Cardiac Society of Australia and New Zealand (CSANZ) Position Statement on the Follow-Up of Cardiovascular Implantable Electronic Devices 2022.

Recognising the need for a national approach for the recommended best practice for the follow-up of implanted cardiac rhythm devices to ensure patient safety, this document has been produced by the Cardiac Society of Australia and New Zealand (CSANZ). It draws on accepted practice standards and guidelines of international electrophysiology bodies. It lays out methodology, frequency, and content of follow-up, including remote monitoring; personnel, including physician, allied health, nursing and industry; paediatric and adult congenital heart patients; and special considerations including magnetic resonance imaging scanning, perioperative management, and hazard alerts.

Poor Myocardial Compaction in a Patient with Recessive MYL2 Myopathy.

Recessive mutations in the Myosin regulatory light chain 2 (MYL2) gene are the cause of an infantile-onset myopathy, associated with fatal myocardial disease of variable macromorphology. We here present the first Japanese family affected with recessive MYL2 myopathy. Affected siblings manifested typical features and the proband's autopsy findings were compatible with the diagnosis of noncompaction cardiomyopathy. The rapidly progressive clinical course of this recessive MYL2 cardiomyopathy highlights the crucial role of c-terminal tails in MYL2 protein in maintaining cardiac morphology and function.

Identification of liver fibrosis using the hepatic vein waveform in patients with Fontan circulation.

AIM: Liver fibrosis caused by congestive hepatopathy has emerged as an important complication after Fontan procedure. We evaluated the utility of the hepatic vein (HV) waveform using Doppler ultrasound for identification of liver fibrosis in Fontan patients. METHODS: We investigated the HV waveforms in 41 Fontan patients and assessed correlations with clinical parameters, liver fibrosis markers, and hemodynamic data. RESULTS: Based on our preliminary analysis of 64 adult patients with chronic liver disease who underwent liver biopsy, we classified HV waveforms into five types with reference to the degree of flattening (from type 1, normal triphasic waveform; to type 5, a monophasic waveform indicating cirrhosis), and confirmed a significant correlation between waveform pattern and fibrosis stage. Notably, we detected HV waveforms in all of the Fontan patients and classified them into five types. The HV waveform pattern positively correlated with γ-glutamyl transferase and hyaluronic acid levels, and negatively correlated with albumin level and platelet count, but did not correlate with central venous pressure or brain natriuretic peptide level, suggesting that HV waveform could reflect pathophysiological changes in the liver without being affected by hepatic congestion. The highest area under the receiver operating characteristic curve of the HV waveform for detecting advanced liver fibrosis, as defined by ultrasonic findings and clinical features, was 0.829 (81.8% sensitivity, 73.3% specificity), which was higher than that of other non-invasive fibrosis markers. CONCLUSIONS: Hepatic vein waveforms change in accordance with liver fibrosis progression in Fontan patients, and can be a useful indicator of liver fibrosis after the Fontan procedure.

Cardiac Rhythm Disturbances in Heterotaxy Syndrome.

OBJECTIVE: Heterotaxy syndrome is associated with complex cardiac malformations and cardiac conduction system abnormalities. Those with right atrial isomerism (RAI) have dual sinus nodes and dual atrioventricular nodes predisposing them to supraventricular tachycardia (SVT). Those with left atrial isomerism (LAI) lack a normal sinus node and are at risk of sinus node dysfunction (SND) and atrioventricular block (AV block). We report the occurrence and risk factors associated with arrhythmias in heterotaxy syndrome. METHODS: A retrospective review of all heterotaxy syndrome patients born and treated at our institution between 2000 and 2014 was performed. RESULTS: A total of 40 patients were identified; 16/40 (40%) with LAI and 24/40 (60%) with RAI. There were 12 deaths during follow-up [LAI 3/16 (19%), RAI 9/24 (38%); p = 0.30]. Twenty-one patients had arrhythmias during a mean follow-up period of 5.4 years; 14/16 (87%) in LAI and 7/24 (29%) in RAI (p < 0.001). Freedom from arrhythmia at 1,3,5 years of age was 75.0%, 37.9%, 22.7% in LAI, and 83.3%, 77.5%, 69.6% in RAI, respectively(p = 0.00261). LAI had a three-fold increase in developing arrhythmias. Left atrial isomerism was the only factor identified to be associated with arrhythmia occurrence. CONCLUSIONS: Arrhythmias were commonly seen in heterotaxy syndrome particularly in left isomerism with more than half of the patients having arrhythmias by 3 years of age. Atrial situs was the only risk factor identified to be associated with arrhythmias, and close follow-up is warranted in these patients.

