La cohérence cardiaque : état des connaissances actuelles et bénéfices en psychiatrie

Le stress joue un rôle prépondérant dans un grand nombre d’affections psychiatriques. L’institut HeartMath® a développé une technique de gestion du stress appelée cohérence cardiaque. Cette technique se fonde sur une rééducation du système nerveux autonome en améliorant l’équilibre de la balance sympatho-vagale par augmentation de la Variabilité de la Fréquence Cardiaque (VFC). Par cela, on obtient une augmentation de la flexibilité de ce système nerveux autonome et ainsi une meilleure tolérance au stress.

À ce jour, la VFC peut se mesurer à l’aide d’un photopléthysmographe relié à un ordinateur permettant de visualiser le résultat (biofeedback). L’intérêt du biofeedback est la visualisation en direct de la VFC au cours de manœuvres respiratoires et techniques issues des thérapies cognitivo-comportementales Le lien entre une altération de la VFC et différentes pathologies organiques (telles que l’hypertension artérielle et l’infarctus du myocarde) mais aussi psychiatriques (telles que les troubles anxieux et thymiques) a été établi depuis plusieurs années. De même, l’administration de certaines molécules comme les bêta-bloquants et les antidépresseurs sont associés à l’augmentation de la VFC lors de l’amélioration des symptômes. Enfin, la cohérence cardiaque a déjà prouvé ses bénéfices dans le traitement de plusieurs troubles psychiatriques tels que les troubles anxieux et les troubles thymiques. Notre but est de réaliser une synthèse des connaissances actuelles sur la VFC et la cohérence cardiaque, de présenter cette thérapie, puis d’exposer ses bénéfices dans le traitement des pathologies psychiatriques allant des troubles anxieux jusqu’aux syndromes schizophréniques.

[Recent eye surgery]

The evolution of eye surgery has been truly extraordinary since the last decades, with the development of machines and techniques more and more accurate and effective. In this article will be detailed the novelties in terms of cataract surgery and refractive surgery.

Old hearts for modern investigations: CT and MR for archaeological human hearts remains

INTRODUCTION

Among 800 burials dated between the 15th and 18th centuries and found in the center of Rennes (Brittany, France), a collection of five heart-shaped lead urns was discovered. This material was studied using classical methods (external study, autopsy and histology), and also modern imaging like computed tomography (CT), magnetic resonance (MR) before and after coronary opacification. The aim of this manuscript is to describe different steps of ancient soft tissues study, especially using imaging techniques.

METHODS

The study gathered various specialists: anthropologists, archeologists, forensic pathologists, radiologists, pathologic physicians, and physicists. Imaging techniques were performed, before and after coronary opacification. Finally, hearts were autopsied and different histological samples were analyzed.

RESULTS

Only heart n°2 was too damaged to be studied. Heart n°3 was considered as normal using all investigation techniques. The study of Hearts n°s 4 and 5 revealed dilated cardiomyopathy while Heart n°1 showed important signs of diffuse hypertrophic cardiomyopathy. Different fibro lipid plaques were identified using imaging techniques, and were confirmed by histology.

CONCLUSIONS

The study of archeological soft tissues using modern imaging is possible if the material is well-preserved. This type of research can uncover principal findings, allowing scientists to establish diseases of ancient times.

Increased physical activity may be more protective for metabolic syndrome than reduced caloric intake. An analysis of estimated energy balance in U.S. adults: 2007-2010 NHANES

BACKGROUND AND AIM

The purpose of this study was to examine the association between physical activity (PA), caloric intake, and Metabolic Syndrome (MetS) in a representative sample of the United States population.

METHODS AND RESULTS

Data for 4327 adults from 2007 to 2010 NHANES were analyzed. MetS was defined using both ATPIII and AHA/NHLBI criteria. Weekly moderate and vigorous physical activity (PA) minutes from work, leisure-time, and transportation PA were used to estimate Total Energy Expenditure (TEE) from Basal Metabolic Rate (BMR) using the Harris-Benedict equation. Average total calories (KCAL) from two 24-h dietary recalls were used to compare energy intake and expenditure between subjects with and without MetS. An alpha of 0.05 was used to determine statistical differences. The age adjusted prevalence of MetS was 21.9% (95% CI 20.1-23.6) and 36.8% (34.7-39.0) using ATPIII and AHA/NHLBI criteria, respectively. The estimated population mean for KCAL/TEE was 0.83 (95% CI 0.82-0.84), and the mean for KCAL/BMR was 1.25 (95% CI 1.23-1.27). Subjects without MetS (MetS-) reported 36 ± 13 (ATPIII) and 45 ± 18 (AHA/NHLBI) more daily moderate PA minutes than subjects with MetS (MetS+). At each level of PA, MetS- consumed more calories relative to BMR and TEE than MetS+. For both normal and overweight adults, KCAL/BMR was higher for MetS- than MetS+. For all BMI groups, there were no differences between MetS- and MetS+ with respect to KCAL/TEE. Though MetS+ adults in either MetS criteria were generally less physically active, MetS- adults maintained a higher caloric intake relative to estimated energy needs.

CONCLUSIONS

These results suggest energy needs may be distorted in Metabolic Syndrome and increased physical activity may be more protective than reduced caloric intake.

Harnessing the beneficial properties of adipogenic microbes for improving human health

Obesity is associated with numerous metabolic comorbidities. Weight loss is an effective measure for alleviating many of these metabolic abnormalities. However, considering the limited success of most medical weight-management approaches in producing a sustained weight loss, approaches that improve obesity-related metabolic abnormalities independent of weight loss would be extremely attractive and of practical benefit. Metabolically healthy obesity supports the notion that a better metabolic profile is possible despite obesity. Moreover, adequate expansion of adipose tissue appears to confer protection from obesity-induced metabolic comorbidities. To this end, the 10th Stock conference examined new approaches to improve metabolic comorbidities independent of weight loss. In particular, human adenovirus 36 (Ad36) and specific gut microbes were examined for their potential to influence lipid and glucose homeostasis in animals and humans. While these microbes possess some undesirable properties, research has identified attributes of adenovirus Ad36 and gut microbes that may be selectively harnessed to improve metabolic profile without the obligatory weight loss. Furthermore, identifying the host signalling pathways that these microbes recruit to improve the metabolic profile may offer new templates and targets, which may facilitate the development of novel treatment strategies for obesity-related metabolic conditions.

Epidemiological profiles of human immunodeficiency virus and hepatitis C virus infections in Malian women: Risk factors and relevance of disparities

AIM: To document the epidemiologic patterns and risk factors of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infections in Mali in order to develop prevention means for both diseases.

