Characterization of reentrant circuit in macroreentrant right atrial tachycardia after surgical repair of congenital heart disease: isolated channels between scars allow "focal" ablation.

BACKGROUND: The purpose of this study was to characterize the circuit of macroreentrant right atrial tachycardia (MacroAT) in patients after surgical repair of congenital heart disease (SR-CHD). METHODS AND RESULTS: Sixteen patients with atrial tachycardia (AT) after SR-CHD were studied (atrial septal defect in 6, tetralogy of Fallot in 4, and Fontan procedure in 6). Electroanatomic right atrial maps were obtained during 15 MacroATs in 13 patients, focal AT in 1 patient, and atrial pacing in 2 patients without stable AT. A large area of low bipolar voltage (/=2 scars forming narrow channels. Ablation within the channels eliminates MacroAT.

Diagnostic studies for systemic necrotizing vasculitis. Sensitivity, specificity, and predictive value in patients with multisystem disease.

Forty patients with multisystem disease and suspected systemic necrotizing vasculitis were evaluated with a protocol designed to confirm the diagnosis with sequential testing. All patients underwent initial laboratory testing. Subsequent studies were individualized to the patient starting with "safe" tests (skin, muscle, rectal biopsies) and progressing to "invasive" tests (arteriography, kidney and lung biopsies). No single laboratory study was found to have adequate predictive value. Skin biopsy, rectal biopsy, and arteriography were insensitive, nonspecific, or had poor predictive values. Muscle biopsy was the most valuable safe procedure (sensitivity, 50%; specificity, 100%; predictive value, 100%; predictive value of negative biopsy, 76%; efficiency, 64%). A diagnostic approach to the patient with possible systemic necrotizing vasculitis is described.

Usefulness of adenosine for arrhythmias in infants and children.

Adenosine was administered to 25 infants and children (11 patients after presenting with a sustained arrhythmia, and 14 during a diagnostic electrophysiologic study) to determine its electrophysiologic effects. Adenosine was given as an intravenous bolus (starting dose 37.5 micrograms/kg, and increased by 37.5 micrograms/kg increments until an effect was seen). Adenosine caused tachycardia termination or transient increased atrioventricular (AV) block in all 25 patients. Seven patients had tachycardia requiring only the atria for perpetuation and developed increased AV nodal block (minimum effective adenosine dose range 37.5 to 350 micrograms/kg, mean 131). Thirteen had AV reciprocating tachycardia or AV node reentry tachycardia (minimum effective adenosine dose range 37.5 to 225 micrograms/kg, mean 114). Four other patients received adenosine to rule out preexcitation (minimum effective adenosine dose range 37.5 to 375 micrograms/kg, mean 165). One of the 25 patients had junctional ectopic tachycardia and adenosine administration caused retrograde AV block. Six of the 25 (24%) had noticeable but minor side effects. One patient had sustained bradycardia (2 to 3 minutes requiring temporary pacing). Adenosine is a safe and effective agent in the evaluation and treatment of infants and children with arrhythmias.

Transesophageal study of recurrent atrial tachycardia after atrial baffle procedures for complete transposition of the great arteries.

Transesophageal study was used for diagnosis and treatment of 51 episodes of tachycardia in 13 patients with complete transposition of the great arteries who had undergone atrial baffle procedure. At the time of atrial baffle procedure, patients were 6 to 36 months old (mean 23). Tachycardia (1 to 17 episodes per patient) first occurred 1 to 23 days (4 patients) or 1.8 to 12 years (9 patients) after atrial baffle. Transesophageal study was performed using a bipolar silicone rubber-coated catheter. Tachycardia conversion was accomplished with stimulation bursts using 4 to 10 stimuli 9.9 ms in duration at 20 to 28 mA and an interstimulus interval of 50 to 100 ms less than the atrial cycle length. All tachycardia episodes had regular atrial cycle lengths ranging from 200 to 350 ms. In 12 patients, second-degree atrioventricular (AV) block was observed during tachycardia, suggesting primary atrial tachycardia. However, in 1 patient, occurrence of AV block always resulted in tachycardia termination, suggesting the presence of AV reentrant tachycardia. Transesophageal stimulation converted 48 of 51 tachycardia episodes to sinus/junctional rhythm. Ten tachycardia episodes in 6 patients were transiently converted to atrial fibrillation lasting 3 seconds to 28 minutes before spontaneous conversion to sinus junctional rhythm. Conversion attempts were unsuccessful on 3 occasions. Acceleration of ventricular rate after stimulation necessitated DC cardioversion on 1 occasion. Conversion was not achieved in 2 tachycardia episodes using stimuli less than 10 mA. Transesophageal study is a safe and effective minimally invasive technique for diagnosis and treatment of tachycardia in infants and children who have had atrial baffle for transposition of the great arteries.

