William E. Hellenbrand

Thromboembolic Complications After Fontan Operations

BACKGROUNDnDespite the increasing recognition of thromboembolic complications of the Fontan procedure, data characterizing such events are limited. The total cavopulmonary connection is believed to be less prone to this complication than other modifications of Fontan operations. We examined our experience with thromboembolism after Fontan operations to better characterize these events and their relation to the type of Fontan operation performed.nnnMETHODS AND RESULTSnWe retrospectively identified 70 patients who underwent a Fontan operation between January 1978 and March 1994. Patients were divided into three groups: (1) total cavopulmonary connection, (2) atriopulmonary connection, and (3) conduit interposition. Fourteen patients (20%) developed a thromboembolic complication during a mean (+/- SD) follow-up of 5.2 +/- 4.7 years. The rate of thrombosis was similar in each group. The time from Fontan operation to thrombosis averaged 6.1 +/- 5.0 years. The overall rate of thromboembolic events was 3.9 per 100 patient-years. Twelve of the 14 thrombi were located within the venous circulation, 1 was in the left ventricle, and the location of 1 was undetermined. Six of the patients (43%) were asymptomatic, 3 (21%) presented with cerebrovascular events, and 5 (36%) presented with other symptoms. Thromboembolic events occurred from the perioperative period to 15 years after surgery.nnnCONCLUSIONSnThromboembolic complications occur frequently after the Fontan operation and its modifications and are a cause of significant morbidity. The time of presentation varies greatly. The rate of thrombosis appears to be similar in all modifications of the Fontan operation.

Transesophageal echocardiographic guidance of transcatheter closure of atrial septal defect

Transcatheter closure of atrial septal defect (ASD) was accomplished in 10 of 11 patients aged 13 months to 46 years (weight range 11 to 77 kg). Transesophageal echocardiography (TEE) was used simultaneously with fluoroscopic imaging in 4 of these patients aged 4.5 to 46 years (weight range 19 to 77 kg). TEE was used to ascertain defect size, position and number of defects and to ascertain appropriate seating of the defect occluder within the atrial defect. In 2 patients TEE-assisted transcatheter ASD closure was accomplished after previous attempts at transcatheter ASD closure, unaided by TEE, had been unsuccessful. The only unsuccessful ASD closure procedure occurred in the smallest patient in the series (an 11-kg 13-month-old), a child who was too small to undergo TEE using our 11-mm diameter endoscopic probe. The concomitant use of TEE with fluoroscopic imaging provides information that is unique and complementary and may improve the efficacy and safety of the transcatheter technique for ASD closure. The recent availability of a 7-mm diameter TEE probe will extend the use of TEE into the infant age group and may decrease the discomfort and potential morbidity of TEE in older patients.

Implantation of balloon‐expandable stents for coarctation of the aorta: Implantation data and short‐term results

We report the immediate results and the short-term follow-up in a group of selected patients with coarctation of the aorta who underwent endovascular stent implantation. Balloon-expandable stents were implanted in 6 patients (mean age 19.8 +/- 5.1 years) with coarctation of the aorta (4 recurrent and 2 native) who underwent a total of 7 procedures (6 implantation and 1 further expansion). The systolic peak pressure gradient was decreased from 36.7 +/- 16.9 to 13.3 +/- 23.2 mm Hg (P < 0.005). There was a 66% increase in the mean coarctation diameter from 9.3 +/- 1.7 to 15.6 +/- 3.1 mm (P = 0.001) with the ratio of the coarctation to descending aorta diameter, measured at the level of the diaphragm, increasing from 0.49 +/- 0.1 to 0.81 +/- 0.2 (P < 0.005). The dilatation was successful in expanding the stent to an acceptable diameter in 5 of 6 patients. One patient underwent successful further expansion of a stent implanted 22 months previously. There were no immediate complications during balloon expansion and stent implantation. One patient suffered a femoral arterial bleed requiring surgical repair. There was one unrelated death. All patients were hypertensive (systolic blood pressure > 140 mm Hg) prior to stent implantation. At mean follow-up of 8 months, 3 patients are normotensive. There was no recurrence of coarctation, aortic dissection, or aneurysm formation in the patients in whom stent implantation was successful. These findings indicate that balloon-expandable stent implantation for coarctation of the aorta in selected patients is a safe and effective alternative approach for relieving the obstruction with a low complication rate and no recoarctation at short-term follow-up.

