Cheul Lee

Outcomes of Pulmonary Valve Replacement in 170 Patients With Chronic Pulmonary Regurgitation After Relief of Right Ventricular Outflow Tract Obstruction: Implications for Optimal Timing of Pulmonary Valve Replacement

OBJECTIVES The objectives of this study were to evaluate outcomes of pulmonary valve replacement (PVR) in patients with chronic pulmonary regurgitation (PR) and to better define the optimal timing of PVR. BACKGROUND Although PVR is effective in reducing right ventricular (RV) volume overload in patients with chronic PR, the optimal timing of PVR is not well defined. METHODS A total of 170 patients who underwent PVR between January 1998 and March 2011 for chronic PR were retrospectively analyzed. To define the optimal timing of PVR, pre-operative and post-operative cardiac magnetic resonance imaging (MRI) data (n = 67) were analyzed. RESULTS The median age at the time of PVR was 16.7 years. Follow-up completeness was 95%, and the median follow-up duration was 5.9 years. Overall and event-free survival at 10 years was 98% and 70%, respectively. Post-operative MRI showed significant reduction in RV volumes and significant improvement in biventricular function. Receiver-operating characteristic curve analysis revealed a cutoff value of 168 ml/m(2) for non-normalization of RV end-diastolic volume index (EDVI) and 80 ml/m(2) for RV end-systolic volume index (ESVI). Cutoff values for optimal outcome (normalized RV volumes and function) were 163 ml/m(2) for RV EDVI and 80 ml/m(2) for RV ESVI. Higher pre-operative RV ESVI was identified as a sole independent risk factor for suboptimal outcome. CONCLUSIONS Midterm outcomes of PVR in patients with chronic PR were acceptable. PVR should be considered before RV EDVI exceeds 163 ml/m(2) or RV ESVI exceeds 80 ml/m(2), with more attention to RV ESVI.

Off-pump coronary artery bypass may decrease the patency of saphenous vein grafts

BACKGROUND There is concern that a hypercoagulable status is caused after coronary artery bypass grafting without cardiopulmonary bypass (off-pump coronary artery bypass grafting, or OPCAB) and may potentially endanger the patency of the anastomosis. The aims of this study were: (1) to compare 1-year graft patency after OPCAB with that of conventional coronary artery bypass grafting (CABG) and that of on-pump beating CABG; and (2) to demonstrate any differences in patency of various conduits among the three groups. METHODS We analyzed the results of 122 consecutive OPCAB cases (group 1) compared with those of 65 consecutive conventional CABG cases (group II) and those of 19 consecutive on-pump beating CABG cases (group III). In group I, coronary angiography (CAG) was performed immediately postoperatively and 1 year after surgery. In groups II and III, CAG was performed 1 year after surgery. Graft patency was graded as grade A (excellent), grade B (fair), or grade O (occluded). RESULTS The average number of distal anastomoses in groups I, II, and III were 3.1 +/- 1.1, 3.7 +/- 0.9, and 3.6 +/- 0.9, respectively. In group I, postoperative CAG was performed in 92% of patients (112/122) before discharge. The patency rate (grade A + B) was 96.4% (162/168) for arterial grafts, and 85.6% (160/187) for saphenous vein grafts (SVG). One-year follow-up CAG was performed in 74% of patients (90/122). The patency rate was 97.8% (132/135) for arterial grafts and 67.9% (106/156) for SVG. In group II, 1-year follow-up CAG was performed in 65% of patients (42/65). The patency rate (grade A + B) was 93.5% (43/46) for arterial grafts and 88.3% (98/111) for SVG. In group III, 1-year follow-up CAG was performed in 89% of patients (17/19). The patency rate (grade A + B) was 100% (19/19) for arterial grafts and 86.8% (33/38) for SVG. CONCLUSIONS Our results demonstrate that the patency rate ot SVG after OPCAB was significantly lower than that of arterial grafts in the early postoperative CAG (p < 0.001), and was also significantly lower than those of SVG of group II (p < 0.001) and group III (p < 0.01) in the postoperative 1-year CAG, although there was no significant difference in 1-year patency of arterial grafts among the three groups. Our data suggest that a specific perioperative anticoagulant therapy may be advisable in patients undergoing OPCAB with SVG.

