Magnetic Resonance Imaging Predictors of Coarctation Severity

Congenital Heart Disease

disease. It is likely that overall survival and other outcomes would be more likely to continue to improve with the development of regional referral centers. CG

Abstracts The Effect of Surgical Case Volume on Outcome After the Norwood Operation

Mitral Valve Repair in Children With Rheumatic Heart Disease

Checchia PA, McCollegan J, Daher N, Kolovos N, Levy F, Markovitx B. J Thorac Cardiovasc Surg 2005;129:754 –9.

Talwar S, Rajesh MR, Subramanian A, Saxena A, Kumar AS. J Thorac Cardiovasc Surg 2005;129:875–9.

Study Question: What are the relative effects of surgical and institution experience on survival for children undergoing the Norwood operation? Methods: Data from the Pediatric Health Information System, a large multi-institutional database, was utilized for this study. Cases with the diagnosis of hypoplastic left heart syndrome (HLHS), less than 30 days of age at the time of admission, discharged between January 1, 1998, and December 31, 2001, and who had a Norwood operation were reviewed. Data collected included length of stay, disposition at discharge, mortality, non-Norwood medical–surgical procedures and surgeons per institution. Center volume was considered over 4 years, and institutions were categorized as low volume (⬍16 procedures), medium volume (16 –30 procedures) or higher volume (⬎30 procedures). Results: There were 1105 patients with the diagnosis of HLHS; 801 underwent the Norwood operation, 39 underwent transplant, and 265 did not undergo an intervention. Twentynine institutions were included in the analysis, with Norwoods performed ranging from 2–109 per institution. A total of 87 surgeons performed 10.7⫾14 Norwood procedures over the 4-year period. Overall, the survival rate to discharge was 68% and ranged from 25% to 100% among the institutions. Institutional volume, categorized as low, medium and higher volume, was not associated with survival. However, volume as a continuous variable was associated with improved survival. Surgeons who performed ⬍5 Norwood operations over the study period had survival rates of 49%. Two surgeons in the group averaged at least one Norwood operation per month, and survival rates for these two physicians were 75% and 92%. Institutional Norwood survival rates increased 4% for every 10 additional cases per institution over the course of the study period. Conclusions: Survival to discharge following the Norwood operation increases with higher institutional Norwood volume. Surgeon-specific volume was not associated with a statistically significant increase in survival, though the relative small size as well as the overlapping variables of institution and surgeon volume limits this analysis. Perspective: This study provides an interesting look at the role of the institution in survival for patients with HLHS. There is no question that both the skill and the experience of the surgeon are necessary for achieving survival for children with this condition. This study demonstrates that increased institutional volume is associated with improved survival and thus points to the importance of the whole team in caring for patients with this complex and high-risk

Study Question: What are the long-term results of mitral valve repair in children with chronic rheumatic heart disease? Methods: From January 1988 through December 2003, 278 children (153 males) underwent mitral valve repair at a single center in India. Mean age was 11.7⫾2.9 years (range 2–15 years). One hundred seventy-three children (62%) were in New York Heart Association functional class III or IV. Congestive heart failure was present in 24 (8.6%). Reparative procedures included posterior annuloplasty (n⫽242), commissurotomy (n⫽187), cusp-level chordal shortening (n⫽94), cusp thinning (n⫽71), cleft suture (n⫽65) and cusp excision or plication (n⫽10). Associated procedures included atrial septal defect closure (n⫽22), aortic valve repair/replacement (n⫽13) and tricuspid valve repair (n⫽3). Results: Early mortality was 2.2% (6 patients), and was associated with preoperative left ventricular systolic dysfunction. Median follow-up was 56.5 months (mean 58.9⫾32.3 months; range 5–180 months). Mitral regurgitation was none or trivial in 167 survivors (65%). Reoperation for valve dysfunction was required in 16 patients (6%); there were 7 late deaths (2.6%). Actuarial, reoperation-free, and event-free survivals at a median follow-up of 56.5 months were 95.2⫾1.5%, 91.6⫾2.2% and 55.9⫾3.5%, respectively; at 15 years, they were 95.2⫾1.5%, 85.9⫾5.9% and 46.7⫾4.7%, respectively. Conclusions: Mitral valve repair in children with chronic rheumatic heart disease is feasible and provides acceptable long-term results. Perspective: For the population described, mitral valve repair appears to offer a durable option for the treatment of nonacute rheumatic mitral valve disease. Because rheumatic mitral valve disease in the US occurs in an older population and typically is associated with significant sclerosis and calcification of the mitral apparatus, these results should not be extrapolated to mitral repair for rheumatic disease in an adult population in the US. DB

Magnetic Resonance Imaging Predictors of Coarctation Severity Nielsen JC, Powell AJ, Gauvreau K, Marcus EN, Prakash A, Geva T. Circulation 2005;111:622– 8. Study Question: What is the accuracy of cardiac magnetic resonance imaging (CMR) to predict hemodynamically significant aortic coarctation (AoCo)?

