The effects of the ketone body ß-hydroxybutyrate on isolated rat ventricular myocyte excitation-contraction coupling.

ß-hydroxybutyrate is the primary ketone body produced by the body during ketosis and is used to meet its metabolic demands. The healthy adult heart derives most of its energy from fatty acid oxidation. However, in certain diseases, the heart alters its substrate preference and increases its ketone body metabolism. Little is known about the effects of ßOHB on ventricular myocyte excitation-contraction coupling. Therefore, we examined the effects of ketone body metabolism on single cell excitation-contraction coupling during normoxic and hypoxic conditions. Myocytes were isolated from adult rats, cultured for 18 h in RPMI 1640, RPMI 1640 no glucose, and M199, HEPES with/without various amount of ßOHB added. To simulate hypoxia, myocytes were incubated at 1%O2, 5% CO2 for 1 h followed by incubation at atmospheric oxygen (21%O2,5% CO2) for 30 min before recordings. Recordings were obtained using an IonOptix system at 36±1ᵒ C. Myocytes were paced at 0.5, 1, 2, 3, and 4 Hz. We found that exposure to ßOHB had no effect on excitation-contraction coupling. However, culturing cells with ßOHB results in a significant increase in both contraction and calcium in RPMI 1640 media. Dose response experiments demonstrated 0.5 mM ßOHB is enough to increase myocyte contraction in the absence of glucose. However, ßOHB has no measurable effects on myocytes cultured in a nutrient rich media, M199, HEPES. Therefore, ßOHB improves single cell excitation-contraction coupling, is protective against hypoxia, and may be a beneficial adaptation for the heart during periods of nutrient scarcity and or metabolic dysregulation.

Impaired mitophagy facilitates mitochondrial damage in Danon disease.

RATIONALE: Lysosomal associated membrane protein type-2 (LAMP-2) is a highly conserved, ubiquitous protein that is critical for autophagic flux. Loss of function mutations in the LAMP-2 gene cause Danon disease, a rare X-linked disorder characterized by developmental delay, skeletal muscle weakness, and severe cardiomyopathy. We previously found that human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) from Danon patients exhibited significant mitochondrial oxidative stress and apoptosis. Understanding how loss of LAMP-2 expression leads to cardiomyocyte dysfunction and heart failure has important implications for the treatment of Danon disease as well as a variety of other cardiac disorders associated with impaired autophagy. OBJECTIVE: Elucidate the pathophysiology of cardiac dysfunction in Danon disease. METHODS AND RESULTS: We created hiPSCs from two patients with Danon disease and differentiated those cells into hiPSC-CMs using well-established protocols. Danon hiPSC-CMs demonstrated an accumulation of damaged mitochondria, disrupted mitophagic flux, depressed mitochondrial respiratory capacity, and abnormal gene expression of key mitochondrial pathways. Restoring the expression of LAMP-2B, the most abundant LAMP-2 isoform in the heart, rescued mitophagic flux as well as mitochondrial health and bioenergetics. To confirm our findings in vivo, we evaluated Lamp-2 knockout (KO) mice. Impaired autophagic flux was noted in the Lamp-2 KO mice compared to WT reporter mice, as well as an increased number of abnormal mitochondria, evidence of incomplete mitophagy, and impaired mitochondrial respiration. Physiologically, Lamp-2 KO mice demonstrated early features of contractile dysfunction without overt heart failure, indicating that the metabolic abnormalities associated with Danon disease precede the development of end-stage disease and are not merely part of the secondary changes associated with heart failure. CONCLUSIONS: Incomplete mitophagic flux and mitochondrial dysfunction are noted in both in vitro and in vivo models of Danon disease, and proceed overt cardiac contractile dysfunction. This suggests that impaired mitochondrial clearance may be central to the pathogenesis of disease and a potential target for therapeutic intervention.

Prospective trial of a pediatric ventricular assist device.

