Cardiac surgery
Professor Sir Norman Williams, Professor P. Ronan O’Connell, Professor Andrew W. McCaskie in Bailey & Love's Short Practice of Surgery, 2018
The ductus arteriosus, a normal fetal communication, facilitates the transfer of oxygenated blood from the pulmonary artery to the aorta, shunting blood away from the lungs. Normally, functional closure of the ductus occurs within a few hours of birth; it is abnormal if it persists beyond the neonatal period. The ductus closes in response to an increase in peripheral oxygen saturation and a drop in the resistance of the pulmonary circulation as the lungs expand; this causes the ductal tissue to contract through a prostaglandin inhibition mechanism. A cyclo-oxygenase inhibitor (e.g. indo- methacin) may be used therapeutically to close the ductus in the first few weeks of life. In premature babies the ductus is more likely to remain patent for longer or permanently. In the isolated case of PDA, there is a left-to-right shunt of blood, resulting in a high pulmonary blood flow. Small shunts usually cause few symptoms and signs apart from the continuous machinery murmur in the left second intercostal space. Larger ducts cause cardiac failure and can uncommonly lead to shunt reversal with cyanosis and clubbing. The diagnosis is best confirmed by echocardiography with colour flow Doppler imaging.
The Child With Suspected Congenital Heart Disease
Michael B O’Neill, Michelle Mary Mcevoy, Alf J Nicholson, Terence Stephenson, Stephanie Ryan in Diagnosing and Treating Common Problems in Paediatrics, 2017
The ductus arteriosis connects the descending aorta (distal to the origin of the left subclavian artery) to the left pulmonary artery. In the foetus, the duct allows blood to flow from the pulmonary artery into the aorta, thereby bypassing the lungs and allowing oxygenation in the placenta. A PDA is defined as persistence of the ductus arteriosus beyond 1 month of age. The ductus arteriosus normally closes in the first 72 hours after birth. Failure of the duct to close is common in premature infants with up to 50% of preterm infants under 1500 g having a PDA. Small PDAs are usually asymptomatic, whereas a large PDA causes recurrent lower respiratory infections, failure to thrive and heart failure. Examination reveals a continuous machinery murmur below the left clavicle, a hyperdynamic precordium and bounding peripheral pulses.
Pediatric Imaging in General Radiography
Christopher M. Hayre, William A. S. Cox in General Radiography, 2020
As the neonate’s lungs naturally recoil and they start to take their first few breaths, blood fills the lung capillaries and the resistance within the pulmonary vessels falls, the airways fill with air and gaseous exchange starts within the alveoli. As the umbilical cord is clamped, the peripheral blood pressure increases causing a pressure differential within the heart closing the foramen ovale: this closes permanently with the fall in maternal hormone levels that had kept this patent in the uterus (South & Isaacs, 2012). The ductus arteriosus usually closes within a few days of birth. For the term neonate with mature lungs, the recoil and entry of air into the alveoli causes surfactant to be released. This is a substance that reduces the surface tension of the alveoli and prevents them collapsing during exhalation. In the preterm infant with immature lungs this process does not occur. If there is a high risk of premature labor the mother may be given steroids from 23 weeks gestation to aid in surfactant maturation, and the preterm neonate given surfactant soon after birth. This is one occasion when the ‘four hour rule’ for a chest X-ray is not applicable, as the exogenous surfactant has to be delivered via an appropriately sited endotracheal tube.
Update on shunt closure in neonates and infants
Published in Expert Review of Cardiovascular Therapy, 2021
Karim A. Diab, Younes Boujemline, Ziyad M. Hijazi
The ductus arteriosus is a normal vascular structure in the fetus that connects the main pulmonary artery with the descending aorta or subclavian artery. It allows the right ventricle to pump the blood into the aorta, bypassing the pulmonary circulation. It typically closes within the first 2–3 weeks of life and is considered an abnormal shunt if it remains patent beyond that period. The Patent Ductus Arteriosus (PDA) occurs at an incidence of 1 in 2,000 live births in children born at term [1]. It is even more common in preterm neonates and those with Down syndrome and is actually the most common shunting lesion in premature newborns [77]. It can result in significant heart failure and increased morbidity including increased risk of intraventricular hemorrhage, necrotizing enterocolitis and chronic lung disease and prolongation of ventilator support, particularly in those high-risk infants [78–84]. Medical therapy with anti-inflammatory medications is commonly used for achieving closure of the PDA in these infants. However, this carries some risk such as renal injury, intracranial hemorrhage and intestinal perforation and can be contraindicated in some patients [85]. Surgical ligation has been commonly used when medical therapy fails. However, it is also not without risks including among other morbidities systemic hypotension, significant worsening of the patient’s pulmonary status, vocal cord paralysis, scoliosis and phrenic nerve palsy [86].
Paths of causal influence from prenatal inflammation and preterm gestation to childhood asthma symptoms
Published in Journal of Asthma, 2019
Nada Sindičić Dessardo, Elvira Mustać, Srdjan Banac, Sandro Dessardo
Placental histological examination included a minimum of three cross sections of the umbilical cord taken from its foetal and placental side, three membrane rolls, and a sample of the chorionic plate and three samples from the maternal side of the placenta. The inflammatory findings at histology were recorded and accounted for the worst area scored, according to the classification proposed by Redline [17]. Newborns were classified as having FIRS if severe HCA and funisitis were confirmed to be present [18]. Respiratory distress syndrome was defined as the need for oxygen supplementation or mechanical ventilatory support for at least 48 h. Patent ductus arteriosus was defined by clinical signs and the presence of typical echocardiographic findings. CLD of prematurity was defined as the need for mechanical ventilation or supplemental oxygen beyond 36 weeks of postconceptional age [19]. The newborns were considered to have early and/or late onset sepsis if there was either a positive culture or clinical signs of infection accompanied by concurrent antibiotic treatment for at least 7 days. Post-natal follow-up included regular visits at 6 and 12 months of age, and once a year visits following the first year of life, in order to collect additional clinical data of relevance for the study. For the purpose of the study, the criteria for the definition of ECW were the presence of three or more episodes of wheezing per year for which a bronchodilator had been prescribed [20]. The assessment of ECW prevalence was made at the age of 3 years for all the enrolled infants.
Interventional Cardiology at a Pivot Point
Published in Structural Heart, 2018
Interventional procedures have been applied for a variety of congenital heart diseases for many years. In fact, catheter closure of atrial septal defects was the first non-invasive technique directed to the treatment of structural heart disease. A variety of devices have been developed to close atrial and ventricular septal defects as well as patent ductus arteriosus. In addition, balloon dilation of pulmonic stenosis, coarctation of the aorta, and pulmonary artery stenosis have become accepted clinical procedures. Transcatheter valves are being deployed even as technological innovation continues. It is likely that such procedures will increase in the future as patients with congenital heart disease increasingly survive into adulthood. In terms of the future, perhaps the greatest growth will be in closure of the patent foramen ovale (PFO). Three recent studies in the New England Journal of Medicine and a recent meta-analysis all attested to the value of catheter closure of a patent foramen in patients with prior cryptogenic stroke or transient ischemic attack.9 Since a PFO has been found to be present in approximately 20% of the population, closure of such lesions is likely to substantially increase.