Monitoring aspects during port-access cardiac surgery

OBJECTIVE

To report the experience gained at our Cardiosurgical Centre with the recently introduced port-access technique.

METHODS

EXPERIMENTAL DESIGN

Prospective collection of data from the month of October 1997.

SETTING

Regional University HospitaL Patients: Adult patients undergoing coronary bypass graft or mitral valve surgery.

INTERVENTIONS

Port-access technique makes it possible to carry out open-heart procedures through a minithoracotomy and extrathoracic cardiopulmonary bypass with a set of properly designed catheters (Heartport EndoCPB system) for cardioplegia delivery and heart venting.

MEASURES

Transesophageal echography and pressure traces are the main monitoring tools used for the correct placement of these catheters and for the clinical management of the patient.

RESULTS

Sixty-two cases have been performed so far. A complete description of the procedure, with monitoring aspects and problems encountered is thoroughly presented.

CONCLUSIONS

The major differences with traditional cardiac surgery are that interruption of myocardial perfusion is not achieved through a transversal clamp but through an endovascular occlusive balloon and that thoracic access is by minithoracotomy. Unlike traditional open surgery, the surgeon has no direct vision of the position of the clamp and the anesthesiologist can not visually inspect the contractile state of the heart. The operative team has to cope with a multifaceted system of monitored variables that must be continuously integrated and interpreted. Tight cooperation and continuous communication between anaesthesiologist, surgeons and perfusionist appear to be more important than in any other cardiac operation.

Evidence that luteinizing hormone-releasing hormone statin from ovine rete testis fluid is immunologically related to alphaC inhibin

LHRH Statin is a putative gonadal protein that increases the interval between two consecutive LHRH pulses. The present work was aimed at analyzing the immunological homology between LHRH Statin and the N-terminal region of the alphaC subunit of inhibin. Thus, rete testis fluid (RTF) proteins were purified by immunoaffinity chromatography using antibodies against residues 1-7 plus 7-30 (experiment 1, A-fractions) and 14-28 of the alphaC inhibin subunit (experiment 2, B-fractions), and the LHRH Statin activity of the fractions was examined by intracerebroventricular administration in castrated rams followed by RIA of plasma LH levels in 15-min blood samples. Fractions that bound to the immunoaffinity column with low affinity were eluted with 0.5 M NaCl, pH 7.4 (-F2); then highly bound fractions were eluted sequentially in acidic (pH 2.5, -F3) followed by basic conditions (pH 11.5, -F4). In experiment 1, RTF (40 microg, n = 4) and highly bound fractions (A-F3, 30 ng, n = 8, 150 ng, n = 3; A-F4, 120 ng, n = 5) decreased LH mean plasma levels between 4 and 6 h after injection by 39%, 29%, 43%, and 37%, respectively (P<0.001 to 0.01), while the weakly bound fractions (A-F2, 180 ng, n = 4) and albumin control (40 microg, n = 4) had no activity. In experiment 2, RTF (100 microg, n = 4) and B-F3 (100 ng, n = 3) decreased plasma LH levels by 48% and 38%, respectively (P<0.001 to 0.05), whereas B-F4 (100 ng, n = 4) and albumin control (100 microg, n = 4) had no effect. A fraction obtained from B-F3 by gel filtration had significant LHRH Statin activity (63%, n = 6, P<0.001). PAGE with colloidal gold staining revealed 3 high molecular weight bands and 5 low molecular weight bands in B-F3. The 3 high molecular weight bands were shown to belong to the clusterin family and did not appear to have LHRH Statin activity. The 5 low molecular weight bands were all labeled by anti-alphaC inhibin antibodies. Collectively, these results strongly suggest that LHRH Statin has some homology with the 14-28 alphaC inhibin sequence.

