New developments in the treatment of hypoplastic left heart syndrome.

Hypoplastic left heart syndrome (HLHS) was once a uniformly fatal disease, accounting the majority of neonatal deaths due to congenital heart defects. Twenty-five years of advances in the surgical and medical management of this disease have resulted in dramatic improvements in survival for these children. The goal for patients with HLHS should be survival of near 100% with a good quality of life. The advances described in this manuscript detail some of the new techniques used in the surgical and medical management. For infants undergoing staged reconstruction, the Norwood procedure is performed in the newborn period, followed by a hemi-Fontan operation at 6 months of age, and a modified Fontan operation at 1 to 2 years of age. A significant recent modification of the Norwood procedure is the placement of a right ventricle to pulmonary artery (RV-PA) conduit instead of a systemic artery to pulmonary shunt (modified Blalock-Taussig or BT shunt) as the source of pulmonary blood flow. Our recent experience with this modification demonstrated an incremental increase in survival, improved postoperative stability, and decreased inter-stage mortality. At catheterization, significant differences in hemodynamic parameters were present that were consistent with improved coronary blood flow, decreased volume load to the single right ventricle, and improved pulmonary artery growth in those patients with the RV-PA conduit. The 3rd stage in the surgical treatment of HLHS is the modified Fontan operation or cavo-pulmonary anastamosis. A new approach for Fontan completion is the placement of a stent covered with a thin layer of Goretex from the inferior vena cava to the hemi-Fontan baffle. This can be performed in the catheterization laboratory, with a decrease in post-procedure pleural effusions, lower mortality, and a shorter length of stay. The future of treatment for HLHS may eventually involve a single open-heart procedure with initial and final interventions being performed in the catheterization laboratory. Some cardiac centers perform transplantation for management of HLHS. Survival following transplantation has improved as advances in the pre- and post-operative management continue, along with new options for immunosuppression. Treatment for HLHS continues to evolve, as ongoing work has resulted in improved short and long-term survival. The future for children with this disease is encouraging as evidenced by the remarkable achievements made to date and the current worldwide interest and study of HLHS.

Insurance and education determine survival in infantile coarctation of the aorta.

Health outcomes are determined by case severity, physician decisions, and patient variables. In a population-based study between 1981 and 1989, 103 cases of infant coarctation of the aorta were diagnosed before one year of age. The goal of this study was to determine whether patient race, gender, income, and insurance status had effects on outcome of coarctation of the aorta that were distinct from the effect of case severity. Survival of infants with coarctation of the aorta, a common congenital cardiovascular malformation, is associated with greater maternal education and with having any health insurance but not with measures of severity. Infants without health insurance are 12.8 times more likely to die than infants with any health insurance. Fifty-five percent of all deaths in infant coarctation occur prior to surgical treatment. One-third of deaths occur without diagnosis. Outcome measures require knowledge of the entire population and of insurance status to inform policy.

Gastric pneumatosis following cardiac surgery.

Infiltration of the stomach wall by air, first described by Fraenkel in 1889 [3], is a very rare condition. We describe the first reported case of gastric pneumatosis occurring in a child with complex congenital heart disease after cardiac surgery.

Cellular mechanisms of altered contractility in the hypertrophied heart: big hearts, big sparks.

