A Computational Study of the Electrophysiological Substrate in Patients Suffering From Atrial Fibrillation

In the context of cardiac electrophysiology, we propose a novel computational approach to highlight and explain the long-debated mechanisms behind atrial fibrillation (AF) and to reliably numerically predict its induction and sustainment. A key role is played, in this respect, by a new way of setting a parametrization of electrophysiological mathematical models based on conduction velocities; these latter are estimated from high-density mapping data, which provide a detailed characterization of patients' electrophysiological substrate during sinus rhythm. We integrate numerically approximated conduction velocities into a mathematical model consisting of a coupled system of partial and ordinary differential equations, formed by the monodomain equation and the Courtemanche-Ramirez-Nattel model. Our new model parametrization is then adopted to predict the formation and self-sustainment of localized reentries characterizing atrial fibrillation, by numerically simulating the onset of ectopic beats from the pulmonary veins. We investigate the paroxysmal and the persistent form of AF starting from electro-anatomical maps of two patients. The model's response to stimulation shows how substrate characteristics play a key role in inducing and sustaining these arrhythmias. Localized reentries are less frequent and less stable in case of paroxysmal AF, while they tend to anchor themselves in areas affected by severe slow conduction in case of persistent AF.

Hyperbaric oxygen and radiation therapy: a review

About 5% of cancer patients treated with radiotherapy will have severe late-onset toxicity. Hyperbaric oxygen therapy (HBOT) has been used as a treatment for radiation injuries for decades, with many publications presenting data from small series or individual cases. Moreover, we know that the hypoxic areas of tumours are more resistant to radiation. HBOT increases the oxygen tension in tissues and, theoretically, it should enhance the efficiency of radiotherapy. To better understand how HBOT works, we carried out this bibliographic review. We found Grade B and C evidence that at pressures exceeding 2 absolute atmospheres (ata), HBOT reduced late-onset radiation injuries to the head and neck, bone, prostate and bladder. It also appeared to prevent osteoradionecrosis after exodontia in irradiated areas. Finally, HBOT at 2 ata increased the effectiveness of radiation in head and neck tumours and achieved promising results in the local control of high-grade gliomas.

Vitis labrusca leaf extract prevents pentylenetetrazol-induced oxidative damage but not seizures in rats

Epilepsy is a disorder of the central nervous system characterized by recurrent seizures. It is a very common disease in which approximately 30% of patients do not respond favorably to treatment with anticonvulsants. Oxidative stress is associated with neuronal damage arising from epileptic seizures. The present study investigated the possible anticonvulsant and antioxidant effects of a leaf extract of Vitis labrusca in an animal model of seizures induced by pentylenetetrazole (PTZ). The animals received injections of V. labrusca extract (10, 30 and 100 mg/kg) or vehicle and, 30 minutes later, they received an injection of PTZ, and were then observed for 30 minutes. The latency time and tonic—clonic seizure time were registered. Oxidative damage in lipids and proteins was quantified in the cerebellum, cerebral cortex and hippocampus. It was observed that the leaf extract were capable of reducing lipid peroxidation and protein oxidation caused by PTZ at all doses tested.

Mineral content is related to antioxidant and antimutagenic properties of grape juice

Grape juices are an important source of food antioxidants. Unfortunately, there is little data about the mineral composition and the antioxidant, mutagenic and antimutagenic activities of grape juice in eukaryote cells. We evaluated the mineral contents (Mg, Ca, Mn, Fe, Cu, Zn, Si, S, Cl) of grape juices, the antioxidant, mutagenic and/or antimutagenic activities of the juices in the yeast Saccharomyces cerevisiae, and looked for a possible association between mineral content and antioxidant, mutagenic and/or antimutagenic activities of juice samples. Eight commercial grape juices, four purple (Bordo variety) and four white (Niagara variety), were evaluated. Most of the minerals were in similar concentrations in purple and white grape juices, except for calcium and copper; purple grapes had more calcium content and white grapes had more copper content. All grape juices had important antioxidant and antimutagenic activities in S. cerevisiae and prevented the oxidative damage provoked by hydrogen peroxide (P < 0.05). Positive correlations (P < 0.05) were observed between antioxidant and antimutagenic activities and mineral content. In this context, we concluded that the grape juices, white and purple, are an important mineral source, and these contents explain, in part, the important antioxidant and antimutagenic activities.