METHODS: Two prospective studies were conducted in Bamako in 2009 among 1000 pregnant women (i.e., young women) who consulted six reference health centers, and in 2010, among 231 older women who attended general practice in two hospitals. Antibody tests and molecular analysis (performed only for HCV) were used to quantify the frequencies of both infections. The data were collected from patients recruited through a questionnaire. Transmission risk factors of both diseases were identified by univariate and multivariate analysis.

RESULTS: HCV seroprevalence was 0.2% for young and 6.5% for older women. HIV prevalence was similar in both populations (4.1% vs 6.1%). In older women, the analysis of risk factors highlighted an association between HCV infection and episodes of hospitalization (P < 0.01). The study did not show an association between HIV infection and the variables such as hospitalization, transfusion, tattoo, dental care, and endoscopy. A significant decrease of HIV seroprevalence was detected in young women who used condoms for contraception more than for other purposes (P < 0.01). By contrast, HIV seroprevalence was significantly increased in young women using condoms mainly to prevent sexual infections rather than for contraception (P < 0.01). No HCV/HIV coinfection was detected in our study.

CONCLUSION: Risk factors and epidemiologic data of HIV and HCV as well as the absence of co-infection strongly suggest epidemiological disparities between these diseases.

Prevalence of HIV and HCV infections in two populations of Malian women and serological assays performances

AIM

To estimate the prevalence of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infections in women in Mali and to evaluate the performance of serological assays.

METHODS

Two prospective studies were conducted in 2009 and 2010 in Mali. They concerned first, 1000 pregnant women attending six reference health centers in Bamako (Malian capital) between May 26 and June 16, 2009; and secondly, 231 women over 50 years who consulted general practitioners of two hospitals in Bamako between October 25 and December 24, 2010. Blood samples were collected and kept frozen in good condition before analysis. All samples depicted as positive using HIV/HCV enzyme immuno-assay screening assays were submitted to confirmation analysis. Molecular markers of HCV were characterized.

RESULTS

The seroprevalence of HIV and HCV in the population of pregnant women was 4.1% and 0.2% respectively. Among older women the seroprevalence was higher and similar for HIV and HCV (6.1% vs 6.5%). The anti-HIV prevalence was not different in young and older women (4.1% vs 6.1%). In contrast, the anti-HCV prevalence was higher in older compared to younger women (6.5% vs 0.2%, P < 0.01). Of 2 pregnant women who were HCV seropositive, only one was polymerase chain reaction (PCR) reactive and infected by genotype 2, with a viral load of 1600 IU/mL. Regarding older women who were HCV seropositive, 13 out of 15 were PCR reactive, infected by genotype 1 or 2. Globally HCV genotype 2 was predominant. The positive predictive value (PPV) measured with VIKIA HIV test in young women was 100% therefore significantly higher than the 87.5% measured in older women (P < 0.05). Conversely, the PPV measured with Monolisa HCV assay in older women was 88.2% and higher than the 14.3% measured in younger women (P < 0.01).

CONCLUSION

Whereas HIV prevalence was similar in both subpopulations HCV was more frequent among older women (P < 0.01). The PPV of screening assays varied with the age of the subjects.

Comparison of functional residual capacity and static compliance of the respiratory system during a positive end-expiratory pressure (PEEP) ramp procedure in an experimental model of acute respiratory distress syndrome

Introduction

Functional residual capacity (FRC) measurement is now available on new ventilators as an automated procedure. We compared FRC, static thoracopulmonary compliance (Crs) and PaO₂ evolution in an experimental model of acute respiratory distress syndrome (ARDS) during a reversed, sequential ramp procedure of positive end-expiratory pressure (PEEP) changes to investigate the potential interest of combined FRC and Crs measurement in such a pathologic state.

Methods

ARDS was induced by oleic acid injection in six anesthetised pigs. FRC and Crs were measured, and arterial blood samples were taken after induction of ARDS during a sequential ramp change of PEEP from 20 cm H₂O to 0 cm H₂O by steps of 5 cm H₂O.

Results

ARDS was responsible for significant decreases in FRC, Crs and PaO₂ values. During ARDS, 20 cm H₂O of PEEP was associated with FRC values that increased from 6.2 ± 1.3 to 19.7 ± 2.9 ml/kg and a significant improvement in PaO₂. The maximal value of Crs was reached at a PEEP of 15 cm H₂O, and the maximal value of FRC at a PEEP of 20 cm H₂O. From a PEEP value of 15 to 0 cm H₂O, FRC and Crs decreased progressively.

Conclusion

Our results indicate that combined FRC and Crs measurements may help to identify the optimal level of PEEP. Indeed, by taking into account the value of both parameters during a sequential ramp change of PEEP from 20 cm H₂O to 0 cm H₂O by steps of 5 cm H₂O, the end of overdistension may be identified by an increase in Crs and the start of derecruitment by an abrupt decrease in FRC.

Open surgery for abdominal aortic aneurysm or aorto-iliac occlusive disease--clinical and ultrasonographic long-term results

OBJECTIVE

To determine postoperative and long-term outcome and assess the relevance of abdominal ultrasound (US) after surgery for abdominal aortic aneurysm (AAA) or aortoiliac occlusive disease (AIOD).

METHODS

Records of 1704 consecutive patients having graft implantation from 1988 to 2000, either for AAA (n = 1144) or for AIOD (n = 560), were reviewed. In 2006, follow-up was 9180 patients-years for the AAA group and 5450 patients-years for the AIOD group. Among 1006 alive patients, 377 were invited randomly for US and clinical examination.

RESULTS

Hospital death occurred in 99 patients (8.6%) of the AAA group (53% in ruptured and 2% in elective AAA), and in 18 patients of the AIOD group (3.2%). There were 581 late deaths, including eight due to prosthesis infection, one to pseudo-aneurysm rupture, and one to graft thrombosis (0.6% graft-related mortality). Prosthesis thrombosis occurred in 32 patients (26 in AIOD group, p < 0.001), and graft infection in 26 (17 in AAA group, p < 0.01). Pseudoaneurysms developed in 90 patients (68 in AIOD group, p < 0.001), including eight at the proximal aortic, one at the distal aortic, two at the iliac and 79 at the femoral anastomosis. In the AAA group only, surgery was required for a new thoraco-abdominal and pararenal aneurysm in eight and four patients, respectively, while US evidenced a 26-35 and a 36-50 mm supraanastomotic aortic dilatation in 65 (32%) and in 14 (7%) patients, at a mean follow-up of 10.5 and 9.3 years, respectively.

