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Biomedical subjects

M D Reller

Publications and source records attributed to M D Reller.

51 records · Page 3Linked to original sources
PubMed1987

Tricuspid regurgitation in newborn infants with respiratory distress: echo-Doppler study.

The purpose of this investigation was to use Doppler echocardiography to evaluate respiratory problems significant enough to warrant supplemental oxygenation in newborn infants. Of 17 infants (mean gestational age 37.5 weeks, mean birth weight 3070 g) 14 (82%) had detectable tricuspid regurgitation. By modified Bernoulli equation, all infants had right ventricular pressure greater than 60% of systemic pressure, and nine of 14 had estimated right ventricular pressure at or near systemic pressures. In eight infants for whom sequential evaluations could be obtained, right ventricular pressure as a percentage of systemic pressure gradually decreased, and corresponded to decreasing needs for supplemental oxygenation. Tricuspid regurgitation could no longer be detected between 3 and 16 days after the first study, and was associated with decreased right ventricular pressures (less than 50% systemic) and weaning from supplemental oxygenation. We conclude that in the near-term infant with early respiratory difficulties, tricuspid regurgitation is common and is associated with increased right ventricular pressure.

Blood Pressure↗
PubMed1987

Fetal lamb ventricles respond differently to filling and arterial pressures and to in utero ventilation.

Right and left ventricular function were investigated in 12 fetal lambs (127-140 days gestation) instrumented with electromagnetic flow sensors on the ascending aorta and the main pulmonary artery, and with vascular catheters. Nine fetuses were equipped with a postductal aortic occluder and the trachea was cannulated in eight. Control arterial blood values were pH 7.36 +/- 0.02 (SD), PCO2 49.3 +/- 2.3 torr, PO2 18.4 +/- 1.7 torr, and hematocrit 37.3 +/- 4.4%. Biventricular function curves relating stroke volume to mean right and left atrial pressure were generated by rapid withdrawal and reinfusion of fetal blood. Both function curves were composed of steep ascending and plateau limbs that intersected at a breakpoint. Stroke volumes at the breakpoints were 0.94 +/- 0.19 ml.kg-1 and 0.63 +/- 0.15 ml.kg-1 for right and left ventricle, respectively (p less than 0.001). During postductal aortic occlusion, arterial pressure increased by 19.3 +/- 7.9 torr while right ventricular stroke volume decreased by approximately 48% and left ventricular stroke volume decreased by approximately 9%. In utero ventilation increased arterial pressure, heart rate, PO2, and oxygen content. Right atrial pressure increased from 3.9 +/- 1.3 to 5.8 +/- 2.9 torr (p less than 0.05); left atrial pressure from 3.5 +/- 1.5 to 10.0 +/- 4.4 torr (p less than 0.05). Aortic flow nearly doubled (112 +/- 29 to 211 +/- 35 ml.min-1.kg-1) (p less than 0.05), and the left ventricular function curve shifted upward. The right ventricular function curve was shifted downward during ventilation. We conclude that the fetal ventricles differ significantly in their outputs, response to changes in arterial pressure, and to the onset of in utero ventilation.

Animals↗
PubMed1986

Left ventricular function in normal newborn infants and asymptomatic infants with neonatal polycythemia.

Digitized M-mode echocardiography was used to evaluate left ventricular (LV) function in normal neonates and to document subtle abnormalities of LV function in 19 asymptomatic newborn infants with polycythemia and hyperviscosity. Echocardiograms were performed before and after partial exchange transfusion and at 48 hours of age. Results were compared to those obtained from analysis of echocardiograms from 18 normal infants with normal hematocrits at 12 and 48 hours of age. In the normal group there were no differences between the digitized indices of LV function at 12 hours and those at 48 hours of age. In the polycythemic group, prior to hemodilution, the peak rate of LV emptying was low compared to normal values (-3.1 +/- 0.7 sec-1 vs -3.6 +/- 1.0 sec-1, p less than 0.05) and normalized following the procedure to -3.7 +/- 1.3 sec-1. The peak rate of left ventricular posterior wall (LVPW) thickening also increased following partial exchange transfusion (3.2 +/- 0.6 sec-1 to 3.7 +/- 1.0 sec-1, p less than 0.05). At 48 hours of age peak rates of change for the left ventricle (-2.9 +/- 0.8) and LVPW (3.0 +/- 0.7) were abnormally low in the polycythemic infants, all of whom had undergone partial exchange transfusion. Also, at 48 hours, the LVPW time to peak rate of thickening and time to the end of thickening were prolonged. In addition, the peak rate of LV filling in diastole was low in the polycythemic group (3.0 +/- 0.9 sec-1 vs 3.9 +/- 1.3 sec-1, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Viscosity↗
PubMed1986

Right ventricular function in the hypoxaemic fetal sheep.