To investigate the cellular mechanisms for altered Ca2+ homeostasis and contractility in cardiac hypertrophy, we measured whole-cell L-type Ca2+ currents (ICa,L), whole-cell Ca2+ transients ([Ca2+]i), and Ca2+ sparks in ventricular cells from 6-month-old spontaneously hypertensive rats (SHRs) and from age- and sex-matched Wistar-Kyoto and Sprague-Dawley control rats. By echocardiography, SHR hearts had cardiac hypertrophy and enhanced contractility (increased fractional shortening) and no signs of heart failure. SHR cells had a voltage-dependent increase in peak [Ca2+]i amplitude (at 0 mV, 1330+/-62 nmol/L [SHRs] versus 836+/-48 nmol/L [controls], P<0.05) that was not associated with changes in ICa,L density or kinetics, resting [Ca2+]i, or Ca2+ content of the sarcoplasmic reticulum (SR). SHR cells had increased time of relaxation. Ca2+ sparks from SHR cells had larger average amplitudes (173+/-192 nmol/L [SHRs] versus 109+/-64 nmol/L [control]; P<0.05), which was due to redistribution of Ca2+ sparks to a larger amplitude population. This change in Ca2+ spark amplitude distribution was not associated with any change in the density of ryanodine receptors, calsequestrin, junctin, triadin 1, Ca2+-ATPase, or phospholamban. Therefore, SHRs with cardiac hypertrophy have increased contractility, [Ca2+]i amplitude, time to relaxation, and average Ca2+ spark amplitude ("big sparks"). Importantly, big sparks occurred without alteration in the trigger for SR Ca2+ release (ICa,L), SR Ca2+ content, or the expression of several SR Ca2+-cycling proteins. Thus, cardiac hypertrophy in SHRs is linked with an alteration in the coupling of Ca2+ entry through L-type Ca2+ channels and the release of Ca2+ from the SR, leading to big sparks and enhanced contractility. Alterations in the microdomain between L-type Ca2+ channels and SR Ca2+ release channels may underlie the changes in Ca2+ homeostasis observed in cardiac hypertrophy. Modulation of SR Ca2+ release may provide a new therapeutic strategy for cardiac hypertrophy and for its progression to heart failure and sudden death.

Anomalies of pulmonary veins: usefulness of spin-echo and gradient-echo MR images.

OBJECTIVE: We compared the value of spin-echo and gradient-echo MR images in the evaluation of anomalies of pulmonary veins. MATERIALS AND METHODS: Fourteen patients with a variety of developmental anomalies of pulmonary veins underwent MR imaging examination. Axial T1-weighted spin-echo and gradient-echo MR images were evaluated retrospectively on separate occasions during which visualization of normal and anomalous pulmonary veins was determined. RESULTS: Of 52 pulmonary veins, 46 (88%) were identified on T1-weighted spin-echo images and 50 (96%) on gradient-echo images. Two patients had atresia of both left pulmonary veins. Of 14 anomalous veins, 11 (79%) were revealed on spin-echo images and 13 (93%) on gradient-echo images. CONCLUSION: Both spin-echo and gradient-echo MR images were accurate in revealing anomalies of pulmonary veins. In our study, gradient-echo images were equal or superior to spin-echo images.

MR imaging of congenital anomalies of the thoracic veins.

Congenital anomalies of the thoracic veins are infrequent but important developmental abnormalities. Thoracic venous anomalies can be classified as systemic or pulmonary. Systemic venous anomalies are often incidental findings, whereas pulmonary venous anomalies are more likely to manifest with cyanosis and to be associated with congenital cardiac abnormalities, especially atrial septal defect. Magnetic resonance (MR) imaging provides excellent delineation of the abnormal vessels and associated cardiac defects. Conventional spin-echo (SE) techniques show blood flow as a signal void and are sufficient for demonstrating the aberrant venous anatomy in most cases. Gradient-echo images show flowing blood as high signal intensity and are useful for clarifying the course of anomalous veins when vessel walls are difficult to visualize on SE images. Phase-contrast images are valuable for ascertaining the direction of blood flow and thus provide a physiologic method of distinguishing the vertical vein of anomalous pulmonary venous return from a left superior vena cava. MR imaging is useful for delineating both the thoracic venous and accompanying intracardiac anomalies and is a valuable, complementary technique to echocardiography, angiography, and computed tomography in the evaluation of patients with these abnormalities.

Changes in right ventricular geometry and heart rate early after hemi-Fontan procedure.

