Training in paediatric cardiac surgery and the American Board of Thoracic Surgery.

Congenital heart surgery has evolved into its own specialty requiring unique techniques and skills. Recognizing the need to establish a special certification in congenital heart surgery, the American Board of Thoracic Surgery began the process in 2005, eventually granting the first certifications to qualified applicants in 2009. The American Council for Graduate Medical Education and the Thoracic Surgery Residency Review Committee have now approved specific training programs throughout the United States that will help to ensure the proper training of congenital heart surgeons for the future.

Left ventricular retraining: theory and practice.

Congenitally corrected transposition of the great arteries or l-transposition of the great arteries is characterized by discordance of both the atrioventricular and ventriculoarterial connections. Physiologic repair of associated conditions, whereby the morphologic right ventricle remains the systemic ventricle, has resulted in unsatisfactory long-term outcomes due to the development of right ventricular failure and tricuspid valve regurgitation. While intuitively attractive, anatomic repair also has inherent challenges and risks, particularly for those patients who present late and require left ventricular retraining. Although early and intermediate-term outcomes for anatomic repair have been encouraging, longer-term follow-up has demonstrated concern for late left ventricular dysfunction in this subgroup of patients. Continued monitoring of this challenging patient population will clarify late outcomes and inform clinical management in the future.

Pattern of recovery for transient complete heart block after open heart surgery for congenital heart disease: duration alone predicts risk of late complete heart block.

Transient complete heart block (TCHB) is defined as complete interruption of atrioventricular conduction (AVC) after cardiac surgery followed by return of conduction. This study aimed to assess the risk for the development of late complete heart block (LCHB) after recovery of TCHB and to examine the electrocardiographic and electrophysiologic properties of the AVC system after TCHB. Of the 44 patients in this study who experienced TCHB, 37 recovered completely. Seven patients progressed from TCHB to intermittent CHB or LCHB requiring pacemaker implantation. Preoperative, early postoperative, and late postoperative electrocardiograms as well as postoperative atrial stimulation were obtained. The results showed that the median duration of TCHB was 5 days in the TCHB group compared with 9 days in the LCHB group (p = 0.01). All 37 subjects with TCHB recovered AVC within 12 days, but only two with LCHB did so (p = 0.02). The risk of LCHB for the patients with 7 days of postoperative TCHB or longer was 13 times greater than for the patients with fewer than 7 days of TCHB (p = 0.01). The median late postoperative PR interval was slightly but significantly longer in the LCHB group than in the TCHB group (p = 0.02). In contrast, the electrophysiologic properties between the two groups did not differ significantly. From those findings, we concluded that delayed recovery of AVC after surgical TCHB (≥7 days), but not electrophysiologic properties of recovered AVC assessed early in the postoperative period strongly, predicts risk of LCHB. Follow-up evaluation of AVC is particularly indicated for the delayed recovery group.

Tricuspid valve repair in hypoplastic left heart syndrome.

Tricuspid valve regurgitation (TR) remains an obstacle for staged palliation of hypoplastic left heart syndrome (HLHS). Because previous results from our institution suggested that posterior leaflet obliteration (PLO) is effective in tricuspid valve repair (TVR), we preferentially used this method. This report analyzes the effect of this preference on repair success and patient survival. All HLHS patients with 3-4+ preoperative TR undergoing TVR between 2002 and 2007 were retrospectively analyzed. Clinical and echocardiographic data were used to determine outcomes. Seventy-one percent (17 of 24) of patients had success at early outcome; the remaining 29% experienced early failure. Sixty-three percent (15 of 24) of patients demonstrated success at late outcome. Early outcome status was found to be a predictor of late outcome status (OR 22.9, P = 0.0037). Overall survival was 71% (17 of 24). Survival could not be shown to be associated with early or late outcome status (odds ratio = 0.96). A preference for PLO was found to give improved, long-lasting results for HLHS patients. Success at immediate outcome was predictive of success with time. PLO has the advantage of being simple and reproducible and produces good outcomes in this challenging group. Continued follow-up will be necessary to confirm long-term outcomes.

