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Biomedical subjects

A Kurjak

Publications and source records attributed to A Kurjak.

At least 145 records · Page 8Linked to original sources
PubMed1987

Color flow mapping in obstetrics.

Blood flow studies are now used extensively in evaluating fetal peripheral circulation. By using continuous and pulsed Doppler ultrasonic equipment the raw Doppler shifts caused by blood moving in the vessels can be analyzed in different ways. Spectral data can be used to estimate blood velocity and volume in the vessel, and pulsatility characteristics and turbulence. All these data are obtained from very restricted areas within the body so that aiming of the probe is critical, and obtaining data from an area requires long and tedious effort. Color flow mapping which has recently been introduced into clinical practice provides an overview of flow velocities and directions within an area. Color coded flow can be displayed by applying the moving target identification principle (as in radar) to an ultrasonic diagnostic instrument where sound waves are used instead of radio waves. The value of flow mapping has already been recognized in the diagnosis of congenital and acquired heart disease in adults and children. Direct visualization of intracardiac flow provides for a fast and accurate diagnosis of various cardiac defects, such as the ventricular septal defect, without cardiac catheterization. In the present study we have investigated the potential of color flow mapping in obstetrics. 211 pregnant women were examined between the 15th and 40th weeks of pregnancy. 193 of them had normal pregnancies; 18 were abnormal, including 11 cases of insulin dependent diabetes, 2 cases of Rh-immunization, 2 cases of nonimmunologic fetal hydrops, 2 cases of fetal cardiac structural defects and 1 case of intrauterine growth retardation. Intracardiac flow was clearly seen in 78% (35/45) of cases at the gestational age between the 20th and 24th weeks. After the 24th week the heart flow visualization rate gradually decreased to 31% (11/36) before term. In 2 cases of congenital heart abnormality flow mapping enabled clear visualization of reverse flow through the tricuspid valve and diagnosis of valvular insufficiency. The best results in studies of flow in peripheral vessels were obtained from umbilical vessels which were seen in all cases after the 15th week. The flow visualization rate was much lower when the fetal aorta, intrahepatic umbilical vein and internal carotid artery were studied. The comparison between the diameter of the umbilical vein measured on the B-scan and flow width in the same vessel showed no significant difference (t = 0.26; p less than 0.01; N = 209).(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Flow Velocity↗
PubMed1987

Ultrasonically guided fetal tissue biopsy.

From January 1984 to October 1986, a total of 185 prenatal diagnostic procedures were performed, viz. 120 chorionic villus samplings, 42 fetal blood samplings, 12 skin biopsies and 11 tumor biopsies. All procedures were performed under continuous ultrasound guidance. The methods are described, and indications for each procedure and clinical outcome discussed. Preliminary results have shown that ultrasonically guided fetal tissue biopsy is feasible for prenatal diagnosis, but randomized trials are needed for evaluation of the risk/benefit ratio.

Biopsy, Needle↗
PubMed1987

[Ultrasound studies of blood flow in the umbilical vein].

The umbilical vein blood flow was examined in a total of 101 healthy pregnant women in 146 occasions between the 28th and 41st weeks of pregnancy. A Kranzbühler 8130 Duplex Doppler machine was used in all of the examinations. It was found that the blood flow is near to the same value (120 ml/min/kg) till the 37 to 38th weeks of pregnancy during the third trimester, then decreases continuously and is about 90 ml/min/kg on the 41st week of pregnancy. The diameter of the umbilical vein increases from 4-5 mm to 6-7 mm, but the rate of growth slows down after the 36-37th weeks. The velocity of the blood flow between the 28th and 41st weeks of pregnancy fluctuates between wide limits (10-24 cm/s), but a slight decrease could be observed from the 36-37 weeks of pregnancy.

Adolescent↗
PubMed1987

Ultrasound examination of blood flow. I. Flow in the fetal aorta.

The descending part of the fetal aorta was examined in a total of 101 healthy pregnant women on 146 occasions between the 28th and 41st weeks of pregnancy. A Kranzbühler 8130 Duplex Doppler apparatus was used throughout. It was found that the blood flow compared to the estimated fetal weight was near to the same value (180-200 ml/min/kg) during the third trimester. The absolute volume of blood flow--not related to fetal body weight--increased about three times from the 28th week to term (200-600 ml/min). The diameter of the fetal aorta increased from 3-4 mm to 7-8 mm during the 3rd trimester. The velocity of blood flow fluctuated between wide limits (20-40 cm/sec), but the average was 28-32 cm/sec. The A/B ratios (A = systolic peak, B = end diastole), the Resistance Indexes (A-B/A), the Pulsatility Indexes (A-B/mean frequency) were nearly the same during the third trimester.

Adult↗
PubMed1986

The use of ultrasound in developing countries.

In many developing countries ultrasound services are either nonexistent or inadequate, although the diagnostic problems for which ultrasound is particularly suited are common in such countries. In view of this, the World Health Organization (WHO) has outlined the indications for diagnostic ultrasound together with the technical specifications for equipment. Where there are larger hospitals the basic ultrasound services should be complemented with the proposed general-purpose ultrasound scanner while at the level of major medical centres there will be need for a variety of special purpose ultrasonic units, e.g. for cardiac, intraluminal and interventional investigations. The usefulness of any ultrasound appliance depends to a great extent on the skill and experience of the operator. Therefore, WHO provides guidance on the training of general practitioner and expert sonographer that is necessary for proper implementations of this technology. In this review the authors discuss the various problems affecting the use of ultrasound in developing countries.

