David T. Balzer

Transcatheter closure of postinfarction ventricular septal defects using the new Amplatzer muscular VSD occluder: Results of a U.S. Registry.

The objective of this study was to assess the immediate and mid‐term results of transcatheter closure of postinfarct muscular ventricular septal defects (VSDs) using the new Amplatzer postinfarct muscular VSD device (PIMVSD). Ventricular septal rupture occurs in 0.2% of myocardial infarcts and remains associated with very high morbidity and mortality. Data were prospectively collected for 18 patients who underwent attempted device closure of postinfarction VSDs between 2000 and 2003. Five patients underwent the closure in the acute phase (within 6 days from the infarct); the remaining patients underwent closure on day 14–95 after the diagnosis of the infarct. Outcome parameters included procedural success, evidence of residual shunts on echocardiography, and occurrence of procedure‐related complications. The procedure was successful in deploying a device across the VSD in 16 of 18 patients. The 30‐day mortality was 28%. Eleven patients are still alive and have been followed up for a median of 332 days. Two patients required a second procedure to close a residual VSD. At the most recent outpatient follow‐up, the VSD was completely closed in two patients, six patients had a trivial or small residual shunt, and two patients had a moderate residual shunt. We conclude that percutaneous device closure of postinfarction VSDs using the Amplatzer PIMVSD occluder appears to be safe and effective. Further trials are required to assess long‐term efficacy and compare the results with those of surgical closure. Catheter Cardiovasc Interv 2004;61:196–201.

Adverse event rates in congenital cardiac catheterization — A multi-center experience†

Objectives: To describe case mix variation among institutions, and report adverse event rates in congenital cardiac catheterization by case type. Background: Reported adverse event rates for patients with congenital heart disease undergoing cardiac catheterization vary considerably, due to non‐comparable standards of data inclusion, and highly variable case mix. Methods: The Congenital Cardiac Catheterization Outcomes Project (C3PO) has been capturing case characteristics and adverse events (AE) for all cardiac catheterizations performed at six pediatric institutions. Validity and completeness of data were independently audited. Results: Between 2/1/07 and 4/30/08, 3855 cases (670 biopsy, 1037 diagnostic, and 2148 interventional) were recorded, median number of cases per site 480 (308 to 1526). General anesthesia was used in 70% of cases (28 to 99%), and 22% of cases (15 to 26%) were non‐electively or emergently performed. Three institutions performed a higher proportion of interventions during a case, 72 to 77% compared to 56 to 58%. The median rate of AE reported per institution was 16%, ranging from 5 to 18%. For interventional cases the median rate of AE reported per institution was 19% (7 to 25%) compared to 10% for diagnostic cases (6 to 16%). The incidence of AE was significantly higher for interventional compared to diagnostic cases (20% vs 10%, p<0.001), as was the incidence of higher severity AE (9% vs 5%, p<0.001). Adverse events in biopsy cases were uncommon. Conclusions: In this multi‐institutional cohort, the incidence of AE is higher among interventional compared to diagnostic cases, and is very low among biopsy cases. Equitable comparisons among institutions will require the development and application of risk adjustment methods.

Resolution of right heart enlargement after closure of secundum atrial septal defect with transcatheter technique

