[Characterization of the difference between filtered back projection and ordered subsets expectation maximization in spect images using the Wavelet Transform]

Efficiency of reconstruction algorithms is important to guarantee quality of Nuclear Medicine tomographic images. The algorithms belong to one of two types: analytical or statistical. The Filtered Back Projection (BP) algorithm belongs to the first group and the Ordered Subsets Expectation Maximization (OSEM) algorithm belongs to the second group. The aim of the present paper was to compare both algorithms by means of the Wavelet Transform (WT). This tool was selected because of its capability to divide the image into different frequency levels without losing information about their spatial position. The WT was applied on the Haar basis without decimation in order to compare matrixes of the same size. Attention was drawn to the relative presence of three typical perturbations: Poisson noise, annular artifacts that express a deficient correction to the planar uniformity and attenuation phenomenon. With these purposes, we studied homologue transversal slices of images of homogeneous distribution of activity. The OSEM algorithm not only greatly improves the filtering of the Poisson noise, but also diminishes the annular artifacts, mainly at the image zone that coincides with the rotation center. The intensity of the attenuation phenomenon was the same with both algorithms, except in the peripheral zone where OSEM showed a slightly higher activity than BP. These observations encourage our interest to continue applying the WT not only to identify the artifacts, but also to try to decrease their deleterious influence on Nuclear Medicine images.

[Labeling of leukocytes using stannous 99mTc-colloid in whole blood samples]

This paper presents the preparation of a radiocolloid that still makes it possible to label leukocytes using its phagocytosis capacity. Given that this function is exclusively of the white blood cells, not being exercised by other blood cells, the use of a stannous fluoride radiocolloid labeled with 99mTc (F2Sn-99mTc) was tested in order to label leukocytes in whole blood samples. Using cellular separation techniques in density gradients and acquisition of images in gamma camera of radioactivity distribution in Percol, it was observed that the white cells labeling achieved was selective and with high efficiency for leukocytes (in all cases, it was superior to 70%), optimal reproducibility, low cost and low cellular toxicity.

Discrepant results in the interpretation of HIV-1 drug-resistance genotypic data among widely used algorithms

OBJECTIVES

The aim of this study was to assess the concordance on the interpretation of HIV-1 drug-resistance genotypic data by three widely used algorithms: Stanford University Database (SU), TruGene (Visible Genetics, Canada) (VG) and VirtualPhenotype (Virco, Belgium) (VP).

METHODS

Genotypic data from 293 HIV-1-infected individuals with treatment failure was interpreted for 14 antiretroviral drugs by the three algorithms.

RESULTS

Complete concordant results among the three systems for all the drugs studied were found in 40/293 (13.7%) samples. Low concordance in the interpretation was observed for most nucleoside reverse transcriptase inhibitors (NRTIs), while results agreed highly for all nonnucleoside reverse transcriptase inhibitors (NNRTIs) and most protease inhibitors (PIs). In pair-wise comparisons, discordant interpretations between SU and VP were found in over 50% of the samples for didanosine, zalcitabine, stavudine and abacavir, and the level of disagreement between VG and VP exceeded 40% for the same drugs. Major discrepancies (high-level resistance interpretation by one algorithm with sensitive interpretation by another) were observed between VG and VP in over 10% of the cases for didanosine, zalcitabine, stavudine and abacavir. On the other hand, the three algorithms had concordant results for lamivudine in over 90% of the cases.

CONCLUSIONS

This work demonstrates the great level of discordance in the interpretation of genotyping results among algorithms, clearly showing the necessity for clinical validation. Moreover, these results suggest that a joint effort from the scientific community as well as national and international HIV societies is needed to achieve a consensus for the interpretation of genotypic data.

Cardiomyocytes induce endothelial cells to trans-differentiate into cardiac muscle: implications for myocardium regeneration