BACKGROUND: Options for mechanical circulatory support as a bridge to heart transplantation in children with severe heart failure are limited. METHODS: We conducted a prospective, single-group trial of a ventricular assist device designed specifically for children as a bridge to heart transplantation. Patients 16 years of age or younger were divided into two cohorts according to body-surface area (cohort 1, <0.7 m(2); cohort 2, 0.7 to <1.5 m(2)), with 24 patients in each group. Survival in the two cohorts receiving mechanical support (with data censored at the time of transplantation or weaning from the device owing to recovery) was compared with survival in two propensity-score-matched historical control groups (one for each cohort) undergoing extracorporeal membrane oxygenation (ECMO). RESULTS: For participants in cohort 1, the median survival time had not been reached at 174 days, whereas in the matched ECMO group, the median survival was 13 days (P<0.001 by the log-rank test). For participants in cohort 2 and the matched ECMO group, the median survival was 144 days and 10 days, respectively (P<0.001 by the log-rank test). Serious adverse events in cohort 1 and cohort 2 included major bleeding (in 42% and 50% of patients, respectively), infection (in 63% and 50%), and stroke (in 29% and 29%). CONCLUSIONS: Our trial showed that survival rates were significantly higher with the ventricular assist device than with ECMO. Serious adverse events, including infection, stroke, and bleeding, occurred in a majority of study participants. (Funded by Berlin Heart and the Food and Drug Administration Office of Orphan Product Development; ClinicalTrials.gov number, NCT00583661.).

Berlin Heart EXCOR pediatric ventricular assist device for bridge to heart transplantation in US children.

BACKGROUND: Recent data suggest that the Berlin Heart EXCOR Pediatric ventricular assist device is superior to extracorporeal membrane oxygenation for bridge to heart transplantation. Published data are limited to 1 in 4 children who received the device as part of the US clinical trial. We analyzed outcomes for all US children who received the EXCOR to characterize device outcomes in an unselected cohort and to identify risk factors for mortality to facilitate patient selection. METHODS AND RESULTS: This multicenter, prospective cohort study involved all children implanted with the Berlin Heart EXCOR Pediatric ventricular assist device at 47 centers from May 2007 through December 2010. Multiphase nonproportional hazards modeling was used to identify risk factors for early (<2 months) and late mortality. Of 204 children supported with the EXCOR, the median duration of support was 40 days (range, 1-435 days). Survival at 12 months was 75%, including 64% who reached transplantation, 6% who recovered, and 5% who were alive on the device. Multivariable analysis identified lower weight, biventricular assist device support, and elevated bilirubin as risk factors for early mortality and bilirubin extremes and renal dysfunction as risk factors for late mortality. Neurological dysfunction occurred in 29% and was the leading cause of death. CONCLUSIONS: Use of the Berlin Heart EXCOR has risen dramatically over the past decade. The EXCOR has emerged as a new treatment standard in the United States for pediatric bridge to transplantation. Three-quarters of children survived to transplantation or recovery; an important fraction experienced neurological dysfunction. Smaller patient size, renal dysfunction, hepatic dysfunction, and biventricular assist device use were associated with mortality, whereas extracorporeal membrane oxygenation before implantation and congenital heart disease were not.

Long-term Results Using Glutaraldehyde-treated Homograft Pericardium in Congenital Heart Surgery.

