Biomedical subjects

G Lingman

Publications and source records attributed to G Lingman.

47 records · Page 3Linked to original sources

PubMed1987

Fetal blood flow in pregnancies complicated by intrauterine growth retardation.

A noninvasive pulsed Doppler ultrasound technique was used to characterize blood flow in the descending thoracic aorta and the intra-abdominal part of the umbilical vein in 159 fetuses suspected of intrauterine growth retardation (IUGR) on the basis of ultrasound fetometry. From this group, 74 infants with IUGR (defined as gestational age-related birth weight of 2 standard deviations [SD] or more below the population mean) were born. The blood flow results were not available to the clinicians managing the pregnancies. Blood flow mean velocity in the fetal aorta was lower, pulsatility index and rising slope higher, and umbilical volume flow and umbilical flow per 100 g placental tissue were lower in the pregnancies with IUGR than in 21 normal pregnancies. The waveform of the maximum aortic velocity envelope was related to operative delivery for fetal distress, Apgar score, and umbilical cord blood pH. The pulsatility index and the configurational assessment of the diastolic part of the waveform were combined to form a new concept, the blood flow class. The blood flow class was abnormal in 57% of the fetuses classified as having IUGR at birth and in 93% of those growth-retarded fetuses who subsequently developed signs of fetal distress requiring operative delivery. Waveform analysis, in terms of blood flow class, seems to be a useful tool in the surveillance of fetuses when IUGR is suspected. Abnormal blood flow class is a marker of fetal distress and probably gives an earlier indication than antenatal nonstressed cardiotocography. The results of this study point to a strong association between IUGR and impaired fetal blood flow. The aortic volume blood flow, unlike waveform analysis, does not seem to be a variable sensitive enough to predict fetal outcome in the individual pregnancy.

Aorta, Thoracic↗

PubMed1986

Circulatory effects of fetal cardiac arrhythmias.

The circulatory consequences of cardiac arrhythmia and its compensatory mechanisms were examined in utero in 37 fetuses. A combined real-time and 2-MHz pulsed Doppler technique was used to measure blood velocity for waveform analysis and flow estimation in the descending thoracic aorta of the fetuses. The pattern of blood velocity in the inferior vena cava was studied to classify the arrhythmia. Despite severe cardiac arrhythmias the aortic blood flow was within normal limits in all but one fetus which had associated cardiac malformation and congestive failure. The rising slope and the peak value of the maximum aortic velocity were significantly increased in the postpremature beats and in fetuses with atrioventricular block. The results support the validity of Frank-Starling's law for the fetal myocardium.

Adult↗

PubMed1986

Fetal central blood circulation in the third trimester of normal pregnancy--a longitudinal study. I. Aortic and umbilical blood flow.

Fetal central blood circulation was evaluated in 21 uncomplicated pregnancies every other week from the 27th gestational week till term. Blood flow in the fetal descending thoracic and abdominal aorta and in the intra-abdominal umbilical vein was measured with a combined ultrasound real-time and 2 MHz pulsed Doppler technique. The mean fetal blood velocities were fairly constant at the three measuring sites during the last trimester: 34.6 cm X s-1 (S.D. 5.5), 32.7 cm X s-1 (S.D. 5.5) and 12.6 cm X s-1 (S.D. 3.1), respectively. The aortic diameter increased with gestational age, whereas the umbilical vein diameter increased until the 34th gestational week followed by a stagnation. The mean weight-related blood flow in the fetal thoracic descending aorta decreased slightly towards term (from 240.8 ml X min-1 X kg-1 (S.D. 53.6) in the 28th week to 212.6 ml X min-1 X kg-1 (S.D. 37.3). In the umbilical vein, the corresponding blood flow decrease was linear and more pronounced: from 138.7 ml X min-1 X kg-1 (S.D. 76.0) to 65.2 ml X min-1 X kg-1 (S.D. 14.2). The results indicate that the placental proportion of fetal blood flow decreases with gestational age.

Adult↗

PubMed1986

Fetal central blood circulation in the third trimester of normal pregnancy--a longitudinal study. II. Aortic blood velocity waveform.