Stallion epididymal fluid proteome: qualitative and quantitative characterization; secretion and dynamic changes of major proteins

Proteins present in and secreted into the lumen of various regions of the stallion epididymis were characterized qualitatively and quantitatively by two-dimensional electrophoresis. Using this proteomic approach, 201 proteins were found in the lumen and 117 were found that were secreted by the epithelium in various parts of the organ. Eighteen proteins made up 92.6% of the total epididymal secretory activity, lactoferrin (41.2%) and clusterin (24.8%) being the most abundant. Procathepsin D, HE1/CTP (cholesterol transfer protein), GPX (glutathione peroxidase), beta-N-acetyl-hexosaminidase, and PGDS (prostaglandin D2 synthase) were the other major compounds secreted. The most abundant proteins found in the luminal fluid were albumin and the secreted proteins: lactoferrin, PGDS, GPX, HE1/CTP, and hexosaminidase. Three main secretory epididymal regions were identified from the protein pattern, i.e., regions E0-E2, E3-E5, and E6-E9. Region E0-E2 was characterized by the secretion of clusterin (53%), PGDS (44%), and GPX (6%). Region E3-E5 had the highest number of secreted proteins, the highest protein concentrations (60-80 mg/ml), and the highest spermatocrit value (85%). Lactoferrin (60% in E4), clusterin (29% in E3), hexosaminidase (10% in E3), and procathepsin D (6.9% in E4) were the most abundant proteins in this region. Region E6-E9, in which few region-specific secreted compounds were found, was characterized by a high quantity of lactoferrin in the luminal fluid (2-14 mg/ml). Comparison between the secretion of the major proteins and their concentrations in the lumen throughout the organ showed that the behavior of each protein is specific, in particular for the three isoforms of clusterin.

Synthesis and antisecretory activity of 6-substituted 5-cyanomethylimidazo[2,1-b]thiazoles and 2,6-dimethyl-5-hydroxymethylimidazo[2,1-b][1,3,4]thiadiazole

The synthesis of imidazo[2,1-b]thiazole and imidazo[2,1-b][1,3,4]thiadiazole derivatives, related to known antiulcer agents, is reported. 5-Cyanomethyl-6-methylimidazo[2,1-b]thiazole showed significant antisecretory activity in the isolated rabbit gastric glands assay.

Isolated fetal choroid plexus cysts: role of ultrasonography in establishment of the risk of trisomy 18

OBJECTIVE

The significance of isolated choroid plexus cysts found by ultrasonographic scan during the second trimester as a marker for trisomy 18 is still debated. We analyzed our data and reviewed the series published in the English-language literature to calculate the likelihood ratio of trisomy 18 in the presence of isolated choroid plexus cysts; that is, the factor by which the individual risk of trisomy 18 is increased in the presence of isolated choroid plexus cysts.

STUDY DESIGN

Likelihood ratios were calculated as ratio of the sensitivity to the false-positive rate. Sensitivity was defined as the rate of isolated choroid plexus cysts detected at midgestation among fetuses with trisomy 18. False-positive rate was defined as the rate of choroid plexus cysts detected at midgestation in the population without trisomy 18. The sensitivities of all published series reporting rates of choroid plexus cysts at the time of the first ultrasonographic examination between 14 and 24 weeks' gestation in populations with trisomy 18 and in low-risk populations were included in the analysis. To these we added all cases of trisomy 18 diagnosed at our institution during the period January 1, 1988, through June 30, 1998, in which prenatal ultrasonographic examination was performed between 14 and 24 weeks' gestation.

RESULTS

The prevalence of second-trimester ultrasonographic detection of isolated choroid plexus cysts among fetuses with trisomy 18 was 6.7% (13/194), whereas that in the population without trisomy 18 was 0.9% (752/79,583). The likelihood ratio associated with isolated choroid plexus cysts was therefore 7.09 (95% confidence interval, 3.97-12.18).

CONCLUSION

The presence of isolated second-trimester choroid plexus cysts increases the base risk of trisomy 18 by a factor of 7.09. This likelihood ratio can be multiplied by the risk calculated according to maternal age to obtain the individual risk of trisomy 18 and thus permit more accurate counseling of the patient.