Relationship of Ventricular Morphology and Atrioventricular Valve Function to Long-Term Outcomes Following Fontan Procedures.

BACKGROUND: The influence of ventricular morphology on Fontan outcomes is controversial. OBJECTIVES: This study hypothesized that dysfunction of the single right ventricle (RV) and right atrioventricular valve regurgitation (AVVR) increases over time and adversely impacts late outcomes following a Fontan operation. A single-center retrospective study was performed. METHODS: From 1985 through 2018, 1,162 patients underwent the Fontan procedure at our center and were included in this study. Transplant and takedown free survival, ventricular, and atrioventricular valve dysfunction after Fontan were analyzed. Death or heart transplantation information was obtained from the National Death Index and the Scientific Registry of Transplant Recipients. RESULTS: The follow-up rate was 99%. Morphologic RV was present in 58% of patients. Transplant and takedown free survival were 91%, 75%, and 71% at 10 years, 20 years, and 25 years, respectively. Morphologic RV was an independent risk factor for transplant, takedown free survival (hazard ratio: 2.4; p = 0.008). The AVVR, which preceded ventricular dysfunction in most cases, was associated with the development of ventricular dysfunction after Fontan (odds ratio: 4.3; 95% confidence interval: 2.7 to 6.7; p < 0.001). Furthermore, AVVR and ventricular dysfunction progressed over time after Fontan, especially in the RV (AVVR: p < 0.0001, ventricular dysfunction: p < 0.0001). CONCLUSIONS: Morphologic RV is negatively associated with the long-term survival following the Fontan, possibly due to a tendency toward progressive AVVR and deterioration of the single ventricle function. Additional volume overload caused by AVVR may be one of the main factors accelerating the dysfunction of the single RV, implying that early valve intervention may be warranted.

How I manage neonatal Ebstein's anomaly.

Ebstein's anomaly of the tricuspid valve is characterized by a wide spectrum of severity. The condition involves more than a malformation of the tricuspid valve alone; a substantial portion of the right ventricle may be involved as well. Those patients presenting with symptoms in the first month of life represent a challenging group with a high mortality and uncertainty as to the best treatment options. In this review, the practical decision making process and the outcomes for neonates at one center are discussed.

Fontan operation in the current era: a 15-year single institution experience.

OBJECTIVE: Evaluate current risk factors for mortality and morbidity in patients undergoing the Fontan procedure at a single institution in the current era. SUMMARY BACKGROUND DATA: An emphasis on early relief of volume and pressure overload culminating in the Fontan procedure has improved patient outcomes for patients with a single ventricle. METHODS: A cross-sectional retrospective study was performed for 636 primary Fontan procedures between July 1992 and June 2007. RESULTS: Anatomy included left ventricular hypoplasia in 64% and right ventricular hypoplasia in 36%. A lateral tunnel (LT) was performed in 92% and an extracardiac conduit (EC) in 8%. Hospital survival was 96%. Long-term survival was 97% at a mean follow-up of 50 months (range, 0-173 months). Ventricular anatomy and preoperative hemodynamics did not predict early or late survival. Longer aortic cross clamp (XC) time was associated with decreased late survival (P = 0.01). Fontan takedown was required in 3% and protein-losing enteropathy (PLE) developed in 6%. At follow-up, 98% of patients were either NYHA class I or II and 87% were in normal sinus rhythm. Patients with chest tube drainage >2 weeks had an increased risk of PLE (P < 0.0001) and diminished short- and long-term survival (P = 0.026 and P < 0.0001, respectively). CONCLUSIONS: The Fontan procedure can be performed with low risk regardless of ventricular anatomy. Duration of XC time is associated with survival. Prolonged CT drainage correlates with late PLE and diminished survival. There was a low prevalence of late rhythm disturbances and other complications.

Anomalies of left coronary artery origin affecting surgical repair of hypoplastic left heart syndrome and Shone complex.

