Thomas G. Sharp

Pulmonary hypertension after operations for congenital heart disease: Analysis of risk factors and management

BACKGROUND Management of pulmonary hypertension, a potentially fatal complication of operations to correct congenital heart disease, has evolved through the last 15 years. Monitoring of pulmonary arterial pressure and mixed venous saturation became available, and prophylactic use of alpha-blockers and other vasodilators increased. This study examines risk factors for morbidity and mortality from pulmonary hypertension after operations to correct congenital heart disease and evaluates the impact of management changes on outcomes. METHODS By means of multivariable logistic regression analysis, 880 high-risk patients with congenital heart disease (of 2484 patients undergoing cardiopulmonary bypass between January 1980 and December 1994) were analyzed to determine which were at risk for postoperative pulmonary hypertension and its associated morbidity and mortality. RESULTS Patients with atrioventricular canal (n = 182), truncus arteriosus (n = 47), total anomalous pulmonary venous connection (n = 90), transposition of great arteries (n = 97), hypoplastic left heart syndrome (n = 50), and ventricular septal defect (n = 414) demonstrated a higher risk of postoperative pulmonary hypertension. By multivariable logistic regression, preoperative pulmonary hypertension (p < 0.0001), absence of mixed venous saturation monitoring (p < 0.0001), and absence of prophylactic alpha-blockade (p = 0.0004) significantly increased postoperative pulmonary hypertension. Preoperative pulmonary hypertension (p < 0.001) and absence of prophylactic alpha-blockers (p = 0.0004) were significant risk factors for in-hospital death related to pulmonary hypertension. Repair at older age (except in the case of total anomalous pulmonary venous connection) was a significant risk for postoperative pulmonary hypertension (p = 0.03). CONCLUSION Mixed venous saturation monitoring and alpha-receptor blockade reduced the incidence of pulmonary hypertension after operations for congenital heart disease. Early definitive repair reduced morbidity and mortality from postoperative pulmonary hypertension.

Surgical management of complete atrioventricular septal defects: A twenty-year experience

Creation of a competent left atrioventricular valve is a cornerstone in surgical repair of complete atrioventricular septal defects. To identify risk factors for mortality and failure of left atrioventricular valve repair and to determine the impact of cleft closure on postoperative atrioventricular valve function, we retrospectively analyzed hospital records of 203 patients between January 1974 and January 1995. Overall early mortality was 7.9%. Operative mortality decreased significantly over the period of the study from 19% (4/21) before 1980 to 3% (2/67) after 1990 (p = 0.03). Ten-year survival including operative mortality was 91.3% +/- 0.004% (95% confidence limit): all survivors are in New York Heart Association class I or II. Preoperative atrioventricular valve regurgitation was assessed in 203 patients by angiography or echocardiography and was trivial or mild in 103 (52%), moderate in 82 (41%), and severe in 18 (8%). Left atrioventricular valve cleft was closed in 93% (189/203) but left alone when valve leaflet tissue was inadequate and closure of the cleft might cause significant stenosis. Reoperation for severe postoperative left atrioventricular valve regurgitation was necessary in eight patients, five of whom initially did not have closure of the cleft and three of whom had cleft closure. Six patients had reoperation with annuloplasty and two patients required left atrioventricular valve replacement. Five patients survived reoperation and are currently in New York Heart Association class I or II. On most recent evaluation assessed by angiography or echocardiography (a mean of 59 months after repair), left atrioventricular valve regurgitation was trivial or mild in 137 of the 146 survivors (94%) examined; none had moderate or severe left atrioventricular valve stenosis. By multiple logistic regression analysis, strong risk factors for early death and need for reoperation included postoperative pulmonary hypertensive crisis, immediate postoperative severe left atrioventricular valve regurgitation, and double-orifice left atrioventricular valve. These results indicate that complete atrioventricular septal defects can be repaired with low mortality and good intermediate to long-term results. Routine approximation of the cleft is safe and has a low incidence of reoperation for left atrioventricular valve regurgitation.

Effect of modified ultrafiltration in high-risk patients undergoing operations for congenital heart disease.