BACKGROUND: This study reports the long-term outcomes using glutaraldehyde-treated cryopreserved homograft pericardium (CPH) in neonates, infants, children, and young adults undergoing congenital cardiac surgery. METHODS: A retrospective review was performed of all patients at a single institution (Rady Children's Hospital, San Diego, CA) who had undergone surgical implantation with CPH between 2006 and 2016. The study identified 134 consecutive patients who underwent implantation of a total of 276 patches. The baseline demographic characteristics, primary cardiac diagnosis, surgical characteristics, operative reports, and postoperative catheterization and reoperation reports were analyzed. The use of CPH was categorized by specific anatomic insertion site. RESULTS: The median age at patch implantation was 1.47 years (range, 1 day to 31.6 years). The numbers and locations of patch use were 124 for pulmonary arterial repair, 57 for repair of the aorta, 49 for septal repair, and 43 at other sites. At a median follow-up of 5.29 years, 9 patients had died (6.7%), but none of those deaths were related to CPH. Twelve patients (8.96%) underwent reoperations, and 18 patients (13.4%) underwent catheter interventions at sites of CPH implantation. The 10-year freedom from patch-induced reoperation and catheter intervention rates were 88.5% and 86.9%, respectively. Overall patch failure-free survival was 85.8% and 79.0% at 5 and 10 years, respectively. CONCLUSIONS: The use of CPH patch in the surgical correction of congenital heart disease is effective and durable, as evidenced by the low reintervention rates. These results are comparable to the early and midterm outcomes of other similarly used surgical patches.

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.

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.

Modulation of cardiac performance by motor protein gene transfer.

Cardiac muscle performance can be determined by factors intrinsic to each cardiac muscle cell, such as protein isoform expression. One protein whose expression plays a major role in determining cardiac performance is myosin. Myosin is the heart's molecular motor which transduces the chemical energy from ATP hydrolysis into the mechanical energy of each heartbeat. Alterations of myosin isoform expression are routinely associated with acquired and inherited cases of cardiomyopathy. For example, human heart failure is consistently associated with increased expression of a slow myosin motor isoform and a concomitant decreased expression of the heart's fast myosin motor isoform. Further, mutations of the cardiac myosin gene are the most common cause of inherited hypertrophic cardiomyopathy. Transgenic animal studies have provided insight into cardiac functional effects caused by myosin isoform gene switching (fast-to-slow myosin or slow-to-fast myosin) or by expression of a disease-related mutant motor. More direct structure-function analysis using acute gene transfer of myosin motors provides evidence that the inotropic state of cardiac muscle can be affected by motor protein isoform shifting independent of intracellular calcium handling. Because most therapies for the diseased heart target intracellular calcium handling, acute gene transfer of cardiac molecular motors to modulate heart performance offers a novel therapeutic strategy for the compromised heart. Although the development of safe vectors for therapeutic myosin gene delivery are in their infancy, studies focused on acute genetic engineering of the heart's molecular motor will provide a foundation for therapeutic vector development and insight into mechanisms that contribute to cardiomyopathy.

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.

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.

Trans-hepatic cannulation: a novel approach for placement of a pediatric percutaneous ventricular assist device.

Pediatric ventricular assist device (VAD) use is increasing. The TandemHeart PTVA system is a percutaneous VAD used in adults. Pediatric use is limited by cannula size. Trans-hepatic left atrial (LA) cannulation offers the possibility of shorter, larger-diameter cannulae, but specific requirements for cannula size and flow characteristics need to be developed. We evaluated the feasibility of trans-hepatic cannulation based on patient measurements and bench-top modeling. Two hundred patients admitted to the University of Michigan Pediatric CICU were evaluated. Patients over 14 years and dextrocardiac patients were excluded. The distance from the skin between the 10th and 11th ribs at the mid-axillary line to the left-heart border was measured on x-ray. LA size was measured on echocardiogram. From these measurements, prototype cannulae were fabricated. Benchtop testing of developed cannulae was performed with a pump speed of 8500 RPM and fluid viscosity of 4.0 cP at physiologic atrial and arterial pressures. Inlet pressure and deliverable flows were measured. The proposed design delivered sufficient flow with negative pressures low enough to avoid hemolysis. Trans-hepatic LA cannulation for percutaneous VAD placement is feasible. The shorter distance to the LA and larger hepatic vein size allows design of pediatric-appropriate cannulae with adequate flow rates.

Intermediate Results of Hybrid Versus Primary Norwood Operation.

