Intravascular ultrasound can assist angiographic assessment of coarctation of the aorta.
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Adolescent↗
Biomedical subjects
M D Reller
Publications and source records attributed to M D Reller.
Arteriohepatic dysplasia and cardiovascular malformations.
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Abnormalities, Multiple↗
Atrial myocardial blood flow during acute right ventricular pressure load and adenosine infusion in late gestation fetal sheep.
The purpose of this study was to investigate atrial myocardial blood flow in the fetus under conditions of acute right ventricular pressure load and adenosine infusion. Late gestation fetal sheep were instrumented for acute right ventricular pressure loading or adenosine infusion, and regional myocardial blood flow was measured at rest and under experimental conditions with radiolabeled microspheres and standard reference sample technique. Resting myocardial blood flow to the atria was less than half of ventricular flow per gram tissue. During the maximum tolerated pulmonary artery pressure load, right atrial peak systolic pressure rose significantly, and atrial blood flow increased 3-fold. The percentage of total myocardial blood flow received by the right atrium during maximal pressure loading increased from 4.3 +/- 1.4% to 5.9 +/- 1.6%, p < 0.05. Adenosine infusion was associated with a 4-fold increase in atrial myocardial blood flow and a 3-fold increase in ventricular and septal blood flow. The percentage of total myocardial blood flow to both atria also increased with adenosine infusion (right atrium, 3.8 +/- 0.4% to 5.4 +/- 1.3%, and left atrium, 4.2 +/- 0.8% to 6.9 +/- 2.0%, p < 0.05). We conclude the following: 1) at rest, fetal atrial myocardial blood flow is less than one half of ventricular myocardial blood flow per gram tissue; 2) fetal atrial blood flow increases more than ventricular blood flow with acute right ventricular pressure load or adenosine infusion; and 3) these data suggest that fetal atrial blood flow is regulated independently from ventricular blood flow and may be influenced by atrial work.
Adenosine↗
Effect of atrial natriuretic peptide on vascular permeation in the ovine fetus.
To study the effect of atrial natriuretic peptide (ANP) on vascular permeation of albumin in the fetus, ANP (167-600 ng/min) was infused into eight ovine fetuses and saline vehicle was infused into eight twin controls (gestational age 127 +/- 3 d) over a 50-min period. Using two different radiolabeled albumin markers, we determined the tissue to blood isotope ratio (TBIR), an index of albumin permeation, and the albumin clearance. Although ANP had no hemodynamic effect, a marked increase in the hematocrit was observed in ANP-infused fetuses compared with initial values (0.37 +/- 0.04 vs 0.42 +/- 0.04, p < 0.005) but was unchanged in the twin fetuses receiving saline vehicle (0.35 +/- 0.03 versus 0.35 +/- 0.02). TBIR and albumin permeation were increased in combined tissues of ANP-infused fetuses compared with saline controls (TBIR: 1.49 +/- 0.58 versus 1.29 +/- 0.3, p < 0.001; albumin clearance: 1091 +/- 1279 versus 827 +/- 1464 nL/g/min, p < 0.01). In individual tissues, TBIR was significantly increased in skin (2.88 +/- 0.67 versus 1.55 +/- 0.35, p < 0.02), muscle (1.6 +/- 0.27 versus 1.24 +/- 0.26, p < 0.02), adrenal (1.33 +/- 0.10 versus 1.13 +/- 0.15, p < 0.02), bone (1.67 +/- 0.45 versus 1.20 +/- 0.40, p < 0.02), kidney (1.52 +/- 0.25 versus 1.24 +/- 0.26, p < 0.03), and gut (1.69 +/- 0.20 versus 1.39 +/- 0.34, p < 0.03).(ABSTRACT TRUNCATED AT 250 WORDS)
Albumins↗
Effect of patent ductus arteriosus on Doppler-derived right ventricular systolic time intervals.
Right ventricular systolic time intervals (RVSTI) and noninvasive Doppler-derived pulmonary blood flow were measured before and after surgical ductus ligation in 18 otherwise healthy infants and children who were older than 3 months of age. Right ventricular preejection period (PEP) and the ratio of preejection period and right ventricular ejection time (PEP/RVET), both corrected or uncorrected for heart rate, decreased significantly following surgery (PEP 71 +/- 14 vs. 50 +/- 13, p < 0.001 and PEP/RVET 0.29 +/- 0.06 vs. 0.21 +/- 0.05, p < 0.001). The volume of pulmonary blood flow correlated with PEP/RVET (r = 0.48, p = 0.003). The magnitude of the change in pulmonary blood flow correlated with the change in PEP/RVET (r divided by 0.56, p = 0.016). The velocity of circumferential fiber shortening (VCFc) increased after surgery, but not significantly. We speculate that patent ductus arteriosus has a similar effect on right ventricular performance when other congenital heart defects are present.