Inclusion of Hepatic Venous Drainage in Patients with Pulmonary Arteriovenous Fistulas

BACKGROUND It is well known that hepatic vein (HV) inclusion can ameliorate cyanosis in patients with pulmonary arteriovenous fistulas (PAVFs) during the sequence of Fontan type repair. Previously, we reported that most patients with bidirectional cavopulmonary shunt (BCPS) have clinical or subclinical evidence of a right to left shunt through PAVFs. METHODS We studied 33 patients who already had clinical and subclinical PAVFs after BCPS. All patients have taken Fontan completion with HV inclusion. The state of PAVFs was reevaluated by pulmonary angiogram, contrast echocardiography, and lung scintigraphy 7.7 +/- 2.4 years after HV inclusion. RESULTS After Fontan completion, the mean oxygen saturation increased from 80.2 +/- 7.4% to 91.5 +/- 9.8% in the entire cohort. Moreover, the amount of right-to-left shunting through the PAVFs, measured by lung scintigraphy, was decreased from a mean of 23.8 +/- 15.1 to 13.0 +/- 8.2%. The degree of severity, for most patients, was decreased as demonstrated by contrast echocardiography. However, 5 patients (16.7%) showed persistent PAVFs, even after the HV inclusion. They all had left isomerism with azygous continuation of the IVC and the conduit was positioned on the contralateral side to the SVC with azygous drainage. CONCLUSIONS Most PAVFs regressed after Fontan completion. Left isomerism with azygous continuation of the IVC had risk for persistent PAVFs when the HV conduit was positioned at the contralateral side to the SVC receiving the azygous drainage. Therefore, appropriate design avoiding unilateral streaming of HV flow should be considered for HV inclusion surgery.

High-concentration glutaraldehyde fixation of bovine pericardium in organic solvent and post-fixation glycine treatment: in vitro material assessment and in vivo anticalcification effect

OBJECTIVE Glutaraldehdye (GA)-fixed xenografts are widely used in cardiovascular surgery. The objective of this study was to evaluate the anticalcification effect of glycine treatment and high-concentration GA fixation in organic solvent on GA-fixed bovine pericardium, and to evaluate the possible synergistic effect of combined treatment. METHODS Bovine pericardial tissues were divided into four groups according to the methods of treatment. Group 1 consisted of tissues fixed with 0.5% GA (control), group 2 fixed with 0.5% GA and post-treated with glycine, group 3 fixed with 2% GA in organic solvent (65% ethanol+5% octanol), and group 4 fixed with 2% GA in organic solvent and post-treated with glycine. The material characteristics of the treated tissues were assessed by amino acid analysis, thermal stability test, uniaxial mechanical test and light microscopy. The tissues were subcutaneously implanted into 4-week-old rats for 8 weeks, and the calcium contents of the explanted tissues were measured. RESULTS Differently treated tissues resulted in no significant alterations in material characteristics and morphology as assessed by amino acid analysis, thermal stability test, uniaxial mechanical test, and light microscopy. Median calcium contents of groups 1, 2, 3, and 4 were 80.5 μg mg(-1), 1.0 μg mg(-1), 0.5 μg mg(-1) and 1.7 μg mg(-1), respectively. The calcium contents of groups 2, 3 and 4 were all significantly lower than that of group 1 (p < 0.05). CONCLUSIONS Post-fixation treatment with glycine, high-concentration GA fixation in organic solvent and combined treatment of these all strongly prevented calcification of GA-fixed bovine pericardium in rat subcutaneous implantation model.