Cryopreserved homograft valves in the pulmonary position: risk analysis for intermediate-term failure.

OBJECTIVE: The purpose of this study was to examine the durability of cryopreserved homografts used to replace the "pulmonary" valve and to identify factors associated with their late deterioration. METHODS: We reviewed our entire experience (1985-1997) with 331 survivors in whom cryopreserved homograft valves (pulmonary, n = 304; aortic, n = 27) were used to reconstruct the pulmonary outflow tract. Median age was 14 years (range, 2 days-62 years). Operations included Ross operation (n = 259), tetralogy of Fallot (n = 41), truncus arteriosus (n = 14), Rastelli operation (n = 11), and others (n = 6). Median follow-up was 3.8 years (range, 0.2-11.2 years); late echographic follow-up was complete for 97% of patients. Homograft failure was defined as the need for explantation and valve-related death; homograft dysfunction was defined as a pulmonary insufficiency grade 3/4 or greater and a transvalvular gradient of 40 mm Hg or greater. RESULTS: Homograft failure occurred in 9% (30 of 331 patients; Kaplan-Meier); freedom from failure was 82% +/- 4% at 8 years. Homograft dysfunction occurred in 12% (39 of 331 patients), although freedom from dysfunction was 76% +/- 4% at 8 years. For aortic homografts, this was 56% +/- 11%, compared to 80% +/- 4% for pulmonary homografts (P =.003). For patients aged less than 3 years (n = 38), this was 51% +/- 12%, compared with 87% +/- 4% for older patients (P =.0001). By multivariable analysis, younger age of homograft donors, non-Ross operation, and later year of operation were associated with homograft failure; younger age of homograft donors, later year of operation, and use of an aortic homograft were associated with homograft dysfunction. CONCLUSIONS: Homograft valves function satisfactorily in the pulmonary position at mid-term follow-up. The pulmonary homograft valve appears to be more durable than the aortic homograft valve in the pulmonary position.

Neonatal repair of Ebstein's anomaly: indications, surgical technique, and medium-term follow-up.

BACKGROUND: Ebstein's anomaly in the severely symptomatic neonate is usually fatal. Because the mortality for various surgical interventions has been prohibitively high, the indications for operation in these critically ill neonates are unclear. METHODS: We reviewed our results with biventricular repair of three consecutive severely symptomatic neonates (2.8 to 3.2 kg) at our institution since 1994. Each had associated complex cardiac pathology, including multiple muscular ventricular septal defects (n = 1), pulmonary stenosis with functional pulmonary atresia (n = 1), and anatomic pulmonary atresia (n = 1). Preoperatively, all infants had severe tricuspid regurgitation, Great Ormond Street Ebstein echocardiogram scores greater than 1.3:1 (grade 3 or 4) and cardiothoracic ratio greater than 0.85. Two patients were severely cyanotic. Hepatic and renal insufficiency with diffuse coagulopathy was present preoperatively in two patients. Surgical repair consisted of (1) reconstruction of a competent monocuspid tricuspid valve, (2) right ventriculorrhaphy, (3) subtotal closure of atrial septal defect (ASD), (4) aggressive reduction atrioplasty, and (5) repair of all associated cardiac defects. RESULTS: There were no early or late deaths. All patients are currently asymptomatic, without medications, and in sinus rhythm. At 5-year follow-up, trivial tricuspid regurgitation is present in 1 and mild regurgitation in 2 patients. On the basis of these results and review of the current literature, we propose new indications for surgical repair in the neonate with Ebstein's anomaly. CONCLUSIONS: Biventricular repair of Ebstein's anomaly in the critically ill neonate is feasible and medium-term durability of the repair is excellent. Therefore, conventional management of these patients should be revised and early surgical repair encouraged.

Transseptal decompression of the left heart during ECMO for severe myocarditis.