Intravoxel incoherent motion imaging has the possibility to detect liver abnormalities in young Fontan patients with good hemodynamics.

INTRODUCTION: Liver fibrosis and cirrhosis are one of the critical complications in Fontan patients. However, there are no well-established non-invasive and quantitative techniques for evaluating liver abnormalities in Fontan patients. Intravoxel incoherent motion diffusion-weighted imaging with MRI is a non-invasive and quantitative method to evaluate capillary network perfusion and molecular diffusion. The objective of this study is to assess the feasibility of intravoxel incoherent motion imaging in evaluating liver abnormalities in Fontan children. MATERIALS AND METHODS: Five consecutive Fontan patients and four age-matched healthy volunteers were included. Fontan patients were 12.8 ± 1.5 years old at the time of MRI scan. Intravoxel incoherent motion imaging parameters (D, D*, and f values) within the right hepatic lobe were compared. Laboratory test, ultrasonography, and cardiac MRI were also conducted in the Fontan patients. Results of cardiac catheterization conducted within one year of the intravoxel incoherent motion imaging were also examined. RESULTS: In Fontan patients, laboratory test and liver ultrasonography showed almost normal liver condition. Cardiac catheter and MRI showed good Fontan circulation. Cardiac index was 2.61 ± 0.23 L/min/m2. Intravoxel incoherent motion imaging parameters D, D*, and f values were lower in Fontan patients compared with controls (D: 1.1 ± 0.0 versus 1.3 ± 0.2 × 10-3 mm2/second (p = 0.04), D*: 30.8 ± 24.8 versus 113.2 ± 25.6 × 10-3 mm2/second (p < 0.01), and f: 13.2 ± 3.1 versus 22.4 ± 2.4% (p < 0.01), respectively). CONCLUSIONS: Intravoxel incoherent motion imaging is feasible for evaluating liver abnormalities in children with Fontan circulation.

Current Trends in Implantable Cardioverter-Defibrillator Therapy in Children　- Results From the JCDTR Database.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) are being used with increasing frequency in children. Our aim was to examine the current trend of pediatric ICD implantation in Japan. Methods and Results: Data was extracted from the Japanese Cardiac Device Treatment Registry (JCDTR), a nation-wide registry started in 2006. All patients aged less than 18 years who had an ICD implantation registered between 2006 and 2016 were included in the analysis. A total of 201 patients were included, with a median age of 16 years (range 1-18). The underlying cardiac diagnosis was primary electrical disease (67%), cardiomyopathy (26%) and congenital heart disease (4%), with idiopathic ventricular fibrillation (29%) and long QT syndrome (21%) being the 2 most common diagnoses. Implantation indication was primary prevention in only 30 patients (15%). There were 27 patients (13%) aged ≤12 years, with a larger proportion of patients with cardiomyopathy (33%). The indication in younger children was secondary prevention in all cases. Younger children may be under-represented in our study given the nature of the database as it is a predominantly adult cardiology database. CONCLUSIONS: In the past decade, ICD implantation has been performed in approximately 20 children per year in Japan, mostly for secondary prevention. There was no increase in the trend nor a change in age distribution.

Risk Factors for Peri-Procedural Arterial Ischaemic Stroke in Children with Cardiac Disease.

Improved survival of children with congenital heart disease has led to increasing focus on neurodevelopmental outcome, as close to half of the infants undergoing cardiac surgery are affected by neurodevelopmental disability. Stroke is particularly important as it frequently results in permanent neurologic sequelae. The aim of this study was to investigate risk factors for peri-procedural arterial ischaemic stroke (AIS) in children with cardiac disease. A retrospective case-control analysis of children aged <18 years with radiologically confirmed AIS following a cardiac procedure admitted to the Royal Children's Hospital Melbourne between 1993 and 2010. Each case was matched with two controls with similar cardiac diagnosis, procedure type, age and date of procedure. Demographics and peri-procedural data were collected from medical records and departmental database. Fifty-two cases were identified. Multivariable analysis identified post-procedural infection (OR 6.1, CI 1.3-27, p = 0.017) and length of ICU stay (OR 4.0, CI 1.4-11, p = 0.009) as risk factors for AIS. Although the study is limited to a single-centre cohort, length of ICU stay and post-procedural infection were identified as risk factors for AIS. These findings demonstrate these factors to be important areas to focus attention for stroke prevention in children with cardiac disease.