Critical reappraisal of the utility of sonographic fetal femur length in the prediction of trisomy 21

Measurement of femur length (FL) has been advocated as part of a genetic sonogram for the prediction of Down syndrome (DS). However its predictive ability has been inconsistent. We have studied the diagnostic value of this sonographic parameter in a prospective cohort of women with singleton gestations undergoing genetic sonogram between 14 and 22 weeks because of advanced maternal age or family history of aneuploidies. Genetic sonograms were performed at a mean gestational age of 17.0 weeks (range 14-22). DS was diagnosed in 30 fetuses, while 888 were euploid. Mean+/-SD observed/expected (O/E) values of FL (1.00+/-0.10 versus 0.97+/-0.01, p=0.07) were not significantly different between euploid and DS fetuses. Comparison of the regression equations of FL versus biparietal diameter revealed that while the intercepts were not significantly different between euploid and DS fetuses, the difference in slopes reached significance (p=0.04) suggesting that the predictive ability of FL may increase with advancing gestational age. In addition, a MEDLINE search (National Library of Medicine) was conducted for articles published between 1985 and 1998 on fetal femur length in the prediction of trisomy 21. Review of the published literature on the subject suggests that FL is not a consistent or reliable sonographic predictor of DS. Published thresholds of FL should not be used outside of the Institution from which they originated, and each Institution should establish whether this parameter has predictive ability in its own population.

[Risk factors and neonatal outcomes in shoulder dystocia]

BACKGROUND

Shoulder dystocia (SD) is a rare obstetrical complication but linked with a high perinatal morbidity and mortality rate. SD has been associated to a series of maternal and fetal risk factors due to a multifactorial etiology. This study analyzes the incidence of SD, its morbidity and associated risk factors.

METHODS

Cases of SD occurred at the St. Gerardo Hospital (Monza) between January 1992 trough December 1997 have been retrospectively reviewed. Obstetrical and feto-neonatal data regarding cases of SD were compared to data regarding all the cephalic vaginal deliveries occurred in the same period in our Center.

RESULTS

A total of 14,157 cephalic vaginal deliveries were included in this study, of these 21 infants (0.15%) had SD. A significantly higher incidence of SD cases was found in fetal macrosomia, maternal diabetes, induction of labor by PGE2, use of obstetrical vacuum, length of first stage of labor > 4 hours in multiparas and > 8 hours in nulliparas, and length of second stage > 60 minutes, regardless of parity. A closed association was also observed between SD and birth trauma as brachial plexus injury and humerus fracture.

CONCLUSION

The incidence of SD in our population (0.15%) is below the average reported in the literature (0.37-1.1%). The well-known risk factors, whose low positive predictive value can nevertheless modify obstetrical management, are confirmed.

Port access cardiac surgery

The port-access technique for cardiac surgery was recently developed at Stanford University in California as a less invasive method to perform some cardiac operations. The port-access system has been described in detail elsewhere. It is based on femoral arterial and venous access for cardiopulmonary bypass (CPB) and on the adoption of a specially designed triple-lumen catheter described originally by Peters, and subsequently modified and developed in the definitive configuration called the endoaortic clamp.

4-Aminopyridine derivatives with antiamnesic activity

Acetylcholine (Ach) enhancement, useful in the treatment of Alzheimer's disease (AD), may be obtained by means of ion channel modulators such as 4-aminopyridine (4-AP). 4-AP is also the central ring of tacrine, the first drug approved for the treatment of AD. The synthesis and pharmacological activity of three 4-AP derivatives, prepared with the aim of improving their antiamnesic activity, is here described. In two of these compounds 4-AP is connected to 4-aminobutyric acid (GABA), whereas in the third it is connected to 2-indolinone, i.e., the skeleton of linopirdine, another Ach enhancing agent. The new compounds showed potent antiamnesic activity in comparison with piracetam.

Critical appraisal of the use of nuchal fold thickness measurements for the prediction of Down syndrome

OBJECTIVE

Nuchal fold thickness is the best ultrasonographic predictor of fetal trisomy 21. However, the risk assigned on the basis of the commonly used threshold of nuchal fold thickness >/=6 mm does not take into consideration the significant associations between nuchal fold thickness and gestational age and between maternal age and Down syndrome. We propose a new method of calculating Down syndrome probability that takes into account both gestational age at examination and previously assessed probability of Down syndrome.