CONCLUSION

Long-term results are good after open surgery for AAA or AIOD. Prosthesis infection and anastomotic pseudo-aneurysm are the main causes of graft-related mortality and morbidity, respectively. Because of high incidence of asymptomatic supraanastomotic aortic dilatation, all patients with a history of AAA repair should have regular abdominal US.

Effective arterial elastance as an index of pulmonary vascular load

The aim of this study was to test whether the simple ratio of right ventricular (RV) end-systolic pressure (Pes) to stroke volume (SV), known as the effective arterial elastance ( Ea), provides a valid assessment of pulmonary arterial load in case of pulmonary embolism- or endotoxin-induced pulmonary hypertension. Ventricular pressure-volume (PV) data (obtained with conductance catheters) and invasive pulmonary arterial pressure and flow waveforms were simultaneously recorded in two groups of six pure Pietran pigs, submitted either to pulmonary embolism ( group A) or endotoxic shock ( group B). Measurements were obtained at baseline and each 30 min after injection of autologous blood clots (0.3 g/kg) in the superior vena cava in group A and after endotoxin infusion in group B. Two methods of calculation of pulmonary arterial load were compared. On one hand, Ea provided by using three-element windkessel model (WK) of the pulmonary arterial system [ Ea(WK)] was referred to as standard computation. On the other hand, similar to the systemic circulation, Ea was assessed as the ratio of RV Pes to SV [ Ea(PV) = Pes/SV]. In both groups, although the correlation between Ea(PV) and Ea(WK) was excellent over a broad range of altered conditions, Ea(PV) systematically overestimated Ea(WK). This offset disappeared when left atrial pressure (Pla) was incorporated into Ea [ Ea * (PV) = (Pes − Pla)/SV]. Thus Ea * (PV), defined as the ratio of RV Pes minus Pla to SV, provides a convenient, useful, and simple method to assess the pulmonary arterial load and its impact on the RV function.

ALTERATION OF RIGHT VENTRICULAR-PULMONARY VASCULAR COUPLING IN A PORCINE MODEL OF PROGRESSIVE PRESSURE OVERLOADING

In acute pulmonary embolism, right ventricular (RV) failure may result from exceeding myocardial contractile resources with respect to the state of vascular afterload. We investigated the adaptation of RV performance in a porcine model of progressive pulmonary embolism. Twelve anesthetized pigs were randomly divided into two groups: gradual pulmonary arterial pressure increases by three injections of autologous blood clot (n=6) or sham-operated controls (n=6). Right ventricular pressure-volume (PV) loops were recorded using a conductance catheter. Right ventricular contractility was estimated by the slope of the end-systolic PV relationship (Ees). After load was referred to as pulmonary arterial elastance (Ea) and assessed using a four-element Windkessel model. Right ventricular-arterial coupling (Ees/Ea) and efficiency of energy transfer (from PV area to external mechanical work [stroke work]) were assessed at baseline and every 30 min for 4 h. Ea increased progressively after embolization, from 0.26+/-0.04 to 2.2+/-0.7 mmHg mL(-1) (P<0.05). Ees increased from 1.01+/-0.07 to 2.35+/-0.27 mmHg mL(-1) (P<0.05) after the first two injections but failed to increase any further. As a result, Ees/Ea initially decreased to values associated with optimal SW, but the last injection was responsible for Ees/Ea values less than 1, decreased stroke volume, and RV dilation. Stroke work/PV area consistently decreased with each injection from 79%+/-3% to 39%+/-11% (P<0.05). In response to gradual increases in afterload, RV contractility reserve was recruited to a point of optimal coupling but submaximal efficiency. Further afterload increases led to RV-vascular uncoupling and failure.

[Surgical left ventricular remodelling via endoventriculoplasty: clinical observation]

A case of dilated ischemic cardiomyopathy, with severely impaired left ventricular systolic function, treated by endoventriculoplasty and CABG, is reported. The authors discuss the modern concepts regarding the surgical treatment of large anterior asynergic scars following occlusion of the LAD. Since there are more similarities between akinesia and dyskinesia than previously thought, the endoventriculoplasty of DOR may constitute a new way to surgically remodel the left ventricle in dilated cardiomyopathies with large anterior akinesia. This surgery significantly improves the ventricular function and the overall patients' prognosis at short and mid term follow up.

Use of the Internet by parents of children with congenital heart disease

OBJECTIVE

We sought to document the prevalence of Internet access and usage patterns among families with children diagnosed with congenital heart disease.

MATERIAL AND METHODS

A questionnaire was administered to the parents of 509 unselected children with congenital heart disease attending the outpatient cardiac clinic.

RESULTS

389 questionnaires were completed. The most common source for acquiring medical information was via the paediatric cardiologist (83%), the family doctor (53%), the general paediatrician (40%) and the Internet (15%). Among the 238 families with Internet access (62%), the most common locations for Internet access were home (74%) and work (33%), and 84 used the Internet to obtain information related to their child's cardiac diagnosis, mostly at the time of diagnosis. Two-thirds of these families considered finding information related to the cardiac diagnosis as easy or very easy, and found this information helpful or very helpful.

CONCLUSION

A quarter of the families uses the Internet to find information about their child's congenital heart disease. Internet use in this patient population is expected to increase and our vigilance in providing accurate references and in identifying inaccurate information is of paramount importance.

Severe pulmonary embolism:pulmonary artery clot load scores and cardiovascular parameters as predictors of mortality

PURPOSE

To retrospectively evaluate pulmonary artery (PA) clot load scores and computed tomographic (CT) cardiovascular parameters as predictors of mortality in patients with severe pulmonary embolism (PE).

MATERIALS AND METHODS

Institutional review board approval was obtained with waiver of informed consent. A total of 82 consecutive patients (42 women, 40 men; mean age+/-standard deviation, 61 years+/-15) were admitted to the intensive care unit for PE-related conditions and were evaluated by using CT pulmonary angiography. Two independent readers who were blinded to clinical outcome quantified PA clot load by using four scoring systems. Cardiovascular measurements included right ventricular (RV) and left ventricular (LV) short-axis measurements; RV short axis to LV short axis (RV/LV) ratios; main PA, ascending aorta, azygos vein, and superior vena cava diameters; and main PA diameter to aorta diameter ratios. Reflux of contrast medium into the inferior vena cava, leftward bowing of the interventricular septum, pleural or pericardial effusion, pulmonary consolidation, infarct, platelike atelectasis, and mosaic ground-glass opacity were also recorded. Results were correlated with patient outcome during hospital stay by using the Wilcoxon rank sum and chi2 tests.