A 16-month-old boy suffered a cardiac arrest as a result of acute myocarditis, and venoarterial extracorporeal membrane oxygenation was instituted. Twelve hours later, acute left heart distention developed with cessation of left ventricular ejection. Under transesophageal echocardiographic guidance, a long introducer was placed into the left atrium through a transseptal puncture and connected in-line to the venous circuit. Within hours, left ventricular function improved and ejection returned. Left heart decompression was continued for 5 days, and the patient was weaned from extracorporeal membrane oxygenation after 6 days with normal cardiac and neurologic function.

Treatment of absent pulmonary valve syndrome with homograft.

We report the successful treatment of absent pulmonary valve syndrome in an infant. The treatment consisted of intracardiac repair of pulmonary regurgitation with a homograft valve, which allowed for early extubation and survival.

Correction of truncus arteriosus with truncal valvar stenosis or insufficiency using two homografts.

Surgical correction of truncus arteriosus requires the creation of right ventricular to pulmonary artery continuity and closure of the ventricular septal defect. A variety of conduits have been used including valved and nonvalved. Despite a significant incidence of truncal valvar stenosis and insufficiency, this valve has seldom been replaced. We present 4 cases of truncus arteriosus with truncal valvar stenosis or insufficiency that were repaired using two valved homografts: one to create the pulmonary outflow tract and the other to replace the abnormal truncal valve. Two of these patients are doing well after 4 months. Another child survived the operation and did well for 2 months when she died suddenly. The last child died 14 hours postoperatively from low cardiac output syndrome secondary to diabetic hypertrophic cardiomyopathy. When truncal valvar abnormalities are present, the primary repair of truncus arteriosus in an infant should include replacement of the truncal valve. Total correction can be successfully achieved using two valved homografts, resulting in long-term palliation and freedom from thromboembolic events and the use of anticoagulants.

Ventricular function after the arterial switch operation for transposition of the great arteries.

The theoretical advantages of anatomical repair have resulted in the widespread use of the arterial switch operation for transposition of the great arteries. However, preservation of systemic ventricular performance and late functional results have not been well documented. To evaluate late postoperative ventricular function, we reviewed 53 consecutive patients undergoing arterial switch operation for transposition of the great arteries with or without a ventricular septal defect over the 8-year period from March 1985 to 1993. Forty-two patients had simple transposition of the great arteries and 11 patients had associated ventricular septal defects that were closed at operation. Mean age at operation was 1.8 months (range, 1 day to 36 months), and mean patient weight was 3.8 kg (range, 1.8 to 15.6 kg). All but 8 patients were neonates. There were six operative deaths (11.3%, 6/53) and two late deaths during a median follow-up of 23 months (range, 0.1 to 99.5 months). Actuarial survival at 8 years was 83% +/- 6%. Left ventricular outflow tract obstruction has not been identified, and 9 patients (20%, 9/45) have right ventricular outflow tract gradients exceeding 20 mm Hg, 3 of whom have required reoperation. Eighteen patients have mild neo-aortic valve regurgitation. All survivors are currently in New York Heart Association class I, and are in sinus rhythm. Systolic left ventricular function is well preserved with ejection fractions greater than 0.60 in all survivors followed up for more than 4 months (41 patients). Left ventricular end-diastolic volume index is elevated in only 1 patient, a patient who had pulmonary artery banding as a neonate.(ABSTRACT TRUNCATED AT 250 WORDS)

Associated atrial septal defects increase perioperative morbidity after ventricular septal defect repair in infancy.

Although closure of ventricular septal defects (VSDs) is currently associated with a relatively low risk, infants with associated atrial septal defects (ASDs) seem to have a higher perioperative morbidity. To clarify this impression, we reviewed our entire experience (since 1977) with closure of simple VSDs in 163 infants (age, < or = 12 months). Of these, 57 had significant ASDs (ASD-VSD subgroup). Hospital mortality was 3.7% (6/163) overall and 1.4% (2/145) since 1980. Actuarial survival at 10 years was 92% +/- 5%. Significant morbidity occurred in 15.5% (16/103) of the VSD subgroup versus 48.1% (26/54) of the ASD-VSD subgroup (p < or = 0.001). Multivariate analysis identified the presence of multiple VSDs and early date of operation as risk factors for hospital death, and younger age, an associated ASD, the size of the VSD, and use of hypothermic circulatory arrest as risk factors for significant perioperative morbidity. Compared with the VSD subgroup, the ASD-VSD subgroup had a higher hospital mortality (5.3% [3/57] versus 2.8% [3/106]), were younger (5.1 +/- 2.9 versus 7.2 +/- 2.9 months; p = 0.001), had a higher preoperative pulmonary artery pressure (70.2 +/- 19.0 versus 62.7 +/- 21.8 mm Hg; p = 0.08), needed more inotropic support (12.3% versus 3.7%; p = 0.07), needed more prolonged ventilation (3.3 versus 1.8 days; p = 0.02), and had longer postoperative hospital stays (11 versus 8 days; p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Modified hemi-Fontan operation: an alternative definitive palliation for high-risk patients.