There has traditionally been less concern regarding coronary anomalies with left-sided congenital heart lesions such as hypoplastic left heart syndrome (HLHS)or Shone complex than with other lesions. However, coronary anomalies in this setting can profoundly affect surgical intervention, particularly when surgical repair involves the ascending aorta. We describe four patients with congenital left-sided heart lesions in which left coronary artery (LCA) anomalies substantially affected intervention and outcome. In the first two cases, the coronary anomalies were not identified prospectively and resulted in surgical injury directly to the coronary or to its surrounding region. In the latter two cases, successful identification of the coronary anomaly preoperatively allowed for modification of surgical technique and/or intervention. We conclude that detailed coronary artery assessment should be part of the routine echocardiographic evaluation of congenital left-sided heart lesions that require surgery.

Mechanical Circulatory Support for the Failing Fontan: Conversion to Assisted Single Ventricle Circulation-Preliminary Observations.

BACKGROUND: Mechanical circulatory support (MCS) of a failing Fontan circulation remains challenging. We hypothesized that MCS can be provided by converting the Fontan circulation into a mechanically assisted single ventricle parallel circulation (MASVC). METHODS: A porcine model of functionally univentricular circulation was created under cardiopulmonary bypass (CPB) by performing an atrial septectomy, tricuspid valvectomy, and interrupting antegrade pulmonary blood flow. A centrifugal flow pump was placed with inflow from the common atrium. Eight millimeter Dacron grafts anastomosed to the ascending aorta and main pulmonary artery supplied systemic (Qs) and pulmonary (Qp) blood flow. Ultrasonic flow probes were used to measure Qs and Qp after weaning from CPB. The Qp/Qs ratio was regulated using an adjustable clamp. Hemodynamic and laboratory data were recorded. RESULTS: All four animals were successfully weaned from CPB onto the MASVC for a duration of two hours. Mechanically assisted single ventricle parallel circulation achieved satisfactory hemodynamics. As anticipated, the arterial oxygen saturation and partial pressure of oxygen in arterial blood were lower in the MASVC compared to baseline biventricular circulation. At the conclusion of the study, there was a trend towards a decrease in the mixed venous saturation with increasing oxygen extraction compared to the baseline. Serum lactate levels increased after weaning from CPB and did not return to baseline after two hours of support. CONCLUSION: Mechanically assisted single ventricle parallel circulation can be established in a single ventricle animal model. This strategy could potentially provide MCS of a single ventricle circulation. Studies with longer duration of support are required to assess adequacy of support and long-term sustainability.

Tricuspid valve repair for hypoplastic left heart syndrome and the failing right ventricle.

Tricuspid valve regurgitation in patients with hypoplastic left heart syndrome is a cause of significant morbidity and mortality. Due to the multifactorial nature of its etiology, repair of the tricuspid valve may not always address the underlying problem and fail to improve late outcome. The role of tricuspid valve repair in this condition was examined in a series of patients with severe regurgitation following a Norwood procedure. The influence of surgical technique and right ventricular function were assessed in relation to late survival and tricuspid valve function. Tricuspid valve repair was successfully performed in the majority of patients and contributed to improved late outcomes. However, patients with an initially successful repair but significant right ventricular dysfunction tended to do poorly and the function of the valve often continued to deteriorate. Those with preserved ventricular function, even with continued tricuspid regurgitation, fared much better and achieved good results with additional attempts at repair.

Multiscale modelling in biofluidynamics: application to reconstructive paediatric cardiac surgery.