To document and quantitate changes in right ventricular (RV) geometry and heart rate, we prospectively examined 35 consecutive patients with hypoplastic left heart syndrome under steady-state conditions (chloral hydrate sedation) before and after a bidirectional cavopulmonary anastomosis (hemi-Fontan) procedure. Right ventricular end-diastolic volume (RVEDV) was calculated as the product of RV cavity areas in two orthogonal planes divided by RV maximal length in either plane. After the hemi-Fontan procedure, RVEDV decreased by 33% from 33 +/- 13 to 22 +/- 11 mL (mean +/- standard deviation). Indexed RVEDV decreased from 86 +/- 37 to 57 +/- 28 mL/m2. The RV wall thickness at the diaphragm in subcostal frontal view (RVWD) increased by only 11% from 8 +/- 0.2 to 9 +/- 0.2 mm (p = not significant), but RVWD/RVEDV increased by 111% from 0.36 +/- 0.22 to 0.76 +/- 0.69 mm/mL (p = 0.002). The RV anterior wall thickness in subcostal sagittal view (RVWA) increased by only 13% from 7 +/- 0.2 to 8 +/- 0.2 mm (p = not significant), but RVWA/RVEDV increased by 103% from 0.31 +/- 0.20 to 0.63 +/- 0.54 mm/mL (p = 0.002). In 11 of 35 patients (31%), resting heart rate did not change (118 +/- 14 versus 108 +/- 9 beats/min; p = not significant); however, in 24 of 35 patients (69%), heart rate increased significantly (108 +/- 9 versus 127 +/- 10 beats/min; p = 0.05). In conclusion, RV wall thickness is high before the hemi-Fontan procedure and increases slightly in the first postoperative week.(ABSTRACT TRUNCATED AT 250 WORDS)

Evaluation of congenital heart disease with MR imaging: current and coming attractions.

Nearly 10 years of experience in the use of MR imaging for the diagnosis of congenital heart disease has accumulated. Although MR imaging is superior to other techniques in showing certain structures and abnormalities such as small central pulmonary arteries in tetralogy of Fallot, aortic coarctations, and venous connections in heterotaxia syndromes, it remains an ancillary tool to echocardiography and cardiac catheterization. In this review, we examine present limitations and advantages of conventional MR in the evaluation of congenital anomalies of the heart and great vessels and explore future developments that might bring MR imaging into the diagnostic mainstream. Key improvements now in development are ultrafast MR systems for acquisition of multiple real-time MR images (in 30 msec or less) and on-line three-dimensional computer reconstruction of the heart and great vessels. Improved display and understanding of complex anatomy, as well as more extensive functional analysis of hearts before and after surgery, should be the benefits of such developments.

Coronary artery abnormalities and right ventricular histology in hypoplastic left heart syndrome.

OBJECTIVES: To determine whether right ventricular preservation is compromised in any anatomic subgroup of hypoplastic left heart syndrome, we assessed the coronary artery anatomy and myocardial histologic features of 151 postmortem specimens with hypoplastic left heart syndrome. BACKGROUND: Although previous studies have shown that coronary artery abnormalities are more prominent in the subgroup of patients who have a patent mitral valve and obstructed aortic valve, it has not been established that these abnormalities compromise right ventricular perfusion. METHODS: Eighty-nine specimens with a patent mitral valve and aortic atresia, 52 with mitral and aortic atresia and 10 with patent mitral and aortic valves were examined. Histologic sections of the right ventricle, left ventricle and coronary arteries were obtained from 64 study hearts and 5 control hearts. RESULTS: Gross coronary anomalies included coronary-cameral communications (n = 29), single left coronary artery (n = 2), single right coronary artery (n = 1) and tortuosity (n = 19). Coronary-cameral communications and tortuosity were significantly associated with the subgroup that had mitral hypoplasia and aortic atresia. Coronary artery wall thickness relative to lumen diameter was not different among the subgroups. No areas of coronary artery stenosis or interruption were discovered. Although endocardial fibroelastosis of the left ventricle was strongly associated with the mitral hypoplasia and aortic atresia group, the right ventricular histologic findings were similar in all subgroups and were not differentially affected by older age. CONCLUSIONS: Although the incidence of coronary abnormalities is greater in patients with mitral hypoplasia and aortic atresia, in this study there was no apparent difference in perfusion of the right ventricle among the anatomic subgroups of hearts with hypoplastic left heart syndrome.

Outcome and assessment after the modified Fontan procedure for hypoplastic left heart syndrome.