BACKGROUND: We conceptualized that by adding small amounts of prograde pulmonary blood flow to the hemi-Fontan operation, or bidirectional Glenn procedure, this modified hemi-Fontan operation could be safely done at an early age, with better oxygenation, and with less potential for pulmonary arteriovenous fistulae. METHODS: Since April 1992 the hemi-Fontan operation was modified by adding some prograde flow through the native pulmonary artery in 10 high-risk infants, either by leaving the critical subpulmonary stenosis untreated (n = 6) or by tightening a previously placed pulmonary artery band (n = 4). All other sources of pulmonary blood flow were interrupted. Patients were 4 to 23 months old (3.8 to 10.3 kg). Diagnoses included isolated dextrocardia with single ventricle (3) and polysplenia syndrome (2). Cardiopulmonary bypass was needed in 5 patients. RESULTS: There were no hospital deaths. Mean postoperative intensive care unit stay was 2 days, and 9 of 10 patients were discharged within 7 days of operation. One 4-month-old infant with Down's syndrome survived postoperative takedown of the hemi-Fontan repair after pneumonia and caval thrombosis developed. Eight patients are currently asymptomatic receiving minimal modification, and oxygen saturations range from 84% to 93%. CONCLUSIONS: Adding small volumes of prograde pulmonary blood flow to the hemi-Fontan operation is safe, provides improved oxygenation, may encourage growth of central pulmonary arteries, and represent an alternative definitive palliation for high-risk Fontan candidates.

Cochlear microphonic measurements of interaural time differences in the chick.

The major cues for the sound localization are the interaural differences in the timing and intensity of acoustic information. This poses a difficult coding problem for animals with relatively small heads, such as birds, because interaural time differences (ITDs) would have a small range and magnitude and interaural intensity differences (IIDs) would be significant for only high frequency sounds. It has been suggested that this coding problem is mitigated in birds by an enhancement of ITDs and IIDs resulting from the acoustic coupling of the two middle ear cavities through an interaural canal. In this report, the functional ITDs for sounds at different azimuthal locations were recorded in young chicks, and the contribution of middle ear acoustic coupling was evaluated. ITDs were calculated from simultaneous cochlear microphonic (CM) recordings evoked by pure tone stimuli. These effective ITDs were larger than predicted by the physical separation of the two ears, and this enhancement was more pronounced at low (0.8 and 1 kHz) than at high (2 and 4 kHz) frequencies, reaching maximum values of approximately 180 and 100 microseconds, respectively. The amplitude of the CM also varied as a function of sound source location. This variation was as much as +/- 30%, even for the low frequency tones. This suggests that IID cues are also available to the chick. To determine the contribution of middle ear acoustic coupling to the timing and amplitude of the CM response, the CM in one ear was measured prior to, and following occlusion of the contralateral external auditory canal. The cochlear microphonic from the ear distal to the sound source advanced in time and increased in amplitude when the ear proximal to the sound source was sealed. These effects were more pronounced for low frequency sounds. These findings confirm that acoustic coupling of the middle ear cavities plays a role in enhancing sound localization cues in the chick.

Evaluation of cryopreserved homografts in the right ventricular outflow tract after the Ross procedure: intermediate-term follow up.