BACKGROUND: In 2007 we began a hybrid program for hypoplastic left heart syndrome (HLHS) variants to potentially improve outcome in high-risk patients. During implementation we offered both hybrid and Norwood approaches to all risk categories. The purpose of this study was to perform a comparative analysis of intermediate survival. METHODS: Newborns were evaluated jointly for high-risk characteristics, including birth weight less than 2.5 kg, prematurity (especially < 35 weeks), central nervous system abnormalities, multiorgan failure, intact or severely restrictive atrial septum, severe ventricular dysfunction, and severe atrioventricular valve regurgitation. We prefer Norwood for standard risk and hybrid for high risk, but all groups crossed over into all treatment pathways resulting in the following 5 treatment groups: standard risk Norwood; high-risk Norwood; standard risk hybrid ductal stent (HDS); high-risk hybrid DS; and high-risk hybrid prostaglandin E1 (HPGE). We reviewed all consecutive patients from 2007 to 2012, obtained follow-up, and analyzed the results. RESULTS: Sixty-eight newborns presented (median 2.96 kg, 8 days); 29 (43%) were high and 39 (57%) were standard risk. There were 14 stage I hospital deaths strongly associated with risk: 3 of 39 standard (7.7%) and 11 of 29 high (38%, p = 0.002). Stage I discharge mortality was highest for high-risk Norwood and high-risk HPGE groups (p < 0.001). Actuarial survival up to 5 years demonstrated superior survival for Norwood versus hybrid (78.1% vs 56.4%, p = 0.0182). With risk stratification there was suboptimal survival for all 3 high-risk groups (p = 0.003); HDS fared better than HPGE but had higher birth weight (p < 0.001). CONCLUSIONS: While a risk-stratified approach for HLHS variant patients with selective use of hybrid palliation resulted in acceptable stage I mortality, the longer term mortality for high-risk patients remains higher than for standard risk regardless of treatment modality. Intrinsic patient risk factors (rather than treatment modality) likely determine long-term outcome in experienced centers. Our current high-risk approach has evolved to HPGE application with Norwood conversion whenever deemed medically possible.

Combined arterial switch and Senning operation for congenitally corrected transposition of the great arteries: patient selection and intermediate results.

OBJECTIVE: Late results after traditional methods of repair of congenitally corrected transposition of the great arteries are poor. The combined arterial switch and Senning (double switch) operation may improve outcomes by using the morphologically left ventricle and mitral valve in the systemic circulation. In this report we review patient selection and intermediate results after the double switch operation for congenitally corrected transposition of the great arteries. METHODS: Since 1993, a total of 35 patients with congenitally corrected transposition of the great arteries with two ventricles of adequate size and no valvular pulmonary stenosis were potential candidates for a double switch operation. Eleven were not yet in need of further treatment, and 1 died during evaluation. The remaining 23 patients were entered into a protocol leading to anatomic repair. Their hospital records were reviewed, and follow-up data were obtained to evaluate early and intermediate outcomes. RESULTS: The 23 patients were candidates for anatomic repair because of right ventricular dysfunction or tricuspid regurgitation (n = 15) or associated uncorrected defects (n = 8). Pulmonary artery banding was performed in a total of 15 patients, either for left ventricular retraining (n = 11) or for congestive heart failure (n = 4). In 2 patients, aged 12 and 14 years, retraining was unsuccessful because of left ventricular dysfunction. Four patients with banding are currently awaiting repair. Eight patients proceeded to undergo double switch operations without preliminary pulmonary artery banding. To date, 17 patients have undergone double switch operations, with no early or late mortality. One patient required cardiac transplantation for progressive left ventricular failure after a preliminary banding and double switch operation done at 7 years of age. Ventricular function and tricuspid regurgitation remained stable or improved in all other cases. No patient has surgically acquired arrhythmias or significant residual hemodynamic conditions. All patients are alive and clinically well at a mean follow-up of 36 months (range 1 month-8 years). CONCLUSIONS: Congenitally corrected transposition of the great arteries with a normal pulmonary valve and two adequate ventricles can be managed with combined arterial switch and Senning operation with excellent intermediate results. Reconditioning the left ventricle may not be suitable for older patients. Late follow-up will be necessary to determine whether this management strategy provides a survival advantage for these patients.