STUDY DESIGN

Nuchal fold thickness was measured at ultrasonographic examination at 14 to 22 weeks' gestation without previous knowledge of the fetal karyotype. Nuchal cystic hygromas were excluded from analysis. Statistical analyses included correlation, logistic regression to control for other ultrasonographic predictors of trisomy 21 and for maternal age, receiver operating characteristic curve, and likelihood ratios (defined as the ratio of the sensitivity to the false-positive rate). P <.05 was considered significant.

RESULTS

Mean gestational age at ultrasonography was 16.9 weeks' gestation (range, 14-22 weeks' gestation). Mean (+/-SD) nuchal fold thickness in fetuses with trisomy 21 (4.7 +/- 1.6 mm; n = 29) was greater than in euploid fetuses (3.2 +/- 0.9; n = 780; P <.001). Logistic regression analysis established that nuchal fold thickness was a significant predictor of trisomy 21 independent both of the other ultrasonographic markers and of maternal age (P <.001). Regression analysis showed that nuchal fold thickness was significantly correlated with gestational age among both fetuses with trisomy 21 and euploid fetuses and that the regression line of fetuses with trisomy 21 had a slope similar to that of euploid fetuses. The difference between observed and expected nuchal fold thicknesses on the basis of the biparietal diameter (as a function of gestational age) was used to obviate the confounding effect of gestational age. Differences between observed and expected nuchal fold thicknesses were then used to calculate likelihood ratios. These likelihood ratios could then be multiplied by the individual prior probability to obtain a patient-specific Down syndrome probability.

CONCLUSION

Nuchal fold thickness is correlated with gestational age in both euploid fetuses and fetuses with Down syndrome. Use of the difference between observed and expected nuchal fold thicknesses to determine likelihood ratios allows the calculation of individual posterior probabilities of Down syndrome that take into consideration both gestational age and maternal age.

Intracerebroventricular administration of copper-zinc superoxide dismutase inhibits pulsatile luteinizing hormone secretion in ovariectomized ewes

Intracerebroventricular (i.c.v.) injection of an inhibitor of nitric oxide synthase (NOS) abolishes pulsatile luteinizing hormone (LH) secretion. It has been demonstrated that structural and functional analogs of copper-zinc superoxide dismutase (Cu,Zn-SOD) inhibit neuronal NOS. The present study examined the ability of Cu,Zn-SOD to affect pulsatile LH release in the ewe. Bovine Cu,Zn-SOD was administrated into the third cerebral ventricle of unanesthetized, freely moving, ovariectomized (OVX) ewes. Jugular blood samples were taken every 15 min for 5 h before and 8 h after i.c.v. injections. In a pilot trial using three OVX ewes, i.c.v. injection of Cu,Zn-SOD at a dose of 0.5, 1.0 or 2.0 microg in 100 microl saline decreased plasma LH levels and abolished LH pulses, without affecting FSH secretion. In the main experiment, i.c.v. injection of 100 microl saline had no effect on mean LH levels and LH pulse frequency, whereas i.c.v. injection of Cu,Zn-SOD at a dose of 1 microg/100 microl saline significantly (P < 0.01) decreased mean LH levels and LH pulse frequency. In conclusion, this study provides the first evidence for the role of Cn,Zn-SOD in the control of LH secretion at the level of the brain in female mammals.

Brain damage and hypoxia in an ovine fetal chronic cocaine model

OBJECTIVE

To assess the development of brain damage in an ovine fetal chronic cocaine model. To evaluate the effect of isolated hypoxic tests on this model and to correlate hemodynamic findings (brain-sparing effect) following fetal hypoxia and the occurrence of brain damage.

STUDY DESIGN

Fifteen ewes were divided into a control group (n=7) and a cocaine treated group (n=8). From day 65 to day 134 the cocaine treated animals received a daily (5 days per week) intramuscular injection (2 mg/kg cocaine) and the control animals a placebo injection (2 ml of isotonic solution). Both groups underwent hypoxic tests (cord compression (3 min) and aortic compression (1 min)) at 90 and 134 days. In addition, anesthesia for magnetic resonance imaging (MRI) examination was carried out at 125 days. Fetal blood samples were collected during both series of hypoxic tests and the cerebral and umbilical flows were monitored by Doppler. Samples from 25 brains (control n = 10; cocaine n= 15) were processed for light and electron microscopic examination. Quantification of brain damage was done on semithin sections from six areas of cortex and germinal matrix on each fetus.