Blood Flow Velocity↗
Review of studies evaluating ductal patency in the premature infant.
A series of investigations has been performed to assess the timing of physiologic closure of the ductus arteriosus in premature infants with and without respiratory distress syndrome. The data from these studies emphasize the concept of physiologic ductal patency and give normative data for expected closure rates through the fourth day of life. On the basis of these data, patency on or beyond the fourth day of life is abnormal irrespective of gestational age, and prematurity, in the absence of respiratory distress syndrome, is not a risk factor for persistent patent ductus arteriosus. We also found that persistent patent ductus arteriosus in larger premature infants (> or = 30 weeks of gestation) with respiratory distress syndrome is relatively uncommon. Last, ductal patency was evaluated in a group of low birth weight infants with severe respiratory distress syndrome in a randomized, double-blind trial of exogenous surfactant administration. We concluded that the beneficial effects of exogenous surfactant are not associated with either a greater clinical need for indomethacin or any increased risk of delayed closure of the ductus arteriosus.
Ductus Arteriosus, Patent↗
Progressive pulmonary stenosis in the fetus: two case reports.
Fetal echocardiography is a helpful tool in diagnosing and following the natural history of fetuses with congenital heart disease. This report describes two fetuses with complex congenital heart disease that developed progressive pulmonary stenosis in utero. On fetal echocardiogram, one of the fetuses had tetralogy of Fallot and the other had a single ventricle. Both fetuses, when followed serially by fetal echocardiography, showed pulmonary stenosis that progressed in severity. These findings confirm that certain cardiac defects progress in severity in utero.
Adult↗
Maximal myocardial blood flow is enhanced by chronic hypoxemia in late gestation fetal sheep.
The measurement of maximal myocardial blood flow gives information about the total cross-sectional area of the coronary resistance vessels. During a continuous left atrial infusion of adenosine (60 micrograms.kg-1.min-1), maximal myocardial blood flow was measured in 4 fetuses hypoxemic for a minimum of 5-8 days (pH = 7.33 +/- 0.01, arterial PCO2 = 49.8 +/- 4.2 Torr, arterial PO2 = 16.1 +/- 1.3 Torr, and arterial concentration of O2 = 5.3 +/- 1.2 ml/dl). These data were compared with an identically instrumented group of normoxemic fetuses (n = 7) following the same study protocol (pH = 7.38 +/- 0.02, arterial PCO2 = 43.1 +/- 3.8 Torr, arterial PO2 = 19.8 +/- 2.0 Torr, and arterial concentration of O2 = 7.9 +/- 1.0 ml/dl) (P < 0.05). At comparable arterial pressures, the maximal myocardial flow (ml.min-1.100 g tissue-1) for hypoxemic vs. normoxemic fetuses was 974 +/- 273 and 630 +/- 181 for the total myocardium, 986 +/- 367 and 602 +/- 192 for the left ventricular free wall, 1,025 +/- 346 and 614 +/- 178 for the septum, and 1,231 +/- 274 and 757 +/- 269 for the right ventricular free wall, respectively (P < 0.01). These data suggest that hypoxemia in the fetus can significantly alter the coronary vascular bed, which, if confirmed, would represent an important adaptation in the developing fetus.
Animals↗
Severe right ventricular pressure loading in fetal sheep augments global myocardial blood flow to submaximal levels.
BACKGROUND: It has previously been shown that the fetal right ventricle (RV) is sensitive to changes in arterial pressure and that its stroke volume is significantly reduced with acute increases in pulmonary arterial pressure. However, the myocardial blood flow (MBF) response to increases in pulmonary arterial pressure have not been investigated in the fetus. METHODS AND RESULTS: To assess whether the RV afterload sensitivity to arterial pressure is associated with limitation in MBF, seven fetal lambs were instrumented at 130 days of gestation with a pulmonary arterial occluder and intravascular catheters. RV stroke volume was measured by an electromagnetic flow probe and MBF by 15-microns labeled microspheres. MBF was determined at baseline and during incremental increases in pulmonary arterial pressure. Maximal MBF was determined in seven additional fetuses during adenosine infusion. The highest tolerated pressure was associated with a 50% reduction in RV stroke volume. The highest pulmonary arterial occlusion pressure resulted in a doubling of MBF to all regions of the heart (266 +/- 99 to 504 +/- 158, 193 +/- 69 to 387 +/- 100, and 171 +/- 66 to 338 +/- 134 ml/min/100 g for the RV, septum, and left ventricle, respectively). The best correlation for increases in both RV and global MBF was the RV heart rate-systolic pulmonary pressure product. Adenosine infusion was associated with a threefold increase in global MBF that was significantly greater than the MBF achieved during pulmonary arterial occlusion. CONCLUSIONS: The fetal RV sensitivity to acute pressure loading is not associated with limitation of MBF. The fetal myocardium has a remarkable flow reserve that allows for preservation of function during acute increases in arterial pressure.