Effectiveness of Laser treatment at acupuncture sites compared to traditional acupuncture in the treatment of peripheral artery disease

Cardiovascular diseases are the main causes of mortality, not only in Brazil, but around the world. The use of acupuncture as a complementary and alternative treatment for cardiovascular diseases has been suggested for animals as well as human beings. Possible advantages in using acupuncture are the low cost of treatment and low risks of collateral damage from a combination of acupuncture with other medical treatments. The purpose of this study is to assess the effect of traditional acupuncture with needles and laser acupuncture on arterial pressure and peripheral circulation of inferior limbs in patients with circulatory deficiency. Ten acupuncture points were stimulated in 40 individuals, being that 20 were stimulated by Aluminum gallium arsenide (AlGaAs) laser with emission in the red spectral region (650 nm) using an energy density of 2,4 J/cm2, and 20 were stimulated by systemic acupuncture needles. The analysis of peripheral circulation was performed based on the measurement of arterial pressure of the ankle and arms, using sphygmomanometer and Doppler equipment. The variance of the revascularization index of the laser acupuncture group was 0,057, and 0.030 for the needles group with p= 0,006. These results show that only those treated with laser acupuncture exhibit a significant increase in systolic pressure of their lower limbs, with a consequent improvement of the Revascularization Index, suggesting that different stimuli on acupuncture points generate different variations of peripheral resistance of lower limbs. is column.

Three-dimensional holographic imaging of living tissue using a highly sensitive photorefractive polymer device

Photorefractive materials are dynamic holographic storage media that are highly sensitive to coherent light fields and relatively insensitive to a uniform light background. This can be exploited to effectively separate ballistic light from multiply-scattered light when imaging through turbid media. We developed a highly sensitive photorefractive polymer composite and incorporated it into a holographic optical coherence imaging system. This approach combines the advantages of coherence-domain imaging with the benefits of holography to form a high-speed wide-field imaging technique. By using coherence-gated holography, image-bearing ballistic light can be captured in real-time without computed tomography. We analyzed the implications of Fourier-domain and image-domain holography on the field of view and image resolution for a transmission recording geometry, and demonstrate holographic depth-resolved imaging of tumor spheroids with 12 microm axial and 10 microm lateral resolution, achieving a data acquisition speed of 8 x 10(5) voxels/s.

[Familiar chondrocalcinosis: a story for two brothers]

Calcium pyrophosphate dihydrate crystal deposition is frequently an asymptomatic disease. However it may cause severe acute attacks of inflammatory arthritis as well as chronic arthropathies. The authors present two case reports of two brothers with chondrocalcinosis and an unusual presentation that mimics rheumatoid arthritis. Special considerations are made about the differences between the familiar and idiopathic forms.

Phenolic content and antioxidant activities of white and purple juices manufactured with organically- or conventionally-produced grapes

Although the beneficial effects of moderate wine intake are well-known, data on antioxidant capacity of grape juices are scarce and controversial. The purpose of this study was to quantify total polyphenols, anthocyanins, resveratrol, catechin, epicatechin, procyanidins, and ascorbic acid contents in grape juices, and to assess their possible antioxidant activity. Eight Vitis labrusca juices--white or purple, from organically- or conventionally-grown grapes, and obtained in pilot or commercial scale--were used. Organic grape juices showed statistically different (p<0.05) higher values of total polyphenols and resveratrol as compared conventional grape juices. Purple juices presented higher total polyphenol content and in vitro antioxidant activity as compared to white juices, and this activity was positively correlated (r=0.680; p<0.01) with total polyphenol content. These results indicate that white and purple grape juices can be used as antioxidants and nutritional sources.