The concept of tissue-restricted differentiation of postnatal stem cells has been challenged by recent evidence showing pluripotency for hematopoietic, mesenchymal, and neural stem cells. Furthermore, rare but well documented examples exist of already differentiated cells in developing mammals that change fate and trans-differentiate into another cell type. Here, we report that endothelial cells, either freshly isolated from embryonic vessels or established as homogeneous cells in culture, differentiate into beating cardiomyocytes and express cardiac markers when cocultured with neonatal rat cardiomyocytes or when injected into postischemic adult mouse heart. Human umbilical vein endothelial cells also differentiate into cardiomyocytes under similar experimental conditions and transiently coexpress von Willebrand factor and sarcomeric myosin. In contrast, neural stem cells, which efficiently differentiate into skeletal muscle, differentiate into cardiomyocytes at a low rate. Fibroblast growth factor 2 and bone morphogenetic protein 4, which activate cardiac differentiation in embryonic cells, do not activate cardiogenesis in endothelial cells or stimulate trans-differentiation in coculture, suggesting that different signaling molecules are responsible for cardiac induction during embryogenesis and in successive periods of development. The fact that endothelial cells can generate cardiomyocytes sheds additional light on the plasticity of endothelial cells during development and opens perspectives for cell autologous replacement therapies.

CXCR4-activated astrocyte glutamate release via TNFalpha: amplification by microglia triggers neurotoxicity

Astrocytes actively participate in synaptic integration by releasing transmitter (glutamate) via a calcium-regulated, exocytosis-like process. Here we show that this process follows activation of the receptor CXCR4 by the chemokine stromal cell-derived factor 1 (SDF-1). An extraordinary feature of the ensuing signaling cascade is the rapid extracellular release of tumor necrosis factor-alpha (TNFalpha). Autocrine/paracrine TNFalpha-dependent signaling leading to prostaglandin (PG) formation not only controls glutamate release and astrocyte communication, but also causes their derangement when activated microglia cooperate to dramatically enhance release of the cytokine in response to CXCR4 stimulation. We demonstrate that altered glial communication has direct neuropathological consequences and that agents interfering with CXCR4-dependent astrocyte-microglia signaling prevent neuronal apoptosis induced by the HIV-1 coat glycoprotein, gp120IIIB. Our results identify a new pathway for glia-glia and glia-neuron communication that is relevant to both normal brain function and neurodegenerative diseases.

Neurophysiological evaluation of vigilance in epileptic patients on monotherapy with lamotrigine

OBJECTIVE

Limited research has focused to date on daytime sleepiness in epileptic patients treated with either conventional or newer antiepileptic drugs. We evaluated the level of vigilance in 15 consecutive, newly diagnosed and never medicated adult epileptic patients, receiving initial monotherapy with lamotrigine (LTG).

METHODS

Patients underwent the Multiple Sleep Latency Test (MSLT), visual reaction times (VRT) and Stanford Sleepiness Scale (SSS) on two separate occasions, i.e. before and 2 months after LTG treatment. A group of 15 age-matched healthy volunteers was taken as control.

RESULTS

At baseline, mean sleep latencies on the MSLT were comparable in epileptic patients and in controls. In patients, 2 months after monotherapy with LTG 200 mg/day, MSLT scores did not significantly change as compared with pre-treatment values. Accordingly, subjective evaluation of vigilance by the SSS and psychomotor performance by VRT were superimposable in controls and in untreated patients, and did not change in patients after LTG treatment.

CONCLUSIONS

These results suggest that in adult, newly diagnosed epileptic patients initial monotherapy with LTG does not impair vigilance.

The neural stem cells and their transdifferentiation capacity

Stem cells play a critical role during embryo and tissue formation throughout development. Thanks to their multipotentiality - i.e., the ability to give rise to different lineages of mature cells - and to their extensive capacity for self-renewal and expansive growth, stem cells can also contribute to the maintenance of tissue integrity in adulthood. Historically, it has been held that fetal and adult (somatic) stem cells are tissue-specific 'entities' whose differentiation potential is limited to the generation of mature cell types of the tissue/organ in which they reside. Yet, recent years have seen the publication of an impressive sequence of reports dealing with what is now emerging as one of the most striking functional attributes of somatic stem cells, that is, their capacity to undergo transdifferentiation. Thanks to this peculiar characteristic adult stem cells display an unexpected ability to give rise to differentiated cells of tissues and organs different from those in which they reside. This commentary briefly illustrates the characteristics of the neural stem cell and its capacity as a neuroectodermal derivative to undergo transdifferentiation, thus giving rise to differentiated cells that normally originate from the mesoderm, like blood or skeletal muscle cells.