Adenosine↗
Ductal patency in neonates with respiratory distress syndrome. A randomized surfactant trial.
The purpose of this study was to evaluate in a controlled study the effect of exogenous surfactant on various manifestations of ductal patency. Premature infants with respiratory distress syndrome were randomized to receive surfactant (Survanta) (n = 22) or air (n = 14). In neonates receiving surfactant, there was a greater tendency for an audible murmur to develop (13 of 22 vs four of 14). In spite of this, the clinical use of indomethacin was similar for the two groups, 10 (45%) of 22 vs six (43%) of 14. Excluding neonates given indomethacin early, a comparable number of surfactant-treated neonates (9/17 [53%]) vs control neonates (6/12 [50%]) demonstrated spontaneous closure of the ductus within a physiologic time frame (on or before day 4). For the gestational ages studied, the beneficial effects of exogenous surfactant were not associated with either an increased risk for delayed closure of the ductus arteriosus or a greater incidence of indomethacin usage. Utilization of exogenous surfactant does not appear to have an adverse impact on ductal patency.
Ductus Arteriosus, Patent↗
Truncus arteriosus associated with mitral atresia and a hypoplastic left ventricle.
The association of truncus arteriosus with congenital left heart abnormalities is rare. We describe a case of truncus arteriosus associated with mitral atresia and a hypoplastic left ventricle. In 11 other patients diagnosed with truncus arteriosus, none had left heart hypoplasia. Despite the truncal root being primarily or entirely committed to the right ventricle, more right than left heart abnormalities have been found. This is in contrast to double-outlet right ventricle in which left heart abnormalities are more often associated.
Female↗
Timing of ductal closure in very low birth weight premature infants without respiratory distress.
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Ductus Arteriosus↗
The timing of spontaneous closure of the ductus arteriosus in infants with respiratory distress syndrome.
Previous studies evaluating the incidence of patent ductus arteriosus have not made a distinction between physiologic ductal patency and abnormally persistent ductus arteriosus. However, it has recently been shown that healthy premature infants without respiratory distress syndrome (RDS) undergo spontaneous closure of the ductus arteriosus in the first 4 days of life at times comparable to full-term infants. Thus, ductal patency within this time frame would appear to be physiologic. Although sick premature infants are well recognized to be at risk for ductal shunting, the purpose of this investigation was to evaluate systematically the actual impact that RDS has on duration of ductal shunting by assessing the timing of spontaneous functional closure. The presence of ductal shunting was evaluated using echocardiographic color flow Doppler techniques. Thirty-six premature infants (30 to 37 weeks gestational age) were evaluated. By the fourth day of life, only 4 of 36 (11.1%) of the infants continued to have evidence of ductal patency. The remainder of the infants underwent spontaneous functional closure of the ductus arteriosus at times comparable to healthy infants without RDS. For most infants greater than or equal to 30 weeks gestation, uncomplicated RDS does not alter the usual timing of functional ductal closure.
Ductus Arteriosus, Patent↗
Diagnosis of coronary artery dehiscence and pseudoaneurysm formation in postoperative Marfan patient by color flow Doppler echocardiography.
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Adult↗
The effect of acute hypoxaemia on ventricular function during beta-adrenergic and cholinergic blockade in the fetal sheep.