Primary closure for postoperative mediastinitis in children.

OBJECTIVES: Mediastinitis affects approximately 1% of children undergoing median sternotomy. Conventional therapy involves debridement followed by open wound care with delayed closure, days to weeks of closed suction or antimicrobial irrigation, and vacuum-assisted closure or muscle flap closure. We hypothesized that primary closure without prolonged suction or irrigation is an effective, less traumatic treatment for mediastinitis in children. METHODS: From January 1986 to July 2002, 6705 procedures involving median sternotomy were performed at the C. S. Mott Children's Hospital, resulting in 57 cases of mediastinitis (0.85%). Cases were divided into 2 groups, with 42 cases treated with primary closure and 15 cases treated with delayed or muscle flap closure. The 42 cases of primary closure comprised the primary study group of this institutional review board-approved, retrospective analysis. Patient demographics, surgical variables, mediastinitis-related parameters, and outcomes were evaluated. RESULTS: One patient had recurrent mediastinitis for an overall infection eradication rate of 97% (40/41). Three patients (7%) required re-exploration for suspected ongoing infection. Of these re-explorations, 1 patient had evidence of continued mediastinitis. The remaining 2 patients with sepsis of unclear cause had no clinical or culture evidence of recurrent infection. One of these patients ultimately died of sepsis without active mediastinitis for a hospital survival of 97% (41/42). No significant differences could be detected between the treatment successes and failures in this small cohort of patients. CONCLUSIONS: Simple primary closure is an effective means to treat selected cases of postoperative mediastinitis in children. The results compare favorably with other more lengthy or debilitating treatments.

Tricuspid valve repair in hypoplastic left heart syndrome.

OBJECTIVES: Currently, the survival for the Norwood procedure for hypoplastic left heart syndrome is approximately 90% in selected centers. However, the development of tricuspid regurgitation remains a significant obstacle to successful staged repair in a subset of these patients. The results of tricuspid valve repair in this challenging patient population remain largely unknown. METHODS: Twenty-eight patients with significant (3-4+) tricuspid regurgitation after the Norwood procedure required tricuspid valve repair from August 1995 through December 2002. The clinical and Doppler-echocardiographic data were reviewed to determine the efficacy of repair and patient outcome. RESULTS: Follow-up was 96% complete (27/28). Patients were divided into 2 groups on the basis of tricuspid regurgitation at late follow-up: those with a successful late outcome (0-2+) and those with a poor outcome (3-4+). There were 17 (63%) patients with a successful result and 10 (37%) with an adverse outcome. Age, weight, follow-up duration, valve anatomy, and stage of palliation were not significantly different between groups. Early postoperative 0 to 2+ regurgitation was associated with a durable result (P =.012) and preserved ventricular function (P =.04). Need for repair other than a partial annuloplasty was predictive of a poor outcome (P =.04). Overall survival was 67% (18/27). Survival was 94% (16/17) for patients with a successful late result versus 20% (2/10) for those with a poor outcome (P =.0002). CONCLUSIONS: Tricuspid valve repair can be accomplished in this challenging patient population with excellent results. Successful tricuspid valve repair is predictive of continued good valve function and preserved right ventricular function. Successful valve repair at late follow-up predicts excellent late survival.

Bilateral pulmonary artery banding for resuscitation in hypoplastic left heart syndrome.

We report a case of a hypoplastic left heart syndrome with a nearly intact atrial septum and an obstructed anomalous pulmonary to systemic venous connection. Surgical atrial septectomy followed by bilateral pulmonary artery banding provided an optimal condition for the Norwood operation.

Valve sparing aortic root replacement for dilatation of the pulmonary autograft and aortic regurgitation after the Ross procedure.

