible. At least in the short term it seems to offer hope of effective palliation for the hypoplastic left heart syndrome and it warrants further study.
The initial palliative procedure for patients born with hypoplastic left heart syndrome and related single right ventricle anomalies, the Norwood procedure, remains among the highest risk procedures in congenital heart surgery. The classic Norwood procedure provides pulmonary blood flow with a modified Blalock–Taussig shunt. Improved outcomes have been reported in a few small, nonrandomized studies of a modification of the Norwood procedure that uses a right ventricle–pulmonary artery shunt to provide pulmonary blood flow. Other nonrandomized studies have shown no differences between the two techniques.
The Pediatric Heart Network designed a randomized clinical trial to compare outcomes for subjects undergoing a Norwood procedure with either the right ventricle–pulmonary artery or modified Blalock–Taussig shunt. Infants with a diagnosis of single, morphologically right ventricle anomaly who are undergoing a Norwood procedure are eligible for inclusion in this study. The primary outcome is death or cardiac transplant 12 months after random assignment. Secondary outcomes include postoperative morbidity after Norwood and stage II palliation procedures, right ventricular function and pulmonary arterial growth at stage II palliation, and neurodevelopmental outcomes at 14 months old. Incidence of adverse events will also be compared between treatment groups.
This study will make an important contribution to the care of patients with hypoplastic left heart syndrome and related forms of single, morphologically right ventricle. It also establishes a model with which other operative interventions for patients with congenital cardiovascular malformations can be evaluated in the future.
Objective: To present an institutional experience with stent placement in the arterial duct combined with bilateral banding of the pulmonary artery branches as a basis for various surgical strategies in newborns with hypoplastic left heart obstructive lesions.
Design: Observational study.
Setting: Paediatric heart centre in a university hospital.
Patients: 20 newborns with various forms of left heart obstructive lesions and duct dependent systemic blood flow.
Interventions: Patients underwent percutaneous ductal stenting and surgical bilateral pulmonary artery banding. Atrial septotomy by balloon dilatation was performed as required, in one premature baby by the transhepatic approach.
Main outcome measures: Survival; numbers of and reasons for palliative and corrective cardiac surgery.
Results: One patient died immediately after percutaneous ductal stenting. One patient died in connection with the surgical approach of bilateral pulmonary banding. Stent and ductal patency were achieved for up to 331 days. Two patients underwent heart transplantation and two patients died on the waiting list. Ten patients had a palliative one stage procedure with reconstruction of the aortic arch and bidirectional cavopulmonary connection at the age of 3.5–6 months. There was one death. One patient is still awaiting this approach. Two patients received biventricular repair. In one, biventricular repair will soon be provided.
Conclusions: Stenting the arterial duct combined with bilateral pulmonary artery banding in newborns with hypoplastic left heart or multiple left heart obstructive lesions allows a broad variation of surgical strategies depending on morphological findings, postnatal clinical conditions, and potential ventricular growth.
ductus arteriosus; stent; Norwood repair; hypoplastic left heart
This study sought to investigate changes in magnetic resonance imaging (MRI) ventricular volumes and vascular dimensions before hemi-Fontan (HF) and before total cavopulmonary connection (TCPC) in children with hypoplastic left heart syndrome (HLHS).
The systemic right ventricle (RV) in HLHS is subject to significant changes in volume loading throughout the surgical stages of palliation, particularly after the HF.
Fifty-eight patients had paired pre-HF and pre-TCPC MRI for assessment of changes of RV volumes, neoaortic flow, and vascular dimensions.
Comparison of pre-HF and pre-TCPC MRI results showed a decrease of indexed RV end-diastolic volume and end-systolic volume (98 ml/m2 to 87 ml/m2 and 50 ml/m2 to 36 ml/m2, respectively) with stroke volume remaining constant (49 ml/m2 vs. 51 ml/m2), leading to an increased RV ejection fraction (51% vs. 59%). These findings persisted after excluding the 3 patients who underwent tricuspid valve repair as part of their HF procedure. Indexed RV end-diastolic volume plotted against neoaortic stroke volume demonstrated a Frank-Starling–like curve that shifted upward after HF. The indexed distal left and right cross-sectional pulmonary artery areas were reduced after HF.