BACKGROUND AND AIMS OF THE STUDY: The Ross procedure involves replacing a transplanted pulmonary valve with a cryopreserved homograft in order to re-establish right ventricle-pulmonary artery continuity. This study reviews mid-term results of such surgery in children and young adults. METHODS: Since November 1986, 114 patients have undergone the Ross procedure at the Children's Hospital of Oklahoma using cryopreserved pulmonary homografts (n = 113) and aortic homograft (n = 1) to reconstruct the right ventricular outflow tract. Graft size ranged from 16 to 32 mm. Ninety-three patients (mean age at implant 10.4 years (range: 0.8-22 years) have had complete mean follow up of 3.2 years (range: 5 months to 8.4 years) after surgery. Homograft evaluation included clinical reports and comparison of early post-implant and latest echocardiography. Measurements of homograft valve annulus and peak instantaneous Doppler gradient were compared; quality of valve leaflets, location of obstruction, and the degree of pulmonary regurgitation were assessed. RESULTS: Compared with early postoperative data, mean homograft annulus size decreased by 15% (p < 0.0001); in 88% of patients, the decrease ranged from one to nine millimeter. Peak Doppler gradient increased significantly (from 10 to 17 mmHg, p < 0.0001); 25% of patients developed gradients > 25 mmHg, and four had gradients > 50 mmHg. Significant obstruction developed most often at the supravalvular level or in the homograft conduit itself. This usually occurred within one year of implant, and was associated with calcification and contracture of the homograft wall. Significant pulmonary regurgitation developed in 19 cases (20%), but was more than mild in only three. Leaflet integrity was maintained except in those who developed severe stenosis or regurgitation. Two patients have undergone re-operation for homograft stenosis 2.8 and 5.4 years respectively after the Ross procedure; one has developed recurrent severe stenosis in the homograft four months later. CONCLUSIONS: After the Ross procedure: (i) Pulmonary homografts undergo significant annular reduction in most patients, though this is usually not associated with the development of significant obstruction. (ii) Peak Doppler gradients across the homograft increase in most patients, though only 4% develop more than mild obstruction. (iii) Mild pulmonary regurgitation is common (20%); moderate or severe regurgitation is rare and usually develops in concert with severe stenosis. (iv) Severe homograft valve degeneration usually occurs within one year of implant, and may reflect an immune-mediated response.

Medium-term follow-up of pulmonary autograft replacement of aortic valves in children.

Pulmonary autograft replacement (PAG) of the aortic valve in children has been shown to be safe and effective with a low incidence of late valve dysfunction. Relief of all types of left ventricular outflow tract obstruction using the pulmonary root has been possible. Concern about the durability of the pulmonary root in the aortic position, and the potential for growth of the pulmonary autograft used either as a root replacement or intraaortic implant, has been questioned. Sixty-five consecutive patients, aged 1.8 to 21 years (mean 12 years) operated on between September 1986 and January 1993, 35 with an intra-aortic implant (IA) and 30 with root replacement (RR), were evaluated by clinical and serial echocardiographic studies (ECHO) up to 6.5 years post-operatively. The hospital mortality rate was 3.0% (70% CL 2.1-5.1%). Two patients required reoperation for PAG insufficiency (AI), one for technical malalignment necessitating replacement at 6 months, and one with progressive leaflet prolapse due to adherence of the valve leaflet to a ventricular septal defect (VSD) patch. Freedom from significant aortic regurgitation at 6-year follow-up was 100% for RR and 91 +/- 6% for IA, and freedom from all valve-related complications including reoperation was 92 +/- 5% at 6 years. Significant enlargement of the aortic annulus which parallels somatic growth has been measured by ECHO in 17 IA implants (P < 0.001) and 17 RR patients (P < 0.01) by 1 year, and in 10 IA (P = 0.007) and 6 RR (P < 0.05) by 2 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Necrotizing fasciitis of the eyelids.

Necrotizing fasciitis is a destructive soft tissue infection that rarely involves the eyelids. Three cases of necrotizing fasciitis of the eyelids are described. Necrotizing fasciitis was preceded by minor forehead soft tissue trauma in two cases and occurred spontaneously in one. In two patients necrotizing fasciitis was bilateral and involved both the upper and lower eyelids. Review of these cases, in addition to 18 cases previously reported in the English literature, reveals a predominance in females, preceding minor local soft tissue trauma, frequent bilateral involvement, and an association with alcohol abuse and diabetes. In all of the patients, group A beta-hemolytic streptococci were cultured from the wound. Early recognition of the disease process, prompt surgical debridement of the necrotic tissue, aggressive antimicrobial therapy, and delayed skin grafting combine to minimize morbidity.

Severe reversible dilated cardiomyopathy associated with a large left ventricular thrombus in a young child with middle aortic syndrome.

We report a case of a seven-year girl who presented with severe dilated cardiomyopathy (DCM) associated with a large thrombus in the left ventricle (LV). She had a long segment stenosis of the lower thoracic descending aorta, possibly due to non-specific aortitis and underwent successful stent angioplasty. The LV thrombus resolved after heparin without sequelae.