Clinical and hemodynamic outcomes up to 7 years after transcatheter pulmonary valve replacement in the US melody valve investigational device exemption trial

Background— Studies of transcatheter pulmonary valve (TPV) replacement with the Melody valve have demonstrated good short-term outcomes, but there are no published long-term follow-up data. Methods and Results— The US Investigational Device Exemption trial prospectively enrolled 171 pediatric and adult patients (median age, 19 years) with right ventricular outflow tract conduit obstruction or regurgitation. The 148 patients who received and were discharged with a TPV were followed up annually according to a standardized protocol. During a median follow-up of 4.5 years (range, 0.4–7 years), 32 patients underwent right ventricular outflow tract reintervention for obstruction (n=27, with stent fracture in 22), endocarditis (n=3, 2 with stenosis and 1 with pulmonary regurgitation), or right ventricular dysfunction (n=2). Eleven patients had the TPV explanted as an initial or second reintervention. Five-year freedom from reintervention and explantation was 76±4% and 92±3%, respectively. A conduit prestent and lower discharge right ventricular outflow tract gradient were associated with longer freedom from reintervention. In the 113 patients who were alive and reintervention free, the follow-up gradient (median, 4.5 years after implantation) was unchanged from early post-TPV replacement, and all but 1 patient had mild or less pulmonary regurgitation. Almost all patients were in New York Heart Association class I or II. More severely impaired baseline spirometry was associated with a lower likelihood of improvement in exercise function after TPV replacement. Conclusions— TPV replacement with the Melody valve provided good hemodynamic and clinical outcomes up to 7 years after implantation. Primary valve failure was rare. The main cause of TPV dysfunction was stenosis related to stent fracture, which was uncommon once prestenting became more widely adopted. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT00740870.

Balloon angioplasty for recurrent coarctation of aorta. Immediate and long-term results.

BACKGROUNDnAs angioplasty techniques have been refined and larger low-profile balloons developed, a nonsurgical approach to recoarctation has become available. Several reports have documented both the efficacy and safety of this procedure. However, there are little data available on the long-term follow-up of these patients. This report details the initial results and long-term evaluation of both the relief of obstruction and the presence of hypertension after balloon angioplasty for recurrent coarctation.nnnMETHODS AND RESULTSnBalloon angioplasty for recurrent coarctation of the aorta was performed 29 times in 26 patients at a median age of 4 years and 9 months (range, 4 months to 29 years), with eight patients less than 1 year old. Initial surgical techniques were end-to-end anastomosis in 11 patients, subclavian flap aortoplasty in 11 patients, and patch aortoplasty in four patients. Angioplasty was performed at a median interval of 2 years and 7 months (range, 4 months to 23 years) after surgery. Mean peak systolic pressure difference across the coarctation decreased from 40.0 +/- 16.8 to 10.3 +/- 9.5 mm Hg (p less than 0.05) after the initial angioplasty, and mean diameter of the aortic lumen at the coarctation site increased from 5.8 +/- 3.5 to 9.0 +/- 4.3 mm (p less than 0.05). There was no mortality, and only one patient developed an aneurysm (4%). Three patients underwent repeat angioplasty for a pressure difference of more than 20 mm Hg. Long-term follow-up is available on 24 of 26 patients with a mean follow-up of 42 +/- 24 months (range, 12-88 months). Mean peak systolic pressure difference across the area of coarctation decreased from 40.3 +/- 17.4 before angioplasty to 8.5 +/- 8.3 mm Hg after final angioplasty (p less than 0.05) and 7.5 +/- 7.5 mm Hg at follow-up. Mean peak systolic blood pressure in the upper extremities decreased from 133.1 +/- 14.9 before angioplasty to 111.1 +/- 14.1 mm Hg at long-term follow-up (p less than 0.05).nnnCONCLUSIONSnBalloon angioplasty should be considered the treatment of choice for relief of recurrent aortic coarctation.

