Improvement in noninvasive electrophysiologic findings in children after transcatheter atrial septal defect closure.

To evaluate whether transcatheter closure of secundum atrial septal defects (ASD) affected noninvasive electrophysiologic variables in children, we reviewed the pre-procedural and 1-year postprocedural electrocardiograms and Holter recordings of 18 consecutive children referred for ASD closure. Patients included in the study were a mean of 5.0 years old (SD 1.1) and weighed a mean of 17.9 kg (SD 4.1). ASDs had a mean diameter of 14.0 mm (SD 2.4) and average shunt ratio (pulmonary-to-systemic flow) of 2.1:1. One year after occluder device placement, 9 children (50%) had detectable residual shunts by transthoracic echocardiograms, but only 2 (11%) had shunts that were felt to be possibly significant. One or more fractured occluder legs were noted by chest roentgenogram in 15 patients (83%). Electrocardiograms at follow-up demonstrated improvement in right ventricular dilation in 4 of 7 patients, right atrial enlargement in 3 of 4 patients, and 1 degree atrioventricular block in 2 of 3 patients. Holter recordings showed a decreased incidence of accelerated atrial rhythm in 3 of 7 patients, prolonged junctional escape rhythm in 2 of 2 patients, and premature atrial contractions in 2 of 2 patients. No finding correlated with patient age, defect or occluder diameter, occluder leg fracture(s), or residual defects. These improvements in electrophysiologic abnormalities compare favorably with changes seen 1 year after surgical closure. In conclusion, placement of a transcatheter ASD device in children diminishes noninvasive electrophysiologic abnormalities at 1-year follow-up. By relieving hemodynamic stress caused by an ASD in childhood, a transcatheter device may prevent arrhythmia disturbance later in life.

Transcatheter occlusion of patent ductus arteriosus in adults.

This study examines whether transcatheter closure of a patent ductus arteriosus (PDA) using a Rashkind PDA occluder device is safe and effective in adults, or if adults have complications not sited in children owing to prolonged aorticopulmonary communication, high surgical risks or calcified PDAs. Fifteen patients aged 22 to 76 years (mean 42 +/- 14) were referred for transcatheter PDA occlusion. Exercise intolerance was the most frequent clinical manifestation. Eleven of 15 patients had surgical risk factors that included left ventricular failure (n = 10), biventricular failure (n = 1), elevated pulmonary pressures (n = 1), and a calcified PDA (n = 5). Twelve millimeter devices were placed in 4 PDAs < or = 3 mm in diameter; 17 mm devices were placed in 11 PDAs 3 to 6 mm in diameter. Seven (47%) were occluded angiographically shortly after device placement; another 5 PDAs (33%) were occluded echocardiographically within 24 hours of the procedure. Completed occlusion in this time interval was more likely to occur in PDAs < 5 mm in diameter (p = 0.0009). Of the 3 remaining PDAs with follow-up ranging from 9 to 38 months, 2 have demonstrated gradual diminution of shunting and have trivial leaks by color/Doppler flow. The other patient with a residual PDA has no ductal flow after placement of a second device. No complications related to device implantation or closure of the PDA occurred in any patient. No complications were reported in the follow-up patients who received evaluation (14 of 15 patients; range 1 to 38 months).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative electron microscopic study of bovine, porcine and human parietal pericardium, as materials for cardiac valve bioprostheses.

Light, scanning and transmission electron microscopy were used in the comparison of bovine, porcine and human parietal pericardium. Bovine pericardium is widely used for heart valve bioprosthesis, is thicker than the other two, and has more coarse connective tissue fiber components, whereas porcine pericardium possesses relatively larger quantities of fat cells in regular layers. Human tissue is thinner than either the bovine or porcine parietal pericardium and its mesothelium seems less delicate. The human tissue, being thinner, may provide a source of materials for valves with significant hemodynamic characteristics. Such material might be used to produce small diameter valves directed towards younger patients. Though the literature does not mention its usage, porcine pericardium is of intermediate thickness and it too may serve in the future as a construction material for valve bioprostheses.

Pretreatment of formula with sodium polystyrene sulfonate to reduce dietary potassium intake.

Sodium polystyrene sulfonate (SPSS) is commonly administered for the acute and chronic treatment of hyperkalemia. Its oral intake is complicated by poor compliance due to multifaceted reasons. We therefore analyzed a method of reducing potassium (K) in formula by pretreatment with SPSS. If effective, this would bypass complications of enterally administered SPSS and provide low-K formula. Thirteen formulas and nutritional supplements were pretreated with SPSS to determine if one could bind K and provide formulas with decreased K contents. Using an SPSS concentration of 1 g/l mEq K in the formula, 62 +/- 2.6% (P less than 0.01, mean +/- SEM) of the K was removed in 30 min, while the sodium (Na) concentration was increased by 234 +/- 37% (P less than 0.01). Analysis suggests that the disproportionate increase in Na is due to exchange for calcium (Ca) and magnesium (Mg), interaction with proteins, and Na suspended with SPSS in the formula. Thus, SPSS pretreatment of formula is an effective method of making low-K formula, but the increase in Na exceeds the K reduction. Attention to possible complications of increased Na intake as well as decreased Ca and Mg intake is warranted.