OBJECTIVES The purpose of this study was to prospectively characterize the reduction in right atrial (RA) area and right ventricular (RV) volume after transcatheter closure of atrial septal defect (ASD) and to investigate factors that may predict magnitude of resolution in right heart enlargement. BACKGROUND Secundum ASD can cause volume overload of the right side of the heart with the potential for development of late complications. Little is known about reduction in right heart size after closure of ASD. METHODS Transthoracic echocardiography was performed in 38 patients undergoing transcatheter closure of ASD. The RA area and RV volume were measured prior (n = 38), within 24 hours (n = 37), at 3 to 6 months (n = 24), at 12 months (n = 20) and at 24 months (n = 10) after closure of ASD. Change over time within the study group was assessed and the study group was compared to a control group of 19 patients with structurally normal hearts. RESULTS Indexed RA area decreased from baseline to 3- to 6-month follow-up (p = 0.004) as did indexed RV volume (p < 0.0001). Indexed RV volume was similar to that in the control group at 24 months (p = 0.3); however, indexed RA area remained greater than in the control group (p = 0.006). Decrease in indexed RA area over the first 12 months of follow-up was related to young age at time of closure by regression analysis (r = 0.55, p = 0.013). CONCLUSION Closure of secundum ASD results in decreased indexed RV volume comparable to that in control subjects at 24 months following closure. Indexed RA area remains increased compared to that in control subjects but does decrease over time. Decrease in RA area is inversely proportional to age at time of ASD closure. Long-term follow-up is required to evaluate the clinical impact of persistently increased RA size.

Lung transplantation for pulmonary vascular disease

BACKGROUND Pulmonary hypertension (PHT) is a lethal condition resulting in markedly diminished life expectancy. Continuous prostaglandin I2 infusion has made an important contribution to symptom management, but it is not a panacea. Lung or heart-lung transplantation remains an important treatment option for end-stage PHT patients unresponsive to prostaglandin I2. This study reviews the outcomes after transplantation for PHT in our program. METHODS A retrospective chart review was performed for 100 consecutive patients with either primary PHT (48%) or secondary PHT (52%) transplants since 1989. Living recipients were contacted to confirm health and functional status. RESULTS Fifty-five adult and 45 pediatric patients underwent 51 bilateral lung transplants, 39 single lung transplants, and 10 heart-lung transplants. Mean age was 23.7 years (range, 1.2 months to 54.8 years) and mean pre-transplant New York Heart Association class was 3.2. Pre-transplant hemodynamics revealed a mean right atrial pressure of 9.6+/-5.4 mm Hg and mean pulmonary artery pressure of 64+/-14.4 mm Hg. Hospital mortality was 17% with early death predominantly because of graft failure and infection. With an average follow-up of 5.0 years, 1- and 5-year actuarial survival was 75% and 57%, respectively. Mean pulmonary artery pressure on follow-up catheterization was 22+/-6.0 mm Hg, and mean follow-up New York Heart Association class was 1.3 (p < 0.001 for both compared with pre-transplant). Diagnosis and type of transplant did not confer a significant difference in survival between groups. CONCLUSIONS Whereas lung or heart-lung transplant for PHT is associated with higher early mortality than other pulmonary disease entities, it provides similar long-term outcomes with dramatic improvement in both quality of life and physiologic aspects.

Catheterization for Congenital Heart Disease Adjustment for Risk Method (CHARM)

OBJECTIVES This study sought to develop a method to adjust for case mix complexity in catheterization for congenital heart disease to allow equitable comparisons of adverse event (AE) rates. BACKGROUND The C3PO (Congenital Cardiac Catheterization Project on Outcomes) has been prospectively collecting data using a Web-based data entry tool on all catheterization cases at 8 pediatric institutions since 2007. METHODS A multivariable logistic regression model with high-severity AE outcome was built using a random sample of 75% of cases in the multicenter cohort; the models were assessed in the remaining 25%. Model discrimination was assessed by the C-statistic and calibration with Hosmer-Lemeshow test. The final models were used to calculate standardized AE ratios. RESULTS Between August 2007 and December 2009, 9,362 cases were recorded at 8 pediatric institutions of which high-severity events occurred in 454 cases (5%). Assessment of empirical data yielded 4 independent indicators of hemodynamic vulnerability. Final multivariable models included procedure type risk category (odds ratios [OR] for category: 2 = 2.4, 3 = 4.9, 4 = 7.6, all p < 0.001), number of hemodynamic indicators (OR for 1 indicator = 1.5, ≥2 = 1.8, p = 0.005 and p < 0.001), and age <1 year (OR: 1.3, p = 0.04), C-statistic 0.737, and Hosmer-Lemeshow test p = 0.74. Models performed well in the validation dataset, C-statistic 0.734. Institutional event rates ranged from 1.91% to 7.37% and standardized AE ratios ranged from 0.61 to 1.41. CONCLUSIONS Using CHARM (Catheterization for Congenital Heart Disease Adjustment for Risk Method) to adjust for case mix complexity should allow comparisons of AE among institutions performing catheterization for congenital heart disease.