RESULTS

Similar forms of brain damage (selective neuronal loss limited to the parasaggital cortex, striatum, hippocampus and Purkinje cells) was present in both groups but lesions were more frequent in the cocaine treated group as shown by quantitative analysis for the proportion of abnormal capillaries (65% vs. 35%), capillary edema (61% vs. 34%) and abnormal neurons showing delayed neuronal degeneration (DND) (66% vs. 36%) in the cocaine and control group respectively. There was no significant difference in immunoreactivity for glial fibrillary acidic protein (GFAP) but it was more marked in the cerebellum of cocaine treated animals. Fetal blood samples showed a moderate sustained hypoxia and Doppler findings demonstrated the presence of a brain sparing effect associated with increased uterine and umbilical vascular resistance in the cocaine treated group. Nevertheless, the amplitude of the heart rate increase and cerebral dilatation was significantly lower in the cocaine treated animals.

CONCLUSION

This ovine fetal chronic cocaine model showed the presence of brain damage. Cocaine treatment seems to potentiate the effect of the hypoxic tests. Independent of the cause, the brain damage developed in the presence of brain sparing effect, strongly suggesting that this phenomenon is a sign of a pathological fetal condition and no guarantee that it will prevent tissue damage.

Cerebral MRI on fetuses submitted to repeated cocaine administration during the gestation: an ovine model

The aim of this study was to determine the role of Magnetic Resonance Imaging (MRI) in investigating fetal cerebral lesions induced by long term exposure to cocaine during sheep pregnancy. Cerebral Magnetic Resonance Imaging was performed on two groups of fetuses at 125 days of gestation (normal gestation: 145 days). The control group consisted of eight fetuses of four pregnant ewes. The study group consisted of eight fetuses of four pregnant ewes receiving daily 140 mg/kg injection of cocaine from day 60 until delivery. The following MR sequences were applied: T1-weighted FLASH, and T2-weighted Fast-Spin-Echo. Cerebral images were evaluated semi quantitatively using the following criteria: Heterogenicity, contrast between grey and white matter, contours irregularity, hyposignal, lateral ventricle sizes. The brightness distribution and homogenicity of the images were analysed by means of edge pair distributions using a new computerized method originally designed for ultrasound images analysis developed by Ultrasight inc (USA). (1) Flash T1: Heterogenic areas and irregular contours were more frequent in cocaine exposed fetuses. The contrast between grey and white matter was more important in the cocaine group. Hyposignal was found only in the cocaine group. Enlarged lateral ventricle occurred more frequently in the cocaine group. (2) Spin echo T2: The contrast between grey and white matter was higher and the contours of the brain more irregular in the cocaine group. Heterogenicity and hyposignal were also more frequent in this group but the difference with the control group was not significant. The computerized analysis of the contrast density on the cerebral images showed that 88% of the areas exceeding the reference level concerned the cocaine group, while only 14% of the areas exceeding the reference level concerned the control group. Long term exposure to cocaine induces cerebral tissue modifications, in favor of an advanced maturation and the development of hypoxic lesions. The histology of the brains confirmed in the cocaine group, the existence of hypoxic lesions with gliosis, perivascular edema and hemorrhages, and neuronal death.