In HLHS, serial MRI shows the adaptation of the systemic RV after HF with volume reduction in the context of a preserved stroke volume and an increased ejection fraction. The staged palliation in HLHS may be a risk factor particularly for reduced left pulmonary artery growth in itself as no factors investigated in this study were found to significantly impact on this.
hemi-Fontan operation; hypoplastic left heart syndrome; magnetic resonance imaging; Norwood procedure; remodeling of systemic right ventricle; 3D, 3-dimensional; EDV, end-diastolic volume; EF, ejection fraction; ESV, end-systolic volume; HF, hemi-Fontan; HLHS, hypoplastic left heart syndrome; HR, heart rate; iEDV, indexed end-diastolic volume; iESV, indexed end-systolic volume; iSV, indexed stroke volume; LPA, left pulmonary artery; LV, left ventricle; MRI, magnetic resonance imaging; RPA, right pulmonary artery; RV, right ventricle; SENSE, sensitivity encoding; SSFP, steady-state free precession; TCPC, total cavopulmonary connection; TR, tricuspid regurgitation
Cardio-pulmonary interactions play an important role in the pathophysiology of hypoplastic left heart syndrome (HLHS). Pulmonary vasculopathy has been identified, especially in those with restrictive/intact atrial septum (R/IAS). Responsiveness of the pulmonary vasculature to maternal hyperoxygenation (MH) may provide a tool to assess the degree of pulmonary vasculopathy present prior to birth.
Methods and Results
Doppler echocardiography was performed in 27 normal and 43 HLHS fetuses. In HLHS, sampling was repeated after 10 minutes of MH with 60% FiO2, and after 5 minutes of recovery. Sampling was performed in the proximal, mid-portion, and distal branch pulmonary artery (PA). Pulsatility index (PI) was used as a measure of vascular impedance. Of the HLHS fetuses, 34 had an open inter-atrial septum and 9 had a R/IAS. At birth, 5 fetuses underwent immediate intervention on the inter-atrial septum. Middle cerebral artery PI was lower in HLHS vs. normals (p<0.001). There was no difference in umbilical artery, ductus arteriosus, or branch PA PI between normals and HLHS. MH led to a significant decrease in PI at each of the PA sites sampled in fetuses with an open atrial septum (p<0.001); however, there no was significant change in the PI in fetuses that required immediate intervention on the atrial septum at birth. Using a cutoff value of <10% vasoreactivity, the sensitivity of MH testing for determining need for immediate intervention at birth is 100% [0.46-1.0], specificity 94% [0.78-.99], positive predictive value 71% [0.30-0.95], and negative predictive value 100% [0.86-1.0]. No untoward effects were seen with MH.
PA vasoreactivity to MH occurs in the fetus with HLHS. MH testing accurately identifies fetuses requiring urgent postnatal intervention at birth and may be used to select candidates for fetal atrial septoplasty.
congenital heart defects; fetal echocardiography; oxygen; hypoplastic left heart syndrome
In the last decade the hybrid procedure has emerged as an alternative stage I palliation in neonates with hypoplastic left heart syndrome (HLHS). This review discusses the historical aspect, surgical and interventional techniques, current outcomes and future direction of this procedure. Hybrid palliation yields equivalent but not superior stage I palliation survival and comparable 1-year survival to conventional Norwood palliation, comparable prestage II hemodynamics and pulmonary artery growth, and preserved ventricular function in stage II palliation. Hybrid palliation utilizes significantly less resource and shortens postoperative recovery. In comprehensive stage II palliation the impact of pulmonary artery reconstruction on subsequent pulmonary artery growth has not been determined and should be further investigated. A prospective, randomized trial is warranted to compare these two surgical strategies for neonates with hypoplastic left heart syndrome.
Hypoplastic left heart syndrome; Stents; Heart defects; Congenital
Objective: To quantify non-invasively right ventricular (RV) performance in infants after stage 1 palliation for hypoplastic left heart syndrome (HLHS).
Design: Prospective, observational study with two dimensional and strain Doppler echocardiography.
Setting: Single tertiary paediatric cardiology centre.
Patients: Convenience sample of nine consecutive infants with HLHS. Four whose surgery involved a systemic to pulmonary artery (S-PA) shunt were compared with five whose surgery incorporated a right ventricle to pulmonary artery (RV-PA) conduit.
Methods: Basal RV free wall longitudinal strain rate, systolic strain (ε), and RV percentage area change were calculated during a single assessment between 27–50 days after surgery.
Results: Cardiopulmonary bypass time was longer in patients who underwent RV-PA (226 (30) minutes v 181 (18) minutes, p = 0.03), but cross clamp time, duration of ventilation, and inotrope use did not differ. Two patients in the S-PA group died, on days 29 and 60 after surgery. Peak systolic strain rate (−1.24 (0.19)/s v −0.91 (0.21)/s, p = 0.048), peak ε (−17.8 (1.8)% v –13.4 (2.0)%, p = 0.01), and RV percentage area change (56 (6)% v 25 (6)%, p < 0.01) were all greater among RV-PA patients. These indices also tended to be greater in survivors as a group. Ventricular loading conditions (oxygen saturations, diuretic treatment, and blood pressure) were similar in both groups.
Conclusion: Strain Doppler echocardiography shows improved RV longitudinal systolic contractility in patients during convalescence after the RV-PA modification of stage 1 palliation for HLHS compared with those with an S-PA shunt.
strain Doppler echocardiography; hypoplastic left heart syndrome; ventricular function
Outcomes of patients undergoing cavopulmonary palliation for single ventricle physiology may be impacted by living at altitude, as the passive pulmonary circulation is dependent on the resistance of the pulmonary vascular bed. The objective of this study is to identify risk factors for failure of cavopulmonary palliation at elevated altitude.