Biventricular Assist Devices as a Bridge to Heart Transplantation in Small Children

Background— Experience with the use of biventricular assist device (BiVAD) support to bridge small children to heart transplantation is limited. Methods and Results— We used BIVAD support (Berlin EXCOR) in 9 pediatric heart transplant candidates from 4/05 to 7/07. The median patient age was 1.7 years (12 days to 17 years). The median patient weight was 9.4 kg (3 to 38 kg). All children were supported with multiple intravenous inotropes±mechanical ventilation (6) or ECMO (3) before BiVAD implantation. All had significant right ventricular dysfunction. The median pulmonary vascular resistance index (Rpi) was 6.0 WU/m2. Eight patients were successfully bridged to heart transplantation after a median duration of BiVAD support of 35 days (1 to 77 days). One death occurred after 10 days of support from perioperative renal failure in a 3 kg infant. Five patients required at least 1 blood pump change. One patient had a driveline infection requiring treatment. There were no acute neurological complications, no thromboembolic events, and no bleeding complications. In 2 patients with Rpi >10 WU/m2 unresponsive to pulmonary vasodilator therapy, Rpi dropped to 1.4 and 4.6 WU/m2, after 33 and 41 days of support, respectively. All 8 survivors underwent successful heart transplantation. Of 5 patients supported >30 days, 3 developed an extremely elevated (>90%) panel reactive antibody by ELISA that was not confirmed by other methods; none had a positive donor-specific retrospective crossmatch. There was 1 episode of rejection (with hemodynamic compromise) in the 8 transplanted patients. Rpi was normal (<3 WU/m2) without pulmonary vasodilators in all patients within 3 months after transplant. There have been no deaths after transplant with a median follow-up of 19 months. Conclusions— BiVAD support can effectively be used in small children as a bridge to heart transplantation and can be accomplished with low mortality and morbidity. BiVAD support may offer an additional means to reverse extremely elevated pulmonary vascular resistance. Surveillance for HLA antibody sensitization during BiVAD support may be complicated by the development of non-HLA antibodies which may not reflect true HLA presensitization.

Repair of anomalous left main coronary artery arising from the pulmonary artery in infants: long-term impact on the mitral valve

BACKGROUND Infants presenting with anomalous left coronary artery off the pulmonary artery (ALCAPA) are generally in heart failure and often have significant mitral valve regurgitation (MR). Although establishing a dual coronary circulation is the procedure of choice, there remains controversy as to how the mitral valve is handled. METHODS We reviewed our experience with this lesion at St. Louis Childrens Hospital. Over the past 15 years, 17 infants under 18 months of age have undergone repair, with all but one being treated with reimplantation of the left coronary artery into the aorta; the other underwent the Takeuchi procedure (intrapulmonary artery baffle) and was excluded from this evaluation. The average age and weight at operation were 0.5 +/- 0.3 years and 6.1 +/- 1.9 kg, respectively. All presented with varying degrees of heart failure and 9 patients also had either moderate or severe MR. RESULTS There was one early and no late deaths after reimplantation of the left coronary artery. The left ventricular function postrepair improved from a preoperative shortening fraction of 0.19 +/- 0.09 to 0.34 +/- 0.08 (p < 0.01). Moderate or severe MR was present in 2 patients postoperatively, and both developed significant obstruction in the left coronary artery postoperatively as well. Both underwent mitral valve repair and revascularization of the left coronary artery. CONCLUSIONS Excellent results can be obtained in the treatment of this very high-risk group of patients. Mitral valve repair is not generally necessary at the time of the initial operation. However, should MR recur or persist late, it may herald the presence of a coexistent, significant coronary stenosis. Cardiac catheterization should be performed to assess the patency of the left coronary artery before performing mitral valve surgery.

