372 research outputs found
Minimally Invasive Mapping Guided Surgical Treatment of Atrial Fibrillation. Utopia or Near Future?
Isolation of the pulmonary veins has been used as surgical treatment for atrial fibrillation (AF) from the early 90s, as it was incorporated in the Maze procedure. With the evidence that triggers form this area can induce AF, the Maze III procedure has been adapted and modified towards a single lesion around the pulmonary veins for the treatment of paroxysmal and chronic AF in some centers. New ablation techniques with a diversity of energy sources further paved the way for less invasive procedures. Minimal invasive techniques to prevent major surgery may potentially make the treatment available for a patient population that do not have to undergo cardiac surgery for other reasons. Besides these technical developments, high density mapping can be used to identify the AF substrate in the individual patient and optimization of the treatment by local substrate guided ablation. This review aims to summarize the robotic and thoracoscopic techniques to isolate the pulmonary veins. Furthermore, it is discussed why pulmonary veins isolation may be effective in patients with chronic AF, and whether there is a role for mapping guided minimal invasive surgical treatment of AF in the near future
The nonmesonic weak decay of the hypertriton
The nonmesonic decay of the hypertriton is calculated based on a hypertriton
wavefunction and 3N scattering states, which are rigorous solutions of 3-body
Faddeev equations using realistic NN and hyperon-nucleon interactions. The
pion-exchange together with heavier meson exchanges for the transition is considered. The total nonmesonic decay rate is found to be 0.5%
of the free decay rate. Integrated as well as differential decay
rates are given. The p- and n- induced decays are discussed thoroughly and it
is shown that the corresponding total rates cannot be measured individually.Comment: 27 pages, 20 figures, revtex, submitted to Phys. Rev.
Surgery versus stereotactic radiotherapy for treatment of pulmonary metastases. A systematic review of literature
It is not clear as to which is the best treatment among surgery and stereotactic radiotherapy (SBRT) for lung oligometastases. A systematic review of literature with a priori selection criteria was conducted on articles on the treatment of pulmonary metastases with surgery or SBRT. Only original articles with a population of patients of more than 50 were selected. After final selection, 61 articles on surgical treatment and 18 on SBRT were included. No difference was encountered in short-term survival between pulmonary metastasectomy and SBRT. In the long-term surgery seems to guarantee better survival rates. Mortality and morbidity after treatment are 0-4.7% and 0-23% for surgery, and 0-2% and 4-31% for SBRT. Surgical metastasectomy remains the treatment of choice for pulmonary oligometastases. Patients with metastatic cancer with a limited number of deposits may benefit from surgical removal or irradiation of tumor nodules in addiction to chemotherapy. Surgical resection has been demonstrated to improve survival and, in some cases, can be curative. Stereotactic radiotherapy is emerging as a less invasive alternative to surgery, but settings and implications of the two treatments are profoundly different. The two techniques show similar results in the short-term, with lower complications rates for radiotherapy, while in the long-term surgery seems to guarantee higher survival rates
Bioengineering of Improved Biomaterials Coatings for Extracorporeal Circulation Requires Extended Observation of Blood-Biomaterial Interaction under Flow
Extended use of cardiopulmonary bypass (CPB) systems is often
hampered by thrombus formation and infection. Part of these
problems relates to imperfect hemocompatibility of the CPB
circuitry. The engineering of biomaterial surfaces with genuine
long-term hemocompatibility is essentially virgin territory in
biomaterials science. For example, most experiments with the
well-known Chandler loop model, for evaluation of
blood-biomaterial interactions under flow, have been described for
a maximum duration of 2 hours only. This study reports a systematic
evaluation of two commercial CPB tubings, each with a
hemocompatible coating, and one uncoated control. The experiments
comprised (i) testing over 5 hours under flow, with human whole
blood from 4 different donors; (ii) measurement of essential blood
parameters of hemocompatibility; (iii) analysis of the luminal
surfaces by scanning electron microscopy and thrombin generation
time measurements. The dataset indicated differences in
hemocompatibility of the tubings. Furthermore, it appeared that
discrimination between biomaterial coatings can be made only after
several hours of blood-biomaterial contact. Platelet counting,
myeloperoxidase quantification, and scanning electron microscopy
proved to be the most useful methods. These findings are believed
to be relevant with respect to the bioengineering of
extracorporeal devices that should function in contact with blood
for extended time
Pion-Lambda-Sigma Coupling Extracted from Hyperonic Atoms
The latest measurements of the atomic level width in Sigma-hyperonic Pb atom
offer the most accurate datum in the region of low-energy Sigma-hyperon
physics. Atomic widths are due to the conversion of Sigma-nucleon into
Lambda-nucleon. In high angular momentum states this conversion is dominated by
the one-pion exchange. A joint analysis of the data of the scattering of
negative-Sigma on proton converting into a Lambda and a neutron and of the
atomic widths allows to extract a pseudovector pion-hyperon-Sigma coupling
constant of 0.048 with a statistical error of +-0.005 and a systematic one of
+-0.004. This corresponds to a pseudoscalar coupling constant of 13.3 with a
statistical uncertainty of 1.4 and a systematic one of 1.1.Comment: 12 pages, 1 figure, Use of Revtex.st
The weak strangeness production reaction in a one-boson-exchange model
The weak production of Lambdas in nucleon-nucleon scattering is studied in a
meson-exchange framework. The weak transition operator for the reaction is identical to a previously developed weak
strangeness-changing transition potential that describes the
nonmesonic decay of hypernuclei. The initial and final state
interaction has been included by using realistic baryon-baryon forces that
describe the available elastic scattering data. The total and differential
cross sections as well as the parity-violating asymmetry are studied for the
reaction . These observables are found to be sensitive to the
choice of the strong interaction potential and the structure of the weak
transition potential.Comment: 25 pages, 8 postscript figures. Submitted to Phys. Rev.