Multiscale computing is a challenging area even in biomechanics. Application of such a methodology to quantitatively compare postoperative hemodynamics in congenital heart diseases is very promising. In the treatment of hypoplastic left heart syndrome, which is a congenital heart disease where the left ventricle is missing or very small, the necessity to feed the pulmonary and systemic circulations is obtained with an interposition shunt. Two main options are available and differ from the sites of anastomoses: (i) the systemic-to-pulmonary conduit (Blalock-Taussig shunt known as the Norwood Operation (NO)) connecting the innominate artery (NO-BT) or the aorta (NO-CS) to the right pulmonary artery and (ii) the right ventricle to pulmonary artery shunt (known as Sano operation (SO)). The proposition that the SO is superior to the NO remains controversial. 3-D computer models of the NO (NO-BT and NO-CS) and SO were developed and investigated using the finite volume method. Conduits of 3, 3.5 and 4 mm were used in the NO models, whereas conduits of 4, 5 and 6 mm were used in the SO model. The hydraulic nets (lumped resistances, compliances, inertances and elastances) which represent the systemic, coronary and pulmonary circulations and the heart were identical in the two models. A multiscale approach was adopted to couple the 3-D models with the circulation net. Computer simulation results were compared with post-operative catheterization data. Results showed that (i) there is a good correlation between predicted and observed data: higher aortic diastolic pressure, decreased pulmonary arterial pressure, lower pulmonary-to-systemic flow ratio and higher coronary perfusion pressure in SO; (ii) there is a minimal regurgitant flow in the SO conduit. The close correlation between predicted and observed clinical data supports the use of mathematical modelling, with a mandatory multiscale approach, in the design and assessment of surgical procedures.

Pulmonary vein stenosis following repair of total anomalous pulmonary venous connection.

Pulmonary vein stenosis may occur following the repair of total anomalous pulmonary venous connection and carries a poor prognosis. Conventional surgical therapies have been complicated by a high rate of re-stenosis. Sutureless pericardial marsupialization has been introduced as a technique to reduce the rate of re-stenosis. This report describes a retrospective review of a group of patients undergoing repair of acquired pulmonary vein stenosis. Presence of single-ventricle anatomy was found to be the primary preoperative risk factor for a poor outcome. The use of sutureless pericardial marsupialization was found to be associated with a significant improvement in disease-free survival.

Long-Term Survival and Freedom From Reoperation After Placement of a Pulmonary Xenograft Valved Conduit.

BACKGROUND: The optimal choice for pulmonary valve replacement (PVR) remains controversial. This study hypothesized that xenografts used for PVR would result in prolonged long-term survival and freedom from reoperation. METHODS: Children and adults with congenital heart disease requiring PVR using a xenograft from 1980 to 1985 were reviewed. In all cases, the xenograft valve was either sewn or manufactured into a Dacron conduit, and the conduit was sewn to the pulmonary artery bifurcation. Clinical data were analyzed, and survival and freedom from reoperation were determined using Kaplan-Meier analysis. RESULTS: Twenty-four patients received a xenograft for PVR at 14.6 ± 5.6 years. Conduit size ranged from 21 to 27 mm. Most patients received a Carpentier-Edwards valved conduit (n = 17), followed by a Hancock valved conduit (n = 5) and an Ionescu-Shiley valve sewn into a Dacron graft (n = 2). No perioperative deaths occurred. Reoperation was required mainly for pulmonary stenosis (72.7%), followed by pulmonary insufficiency (18.2%), or both stenosis and insufficiency (9%). Freedom from reoperation was 90%, 56%, 43%, and 14% at 10, 20, 25, and 30 years, respectively. At most recent follow-up the was only death, which was related to severe biventricular failure 25 years after conduit implant. CONCLUSIONS: PVR using a xenograft valved conduit results in prolonged freedom from reoperation and excellent long-term survival. These data, which provide long-term follow-up information on xenograft valves after PVR.

The University of Michigan Cardiac and Thoracic Surgery Program.

In 1928, the University of Michigan opened its thoracic surgery residency under the leadership of Dr John Alexander. Initially tasked with providing surgical care for patients with thoracic diseases such as tuberculosis, thoracic surgery subspecialties now provide surgical treatment for a spectrum of diseases, ranging from congenital cardiopulmonary abnormalities to thoracic malignancy to acquired heart and great vessel diseases. Both the residency and the medical center have evolved to mirror the changing practice of thoracic surgery.