Transfusion of multiple units of Js(b+) red blood cells in the presence of anti-Jsb in a patient with sickle beta-thalassemia disease and a review of the literature

Jsb is a high-frequency antigen. Anti-Jsb is a rare alloantibody, and its clinical significance is poorly documented. We report a case in which a 12-year-old boy of Nigerian descent with sickle beta- thalassemia presented with multiple alloantibodies, including a panagglutinin and acute chest syndrome, necessitating the emergent transfusion of five units of phenotype-similar, crossmatchincompatible RBCs, four of which were given during an exchange transfusion. The patient was later found to have anti-Jsb. In addition to routine serologic methods to study the patient's RBCs and plasma, a monocyte monolayer assay (MMA) was performed on the patient's samples obtained 2 and 9 days after transfusion of the Js(b+) RBCs to determine the potential clinical significance of the anti-Jsb. Various laboratory parameters including quantitative hemoglobin fraction analyses were used to monitor for increased RBC destruction. The MMA reactivity of the patient's anti-Jsb increased from 2.3 percent on day 2 after transfusion to strongly positive at 88 percent and 66.5 percent (with and without the addition of fresh serum) 1 week later. MMA reactivity of greater than 5 percent is associated with increased RBC destruction. There was no clinical or laboratory evidence of increased hemolysis above baseline. However, decreased RBC survival was suggested by the relatively brisk decrease of the HbA1 fraction after the transfusions. The current case and others reported in the literature suggest that anti-Jsb may have limited potential for causing overt hemolysis. However, in patients with underlying hematologic disease, even mildly increased RBC destruction may pose problems clinically,and thus transfusion of Js(b+) RBCs should be avoided. In emergent situations, the potential of adverse effects of transfusing incompatible units should be balanced against the risk of withholding transfusion. Family members, especially siblings, should be considered as potential designated donors for patients with antibodies directed against high-frequency antigens. Available reports on anti-Jsb in the literature are also reviewed.

An outbreak of Legionnaires' disease in an inner city district: importance of the first 24 hours in the investigation

OBJECTIVE

To present the main results of the investigation of an outbreak of Legionnaire's disease that occurred in an inner city district of Barcelona between 15 October and 15 November 2000.

METHODS

Epidemiological surveys of patients and environmental investigations were initiated on the day the first five cases were notified. Water samples and smears from cooling tower trays were taken for microbiological analysis. Maps of the distribution of cases and possible contamination foci were elaborated. Incidences were calculated for each census tract.

RESULTS

A total of 54 patients related to the outbreak were identified, with a case fatality rate of 5.5%. Incidence rate in the area closest to the cooling tower (6.40/1000) was significantly higher than that of the rest of the neighbourhood (2.23/1.000, RR 2.87, 95%CI 1.37-6.12, P = 0.0035). Cultures positive for Legionella pneumophila serogroup 1, subtypes Pontiac, Philadelphia or Allentown, were obtained from eight patients. On the 39th day of the investigation it was found that the strain isolated in one of the cooling towers coincided with the serogroup, subtype and molecular profiles identified in clinical samples.

CONCLUSIONS

Rapid coordination of clinicians, microbiologists, epidemiologists and environmentalists permitted the source of infection and the affected cases to be correlated within a few days.

[Long-term development of blood pressure profile in hypertensive hemodialysis patients]

OBJECTIVE

The prognostic value of nocturnal blood pressure (BP) in hemodialysis patients has been well established. The aim of this study was to evaluate the long-term outcome of ambulatory BP in hypertensive hemodialysis patients.

DESIGN AND METHODS

Medical records of all hemodialysis patients seen for uncontrolled hypertension between 1993 and 1999 and who underwent an ambulatory blood pressure measurements (ABPM) were retrospectively studied. Uncontrolled hypertension was defined as office BP = 140/90 mmHg and 24 h ABP = 125/80 mmHg. Patients who underwent a second ABPM after an interval of at least 1 year were included in the study. Demographic characteristics, medical history, cardiovascular risk factors and treatments were recorded for each patient. A t-test (bilateral) was used to compare BP.