Hemodynamic evaluation before and after closure of fenestrated Fontan. An acute study of changes in oxygen delivery.

BackgroundAcute changes in hemodynamics and oxygen delivery accompanying temporary occlusion of atrial defects in 14 patients after a fenestrated Fontan procedure were evaluated at a median interval of 32 days after surgery to identify candidates for permanent transcatheter closure of their defects. Methods and ResultsPatients ranged in age from 9 months to 33 years and in weight from 7.9 to 69 kg. Right atrial (RA), left atrial (IA), and aortic pressures, mixed venous (Smvo2) and aortic (Sao2) oxygen saturation, and whole-body oxygen consumption (Vo2) were measured, and systemic blood flow (Qs), systemic oxygen transport (SOT), and oxygen extraction were calculated before and after occlusion. Smvo2, Vo2, and RA pressures did not change, but Sao2 increased from 84±6% to 95±3% (p<0.05), and IA pressures fell from 5.1±3.6 to 3.7±2.2 mm Hg (p<0.05). Qs fell from 2.4±0.7 to 1.8±0.411 · min−1 · m−2 (p<0.05), SOT fell from 425±154 to 366±112 ml · O2 · min−1 · m−2 (p<0.05), and oxygen extraction increased from 0.40±0.12 to 0.46±0.13 (p<0.05). Only one patient did not undergo definitive closure of his defect because of a marked decrease in Qs and SOT with a significant rise in RA pressure. ConclusionsAlthough delayed closure of an atrial defect in these patients improved morbidity and mortality, the complete separation of the venous and systemic circulations was accomplished at the expense of decreased Qs and oxygen delivery despite the improved level of arterial oxygenation. The resting levels of oxygen extraction are elevated and will be associated with decreased exercise capability. The long-term benefits of closure of these fenestrations are yet to be shown.

Radionuclide assessment of right and left ventricular exercise reserve after total correction of tetralogy of Fallot

First pass radionuclide angiocardiography under conditions of rest and exercise was utilized to evaluate a group of 16 postoperative patients who had undergone total surgical correction of tetralogy of Fallot. Functional data were related to thallium-201 myocardial imaging at rest, a noninvasive means of detecting right ventricular hypertrophy. All 16 patients were asymptomatic and 15 demonstrated normal right ventricular ejection fraction (equal to or greater than 45 percent) at rest. However, 13 patients manifested abnormal right ventricular ejection fraction responses to exercise (normal response is an absolute increment in an ejection fraction of 5 or greater percent). For the entire group, right ventricular ejection fraction at rest was 55 +/- 2 percent, whereas at exercise it was 52 +/- 2 percent (p = not significant). In contrast, left ventricular ejection fraction responses were normal in all patients. Thallium-201 imaging revealed substantial right ventricular uptake consistent with residual right ventricular hypertrophy, which was quantifiable in all patients. Thus, abnormalities in right ventricular performance during exercise may be detected readily by this radionuclide approach in these postoperative patients despite their asymptomatic clinical status and generally normal right ventricular performance at rest.

