What is the clinical utility of routine cardiac catheterization before a Fontan operation?

Utility of Balloon Occlusion Testing in Determining Fontan Suitability Among Patients with Elevated Pulmonary Artery Pressure and Additional Antegrade Pulmonary Blood Flow

In individuals with a single ventricle undergoing evaluation before Fontan surgery, the presence of excessive pulmonary blood flow can contribute to increased pulmonary artery pressure, notably in those who had a Glenn procedure with antegrade pulmonary flow. 28 patients who had previously undergone Glenn anastomosis with antegrade pulmonary blood flow (APBF) and with elevated mean pulmonary artery (mPAP) pressure > 15 mmHg in diagnostic catheter angiography were included in the study. After addressing other anatomical factors that could affect pulmonary artery pressure, APBF was occluded with semi-compliant, Wedge or sizing balloons to measure pulmonary artery pressure accurately. 23 patients (82% of the cohort) advanced to Fontan completion. In this group, median mPAP dropped from 20.5 (IQR 19-22) mmHg to 13 (IQR 12-14) mmHg post-test (p < 0.001). Median PVR post-test was 1.8 (IQR 1.5-2.1) WU m2. SpO2 levels decreased from a median of 88% (IQR 86%-93%) pre-test to 80% (IQR 75%-84%) post-test (p < 0.001). In five patients, elevated mPAP post-test occlusion on diagnostic catheter angiography led to non-completion of Fontan circulation. In this group, median pre- and post-test mPAP were 23 mmHg (IQR 21.5-23.5) and 19 mmHg (IQR 18.5-20), respectively (p = 0.038). Median post-test PVR was 3.8 (IQR 3.6-4.5) WU m2. SpO2 levels decreased from a median of 79% (IQR 76%-81%) pre-test to 77% (IQR 73.5%-80%) post-test (p = 0.039). Our study presents a specialized approach for patients initially deemed unsuitable for Fontan due to elevated pulmonary artery pressures. We were able to successfully complete the Fontan procedure in the majority of these high-risk cases after temporary balloon occlusion test.

Pre-Fontan Assessment Utilizing Combined Cardiac Catheterization and Cardiac MRI: Comparison to the Pre-Fontan Catheterization

Single ventricle patients eligible for Fontan completion undergo pre-Fontan catheterization for hemodynamic and anatomic assessment prior to surgery. Cardiac magnetic resonance imaging may be used to evaluate pre-Fontan anatomy, physiology, and collateral burden. We describe our center's outcomes in patients undergoing pre-Fontan catheterization combined with cardiac magnetic resonance imaging. A retrospective review of patients undergoing pre-Fontan catheterization from 10/2018 to 04/2022 at Texas Children's Hospital was performed. Patients were divided into 2 groups: combined cardiac magnetic resonance imaging and catheterization (combined group) and those who underwent catheterization only (catheterization only group). There were 37 patients in the combined group and 40 in the catheterization only group. Both groups were similar in age and weight. Patients undergoing combined procedures received less contrast, and experienced less in-lab time, fluoroscopy time and catheterization procedure time. Median radiation exposure was lower in the combined procedure group but was not statistically significant. Intubation and total anesthesia times were higher in the combined procedure group. Patients undergoing a combined procedure were less likely to have collateral occlusion performed than in the catheterization only group. Bypass time, intensive care unit length of stay, and chest tube duration were similar in both groups at the time of Fontan completion. Combined pre-Fontan assessment decreases catheterization procedure and fluoroscopy time associated with cardiac catheterization at the expense of longer anesthetic times, and results in similar Fontan outcomes compared to when cardiac catheterization alone is utilized.

Smart Graft Monitoring After the Fontan Operation

The Fontan operation for children with congenital heart disease places them in a physiological state of mildly elevated systemic venous pressure and low-normal cardiac output. Consequently, close follow-up is imperative, yet currently no method is available to obtain Fontan pressures without direct measurements in the cardiac catheterization laboratory while supine and sedated. We hypothesize that by suturing the CardioMEMS sensor device into the Fontan conduit during the standard Fontan operation for a child with single ventricular physiology, clinicians can accurately retrieve Fontan pathway pressure measurements noninvasively during normal physiological states.