Follow-Up of a Prospective Surgical Strategy to Prevent Intra-Atrial Reentrant Tachycardia After the Fontan Operation.

BACKGROUND: Intra-atrial reentrant tachycardia (IART) after the Fontan operation had an early reported incidence of 10% to 35% during early and intermediate follow-up and posed substantial management challenges. METHODS AND RESULTS: To reduce the incidence of IART after the Fontan procedure, we performed a randomized, double-blind study to evaluate the impact of an incision in the right atrium joining the lateral tunnel suture line and the tricuspid valve annulus. Between March 1998 and September 2003, 134 subjects (median age: 1.8 years; range: 1.3-5.2 years; 91 men) were randomly assigned to receive the incision. All 134 patients had a form of single ventricle pathological anatomy. The clinical course, electrocardiograms, and Holter monitoring were available for review in 114 subjects at a median of 8.2-year follow-up (range: 0.9-11.9 years). There were 2 late deaths, neither subject had IART. The combined incidence of sustained IART was 3.5% (4/114). There was no difference in the occurrence of sustained IART between those subjects receiving the incision and those who did not (2 in each group) during follow-up. No patients of either group experienced short-term complications. CONCLUSIONS: Despite the fact that the primary outcome of this trial was not reached, the most significant finding was that with current management, the incidence of IART is considerably lower than the early retrospective, observational studies suggested.

Risk factors for cerebrovascular events following fontan palliation in patients with a functional single ventricle.

The risk for cerebrovascular events (CVEs) is increased in children with functional single ventricles (FSVs). However, there are limited data indicating the prevalence of CVEs or the role of preventative therapy. To measure the prevalence of clinically evident CVEs in patients with FSVs, identify risk factors, and analyze the effect of aspirin on the risk for CVEs, a retrospective chart review was performed on all patients who underwent Fontan palliation at the University of Michigan from January 1, 1975, to June 30, 1998 (n = 402). Data collected included original anatomy, Fontan type, date of CVE, medications at the time of CVE, intraoperative placement of fenestration, and date of last follow-up. The overall mortality rate was 12%. There were 38 CVEs (9%), of which only 11 (3%, or 0.0036/patient-year) could not be attributed to a defined event (catheterization, extracorporeal membrane oxygenation, or cardiac arrest). Anticoagulation with aspirin was associated with a statistically significantly decreased risk for CVEs. Fontan type was not associated with the risk for CVEs. Thus, patients with FSVs are at increased risk for CVEs, although the de novo risk was low. Aspirin use is associated with a decreased risk for CVEs.

Multiscale modeling of the cardiovascular system: application to the study of pulmonary and coronary perfusions in the univentricular circulation.

The objective of this study is to compare the coronary and pulmonary blood flow dynamics resulting from two configurations of systemic-to-pulmonary artery shunts currently utilized during the Norwood procedure: the central (CS) and modified Blalock Taussig (MBTS) shunts. A lumped parameter model of the neonatal cardiovascular circulation and detailed 3-D models of the shunt based on the finite volume method were constructed. Shunt sizes of 3, 3.5 and 4 mm were considered. A multiscale approach was adopted to prescribe appropriate and realistic boundary conditions for the 3-D models of the Norwood circulation. Results showed that the average shunt flow rate is higher for the CS option than for the MBTS and that pulmonary flow increases with shunt size for both options. Cardiac output is higher for the CS option for all shunt sizes. Flow distribution between the left and the right pulmonary arteries is not completely balanced, although for the CS option the discrepancy is low (50-51% of the pulmonary flow to the right lung) while for the MBTS it is more pronounced with larger shunt sizes (51-54% to the left lung). The CS option favors perfusion to the right lung while the MBTS favors the left. In the CS option, a smaller percentage of aortic flow is distributed to the coronary circulation, while that percentage rises for the MBTS. These findings may have important implications for coronary blood flow and ventricular function.