RESULTS

Twelve patients died within 1-14 days. RV and LV short axis; RV/LV ratio; azygos vein, superior vena cava, and aorta diameters; and contrast medium reflux into the inferior vena cava were significantly different between survivors and nonsurvivors (P<.05). No significant relationship was found between PA clot load and mortality rate. RV/LV ratio and azygos vein diameter allowed correct prediction of survival in 89% of patients (P<.001).

CONCLUSION

RV/LV ratio and azygos vein diameter are predictors of mortality in patients with severe PE.

Computed tomographic pulmonary angiography and prognostic significance in patients with acute pulmonary embolism

BACKGROUND

Patients with acute pulmonary embolism (APE) present with a broad spectrum of prognoses. Computed tomographic pulmonary angiography (CTPA) has progressively been established as a first line test in the APE diagnostic algorithm, but estimation of short term prognosis by this method remains to be explored.

METHODS

Eighty two patients admitted with APE were divided into three groups according to their clinical presentation: pulmonary infarction (n = 21), prominent dyspnoea (n = 29), and circulatory failure (n = 32). CTPA studies included assessment of both pulmonary obstruction index and right heart overload. Haemodynamic evaluation was based on systolic aortic blood pressure, heart rate, and systolic pulmonary arterial pressure obtained non-invasively by echocardiography at the time of diagnosis of pulmonary embolism.

RESULTS

The mortality rate was 0%, 13.8% and 25% in the three groups, respectively. Neither the pulmonary obstruction index nor the pulmonary artery pressure could predict patient outcome. In contrast, a significant correlation with mortality was found using the systolic blood pressure (p<0.001) and heart rate (p<0.05), as well as from imaging parameters including right to left ventricle minor axis ratio (p<0.005), proximal superior vena cava diameter (p<0.001), azygos vein diameter (p<0.001), and presence of contrast regurgitation into the inferior vena cava (p = 0.001). Analysis from logistic regression aimed at testing for mortality prediction revealed true reclassification of 89% using radiological variables.

CONCLUSION

These results suggest that CTPA quantification of right ventricular strain is an accurate predictor of in-hospital death related to pulmonary embolism.

Cyclic administration of pamidronate to treat osteoporosis in children with cerebral palsy or a neuromuscular disorder: a clinical study

Eighteen osteoporotic (Z-score at or below 2.5) nonambulatory children with cerebral palsy or a neuromuscular disorder received cyclic intravenous administration of pamidronate. One year after treatment, bone densitometry showed an improvement in all patients: a mean increase of 13% +/- 15% standard deviation (SD) (p < 10(-5)) on the global data, and a mean increase of 27% +/- 15% (p < 10(-5)) on the most significant area for each individual patient. Clinical improvement was found in all patients, with a decrease in pain on manipulation, and no new fractures. No major adverse effects were reported. Cyclic intravenous administration of pamidronate is a useful tool in the treatment of osteoporosis in these children.

Effects of dobutamine on left ventriculoarterial coupling and mechanical efficiency in acutely ischemic pigs

This study investigated the effects of dobutamine on left ventriculoarterial (VA) coupling and mechanical efficiency in acutely ischemic pigs. Experiments were performed in 12 pigs in which vascular properties, including peripheral resistance (R2), compliance (C), and arterial elastance (Ea), were estimated with a windkessel model, and left ventricular (LV) function by the slope (Ees) of the end-systolic pressure-volume relationship (ESPVR) and stroke work (SW). VA coupling was defined as Ees/Ea, and mechanical efficiency as SW/pressure-volume area (PVA). In all animals, the left anterior descending coronary artery was ligated after basal measures. The animals were then randomly divided into 2 groups: group CTRL (n = 6) was followed for 180 minutes without other intervention, whereas group DOBU (n = 6) was infused with dobutamine (5 microg x kg(-1) x min(-1)) starting after T60 measures. Coronary occlusion induced a rightward shift of ESPVR and a decrease in Ees from 3.67 +/- 0.33 to 1.92 +/- 0.20 mm Hg x mL(-1), while Ea changed from 3.33 +/- 0.56 to 4.65 +/- 0.29 mm Hg x mL, R2 from 1.72 +/- 0.30 to 2.38 +/- 0.16 mm Hg x s x mL(-1), and C from 0.78 +/- 0.16 to 0.46 +/- 0.08 mL x mm Hg(-1). This altered VA coupling from 1.22 +/- 0.11 to 0.44 +/- 0.07. SW decreased from 4056 +/- 223 to 2372 +/- 122 mm Hg x mL, and PVA and SW/PVA decreased from 5575 +/- 514 to 4830 +/- 317 mm Hg x mL, and from 0.76 +/- 0.04 to 0.49 +/- 0.03, respectively. In group DOBU, dobutamine restored Ees and the position of ESPVR to baseline values, while Ea decreased to 3.39 +/- 0.34 mm Hg x mL(-1) because of an R2 decrease to 1.60 +/- 0.24 mm Hg x s x mL(-1). VA coupling was restored. SW and PVA increased to 3833 +/- 180 mm Hg x mL and to 7498 +/- 442 mm Hg x mL, respectively, while SW/PVA was unchanged. In ischemic pigs, dobutamine restored VA coupling through an increase in LV contractility and decrease in arterial elastance as a result of peripheral vasodilatation. However, myocardial oxygen consumption was increased, and mechanical efficiency impaired.

Defective remethylation of homocysteine is related to decreased synthesis of coenzymes B2 in thyroidectomized rats

We investigated the influence of hypothyroidism on homocysteine metabolism in rats, focusing on a hypothetical deficient synthesis of FAD by riboflavin kinases. Animals were allocated in control group (n = 7), thyroidectomized rats (n = 6), rats with diet deficient in vitamin B2, B9, B12, choline and methionine (n = 7), thyroidectomized rats with deficient diet (n = 9). Homocysteine was decreased in operated rats (2.6 +/- 1.01 vs. 4.05 +/- 1.0 mumol/L, P = 0.02) and increased in deficient diet rats (29.56 +/- 4.52 vs. 4.05 +/- 1.0 micromol/L, P = 0.001), when compared to control group. Erythrocyte-Glutathione-Reductase-Activation-Coefficient (index of FAD deficiency) was increased in thyroidectomized or deficient diet rats (P = 0.004 for both). Methylenetetrahydrofolate-reductase and methionine-synthase activities were decreased in thyroidectomized rats but not in those subjected to deficient diet. Cystathionine-beta-synthase was increased only in operated rats. Taken together, these results showed a defective re-methylation in surgical hypothyroidism, which was due in part to a defective synthesis of vitamin B2 coenzymes. This defective pathway was overcompensated by the increased Cystathionine-beta-synthase activity.