Methods and Results
Between January 1995 and March 2007, 122 consecutive patients living at a mean altitude of 1600 m (range 305 to 2570) underwent a bidirectional Glenn (BDG). There was one in-hospital mortality and 7 late deaths. 52 have proceeded to the Fontan procedure. Survival after BDG was 92.4% at 5 years. Freedom from palliation failure, defined as death, transplant, BDG/Fontan takedown, or revision was 81% at 5 years. At a mean follow-up of 39.8 months, 90 patients (75%) were in New York Heart Association class I. Patients with failing cavopulmonary circulation had higher pre-BDG pulmonary artery pressure (PAP) (18.3±6.1 mm Hg versus 14.8±5.1 mm Hg, P=0.016) and higher pre-BDG transpulmonary gradient (TPG) (11.2±6.2 mm Hg versus 7.7±4.3 mm Hg, P=0.014). Post-BDG, patients with palliation failure had increased PAP (15.0±5.7 mm Hg versus 10.8±2.8 mm Hg, P=0.008) and indexed pulmonary vascular resistance (PVRI) (2.43±1.0 Wood U · m2 versus 1.52±0.9 Wood U · m2, P=0.007).
The majority of patients at moderate altitude have favorable outcomes after BDG or Fontan palliation. Risk factors for palliation failure at elevated altitude include PAP >15 mm Hg, TPG >8 mm Hg, and PVRI >2.5 Wood U · m2.
Fontan procedure; single ventricle; altitude
Surgical closure of patent ductus arteriosus (PDA) with severe pulmonary arterial hypertension in adults carries higher risk than in children.
To investigate the application of self‐expandable occluders for transcatheter closure of PDA associated with severe pulmonary arterial hypertension in adults, and the assessment of immediate and short‐term results.
29 adult patients (6 men, 23 women) underwent attempted transcatheter closure of PDA at a mean (standard deviation (SD)) age of 31.1 (11.4) years (range 18–58 years) and a mean (SD) weight of 54.1 (7.1) kg (range 42–71 kg). On the basis of haemodynamic and clinical data obtained before and after trial occlusion, the final duct occlusion was determined and carried out. Radiographs of the chest, electrocardiograms and echocardiograms were used for follow‐up evaluation of the treatment within 1 day, 1 month and 3–6 months after successful closure.
20 of the 29 patients had successful occlusion (group 1), and 9 patients failed (named group 2). In group 1, in which occlusion was successful, mean (SD) pulmonary arterial pressures decreased markedly after trial occlusion: 78 (19.3) mm Hg (range 50–125 mm Hg) before occlusion and 41 (13.8) mm Hg (range 23–77 mm Hg) after occlusion. Systemic arterial oxygen saturation was found to be >90% in 19 patients and <90% in the remaining patient before inhalation of oxygen, and >95% during inhalation of oxygen or after occlusion in all 20 patients. In group 2, the occlusion was not successful, because in two patients the device was not available; another two patients showed worsening of symptoms. The other five patients showed increased pulmonary arterial pressures after trial closure; their mean (SD) pulmonary arterial pressures increased by 10.3 (6) mm Hg (4–16 mm Hg) after trial occlusion, and systemic arterial oxygen saturation was 85.5% (2.6%) (range 82.6–88%) before inhalation of oxygen and 94.7% (1.7%) (range 90.7–99.1%) during inhalation of oxygen. In group 1, the dimensions of the left atrium, left ventricle and pulmonary artery increased considerably in 3–6‐months of follow‐up compared with those of preocclusion.
Transcatheter closure is an effective treatment for adults with PDA associated with reversible severe pulmonary arterial hypertension. Further research is needed for the evaluation of long‐term results.
The presence of a pulmonary artery aneurysm, major aortopulmonary and coronary–pulmonary collateral vessels, and severe pulmonary hypertension in an adult with unilateral pulmonary artery agenesis and previous patent ductus arteriosus ligation is very rare. A 34-year-old man experienced these conditions. When he was 10 years old, catheterization and angiography revealed right pulmonary artery agenesis, dilation of the main pulmonary artery, multiple collateral vessels extending from the aorta to the right pulmonary system, and a patent ductus arteriosus (shunt ratio, 3.57) that was then ligated; the other conditions were not corrected.
This adult patient was in New York Heart Association functional class II; mild central cyanosis was detected only during exercise. The right pulmonary arterial system was seen only at the right hilar area via collateral vessels from the subclavian, bronchial, internal mammary, and intercostal arteries. Angiography revealed collateral vessels from the right and circumflex coronary arteries to the right pulmonary system. The right intraparenchymal pulmonary arterial systems were patent but of small diameter (pulmonary artery pressure, 85 mmHg; ratio of peak right-to-left ventricular pressure, 0.94; peak pulmonary pressure unresponsive to 100% oxygen). Pulmonary vascular resistance was not estimated because of the risk of aneurysmal rupture.