Best second trimester sonographic markers for the detection of trisomy 21

We analyzed all genetic sonograms obtained during a 6 year period to establish the independent ability of the following sonographic markers of aneuploidy in the diagnosis of trisomy 21: structural anomalies, cardiac abnormalities, nuchal fold thickness of 6 mm or greater, bowel echogenicity, choroid plexus cysts, and renal pyelectasis. With the exception of bowel echogenicity and choroid plexus cysts, the sonographic markers were more common in trisomy 21 than euploid fetuses (all P < 0.001). Logistic regression analysis demonstrated that cardiac anomalies (odds ratio = 255; 95% confidence interval, 25, 2592), other structural anomalies (odds ratio = 25; 95% confidence interval, 6, 97), and nuchal fold thickness of 6 mm or greater (odds ratio = 13; 95% confidence interval, 3, 50) were the only independent predictors of trisomy 21. The false-positive rate and sensitivity were 5.3% (48 of 898) and 59.2% (13 of 22), respectively, when any of the sonographic markers significant at univariate analysis was considered, and 3.1% (28 of 898) and 54.5% (12 of 22), respectively, when any of the predictors at multivariate analysis was present. Because a considerable overlap of sonographic markers exists among trisomy 21 fetuses, use of those that are not independent predictors leads to an increase in false-positive rate without a gain in sensitivity.

Accuracy of prenatal ultrasonographic diagnosis of duplex renal system

Duplex renal system is a rare congenital anomaly of the urinary tract that can be diagnosed in utero. The purpose of this study was to establish the optimal diagnostic criteria for fetal renal duplication in a population undergoing prenatal sonographic screening. Between January 1989 and June 1997 we found 11 cases of duplex renal system, 10 of which were correctly identified in utero at a median gestational age of 28 weeks (range, 20 to 38 weeks), and one of which was a false-negative diagnosis. Prenatal diagnosis of duplex renal system can be made in utero during the second half of pregnancy in the presence of two or more of the following signs: hydronephrosis limited to one pole in a kidney with two separate, noncommunicating renal pelves; ipsilateral megaureter; and ureterocele.

Amnioreduction in emergency cerclage with prolapsed membranes: comparison of two methods for reducing the membranes

To evaluate the effectiveness of amnioreduction in pregnancies requiring emergency cerclage placement, we performed a retrospective case-control study of all consecutive pregnant women with cervical dilation and effacement with prolapse of the fetal membranes in vagina between 16 and 26 weeks' gestation, who required placement of a McDonald emergency cerclage during the period January 1991-December 1997. Duration of pregnancy prolongation, rate of delivery before 32 weeks, and duration of neonatal hospital stay were compared between women in whom amniochorionic membranes were reduced at the time of cerclage placement using only intracervical Foley balloon catheter (controls; n = 7) and those who in addition underwent amnioreduction to facilitate cerclage placement (n = 9). Statistical analysis utilized Fisher's exact test and Wilcoxon rank sum test. A p value <0.05 was considered significant. There were no procedure-related ruptures of membranes. Gestational age at cerclage and rate of positive cervico-vaginal cultures were not different between the two groups. Gestation was prolonged for a median of 100 days (range 4 to 144 days) in the amnioreduction group and 10 days (2 to 133) among controls (p = 0.3). The rate of delivery before 32 weeks was significantly lower (1/7 vs. 6/8, p = 0.03) and the duration of neonatal hospital admission significantly shorter (median 3 vs. 37 days, p = 0.001) in the amnioreduction group than among controls. The amount of amniotic fluid withdrawn ranged from 220 to 340 mL. These findings suggest that amnioreduction at the time of emergency cerclage placement is associated with a lower rate of extreme prematurity and related neonatal morbidity.

Hepatitis C virus infection is associated with a higher incidence of cholestasis of pregnancy

To investigate a possible relationship between hepatitis C virus infection and cholestasis of pregnancy, we identified all cases of cholestasis of pregnancy (145/16,271) and hepatitis C virus infection (63/16,271) between January 1992 and December 1997. Serologic screening was performed universally. The rate of cholestasis of pregnancy was greater in women whose hepatitis C virus antibodies were positive rather than negative [15.9% (10/63) vs 0.8% (135/16,208), P < 0.001]. Among women with cholestasis of pregnancy, mean (standard deviation) gestational age at onset of symptoms and at delivery was significantly lower among women whose hepatitis C virus antibodies were positive compared with negative women: 28.9 (3.2) vs 34.3 (3.5) weeks, P < 0.001 and 36.3 (0.9) vs 37.0 (1.6) weeks, P = 0.03, respectively. These findings suggest that early occurrence of cholestasis of pregnancy may be an indication for serologic testing for hepatitis C virus.