Waveform of the maximum blood velocity recorded from the fetal descending thoracic and abdominal aorta was analyzed in a longitudinal study on 21 normal pregnancies from the 27th gestational week till term. Measurements of blood velocity were performed with combined real-time linear array and 2 MHz pulsed Doppler ultrasound technique every second week. The rising (RS) and the descending (DS) slopes did not change with gestational age in the thoracic descending aorta. The peak maximum velocity, the pulsatility index (PI) and the acceleration time percentage were constant during the last trimester of pregnancy, in both the thoracic and the abdominal aorta. In the former, the mean RS was 29.9 (S.D. 4.9), mean DS 5.3 (S.D. 0.9), mean peak velocity 115.6 cm X s-1 (S.D. 19.0), mean PI 1.96 (S.P. 0.31) and the mean acceleration time percentage 19.2% (S.D. 2.2). In the abdominal aorta, the mean RS was 25.7 (S.D. 5.6), mean DS 4.5 (S.D. 0.9), mean peak velocity 99.7 cm X s-1 (S.D. 18.8), mean PI 1.68 (S.D. 0.28) and the mean acceleration time percentage 19.1% (S.D. 2.2). The PI and the DS, considered to reflect mainly peripheral vascular resistance, were mutually related (r = 0.72). The acceleration time percentage, RS and PI did not show any relation to fetal heart rate or gestational age which justifies the use of gestational age-independent reference values for those parameters during the last 3 months of gestation, at least within the normal fetal heart rate range.

Aorta↗

PubMed1986

Clinical outcome and circulatory effects of fetal cardiac arrhythmia.

By means of abdominal fetal ECG and non-invasive ultrasound blood flow studies 113 cases of fetal cardiac arrhythmia were classified according to the origin of arrhythmia. Pregnancy outcome was characterized by an increased frequency of fetal distress and heart malformation, and increased fetal and neonatal mortality. The following types of arrhythmia were identified: supraventricular extrasystoles (n = 84), paroxysmal tachycardia (n = 6), sinus bradycardia (n = 3), atrial flutter (n = 1), ventricular extrasystoles (n = 14), and atrioventricular block (n = 5). In 37 cases the combined Doppler and real-time ultrasound technique was used to measure fetal aortic blood flow as a means of studying the circulatory effects of the arrhythmia. Increased peak velocity, rising slope and acceleration were found in the first post-pausal beat after a supraventricular extrasystole or a missed beat; this supports the validity of Frank-Starling law for the fetal heart and suggests that a strong relationship exists between these variables and myocardial contractility. In two cases of intra-uterine heart failure, the effect of digoxin treatment in utero on the fetal aortic flow variables was studied, results indicating a positive inotropic effect of the drug on the fetal myocardium. The estimation of fetal aortic volume blood flow in cases of fetal cardiac arrhythmia is useful for early detection of fetal cardiac failure, and for monitoring the effects of intra-uterine treatment.

Adult↗

PubMed1986

Circulatory changes in fetuses with imminent asphyxia.

Blood flow was measured in 11 term fetuses who were later delivered by means of emergency caesarean section because of cardiotocographic changes indicating imminent asphyxia. Blood flow was recorded in the fetal descending aorta and in the intraabdominal part of the umbilical vein by combined real-time and 2-MHz pulsed Doppler ultrasound method. In all 11 fetuses, the waveform of the maximum aortic blood velocity was changed in a typical way with elimination of the diastolic flow (zero flow). In 4 of the fetuses, a short-lasting reversal of the diastolic flow occurred. In 5 fetuses, the pulsatility index of the aortic flow was increased, and the aortic volume flow was pathologically low in 3 fetuses. In the umbilical vein, the volume flow was within normal limits in all cases. The umbilical flow, which normally is continuous and nonpulsatile, showed heart-synchronous pulsations in 3 of the fetuses. The typical changes in the aortic diastolic flow occurred 1-3 days before the onset of the cardiotocographic changes. This suggests that the changes in the fetal aortic blood velocity might be a clinically useful early sign of imminent asphyxia.

Amniotic Fluid↗

PubMed1986

Fetal cardiac arrhythmia. Clinical outcome in 113 cases.

In 113 cases of fetal cardiac arrhythmia, i.e. 94 with supraventricular arrhythmia, 5 with atrioventricular block and 14 with ventricular arrhythmia, the clinical outcome was studied and compared with the general pregnant population. The arrhythmia group was afflicted with a significantly increased frequency of congenital malformations, 6.2% vs. 2.0%; fetal distress in labor, 20.4% vs. 13.5%; perinatal mortality, 3.5% vs. 0.7%; and neonatal mortality, 1.8% vs. 0.1%. In 4 cases, pharmacological cardiac treatment was needed in utero due to fetal heart failure. Fetuses with cardiac arrhythmia thus constitute an obstetric and pediatric high-risk group that should be subjected to an intensified supervision to detect fetal heart failure or fetal distress. When indicated, these complications can be treated in utero.