Predicting the pressure of the total cavopulmonary connection: clinical testing of a mathematical equation

INTRODUCTION

Some authors advocate the use of a dedicated formula to predict the Fontan pressure starting from pre-Fontan catheterisation data. This paper aims at testing the predictive value of the mentioned formula through a retrospective clinical study.

METHODS AND RESULTS

Pre-Fontan catheterisation data and Fontan pressure measured at the completion were retrospectively collected. Pre-Fontan data were used to calculate the predicted pressure in the Fontan system. The predicted values were compared to the Fontan pressure measured at the Fontan completion and with the needs for fenestration. One hundred twenty-four Fontan patients were retrospectively enrolled (At Fontan: median age 30.73 [24.70-37.20] months, median weight 12.00 [10.98-14.15] kg). Fontan conduit was fenestrated in 78 patients. A poor correlation (r2 = 0.05128) between the measured and predicted data for non-fenestrated patients was observed. In the case of Fontan-predicted pressure <17.59 mmHg, the formula identified a good short-term clinical outcome with a sensitivity of 92%.

CONCLUSION

The proposed formula showed a poor capability in estimating the actual pressure into the Fontan system and in identifying patients needing fenestration. As the pressure into the Fontan system is determined by multiple factors, the tested formula could be an additional data in a multi-parametric approach.

Diagnostic accuracy of low-dose dual-source cardiac computed tomography as compared to surgery in univentricular heart patients

BACKGROUND

To evaluate the ability of low radiation dose dual-source computed tomography (DSCT) to depict the features of morphological univentricular heart and to define accuracy by comparing findings with surgery.

METHODS

Low radiation dose dual-source cardiac computed tomography (CCT) of 33 cases of functional univentricular heart preliminary diagnosis by echocardiography compared with the results of surgery were retrospectively analyzed (aged 1 day to 4 years, median 5 months). The appropriate dose reduction strategies and iterative reconstruction were applied.

RESULTS

Thirty three univentricular heart patients were classified into three types according to Anderson's classification method, including 16 cases (48.5%) univentricular of right ventricular type with rudimentary chamber of left ventricle, 11 cases (33.3%) univentricular of left ventricular type with rudimentary chamber of right ventricle and 6 cases (18.2%) univentricular heart of indeterminate type without rudimentary chamber. The extracardiac malformation such as hypoplastic aortic arch, coronary artery fistula, total anomalous pulmonary venous returns or hypoplastic lung were presented frequently. The overall sensitivity and specification of cardiac CT was 100% compared to the results of surgery. The procedural dose-length product was 18 ± 5 mGy-cm, and unadjusted and adjusted radiation doses were 0.25 and 0.64 mSv, respectively.

CONCLUSION

Cardiac CT can diagnose accurately and be performed with a low radiation exposure in patients with the functional univentricular heart disease. The aorta, pulmonary artery and lung can be evaluated completely and simultaneously as well. Cardiac CT is an effective advanced non-invasive imaging modality to comprehensive evaluation the functional univentricular heart patients, particularly if cardiac MRI poses a high risk or is contraindicated.

Routine Cardiac Catheterization Prior to Fontan Operation: Is It a Necessity?

Prior to the Fontan procedure, patients with single ventricle physiology with Glenn shunt are typically referred for cardiac catheterization to assess hemodynamics and potentially provide interventional measures. Currently, echocardiography provides detailed information which together with other non-invasive imaging such as CT scan and MRI may obviate the need for routine cardiac catheterization prior to the Fontan procedure. In this study, we examine the findings in cardiac catheterization in this population to determine: (a) the accuracy of echocardiography in providing adequate information prior to the Fontan procedure, particularly in identifying those in need of per-catheter intervention, and (b) the percentage of patients requiring interventional procedures during cardiac catheterization. We performed a retrospective chart review of echocardiographic and cardiac catheterization data for patients who underwent pre-Fontan cardiac catheterization at our center in the period from 02/01/2008 to 02/28/2017. We aimed to re-examine the necessity of routine cardiac catheterization in all single ventricle patients. This was performed through examining pre-catheterization echocardiography reports and comparing them to findings of the subsequent cardiac catheterization reports. Echocardiography reports were evaluated for accuracy in identifying significant anatomical or hemodynamic findings, which may impact success of Fontan procedure as well as the ability of echocardiography to predict findings important to know prior to the Fontan procedure. In this cohort of 40 children, 3 patients were found to have significant hemodynamic findings through cardiac catheterization which were not previously known by echocardiography. In addition, 28 out of 40 patients (70%) required interventional procedures to address significant abnormalities (systemic to pulmonary arterial collaterals, pulmonary artery stenosis, aortic arch stenosis, etc.). All cases of aortic arch stenosis were detected by echocardiography, however, all patients who required systemic to pulmonary arterial or left SVC embolization were not detected by echocardiography. Furthermore, echocardiography did not detect the need for branch pulmonary artery stenosis in 50% of cases. Cardiac catheterization appears to be an essential part of patient assessment prior to Fontan completion in patients with single ventricle physiology. This current practice may change in the future if a non-invasive screening tool is found to have high positive and negative predictive values in identifying the subset of patients who require potential intervention in pre-Fontan cardiac catheterization.