BACKGROUND Modified ultrafiltration (MUF) after cardiopulmonary bypass (CPB) in children decreases body water, removes inflammatory mediators, improves hemodynamics, and decreases transfusion requirements. The optimal target population for MUF needs to be defined. This prospective, randomized study attempted to identify the best candidates for MUF during operations for congenital heart disease. METHODS Informed consent was obtained from 100 consecutive patients with complex congenital heart disease undergoing operations with CPB. They were randomized into a control group (n = 50) of conventional ultrafiltration during bypass and an experimental group using dilutional ultrafiltration during bypass and venovenous modified ultrafiltration after bypass (MUF group, n = 50). Postoperative arterial oxygenation, duration of ventilatory support, transfusion requirements, hematocrit, chest tube output, and time to chest tube removal were compared between the groups stratified by age and weight, CPB technique, existence of preoperative pulmonary hypertension, and diagnosis. RESULTS There were no MUF-related complications. In patients with preoperative pulmonary hypertension, MUF significantly improved postoperative oxygenation (445 +/- 129 mm Hg versus control: 307 +/- 113 mm Hg, p = 0.002), shortened ventilatory support (42.9 +/- 29.5 hours versus control: 162.4 +/- 131.2 hours, p = 0.0005), decreased blood transfusion (red blood cells: 16.2 +/- 18.2 mL/kg versus control: 41.4 +/- 27.8 mL/kg, p = 0.01; coagulation factors: 5.3. +/- 6.9 mL/kg versus control: 32.3 +/- 15.5 mL/kg, p = 0.01), and led to earlier chest tube removal. In neonates (< or =30 days), MUF significantly reduced transfusion of coagulation factors (5.4 +/- 5.0 mL/kg versus control: 39.9 +/- 25.8 mL/kg, p = 0.007), and duration of ventilatory support (59.3 +/- 36.2 hours versus 242.1 +/- 143.1 hours, p = 0.0009). In patients with prolonged CPB (>120 minutes), MUF significantly reduced the duration of ventilatory support (44.7 +/- 37.0 hours versus 128.7 +/- 133.4 hours, p = 0.002). No significant differences were observed between MUF and control patients for any parameter in the presence of ventricular septal defect without pulmonary hypertension, tetralogy of Fallot, or aortic stenosis. CONCLUSIONS Modified ultrafiltration after CPB is safe and decreases the need for homologous blood transfusion, the duration of ventilatory support, and chest tube placement in selected patients with complex congenital heart disease. The optimal use of MUF includes patients with preoperative pulmonary hypertension, neonates, and patients who require prolonged CPB.

Dilutional And Modified Ultrafiltration Reduces Pulmonary Hypertension After Operations For Congenital Heart Disease: A Prospective Randomized Study

OBJECTIVE A prospective randomized study was performed to test whether removal of endothelin-1, by ultrafiltration techniques, will reduce pulmonary hypertension after operations for congenital heart disease. METHODS Twenty-four patients with pulmonary hypertension (systolic pulmonary/systemic arterial pressure ratio > 60%) undergoing cardiac operations were randomized into a control group (n = 12) having conventional ultrafiltration and an experimental group (n = 12) undergoing dilutional ultrafiltration during and modified ultrafiltration after cardiopulmonary bypass. Plasma endothelin-1, nitric oxide metabolites, and cyclic guanosine monophosphate were assayed before bypass, 10 minutes into bypass, after bypass, and 0, 3, 6, and 12 hours after the operation in both groups, as well as in the ultrafiltrates and after modified ultrafiltration in the experimental group. Both groups received alpha-blockers (chlorpromazine and/or prazosin) postoperatively using the same guidelines. RESULTS The ultrafiltrates contained significant amounts of endothelin-1 (1.81 +/- 0.86 pg/ml, dilutional, and 6.44 +/- 1.82 pg/ml, modified ultrafiltrate). Endothelin-1 and the pulmonary/systemic pressure ratio were significantly lower in experimental compared with control patients. Nitric oxide metabolites and cyclic guanosine monophosphate increased similarly in both groups for 12 hours after the operation (p = not significant). Three of 12 control patients (25%) but no experimental patients had pulmonary hypertensive crises (p = 0.07). The experimental patients required significantly less ventilatory support (67 +/- 47 hours vs 178 +/- 139 hours for control patients, p = 0.048). CONCLUSIONS Dilutional and modified ultrafiltration reduce endothelin-1 and the pulmonary/systemic pressure ratio postoperatively and may become an important adjunct for preventing pulmonary hypertension after operations for congenital heart disease in high-risk patients.