A case report of truncus arteriosus with intact ventricular septum and crossed branch pulmonary arteries.

Background: Truncus arteriosus (TA) or persistent arterial trunk describes the presence of a solitary arterial trunk arising from the base of the heart, supported by a common ventriculoarterial junction. The trunk gives rise to the coronary arteries, systemic arteries, and at least one pulmonary artery. Truncus arteriosus is a rare congenital cardiac disease, and even rarer is the absence of ventricular septal defect. Case summary: We report a case of a 2-day-old infant who presented with cyanosis and a cardiac murmur. He was diagnosed with TA with intact ventricular septum (IVS), as well as crossed pulmonary arteries which was identified on pre-operative imaging. We describe the surgical management and short-term follow-up. Discussion: Our clinical case demonstrates a unique diagnosis and management of TA with IVS identified by pre-operative imaging with good surgical outcome.

Isoproterenol stress test during catheterization of patients with coarctation of the aorta.

BACKGROUND: The exercise test is considered useful in selecting high-risk patients with repaired coarctation of the aorta (CoA), but it is difficult to obtain the cooperation of pediatric patients. The present study determines the feasibility of the isoproterenol stress test (IST) among pediatric patients with CoA. METHODS: Thirteen patients with repaired or mild preoperative CoA aged 1-207 (median 13) months underwent 16 IST during cardiac catheterization. Peak-to-peak pressure gradients (PG) over the coarctation site were measured at baseline and at IST. Balloon angioplasty (BAP) was applied to patients with significant stenosis on angiography. RESULTS: The PG between the ascending and the descending aorta was significantly higher at IST than at baseline (20.5 ± 11.5 vs 5.6 ± 3.9 mmHg, P < 0.0001). Heart rate, the systolic blood pressure measured at the ascending aorta, and pulse pressure were all significantly higher at IST than at baseline. The PG at IST decreased >10 mmHg in three of six patients after BAP. CONCLUSIONS: Significant pressure gradients over the coarctation site develop at IST in pediatric patients with repaired CoA or in preoperative patients with mild coarctation.

Impact and Modifiers of Ventricular Pacing in Patients With Single Ventricle Circulation.

BACKGROUND: Palliation of the single ventricle (SV) circulation is associated with a burden of lifelong complications. Previous studies have identified that the need for a permanent ventricular pacing system (PPMv) may be associated with additional adverse long-term outcomes. OBJECTIVES: The goal of this study was to quantify the attributable risk of PPMv in patients with SV, and to identify modifiable risk factors. METHODS: This international study was sponsored by the Pediatric and Congenital Electrophysiology Society. Centers contributed baseline and longitudinal data for functionally SV patients with PPMv. Enrollment was at implantation. Controls were matched 1:1 to PPMv subjects by ventricular morphology and sex, identified within center, and enrolled at matched age. Primary outcome was transplantation or death. RESULTS: In total, 236 PPMv subjects and 213 matched controls were identified (22 centers, 9 countries). Median age at enrollment was 5.3 years (quartiles: 1.5-13.2 years), follow-up 6.9 years (3.4-11.6 years). Median percent ventricular pacing (Vp) was 90.8% (25th-75th percentile: 4.3%-100%) in the PPMv cohort. Across 213 matched pairs, multivariable HR for death/transplant associated with PPMv was 3.8 (95% CI 1.9-7.6; P < 0.001). Within the PPMv population, higher Vp (HR: 1.009 per %; P = 0.009), higher QRS z-score (HR: 1.19; P = 0.009) and nonapical lead position (HR: 2.17; P = 0.042) were all associated with death/transplantation. CONCLUSIONS: PPMv in patients with SV is associated with increased risk of heart transplantation and death, despite controlling for increased associated morbidity of the PPMv cohort. Increased Vp, higher QRS z-score, and nonapical ventricular lead position are all associated with higher risk of adverse outcome and may be modifiable risk factors.

Acute progressive mitral regurgitation resulting from chordal rupture in infants.

This report describes six previously healthy infants with acute mitral valve chordal rupture. Although their initial symptoms were mild respiratory distress and fever, all the infants presented with acute progressive left heart failure and required urgent surgical repair. Mitral valve annuloplasty and mitral valve replacement were performed (for three patients each). Two patients died, both of whom had cardiac arrest and required resuscitation before surgery. Histologic examination of excised mitral valve leaflets showed infiltration of gram-positive bacteria in these two patients. All the patients were 4-6 months old, which may suggest underlying congenital factors. The authors believe early diagnosis and surgery are crucial as a life-saving measure for infants with acute mitral valve chordal rupture.