BACKGROUND: Aortic insufficiency secondary to progressive dilatation of the pulmonary autograft is being recognized with increasing frequency after the Ross procedure. We reviewed our experience with valve-sparing aortic root replacement concomitant with aortic annuloplasty to assess the effectiveness of this approach. METHODS: Four patients, aged 8 to 27 years, presented with moderate to severe aortic insufficiency associated with progressive root dilatation from 1 to 8 years after a Ross procedure. All patients had 0 to 1+ aortic insufficiency early after the Ross procedure, with a mean maximal sinus diameter of 37 mm (range 30 to 45 mm). At reoperation the maximum diameter of the root ranged from 45 to 55 mm (mean 50 +/- 4 mm). A valve-sparing aortic root replacement with annular reduction was performed. The annulus was decreased from a mean of 27 mm to 23 mm. For the root replacement, 1 patient underwent a standard root remodeling procedure; in the others, a separate piece of scalloped Dacron (C.R. Bard, Haverhill, PA) graft material was used for each sinus to facilitate optimal exposure. RESULTS: All 4 patients are in New York Heart Association functional class I at a mean follow-up of 6 months. The most recent echocardiography demonstrated 0 to 1+ aortic insufficiency with good left ventricular function. Histology of the excised pulmonary autograft walls demonstrated severe elastin fragmentation. CONCLUSIONS: Aortic root remodeling with annular reduction is an effective treatment for aortic root dilatation and aortic insufficiency after the Ross operation. This procedure allows correction of aortic insufficiency and avoids the need for a prosthetic valve and anticoagulation.

Premature failure of small-sized Shelhigh No-React porcine pulmonic valve conduit model NR-4000.

OBJECTIVE: Given the limited availability of small-sized cryopreserved pulmonary homografts, we implanted a series of Shelhigh No-React porcine pulmonic valve conduits (SPVC). The aim of this study was to evaluate the short-term performance following implantation. METHODS: From February 2000 to September 2000, the SPVC was implanted 25 times in 24 patients in the right ventricular outflow tract (RVOT) to correct congenital anomalies. The anatomical malformations were TOF/PA in eight patients, TGA/VSD/PS in four, truncus arteriosus in four, IAA/VSD/AS or AA in four, l-TGA/VSD in two and other in two. Age at operation was 2.8+/-3.9 years (mean+/-SD), including 12 patients under 1 year. The median conduit size was 14mm (range, 10-18). RESULTS: At a mean follow-up of 23+/-5 months, two late deaths (8%) have occurred. Although they were not primarily conduit related, both showed severe conduit stenosis. Twenty-one conduits (84%) showed mild to severe conduit stenosis, regurgitation or both. Two patients underwent balloon dilatation for distal conduit stenosis. Twelve conduits (48%) in 11 patients were removed at a median of 12 months (range, 2-18 months) due to RVOT obstruction in 11 and free conduit insufficiency with pseudoaneurysm in one. The typical findings of the explanted conduits were prominent intimal peel formation at the distal anastomosis without calcification. The actuarial freedom from reintervention at 18 months was 48+/-10%. CONCLUSIONS: Our experience of the SPVC with the diameter of 14mm or less has revealed a high incidence of distal conduit stenosis due to intimal peel formation resulting in early conduit failure. These findings have led us to abandon its use when other options are available.

Hypoplastic left heart syndrome: conventional surgical management.

Surgical palliation for hypoplastic left heart syndrome has become standard therapy in many centers throughout the world. Significant improvements in management, from preoperative diagnosis and intraoperative technique to postoperative care, have resulted in a dramatic increase in survival. With this improved survival, however, come new challenges and unforeseen problems. The first stage of the reconstructive surgery remains the highest risk procedure for the reason that establishing a stable circulation that is dependent on a single, volume-overloaded right ventricle with the potential for jeopardized coronary blood flow remains a surgical challenge. In this review, current management strategies for the conventional reconstructive surgical approach are examined.