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Biomedical subjects

M H Lees

Publications and source records attributed to M H Lees.

At least 19 recordsLinked to original sources
PubMed1987

Utility of a screening examination of the fetal cardiac position and four chambers during obstetric sonography.

The findings were reviewed for approximately 6,700 high- and low-risk obstetric sonograms that included screening imaging of the fetal cardiac position and four chambers as part of a brief fetal anatomy survey. This screening examination identified 12 major cardiac malformations, 3 unusual cardiomegalies and 12 abnormal positions caused by noncardiac abnormalities. Most of these abnormalities probably would not have been identified without the screening examination. Also, the finding of an abnormal fetal cardiac position was often the main indication of a noncardiac abnormality, such as a diaphragmatic hernia. Screening imaging of the fetal cardiac position and four chambers appears to be a productive addition to the fetal anatomy survey for our particular mix of high- and low-risk patients.

Female↗
PubMed1982

Chloral hydrate and the carbon dioxide chemoreceptor response: a study of puppies and infants.

CO2 chemoreceptor function was assessed during natural sleep and following the administration of 100 mg/kg of chloral hydrate to 26 puppies. With chloral hydrate-induced sleep, there were no significant changes in ventilation or in CO2 chemoreceptor response. The ventilation and CO2 chemoreceptor response of a group of infants in natural sleep were compared with those of a group receiving 50 mg/kg of chloral hydrate. Tidal volume O2 consumption, and CO2 elimination were slightly higher in the group given chloral hydrate. There was no difference in the CO2 chemoreceptor response. The proportion of time spent in rapid eye movement (REM) and non-rapid eye movement (NREM) sleep in chloral hydrate-induced sleep was similar to that occurring in natural sleep. Use of chloral hydrate stabilizes O2 consumption sleep. Use of chloral hydrate stabilizes O2 consumption and CO2 production, and it greatly facilitates the assessment of chemoreceptor function in infants. The CO2 chemoreceptor response appears not to be altered in puppies or infants.

Animals↗
PubMed1982

Common pulmonary vein atresia: Importance of immediate recognition and surgical intervention.

Common pulmonary vein atresia is a rare congenital anomaly; all four pulmonary veins drain into a common dilated chamber with no direct connections to the heart or systemic venous system. Since its first description in 1962, 16 cases have been reported. Only four patients were surgically managed and none survived. This communication presents the seventeenth reported case of common pulmonary vein atresia and the only patient whose anomaly was suspected early enough to demand immediate surgical management, with gratifying long-term success. The literature on the subject is reviewed and common features of the anomaly are emphasized to facilitate precise diagnosis, so that a futile search for a nonexistent communicating vein is avoided at the time of operation. This approach has led to the first successful surgical management of this otherwise fatal lesion.

Heart Atria↗
PubMed1980

Ventilatory response to carbon dioxide of infants following chronic prenatal methadone exposure.

Nine infants chronically exposed to methadone in utero were studied from birth to 7 weeks of age (66 studies). The maternal dose of methadone/HCl during the third trimester ranged from 14 to 70 mg orally once a day. The mean (range) of serum methadone t 1/2 in the neonates was 53 hours (22 to 113). In the first four days of life the methadone-exposed infants had a significantly (P less than 0.005) decreased sensitivity to carbon dioxide compared to control infants as measured by the slope of the ventilatory response curve. The mean slope +/- SD for the methadone-exposed infants, 10.4 +/- 7.7 ml/minute/kg mm Hg, was one third that of the control group (30.0 +/- 9.9 ml/minute/kg/mm Hg). Total ventilation, respiratory frequency, oxygen consumption, and end-tidal PCO2 were not significantly different in the two groups. The depressed ventilatory response to carbon dioxide persisted for an average of 15 days and lasted as long as 31 days in one infant. The time required to achieve a normal slope was not related to the size of the maternal methadone dose, to neonatal serum methadone t 1/2, or to the severity of and therapy for methadone withdrawal. If this abnormality in sensitivity to carbon dioxide persists beyond the neonatal period in some infants, it may contribute to the increased incidence of the sudden infant death syndrome among infants exposed to methadone in utero. Measurement of the ventilatory response to carbon dioxide may be clinically useful to determine which of these infants are at risk for SIDS.