Circulating levels of allopregnanolone, an anticonvulsant metabolite of progesterone, in women with partial epilepsy in the postcritical phase

PURPOSE

Several lines of evidence indicate that there exists a relation between ovarian hormones and epilepsy. Estrogens decrease seizure threshold and increase brain excitability, whereas progesterone has an inhibitory effect and reduces epileptiform activity. Recently considerable interest has turned to neuroactive steroids, a group of progesterone metabolites, as endogenous modulators of excitability of the central nervous system (CNS). Their ability to alter neuronal firing rapidly occurs through interaction with gamma-aminobutyric acid (GABA) A receptor complex. In a previous experience, serum allopregnanolone (3alpha-OH-5alpha-pregnan-20-one) levels were measured in 15 women with partial epilepsy in the intercritical phase, and no significant differences were found between patients and control subjects.

METHODS

To find out if there are changes in serum allopregnanolone levels after epileptic seizure, blood samples were drawn immediately, 15 min, and 6 h after a seizure in seven fertile females with partial epilepsy.

RESULTS

The most interesting finding is that allopregnanolone increases in serum during the first 15 min after partial seizures (p < 0.05) and decreases after 6 h.

CONCLUSIONS

These data are consistent with a role for allopregnanolone in the control of neuronal excitability and seizures.

Characterization of CNS precursor subtypes and radial glia

The role of radial glial cells as guides for migrating neurons is well established, whereas their role as precursor cells is less understood. Here we examined the composition of radial glial cells and their proliferation in the mouse telencephalon during development. We found that almost all radial glial cells proliferate throughout neurogenesis. They consist of three distinct subsets identified by immunostaining for the antigens RC2, the astrocyte-specific glutamate transporter (GLAST), and the brain-lipid-binding protein (BLBP). In addition, RC2, GLAST, and BLBP antisera label precursor cells with different morphologies and thereby cover almost the entire progenitor pool in the developing cerebral cortex. The subsets identified by differential expression of these antigens differ also in their transcription factor expression and cell cycle characteristics. Moreover, the content of BLBP seems correlated to the fate of the progeny. BLBP-negative precursors are detected only during neurogenesis and persist into postnatal stages solely in the rostral migratory stream, a region of ongoing neurogenesis. In contrast, an enriched population of multipotential cells, neurosphere cultures derived from the adult or embryonic telencephalon, is immunoreactive for RC2, GLAST, and BLBP. Taken together, we have identified novel, functionally distinct subsets of CNS precursor cells.

Skeletal myogenic potential of human and mouse neural stem cells

Distinct cell lineages established early in development are usually maintained throughout adulthood. Thus, adult stem cells have been thought to generate differentiated cells specific to the tissue in which they reside. This view has been challenged; for example, neural stem cells can generate cells that normally originate from a different germ layer. Here we show that acutely isolated and clonally derived neural stem cells from mice and humans could produce skeletal myotubes in vitro and in vivo, the latter following transplantation into adult animals. Myogenic conversion in vitro required direct exposure to myoblasts, and was blocked if neural cells were clustered. Thus, a community effect between neural cells may override such myogenic induction. We conclude that neural stem cells, which generate neurons, glia and blood cells, can also produce skeletal muscle cells, and can undergo various patterns of differentiation depending on exposure to appropriate epigenetic signals in mature tissues.

Delayed treatment of isthmic aortic rupture

Traumatic rupture of the thoracic aorta is a life-threatening injury with a high mortality, and is difficult to manage in polytraumatized patients. Between 1980 and 1998, 50 patients were admitted to our Department with acute traumatic aortic rupture (TAR). The site of lesion was usually isthmic (86% of patients). From 1980 to 1992, 21 patients (Group I) underwent emergency surgical repair; from 1992 to January 1998, 29 patients (Group II) underwent intensive medical treatment, except one who was haemodynamically unstable and died 8h after the trauma from a massive haemothorax before an emergency thoracotomy could be attempted. The aortic rupture was followed up by MRI or CT scan. Twenty-one patients in Group II underwent aortic repair an average of 8.6 months after the injury. In two patients the operation was expedited because of an enlarging aortic aneurysm. In Group I the postoperative mortality was 19%, three patients developed postoperative paraplegia and one acute renal failure. In Group II there were no postoperative deaths and no major complications.