Comparison of the Effects of Propofol and Pentobarbital on Left Ventricular Adaptation to an Increased Afterload

The purpose of this study was to compare the hemodynamic effects of pentobarbital and propofol and their effects on cardiovascular adaptation to an abrupt increase in left ventricular afterload. Experiments were performed in 12 open-chest pigs instrumented for measurement of aortic pressure and flow, and left ventricular pressure and volume. In one group (n = 6), anesthesia was obtained with sodium pentobarbital (3 mg x kg(-1) x h(-1)), and, in the second group B (n = 6), with propofol (10 mg x kg(-1) x h(-1)). Both groups received sufentanil (0.5 microg x kg(-1) x h(-1)) and pancuronium bromide (0.1 mg x kg(-1)). Left ventricular function was assessed by the slope of end-systolic pressure-volume relationship and stroke work. After baseline recordings, left ventricular afterload was increased by aortic banding. The cardiovascular adaptations triggered by the aortic banding, such as tachycardia, vasoconstriction, and augmentation of myocardial contractility were prevented with propofol, suggesting interference with the baroreflex. Increase in left ventricular afterload decreased mechanical efficiency, regardless of anesthetic agent. These results showed that pentobarbital at 3 mg x kg(-1) x h(-1) has less deleterious hemodynamic effects than propofol at 10 mg x kg(-1) x h(-1).

Comparison between single-beat and multiple-beat methods for estimation of right ventricular contractility

OBJECTIVE

It was investigated whether pharmacologically induced changes in right ventricular contractility can be detected by a so-called "single-beat" method that does not require preload reduction.

DESIGN

Prospective animal research.

SETTING

Laboratory at a large university medical center.

SUBJECTS

Eight anesthetized pigs.

INTERVENTIONS

End-systolic elastance values obtained by a recently proposed single-beat method (Eessb) were compared with those obtained using the reference multiple-beat method (Eesmb).

MEASUREMENTS AND MAIN RESULTS

Administration of dobutamine increased Eesmb from 1.6 +/- 0.3 to 3.8 +/- 0.5 mm Hg/mL (p =.001), whereas there was only a trend toward an increase in Eessb from 1.5 +/- 0.2 to 1.7 +/- 0.4 mm Hg/mL. Esmolol decreased Eesmb from 1.7 +/- 0.3 to 1.1 +/- 0.2 mm Hg/mL (p =.006), whereas there was only a trend for a decrease in Eessb from 1.5 +/- 0.2 to 1.3 +/- 0.1.

CONCLUSIONS

The present method using single-beat estimation to assess right ventricular contractility does not work as expected, since it failed to detect either increases or decreases in right ventricular contractility induced by pharmacologic interventions.

Plasmatic cystatin C for the estimation of glomerular filtration rate in intensive care units

OBJECTIVE

To compare the sensitivity of cystatin C and creatinine in detecting decreased glomerular filtration rate.

DESIGN

Prospective observational study.

SETTING

Medical intensive care unit at a university hospital.

PATIENTS AND PARTICIPANTS

Fourteen patients hospitalised in a medical intensive care unit.

INTERVENTIONS

Cystatin C and creatinine plasmatic levels were measured in 40 blood samples taken with an interval of at least 24 h.

MEASUREMENTS AND RESULTS

Glomerular filtration rate was estimated by creatinine clearance using 24-h urine collection and the classical Cockcroft-Gault equation. The ability of cystatin C to detect a glomerular filtration rate under 80 ml/min per 1.73 m(2) was significantly better than that of creatinine ( p<0.05).

CONCLUSIONS

Cystatin C, a new plasmatic marker of renal function, could be used to detect renal failure in intensive care in the future.

Effects of increased afterload on left ventricular performance and mechanical efficiency are not baroreflex-mediated

OBJECTIVE

To assess baroreflex intervention during increase in left ventricular afterload, we compared the effects of aortic banding on the intact cardiovascular system and under hexamethonium infusion.

METHODS

Six open-chest pigs, instrumented for measurement of aortic pressure and flow, left ventricular pressure and volume, were studied under pentobarbital-sufentanil anesthesia. Vascular arterial properties were estimated with a four-element windkessel model. Left ventricular contractility was assessed by the slope of end-systolic pressure-volume relationship.

RESULTS

The effects of aortic banding on mechanical aortic properties were unaffected by autonomic nervous system inhibition. However, increase in peripheral arterial vascular resistance and in heart rate were prevented by hexamethonium. Aortic banding increased left ventricular contractility and stroke work. Left ventricular-arterial coupling remained unchanged, but mechanical efficiency was impaired. These ventricular changes were independent of baroreflex integrity.

CONCLUSIONS

Our results demonstrate that an augmentation in afterload has a composite effect on left ventricular function. Left ventricular performance is increased, as demonstrated by increase in contractility and stroke work, but mechanical efficiency is decreased. These changes are observed independently of baroreflex integrity. Such mechanisms of autoregulation, independent of the autonomic nervous system, are of paramount importance in heart transplant patients.

Predictors of early and late outcome of percutaneous coronary intervention in octogenarians

OBJECTIVE

To evaluate the short and long-term results of percutaneous coronary interventions (PCI) in patients aged 80 years or older and to identify predictors of event-free survival.

METHODS AND RESULTS

Clinical and angiographic data from all patients undergoing percutaneous coronary intervention in our institution are prospectively collected and stored in a computerized database. The clinical and angiographic characteristics of all patients aged 80 years or older undergoing percutaneous coronary intervention between January 1994 and December 1999 were analysed retrospectively. Follow-up was obtained by interview or through the referring physician. One hundred and fifty-eight patients aged 80 years or older (median: 83.4; range: 80.2-92.2) underwent percutaneous coronary intervention in our institution during the study period. The initial angiographic success rate was 92%. In-hospital mortality was 8.2% and procedural success 84.8%. One-year and two-year survival were 81% and 72.2% respectively, while event free survival at 1 year and 2 years was 65.8% and 57%. Using the Cox proportional hazards method, we identified incomplete revascularization and low left ventricular ejection fraction (LVEF) as predictors of death at 2 years. Complete revascularization and stenting were independent predictors of 2-year event-free survival.

CONCLUSION

Percutaneous coronary intervention can be performed safely in octogenarians. Complete revascularization, stenting and preserved left ventricular ejection fraction were independent predictors of better outcome in this population.

Alteration of left ventriculo-arterial coupling and mechanical efficiency during acute myocardial ischemia

AIM

Myocardial revascularisation being frequently performed during acute myocardial ischemia, in a hostile hemodynamic environment, we evaluated left ventriculo-arterial (VA) coupling, left ventricular (LV) mechanical efficiency, and the mechanical properties of the systemic vasculature during acute myocardial ischemia.

