Cardiovascular Stressors and Adaptation
Common Cardiovascular Disorders in Children Congenital Heart Defects • Congestive Heart Failure Acquired Heart Disease
Review of Normal Circulation
How to Understand Congenital Defects Think of blood as: • Red highly O2 saturated • Blue unsaturated • Purple medium O2 saturated (mixed) • Lavender- reduced volume of medium O2 saturated (mixed) • Pink Low O2 saturated • Light Blue Reduced volume of unsaturated
Fetal Shunts ductus venosus : accessory (extra) vein, carries oxygenated blood from umbilical vein into lower venous system foramen ovale : shunts mixed blood from right atrium to left atrium (hole in the atrial septum) ductus arteriosus : accessory (extra) artery, shunts mixed blood away from lungs to descending aorta
How does the fetus receive sufficient oxygen from the maternal blood supply? Fetal hemoglobin carries 20-30% more oxygen than maternal hemoglobin Fetal hemoglobin concentration is 50% greater than mother’s Fetal heart rate 120-160bpm (increases cardiac output)
What happens to the shunts after birth?
Transition from intrauterine to extrauterine life Cord is clamped, neonate initiated respirations O2 levels rise = greater pressure in the left atrium, decreased pressure in the right atrium leading to an immediate closure of the foramen ovale
Transition from intrauterine to extrauterine life After O2 circulates systemically, over 24 hours, the pressure in the left ventricle will become greater than the pulmonary artery and closes the ductus arterosis The absent flow of blood through the umbilicus gradually closes the ductus venosus over 12 hr to 2 weeks
Cardiac Defects Either: Ductal closure failure (no structural abnormality) Structural abnormality
Diagnosis Assessment findings Results of diagnostic testing • Cardiac Catherization
Cardiac Catheterization Primary method to measure extent of cardiac disease in children Shows type and severity of the CHD Insert tiny catheter through an artery in arm, leg or neck into the heart Take blood samples and measure pressure, measure o2 saturation, and as an intervention Sedation or anesthesia Outpatient vs Hospital
Cardiac Catheterization-Post Op Monitor closely (cardiac monitor, continuous pulse ox) VS q 15 Assess dressing at insertion site for infection, hematoma Dressing must remain dry for 1st 48-72 hrs No blood drawn from extremity used Palpate a pulse distal to the dressing to assure blood flow to extremity is not obstructed: keep extremity straight for 48 hrs after procedure
If Congenital Defect is suspected or confirmed, Intervention is Important to Prevent CHF
Congestive Heart Failure Heart doesn’t pump blood well enough –can not provide adequate cardiac output due to impaired myocardial contractility Causes in children: • Defects • Acquired heart disease • Infections
Congestive Heart Failure Most common cause in children is
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- Fall '12
- Congenital heart defect, Ductus Arteriosus