Severe pallid breath-holding spells treated with low-dose theophylline.

BACKGROUND: The medical treatment for severe pallid breath-holding spells accompanied with severe bradycardia or transient cardiac arrest is controversial. Although various medications have been reported to be effective, patients treated with pacemaker insertion are not always evaluated for pharmacological therapy beforehand. CASE REPORT: A 9-month-old boy developed pallid breath-holding spells. At 15 months of age, a Holter electrocardiogram revealed 12 s of asystole during a breath-holding spell. Treatment with low-dose theophylline sustained-release dry syrup (5.3 mg/kg/day) led to complete control of the spells. The peak concentration of theophylline was 4.4 µg/mL which was below the therapeutic range for bronchial asthma. When he turned 3 years and 5 months of age, theophylline treatment was discontinued without recurrence of pallid breath-holding spells. DISCUSSION: Theophylline is now infrequently used to treat pediatric bronchial asthma due to its limited effect coupled with its side effects, which include headache, digestive symptoms, and theophylline-associated convulsions. The effectiveness of theophylline as a treatment for pallid breath-holding spells has been reported in several reports. In our case, the theophylline dosage was approximately half the amount described in previous reports. CONCLUSIONS: In this case, low-dose theophylline was adequate in controlling the pallid breath-holding spells. Because theophylline-associated seizures are a major concern, we suggest an evaluation of low-dose theophylline for treating patients with severe pallid breath-holding spells without febrile convulsions or epilepsy before proceeding with permanent pacemaker insertion. Further development of preventive strategies for theophylline-associated seizures and characterization of patients who respond well to theophylline treatment is required.

Successful angioplasties using high pressure large balloons in a patient with severe anastomotic pulmonary artery stenosis soon after single-lung transplantation.

A 59-year-old man received a single-lung transplantation due to interstitial pneumonitis. Severe anastomotic pulmonary artery stenosis (PAS) resulting in hypoxia and respiratory symptoms was found in the immediate postoperative period. A scintigraphy showed severe hypoperfusion of the left transplanted lung with 7% of the total pulmonary blood flow. On postoperative days (POD) 29 and 64, the patient underwent serial balloon angioplasties without any complications. Based on the balloon selection criteria for PAS after heart surgery in children, a high-pressure large balloon was used with resultant improvement in respiratory signs and symptoms without any complications. The patient was discharged on POD 92. A follow-up scintigraphy on POD 169 revealed 58% of blood distribution to the left lung. The patient has been doing clinically well and remained asymptomatic one year after the transplantation. Balloon angioplasty with a high-pressure large balloon without stent implantation during an early postoperative period may be a safe and effective strategy. The balloon selecting criteria used in pediatric patients may be applied in the adult lung transplant recipients. .

Loss of ventricular preexcitation during noninvasive testing does not exclude high-risk accessory pathways: A multicenter study of WPW in children.

BACKGROUND: Abrupt loss of ventricular preexcitation on noninvasive evaluation, or nonpersistent preexcitation, in Wolff-Parkinson-White syndrome (WPW) is thought to indicate a low risk of life-threatening events. OBJECTIVE: The purpose of this study was to compare accessory pathway (AP) characteristics and occurrences of sudden cardiac arrest (SCA) and rapidly conducted preexcited atrial fibrillation (RC-AF) in patients with nonpersistent and persistent preexcitation. METHODS: Patients 21 years or younger with WPW and invasive electrophysiology study (EPS) data, SCA, or RC-AF were identified from multicenter databases. Nonpersistent preexcitation was defined as absence/sudden loss of preexcitation on electrocardiogram, Holter monitoring, or exercise stress test. RC-AF was defined as clinical preexcited atrial fibrillation with shortest preexcited R-R interval (SPERRI) ≤ 250 ms. AP effective refractory period (APERP), SPERRI at EPS , and shortest preexcited paced cycle length (SPPCL) were collected. High-risk APs were defined as APERP, SPERRI, or SPPCL ≤ 250 ms. RESULTS: Of 1589 patients, 244 (15%) had nonpersistent preexcitation and 1345 (85%) had persistent preexcitation. There were no differences in sex (58% vs 60% male; P=.49) or age (13.3±3.6 years vs 13.1±3.9 years; P=.43) between groups. Although APERP (344±76 ms vs 312±61 ms; P<.001) and SPPCL (394±123 ms vs 317±82 ms; P<.001) were longer in nonpersistent vs persistent preexcitation, there was no difference in SPERRI at EPS (331±71 ms vs 316±73 ms; P=.15). Nonpersistent preexcitation was associated with fewer high-risk APs (13% vs 23%; P<.001) than persistent preexcitation. Of 61 patients with SCA or RC-AF, 6 (10%) had nonpersistent preexcitation (3 SCA, 3 RC-AF). CONCLUSION: Nonpersistent preexcitation was associated with fewer high-risk APs, though it did not exclude the risk of SCA or RC-AF in children with WPW.