We concluded that irreversible pulmonary hypertension had developed (delayed by the patent ductus arteriosus ligation in childhood) and that the patient's only chance for survival was heart-lung transplantation. To sustain the patient until surgery, we administered sildenafil. Herein, we describe the vascular conditions that accompany unilateral absence of the pulmonary artery, and therapeutic methods.
Adult; cardiovascular abnormalities; collateral circulation/physiology; coronary vessel anomalies/complications/diagnosis/physiopathology; diagnosis, differential; heart defects, congenital; hypertension, pulmonary/diagnosis/drug therapy/etiology; pulmonary artery/abnormalities/anatomy & histology/physiopathology; sildenafil; vasodilator agents/therapeutic use
Hypoplastic left heart syndrome(HLHS) refers to the abnormal development of the left-sided cardiac structures, resulting in obstruction to blood flow from the left ventricular outflow tract. In addition, the syndrome includes underdevelopment of the left ventricle, aorta, and aortic arch, as well as mitral atresia or stenosis. HLHS has been reported to occur in approximately 0.016 to 0.036% of all live births. Newborn infants with the condition generally are born at full term and initially appear healthy. As the arterial duct closes, the systemic perfusion becomes decreased, resulting in hypoxemia, acidosis, and shock. Usually, no heart murmur, or a non-specific heart murmur, may be detected. The second heart sound is loud and single because of aortic atresia. Often the liver is enlarged secondary to congestive heart failure. The embryologic cause of the disease, as in the case of most congenital cardiac defects, is not fully known. The most useful diagnostic modality is the echocardiogram. The syndrome can be diagnosed by fetal echocardiography between 18 and 22 weeks of gestation. Differential diagnosis includes other left-sided obstructive lesions where the systemic circulation is dependent on ductal flow (critical aortic stenosis, coarctation of the aorta, interrupted aortic arch). Children with the syndrome require surgery as neonates, as they have duct-dependent systemic circulation. Currently, there are two major modalities, primary cardiac transplantation or a series of staged functionally univentricular palliations. The treatment chosen is dependent on the preference of the institution, its experience, and also preference. Although survival following initial surgical intervention has improved significantly over the last 20 years, significant mortality and morbidity are present for both surgical strategies. As a result pediatric cardiologists continue to be challenged by discussions with families regarding initial decision relative to treatment, and long-term prognosis as information on long-term survival and quality of life for those born with the syndrome is limited.
Double-outlet right ventricle (DORV) with a restrictive ventricular septum is a rare but highly morbid phenomenon that can be complicated by progressive left ventricular hypertrophy, arrhythmias, aneurysm formation, severe pulmonary hypertension, and death in the newborn. Surgical creation or enlargement of a ventricular septal defect (VSD) is palliative but may damage the conduction system or the atrioventricular valves in the newborn. This report presents a transcatheter approach to palliation for a newborn that had DORV with a restrictive ventricular septum.
A full-term infant girl (2.9 kg) referred for hypoxia (80 % with room air) and murmur was found to have DORV, interrupted inferior vena cava, and restrictive VSD (95-mmHg gradient). Transhepatic access was performed, and an internal mammary (IM) catheter was advanced through the atrial septal defect and into the left ventricle. By transesophageal echocardiographic guidance, a Baylis radiofrequency perforation wire was used to cross the ventricular septum, and the defect was enlarged using a 4-mm cutting balloon. A bare metal stent then was deployed to maintain the newly created VSD. The patient did well after the procedure but required pulmonary artery banding 4 days later. She returned 5 months later with cyanosis and the development of obstructing right ventricle muscle bundles, requiring further surgical palliation.
This report describes the first transcatheter creation of VSD in DORV with a restrictive ventricular septum in a newborn infant. Use of the radiofrequency catheter in combination with cutting balloon dilation and stent implantation is an efficient method for creating a VSD in such a patient.
Electronic supplementary material
The online version of this article (doi:10.1007/s00246-012-0337-1) contains supplementary material, which is available to authorized users.