Right ventricular function was investigated in seven fetal sheep (125-130 days gestation) hypoxaemic at a mean of 5 days postoperation, and were compared to nine normoxaemic fetal sheep of the same gestation. Arterial O2 and CO2 tensions, pH, and haematocrit values for the hypoxaemic and normoxaemic fetuses were 15.6 +/- 1.0 vs. 20.6 +/- 1.8 torr, 49.4 +/- 4.1 vs. 46.1 +/- 1.6 torr, 7.38 +/- 0.02 vs. 7.39 +/- 0.02, and 29 +/- 7.5 vs. 31 +/- 5.3%, respectively. Right ventricular output and stroke volume were similar in the two groups, 241 +/- 57 vs. 247 +/- 75 ml X min-1 X kg-1 and 1.5 +/- 0.4 vs. 1.5 +/- 0.4 ml X kg-1, respectively. Filling and afterload pressures were also similar in the hypoxaemic and normoxaemic fetuses with right atrial pressure of 3.0 +/- 1.0 vs. 3.7 +/- 1.2 mmHg, and arterial pressure of 42 +/- 5 vs. 43 +/- 4 mmHg, respectively. Ventricular function curves were produced by rapid withdrawal and re-infusion of fetal blood producing curves with a steep ascending limb and a plateau phase. The breakpoint joining the limbs of the control function curve for the hypoxaemic and normoxaemic fetuses were right atrial pressure 2.9 +/- 1.0 vs. 3.4 +/- 1.2 mmHg and a stroke volume of 1.5 +/- 0.5 vs. 1.5 +/- 0.4 ml X kg-1, respectively. Linear regression of stroke volume against arterial pressure from 30-90 mmHg during infusions of nitroprusside and phenylephrine at right atrial filling pressures greater than breakpoint was stroke volume = 0.018 ml X kg-1 X mmHg-1 arterial pressure +/- 2.25 ml X kg-1. This equation is not different from that calculated in normoxaemic fetuses, and demonstrates that the fetal right ventricle is quite sensitive to changes in arterial pressure. These data indicate that reduction in fetal oxygen content by an estimated 40% does not affect fetal right ventricular function.

Animals↗
PubMed1985

Hemodynamically significant PDA: an echocardiographic and clinical assessment of incidence, natural history, and outcome in very low birth weight infants maintained in negative fluid balance.

Fifty very low birth weight (VLBW) infants (750-1500 g, 27-33 weeks gestational age) were assigned at random to one of two groups of negative fluid balance and underwent prospective clinical and echocardiographic examinations during the first month of life. The purpose was to determine: the effect of fluid restriction on the incidence of ductal shunting, the reliability of the physical examination in diagnosing significant ductal shunting, and the relationship between significant ductal shunting and outcome in such infants. None of the infants had manipulations to close the ductus during the first week of life. Using routine structural and functional echocardiographic indices as criteria for the diagnosis of hemodynamically significant ductal shunting (hsPDA), we found that the two fluid-balance groups (8%-10% weight loss vs 13%-15% weight loss) did not significantly differ in incidence of hsPDA, duration of ventilation, or development of BPD. These two groups were then combined for further analysis: 32 (64%) of 50 VLBW infants had hsPDA during the first week of life. The group of infants with hsPDA did not differ significantly from that without hsPDA in birth weight or gestational age, but had a significantly lower Apgar score (P less than 0.04) and was significantly more likely to require ventilator support for RDS (P less than 0.01). Although when present a typical ductal murmur was specific for the development of significant ductal shunting, no murmur was heard in 21 (66%) of 32 infants with early hsPDA.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Weight↗
PubMed1985

Relationship of prospective diabetes control in pregnancy to neonatal cardiorespiratory function.