Surgical management of hypoplastic left heart syndrome

BACKGROUND The treatment of infants with hypoplastic left heart syndrome has been challenging and controversial. METHODS To assess the operative management and intermediate-term outcome, we retrospectively analyzed our surgical experience with 50 newborns with hypoplastic left heart syndrome operated on between January 1989 and June 1995. RESULTS Surgical palliation with a first-stage Norwood operation was offered to 28 patients. The remaining 22 infants were initially listed for heart transplantation, and 15 underwent the operation. Ten of the 15 recipients are alive, and all are in New York Heart Association class I. Seven infants underwent a Norwood procedure after being on the list for transplantation for 12 to 42 days. A total of 34 patients underwent Norwood procedures with one operation aborted because of inoperable anatomy. Two infants who survived the first-stage Norwood operation underwent subsequent heart transplantation and are currently doing well. The 1-year mortality rate for heart transplantation was 18% (3/17) versus 50% (17/34) for the Norwood procedure. Risk factors for early mortality after a Norwood procedure include longer circulatory arrest time (> 50 minutes), preoperative acidosis (pH < 7.20), larger systemic-pulmonary artery shunt (> or = 4 mm), diminutive ascending aorta (< or = 2.0 mm), and anatomic subtype of aortic and mitral atresia. The 1-year survival rate for the Norwood procedure improved from 36% for the patients operated on during 1989 through 1992 to 75% during 1993 to mid-1995 (p = 0.005). Of the 17 survivors of a first-stage Norwood operation, 10 have undergone the second stage (bidirectional Glenn procedure), and 7 have completed a Fontan procedure. Heart transplantation results have also improved, with no deaths since 1992. CONCLUSIONS Both the Norwood procedure and heart transplantation have encouraging early to intermediate results in infants with hypoplastic left heart syndrome. Hypoplastic left heart syndrome should be managed selectively on the basis of cardiac morphology, donor availability, and family wishes. Development of a flexible program involving the use of both procedures may aid in the successful management of infants with hypoplastic left heart syndrome.

Anterior pericardial tracheoplasty for congenital tracheal stenosis: Intermediate to long-term outcomes

BACKGROUND Although several techniques for the treatment of long-segment stenosis of the trachea have been reported, including slide tracheoplasty, rib grafting, and use of a pericardial patch, the optimal repair remains controversial because of a lack of midterm to long-term follow-up data. METHODS To assess the intermediate and long-term outcomes of patients having repair with anterior pericardial tracheoplasty, we reviewed case histories of 12 patients (1984 to present). The median age was 6.7 months (range, 1 to 98 months), and the median weight was 6.0 kg (range, 0.97 to 42 kg). All patients underwent anterior pericardial tracheoplasty through a median sternotomy during partial normothermic cardiopulmonary bypass. An average of 13 tracheal rings (range, five to 23) were divided anteriorly, and a patch of fresh autologous pericardium was used to enlarge the trachea by 1.5 times the predicted diameter for patient age and weight. RESULTS There was one hospital death, and all but 2 patients are long-term survivors. All but 1 current survivor remain asymptomatic, with no bronchoscopic evidence of airway obstruction or granulation on the pericardial patch. All survivors examined have normal tracheal growth and development, with a median follow-up of 5.5 years (range, 1 to 11 years). CONCLUSIONS Anterior pericardial tracheoplasty for congenital tracheal stenosis provides excellent results at intermediate to long-term follow-up.

Determinants of Longer Duration of Endotracheal Intubation After Adult Cardiac Operations

BACKGROUND Poor pulmonary reserve is a risk factor that is used to exclude some patients from major operations. However, the value of routine spirometry in patients undergoing cardiac operations has not been widely evaluated. METHODS The outcomes of 586 consecutive adult patients undergoing cardiac operations were reviewed retrospectively to assess predictors of longer duration of endotracheal intubation. RESULTS By univariate analysis, congestive failure (p < 0.001), cardiomegaly (p = 0.002), recent myocardial infarction (p = 0.039), priority of operation (p = 0.005), previous cardiac operation (p < 0.001), and renal insufficiency (p = 0.002) increased the risk of longer endotracheal intubation. Spirometry (forced vital capacity, forced expiratory volume at 1 second, the ratio of forced expiratory volume at 1 second to forced vital capacity) did not correlate with longer endotracheal intubation. Perioperative complications, such as myocardial infarction (p < 0.001), coma, reexploration for bleeding, and reduced cardiac output (p < 0.001 each), correlated with longer duration of intubation. By multiple regression, priority of operation (p = 0.03), congestive failure (p = 0.02), and previous cardiac operation (p = 0.005) among preoperative risks and bleeding, reduced cardiac output, stroke, coma, and MB fraction of creatine kinase released postoperatively (p < 0.001 each) predicted longer duration of endotracheal intubation. CONCLUSIONS Postoperative cardiac function and the occurrence of complications are more significant than preoperative pulmonary function in determining the duration of endotracheal intubation after cardiac operation. Routine spirometry is probably unnecessary for most adult cardiac patients.