The xenotransplantation of goat and human hematopoietic cells to sheep fetuses

Hematopoietic xenografts were carried out in three experiments using goat fetal liver (44-48 days, experiments I and II) or purified human CD 34+ cells (experiment III) as the donor cells. Recipients were sheep fetuses at 41-47 days of gestation. Goat fetal liver cells were either injected without any pretreatment or stimulated by preincubation in a culturing in goat phytohemagglutinin-stimulated lymphocyte supernatant. Human CD 34+ myeloid progenitor cells were purified from bone marrow by minimacs immunomagnetic purification and cultured in medium supplemented with stem cell factor, IL3, and IL6. Goat-sheep chimerism was assessed by flow cytometry analysis (FCA) of peripheral blood and bone marrow cells using a mouse anti-goat CD 45 monoclonal antibody and by karyotype analysis of peripheral blood from goat/sheep chimeras. Human cell engraftment was assessed by polymerase chain reaction amplification of the human DAX1 gene in blood and bone marrow DNA from sheep which had received human cells. In the three experiments, a mean of 76% (26 of 34) of injected fetuses were born alive without any clinical evidence of graft-versus-host disease. Three lambs were found to be goat/sheep chimeric after flow cytometry analysis (peripheral blood and bone marrow) and karyotype (peripheral blood) analysis. Both tissues continued to express goat cells at 6 or 12 months (last assessment) depending on the experiment. No human chimerism was detected using polymerase chain reaction amplification in peripheral blood and bone marrow of any of the six sheep grafted with human cells. These data and those also obtained on other species (human, pig/sheep) show that it is possible to carry out hematopoietic xenografts using the sheep fetus as recipient provided both donor and recipient fetal cells are processed during the period of tolerance to foreign antigens.

Ultrasonographic differential diagnosis of fetal intracranial interhemispheric cysts

OBJECTIVE

Ultrasonographic differentiation between intracranial supratentorial interhemispheric pathologic cystlike lesions and those related to physiologic median structures is essential because the latter have no clinical relevance, whereas the former may carry a poor prognosis. We reviewed our experience with 19 consecutive cases of interhemispheric hypoechoic lesions without parenchymal involvement diagnosed between January 1990 and June 1997 to establish their clinical significance and provide prenatal ultrasonographic criteria to distinguish between pathologic cystlike lesions and those related to physiologic midline structures.

STUDY DESIGN

All patients underwent targeted prenatal scans of intracranial anatomy to establish the relationship between the fluid collections and the surrounding parenchymal and ventricular structures. In addition, a detailed anatomic survey was performed to rule out associated malformations. Follow-up, including neurologic examination, imaging, autopsy evaluation, or a combination was performed in all cases. Statistical analysis used the Wilcoxon rank sum test, the Fisher exact test, and the chi2 test for trend. P <.05 was considered significant.

RESULTS

Cystlike lesions related to physiologic median structures (n = 12) included enlargement of the cavum septi pellucidi (n = 3), enlargement of the cavum vergae (n = 2), and cysts of the velum interpositum (n = 7). These lesions were unilocular and had a median size of 10 mm (range 10-30 mm); they resolved in 5 cases and remained stable in the remainder. They were not associated with overt abnormalities, other than borderline ventriculomegaly in 2 cases. Pediatric follow-up (median 26 months, range 3-84 months) showed normal neurodevelopment in all cases. Pathologic cystlike lesions (n = 7) were significantly larger (median 40 mm, range 10-80 mm, P =.004) and had a significantly worsening trend, growing more at serial prenatal ultrasonographic examinations (P =.039) than fluid collections related to physiologic median structures. Moreover, prenatal ultrasonographic evidence of associated intracranial abnormalities, in the form of partial or total agenesis of the corpus callosum and overt hydrocephalus, was present in 5 of 7 cases of pathologic cystlike lesions and in none of the 12 related to physiologic structures (P =.002). Median gestational age at diagnosis was not different between those with cystlike lesions related to physiologic median structures and those with pathologic lesions (30 and 31 weeks, respectively). Among the latter group, 1 pregnancy was voluntarily terminated, 1 infant died at 4 months of age, 2 infants had neurodevelopmental delay, and 3 infants were neurologically healthy at a mean follow-up of 43 months. Cyst shunting was necessary in 5 of 6 cases.