RESULTS

26 patients were included (545 +/- 18.9 years; 14 men). 7 had previous history of cardiovascular disease and 2 were diabetic. At the end of the follow-up (29 +/- 12.8 months), 9 patients (36%) had 24 h BP < 125/80 mmHg. A significant decrease in diurnal and nocturnal BP was observed (p < 0.05). No significant change was observed for office systolic BP and predialytic BP.

CONCLUSION

Our data show that a long-term decrease in nocturnal BP can be obtained in hypertensive patients on hemodialysis. With respect to the prognostic value of this criteria, randomised trials could be carried out to determine whether nocturnal BP is superior to office BP as a target for antihypertensive therapy in this population.

Prevention of stress-induced hypertension in hypertensive patients

The aim of the study was to assess the course of the alerting reaction during an effective antihypertensive treatment, and to discuss its interference with the conduct of therapy. In 28 patients suffering from mild to moderate hypertension, the basal blood pressure was measured in an outpatient clinic according to a standardized procedure, first by a nurse, then by a 12-min recorded monitoring, and then by a physician using a mercury sphygmomanometer with the patient in the upright and then the supine position. In comparison with the monitoring (mean values recorded at 6, 9, and 12 min), there was a significant increase in diastolic and systolic blood pressure taken by the nurse and by the physician, which diminished at the end of the visit with the physician. Patients then received 10 mg of bisoprolol each morning and presented again on day 30 and day 60, following the same procedure and under identical conditions. Despite the desired antihypertensive effect, the alerting reaction persisted at each visit up to the end of the study, being unchanged in the case of the systolic blood pressure and accentuated in the case of the diastolic blood pressure. Our results confirm those of previous investigations showing that even an effective antihypertensive therapy is unequivocally associated with a persisting alerting reaction irrespective of the antihypertensive drug applied. Thus, patients may be exposed to the potential risk involved with false failures and unnecessary overtreatment. The physician must compare his or her own measurements with readings made outside the consulting office and must program ambulatory blood pressure monitoring in the case of discrepancy. This is a suitable means of confirming and validating blood pressure measurements, as this method does not record the alerting reaction.

[Microalbuminuria, pulse wave velocity and common carotid artery intima-media thickness in type 2 diabetes]

The aim of the study was to evaluate pulse wave velocity (PWV) and carotid intima-media thickness (IMT) in type 2 diabetics with microalbuminuria (mualb). The study concerned 37 patients type 2 diabetics, age: 53.4 +/- 6.6, years free of cardiovascular complications. HbA1C was 7.73 +/- 1.39%, waist circumference 104.2 +/- 11.7 cm. 19 patients with BP > 130/85 mmHg were identified as mild hypertensives (17/19 under treatment). All patients underwent ABPM, PWV and IMT measurements. The study population was separated into 2 subgroups according to median of mualb (mg/24 h): 18.9. [table: see text] In patients with mualb > 18.9 mg/24, IMT and PWV were significantly increased (p = 0.06; p < 0.01). After adjustment to BP and age, there was no significant difference in IMT and PWV in the subgroups. In this selected population of type 2 diabetics, microalbuminuria appears associated to a pressure-dependant vascular remodeling.

[Prophylactic value of automatic implantable defibrillators: a case report of a patient with asymptomatic Brugada syndrome]

The authors report the case of an asymptomatic 32 year old man with no family history of sudden death but with ECG changes suggesting Brugada's syndrome. He underwent implantation of an automatic defibrillator after inducible syncope ventricular fibrillation had been demonstrated during electrophysiological investigation. The later occurrence of three episodes of ventricular fibrillation treated by the defibrillator confirmed a posteriori the logic of this therapeutic approach.