Sox2 regulatory sequences direct expression of a (beta)-geo transgene to telencephalic neural stem cells and precursors of the mouse embryo, revealing regionalization of gene expression in CNS stem cells

Sox2 is one of the earliest known transcription factors expressed in the developing neural tube. Although it is expressed throughout the early neuroepithelium, we show that its later expression must depend on the activity of more than one regionally restricted enhancer element. Thus, by using transgenic assays and by homologous recombination-mediated deletion, we identify a region upstream of Sox2 (−5.7 to −3.3 kb) which can not only drive expression of a (beta)-geo transgene to the developing dorsal telencephalon, but which is required to do so in the context of the endogenous gene. The critical enhancer can be further delimited to an 800 bp fragment of DNA surrounding a nuclease hypersensitive site within this region, as this is sufficient to confer telencephalic expression to a 3.3 kb fragment including the Sox2 promoter, which is otherwise inactive in the CNS. Expression of the 5.7 kb Sox2(beta)-geo transgene localizes to the neural plate and later to the telencephalic ventricular zone. We show, by in vitro clonogenic assays, that transgene-expressing (and thus G418-resistant) ventricular zone cells include cells displaying functional properties of stem cells, i.e. self-renewal and multipotentiality. We further show that the majority of telencephalic stem cells express the transgene, and this expression is largely maintained over two months in culture (more than 40 cell divisions) in the absence of G418 selective pressure. In contrast, stem cells grown in parallel from the spinal cord never express the transgene, and die in G418. Expression of endogenous telencephalic genes was similarly observed in long-term cultures derived from the dorsal telencephalon, but not in spinal cord-derived cultures. Thus, neural stem cells of the midgestation embryo are endowed with region-specific gene expression (at least with respect to some networks of transcription factors, such as that driving telencephalic expression of the Sox2 transgene), which can be inherited through multiple divisions outside the embryonic environment.

Regulation of neuronal differentiation in human CNS stem cell progeny by leukemia inhibitory factor

The generation of diverse types of neural cells during development occurs through the progressive restriction of the fate potential of neuroepithelial progenitor cells. This process is controlled by factors intrinsic and extrinsic to the cell. While the effect of extrinsic cues on multipotent stem cells of the murine central nervous system (CNS) is becoming clearer, little is known of neural stem cells of human origin. We sought to establish the roles played by two cytokines, leukemia inhibitory (LIF) and ciliary neurotrophic factor (CNTF), and by nerve growth factor (NGF) and platelet-derived growth factor (PDGF) in regulating neuronal and astroglial differentiation in cultured embryonic diencephalic human stem cells. While NGF did not influence either neuronal or glial formation, PDGF surprisingly decreased the percentage of stem cell-generated neurons, an effect opposite to that observed in murine progenitors. Furthermore, while we confirmed the known ability of LIF and CNTF to support astroglial differentiation, we also observed that, in contrast with their murine counterparts, the fraction of CNS stem cell-generated neurons in human cultures was enhanced twofold in the presence of both cytokines. These findings highlight important differences between humans and rodents in regard to the way epigenetic cues regulate the function of neural stem cells.

Gene therapy of experimental brain tumors using neural progenitor cells

Glioblastomas, the most frequent and malignant of primary brain tumors, have a very poor prognosis. Gene therapy of glioblastomas is limited by the short survival of viral vectors and by their difficulty in reaching glioblastoma cells infiltrating the brain parenchyma. Neural stem/progenitor cells can be engineered to produce therapeutic molecules and have the potential to overcome these limitations because they may travel along the white matter, like neoplastic cells, and engraft stably into the brain. Retrovirus-mediated transfer of the gene for interleukin-4 is an effective treatment for rat brain glioblastomas. Here, we transferred the gene for interleukin-4 into C57BL6J mouse primary neural progenitor cells and injected those cells into established syngeneic brain glioblastomas. This led to the survival of most tumor-bearing mice. We obtained similar results by implanting immortalized neural progenitor cells derived from Sprague-Dawley rats into C6 glioblastomas. We also documented by magnetic resonance imaging the progressive disappearance of large tumors, and detected 5-bromodeoxyuridine-labeled progenitor cells several weeks after the injection. These findings support a new approach for gene therapy of brain tumors, based on the grafting of neural stem cells producing therapeutic molecules.