Life-Threatening Event Risk in Children With Wolff-Parkinson-White Syndrome: A Multicenter International Study.

OBJECTIVES: This study sought to characterize risk in children with Wolff-Parkinson-White (WPW) syndrome by comparing those who had experienced a life-threatening event (LTE) with a control population. BACKGROUND: Children with WPW syndrome are at risk of sudden death. METHODS: This retrospective multicenter pediatric study identified 912 subjects ≤21 years of age with WPW syndrome, using electrophysiology (EPS) studies. Case subjects had a history of LTE: sudden death, aborted sudden death, or atrial fibrillation (shortest pre-excited RR interval in atrial fibrillation [SPERRI] of ≤250 ms or with hemodynamic compromise); whereas subjects did not. We compared clinical and EPS data between cases and subjects. RESULTS: Case subjects (n = 96) were older and less likely than subjects (n = 816) to have symptoms or documented tachycardia. Mean age at LTE was 14.1 ± 3.9 years of age. The LTE was the sentinel symptom in 65%, consisting of rapidly conducted pre-excited atrial fibrillation (49%), aborted sudden death (45%), and sudden death (6%). Three risk components were considered at EPS: SPERRI, accessory pathway effective refractory period (APERP), and shortest paced cycle length with pre-excitation during atrial pacing (SPPCL), and all were shorter in cases than in control subjects. In multivariate analysis, risk factors for LTE included male sex, Ebstein malformation, rapid anterograde conduction (APERP, SPERRI, or SPPCL ≤250 ms), multiple pathways, and inducible atrial fibrillation. Of case subjects, 60 of 86 (69%) had ≥2 EPS risk stratification components performed; 22 of 60 (37%) did not have EPS-determined high-risk characteristics, and 15 of 60 (25%) had neither concerning pathway characteristics nor inducible atrioventricular reciprocating tachycardia. CONCLUSIONS: Young patients may experience LTE from WPW syndrome without prior symptoms or markers of high-risk on EPS.

Minimally invasive, pericardial implantable cardioverter-defibrillator placement in a young child.

We report the successful minimally invasive placement of a pericardial implantable cardioverter-defibrillator (ICD) in a 16-kg child. A transvenous ICD dual coil was advanced through a small subxiphoid incision and screwed into the oblique sinus pericardium under fluoroscopic guidance. An additional sense-pace lead was sutured onto the right ventricular apex, and the generator was placed in the upper abdominal wall through the same incision. Threshold testing demonstrated successful defibrillation at 15 J. After implantation, the patient had two episodes of appropriate shock for ventricular fibrillation. The ICD system continues to show stable impedance at 6 months of follow-up.

Atrioventricular block after ASD closure.

OBJECTIVE: Secundum atrial septal defect (ASD) is a common congenital heart defect. There is limited data on both early and late atrioventricular (AV) block post ASD closure. The aim of this study was to determine the incidence and risk factors of AV block associated with ASD closure. METHODS: A retrospective analysis of all patients who underwent ASD closure either with a device or surgical method at the Royal Children's Hospital Melbourne between 1996 and 2010 was performed. Baseline demographics, procedural details and follow-up data were collected from medical records. RESULTS: A total of 378 patients were identified; 242 in the device group and 136 in the surgical group. Fourteen patients (3.7%) had AV block (1 with second degree and 13 with first degree) at a median follow-up of 28 months; 11/242 (4.5%) in the device group and 3/135 (2.2%) in the surgical group (p=0.39). Six patients had new-onset AV block after ASD closure. In the device subgroup, patients with AV block at follow-up had a larger indexed device size compared with those without (22 (15-31) vs 18(7-38), p=0.02). Multivariate analysis revealed the presence of AV block either pre procedure or post procedure to be the only variables associated with late AV block. CONCLUSIONS: Late AV block in patients with repaired ASD is rare and most likely independent of the technique used. In the device subgroup, the only risk factor identified to be associated with late AV block was the presence of either preprocedural or postprocedural AV block, so long-term follow-up for these patients should be provided.