The effect of acute hypoxaemia on right and left ventricular function was investigated in 8 fetal sheep (137-140 days gestation). Fetuses were instrumented with electromagnetic flow sensors on the ascending aorta and the main pulmonary artery. After 8 days recovery, hypoxaemia was achieved by reducing the maternal ewe's inspired O2 concentration to 13.1 +/- 1.5%. Control and hypoxaemic arterial blood values were pH 7.37 +/- 0.04 (SD) and 7.35 +/- 0.06, PCO2 48.0 +/- 2.8 and 47.6 +/- 5.1 mmHg, PO2 19.9 +/- 2.2 and 11.4 +/- 1.5 mmHg, haematocrit 37.5 +/- 1.2 and 39.5 +/- 2.2, respectively. Arterial pressure increased insignificantly with acute hypoxaemia (50.2 +/- 3.9 to 53.6 +/- 8.1 mmHg). Left and right ventricular performance was assessed by generating biventricular function curves relating stroke volume to mean atrial pressure. All function curves were composed of steep ascending and plateau limbs that intersected at a breakpoint. Comparing control and hypoxaemia function curves, the left ventricular stroke volume breakpoints were 0.79 +/- 0.20 and 0.78 +/- 0.21 ml/kg, respectively, while the right ventricular stroke volume breakpoints were 0.99 +/- 0.11 and 0.88 +/- 0.21 ml/kg (n.s.). In 4 fetuses, acute hypoxaemia was associated with significant increases in arterial blood pressure (P less than 0.05). In these fetuses, the right ventricular function curve was shifted significantly downward compared to the control right ventricular curve. When nitroprusside was given to these hypertensive fetuses to return blood pressure to control levels, the right ventricular function curve returned to baseline. We conclude that even under conditions of extreme hypoxaemia, ventricular function is well preserved in the normotensive fetal sheep. However, when increases in arterial pressure also accompany hypoxaemia, detectable changes in right ventricular function can be accounted for by changes in arterial pressure.
Animals↗
Fetal atrial septal aneurysm: a cause of fetal atrial arrhythmias.
Atrial arrhythmias are commonly found during fetal echocardiography performed during pregnancy to evaluate fetal arrhythmias. An association between atrial arrhythmias and an atrial septal aneurysm has been noted in children and adults. In this study, 105 fetuses were evaluated by fetal echocardiography, 39 (37%) referred to evaluate fetal arrhythmia and 66 (63%) to rule out congenital heart disease. An atrial septal aneurysm was found in 42 (40%) of the fetuses and an atrial arrhythmia in 37 (35%). An atrial septal aneurysm was found in 25 (64%) of the 39 fetuses referred to evaluate a fetal arrhythmia compared with only 17 (26%) of the 66 fetuses referred to rule out congenital heart disease. In this study, the association of an atrial septal aneurysm with an atrial arrhythmia was highly significant (p less than 0.001).
Arrhythmias, Cardiac↗
Duration of ductal shunting in healthy preterm infants: an echocardiographic color flow Doppler study.
The purpose of this investigation was to assess the duration of ductal shunting after birth in healthy preterm infants (30 to 37 weeks gestational age) without evidence of respiratory distress. Thirty-six infants were evaluated in the first 12 hours of life by means of two-dimensional echocardiography and color flow Doppler techniques, and then once daily until no ductal flow was detected (defined as functional closure). Preterm infants were subdivided into two groups by gestational age: group 1 = 30 to 33 weeks (n = 12); group 2 = 34 to 37 weeks (n = 24). Sixteen full-term infants (38 to 41 weeks) were similarly evaluated as control subjects (Group 3). One infant from each group had a closed ductus at the time of the first study (performed at a mean of 7.7 +/- 3.2 hours). Subsequent studies for the entire group were performed at a mean of 31.3 +/- 5.4 hours (day 2), 55.0 +/- 4.5 hours (day 3), and 80.3 +/- 6.1 hours (day 4). For the three groups, the rates of ductal closure ranged from 50.0% to 58.3% on day 2 and 81.3% to 87.5% on day 3. For the entire group, all but one infant had demonstrated closure of the ductus arteriosus by day 4. Within the range of gestational ages studied, we conclude that prematurity, in the absence of respiratory distress syndrome, does not prolong the initial duration of physiologic ductal shunting.
Ductus Arteriosus↗
Hypertrophic cardiomyopathy in infants of diabetic mothers: an update.
Infants of diabetic mothers (IDMs) are at known risk for developing a hypertrophic type of cardiomyopathy. The severity of IDM cardiomyopathy can vary from an incidental finding on echocardiography to an infant with severe symptoms of congestive heart failure. The purpose of this article is to review the pathophysiologic mechanisms involved in the development of cardiomyopathy in IDMs and to discuss the diagnostic tests utilized in making the diagnosis (especially echocardiography) and the potential mechanisms that may result in congestive heart failure. This report will conclude with a review of a 2 1/2 year prospective study of diabetic women who had carefully maintained diabetic control during pregnancy. Although the IDMs in this study continued to have mild evidence of generalized hypertrophy when compared with control newborn infants, none developed symptoms of congestive heart failure. These data support the contention that careful diabetic management in pregnancy reduces the severity of hypertrophic cardiomyopathy in IDMs.
Cardiomegaly↗