ABSTRACT
We undertook a study to describe changes in heart rate variability (HRV) postoperatively in children undergoing cardiac bypass surgery for congenital heart disease (CHD). HRV was recorded for a 1-h period preoperatively and a 24-h period postoperatively in 20 children with CHD. We found a highly significant reduction in HRV in both time and frequency domain indices compared to preoperative values, which was sustained throughout the 24-h study period. There was a negative correlation between both time and frequency domain HRV measurements and length of cardiac bypass. HRV is reduced postoperatively and correlates with cardiac bypass time. Length of cardiac bypass time may be one mechanism whereby HRV is reduced following surgery.
Subject(s)
Autonomic Nervous System/physiopathology , Coronary Artery Bypass/adverse effects , Heart Defects, Congenital/surgery , Heart Rate , Heart/innervation , Adolescent , Child , Child, Preschool , Cohort Studies , Electrocardiography, Ambulatory , Female , Fourier Analysis , Humans , Infant , Male , Postoperative Care , Preoperative Care , Time Factors , Treatment OutcomeABSTRACT
OBJECTIVE: Sildenafil (Viagra, Pfizer) is being increasingly used to treat pulmonary hypertension in children. However, there are limited data available to suggest dosage regimens. The purpose of this study was to determine the effects of escalating doses of sildenafil on hemodynamics and gas exchange in children with pulmonary hypertension because of congenital cardiac defects. DESIGN: Prospective, observational study. SETTING: Pediatric intensive care unit in a tertiary care children's hospital. PARTICIPANTS: Ten children with pulmonary hypertension because of congenital cardiac defects who were in the intensive care unit and on nitric oxide after cardiac surgery. INTERVENTION: Patients received sildenafil every 4 hours via a gastric tube in incremental doses of 0.5 mg/kg, 1 mg/kg, 1.5 mg/kg, and 2.0 mg/kg along with nitric oxide during their stay in the intensive care unit until they were extubated. Hemodynamic and arterial blood gas measurements were taken before (baseline) and 60 minutes after the administration of sildenafil. MEASUREMENTS AND MAIN RESULTS: All doses of sildenafil caused significant reduction in pulmonary artery pressure with no significant effect on systemic arterial and central venous pressures. Arterial partial pressure of oxygen was decreased after a 2.0 mg/kg dose of sildenafil but not significantly. No significant differences were found among the 4 doses. CONCLUSION: For the treatment of pulmonary hypertension in children with congenital cardiac defects, a 0.5 mg/kg dose of sildenafil every 4 hours is therapeutically as effective as a 2.0 mg/kg dose every 4 hours. However, a large dose-ranging and pharmacokinetic study of sildenafil in children with pulmonary hypertension because of congenital cardiac defects is needed to validate the safety and efficacy of the dose-range and dosing interval suggested by this study.
Subject(s)
Heart Defects, Congenital/physiopathology , Hypertension, Pulmonary/drug therapy , Hypertension, Pulmonary/physiopathology , Piperazines/administration & dosage , Pulmonary Gas Exchange/drug effects , Pulmonary Wedge Pressure/drug effects , Sulfones/administration & dosage , Vasodilator Agents/administration & dosage , Analysis of Variance , Blood Gas Analysis , Bronchodilator Agents/therapeutic use , Cardiac Surgical Procedures , Child , Child, Preschool , Dose-Response Relationship, Drug , Female , Heart Defects, Congenital/blood , Heart Defects, Congenital/complications , Heart Defects, Congenital/surgery , Heart Rate/drug effects , Humans , Hypertension, Pulmonary/blood , Hypertension, Pulmonary/etiology , Male , Nitric Oxide/therapeutic use , Phosphodiesterase Inhibitors/administration & dosage , Piperazines/pharmacology , Prospective Studies , Purines/administration & dosage , Purines/pharmacology , Research Design , Sildenafil Citrate , Sulfones/pharmacology , Treatment Outcome , United Kingdom , Vasodilator Agents/pharmacologySubject(s)
Hypertension, Pulmonary/drug therapy , Hypertension, Pulmonary/physiopathology , Piperazines/therapeutic use , Pulmonary Wedge Pressure/physiology , Vasodilator Agents/therapeutic use , 3',5'-Cyclic-GMP Phosphodiesterases/antagonists & inhibitors , Animals , Humans , Pulmonary Wedge Pressure/drug effects , Purines , Sildenafil Citrate , Sulfones , Treatment OutcomeABSTRACT
Reconstruction of the right ventricular outflow tract (RVOT) is needed in a wide variety of congenital heart diseases at the time of primary repair, or later for replacement of existing valves or conduits. Ideally, the conduit or valve needed for such reconstruction should be formed of autologous tissue that grows, resists infection, lasts for the life span of the patient, and is readily available in all sizes. Such a conduit is not available, though several alternatives have been used, none of which is without potential drawbacks. One alternative--the Contegra bovine jugular vein conduit (Medtronic, Inc., Minneapolis, MN, USA)--was introduced in 1999 and has gained widespread application, with increasing enthusiasm for its use. The Contegra conduit consists of a bovine jugular vein with an incorporated trileaflet valve. The conduit tissue is extremely pliable and offers optimal conditions for surgical handling. Moreover, the proximal tubular segment allows construction of the proximal anastomosis to the right ventricle, without the use of additional material. Increasingly, experience with the Contegra conduit is being published; hence, a literature search was conducted to evaluate available evidence on current use of the device in pediatric RVOT reconstruction.