BACKGROUND: We reviewed the outcome of 76 consecutive patients (age range, 5 months to 6 years; median age, 19 months) who underwent a modified Fontan procedure after initial palliative surgery for hypoplastic left heart syndrome (HLHS) between January 1984 and December 1989. METHODS AND RESULTS: Modifications of the Fontan procedure included transatrial baffle of pulmonary venous return to the tricuspid valve (n = 10) or inferior vena cava baffle within the right atrium to the superior vena caval-pulmonary artery anastomosis, with pulmonary artery augmentation (n = 66). Actuarial survival rates were 74% (1 month), 58% (12 months), 56% (2 years), and 52% (4 years). Of the 43 survivors, 25 patients have returned for postoperative cardiac catheterization at a medium of 13 months after the Fontan procedure. Mean +/- SD hemodynamic values were cardiac index, 2.8 +/- 0.6 l/min/m2; right arterial pressure, 11 +/- 2 mm Hg; pulmonary artery wedge pressure, 6 +/- 3 mm Hg; and arterial oxygen saturation, 94 +/- 3%. No patient had significant tricuspid or native pulmonary valve insufficiency. CONCLUSIONS: Survival after the Fontan procedure in patients with HLHS is comparable to survival after a Fontan procedure in patients with other complex congenital heart lesions. In the subgroup of patients with HLHS who survived both reconstructive surgery and a Fontan procedure and have been evaluated by cardiac catheterization after a Fontan procedure, the use of the right ventricle as the systemic ventricle yielded excellent intermediate results for Fontan physiology.

Hypoplastic left heart syndrome: hemodynamic and angiographic assessment after initial reconstructive surgery and relevance to modified Fontan procedure.

After undergoing initial reconstructive surgery for hypoplastic left heart syndrome performed between August 1985 and March 1989, 59 patients (age range 3 to 27 months, mean 13.8 +/- 4.5) underwent elective cardiac catheterization in anticipation of a modified Fontan procedure. Five important hemodynamic and anatomic features considered to be components of successful reconstructive surgery were specifically addressed. 1) Interatrial communication: Only two patients had a measured pressure difference of greater than 4 mm Hg across the atrial septum. 2) Tricuspid valve function: Angiography demonstrated significant tricuspid valve regurgitation in only five patients (moderate in two and severe in three). 3) Aortic arch: Pressure tracings from the right ventricle to the descending aorta revealed a gradient greater than 25 mm Hg in only two patients. 4) Pulmonary vasculature: Ten patients had a calculated pulmonary vascular resistance greater than 4 U.m2; 51 (86%) of the 59 patients had no evidence of distortion (stenosis or hypoplasia) of either the left or the right pulmonary artery. 5) Right ventricular function: Five patients had an end-diastolic pressure in the right ventricle greater than 12 mm Hg and two patients had qualitative assessment of decreased ventricular function. Comparison of catheterization data between survivors and nonsurvivors of the subsequent modified Fontan procedure showed that only significant tricuspid regurgitation is a possible predictor of poor outcome. After first stage reconstructive surgery for hypoplastic left heart syndrome, most survivors have favorable anatomy and hemodynamics at follow-up cardiac catheterization for a subsequent Fontan procedure.

Hypoplastic left heart syndrome. Outcome after initial reconstruction and before modified Fontan procedure.

The outcome and clinical course before modified Fontan procedure were reviewed for 200 patients with hypoplastic left heart syndrome who underwent initial reconstructive surgery between August 1985 and March 1989. The median age at the time of initial reconstruction was 6 days (range, 1 day to 7.2 months). In 28 patients, a right modified Blalock-Taussig shunt was used; in 172 patients, a central shunt was placed. Additional procedures (n = 41) performed in 38 patients (median age, 5 months; range, 6 days to 17.5 months) were revision of systemic-to-pulmonary shunt (n = 15), arch reconstruction (n = 8), balloon angioplasty of arch obstruction (n = 7), atrial septectomy (n = 4), pulmonary artery angioplasty (n = 2), tricuspid valve annuloplasty or replacement (n = 4), and modified Glenn shunt (n = 1). There was no significant difference in the frequency of additional procedures performed more than 30 postoperative days in the survivors compared with the nonsurvivors. Actuarial survival rates were 0.66 (1 month), 0.48 (12 months), and 0.44 (18 months). Seventy percent of all deaths occurred during the initial admission, with 32% resulting from acute cardiovascular collapse during the first postoperative day. There was no statistical difference in actuarial survival when assessed by the type of shunt used or by anatomical subtype or when the influence of additional interventions was considered. Substantial improvement in outcome may be possible if immediate perioperative mortality can be reduced. We speculate that some of the intermediate mortality (30 days to 1 year) may be related to the effects of chronic exposure of the right ventricle to volume overload at systemic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)