Can the Pulmonary Artery Wedge Pressure be Used Reliably as a Surrogate for the Left Atrial Mean Pressure in Pre-Fontan Evaluation?

The correlation between mean pulmonary artery wedge pressure (PAWP) and left atrial mean pressure (LAMP) has been poorly studied in patients with single ventricle (SV) physiology (Bernstein et al. in Pediatr Cardiol 33: 15-20 2012). The aim of this study is to determine if the PAWP can be used safely as a surrogate to the LAMP to calculate the pulmonary vascular resistance (PVR) during the pre-Fontan evaluation. Also, we aimed to understand if the presence of significant systemic-to-pulmonary collaterals (SPCs) is a confounding factor for accurate estimation of the LAMP. From February 2007 to February 2017, forty-one patients were eligible for inclusion in the study. These patients were varied in terms of underlying cardiac malformation. Sex distribution was equal with 20 males and 21 females. Median weight was 11.8 kg, median body surface area was 0.51 m², median age at catheterization was 2 years, and the median age at Glenn surgery was 5 months. We found the left and right PAWP and LAMP correlated strongly and the differences in the measurements were negligible. Similar findings were observed when calculating PVRs using PAWP and LAMP. These findings were more pronounced in the absence of significant SPCs. PAWP and LAMP correlation was still valid in the presence of significant SPCs; however, the correlation among the calculated PVRs was more attenuated.

Advances in pediatric cardiac MRI

PURPOSE OF REVIEW

Spurred by numerous recent technological advances, cardiac MRI (CMR) is now the gold standard for anatomic evaluation, quantitative assessment of chamber size and function, flow quantification, and tissue characterization. This review focuses on recent advances in pediatric and congenital CMR, highlighting recent safety data, and discussing future directions.

RECENT FINDINGS

CMR has become an important component of risk stratification and procedural planning in numerous congenital and pediatric heart diseases. Innovative approaches to image acquisition and reconstruction are leading the way toward fast, high-resolution, three- and four-dimensional datasets for delineation of cardiac anatomy, function, and flow. In addition, techniques for assessing the composition of the myocardium may help elucidate the pathophysiology of late complications, identify patients at risk for heart failure, and assist in the evaluation of therapeutic strategies.

SUMMARY

CMR provides invaluable morphologic, hemodynamic, and functional data that help guide diagnosis, assessment, and management of pediatric and adult congenital heart disease. As imaging techniques advance and data accumulate on the relative and additive value of CMR in patient care, its role in a multimodality approach to the care of this population of patients is becoming clear and is likely to continue to evolve.

Cardiac magnetic resonance versus routine cardiac catheterization before bidirectional Glenn anastomosis: long-term follow-up of a prospective randomized trial

OBJECTIVES

A previously published randomized clinical trial comparing cardiac magnetic resonance (CMR) versus routine catheterization in patients with functional single ventricle before bidirectional Glenn (BDG) operation demonstrated similar short-term post-BDG outcomes. We sought to assess late outcomes in this cohort to ascertain any long-term effects of this evaluation strategy.

METHODS

Retrospective review of enrolled patients through most recent follow-up was performed on all 82 patients in the original cohort, at a median age of 8.8 years.

