Han Ki Park

Impact of pressure load caused by right ventricular outflow tract obstruction on right ventricular volume overload in patients with repaired tetralogy of Fallot

OBJECTIVES In correction of tetralogy of Fallot (TOF), surgical strategies to minimize right ventricular outflow tract (RVOT) enlargement have recently been preferred. However, we may be confronted with residual pulmonary stenosis (PS) combined with pulmonary regurgitation (PR), and how the pressure load affects these patients is not evident. METHODS We compared 51 patients with PR and significant PS (PR with PS group) with 87 patients with PR without significant PS (PR group) using echocardiography and cardiac magnetic imaging. We evaluated the differences in parameters derived by magnetic resonance imaging between the 2 groups and the influence of the pressure load on right ventricular (RV) volume and function. RESULTS Although the PR fraction was similar between the 2 groups, the PR with PS group showed significantly smaller RV end-diastolic volume (136.7 ± 26.5 mL/m(2) vs 151.2 ± 34.7 mL/m(2); P = .01), RV end-systolic volume (68.1 ± 23.7 mL/m(2) vs 80.2 ± 27.5 mL/m(2); P = .01), and slightly better RV ejection fraction (51.1% ± 9.8% vs 47.6% ± 8.9%; P = .03) than the PR group. For influence of the pressure load, PR fraction (r = -0.18, P = .03), RV end-diastolic volume (r = -0.25, P = .003), and RV end-systolic volume (r = -0.24, P = .005) were decreased as peak pressure gradient of PS was higher. Linear regression analysis revealed that both PR fraction and peak pressure gradient of PS were independent predictors for RV volume. CONCLUSIONS Our study demonstrated that the RV pressure load prevented RV dilatation from chronic PR without systolic dysfunction. It is suggested that a proper relief of RVOT obstruction with acceptable residual stenosis is more advantageous than aggressive RVOT enlargement in the long-term outcome of repaired TOF.

Congestive hepatopathy after Fontan operation and related factors assessed by transient elastography

OBJECTIVE Congestive hepatopathy after a Fontan operation can have a major effect on long-term morbidity. We evaluated congestive hepatopathy in patients with Fontan circulation using transient elastography to determine which risk factors for hepatopathy are related to liver stiffness (LS). METHODS We evaluated 46 patients with Fontan circulation and 26 with right side heart failure (RHF) and hepatic congestion using laboratory tests, the aspartate aminotransferase-to-platelet ratio index, ultrasonography, and transient elastography. RESULTS The LS value was significantly greater in the Fontan group (21.1±8.0 kPa) than in the RHF group (10.0±9.0 kPa). The total bilirubin and albumin serum levels, white blood cell count, and aspartate aminotransferase to platelet ratio index correlated significantly with LS in the Fontan group. Of the risk factors, age at evaluation (r=0.42, P=.004), age at Fontan completion (r=0.51, P<.001), inferior vena cava diameter (r=0.35, P=.02), and spleen size (r=0.53, P=.002) correlated significantly with LS. Nineteen patients in the Fontan group (41.3%) had abnormal ultrasound findings, and the frequency of abnormal findings increased with increasing LS (P=.002). In the subgroup with the greatest LS value (≥30 kPa), 88.9% had abnormal ultrasound findings and 44.4% liver cirrhosis. Multivariate analysis revealed that age at Fontan procedure completion and total bilirubin were independent risk factors for hepatopathy. CONCLUSIONS The present study revealed that congestive hepatopathy developed in a significant fraction of patients with long-term Fontan circulation and that transient elastography could be an easy and useful method to assess congestive hepatopathy in these patients.