Isolation and intracerebral grafting of nontransformed multipotential embryonic human CNS stem cells

In this work, we show that the embryonic human brain contains multipotent central nervous system (CNS) stem cells, which may provide a continuous, standardized source of human neurons that could virtually eliminate the use of primary human fetal brain tissue for intracerebral transplantation. Multipotential stem cells can be isolated from the developing human CNS in a reproducible fashion and can be exponentially expanded for longer than 2 years. This allows for the establishment of continuous, nontransformed neural cell lines, which can be frozen and banked. By clonal analysis, reverse transcription polymerase chain reaction, and electrophysiological assay, we found that over such long-term culturing these cells retain both multipotentiality and an unchanged capacity for the generation of neuronal cells, and that they can be induced to differentiate into catechlaminergic neurons. Finally, when transplanted into the brain of adult rodents immunosuppressed by cyclosporin A, human CNS stem cells migrate away from the site of injection and differentiate into neurons and astrocytes. No tumor formation was ever observed. Aside from depending on scarce human neural fetal tissue, the use of human embryonic CNS stem cells for clinical neural transplantation should provide a reliable solution to some of the major problems that pertain to this field, and should allow determination of the safety characteristics of the donor cells in terms of tumorigenicity, viability, sterility, and antigenic compatibility far in advance of the scheduled day of surgery.

Epidermal and fibroblast growth factors behave as mitogenic regulators for a single multipotent stem cell-like population from the subventricular region of the adult mouse forebrain

The subventricular zone (SVZ) of the adult mammalian forebrain contains kinetically distinct precursor populations that contribute new neurons to the olfactory bulb. Because among forebrain precursors there are stem-like cells that can be cultured in the presence of mitogens such as epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF2), we asked whether distinct subsets of stem-like cells coexist within the SVZ or whether the proliferation of a single type of SVZ stem-like cell is controlled by several GFs. We show that the latter is the case. Thus cells isolated from the SVZ coexpress the EGF and FGF receptors; by quantitative analysis, the number of stem-like cells isolated from the SVZ by either FGF2 or EGF is the same, whereas no additive effect occurs when these factors are used together. Furthermore, short-term administration of high-dose [3H]thymidine in vivo depletes both the EGF- and FGF2-responsive stem-like cell populations equally, showing they possess closely similar proliferation kinetics and likely belong to the constitutively proliferating SVZ compartment. By subcloning and population analysis, we demonstrate that responsiveness to more than one GF endows SVZ cells with an essential stem cell feature, the ability to vary self-renewal, that was until now undocumented in CNS stem-like cells. The multipotent stem cell-like population that expands slowly in the presence of FGF2 in culture switches to a faster growth mode when exposed to EGF alone and expands even faster when exposed to both GFs together. Analogous responses are observed when the GFs are used in the reverse order, and furthermore, these growth rate modifications are fully reversible.

Isolation and cloning of multipotential stem cells from the embryonic human CNS and establishment of transplantable human neural stem cell lines by epigenetic stimulation

Stem cells that can give rise to neurons, astroglia, and oligodendroglia have been found in the developing and adult central nervous system (CNS) of rodents. Yet, their existence within the human brain has not been documented, and the isolation and characterization of multipotent embryonic human neural stem cells have proven difficult to accomplish. We show that the developing human CNS embodies multipotent precursors that differ from their murine counterpart in that they require simultaneous, synergistic stimulation by both epidermal and fibroblast growth factor-2 to exhibit critical stem cell characteristics. Clonal analysis demonstrates that human C NS stem cells are multipotent and differentiate spontaneously into neurons, astrocytes, and oligodendrocytes when growth factors are removed. Subcloning and population analysis show their extensive self-renewal capacity and functional stability, their ability to maintain a steady growth profile, their multipotency, and a constant potential for neuronal differentiation for more than 2 years. The neurons generated by human stem cells over this period of time are electrophysiologically active. These cells are also cryopreservable. Finally, we demonstrate that the neuronal and glial progeny of long-term cultured human CNS stem cells can effectively survive transplantation into the lesioned striatum of adult rats. Tumor formation is not observed, even in immunodeficient hosts. Hence, as a consequence of their inherent biology, human CNS stem cells can establish stable, transplantable cell lines by epigenetic stimulation. These lines represent a renewable source of neurons and glia and may significantly facilitate research on human neurogenesis and the development of clinical neural transplantation.

Cardioverter-defibrillator oversensing due to double counting of ventricular tachycardia electrograms

We report a case of a patient with idiopathic dilated cardiomyopathy and recurrent ventricular tachycardias refractory to antiarrhythmic treatment with amiodarone. A cardioverter defibrillator implantation was performed by the transvenous technique, but ventricular tachycardia detection resulted to be inappropriate because of constant double sensing of ventricular tachycardia electrograms (QRS width=250 ms). Device programmability didn't allow a satisfactory solution to this problem, therefore a more appropriate sensing system was considered. Through an anterior thoracotomy two epicardial wires were positioned and sensing by these wires, placed closer to ventricular tachycardia origin, resulted appropriate. An electrophysiologic study and subsequent follow up confirmed appropriate ICD detection of ventricular tachycardias. This case emphasizes how in some cases sensing by epicardial wires may be a solution for QRS double counting occurring with endocardial leads during ventricular tachycardia.

