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Biomedical subjects

L T Mahoney

Publications and source records attributed to L T Mahoney.

43 records · Page 3Linked to original sources
PubMed1985

The newborn transitional circulation: a two-dimensional Doppler echocardiographic study.

To characterize changes in circulation after birth, 11 normal full-term infants were examined with two-dimensional and pulsed Doppler echocardiography. The initial examination was performed within 10 hours after delivery and serially for 3 days. Retrograde diastolic pulmonary artery velocities, which are evidence for a patent ductus arteriosus, were detected in 10 infants (91%) on day 1, in 2 (18%) on day 2 and in none on day 3. Retrograde systolic descending aortic velocities, which are evidence of flow from the aorta into the ductus arteriosus, were observed in 10 infants (91%) on day 1, 9 (81%) on day 2 and 7 (64%) on day 3. Persistence of the retrograde systolic velocity in the descending aorta in the absence of retrograde diastolic velocity in the pulmonary artery is consistent with physiologic ductal closure beginning near the pulmonary artery end of the ductus arteriosus. Localized turbulent retrograde systolic flow, proximal to the septal leaflet of the tricuspid valve and consistent with tricuspid insufficiency, was detected in six patients (55%) on day 1, in eight (73%) on day 2 and in seven (64%) on day 3. Thus, tricuspid insufficiency appears to be a frequent observation in healthy newborns. Normal Doppler velocities in the great arteries and across the tricuspid and mitral valves of newborns up to 3 days of age are presented. These normal measures of intracardiac flow velocities may be used for comparison to identify abnormal flow profiles in newborns with congenital heart defects.

Blood Circulation↗
PubMed1982

Spontaneous closure of a coronary artery fistula in childhood.

An infant with a symptomatic coronary artery fistula, documented by angiography, is presented. By age 5 years, clinical evidence of the fistula was no longer present. Repeat cardiac catheterization confirmed spontaneous closure of the coronary artery fistula. More information regarding the natural history of a coronary artery fistula is required before an elective surgical approach can be recommended in all asymptomatic children.

Cardiac Catheterization↗
PubMed1982

Forearm vascular resistance in the upper and lower quintiles of blood pressure in adolescent boys: The Muscatine Study.

Nineteen 16 year old white boys whose systolic blood pressures were in the upper (r = 9) and lowest (r = 10) quintile of the distribution in two school surveys in 1975 and 1977 were selected. In 1979 forearm blood flow, blood pressure and heart rate were measured at rest, and during peak reactive hyperemia. Minimal forearm vascular resistance during peak reactive hyperemia was used to assess the structural contribution to vascular resistance. At rest the high quintile group again had significantly higher blood pressures than the low quintile group but their forearm vascular resistance was not significantly different. The high quintile group showed significantly higher minimal forearm vascular resistance at peak reactive hyperemia. The latter observation suggests that there is a difference in the structural contribution to forearm vascular resistance in adolescents with blood pressure in the upper versus lower quintile of the distribution.

Adolescent↗
PubMed1979

Measurement criteria for group echocardiographic studies.

This study reports the reproducibility achieved both within an observer and between observers measuring left heart echocardiographic dimensions using standard measurement criteria in school age children. These criteria define acceptable interfaces as: 1) a single dominant line; 2) continuity at the point of measurement of at least 5 mm in length; and 3) display of specific motion characteristics for the cardiac structure to be measured. The within observer intraclass correlation coefficient for interventricular septum, diastolic dimension, systolic dimension, left ventricular posterior wall, left atrium and aorta averaged 0.94 (range 0.87--0.98). The coefficient of variation averaged 3.6% (range 2--7.5%). The least reproducible dimension was left ventricular posterior wall. The day-to-day variability within a single subject of echocardiographic determined cardiac dimensions was small for all measurements. The standard deviation of error for all variables was no more than 0.3 mm. A system using screening criteria and standardized measurement techniques can provide the degree of precision necessary to begin investigating echocardiographic differences in group studies.

Adolescent↗
PubMedDate not supplied

Hemodynamic responses to nitrous oxide during inhalation anesthesia in pediatric patients.

STUDY OBJECTIVE: To measure the hemodynamic changes produced by nitrous oxide (N2O) during halothane and isoflurane anesthesia in infants and children. DESIGN: A repeated measures design in two groups of infants and small children. SETTING: Operating rooms at a university hospital. PATIENTS: Nineteen healthy unmedicated infants and small children (mean age 12 months) who required elective surgery. INTERVENTIONS: Prior to anesthesia induction, cardiovascular measurements were recorded using pulsed Doppler and two-dimensional echocardiography. Following anesthesia induction with halothane (n = 10) or isoflurane (n = 9) in oxygen (O2) and air, anesthetic measures were stabilized at 1.0 minimum alveolar concentration (MAC) and cardiovascular measures were repeated. After 30% N2O was added to the 1.0 MAC anesthetic concentration, a third set of cardiovascular measurements was recorded. A final cardiovascular data set was measured 5 minutes following an increase in N2O concentration to 60%. MEASUREMENTS AND MAIN RESULTS: Mean arterial pressure (MAP), cardiac index (CI), stroke volume (SV), and ejection fraction (EF) decreased similarly and significantly at 1.0 MAC halothane and isoflurane. Heart rate (HR) increased during isoflurane anesthesia but decreased during halothane anesthesia. The addition of N2O resulted in a decrease in HR, CI, and MAP when compared to 1.0 MAC levels of halothane or isoflurane; however, SV and EF were not significantly changed from levels measured during 1.0 MAC halothane or isoflurane. CONCLUSIONS: The addition of N2O to halothane and isoflurane anesthesia in infants and children decreased HR. This decrease led to a decrease in cardiac output (CO). Unlike with adults, N2O did not produce cardiovascular signs of sympathetic stimulation in infants and children.

Anesthesia, Inhalation↗
PubMedDate not supplied

Congenital heart surgery: a five year study.

The practice of surgery for congenital heart disease has undergone a major evolution in the past few years. Technical advances, the introduction of operative procedures, and a change in philosophy relating to the proper timing of surgical intervention are the major factors responsible for this change. To document our experience, a comprehensive review of all surgery performed for congenital heart disease at the University of Colorado Health Sciences Center during the last five years was conducted.

Cardiac Surgical Procedures↗