Enhanced Patency and Endothelialization of Small-Caliber Vascular Grafts Fabricated by Coimmobilization of Heparin and Cell-Adhesive Peptides

The clinical utility of a small-caliber vascular graft is still limited, owing to the occlusion of graft by thrombosis and restenosis. A small-caliber vascular graft (diameter, 2.5 mm) fabricated by electrospinning with a polyurethane (PU) elastomer (Pellethane) and biofunctionalized with heparin and two cell-adhesive peptides, GRGDS and YIGSR, was developed for the purpose of preventing the thrombosis and restenosis through antithrombogenic activities and endothelialization. The vascular grafts showed slightly reduced adhesion of platelets and significantly decreased adsorption of fibrinogen. In vitro studies demonstrated that peptide treatment on a vascular graft enhanced the attachment of human umbilical vein endothelial cells (HUVECs), and the presence of heparin and peptides on the graft significantly increased the proliferation of HUVECs. In vivo implantation of heparin/peptides coimmobilized graft (PU-PEG-Hep/G+Y) and PU (control) grafts was performed using an abdominal aorta rabbit model for 60 days followed by angiographic monitoring and explanting for histological analyses. The patency was significantly higher for the modified PU grafts (71.4%) compared to the PU grafts (46.2%) at 9 weeks after implantation. The nontreated PU grafts showed higher levels of α-SMA expression compared to the modified grafts, and for both samples, the proximal and distal regions expressed higher levels compared to the middle region of the grafts. Moreover, immobilization of heparin and peptides and adequate porous structure were found to play important roles in endothelialization and cellular infiltration. Our results strongly encourage that the development of small-caliber vascular grafts is feasible.

Outcomes of biventricular repair for congenitally corrected transposition of the great arteries.

BACKGROUND This study was undertaken to evaluate long-term results of biventricular repairs for congenitally corrected transposition of the great arteries, and to analyze the risk factors that affect mortality and morbidity. METHODS Between 1983 and 2009, 167 patients with congenitally corrected transposition of the great arteries underwent biventricular repairs. The physiologic repairs were performed in 123 patients, and anatomic repairs in 44. Average follow-up was 9.3 +/- 6.6 years. RESULTS Kaplan-Meier estimated survival was 83.3% +/- 0.5% at 25 years in biventricular repair. In anatomic repair, left ventricular training and right ventricular dysfunction had negative impact on survival, but bidirectional cavopulmonary shunt had positive impact on survival. The reoperation-free ratio was 10.1% +/- 7.8% at 22 years after physiologic repair, and 46.2% +/- 12.4% at 15 years after anatomic repair (p = 0.885). Freedom from any arrhythmia was 49.6% +/- 7.5% at 22 years after physiologic repair, and 60.8% +/- 14.8% at 18 years after anatomic repair (p = 0.458). Freedom from systemic atrioventricular valve and ventricular dysfunction as well as tricuspid valve and right ventricular dysfunction was significantly higher in anatomic repair than in physiologic repair. CONCLUSIONS Long-term results of biventricular repair were satisfactory. Patients presenting with right ventricular dysfunction or need for left ventricular training represent a high-risk group of anatomic repair for which selection criteria are particularly important. Late functional outcomes of anatomic repair were excellent compared with physiologic repair. Anatomic repair is the procedure of choice for those patients if both ventricles are adequate or if surgical technique is modified with the help of additional a bidirectional cavopulmonary shunt.

Overexpression of Transforming Growth Factor-β1 in the Valvular Fibrosis of Chronic Rheumatic Heart Disease

For the purpose of determining the pathogenic role of transforming growth factor-β1 (TGF-β1) in the mechanism of chronic rheumatic heart disease, we evaluated the expression of TGF-β1, proliferation of myofibroblasts, and changes in extracellular matrix components including collagen and proteoglycan in 30 rheumatic mitral valves and in 15 control valves. High TGF-β1 expression was identified in 21 cases (70%) of rheumatic mitral valves, whereas only 3 cases (20%) of the control group showed high TGF-β1 expression (p<0.001). Additionally, increased proliferation of myofibroblasts was observed in the rheumatic valves. High TGF-β1 expression positively correlated with the proliferation of myofibroblasts (p=0.004), valvular fibrosis (p<0.001), inflammatory cell infiltration (p=0.004), neovascularization (p=0.007), and calcification (p<0.001) in the valvular leaflets. The ratio of proteoglycan to collagen deposition inversely correlated with TGF-β1 expression in mitral valves (p=0.040). In conclusion, an ongoing inflammatory process, the expression of TGF-β1, and proliferation of myofibroblasts within the valves have a potential role in the valvular fibrosis, calcification, and changes in the extracellular matrix that lead to the scarring sequelae of rheumatic heart disease.