Evolution of post-traumatic aortic aneurysm in the subacute phase: magnetic resonance imaging follow-up as a support of the surgical timing

OBJECTIVES

A recent surgical series documented that in traumatic aortic rupture (TAR) a surgical repair postponed to the treatment of associated lesions reduced operative and overall mortality. Nevertheless some isolated cases may develop to free rupture. Until now, no imaging follow-up studies of post-traumatic aortic lesions have been reported in the early stage. The aim of this study is to analyze the behaviour of traumatic aortic ruptures in the subacute phase, in order to detect the morphological characteristics of unstable post-traumatic aneurysms.

METHODS

Twenty-five consecutive patients affected by traumatic aortic rupture (one intimal hemorrhage, 19 partial lesions and five circumferential lesions) were admitted to the department of cardiac surgery. Magnetic resonance imaging (MRI) was the imaging method used to confirm the diagnosis. No one was operated on during the acute phase. All patients were treated with beta-blockers and vasodilators as well as limited fluid administration. Delayed surgery was carried out in 18 patients at 243 days (+/-127), after the resolution of associated lesions. A scheduled MRI follow-up was performed at 7, 15 and 30 days and immediately before the operation. The parameters examined were increase of post-traumatic aneurysm, increase of periaortic hematoma and modification of the thoracic associated lesions.

RESULTS

At 30 days a 3.0 +/- 3.7 mm median increase of the aneurysm was observed, while in the subsequent period the lesions became substantially stable, resulting in a 4.4 +/- 3.6 mm increment at the end of the follow-up. The circumferential lesions presented a higher increment with respect to the partial lesions. In three cases an augmentation of 6, 7 and 12 mm was detected and surgical repair was anticipated. In 13 cases a periadventitial hematoma surrounding the aortic aneurysm decreased through the time. One case of intimal hemorrhage healed spontaneously, with no aneurysm formation. Thoracic associated lesions (pleural and pericardial effusions, rib fractures, lung focal contusions and two cases of ARDS) resolved at 30-60 days.

CONCLUSIONS

Despite common knowledge, considering TAR highly evolutive in the acute and subacute phase, this study demonstrated that this pathological entity is relatively stable if a proper pharmacological treatment is administrated. MRI follow-up is recommended in order to detect isolated cases of unstable aneurysm.

Cardiac papillary fibroelastoma of the mitral valve chordae

Papillary fibroelastomas are rare, benign, primary cardiac tumors, usually single and small. The neoplasm consists of a leafy, soft excrescence typically located on the cardiac valves. Although papillary fibroelastomas are usually an asymptomatic incidental finding at autopsy, or during cardiac operation, they are occasionally associated with embolic coronary or cerebral symptoms. A case of a patient is reported with papillary fibroelastoma of the mitral valve chordae, who presented several transitory ischemic attacks characterized by loss of conscience, visual bilateral deficit and right emiparesis. Because of their potential systemic embolization, we believe that these lesions should be always excised.

Surgical indications and timing of repair of traumatic ruptures of the thoracic aorta

BACKGROUND

The outcome of patients with acute traumatic rupture of the thoracic aorta after motor vehicle accidents is strongly conditioned by injuries to other districts. The timing of repair is controversial when the patients arrive alive to the hospital.

METHODS

A series of 42 patients with acute traumatic rupture of the thoracic aorta observed between January 1980 and June 1996 was divided into two groups: group I underwent immediate repair (21 patients) and in group II operation was performed after intensive medical treatment and management of the associated lesions and monitoring of the aortic tear.

RESULTS

The mortality in group I patients was 19% and the morbidity was more significant than in group II where no deaths were reported and complications were minor.

CONCLUSIONS

Patients with acute traumatic rupture of the thoracic aorta may have a better fighting chance if aortic operation is postponed to the most favorable moment after undergoing life-sustaining measures and management of the major associated lesions. Needless to say, evolution should be closely monitored by computed tomographic scans and magnetic resonance imaging.