Factors associated with right ventricular dilatation and dysfunction in patients with chronic pulmonary regurgitation after repair of tetralogy of Fallot: Analysis of magnetic resonance imaging data from 218 patients

OBJECTIVE The aim of the present study was to identify the factors associated with right ventricular (RV) dilatation and dysfunction in patients with chronic pulmonary regurgitation (PR) after repair of tetralogy of Fallot. METHODS From April 2002 to June 2013, 218 patients with repaired tetralogy of Fallot underwent magnetic resonance imaging; 165 (76%) underwent transannular repair and 36 (17%) underwent nontransannular repair. Linear regression analyses were used to identify the predictors for RV end-diastolic volume index (EDVI), end-systolic volume index (ESVI), and ejection fraction. RESULTS On univariable analysis, male sex, ventricular septal defect (VSD) closure through the right ventricle, larger pulmonary artery index, and greater PR fraction were associated with greater RV volume indexes. Multivariable analyses identified male sex (β = 17.55, P < .001 for RV EDVI; β = 14.08, P = .001 for RV ESVI), VSD closure through RV (β = 8.49, P = .048 for RV ESVI), longer interval since repair (β = 1.29, P = .014 for RV EDVI), and greater PR fraction (β = 1.92, P < .001 for RV EDVI; β = 1.38, P < .001 for RV ESVI) as independent predictors for greater RV volume indexes. On univariable analysis, male sex, VSD closure through the right ventricle, and greater PR fraction were associated with a lower RV ejection fraction. Multivariable analysis identified male sex (β = -3.10, P = .018), VSD closure through the right ventricle (β = -3.05, P = .020), and greater PR fraction (β = -0.27, P < .001) as independent predictors for a lower RV ejection fraction. CONCLUSIONS Male sex, VSD closure through the right ventricle, longer interval since repair, and greater PR fraction were independent predictors of RV dilatation after tetralogy of Fallot repair. Male sex, VSD closure through the right ventricle, and greater PR fraction were also independent predictors of RV dysfunction.

Permanent Epicardial Pacing in Pediatric Patients: 12-Year Experience at a Single Center

BACKGROUND Permanent cardiac pacing is not often done in children, and when done is usually accomplished through epicardial pacing. We reviewed a 12-year experience with the implantation of epicardial pacemakers by our clinical group. METHODS Fifty-three patients who underwent their first implantation of an epicardial pacemaker before the age of 18 years and between 1997 and 2009 were included in our study. The mean age of the patients at the time of first pacemaker implantation was 5.7±4.8 years. Indications for pacemaker implantation included postoperative or congenital atrioventricular block and sinus node dysfunction. The patients underwent 105 operations for the replacement of pacemaker pulse generators and 75 operations for the replacement of pacemaker leads. The most commonly used generator mode was the rate-responsive accelerometer-based (DDDR) mode, which was used in 40.9% of the patients. We used more non-steroid-eluting leads (70.1%) than steroid-eluting leads (29.1%). RESULTS The overall duration of follow-up in the study was 8.0±4.5 years (range, 2.1 months to approximately 17.0 years). Freedom from the need for generator replacement was 98.0%, 60.7%, and 11.1% at 1, 5, and 8 years, respectively. A tendency toward early generator exhaustion was observed among younger patients (p=0.058). The generator mode used for pacing did not significantly affect generator longevity. Freedom from the need for lead replacement was 98.3%, 83.8%, and 63.6% at 1, 5, and 10 years, respectively. The mean longevity of the leads used in the study was 10.8±0.8 years. Neither patient age at the time of lead implantation nor type of lead significantly affected lead longevity. CONCLUSIONS Lead longevity was sufficiently long and did not vary significantly according to type of lead. Generator longevity was not affected by lead type, generator mode, or patient age at the time of pacemaker implantation.