[Acute blood pressure elevations]

Blood pressure (BP) elevations may correspond to different clinical situations. Hypertensives emergencies are situations that require immediate reduction in BP because of acute or rapidly progressing target organ damage: accelerated malignant hypertension, hypertensive encephalopathy, acute myocardial infarction, acute aortic dissection, acute left ventricular failure, and eclampsia. Hypertensive urgencies are those with marked elevated BP in which it is desirable to reduce BP progressively within few hours, such as severe hypertension, progressive target organ damage, perioperative hypertension. Cerebrovascular accidents have to be individualized. In most patients in the immediate post-stroke period, BP should not be lowered. Caution is advised in lowering BP in these patients because excessive falls may precipitate cerebral ischemia. In situations without symptoms or progressive target organ it is necessary to exclude proximate causes of elevated BP such as pain and elevated BP alone rarely requires antihypertensive treatment. Among parenteral antihypertensive (AH) drugs labetalol, nicardipine, urapidil, and nitroprussiate are generally used, and the choice of AH drug depends on the clinical situation. It is not required to normalize BP immediately but to reduce mean BP no more than 25%, then toward 160/100 mmHg as recommended by JNC VI, in order to avoid an impairment of renal, cerebral or coronary ischemia. Oral long-acting dihydropyridines are often subsequently administrated, except in myocardial ischemia. Therapeutic attitudes vary considerably according to the clinical situation: abstention, immediate decrease or progressive decrease in BP have to be decided.

Solitary fibrous tumour of the orbit. Report of a new case

PURPOSE

Solitary fibrous tumour (SFT) of the orbit is a very rare lesion that may be misdiagnosed as fibrous histiocytoma, haemangiopericytoma, or other orbital tumour. We studied a case of SFT of the orbit in a 35-year-old woman.

METHODS

The patient, with a 1-year history, reported a 'pressure' sensation behind her right eye, but no pain, vision changes, or other associated symptoms. Ocular examination was normal. Magnetic resonance imaging (MRI) showed a well-circumscribed medial mass in the right orbit. The tumour was excised.

RESULTS

The tumour was a cellular spindle-cell neoplasm with a storiform pattern. The tumour cells were spindle-shaped with bland nuclei and rare mitoses. Immunostaining was positive for vimentin and CD34, but negative for cytokeratin (AE1-AE3), EMA, desmin, smooth muscle actin, S-100, CD31, CD45 and bcl-2.

CONCLUSION

SFT can infrequently involve the orbit. The tumour must be removed entirely to avoid recurrences. Careful and continued follow-up is important because orbital recurrence may occur several years after the excision of the primary tumour.

Nocturnal blood pressure and 24-hour pulse pressure are potent indicators of mortality in hemodialysis patients

BACKGROUND

Cardiovascular (CV) complications are the leading cause of mortality in hemodialysis patients. The role of arterial hypertension on the prognosis of CV in hemodialysis patients is not as clear as in the general population. The purpose of this study was to investigate the prognostic role of ambulatory blood pressure (BP) on CV mortality in treated hypertensive hemodialysis patients.

METHODS

Fifty-seven treated hypertensive hemodialysis patients (56.87 +/- 16.22 years, 30 men) were prospectively studied. All patients initially underwent an ambulatory BP monitoring between two dialysis sessions. The outcome event studied was CV death; kidney transplantation and deaths not related to CV disease were censored.

RESULTS

The duration of follow-up was 34.4 +/- 20.39 months, during which 10 CV and 8 non-CV fatal events occurred. In the 10 patients who died from CV complications, age, previous CV events, ambulatory systolic BP, ambulatory pulse pressure (PP), and life-long smoking level were significantly higher, and the office diastolic BP was lower at the time of inclusion than in those who did not die from CV complications (N = 47). Based on Cox analysis and after adjustment for age, sex, and previous CV events, a low office diastolic BP [relative risk (RR) 0.49, 95% CI, 0.25 to 0.93, P = 0.03], an elevated 24-hour PP (RR 1.85, 95% CI, 1.28 to 2.65, P = 0.009), and an elevated nocturnal systolic BP (RR 1.41, 95% CI, 1.08 to 1.84, P = 0.01) were predictors of CV mortality (RR associated with a 10 mm Hg increase in BP and in PP).