We evaluated two groups of diabetic women in pregnancy who differed primarily in the time of initiation of careful diabetes management. Group A (early) were entered in the first trimester (n = 35); group B (late) were entered in the late second or early third trimester (n = 28). Normal women delivering at the same period were used as controls (n = 23). All infants were evaluated by a thorough clinical and echocardiographic examination between 24 and 72 hours of life. Both groups of infants of diabetic mothers had mild increase in mean thickness of ventricular and septal walls compared with those of normal newborn infants, and both had a significant percentage with septal hypertrophy (43% vs 39%). None of the infants in the early group had respiratory symptoms requiring oxygen therapy, compared with 19% in the late group. The early group had significantly fewer infants with elevated right ventricular systolic time interval ratios than did the late group (20% vs 50%); none of the normal infants had elevated ratios. We conclude that careful management of diabetes in pregnancy reduces the severity of hypertrophic cardiomyopathy, although no advantage of early vs late management was obvious. Early management does significantly reduce the number of infants of diabetic mothers who develop respiratory symptoms requiring oxygen therapy.

Cardiomyopathy, Hypertrophic↗
PubMed1985

Influence of airway pressure waveform on cardiac output during positive pressure ventilation of healthy newborn dogs.

During positive pressure ventilation, increases in mean airway pressure produced by increases in end expiratory pressure are associated with reductions in cardiac output. Mean airway pressure may be increased not only by increasing end expiratory pressure, but also by increasing the inspiratory pressure or the inspiratory to expiratory time ratio. During positive pressure ventilation of 10 healthy newborn dogs, cardiac output and left ventricular dimensions were measured using radioactive microspheres and echocardiography, respectively. Baseline ventilation was produced using the least inspiratory pressure to maintain normocarbia (rate = 50 min-1, inspiratory to expiratory time ratio = 1:3, end expiratory pressure = 2 cm H2O). The mean airway pressure was increased 3-fold by independently changing the airway pressure waveform through increases in inspiratory pressure, inspiratory to expiratory time ratio, or end expiratory pressure. Despite differences in airway pressure waveform, similar reductions in left ventricular dimension, cardiac output, and stroke volume were seen. We conclude that at a given increased mean airway pressure during positive pressure ventilation, the reduction in cardiac output is independent of the airway pressure waveform.

Animals↗
PubMed1985

Effects of neonatal polycythemia and partial exchange transfusion on cardiac function: an echocardiographic study.

Although infants with neonatal polycythemia and hyperviscosity often present with cardiorespiratory distress, little information is available regarding the cardiac function of such babies before or after partial exchange transfusion. To assess cardiac function, we performed M-mode echocardiograms in 19 asymptomatic newborn infants (4 to 12 hours of age) who had venous hematocrits greater than 65%. The echocardiograms were performed immediately prior to and following partial exchange transfusion and were repeated at 48 hours of age. Eighteen matched newborn controls also underwent echocardiography within the first 12 hours of life and again at 48 hours. Polycythemic newborns had elevated right ventricular preejection period to right ventricular ejection time ratios compared with controls (0.46 +/- 0.11 v 0.37 +/- 0.04, P = .002), suggestive of increased pulmonary vascular resistance. These indexes normalized following partial exchange transfusion. In addition, the polycythemic newborns were relatively bradycardic prior to exchange (116 +/- 13 beats per minute v 125 +/- 16 beats per minute, P less than .05), but heart rates normalized following the procedure. At 48 hours, the polycythemic and control groups were different only in that the mean shortening fraction of the polycythemic group was lower than that of the controls (32% +/- 4% v 36% +/- 6%, P = .02). The findings are consistent with elevated pulmonary vascular resistance associated with polycythemia and hyperviscosity. Cardiac output may be lower in polycythemic infants. The finding of reduced fractional shortening in polycythemic infants at 48 hours following partial exchange transfusion is unexplained.

Blood Viscosity↗
PubMed1984

Recurrence of patency of the ductus arteriosus after surgical ligation in premature infants.

Two premature infants who had surgical ligation of their patent ductus arteriosus are described. These infants initially did well postoperatively but then developed congestive heart failure. Both infants had echocardiographic evidence of recurrence of their patent ductus arteriosus. One of the infants required a repeat ligation procedure. It is important to continue to monitor premature infants for the return of clinical signs of a patent ductus arteriosus after surgical ligation.

Ductus Arteriosus, Patent↗
PubMed1983

Normal aortic root dimensions in premature infants.

Normal aortic root dimensions are established using 334 sequential echocardiograms in 111 average-gestational-age premature infants between 600-2500 g. The aortic roots increased in diameter from 0.53 cm +/- 0.04 cm for infants weighing 600-900 g to 0.80 +/- 0.08 cm for infants weighing between 2200-2500 g.

Aorta↗
PubMed1982

Water balance in very low-birth-weight infants: relationship to water and sodium intake and effect on outcome.

