Home use of a compact, 12­lead ECG recording system for newborns.

BACKGROUND: An easy-to-operate ECG recorder should be useful for newborn screening for heart conditions, by health care workers - or parents. We developed a one-piece electrode strip and a compact, 12­lead ECG recorder for newborns. METHOD: We enrolled 2582 newborns in a trial to assess abilities of parents to record a 12­lead ECG on their infants (2-4 weeks-old). Newborns were randomized to recordings by parents (1290) or our staff (1292 controls). Educational backgrounds of parents varied, including 64% with no more than a high school diploma. RESULTS: For newborns randomized to parent recorded ECGs, 94% of parents completed a 10-minute recording. However, 42.6% asked for verbal help, and 12.7% needed physical help. ECG quality was the same for recordings by parents versus staff. CONCLUSIONS: By use of a one-piece electrode strip and a compact recorder, 87% of parents recorded diagnostic quality ECGs on their newborn infants, with minimal assistance.

Comparison of formulas for calculation of the corrected QT interval in infants and young children.

OBJECTIVE: To compare 4 heart rate correction formulas for calculation of the rate corrected QT (QTc) interval among infants and young children. STUDY DESIGN: R-R and QT intervals were measured from digital electrocardiograms. QTc were calculated with the Bazett, Fridericia, Hodges, and Framingham formulas. QTc vs R-R graphs were plotted, and slopes of the regression lines compared. Slopes of QTc-R-R regression lines close to zero indicate consistent QT corrections over the range of heart rates. RESULTS: We reviewed electrocardiograms from 702 children, with 233 (33%) <1 year of age and 567 (81%) <2 years. The average heart rate was 122 ± 20 bpm (median 121 bpm). The slopes of the QTc-R-R regression lines for the 4 correction formulas were -0.019 (Bazett); 0.1028 (Fridericia); -0.1241 (Hodges); and 0.2748 (Framingham). With the Bazett formula, a QTc >460 ms was 2 SDs above the mean, compared with "prolonged" QTc values of 414, 443, and 353 ms for the Fridericia, Hodges, and Framingham formulas, respectively. CONCLUSIONS: The Bazett formula calculated the most consistent QTc; 460 ms is the best threshold for prolonged QTc. The study supports continued use of the Bazett formula for infants and children and differs from the use of the Fridericia correction during clinical trials of new medications.

Genetic variants for long QT syndrome among infants and children from a statewide newborn hearing screening program cohort.

OBJECTIVES: Autosomal recessive long QT syndrome (LQTS), or Jervell and Lange-Nielsen syndrome (JLNS), can be associated with sensorineural hearing loss. We aimed to explore newborn hearing screening combined with electrocardiograms (ECGs) for early JLNS detection. STUDY DESIGN: In California, we conducted statewide, prospective ECG screening of children ≤ 6 years of age with unilateral or bilateral, severe or profound, sensorineural or mixed hearing loss. Families were identified through newborn hearing screening and interviewed about medical and family histories. Twelve-lead ECGs were obtained. Those with positive histories or heart rate corrected QT (QTc) intervals ≥ 450 ms had repeat ECGs. DNA sequencing of 12 LQTS genes was performed for repeat QTc intervals ≥ 450 ms. RESULTS: We screened 707 subjects by ECGs (number screened/number of responses = 91%; number of responses/number of families who were mailed invitations = 54%). Of these, 73 had repeat ECGs, and 19 underwent gene testing. No subject had homozygous or compound heterozygous LQTS mutations, as in JLNS. However, 3 individuals (with QTc intervals of 472, 457, and 456 ms, respectively) were heterozygous for variants that cause truncation or missplicing: 2 in KCNQ1 (c.1343dupC or p.Glu449Argfs*14; c.1590+1G>A or p.Glu530sp) and 1 in SCN5A (c.5872C>T or p.Arg1958*). CONCLUSIONS: In contrast to reports of JLNS in up to 4% of children with sensorineural hearing loss, we found no examples of JLNS. Because the 3 variants identified were unrelated to hearing, they likely represent the prevalence of potential LQTS mutations in the general population. Further studies are needed to define consequences of such mutations and assess the overall prevalence.

Outcome of patients with double-inlet left ventricle or tricuspid atresia with transposed great arteries.

OBJECTIVES: We sought to determine the long-term outcomes and risk factors for mortality in patients with double-inlet left ventricle (DILV) or tricuspid atresia with transposed great arteries (TA-TGA). BACKGROUND: Patients with DILV or TA-TGA are at risk of systemic outflow obstruction and a poor outcome. The impact of various management strategies on the long-term outcomes of these patients remains unknown. METHODS: We reviewed the outcomes of 164 consecutive pediatric patients with DILV or TA-TGA who underwent surgical palliation between 1983 and 2002. Patients with a Holmes heart or heterotaxy syndrome or who were lost to follow-up (n = 24) were excluded. Risk factors for mortality or the need for orthotopic heart transplantation (OHT) were assessed by multivariate analysis. RESULTS: There were 105 patients with DILV and 35 patients with TA-TGA. The overall mortality rate, including OHT, was 29%. Patients with DILV had a lower mortality rate than patients with TA-TGA (23% vs. 49%, p = 0.007). Multivariate analysis showed the presence of arrhythmia and pacemaker requirement as independent risk factors for mortality, whereas pulmonary atresia or stenosis and pulmonary artery banding were associated with decreased mortality. Gender, era of birth, aortic arch anomaly, and systemic outflow obstruction were not risk factors. The perioperative and overall mortality were similar between patients who underwent the Damus-Kaye-Stansel procedure beyond the neonatal period and those had subaortic resection. CONCLUSIONS: The mortality of patients with DILV or TA-TGA remains high. The outcomes of these patients are influenced by restriction of pulmonary blood flow, arrhythmia, and pacemaker requirement. Surgical palliation to relieve systemic outflow obstruction is not associated with a poor outcome.