Long-term results after mitral valve repair in children

OBJECTIVE We analysed the long-term results of mitral valve (MV) repair in children. METHODS We reviewed clinical records of 139 children (<18 years) who underwent MV repair between 1988 and 2007. Patients with atrioventricular septal defect, single ventricle or atrioventricular discordance were excluded. Median age was 2.3 years (2 months to 17.6 years), and 47 children (34%) were infants. Mitral regurgitation (MR) was predominant in 125 patients (90%), and 91 (73%) of these showed MR grade > or = 3. Mitral stenosis (MS) was predominant in 14 patients (10%), and median mean pressure gradient across the MV was 9.0 mmHg (0-20 mmHg). Associated cardiac lesions were present in 111 patients (80%) and were addressed concurrently in 105 patients. Various surgical techniques were used according to the functional and pathologic findings of MV. RESULTS There was no early death. Median follow-up was 8 years (2 months to 20 years, 78% complete). Twenty-six patients required 29 MV re-operations, and 11 of these required MV replacements. At 15 years, freedom from MV re-operation and MV replacement was 77% and 90%, respectively. Diagnosis of MS and MV status on discharge (MR grade > or =3 or MS gradient > or =10 mmHg) were significant risk factors for re-operation. There were three late deaths, and the overall survival was 97% at 15 years. Among 122 survivors with MR, 102 patients (84%) underwent echocardiography during follow-up. The degree of MR decreased significantly and only five patients showed MR grade 3. Among 14 survivors with MS, eight patients (57%) underwent echocardiography during follow-up. The degree of MS decreased significantly and median MS gradient was 2.8 mmHg (0-10 mmHg). All survivors remain in the NYHA class I or II. CONCLUSIONS MV repair in children showed excellent survival, acceptable re-operation rate and satisfactory valve function at long-term follow-up. Residual MV dysfunction was a significant risk factor for re-operation, but re-repair was successful in more than half of the patients who underwent re-operation.

Bicuspid pulmonary valve implantation using polytetrafluoroethylene membrane: early results and assessment of the valve function by magnetic resonance imaging

OBJECTIVES The durability of bioprosthetic valves in the pulmonary position is suboptimal. The objectives of this study were to evaluate the early results of polytetrafluoroethylene (PTFE) bicuspid pulmonary valve (PV) implantation and to better define the function of this valve by magnetic resonance imaging (MRI). METHODS Fifty-six patients who underwent PTFE bicuspid PV implantation between June 2009 and August 2011 were retrospectively analysed. The median age was 17.5 years and median valve size was 26 mm. Fundamental diagnoses were tetralogy of Fallot (n = 38), pulmonary atresia with ventricular septal defect (n = 8), double outlet right ventricle (n = 7) and absent PV syndrome (n = 3). Thirty-two patients with pulmonary regurgitation (PR) underwent MRI preoperatively and 22 of them underwent follow-up MRI at a median of 6.7 months postoperatively. RESULTS There was one early death. Postoperative echocardiography (n = 53) showed no or trivial PR in 49 patients and mild PR in 4. Median follow-up duration was 15.2 months. There was no late death or reoperation. Follow-up echocardiography (n = 41) performed at a median of 7.5 months postoperatively showed no or trivial PR in 33 patients and mild PR in 8 patients. Follow-up MRI showed a significant reduction in right ventricular volumes and improvement in biventricular function. The median PR fraction of this valve was 10%. CONCLUSIONS Early results of bicuspid PV implantation using PTFE membrane were satisfactory. PTFE bicuspid PV demonstrated excellent performance for the short term as evidenced by echocardiography and MRI. Long-term follow-up is mandatory to determine the durability of this valve.