Restrictive VSD; Transcatheter VSD creation; VSD stenting
Patent arterial duct (PAD) is a congenital heart abnormality defined as persistent patency in term infants older than three months. Isolated PAD is found in around 1 in 2000 full term infants. A higher prevalence is found in preterm infants, especially those with low birth weight. The female to male ratio is 2:1. Most patients are asymptomatic when the duct is small. With a moderate-to-large duct, a characteristic continuous heart murmur (loudest in the left upper chest or infraclavicular area) is typical. The precordium may be hyperactive and peripheral pulses are bounding with a wide pulse pressure. Tachycardia, exertional dyspnoea, laboured breathing, fatigue or poor growth are common. Large shunts may lead to failure to thrive, recurrent infection of the upper respiratory tract and congestive heart failure. In the majority of cases of PAD there is no identifiable cause. Persistence of the duct is associated with chromosomal aberrations, asphyxia at birth, birth at high altitude and congenital rubella. Occasional cases are associated with specific genetic defects (trisomy 21 and 18, and the Rubinstein-Taybi and CHARGE syndromes). Familial occurrence of PAD is uncommon and the usual mechanism of inheritance is considered to be polygenic with a recurrence risk of 3%. Rare families with isolated PAD have been described in which the mode of inheritance appears to be dominant or recessive. Familial incidence of PAD has also been linked to Char syndrome, familial thoracic aortic aneurysm/dissection associated with patent arterial duct, and familial patent arterial duct and bicuspid aortic valve associated with hand abnormalities. Diagnosis is based on clinical examination and confirmed with transthoracic echocardiography. Assessment of ductal blood flow can be made using colour flow mapping and pulsed wave Doppler. Antenatal diagnosis is not possible, as PAD is a normal structure during antenatal life. Conditions with signs and symptoms of pulmonary overcirculation secondary to a left-to-right shunt must be excluded. Coronary, systemic and pulmonary arteriovenous fistula, peripheral pulmonary stenosis and ventricular septal defect with aortic regurgitation and collateral vessels must be differentiated from PAD on echocardiogram. In preterm infants with symptomatic heart failure secondary to PAD, treatment may be achieved by surgical ligation or with medical therapy blocking prostaglandin synthesis (indomethacin or ibuprofen). Transcatheter closure of the duct is usually indicated in older children. PAD in preterm and low birth weight infants is associated with significant co-morbidity and mortality due to haemodynamic instability. Asymptomatic patients with a small duct have a normal vital prognosis but have a lifetime risk of endocarditis. Patients with moderate-to-large ducts with significant haemodynamic alterations may develop irreversible changes to pulmonary vascularity and pulmonary hypertension.
Simplified Aortic Cannulation (SAC), wherein the innominate artery is used as the arterial inflow site rather than the ascending aorta, has proved to be a useful technique for arterial cannulation especially for small neonates undergoing complex cardiac operations. Since few technical options are available for re-entry cardiac injuries in small infants, we postulate that this technique may be equally helpful in those situations.
We employed SAC in 4 infants undergoing reoperative cardiac surgery (prior Norwood, n = 2; prior arterial switch operation with suprasystemic pulmonary artery pressures after a Le Compte maneuver, n = 1; prior Ebstein's anomaly, n = 1). In all cases the innominate artery was exposed at the level of the supra-sternal notch, and a 3.5 mm expanded polytetrafluoroethylene (ePTFE) graft was anastomosed to the innominate artery (n = 3), and a 10 French cannula inserted into the graft for whole-body perfusion. Right atrial cannulation was obtained by dividing the anterior aspect of the diaphragm at the level of the xiphisternum, gaining easy access to the right atrial-inferior vena cava junction, without separating the sternal edges.
Discussion and Evaluation
All four infants successfully underwent their operations using SAC. In one case (2nd stage palliation for hypoplastic left heart syndrome) a cardiac injury occurred upon sternal reentry, but utilizing SAC, this was repaired without consequence.
Simplified aortic cannulation and direct right atrial cannulation may be obtained without dividing the sternum in complex reoperative infant surgeries, without making additional incisions. This may be life-saving in reoperative cardiac injuries in small infants.
Dexmedetomidine is a highly selective α2-adrenoceptor agonist with sedative, anxiolytic and analgesic properties that has minimal effects on respiratory drive. Its sedative and hypotensive effects are mediated via central α2A and imidazoline type 1 receptors while activation of peripheral α2B–adrenoceptors result in an increase in arterial blood pressure and systemic vascular resistance (SVR). In this randomized, prospective, clinical study we attempted to quantify the short-term hemodynamic effects resulting from a rapid IV bolus administration of dexmedetomidine in pediatric cardiac transplant patients.
Twelve patients, aged ≤10 years of age, weighing ≤40kg, presenting for routine surveillance of right and left heart cardiac catheterization after cardiac transplantation were enrolled. After an inhaled or IV induction, the tracheas were intubated and anesthesia was maintained with 1 minimum alveolar concentration of isoflurane in room air, fentanyl (1mcg/kg) and rocuronium (1mg/kg). At the completion of the planned cardiac catheterization, 100% oxygen was administered. After recording a set of baseline values that included heart rate (HR), systolic blood pressure, diastolic blood pressure, central venous pressure, systolic pulmonary artery pressure, diastolic pulmonary artery pressure, pulmonary artery wedge pressure and thermodilution-based cardiac output, a rapid IV dexmedetomidine bolus of either 0.25mcg/kg or 0.5mcg/kg was administered over 5 seconds. The hemodynamic measurements were repeated at 1 min and 5 mins.