CONCLUSION

This study demonstrates that nocturnal BP and 24-hour PP are independent predictors of CV mortality in treated hypertensive hemodialysis patients. Randomized trials are needed to investigate whether nocturnal BP and 24-hour PP are superior to office BP as targets for antihypertensive therapy in this high-risk group.

[Treatment of arterial hypertension in the diabetic]

BLOOD PRESSURE CONTROL: More than half of all diabetic patients have high blood pressure. Even more so than in the general population, hypertension compromises the cardiovascular and renal prognosis. Optimal blood pressure control can limit the progression of microangiopathy and macroangiopathy as clearly demonstrated in the HOT and UKPDS studies. For the WHO, the goal is to control pressures < 130/85 mmHg. In this respect, there has been no demonstration of a J-curve relationship between pressure lowering with antihypertension drugs and incidence of cardiovascular events among patients with coronary artery disease included in the HOT study.

MULTIPLE DRUG THERAPY

Regular long-term monitoring and, in most cases, multiple-drug regimens, are prerequisites for maintaining pressure figures below 130/85. When elaborating a blood pressure control protocol, it is important to consider the presence of coronary artery disease, suggesting use of beta blockers, or renal disease, which should lead to the use of angiotensin converting enzyme inhibitors. Diuretics play an important role in combination regimens and are indispensable in three-drug protocols or in case of altered renal function.

SYSTOLIC HYPERTENSION

Subgroup analyses in the SHEP and SYST-EUR studies demonstrated the importance of treating pure systolic hypertension in diabetics. The protection obtained has the same or even more impact than in the general population.

RISK FACTORS

Diabetes control must of course be maintained and coherent management requires taking into consideration all the risk factors, especially smoking and dylipidemia.

[Influence of absolute risk and sex on the treatment of arterial hypertension in Haute-Garonne]

OBJECTIVE

WHO management plan for mild hypertension recommends to take into account total cardiovascular risk in the decision treatment making process. However, despite a lower coronary risk in women than in men, hypertension awareness, treatment and control were higher in women than in men. This study was designed to evaluate the relationships between sex, coronary risk, awareness and treatment of hypertension in Haute-Garonne a south western French region.

METHODS

1,160 subjects aged 35-64, 600 men, were recruited between 1994 and 1996 by the Toulouse MONICA center. Subjects were selected by stratified randomization on age and size of home area. For each patient a score of coronary risk based on Framingham equation was calculated.

RESULTS

157 treated hypertensives (HT), 73 men and 84 women (G1) whom 046 adequately treated were identified, 16 men and 30 women. 60 known but untreated HT, 38 men and 22 women (G2), 171 newly diagnosed HT, 115 men and 53 women (G3). In men, the coronary risk score was higher in treated hypertensives compared with G2 and G3 (G1: 19.19 +/- 5.77 vs G2: 16.71 +/- 6.12 vs G3: 17.42 +/- 5.65) while no significant difference was observed in BP between these three groups (G1: 150.73 +/- 18.6/88.57 +/- 10.81 vs G2: 151.97 +/- 10.59/89.73 +/- 8.04 vs G3: 146.68 +/- 12.14/90.05 +/- 9.19) were observed between these three groups. In treated men, patients were older, total cholesterol was lower, intake of hypolipidemic drugs and diabetes were more prevalent than in the other two groups. In women, coronary risk score were not significantly different between the three groups.

CONCLUSION

This study confirms the higher rate of awareness, treatment and control of hypertension in women. In men, treated hypertensives are at higher coronary risk than untreated and/or unawareness hypertensives: an improvement of hypertension control appears the prerequisite to decrease absolute cardiovascular risk in this group. In women, treated patients have a risk close to the level observed in untreated hypertensives.