Surgical Management of Pulmonary Atresia With Ventricular Septal Defect: Early Total Correction Versus Shunt

BACKGROUND We changed our surgical strategy for pulmonary atresia with ventricular septal defect from shunt operation to early total correction as an initial procedure since 2004. The objective of this study was to compare the surgical outcomes of shunt and early total correction. METHODS From 1997 to 2008, 47 patients with pulmonary atresia with ventricular septal defect and no major aortopulmonary collateral arteries who underwent surgical correction were enrolled in this retrospective study. Twenty-nine patients underwent palliative shunt operation (group S) and 18 patients underwent early total correction (group T). The patients in group T were younger than that of group S (23.2±12.6 vs 40.1±23.3 days; p=0.008). RESULTS There were 3 operative mortalities in group S and 1 operative mortality in group T. Four interstage deaths in group S and 1 late death in group T occurred. There was no difference in the overall survival rate between the 2 groups (p=0.3). The reoperation rate was higher in group S (p<0.0001) and the reintervention rate was higher in group T (p=0.006). The ventilator support time (5.5±5.1 vs 4.2±5.6 days; p=0.016) and intensive care unit stay (20.3±25.5 vs 15.5±16.0 days; p=0.233) were longer in group T. The preoperative age, body weight, and pulmonary artery size were not associated with the prolonged ventilator support time in group T. The patients who had received preoperative ventilator care showed tendency of prolonged postoperative ventilator support time (p=0.004). CONCLUSIONS The midterm results of early total correction for pulmonary atresia with ventricular septal defect are acceptable. Despite a difficult postoperative course, there was no difference in the mortality compared with shunt operation. Although the reintervention rate was higher in the early total correction group, we were able to avoid interstage mortalities that occurred in the shunt group, and we reduced the reoperation rate in the early total correction group.

Immune response to bovine pericardium implanted into α1,3-galactosyltransferase knockout mice: feasibility as an animal model for testing efficacy of anticalcification treatments of xenografts

OBJECTIVES Glutaraldehyde (GA)-fixed xenografts are prone to calcification after implantation in humans and there is evidence that immune reaction to the Galα1,3-Galβ1,4GlcNAc-R (α-Gal) antigen may play a part in this process. The objectives of this study were to evaluate the immune response of α1,3-galactosyltransferase knockout (α-Gal KO) mice to bovine pericardium and to evaluate the effect of various anticalcification treatments on bovine pericardium using mouse subcutaneous implantation model. METHODS Bovine pericardial tissues were divided into eight groups according to the method of anticalcification treatments. Prepared tissues were subcutaneously implanted into the α-Gal KO and wild-type mice for 2 months, and anti-α-Gal antibodies were measured at 2 weeks and 2 months after implantation. Explanted tissues were examined by immunohistochemistry and calcium contents of the explanted tissues were measured. RESULTS Titres of IgM and IgG antibodies in the α-Gal KO mice increased significantly according to the duration of implantation, whereas titres of IgM and IgG antibodies in the wild-type mice increased until 2 weeks after implantation without further increase thereafter. Titres of IgG antibodies measured at 2 months after implantation were significantly higher in the α-Gal KO mice than in the wild-type mice. Immunohistochemistry revealed macrophages surrounding the pericardial tissues irrespective of the mouse type into which the tissues implanted, whereas T-cells could only be observed in the tissues implanted into the α-Gal KO mice. Except the high-concentration GA-treated group, calcium contents of anticalcification-treated groups were all significantly lower or tended to be lower than that of the control group, irrespective of the mouse type. Calcium contents of the control group were significantly higher in the α-Gal KO mice than in the wild-type mice. CONCLUSIONS Bovine pericardium implanted into the α-Gal KO mice caused significant increase in anti-α-Gal antibodies, showed some histologic evidences of chronic rejection and revealed a potential toward more calcification. These findings suggest a possible role of immune response in calcification of xenografts. High-concentration GA fixation alone did not prove to be an effective anticalcification treatment in mouse subcutaneous implantation model. α-Gal KO mouse subcutaneous implantation model might be a feasible animal model for testing efficacy of anticalcification treatments incorporating immunologic approach.