CONCLUSIONS

Interhemispheric cystlike lesions related to physiologic structures can be prenatally distinguished from pathologic fluid collections on the basis of location, cyst size, change in size with time, and absence of associated anomalies.

What sounds reach fetuses: biological and nonbiological modeling of the transmission of pure tones

In utero transmission of external and maternal sounds has been studied in pregnant women and in an animal model of human species, the sheep. These works, especially the most recent ones, suggest that local and environmental factors interfere in such a way that signals are attenuated in a complex manner as frequency increases. The present work investigated whether a plain rubber sphere which was filled with water could be considered as a reliable nonbiological model in a study describing the characteristics of sound transmission. A sweeping pure tone, presented externally, was measured inside the rubber sphere using a high signal-to-noise ratio experimental hydrophone. A paradigmatic three components curve was observed between 100 and 20,000 Hz. In the first component of the curve (low to midfrequencies between 100 and 1,000 Hz), the intensity of the inside signal remained stable. The second component of the curve was composed of higher frequencies with the inside pressure falling gradually, demonstrating attenuation of the external signal. The third component of the curve appeared above a critical frequency, the value of which depended on several model and environment parameters. In this component, a series of rapid peaks and drops of the inside high frequency pressure was observed, indicating the presence of resonance systems. Analyses were carried out on the effects of several acoustical parameters, including: the size of the sphere, the location of the hydrophone in the sphere, the distance between the signal source and the hydrophone, the location of the external reference microphone, and the acoustical structure of the environment. These parameters allowed for the definition of their respective roles in the in-utero transmission of external sounds. These data were then compared with measurements performed within a biological model--ewes--under close acoustical settings. The comparisons confirmed the validity of the measurements, suggesting that the model may be useful in studies of sound transmission in utero.

[Minimally invasive surgery with the Port-Access method. Preliminary experience]

METHODS

Data from the initial experience of 40 patients operated on with the Port-Access technique are reported. Indication to surgery was mitral disease in 24 patients and coronary stenosis in 16 patients. Mean age was 52 years (range 32-75). Operations performed were: 8 mitral valvuloplasties, 16 valve replacements, 9 single CABG (associated with an MVR in one case), 1 double CABG, 6 triple CABG and one quadruple CABG. Coronary endarterectomy was performed in 5 patients and left atrial isolation was associated with MV surgery in 5 cases.

RESULTS

There were no operative deaths and every patient was discharged after a mean postoperative stay of 5.5 days (range 3-30). Postoperative course was complicated in 7 patients: surgical revision was necessary in 4 patients due to bleeding (through the mini-thoracotomy incision in 3 cases), 1 pacemaker was implanted for A-V block, one retained pulmonary catheter was removed through the mini-thoracotomy without the aid of cardiopulmonary bypass and in one case, there was an emergency conversion to median sternotomy due to a ventricular fibrillation unresponsive to usual resuscitative maneuvers a few hours after surgery. Some of these complications can be ascribed to the learning phase of this new technique and should disappear as experience is increased.

CONCLUSIONS

Port-Access surgery is a new minimally invasive technique that utilizes a cardiopulmonary bypass with femoral access and a specialized catheter system that provides endoaortic clamping, pulmonary artery venting and myocardial preservation with infusion of cardioplegic solution in the aortic bulb or in the coronary sinus. Major contraindications to this technique are iliac-femoral disease or severe dilatation of ascending aorta. The aim of the Port-Access technique is to combine the aesthetic and functional advantages of the minimally invasive surgery with the wide range of surgical options that cardiopulmonary bypass can afford (to operate on atrioventricular valves and perform all the CABG that the patient need), without the limitations characteristic of the classic minimally invasive direct coronary artery bypass (MIDCAB) technique.