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Methods: Both CMR and catheterization data were available in 31 patients with native or previously intervened AoCo. Peak AoCo gradient ⬍20 mm Hg was seen in 12 and was ⱖ20 mm Hg in 19 patients (all had normal cardiac output). The CMR was used to anatomically assess the AoCo anatomy, and the smallest aortic cross-sectional area (adjusted for body surface area) was quantified. Additionally, CMRderived flow parameters were calculated in the ascending virgule descending aorta. Results: Receiver operating curve analysis (ROC) was used to identify the most predictive variables. The anatomic variable having the greatest area under the ROC curve was the minimal aortic cross-sectional area indexed to body surface area. Heart-rate-corrected mean deceleration in the descending aorta provided the most additive value to the cross-sectional area. The combination of the two was used to calculate a probability score. Smallest aortic cross-sectional area ⬍56 mm/m2 had a sensitivity and specificity, respectively, of 79% and 83% for predicting AoCo gradient ⱖ20 mm Hg. A probability score ⬎0.38 had a sensitivity and specificity of 95% and 82%, respectively. Conclusions: Using CMR, a combined anatomic and flow characterization can be used as a sensitive and specific marker of hemodynamically significant AoCo. Perspective: Assessing the hemodynamic significance of AoCo has been problematic, with limitations noted to echocardiographic analysis as well as standard physical examination. Direct measurement of the pressure gradient remains the standard for decision making. The CMR accurately identifies the level and severity of anatomic obstruction, but the degree of apparent anatomic obstruction does not always correlate with the hemodynamic abnormality. This study nicely demonstrates that a combination of anatomic and flow assessment by CMR provides a relatively accurate (⫹ and ⫺ predictive value of 90%) method for identifying subjects with a peak trans-coarctation gradient of ⱖ20 mm Hg. It is encouraging to note that the predictive ability of CMR pertains to both native and previously intervened AoCo. WA

(C), reflection coefficient, reflection index and augmentation index were calculated from these data. Results: Compared to the control pts, KD pts had a significantly higher Zc, suggesting increased proximal arterial stiffness. The Zc increases with age, but even taking this into account the Zc was higher for the KD pts, regardless of whether their CALs were still present or had regressed. The C values were significantly lower for KD pts, suggesting increased total arterial stiffness in KD pts. Reflection coefficient, reflection index and augmentation index were all higher for KD pts, indicating increased arterial reflection compared to control pts. Conclusions: There is evidence of abnormal arterial hemodynamics, specifically increased proximal and total arterial stiffness, in pts with KD disease with CALs even when their CALs have regressed. Perspective: Kawasaki disease is well recognized as the most common form of acquired heart disease in children in the developed world. (Rheumatic fever with rheumatic carditis still has that dubious honor in the developing world.) The vasculitis of KD has a predilection for the coronary arteries; timely treatment with intravenous gammaglobulin reduces the risk of aneurysms from ⬃20% to ⬍5%. Even among those pts who do develop CALs, many of these lesions regress by imaging, though there are now several studies, including this one, that document abnormal arterial hemodynamics in the arteries of pts with KD with aneurysms. Because KD is a relatively common disease and affects otherwise normal children, there is a great deal of interest in knowing whether a prior history of KD predisposes these pts to an increased risk of early coronary artery disease. Studies like this one do suggest there is cause for concern, particularly in pts who had documented CALs with the acute illness, and whether or not the CALs appeared to regress. These pts had clear abnormalities on invasive measurement at cath; caths are not done routinely in pts without CALs, and it is still unknown what the arterial hemodynamics and the long-term cardiovascular outcome for KD pts without CALs are likely to be. Thus far, long-term outcome studies in Japan have not found an increased mortality rate in all KD pts (with or without CALs) compared to the general population; however, it will be important to continue to follow this story. Ever since KD was first described in the medical literature in 1967, many KD pts are just now reaching ages where coronary disease might begin to be seen based on other more standard risk factors. SW

Arterial Hemodynamics in Patients After Kawasaki Disease Senzaki H, Chen-Huan C, Ishido H, et al. Circulation 2005;111:2119 –25. Study Question: Is aortic input impedance abnormal in the arteries of patients who have had Kawasaki disease (KD)? Methods: Cardiac catheterization (cath) was performed in 42 patients with KD at least 1 year before; all patients (pts) had coronary artery lesions (CALs) during the acute phase of KD. Of these pts, 26 had persistent CALs while 16 had regressed CALs. Findings at cath were compared to a control group of 36 pts with small subpulmonary, (VSDs). Measurements of aortic flow were made with a flow velocity probe; aortic cross-sectional area was obtained by echocardiography. The characteristic impedance (Zc), compliance

Late Neurodevelopmental Outcome After Repair of Total Anomalous Pulmonary Venous Connection Kirshbam PM, Flynn TZB, Clancy RR, et al. J Thorac Cardiovasc Surg 2005;129:1091–7. Study Question: The study measured neuropsychological function of school-aged survivors of neonatal repair of total anomalous pulmonary venous return (TAPVR). Methods: Patients ⱖ6 years of age with long-term survival following repair of simple TAPVR performed between Jan-

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