Optimizing outcomes of catheter ablation in infants and toddlers.

Since the introduction of transcatheter ablation in the late 1980s, there has been significant technical development. With a very high success rate and low complication rate, ablation has now become the standard of care in children and adults. However, long-term data remain insufficient and the application of ablation therapy in small children is debatable. In this review, current treatment strategies and results in toddlers and infants will be discussed. There has been improvement in success rate and complication rate for ablation in small children. Technological advancements in non-fluoroscopic electroanatomical mapping systems (3D systems) have led to the reduction of radiation and have facilitated ablations in complex cases. However, long-term effects of ablation lesions in small children remain a potential concern.

Arterial ischemic stroke in children with cardiac disease.

OBJECTIVE: To describe the spectrum of cardiac disorders, timing in relation to interventional procedures, and outcome in children with cardiac disease and arterial ischemic stroke (AIS). METHODS: Children younger than 18 years with cardiac disease and radiologically confirmed AIS admitted to the Royal Children's Hospital Melbourne between 1993 and 2010 were retrospectively identified using ICD-9 and ICD-10 searches. RESULTS: Seventy-six children with cardiac disease and radiologically confirmed AIS were identified with the median age at diagnosis of 5 months (interquartile range 0-58). Cardiac lesions included cyanotic congenital heart disease (CHD) in 42 (55%), acyanotic heart disease in 24 (29%), cardiomyopathies/myocarditis in 6 (8%), infective endocarditis in 3 (4%), and primary arrhythmias in 3 (4%). Stroke occurred following cardiac procedures in 52 patients (68%): 41 post cardiac surgery (4.6 strokes per 1,000 surgical procedures) and 11 post cardiac catheterization (1.7 strokes per 1,000 catheterizations). The median time from procedure to diagnosis of stroke was 3 days (interquartile range 2-7), with 68% (95% confidence interval 58%-79%) of strokes estimated to occur within the periprocedural period. Prevalence of periprocedural stroke varied by diagnostic category, but was most common in patients with cyanotic CHD undergoing palliative surgery (22/2,256, 1%) (p < 0.005). There were 3 AIS-related deaths, and 54 survivors (84%) had persisting neurologic deficits. CONCLUSIONS: Infants with cyanotic CHD were most frequently affected by AIS during the periprocedural period. Prospective cohort studies are required to determine effective primary and secondary prevention strategies.

Impact of Blalock-Taussig shunt size on tricuspid regurgitation in hypoplastic left heart syndrome.

BACKGROUND: The prognosis for hypoplastic left heart syndrome (HLHS) has greatly improved over the past years, but there is still a significant risk of interstage mortality. Tricuspid valve regurgitation (TR) is known to be a risk factor for interstage mortality. We hypothesized that a modified Blalock-Taussig (BT) shunt with a smaller diameter would lead to a reduction in ventricular volume loading with a consequent reduction in TR. METHODS: A retrospective review of all patients with HLHS who had a Norwood procedure in our institution between 2006 and 2011 was performed. Patient demographic, echocardiographic, cardiac magnetic resonance imaging, and operative data were reviewed. The impact of BT shunt diameter on severity of TR at the time of bidirectional cavopulmonary connection (BCPC) was analyzed. RESULTS: Sixty-four neonates with HLHS underwent a Norwood procedure with a BT shunt. Thirty-two had a 3.5-mm BT shunt (3.5-mm group), and 32 had a 3.0-mm BT shunt (3.0-mm group). Survival to BCPC was 53 of 64 patients (83%) overall, with 25 of 32 patients (78%) in the 3.5-mm group and 28 of 32 (88%) in the 3.0-mm group (p = 0.51). The prevalence of significant TR (moderate or higher) before BCPC was 9 of 25 patients (36%) in the 3.5-mm group and 2 of 28 patients (7%) in the 3.0-mm group (odds ratio = 7.3; 95% confidence interval: 1.4-38; p = 0.018). Tricuspid valve repair was performed in 4 of 25 patients (16%) in the 3.5-mm group and 2 of 28 patients (7%) in the 3.0-mm group (p = 0.21). CONCLUSIONS: A smaller-diameter BT shunt reduces the prevalence of significant TR at the time of BCPC. Further investigation and long-term follow-up are required to determine potential complications of this surgical strategy.