RESULTS

Of these, 76 (93%) underwent Fontan operation; 2 died before Fontan. Baseline demographics, anatomic factors, and age at BDG did not differ between those randomized to CMR versus catheterization. Although pre-BDG CMR patients were younger at Fontan (2.4 vs 2.7 years; P = .02), baseline weight, body surface area, oxygen saturation, ventricular function, and degree of atrioventricular valve regurgitation were similar. Catheterization before Fontan (n = 76) demonstrated similar hemodynamic parameters including pulmonary vascular resistance and mean pulmonary artery, atrial, and ventricular end-diastolic pressures. CMR patients had comparable rates of transcatheter interventions (71% vs 79%; P = .6), including coil occlusion of systemic-pulmonary collaterals (66% vs 61%; P = .29). At Fontan surgery, short-term complications, hospital length of stay, and the percent meeting a 5-part definition of successful Fontan operation were not different (71% vs 55%; P = .23).

CONCLUSIONS

Pre-BDG CMR and catheterization groups had equivalent clinical and hemodynamic profiles before Fontan and similar post-Fontan outcomes at a median follow-up of 8 years after BDG. For selected patients, a pre-BDG evaluation with CMR is an acceptable alternative to catheterization.

Reduction in postoperative high-density lipoprotein cholesterol levels in children undergoing the Fontan operation

Despite the emerging relevance of high-density lipoprotein (HDL) in the inflammatory cascade and vascular barrier integrity, HDL levels in children undergoing cardiac surgery are unexplored. As a measure of HDL levels, the HDL-cholesterol (HDL-C) in single-ventricle patients was quantified before and after the Fontan operation, and it was determined whether relationships existed between the duration and the type of postoperative pleural effusions. The study prospectively enrolled 12 children undergoing the Fontan operation. Plasma HDL-C levels were measured before and after cardiopulmonary bypass. The outcome variables of interest were the duration and type of chest tube drainage (chylous vs. nonchylous). The Kendall rank correlation coefficient and the Wilcoxon rank sum test were used. There were 11 complete observations. The median preoperative HDL-C level for all the subjects was 30 mg/dl (range, 24-53 mg/dl), and the median postcardiopulmonary bypass level was 21 mg/dl (range, 14-46 mg/dl) (p = 0.004). There was a tendency toward a moderate inverse correlation (-0.42) between the postcardiopulmonary bypass HDL-C level and the duration of chest tube drainage, but the result was not statistically significant (p = 0.07). In the chylous effusion group, the median postcardiopulmonary bypass HDL-C tended to be lower (16 vs. 23 mg/dl; p = 0.09). After the Fontan operation, the plasma HDL-C levels in children are significantly reduced. It is reasonable to conclude that the reduction in HDL-C reflects reduced plasma levels of HDL particles, which may have pertinent implications in postoperative pleural effusions given the antiinflammatory and endothelial barrier functions of HDL.

The role of cardiovascular magnetic resonance in candidates for Fontan operation: proposal of a new algorithm

BACKGROUND

To propose a new diagnostic algorithm for candidates for Fontan and identify those who can skip cardiac catheterization (CC).

METHODS

Forty-four candidates for Fontan (median age 4.8 years, range: 2-29 years) were prospectively evaluated by trans-thoracic echocardiography (TTE), Cardiovascular magnetic resonance (CMR) and CC. Before CC, according to clinical, echo and CMR findings, patients were divided in two groups: Group I comprised 18 patients deemed suitable for Fontan without requiring CC; group II comprised 26 patients indicated for CC either in order to detect more details, or for interventional procedures.

RESULTS

In Group I ("CC not required") no unexpected new information affecting surgical planning was provided by CC. Conversely, in Group II new information was provided by CC in three patients (0 vs 11.5%, p = 0.35) and in six an interventional procedure was performed. During CC, minor complications occurred in one patient from Group I and in three from Group II (6 vs 14%, p = 0.7). Radiation Dose-Area product was similar in the two groups (Median 20 Gycm(2), range: 5-40 vs 26.5 Gycm(2), range: 9-270 p = 0.37). All 18 Group I patients and 19 Group II patients underwent a total cavo-pulmonary anastomosis; in the remaining seven group II patients, four were excluded from Fontan; two are awaiting Fontan; one refused the intervention.

CONCLUSION

In this paper we propose a new diagnostic algorithm in a pre-Fontan setting. An accurate non-invasive evaluation comprising TTE and CMR could select patients who can skip CC.