Developing Countries↗
PubMed1986

[Ultrasound study of blood flow velocity in the umbilical artery].

The blood flow velocity waveforms fo the umbilical artery were examined in 101 healthy pregnant women in 146 occasions. A Kranzbühler 8130 Duplex Doppler equipment was used in all of the examinations. Their results were estimated by the A/B ratios (A = systolic peak, B = end diastole) and the Resistance Indexes (Formula: see text). It was found that the A/B ratio decreased from 3.0 to 2.0 and the Resistance Index from 0.6 to 0.5 from the 28th week of pregnancy till term. The changes showed that the resistance of the placental bed decreased continuously in healthy pregnant woman during the third trimester.

Adolescent↗
PubMed1986

[Ultrasound studies of arterial blood flow in the pregnant uterus].

The blood flow velocity waveforms of the arcuata artery were examined in 101 healthy pregnant women in 292 occasions. A Kranzbühler 8130 Duplex Doppler equipment was used in all of the examinations. Their results were estimated by the A/B ratios (A = systolic peak, B = end diastole) and resistance indexes (A-B divided by A). It was found that the examined period both parameters showed an almost constant value which is characteristic to a low resistance place. A significantly stronger blood flow was found at the side of the placental insertion, than at the opposite one.

Adolescent↗
PubMed1985

Ultrasound investigation of the fetal cerebral ventricles.

Significant recent advances in ultrasonic technology have now made possible detailed evaluation of normal and abnormal fetal intracranial anatomy. Accurate knowledge of fetal intracranial anatomy is important for accurate and reproducible cephalometry as well as in antenatal diagnosis of dilated brain ventricles. High resolution real-time ultrasonic investigation was performed in 280 normal obstetric patients from the 14th to the 41st weeks of pregnancy. Eight patients with antenatally detected hydrocephalic fetuses were also included in the study. Measurements of the ratio between lateral ventricular width and cerebral hemispheric width (LVW/HW) showed value at 0.61 of the 14th week to 0.29 at about the 27th week. This value then remains unchanged until term. Accordingly the LVW/HW ratio decreases as the fetus grows reflecting the developmental changes. Due to this simple measurement technique, it is possible to diagnose hydrocephaly much earlier than by means of the identification of an abnormal BPD growth or a discrepancy between head and abdomen circumferences. Although the earliest reported cases of prenatal ultrasound detection of hydrocephaly have been at 17-18 weeks, one must be very careful when making the diagnosis prior to 20 weeks because the lateral ventricles are usually disproportionally large at this time and the LVW/HW ratio is, therefore, high. Moreover, the normal range is rather wide at this age. For this reason it is useful to repeat the ultrasound examination after one week; if the ratio increases, the diagnosis of hydrocephaly can be made without any doubt.

Cerebral Ventricles↗
PubMed1984

Ultrasound diagnosis and perinatal management of fetal genito-urinary abnormalities.

Approximately 50% of fetal abdominal masses originate in the urinary system and those recognizable ultrasonically include renal dysplasia, renal agenesis and obstruction of the lower excretory channels. Fetal renal anomalies may be discovered co-incidentally during the course of sonographic evaluation of uterine size-dates discrepancy, because they are commonly associated with fetal growth retardation and/or oligohydramnios, or during a planned sonographic follow-up of pregnancies in patients who are at risk of recurrence of such anomalies. The sonographic demonstration of renal anomalies under these circumstances may allow for elective termination of pregnancy, may modify the obstetric management and/or facilitate pediatric and surgical care of the newborn. In the collaboration study at three ultrasonic centers there were 81 cases of genito-urinary tract anomalies detected antenatally in a five years period. Among the detected anomalies there were 30 hydronephrotic fetuses, 12 with multicystic disease, 15 with Potter's syndrome, 10 with polycystic kidney, 9 with Prune Belly syndrome, 4 with isolated renal cysts and 1 with an ovarian cyst. Perinatal management of the fetus with urinary tract abnormalities greatly depends on the accuracy of the diagnosis. It would be justifiable to suggest that an inexperienced observer should not make the final diagnosis. He could be of great help, if one kept a high index of suspicion in patients with a significant family history of oligohydramnios and of unexplained abnormal cystic structures in the fetal abdomen and seek the help of a special referral center where experience in related cases is concentrated. Once an accurate diagnosis is made, various alternatives are open to the obstetrician. This is primarily dependent upon the type and degree of the abnormality. Unilateral multicystic kidney and hydronephrosis due to obstruction above the level of the urethra appear to be compatible with extrauterine life and should be approached accordingly. If there is massive enlargement of the fetal abdomen, elective cesarean delivery should be considered to prevent the dystocia which may occur with vaginal delivery and to prevent further damage of these vital organs. If bilateral renal agenesis, bilateral multicystic kidneys, or bilateral infantile polycystic kidneys are demonstrated early in gestation, the obstetrician and parents may choose to terminate the pregnancy because these conditions are not compatible with extrauterine life.(ABSTRACT TRUNCATED AT 400 WORDS)

Abnormalities, Multiple↗