Surgical repair of post-infarction ventricular free-wall rupture in the Netherlands: data from a nationwide registry
Background: Ventricular free-wall rupture (VFWR) is an infrequent but catastrophic complication of acute myocardial infarction (AMI). Most reports about outcome after surgical treatment are single-center experiences. We examined the early and mid-term outcomes after surgical repair of post-AMI VFWR using the Netherlands Heart Registration (NHR) database. Methods: We included data from NHR patients (>18 years old) who underwent surgery for post-AMI VFWR between 2014 and 2019. The primary end-point was in-hospital mortality. Secondary outcomes included postoperative complications and mid-term survival. Results: The study included 148 patients (54.7% male, mean age 66.5±11.1 years). Critical preoperative status was found in 62.6% of subjects. In-hospital mortality was 31.1% (46 of 148). Multivariable analysis identified female sex [odds ratio (OR), 5.49; 95% confidence interval (CI): 2.24–13.46] and critical preoperative status (OR, 4.06; 95% CI: 1.36–12.13) as independent predictors of in-hospital mortality. The overall median postoperative follow-up was 2.2 (interquartile range, 0.7–3.8) years. Overall survival rates at three and five years were 58.9% and 55.7%, respectively. Among hospital survivors, only 15 (14.7%) patients died during follow-up, with a five-year survival rate of 80.8%. Conclusions: In-hospital mortality after surgical repair of post-AMI VFWR is considerable. Female sex and preoperative critical status are independent predictors of early postoperative (in-hospital) death. Logistic EuroSCORE I can reliably predict in-hospital mortality (optimal cut-off >33%). Mid-term follow-up of patients surviving in-hospital course shows excellent results
Hyperon-nucleon scattering and hyperon masses in the nuclear medium
We analyze low-energy hyperon-nucleon scattering using an effective field
theory in next-to-leading order. By fitting experimental cross sections for
laboratory hyperon momenta below 200 MeV/c and using information from the
hypertriton we determine twelve contact-interaction coefficients. Based on
these we discuss the low-density expansion of hyperon mass shifts in the
nuclear medium.Comment: 10 pages, 2 figure
A ventricular-vascular coupling model in presence of aortic stenosis
In patients with aortic stenosis, the left ventricular afterload is determined by the degree of valvular obstruction and the systemic arterial system. We developed an explicit mathematical model formulated with a limited number of independent parameters that describes the interaction among the left ventricle, an aortic stenosis, and the arterial system. This ventricular-valvular-vascular (V(3)) model consists of the combination of the time-varying elastance model for the left ventricle, the instantaneous transvalvular pressure-flow relationship for the aortic valve, and the three-element windkessel representation of the vascular system. The objective of this study was to validate the V(3) model by using pressure-volume loop data obtained in six patients with severe aortic stenosis before and after aortic valve replacement. There was very good agreement between the estimated and the measured left ventricular and aortic pressure waveforms. The total relative error between estimated and measured pressures was on average (standard deviation) 7.5% (SD 2.3) and the equation of the corresponding regression line was y = 0.99x - 2.36 with a coefficient of determination r(2) = 0.98. There was also very good agreement between estimated and measured stroke volumes (y = 1.03x + 2.2, r(2) = 0.96, SEE = 2.8 ml). Hence, this mathematical V(3) model can be used to describe the hemodynamic interaction among the left ventricle, the aortic valve, and the systemic arterial system
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