There were 6 patients in each group. Investigation suggested that systolic blood pressure, diastolic blood pressure, systolic pulmonary artery pressure, diastolic pulmonary artery pressure, pulmonary artery wedge pressure and systemic vascular resistance all increased at 1 minute after rapid IV bolus for both doses, and decreased significantly to near baseline for both doses by 5 minutes. The transient increase in pressures was more pronounced in the systemic system than in the pulmonary system. In the systemic system there was a larger percent increase in the diastolic pressures than the systolic pressures. Cardiac output, CVP and pulmonary vascular resistance did not change significantly. HR decreased at 1 min for both doses and was, within the 0.5 mcg/kg group, the only hemodynamic variable still changed from baseline at the 5 min time point
Rapid IV bolus administration of dexmedetomidine in this small sample of children having undergone heart transplants was clinically well tolerated, although it resulted in a transient but significant increase in systemic and pulmonary pressure and a decrease in HR. In the systemic system there is a larger percent increase in the diastolic pressures than the systolic pressures, and furthermore these transient increases in pressures were more pronounced in the systemic system than in the pulmonary system.
The theoretical differences in energy losses as well as coronary flow with different band sizes for branch pulmonary arteries (PA) in hypoplastic left heart syndrome (HLHS) remain unknown. Our objective was to develop a computational fluid dynamic model (CFD) to determine the energy losses and pulmonary-to-systemic flow rates. This study was done for three different PA band sizes.
Three-dimensional computer models of the hybrid procedure were constructed using the standard commercial CFD softwares Fluent and Gambit. The computer models were controlled for bilateral PA reduction to 25% (restrictive), 50% (intermediate) and 75% (loose) of the native branch pulmonary artery diameter. Velocity and pressure data were calculated throughout the heart geometry using the finite volume numerical method. Coronary flow was measured simultaneously with each model. Wall shear stress and the ratio of pulmonary-to-systemic volume flow rates were calculated. Computer simulations were compared at fixed points utilizing echocardiographic and catheter-based metric dimensions.
Restricting the PA band to a 25% diameter demonstrated the greatest energy loss. The 25% banding model produced an energy loss of 16.76% systolic and 24.91% diastolic vs loose banding at 7.36% systolic and 17.90% diastolic. Also, restrictive PA bands had greater coronary flow compared with loose PA bands (50.2 vs 41.9 ml/min). Shear stress ranged from 3.75 Pascals with restrictive PA banding to 2.84 Pascals with loose banding. Intermediate PA banding at 50% diameter achieved a Qp/Qs (closest to 1) at 1.46 systolic and 0.66 diastolic compared with loose or restrictive banding without excess energy loss.
CFD provides a unique platform to simulate pressure, shear stress as well as energy losses of the hybrid procedure. PA banding at 50% provided a balanced pulmonary and systemic circulation with adequate coronary flow but without extra energy losses incurred.
Hypoplastic left heart syndrome; Computational fluid dynamics; Navier–Stokes equations; Haemodynamics; Simulations
To determine whether a cardiac diagnosis is a predictor of neurodevelopmental outcomes after infant cardiac surgery.
Infants with ventricular septal defect (VSD), tetralogy of Fallot (TOF), transposition of the great arteries (TGA), and hypoplastic left heart syndrome (HLHS) in a study of apolipoprotein E (APOE) polymorphisms, and neurodevelopmental outcome underwent neurodevelopmental and genetic evaluation at 4 years of age. The domains tested included cognition, language, speech, memory, executive function, visual-motor, fine motor, and reading and math skills.
Testing was completed in 178 patients with normal genetic evaluations: VSD (n = 26), TOF (n = 44), TGA (n = 41), and HLHS (n = 67). No differences were found in gestational age, ethnicity, APOE genotype, socioeconomic status, or maternal education among groups. Patient age at the first surgery was significantly lower for patients with TGA and HLHS compared with those with TOF and VSD. The postoperative length of stay was significantly longer for HLHS than all other groups and for TGA compared with TOF and VSD. HLHS correlated significantly with the use of deep hypothermic circulatory arrest and multiple operations. The mean scores for each domain were within normal limits for all groups. Compared with the other patients, those with HLHS had significantly lower scores for cognition, fine motor skills, executive function, and math skills. No significant differences were found among the TGA, TOF or VSD patients for any domain. Significant impairments in at least 1 domain were identified in 8% (2/25) of patients with VSD, 20% (8/41) with TOF, 17% (7/41) with TGA, and 18% (12/65) with HLHS. After correction for the demographic, preoperative, and operative variables, no significant differences were found among the groups for any domain.
The mean scores for the neurodevelopmental outcomes domains tested were in the normal range for preschool children with no recognized genetic syndromes after surgery for VSD, TOF, TGA, and HLHS. In each diagnostic group, the number of children with impairments in at least 1 domain increased compared with the general population. Unadjusted neurodevelopmental outcomes for HLHS were lower for cognition, fine motor skills, executive function, and math skills compared with the other patients. After correction for the demographic, preoperative, and operative variables, no significant differences were found among the groups for any domain. The specific cardiac diagnosis determines a large portion of the variation in these covariates. Therefore, although HLHS did predict for poorer outcomes in some domains, it did not add predictive power to the other factors considered.