Adolescent↗

PubMed1986

Fetal volume blood flow and umbilical artery flow velocity waveform analysis: a comparison.

The estimation of fetal umbilical vein and aortic volume blood flow was compared with umbilical artery flow velocity-time waveform analysis in 42 pregnancies. The volume blood flow measurements were made with a combined linear array B-mode and pulsed Doppler ultrasound system. The umbilical artery flow velocity-time waveform analysis was made with either pulsed or continuous wave 2 MHz Doppler ultrasound and the systolic/diastolic (A/B) ratio was used as an index of flow resistance. There was no difference when continuous wave was compared to pulsed Doppler ultrasound as a method of recording flow velocity waveforms. Analysis of the umbilical artery flow velocity-time waveform was more sensitive (100%-50%) than the measurement of umbilical vein volume blood flow (ml/kg/min) in the detection of the small-for-gestational age (SGA) fetus. The predictive value of a positive test was higher (71%-45%) while specificity was similar (88%-81%). Descending aortic volume flow was reduced in only one SGA fetus. The increase in umbilical placental downstream resistance (high systolic/diastolic ratio) was associated with a reduction in the percentage of fetal aortic blood flow directed to the umbilical placental circulation.

Adult↗

PubMed1984

Haemodynamic assessment of fetal heart arrhythmias.

The effects of fetal heart arrhythmias were examined serially in two pregnancies by three non-invasive methods: fetal ECG, fetal phonocardiography and ultrasonic measurement of fetal blood flow. In a case of supraventricular arrhythmia, there was evidence suggesting that the stroke volume varied with ventricular filling according to the Frank-Starling law. In a case of total atrioventricular block the mean blood flow in the fetal descending aorta and in the umbilical vein was within the normal range. Blood flow velocity in the inferior vena cava of the fetus reflected atrial contractions. In the phonocardiogram, a phenomenon similar to 'bruit de canon' was found. Both pregnancies had good outcomes and subsequent development of the infants was normal except for the persisting dysrhythmias. The two cases exemplify how fetal heart function can be assessed in utero.

Adult↗

PubMed1980

Intrauterine digoxin treatment of fetal paroxysmal tachycardia. Case report.

A patient with fetal paroxysmal supraventricular tachycardia (PST) with a heart rate above 300 beats/minute in the 29th week of pregnancy is described. The fetus showed signs of severe cardiac failure and was, therefore, digitalized by giving the mother 0.5 mg digoxin intravenously on the first day and the 0.25 mg oral digoxin daily throughout the pregnancy. After one day a normal rhythm was observed. The patient was delivered of a healthy girl after 38 weeks of pregnancy. Digoxin concentrations in samples of umbilical cord vein and artery, intrapartum scalp capillary, and amniotic fluid were almost equal, but somewhat lower than in simultaneously obtained maternal serum. Intrauterine digoxin treatment of fetuses with PST is discussed.

Adult↗

PubMedDate not supplied

Blood flow in the fetal descending aorta; intrinsic factors affecting fetal blood flow, i.e. fetal breathing movements and cardiac arrhythmia.

An ultrasonic method combining real-time ultrasonography and pulsed Doppler technique was used for the examination of blood flow in the fetal descending aorta. The mean aortic blood flow velocity in the last trimester of normal pregnancies was 29.0 cm/s; the peak maximum velocity 97.3 cm/s and the mean blood flow 238.4 ml/min/kg. The blood flow velocity did not change significantly with gestational age, the aorta diameter showed a linear growth. During labour, the aortic blood flow in undistressed fetuses was not different from the flow recorded during late pregnancy. Fetal breathing movements modulate the flow velocity signals in the descending aorta, the inferior vena cava and the umbilical vein of the fetus; therefore, when quantifying fetal blood flow, only periods without fetal breathing movements should be considered. A group of fetuses with various types of cardiac arrhythmias was examined. Postextrasystolic potentiation was found to be present already during intrauterine life. The present method enables quantitative evaluation of the hemodynamic effects of cardiac arrhythmias.

Aorta, Thoracic↗