Carbon Dioxide↗
PubMed1976

Percutaneous cardiac catheterization and atrial balloon septostomy in pediatrics.

Between November, 1971, and July, 1975, 688 patients ranging in age from six hours to 21 years have undergone percutaneous transfemoral venous and/or arterial catheterization at the University of Oregon Health Sciences Center. This represents 93% of all venous catheterizations of the right side of the heart and 97% of all arterial catheterizations of the left side of the heart in the pediatric age range. One hundred and ninety-five patients (29% of the group) weighed 5 kg or less and 133 (20% of the group) were neonates. There were virtually no complications following the venous studies. The complication rate following percutaneous arterial studies is lower than is the reported experience with cut-down arteriotomies. Long-term survival following percutaneous atrial balloon septostomy in D-transposition of the great arteries was comparable to that following cut-down balloon septostomy. The ease of accomplishment, significantly lower complication rate, and successful accomplishment of atrial balloon septostomy prompt us to advocate that the percutaneous technique of cardiac catheterization be extended to include the neonate and young infant who weighsless than 5 kg.

Adolescent↗
PubMed1976

Aortico-left ventricular tunnel. Recognition and repair in infancy.

An infant with an aortico-left ventricular tunnel underwent surgery at the age of five months. There was clinical and electrocardiographic improvement, and postoperative cardiac catheterization demonstrated obliteration of the aortic end of the tunnel, normalization of systemic pulse pressure, mild residual aortic valvular insufficiency, and a decrease in the left ventricular end-diastolic volume index. Early surgery may limit the progression of aortic valvular insufficiency secondary to turbulent aortic-root blood flow.

Angiocardiography↗
PubMed1975

Uterine contractility and regional blood flow responses to oxytocin and prostaglandin E2 in pregnant rhesus monkeys.

The effects of oxytocin and prostaglandin E2 (PGE2) infusions on regional blood flow (measured by radioactive microspheres) and myometrial contractility were studied in 18 pregnant rhesus monkeys near term. We observed no significant differences between PGE2 and oxytocin in cardiac output, hemodynamics, or uterine activity. Their effects on the regional distribution of systemic blood flow were similar although the gastrointestinal tract received an increased percentage of cardiac output after PGE2. A relative placental ischemia, together with a myometrial hyperemia, was observed during labor. Uterine contraction produced a large reduction (average 73 per cent) in placental blood flow whereas myometrial blood flow was maintained or sometimes increased. A significant negative correlation was observed between intra-amniotic pressure and placental blood flow. During uterine relaxation, placental flow partially recovered whereas myometrial flow nearly doubled the prelabor values. We conclude that (1) in the dose ranges studied, oxytocin and PGE2 produce similar effects on myometrial contractility and uteroplacental blood flow, and (2) the vascular beds of the placenta and myometrium respond differently to labor of moderate intensity.

Amniotic Fluid↗
PubMed1975

Postoperative hemodynamic and electrophysiologic evaluation of the interatrial baffle procedure.

Hemodynamic and electrophysiologic studies were performed in 11 children with dextrotransposition of the great arteries an average of 26 months after the interatrial baffle procedure and, in 2 patients, additional closure of a ventricular septal defect. All children are clinically well. Right to left shunts ranging from 28 to 63 percent of systemic blood flow were found at the superior vena caval-baffle junction in four children. The superior vena caval-baffle gradient averaged 7 mm Hg (range 0 to 22). Right ventricular stroke work index averaged 39 g-m/beat per m2 and right ventricular end-diastolic pressure 9 mm Hg. These values were not significantly different from the values for the systemic left ventricle in a comparable group of normal children (average left ventricular stroke work index 45 g-m/beat per m2 and average left ventricular end-diastolic pressure 8 mm Hg). Cardiac index, heart rate and arteriovenous oxygen difference were also normal. No child has complete heart block. His bundle recording demonstrated normal H-V intervals (range 27 to 40 msec); 4 of the 11 had a prolonged A-H interval. Left ventricular systolic pressure was less than 40 mm Hg in all but two children who had significant subpulmonary stenosis. Pulmonary vascular resistance averaged 1.9 units and was decreased in all children. We conclude that up to 37 months postoperatively, despite some residual abnormalities, the clinical and hemodynamic condition of these children is excellent.

Angiocardiography↗