To describe a 12 year experience with staged surgical management of the hypoplastic left heart syndrome (HLHS) and to identify the factors that influenced outcome.
Between December 1992 and June 2004, 333 patients with HLHS underwent a Norwood procedure (median age 4 days, range 0–217 days). Subsequently 203 patients underwent a bidirectional Glenn procedure (stage II) and 81 patients underwent a modified Fontan procedure (stage III). Follow up was complete (median interval 3.7 years, range 32 days to 11.3 years).
Early mortality after the Norwood procedure was 29% (n = 95); this decreased from 46% (first year) to 16% (last year; p < 0.05). Between stages, 49 patients died, 27 before stage II and 22 between stages II and III. There were one early and three late deaths after stage III. Actuarial survival (SEM) was 58% (3%) at one year and 50% (3%) at five and 10 years. On multivariable analysis, five factors influenced early mortality after the Norwood procedure (p < 0.05). Pulmonary blood flow supplied by a right ventricle to pulmonary artery (RV‐PA) conduit, arch reconstruction with pulmonary homograft patch, and increased operative weight improved early mortality. Increased periods of cardiopulmonary bypass and deep hypothermic circulatory arrest increased early mortality. Similar factors also influenced actuarial survival after the Norwood procedure.
This study identified an improvement in outcome after staged surgical management of HLHS, which was primarily attributable to changes in surgical technique. The RV‐PA conduit, in particular, was associated with a notable and independent improvement in early and actuarial survival.
hypoplastic left heart syndrome; Norwood procedure; risk factors; congenital heart defects; paediatrics
Hypoplastic left heart syndrome (HLHS) is one of the most common severe congenital cardiac anomalies, characterized by marked hypoplasia of left sided structures of the heart which is commonly accompanied by a thick layer of fibro-elastic tissue, termed endocardial fibroelastosis (EFE). Because human EFE develops only in fetal or neonatal hearts, and often in association with reduced blood flow, we sought to mimic these conditions by subjecting neonatal and 2-week-old rat hearts to variations of the heterotopically transplanted heart model with either no intracavitary or normal flow, and compare endocardium with human EFE tissue.
Methods and Methods
Hearts obtained from neonatal and 2-week-old rats were heterotopically transplanted in young adult Lewis rats in a working (loaded) or non-working (unloaded) mode. After 2 weeks survival, hearts were explanted for histological analysis by staining for collagen, elastin and cellular elements. These sections were compared to human EFE tissue from HLHS.
EFE, consisting of collagen and elastin with scarce cellular and vascular components, developed only in neonatal unloaded transplanted hearts and displayed the same histopathologic findings as EFE from patients with HLHS. Loaded hearts and 2-week-old hearts did not show these alterations.
This animal model for EFE will serve as a tool to study the mechanisms of EFE formation, such as fluid forces, in HLHS in a systematic manner. A better understanding of the underlying cause of EFE formation in HLHS will help develop novel treatment strategies to better preserve growth of the hypoplastic left ventricle.
endocardial fibroelastosis; hypoplastic left heart syndrome; animal model
The acute change in pulmonary artery pressure in response to oxygen may have prognostic value for patients with chronic obstructive pulmonary disease treated with long term domiciliary oxygen. A study was carried out to elucidate the mechanism of the acute cardio-respiratory response to oxygen in such patients and to determine whether it can be quantified non-invasively. The effects of acute oxygen administration (100% for 20 minutes and 28% oxygen for 24 hours) were assessed by non-invasive means and right heart catheterisation in 17 patients with severe stable hypoxaemic chronic obstructive pulmonary disease. Measurements included change in the ratio of dead space to tidal volume (VD/VT), effective pulmonary capillary blood flow (by rebreathing and single breath soluble gas uptake: QRB, QSB), left ventricular ejection fraction (radionuclide ventriculography), and M mode echocardiographic estimates of ventricular diameters and fractional shortening. These values were compared with those obtained from right heart catheter measurements of pulmonary artery pressure, cardiac index (thermodilution and direct carbon dioxide Fick: QTD, QFICK), and pulmonary vascular resistance. Oxygen administration resulted in a significant fall in pulmonary artery pressure, QTD, and QRB and a significant increase in VD/VT. The fall in QRB after 100% oxygen breathing for 20 minutes correlated strongly with the fall in pulmonary artery pressure (r = 0.86). There was no correlation between the fall in pulmonary artery pressure and the fall in QSB or the risen in VD/VT. Left ventricular ejection fraction did not change significantly. Echocardiography was technically unsatisfactory because of lung hyperinflation. Apart from a possible relation between VO2max and fall in pulmonary artery pressure after 24 hours of 28% oxygen breathing (r = 0.49, p less than 0.1) none of the baseline respiratory function measurements predicted the fall in pulmonary artery pressure or QRB. It is concluded that the cardiopulmonary response to acute oxygen breathing in patients with hypoxic chronic obstructive pulmonary disease includes a reduction in pulmonary artery pressure and cardiac output and a redistribution of pulmonary blood flow, and that rebreathing measurements of effective pulmonary blood flow can be used to quantify this response non-invasively.