The clinical effects of fluid therapy designed to maintain different degrees of negative water balance during the first five days of life were determined prospectively in 88 very low-birth-weight infants. Infants with birth weights of 750 to 1,500 gm were matched for birth weight in 250 gm increments. RDS or no RDS, asphyxiated or not, and inborn or outborn. Each infant was randomized to either Group 1--fluids managed to allow 1 to 2% loss of BW per day to a maximum loss of 8 to 10%, or Group 2--fluids managed to allow 3 to 5% loss of BW per day to a maximum loss of 13 to 15%. The mean five-day cumulative fluid input in Group 2 was 220 ml/kg less than in Group 1, yet Group 2 lost only 41 gm/kg more than did Group 1 (8.8% of BW lost in Group 1 vs 12.9% of BW lost in Group 2, P less than 0.001). There were no statistically significant differences between the groups in incidence of clinically significant patent ductus arteriosus, intracranial hemorrhage, bronchopulmonary dysplasia, necrotizing enterocolitis, dehydration, acute renal failure, or metabolic disturbances. There was no difference in duration of respiratory support required, in time to regain BW, or in time to discharge. There was no difference in the neonatal mortality rate. Fluid input in VLBW infants can be flexible to allow the gradual loss of 5 to 15% of birth weight during the first week of life without adversely affecting outcome.

Body Weight↗
PubMedDate not supplied

Views of physicians in training on the ethical and legal issues in preliminary reporting of echocardiographic data.

Cardiac sonographers may be pressured by physicians into giving diagnostic interpretations of echocardiographic data. This study investigated the issue of preliminary reporting of echocardiographic data. A questionnaire was sent to 292 physicians; 85 physicians (29%) responded. Seventy-two physicians (87%) thought they had more than a minimal knowledge of echocardiography, 94% wanted a written or verbal preliminary report, and 84% thought that giving a preliminary report should be part of the cardiac sonographer's job. If abnormalities were found, 80% wanted the results before a cardiologist reviewed the study, and 56% would want a diagnostic rather than a descriptive report. Fifty-four physicians (64%) would pressure the cardiac sonographer into giving a preliminary echocardiographic report and would use this information to manage the patient. The majority of the physicians thought that it is legal for the cardiac sonographer to give a preliminary echocardiogram report. Eighty percent said that the cardiac sonographer would not be "practicing medicine without a license," and 82% that the sonographer would not be "aiding and abetting the unauthorized practice of medicine." This data would indicate that physicians at Oregon Health Sciences University want the cardiac sonographer to give preliminary echocardiographic results, even though the sonographer may be breaking state statutes.

Adult↗
PubMedDate not supplied

Academic physicians' opinions on preliminary reporting of echocardiographic data.

Preliminary reporting of echocardiographic data by cardiac sonographers has become a key issue in the echocardiography community. A survey on this issue was sent to 248 academic physicians and 89 (35.8%) were returned. In response to a question in the survey, 76 physicians stated that they had at least a limited amount of knowledge in echocardiography. For the group, 62% wanted a written or verbal preliminary report and 52% concluded that this report should be a part of the cardiac sonographer's position. If cardiac abnormalities are suspected, 65% wanted the results before the cardiologist reviewed the study, but only 42% of the physicians wanted a diagnostic versus a descriptive type of report. About 49% stated that if necessary they would attempt to influence the cardiac sonographer to give them a preliminary report, whereas 67% of the physicians would possibly use this information to medically manage the patient. Fifty percent believed that it was legal for a cardiac sonographer to give a preliminary report. Another 70% said that the cardiac sonographer would NOT be "practicing medicine without a license" and 66% concluded that they would NOT be "aiding and abetting the unauthorized practice of medicine" if given this information. These data have important potential ramifications for both cardiac sonographers as well as for the practice of cardiology regarding the issue of preliminary echocardiographic reports.

Adult↗
PubMedDate not supplied

Echocardiographic imaging techniques with subcostal and right parasternal longitudinal views in detecting sinus venosus atrial septal defects.

Sinus venosus atrial septal defects are frequently missed and difficult to visualize with conventional two-dimensional echocardiographic views. Using modified subcostal and right parasternal longitudinal views, nine patients were found to have a sinus venosus atrial septal defect. The modified subcostal view showed a sinus venosus atrial septal defect in all nine patients; three patients had secundum atrial septal defects as well. The right parasternal view detected only six patients with sinus venosus atrial septal defect. Partial anomalous pulmonary venous return was diagnosed in seven patients using these views. The combination of subcostal and right parasternal longitudinal imaging views will improve the detection of sinus venosus atrial septal defects.

Adolescent↗