Usefulness of B-type natriuretic peptide as a noninvasive screening tool for cardiac allograft pathology in pediatric heart transplant recipients.

We examined the utility of B-type natriuretic peptide (BNP) in the evaluation of pediatric orthotopic heart transplant recipients for allograft pathology by measuring the serum BNP levels at the time of either screening echocardiography and biopsy, or at the time of clinical rejection. There was a significant difference (p <0.0001) in the BNP levels in 37 patients in the group with evidence of pathology compared with those without evidence. There was also 100% sensitivity and 100% negative predictive value of BNP levels >100 pg/ml for identifying graft pathology.

Outcome of staged surgical approach to neonates with single left ventricle and moderate size bulboventricular foramen.

Neonates with double-inlet left ventricle or tricuspid atresia with transposed great arteries and a bulboventricular foramen (BVF) area <2 cm(2)/m(2) develop BVF obstruction. This study examined the outcome of neonates with BVF area between 1 and 2 cm(2)/m(2) whose BVF was bypassed after the neonatal period. We reviewed 29 neonates with double-inlet left ventricles (n = 18) or tricuspid atresia (n = 11) and transposed great arteries. The study group consisted of 9 patients with neonatal BVF areas of 1 to 2 cm(2)/m(2) who did not undergo repair of the BVF obstruction as a neonate. The comparison group consisted of 8 "ideal" patients without BVF obstruction. Precavopulmonary shunt data from cardiac catheterization and echocardiogram and outcomes of the cavopulmonary shunt were compared. Study group patients developed a mild BVF gradient (18 +/- 10 mm Hg by cardiac catheterization) by a mean of 7 months. Left ventricular wall thickness, however, remained in the normal range (4.2 +/- 0.3 mm) and was not statistically different from the comparison group (4.1 +/- 0.4 mm). No difference was found in the precavopulmonary mean pulmonary artery pressure (15 +/- 5 vs 15 +/- 6 mm Hg), transpulmonary gradient (8 +/- 4 vs 8 +/- 5 mm Hg), and left ventricular end-diastolic pressure (7 +/- 2 vs 8 +/- 3 mm Hg). One patient in the study group died from respiratory syncytial virus pneumonia while awaiting cavopulmonary shunt. Neither group had mortality from the cavopulmonary shunt. The lengths of hospital stay were comparable (8.3 +/- 3.7 vs 8.9 +/- 6.0 days). Thus, neonates with BVF area between 1 and 2 cm(2)/m(2) develop mild but hemodynamically insignificant BVF gradient by 7 months of age. This group of patients can be managed safely with relief of BVF obstruction later in infancy.

B-type natriuretic peptide in children after cardiac transplantation.

BACKGROUND: The normal B-type natriuretic peptide (BNP) concentration and the significance of increased BNP concentration in children after orthotopic heart transplant (OHT) remain unknown. We sought to determine plasma BNP concentrations in relation to post-transplant time and to explore factors associated with increased BNP in pediatric OHT recipients. METHODS: We obtained plasma BNP concentrations in 44 pediatric patients at 1 to 171 months after OHT. All patients underwent endomyocardial biopsies and echocardiography. We analyzed the association between BNP and post-transplant time, as well as the association between BNP concentration and left ventricular end-diastolic dimension (LVEDD) after transplantation. RESULTS: The age of study patients ranged from 0.9 to 21.2 years (mean, 11.4 +/- 6.2 years; median, 10.5 years). We evaluated BNP concentrations immediately after transplantation. The mean BNP concentration decreased exponentially to 100 pg/ml by 14 weeks after OHT. Although BNP concentration relative to time after OHT varied among individuals, all patients with multiple measurements showed predictable rates of decrease. This decrease in BNP concentration was not associated with changes in LVEDD. CONCLUSIONS: Plasma BNP concentration was elevated in children after OHT and decreased exponentially in time to 100 pg/ml by 14 weeks after OHT. The decrease in BNP concentration was unrelated to left ventricular dimension.

Postoperative arrhythmia.

Postoperative arrhythmia is a major cause of morbidity and mortality after cardiac surgery for congenital heart disease. Rhythm disturbances that may be well tolerated in a normal heart often cause hemodynamic instability when they occur in the immediate postoperative period. In the face of pre-existing myocardial dysfunction resulting from preoperative pressure or volume overload, patients with congenital heart conditions are especially vulnerable to rhythm disturbances after cardiac surgery. Cardiopulmonary bypass, intraoperative injury to the conduction system and myocardium, postoperative metabolic abnormalities, electrolyte disturbances, and increased adrenergic tone in response to the stress of the surgery or inotropic agents are also known factors associated with increased risk of arrhythmia in the immediate postoperative period. Surgically related arrhythmia can also present in the late postoperative period, particularly in association with surgical incision sites and surgically induced hemodynamic abnormalities. Early and late postoperative arrhythmias are important risk factors for morbidity and mortality after surgical treatment of many forms of congenital heart disease. This review describes the incidence of the most common forms of arrhythmia and recent advances in their diagnosis and treatment.