METHODS

In 6 pigs, vascular properties [characteristic impedance (R(1)), peripheral resistance (R(2)), compliance (C), inductance (L), arterial elastance (E(a))] were estimated with a windkessel model. LV function was assessed by the slope (E(es)) of end-systolic pressure-volume relationship (ESPVR), and stroke work (SW) - end-diastolic volume (EDV) relation. Pressure-volume area (PVA) was referred to as myocardial oxygen consumption. VA coupling was defined as E(es)/E(a), and mechanical efficiency as SW/PVA. After baseline recordings, the left anterior descending coronary artery was ligated and hemodynamic measures obtained every 30 minutes for 3 hours. Data are expressed as mean (SEM).

RESULTS

Coronary occlusion induced an ESPVR rightward shift, and decreased E(es) from 3.67 (0.33) to 1.92 (0.20) mmHg/ml and the slope of the SW - EDV relationship from 72.3 (3.4) to 40.4 (4.5) mmHg (p<0.001), while E(a) increased from 3.33 (0.56) to 4.65 (0.29) mmHg/ml (p<0.005). This was responsible for a dramatic alteration of VA coupling from 1.22 (0.11) to 0.44 (0.07), (p<0.001). While R2 increased from 1.72 (0.30) to 2.38 (0.16) mmHg x s x ml(-1) (p<0.05) and C decreased from 0.78 (0.16) to 0.46 (0.08) ml/mmHg (p<0.05), R(1) and L were unchanged. Coronary occlusion decreased SW from 4056 (223) to 2580 (122) mmHg.ml (p<0.001), while PVA and SW/PVA decreased from 5575 (514) to 4813 (317) mmHg x ml (NS), and from 0.76 (0.04) to 0.57 (0.03) (p<0.001), respectively.

CONCLUSION

Acute myocardial ischemia severely altered left ventriculo-arterial coupling and LV mechanical efficiency. Impaired left VA coupling was due to a combination of augmented arterial elastance, secondary to early vasoconstriction later associated with decreased arterial compliance, and decreased LV contractility.

Brown Norway rat ovalbumin-specific immunoglobulin E antibodies increase the human basophil expression of CD63 marker

Anaphylactic shock is an immunoglobulin E (IgE)-dependent hypersensitivity. Biological tests like leucocyte histamine release (LHR) and human basophil activation (HBA), frequently used in human allergy, reflect both the amount of IgE fixed on cells and the cellular reactivity. To assess whether serum-specific IgE from Brown Norway (BN) rats prepared for ovalbumin (OVA)-induced anaphylactic shocks can activate human basophils which has a potential interest in experimental allergy: such a test could rapidly assert an IgE sensitization in laboratory animals genetically T-helper 2 (Th2)-predisposed. Rats (n = 39) were immunized three times (day 0, day 5 and day 21) with OVA injected subcutaneously. One week after the third immunization, a shock was induced with an intravenous (i.v.) bolus of OVA. Sensitization was assessed by passive cutaneous anaphylaxis (PCA) test and dosages of serum IgE antibodies anti-OVA by enzyme-linked immunosorbent assay. Blood basophils were counted before and during the shock. Before the shock induction (at day 21), an LHR test was performed on rat blood, and human basophils were sensitized with rat sera. HBA was demonstrated by the increase in the percentage of cells expressing CD63 antigen membrane, measured by flow cytometry. Twenty-one days after the first subcutaneous (s.c.) immunization, the rat serum induced a significant HBA. HBA was observed neither with the same serum previously heated nor with the serum from nonimmunized rats (NIRs). OVA-specific IgEs were significantly increased in immunized rat (IR) serum. The PCA test was negative when the serum was previously heated (56 degrees C). We never observed any circulating basophils, and LHR test was negative. After OVA i.v. administration, all IRs died rapidly. HBA testing strongly suggests a mediation by specific IgE in the increase of CD63 in BN rats. Thus, HBA test seems useful in assessing whether an experimental allergy was induced in animals genetically predisposed to an immune response, Th2-mediated, like BN rat. We also conclude that rat basophil activation does not participate in the histamine release during anaphylactic shock in sensitized BN rats.

Heart rate response profiles to tilting in healthy and unhealthy neonates

BACKGROUND

Clinical observations suggest the immaturity of the neonate's ability to respond appropriately to cardio-respiratory challenges and tilt test could help in detecting autonomic dysfunction in neonates.

MATERIAL/METHODS

Heart rate (HR) responses following a 45 degrees head-up tilt during sleep were measured within the first week of adjusted age in 7 healthy full-term neonates, 7 healthy preterm infants and 5 neonates with abstinence syndrome.

RESULTS

The tilt and the return to the horizontal position generally provoked a sustained or transient tachycardia, or a flat response in healthy full-term neonates and in preterm neonates, but a sustained or transient bradycardia in neonates with abstinence syndrome.

CONCLUSIONS

When compared to previous studies in older infants, our data point to the immaturity of the neonate's ability to respond appropriately to cardio-respiratory challenges. No difference is noted between full-term and preterm neonates. The altered HR response in neonates with abstinence syndrome suggests an autonomic dysregulation in this group.

Cardiac surgery in octogenarians; peri-operative outcome and long-term results

AIMS

Because the elderly are increasingly referred for operation, we reviewed the results of cardiac surgery in patients of 80 years or older.

METHODS AND RESULTS

Records of 182 consecutive octogenarians who had had cardiac operations between 1992 and 1998 were reviewed. Follow-up was 100% complete. Seventy patients had coronary grafting (CABG), 70 aortic valve replacement, 30 aortic valve replacement+CABG, and 12 mitral valve repair/replacement. Rates of hospital death, stroke, and prolonged stay (>14 days) were as follows: CABG: 7 (10%), 2 (2.8%) and 41 (58%); aortic valve replacement: 6 (8.5%), 2 (2.8%) and 32 (45.7%); aortic valve replacement+CABG: 8 (26.5%), 1 (3.8%) and 14 (46.6%); mitral valve repair/replacement: 3 (25%), 1 (8.3%) and 5 (41.6%). Multivariate predictors (P<0.05) of hospital death were New York Heart Association functional class, urgent procedure, prolonged cardiopulmonary bypass time, and, after aortic valve replacement, previous percutaneous aortic valvuloplasty. Ascending aortic atheromatous disease was predictive of stroke, while pre-operative myocardial infarction was predictive of prolonged hospital stay. Actuarial 5-year survival was as follows: CABG, 65.8+/-8.8%; aortic valve replacement, 63.6+/-7.1%; aortic valve replacement+CABG, 62.4+/-6.8%; mitral valve repair/replacement, 57.1+/-5.6%; and total, 63.0+/-5.6%. Multivariate predictors of late death were pre-operative myocardial infarction, and urgent procedure. Ninety percent of long-term survivors were in New York Heart Association class I or II, and 87% believed having a heart operation after age 80 years was a good choice.