Donor cardiac troponin T: a marker to predict heart transplant rejection

BACKGROUND Noninvasive methodologies have shown poor sensitivity in predicting rejection when compared to serial endomyocardial biopsies. We studied the potential role of donor blood troponin T (Tn-T) as a marker for predicting heart transplant rejection. METHODS Blood cardiac Tn-T was measured from 16 heart donors. Transplant rejection and cardiac function in the recipients were monitored for 1 year. RESULTS When data were analyzed based on donor blood Tn-T levels, 6 patients who received hearts from donors with low Tn-T (<0.45+/-0.1 ng/mL) showed no rejection, and patients whose hearts came from donors with higher Tn-T (6.01+/-0.81 ng/mL) developed episodes of high-grade rejection (3A) within 38.5+/-2.1 days after transplantation. Eight patients who received hearts from donors with intermediate levels of Tn-T (3.57+/-0.55 ng/mL) showed mild rejection (grade 1). All recipients had qualitatively normal left ventricular systolic function by serial echocardiography. The mean donor ischemic time was 169+/-47 minutes. CONCLUSIONS The quality of the donor heart is an important prognostic factor in heart transplantation. It may be possible to identify severely damaged donor organs before transplantation and avoid their use or to develop more aggressive strategies for reducing recurrent acute rejection episodes in high-risk patients.

Evolution of the Fontan procedure in a single center

BACKGROUND Surgical approaches to single ventricle variants include staged, fenestrated, and completed Fontan operations. This study compares outcomes with these modifications of the Fontan operation at a single center. METHODS Preoperative risk factors and operative results were analyzed by multivariate techniques in 129 patients undergoing modified Fontan operations since March 1988. RESULTS Overall early and late mortality was 5.4% and 0.8%, respectively. Before 1993, completed Fontan operation using right atrial to pulmonary artery anastomosis without fenestration was performed in the majority of patients (44 of 58; 76%). During this period, 10 of 17 patients at high risk had completed Fontan with three takedowns. In 1994, the staged hemi-Fontan and modified Fontan with a lateral tunnel anastomosis and with or without small fenestration (2.5 to 4 mm) were introduced. The majority of patients at high risk during this period underwent hemi-Fontan followed by fenestrated Fontan with no takedowns. Late atrial dysrhythmias occurred in 6 patients (4.7%), generally with larger fenestrations or right atrial to pulmonary anastomoses. Three patients (2.3%) had a stroke, 2 with large (> or = 4 mm) fenestrations. Of 38 fenestrations, 32 (84%) closed spontaneously by 1 year. No protein-losing enteropathy occurred. Most patients (118 of 121) were in New York Heart Association class I/II 4.5 years postoperatively. By multivariate analysis, only Downs syndrome (p < 0.001) predicted early mortality, whereas both Downs syndrome and a systemic right ventricle decreased late survival (p < 0.006). CONCLUSIONS Proper selection of patients for modifications of the Fontan procedure resulted in excellent early and late survival with a low incidence of atrial dysrhythmia and stroke. Midterm functional outcomes were excellent.

Valved bovine jugular venous conduits for right ventricular to pulmonary artery reconstruction

Various valved and nonvalved external right ventricle (RV) to pulmonary artery (PA) conduits have been used to palliate congenital heart anomalies. The ideal conduit has not been found. Reasons for conduit failures include stenosis, thrombosis, calcification of the valve or graft wall, and development of an obstructive peel. We evaluated valved and nonvalved conduits constructed from a glutaraldehyde preserved segment of bovine jugular vein. Bovine jugular conduits (n = 31), 10-13 mm in diameter, were implanted into weight-matched adult mongrel dogs using a standard closed heart technique. Valved conduits (VC, n = 17) were stented at the valve annulus with a Gore-Tex ring, whereas the nonvalved conduits (NC, n = 14) were stented at their midpoint. The proximal PA was tightly banded to 3 mm with a ligature. Cardiac output (CO) and hemodynamic gradients were measured at the time of insertion and 8 months postoperatively. Pulmonary artery angiograms were used to assess bovine jugular conduit regurgitation. All xenografts were evaluated by gross and histologic exam. Two dogs had conduits placed but died for reasons unrelated to the conduit before evaluation. Valved conduit leaflets showed thickening, insignificant thrombus deposition in the base of one or more cusps, and a mild degree of regurgitation as assessed by angiograms. Examination of the NC showed mild conduit thickening and a moderate-to-severe degree of regurgitation as assessed by angiograms. There was a significant difference observed in pulmonary outflow gradients between the VC (11 +/- 2 mm Hg) and NC (17 +/- 2 mm Hg) (p < 0.05), although neither group developed a hemodynamically significant gradient. On gross examination, VC ventricles displayed significantly less evidence of volume and pressure overload compared with the NC ventricle. Valved conduits demonstrated significantly less obstruction and regurgitation. The potential clinical advantages of bovine jugular conduits are their availability, potential durability evidenced by lack of early calcification, and the advantage of not requiring a proximal extension for the RV anastomosis. The presence of a durable and functional xenograft valve in valved conduits may prevent postoperative sequelae in some patients.