The clinical significance of the atrial subendocardial smooth muscle layer and cardiac myofibroblasts in human atrial tissue with valvular atrial fibrillation.

BACKGROUND The existence of myofibroblasts (MFBs) and the role of subendocardial smooth muscle (SSM) layer of human atrial tissue in atrial fibrillation (AF) have not yet been elucidated. We hypothesized that the SSM layer and MFB play some roles in atrial structural remodeling and maintenance of valvular AF in patients who undergo cardiac surgery. METHODS We analyzed immunohistochemical staining of left atrial (LA) appendage tissues taken from 17 patients with AF and 15 patients remaining in sinus rhythm (SR) who underwent cardiac surgery (male 50.0%, 54.1 ± 14.2 years old, valve surgery 87.5%). SSM was quantified by α-smooth muscle actin (α-SMA) stain excluding vascular structure. MFB was defined as α-SMA+ cells with disorganized Connexin 43-positive gap junctions in Sirius red-positive fibrotic area. RESULTS The SSM layer of atrium was significantly thicker in patients with AF than in those with SR (P=.0091). Patients with SSM layer ≥ 14 μm had a larger LA size (P=.0006) and greater fibrotic area (P=.0094) than those patients whose SSM layer <14 μm. MFBs were found in 7 of 17 (41.2%) patients with AF and 2 of 15 (13.3%) in SR group (P=.0456) in SSM area, colocalized with Periodic Acid-Schiff (PAS) stain-positive glycogen storage cells (95.5%). CONCLUSION SSM layer was closely related to the existence of AF, degrees of atrial remodeling, and fibrosis in patients who underwent open heart surgery. We found that MFB does exist in SSM layer of human atrial tissue co-localized with PAS-positive cells.

Factors associated with progression of right ventricular enlargement and dysfunction after repair of tetralogy of Fallot based on serial cardiac magnetic resonance imaging

OBJECTIVES Although progressive right ventricular (RV) enlargement (RVE) is common in patients with pulmonary regurgitation after tetralogy of Fallot (TOF) repair, the rate of RVE and progression of RV dysfunction varies among patients. The present study aimed to investigate the independent predictors of rapid RVE and RV dysfunction after the repair of TOF, using serial cardiac magnetic resonance imaging (MRI). METHODS The study included consecutive patients who underwent serial cardiac MRI more than twice between January 2005 and March 2015 after the repair of TOF. Patients who underwent surgical pulmonary valve implantation or any transcatheter cardiac intervention between two consecutive MRI assessments were excluded. The study patients were divided into rapid RVE and non-rapid RVE groups according to the rate of RVE. The upper first quartile of the patients was considered to have rapid RV dilatation (defined as rapid RVE group). Remaining patients in other three quartiles were included in the non-rapid RVE group. Additionally, the study patients were divided into rapid right ventricular ejection fraction (RVEF) change and non-rapid RVEF change groups according to the rate of change in the RVEF. The groups were compared, and multiple logistic regression analyses were performed to identify the independent risk factors for rapid RVE and RV dysfunction. RESULTS The study included 116 patients. The mean number of cardiac MRI assessments performed in each patient was 2.8 ± 0.8. The time to the initial MRI assessment after TOF repair was 14.2 ± 10.3 years, and the interval between the initial and last MRI assessments was 4.5 ± 2.2 years. The mean right ventricular end-diastolic volume index (RVEDVi) change rate was 2.7 ± 6.1 ml/m(2)/year. The initial RVEDVi was not different between the rapid RVE and non-rapid RVE groups. Restrictive RV physiology was an independent risk factor for rapid RVE (odds ratio, 3.64; 95% confidence interval, 1.263-10.494; P = 0.02), and a previous palliative shunt procedure was a negative predictor for rapid RVE (odds ratio, 0.08; 95% confidence interval, 0.010-0.778; P = 0.03). We did not find any predictive factors for rapid RV dysfunction. CONCLUSIONS In patients with rapid RV dilatation, restrictive RV physiology might be frequently noted at the initial MRI assessment. Therefore, careful follow-up may be necessary in patients with restrictive RV physiology to determine the optimal timing of pulmonary valve implantation.