CONCLUSION

Cardiac operations are successful in most octogenarians with increased hospital mortality, and longer hospital stay. Long-term survival and quality of life are good.

Early stage results after oesophageal resection for malignancy - colon interposition vs. gastric pull-up

OBJECTIVE

The aims of our study were to determine if using the colon as a digestive transplant after oesophagectomy for cancer was associated with increased postoperative complications, and to assess the impact of preoperative radiochemotherapy on postoperative hospital outcome.

METHODS

From January 1990 to December 1998, 130 patients underwent oesophageal resection for malignancy. There were 103 males and 27 females (age: 61.3+/-11.5 years). Indications were squamous cell carcinoma in 69 patients and adenocarcinoma in 61. Preoperatively 30 patients (eight in stage IIB, 18 in stage III, and four in stage IV) received radiochemotherapy. There were 84 subtotal oesophagectomies, with anastomosis in the neck in 44 patients and at the thoracic inlet in 40, and 46 distal oesophageal resections. Digestive continuity was restored with the stomach in 92 patients (age: 63.4+/-10.2 years) and the colon in 38 (age: 52.3+/-12.8 years). With the exception of age (P<0.0001), there was no significant preoperative difference between gastric and colonic groups.

RESULTS

Hospital mortality was 8.5% (11 patients), decreasing from 18.5% (before 1993) to 3.8% (since 1993). One patient (2.5%) died in the colonic graft group and ten (11%) in the gastric pull-up group (P=0.17). Postoperative complications occurred in 40 patients (31%), respectively, in ten (26%) and 30 (33%) patients after colonic and gastric transplants (P=0.48), and were pulmonary insufficiency or infection in 29 patients, anastomotic fistula in six, myocardial infarction in five, recurrent nerve palsy in four, renal insufficiency in three, and cerebrovascular accident in one. All fistulas occurred in the gastric pull-up group. The incidence of postoperative pulmonary complications was 70% (21/30 patients) in the subgroup who received preoperative radiochemotherapy, as compared to 11% (5/44 patients) in the subgroup of comparable staging, but without preoperative treatment (P<0.001).

CONCLUSIONS

Colonic grafts are not associated with increased postoperative mortality or complications. Our results suggest that preoperative neoadjuvant treatment significantly increases postoperative pulmonary complications.

Heart rate variability and the outcome of head-up tilt in syncopal children

OBJECTIVE

This study evaluated autonomic nervous system function in 5 young (6-10 years old) and 5 older (10-15 years) children with recurrent episodes of neurally mediated syncope and a positive tilt-test result, 10 with syncope but a negative test result and 30 age-matched healthy volunteers.

METHODS

Time- (SDNN, SDNNi, SDANNi, rMSSD, pNN50) and frequency-domain indices (LF, HF, LF/HF) of heart rate variability (HRV) were measured during a 24-hour Holter recording and for 5 min. segments before and during 90 degrees head-up tilt (tests lasted 30 min. or until syncope occurred).

RESULTS

24-hour HRV-indices were within the normal range for all syncopal patients. Mean RR interval and HRV-indices, except LF/HF, were higher in the older children with a positive test result before they were tilted and during the first 5 min. of head-up tilt. HRV-indices tended to be lower after tilt in the younger children with a positive test result. SDNN and LF in older children with a positive test result and LF/HF in the younger ones increased during the 5 min preceding the syncope. No difference was observed between syncopal children with a negative test result and controls.

CONCLUSION

This study confirms that patients with vasovagal syncope have no chronic differences from normal subjects in autonomic nervous system activity. The modulation of the autonomic tone during head-up tilt is abnormal in children who faint during the test, but younger and older patients respond differently to the orthostatic stimulus.

Radiology in the diagnosis and therapy of gastrointestinal bleeding

Major breakthroughs in catheter and guidewire design as well as improvements in angiographic x-ray equipment currently allow interventional radiologists to diagnose massive life-threatening upper and lower GI hemorrhage and to stop the bleeding safely and effectively using superselective catheterization and microcoil embolization. For chronic or recurrent GI bleeding, when endoscopy is unrevealing or equivocal, barium studies, CT scanning, nuclear medicine studies, and angiography can help determine the cause of bleeding. A multidisciplinary approach, including the gastroenterologist, radiologist, and surgeon, is extremely helpful in managing GI bleeding, particularly in high-risk patients or patients presenting as diagnostic dilemmas.

Increased aortic compliance maintains left ventricular performance at lower energetic cost

OBJECTIVE

The aim of this study was to investigate left ventricular contractility and energetic cost of cardiac ejection under conditions of acute increase in aortic compliance.

METHODS

In six anaesthetized pigs, ascending aortic compliance was increased by adding a volume chamber in parallel to the ascending aorta. Systemic vascular parameters, including characteristic impedance, peripheral resistance, total vascular compliance, and inertance, were estimated with a four-element windkessel model. Arterial elastance was derived from these parameters. Left ventricular systolic function was assessed by end-systolic pressure-volume relationship (end-systolic elastance), and stroke work. Pressure-volume area was used as a measure of myocardial oxygen consumption. Heart rate remained constant during the experimentation.

RESULTS

Adding the aortic volume chamber significantly increased vascular compliance from 0. 95+/-0.08 to 1.17+/-0.06 ml/mmHg (P<0.01), while inductance, characteristic impedance, peripheral resistance, and arterial elastance remained statistically at basal values, respectively 0. 0020+/-0.0003 mmHg.s(2)/ml, 0.105+/-0.009 mmHg.s/ml, 1.27+/-0.12 mmHg.s/ml, and 2.43+/-0.21 mmHg/ml. During the same interval, stroke work and pressure-volume area decreased respectively from 2700+/-242 to 2256+/-75 mmHg.ml (P<0.01), and from 3806+/-427 to 3179+/-167 mmHg.ml (P<0.01). Stroke work and pressure-volume area decreased at matched end-diastolic volumes. In contrast, end-systolic elastance, ejection fraction, and stroke volume remained statistically unchanged, respectively at 2.29+/-0.14 mmHg/ml, 48.1+/-2.1 %, and 32. 4+/-1.7 ml.

CONCLUSIONS

These data suggest that, when facing an increased aortic compliance, the left ventricle displays unchanged contractility, but the energetic cost of cardiac ejection is significantly decreased. These data may be of clinical importance when choosing an artificial prosthesis for ascending aortic replacement.