Novel use of the Amplatzer duct occluder to close perivalvar leak involving a prosthetic mitral valve.

Perivalvar leak following atrioventricular valve replacement can result in heart failure or hemolytic anemia. These patients may be poor surgical candidates given a complex clinical condition. We describe transcatheter closure of a perivalvar leak in a 3‐month infant who had undergone left atrioventricular valve replacement with a St. Judes prosthesis. Catheter Cardiovasc Interv 2004;61:548–551.

Procedure-Type Risk Categories for Pediatric and Congenital Cardiac Catheterization

Background— The Congenital Cardiac Catheterization Project on Outcomes (C3PO) was established to develop outcome assessment methods for pediatric catheterization. Methods and Results— Six sites have been recording demographic, procedural and immediate outcome data on all cases, using a web-based system since February 2007. A sample of data was independently audited for validity and data completeness. In 2006, participants categorized 84 procedure types into 6 categories by anticipated risk of an adverse event (AE). Consensus and empirical methods were used to determine final procedure risk categories, based on the outcomes: any AE (level 1 to 5); AE level 3, 4, or 5; and death or life-threatening event (level 4 or 5). The final models were then evaluated for validity in a prospectively collected data set between May 2008 and December 31, 2009. Between February 2007 and April 2008, 3756 cases were recorded, 558 (14.9%) with any AE; 226 (6.0%) level 3, 4, or 5; and 73 (1.9%) level 4 or 5. General estimating equations models using 6 consensus-based risk categories were moderately predictive of AE occurrence (c-statistics: 0.644, 0.664, and 0.707). The participant panel made adjustments based on the collected empirical data supported by clinical judgment. These decisions yielded 4 procedure risk categories; the final models had improved discrimination, with c-statistics of 0.699, 0.725, and 0.765. Similar discrimination was observed in the performance data set (n=7043), with c-statistics of 0.672, 0.708, and 0.721. Conclusions— Procedure-type risk categories are associated with different complication rates in our data set and could be an important variable in risk adjustment models for pediatric catheterization.

Patterns and Potential Value of Cardiac Troponin I Elevations After Pediatric Cardiac Operations

BACKGROUND Perioperative myocardial injury is a major determinant of postoperative cardiac dysfunction for congenital heart disease, but its assessment during this period is difficult. The objective of this study was to determine the suitability of using postoperative serum concentrations of cardiac troponin I (cTnI) for this purpose. METHODS Cardiac troponin I levels were measured serially in the serum of patients undergoing uncomplicated repairs of atrial septal defect (n = 23), ventricular septal defect (n = 16) or tetralogy of Fallot (n = 16). The concentrations were correlated with intraoperative parameters (cardiopulmonary bypass time, aortic cross-clamp time, and cardiac bypass temperature), and postoperative parameters (magnitude of inotropic support, duration of intubation, and postoperative intensive care and hospital stay). RESULTS Postoperative absolute cTnI levels were lesion specific, with a pattern of increase and decrease similar for each lesion. For the total cohort, significant correlations between postoperative cTnI levels at all times (r = 0.43 to 0.83, p < 0.05) until 72 hours were noted for all parameters, except for cardiac bypass temperature. When evaluated as individual procedure groups, no significant relationships were noted in the atrial septal defect group, whereas postoperative cTnI levels were more strongly correlated with all intraoperative and postoperative parameters in the ventricular septal defect group than in the tetralogy of Fallot group. CONCLUSIONS This study suggests that cTnI values immediately after operation reflect the extent of myocardial damage from both incisional injury and intraoperative factors. Cardiac tropinin I levels in the first hours after operation for congenital heart disease are a potentially useful prognostic indicator for difficulty of recovery.