Fresh Frozen Plasma in Pump Priming for Congenital Heart Surgery: Evaluation of Effects on Postoperative Coagulation Profiles Using a Fibrinogen Assay and Rotational Thromboelastometry

Purpose In this prospective study, the effects of fresh frozen plasma (FFP) included in pump priming for congenital heart surgery in infants and children on post-bypass coagulation profiles were evaluated. Materials and Methods Either 20% albumin (50-100 mL) or FFP (1-2 units) was added to pump priming for patients randomly allocated into control or treatment groups, respectively. Hematologic assays, including functional fibrinogen level, and rotational thromboelastometry (ROTEM®) were measured before skin incision (baseline), after weaning from cardiopulmonary bypass (CPB) and heparin reversal, and at 24 hours (h) in the intensive care unit (ICU). Results All the baseline measurements were comparable between the control and treatment groups of infants and children. After heparin reversal, however, significantly higher fibrinogen levels and less reduced ROTEM parameters, which reflect clot formation and firmness, were demonstrated in the treatment groups of infants and children. At 24 h in the ICU, hematologic assays and ROTEM measurements were comparable between the control and treatment groups of infants and children. Transfusion requirements, excluding FFP in pump prime, and postoperative bleeding were comparable between the control and treatment groups of infants and children. Conclusion Although clinical benefits were not clearly found, the inclusion of FFP in pump priming for congenital heart surgery in infants and children was shown to improve the hemodilution-related hemostatic dysfunction immediately after weaning from CPB and heparin reversal.

Pulmonary stenosis and pulmonary regurgitation: both ends of the spectrum in residual hemodynamic impairment after tetralogy of Fallot repair

Repair of tetralogy of Fallot (TOF) has shown excellent outcomes. However it leaves varying degrees of residual hemodynamic impairment, with severe pulmonary stenosis (PS) and free pulmonary regurgitation (PR) at both ends of the spectrum. Since the 1980s, studies evaluating late outcomes after TOF repair revealed the adverse impacts of residual chronic PR on RV volume and function; thus, a turnaround of operational strategies has occurred from aggressive RV outflow tract (RVOT) reconstruction for complete relief of RVOT obstruction to conservative RVOT reconstruction for limiting PR. This transformation has raised the question of how much residual PS after conservative RVOT reconstruction is acceptable. Besides, as pulmonary valve replacement (PVR) increases in patients with RV deterioration from residual PR, there is concern regarding when it should be performed. Regarding residual PS, several studies revealed that PS in addition to PR was associated with less PR and a small RV volume. This suggests that PS combined with PR makes RV diastolic property to protect against dilatation through RV hypertrophy and supports conservative RVOT enlargement despite residual PS. Also, several studies have revealed the pre-PVR threshold of RV parameters for the normalization of RV volume and function after PVR, and based on these results, the indications for PVR have been revised. Although there is no established strategy, better understanding of RV mechanics, development of new surgical and interventional techniques, and evidence for the effect of PVR on RV reverse remodeling and its late outcome will aid us to optimize the management of TOF.

Left Atrial Decompression by Percutaneous Left Atrial Venting Cannula Insertion during Venoarterial Extracorporeal Membrane Oxygenation Support.

Patients with venoarterial extracorporeal membrane oxygenation (ECMO) frequently suffer from pulmonary edema due to left ventricular dysfunction that accompanies left heart dilatation, which is caused by left atrial hypertension. The problem can be resolved by left atrium (LA) decompression. We performed a successful percutaneous LA decompression with an atrial septostomy and placement of an LA venting cannula in a 38-month-old child treated with venoarterial ECMO for acute myocarditis.