Aortic valve replacement in the octogenarians: perioperative outcome and clinical follow-up

OBJECTIVES

To determine long-term results of aortic valve replacement (AVR) in patients 80 years old or older, and assess the factors influencing perioperative outcome.

METHODS

Data were reviewed on 83 consecutive octogenarians, undergoing aortic valve replacement between 1992 and 1997. There were 66 women and 17 men (mean age: 82.8 years). Fifty-seven patients (69%) were in New York Heart Association (NYHA) class III-IV and six had previous myocardial infarction. Three patients had previous percutaneous aortic valvuloplasty. There were 19 urgent procedures (23%). Coronary artery bypass grafting (CABG) was performed on 21 patients (25%). Possible influence of preoperative and operative variables on early and late mortality was performed with univariate and multivariate statistical analysis, and survival was estimated with the Kaplan-Meier method.

RESULTS

Operative mortality was 13% (9% for AVR, 24% for AVR-CABG). Postoperative complications were respiratory failure in 19 patients, atrial fibrillation in 19, hemodialysis in four, myocardial infarction in four and stroke in two patients. Five patients required pacemaker insertion for permanent atrioventricular block. Median hospital stay and intensive care unit stay were 19.8 +/- 12.2 days and 7.9 +/- 3.4 days, respectively. Multivariate predictors of hospital death (P < 0.05) were percutaneous aortic valvuloplasty, NYHA class IV, and urgent procedure. Mean follow-up was 26.5 months. Survival at 1, 2, and 5 years was 98.5 +/- 1.4% (63 patients at risk), 93.4 +/- 3.2% (47 patients at risk), and 78.2 +/- 6.9% (six patients at risk), respectively. Preoperative myocardial infarction and urgent procedure were independent predictors of late death. At most recent follow-up, 91% were angina free and 81% were in class I-II.

CONCLUSIONS

Aortic valve replacement in octogenarians can be performed with acceptable mortality. These results stress the importance of early operation on elderly patients with aortic valve disease. Both long-term survival and functional recovery are excellent.

Assimilation of [57Co]-labeled cobalamin in human fetal gastrointestinal xenografts into nude mice

Cobalamin (Cbl) and its Cbl-binding proteins are present in amniotic fluid. Because amniotic fluid is swallowed by the embryo-fetus, we studied the ability of Cbl to be transported and metabolized across the embryo-fetal digestive tract. Human embryonic stomachs and intestines were transplanted into nude mice. The basal secretion of Cbl-binding proteins was studied by gel filtration of the graft juices. Intrinsic factor (IF) was looked for in gastric mucosa by immunohistochemistry. The uptake of [57Co]-labeled Cbl by the intestinal graft was studied by Schilling tests and HPLC. IF, haptocorrin, and a transcobalamin-like protein were detected in gastric juice, with concentration ranges of 5.0-26.4, 1.9-27.1, and 5.2-12.6 pmol/mL, respectively. The IF [57Co]Cbl complex had a single isoprotein with a pI at 5.6, which was maintained after incubation with neuraminidase. Urine excretion percentages (Schilling tests) ranged from 5.5 to 21.2% and from 0.3 to 1.6% when cyano-[57Co]Cbl-IF or cyano-[57Co]Cbl, respectively, was instilled in intestinal grafts. Chloroquine reduced significantly the percentage of excreted [57Co]Cbl. The [57Co]Cbl was mainly excreted as cyano-[57Co]Cbl in urines, showing a low coenzyme conversion. In conclusion, IF is secreted by the nonstimulated embryonic stomach and lacks sialic acid. Cbl binds to it and is subsequently transported across the xenografted embryo-fetal intestine. This suggests that amniotic fluid may contribute to Cbl delivery to the embryo-fetus.

Human haptocorrin in hepatocellular carcinoma

This study aimed to determine whether haptocorrin (HC), a vitamin B12 binder, is stored in hepatic cells and whether this storage is modified by hepatic carcinogenesis. It was carried out using immunohistochemistry on different liver tissues (normal liver and steatosis, N = 22; cirrhosis, N = 13; and hepatocellular carcinoma, N = 31). No significant immunostaining of HC was detected in noncancerous biopsies with the exception of in one case of cirrhosis. Hepatocellular carcinoma (HCC) sections showed a weak to moderate cytoplasmic staining of cancerous cells (93% of cases) and of noncancerous hepatocytes surrounding the tumor (95%) of cases. Sections with pseudoglandular structures showed a moderate to strong staining of their secretion products. These results and previous studies would seem to confirm the hypothesis that the raised HC serum level observed in HCC is due both to the increased hepatic synthesis of HC and to a decreased uptake by the liver of the particular isoform of this glycoprotein present in the serum of HCC patients.

Analysis of endotoxin effects on the intact pulmonary circulation

OBJECTIVE

The mechanism of sustained alterations in pulmonary hemodynamics during endotoxin shock remains unclear. To gain more detailed knowledge we used the four-element windkessel model as a descriptor of the pulmonary circuit.

METHODS

Consecutive changes in characteristic resistance (R1), vascular compliance (C), input resistance (R2) and inductance (L) were continuously assessed following injection of endotoxin in 6 anaesthetised pigs, and were compared with the corresponding values measured in a similar group of sham-operated animals.

RESULTS

Endotoxin challenge resulted in a biphasic pulmonary artery pressure response. Blood flow decreased progressively from 2.8 +/- 0.2 l/min to 2 +/- 0.2 l/min. Ohmic pulmonary vascular resistance (PVR) increased gradually from 0.2 +/- 0.04 to 0.76 +/- 0.1 mm Hg s ml-1. The early increase in PAP (from 14 +/- 2 to 27 +/- 4 mm Hg) was mediated by changes in both R1 (from 0.04 +/- 0.01 to 0.06 +/- 0.01 mm Hg s ml-1) and R2 (from 0.16 +/- 0.04 to 0.61 +/- 0.2 mm Hg s ml-1). These responses, in turn, altered the proximal vascular compliance. A subsequent increase in PAP (from 27 +/- 2 to 32 +/- 3 mm Hg) paralleled the specific decline in distal pulmonary vasculature compliance from 0.84 +/- 0.1 to 0.65 +/- 0.1 ml/mmHg. Analysis of the time course of PVR did not allow us to distinguish between vasoconstriction and stiffening of the vascular tree as mechanisms accounting for PAP changes.

CONCLUSIONS

Endotoxemia leads to pulmonary hypertension, which is a result of constriction of proximal pulmonary arteries during the early phase, whereas the late phase is characterised by a decline in distal pulmonary vasculature compliance.