BACKGROUND--Progressive pulmonary vascular disease in surgically unrepaired transposition of the great arteries with or without ventricular septal defect had been frequently described in the past. Occurrence of progressive pulmonary vascular disease has been reported even after atrial switch procedure done at three months of age. With the advent of neonatal surgical repair, this problem is virtually non-existent. There is a small subgroup of infants with transposition of the great arteries who show pulmonary vascular disease in the neonatal period that can adversely affect the surgical outcome. The clinico-pathological correlation in this group of patients was studied. OBSERVATIONS--Three patients, with transposition of the great arteries and intact ventricular septum, who showed histological evidence of pulmonary vascular disease in the neonatal period or early infancy are described. Two of these patients, continued to have poor systemic oxygenation despite adequate atrial communication. One patient had a close ductus arteriosus within the first two hours of birth while on prostaglandin E1 infusion. CONCLUSIONS--In the absence of left ventricular outflow tract obstruction, a poor response to atrial septostomy suggests pulmonary hypertension and pulmonary vascular disease. Antenatal constriction of the ductus arteriosus may contribute to such changes in pulmonary vasculature.
OBJECTIVE--To define the lowest age at which the bidirectional superior cavopulmonary anastomosis can safely be used in infants with complex congenital heart defects. DESIGN--A retrospective analysis of clinical, echocardiographic, haemodynamic, and angiographic data in four consecutive patients undergoing bidirectional superior cavopulmonary anastomosis below the age of 2 months. PATIENTS--Between November 1990 and September 1993, four infants less than 8 weeks of age (3, 4, 6, and 7 weeks) underwent bidirectional superior cavopulmonary anastomosis as a primary palliation for complex heart disease. The indication for early surgical intervention was progression of cyanosis (n = 3) and high pulmonary blood flow causing heart failure (n = 1). In two infants with tricuspid atresia, surgery was performed through a right thoracotomy without the use of cardiopulmonary bypass. In one infant with double inlet left ventricle and discordant ventriculoarterial connection, cavopulmonary anastomosis was combined with an arterial switch procedure. The final infant had double inlet left ventricle with pulmonary atresia; the central pulmonary arteries were virtually discontinuous and each branch was supplied by a separate arterial duct. The central pulmonary arteries were reconstructed using the subaortic innominate vein. Temporary prostacyclin infusion was used in three patients in the immediate postoperative period. RESULTS--Early postoperative extubation (5, 7, and 48 h) was successful in three patients. The youngest child required ligation of the ductus arteriosus four days later because of severe upper body oedema. The postoperative course was complicated by prolonged effusions in two patients. All were alive and well 14-48 months postoperatively, with satisfactory systemic saturations (80-87%) and haemodynamic indices. CONCLUSIONS--This limited experience challenges the widely held belief that the bidirectional superior cavopulmonary anastomosis cannot be used as a primary palliation for complex heart disease in early infancy. A wider experience is required to determine the safety and indications for this approach.
Although antenatal diagnostic technique has considerably improved, precise detection and proper management of the neonate with congenital heart disease (CHD) is always a great concern to pediatricians. Congenital cardiac malformations vary from benign to serious conditions such as complete transposition of the great arteries (TGA), critical pulmonary and aortic valvular stenosis/atresia, hypoplastic left heart syndrome (HLHS), obstructed total anomalous pulmonary venous return (TAPVR), which the baby needs immediate diagnosis and management for survival. Unfortunately, these life threatening heart diseases may not have obvious evidence early after birth, most of the clinical and physical findings are nonspecific and vague, which makes the diagnosis difficult. High index of suspicion and astute acumen are essential to decision making. When patent ductus arteriosus (PDA) is opened widely, many serious malformations may not be noticed easily in the early life, but would progress as severe acidosis/shock/cyanosis or even death as PDA constricts after few hours to days. Ductus dependent congenital cardiac lesions can be divided into the ductus dependent systemic or pulmonary disease, but physiologically quite different from each other and treatment strategy has to be tailored to the clinical status and cardiac malformations. Inevitably early presentation is often regarded as a medical emergency. Differential diagnosis with inborn error metabolic disorders, neonatal sepsis, persistent pulmonary hypertension of the newborn (PPHN) and other pulmonary conditions are necessary. Urgent identification of the newborn at such high risk requires timely referral to a pediatric cardiologist, and timely intervention is the key in reducing mortality and morbidity. This following review deals with the clinical presentations, investigative modalities and approach to management of congenital cardiac malformations presenting in the early life.
Congenital heart disease; Early intervention