Predictors of rhythm disturbances and subsequent morbidity after the Fontan operation

The electrocardiographic, hemodynamic and surgical data of 30 patients who underwent a Fontan operation between 1977 and 1986 were retrospectively reviewed to identify the incidence and predictors of immediate and late postoperative arrhythmias and associated morbidity in long-term survivors. Of 4 patients who died less than 1 year after operation (mortality 13%), 1 death was related to an arrhythmia. Three patients were not in sinus rhythm before operation and were excluded from the statistical analysis that examined predictors of arrhythmias. The remaining 23 long-term survivors have been followed 6.3 +/- 2.6 years (mean +/- standard deviation) since surgery and all remain in New York Heart Association functional class I or II. Ten patients (43%) developed immediate postoperative arrhythmias (less than or equal to 30 days) whereas 11 (48%) had late arrhythmias. With up to 10.7 years of follow-up, the proportion of patients free from late arrhythmias continues to decline. Arrhythmias included bradyarrhythmias, atrial tachyarrhythmias, the tachy-brady syndrome and supraventricular ectopic activity. Immediate postoperative arrhythmias predicted late arrhythmias (p = 0.022). The preoperative electrocardiogram was the only variable useful in predicting both immediate and late postoperative arrhythmias. A more negative P-wave deflection in lead V1 (-2.4 +/- 0.7 vs -1.4 +/- 1.2 mV, p = 0.02) predicted patients with immediate postoperative arrhythmias, whereas both greater P-wave duration and a more negative deflection in this lead predicted late arrhythmias (103 +/- 14 vs 83 +/- 20 ms, p = 0.01, and -2.5 +/- 0.8 vs -1.3 +/- 1.0 mV, p = 0.005, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Repair of Aortic Coarctation in the First Three Months of Life: Immediate and Long-Term Results

The optimum surgical procedure for treatment of coarctation of the aorta in the neonatal period remains controversial. To assess immediate and long-term results of using primarily the subclavian flap angioplasty procedure (SFA), we reviewed our initial 5-year experience. The average follow-up was 6 years. From 1977 to 1981, 25 infants under 3 months of age (1 to 86 days, mean 21) required emergency surgery for repair of coarctation of the aorta. Three groups of patients were identified. Group I consisted of 10 patients with or without patent ductus arteriosus. In group II, 10 patients had coarctation association with one or multiple ventricular septal defects (VSDs) without other congenital defects. In group III, 5 patients had coarctation associated with more complex congenital heart lesions. Twenty-three SFAs and two patch aortoplasties were performed. No patient with isolated VSD was banded. All patients except one in group III with an associated atrioventricular canal survived initial hospitalizations. Four late deaths occurred, all in patients with associated complex heart defects. There were three recurrent coarctations requiring surgery or balloon angioplasty (12%)--one in each group, with a total rate of 0.77 recurrences per 100 patient-months. SFA for coarctation in the neonatal period is a safe and effective operation with a low initial mortality (4%, 0-19%, 70% confidence limits) well tolerated in this group of ill patients. Long-term outcome is primarily related to the presence of associated complex congenital defects. Infants with VSD associated with coarctation did not require pulmonary artery banding unless primary intracardiac repair was not feasible.(ABSTRACT TRUNCATED AT 250 WORDS)

Echocardiographic assessment of the severity of aortic stenosis in children and adolescents.

The magnitude of ventricular hypertrophy in response to afterloading is determined by wall stress, with wall thickness increasing in proportion to ventricular load until systolic wall stress is normalized. With use of echocardiographic measurements of left ventricular end-systolic wall thickness (Ws) and cavity transverse dimension (Ds), the pressure constant k was calculated in 16 patients without left heart obstruction according to the formula k = P-Ds/Ws. The mean value for k was 225 +/- 6.7 (standard deviation) mm Hg. From this value, left ventricular pressure was estimated in 13 patients with aortic stenosis aged 4 to 17 years using the formula P = k-Ws/Ds. No subject had evidence of cardiac failure. Peak systolic aortic pressure difference (delta P) was calculated by subtracting cuff-measured brachial arterial peak systolic pressure from the estimated left ventricular pressure. Excellent correlation was obtained between the estimated delta P and that found at cardiac catheterization (r = 0.89). In two patients, echocardiographic data predicted significant obstruction in the presence of normal electrocardiographic, vectorcardiographic and vector lead tracings. Echocardiography offers a noninvasive method for estimating the severity of aortic stenosis, in the absence of myocardial failure; it appears to be more sensitive than other currently employed techniques.