Biomedical subjects

Ignacio Rodríguez

Publications and source records attributed to Ignacio Rodríguez.

6 recordsLinked to original sources

PubMed2007

Posterior transposition of anterior leaflet for complete chordal preservation.

A method of complete chordal preservation based on posterior transposition of anterior leaflet is presented. The anterior leaflet and chordae are completely detached from the annulus and reimplanted as a large patch under the posterior leaflet. The excess tissue without chordae is excised and the remnant with all the chordae is plicated by sutures used to implant the prosthesis. The posterior leaflet is left intact. The technique is safe and reproducible and no complications related with the procedure have been observed at mid-term follow-up. These results have led to a wider application of total chordal preservation during mitral valve replacement.

Chordae Tendineae↗

PubMed2005

Diffusion-weighted 19F-MRI of lung periphery: Influence of pressure and air-SF6 composition on apparent diffusion coefficients.

Lung functional magnetic resonance imaging (MRI) has become a reality using different inert hyperpolarized gases, such as 3He and 129Xe, which have provided an extraordinary boost in lung imaging and has also attracted interest to other chemically inert gaseous contrast agents. In this context, we have recently demonstrated the first diffusion-weighted images using thermally polarized inhaled sulfur hexafluoride (SF6) in small animals. The aim of this study was to evaluate whether or not the diffusion coefficient of this fluorinated gas is sensitive to pulmonary structure, gas concentration and air pressure in the airways. Diffusion coefficients of SF6 (both pure and in air mixtures) measured in vitro at different pressures and 20 degrees C showed an excellent agreement with theoretical values. Measurements of diffusion coefficients were also performed in vivo and post-mortem on healthy rats, achieving satisfactory signal-to-noise ratios (SNRs), and SF6 gas was found to be in an almost completely restricted diffusion regime in the lung, i.e., the transport by molecular diffusion is delayed by collisions with barriers such as the alveolar septa. This observed low diffusivity means that this gas will be less sensitive to structural changes in the lungs than other magnetic resonance sensitive gas such as 3He, particularly at human scale. However, it is still possible that SF6 plays a role since it opens a new structural window. Thus, the interest of researchers in delimiting the important limiting technical factors that makes this process very challenging is obvious. Among them, T2 relaxation is very fast, so gradient systems with very fast switching rate and probably large radiofrequency (RF) power and high field systems will be needed for hexafluoride to be used in human studies.

Animals↗

PubMed2005

In vivo diffusion weighted 19F MRI using SF6.

Diffusion weighted 19F images of rat lung in vivo using SF6 are presented. Projection-reconstruction images were acquired by filling the rat lung with a mixture of SF6 and air, during 64 successive apneas. Each apnea lasted for 6 s, the time required to perform 100 accumulations of each k-space radial phase step for the five values of the diffusion gradient (TR = 10 ms). After diffusion images were acquired, an apparent diffusion coefficient (ADC) map was generated, yielding an average value for the ADC of 2.22 x 10(-6) m2/s and SD for ADC values of 1.27 x 10(-6) m2/s. To the best of our knowledge, this is the first in vivo diffusion weighting imaging application and the first ADC map obtained using 19F MRI.

Administration, Inhalation↗

PubMed2005

[Trends in coronary artery bypass surgery: changes in the profile of the surgical patient].

INTRODUCTION AND OBJECTIVES: In the last few years, the percentage of high-risk patients proceeding to coronary artery bypass surgery has increased. The most common risk factors are older age and the presence of comorbid complaints. We carried out a retrospective study to confirm this new risk profile and to evaluate its impact on surgical results. PATIENTS AND METHOD: We analyzed the changing risk profile of 1360 patients who underwent coronary artery bypass surgery in our hospital between 1993 and 2001, divided into three historical cohorts: 1993-1996, 1997-1999 and 2000-2001. The main factors associated with morbidity and mortality were analyzed by logistic regression analysis. The introduction of new operative techniques, such as off-pump surgery and arterial grafting, was also evaluated. RESULTS: The patients' risk profile worsened over time: patients were older, comorbid complaints were more common, and ventricular function was poorer. EuroSCORE figures reflected this trend: estimated mortality in the three historical cohorts was 2.0%, 4.0% and 4.2%, respectively (P<.001). However, risk-adjusted mortality, at 3.7%, 2.7% and 1.5%, respectively, decreased (P<.05), and combined overall morbidity and mortality remained stable, at 16.7%, 16.4% and 13.8%, respectively, (P<.39). There was a non-significant tendency for arterial grafting and off-pump surgery to reduce in-hospital morbidity and mortality. CONCLUSIONS: The risk profile of patients undergoing surgery has worsened as their mean age has increased and as comorbid complaints have become more prevalent. However, there has been no simultaneous increase in risk-adjusted mortality. The potential benefits of new surgical advances such as off-pump surgery and multiple arterial grafting must be corroborated by future studies.

Coronary Artery Bypass↗

PubMed2002

Effects of oxygen and glucose deprivation on the expression and distribution of neuronal and inducible nitric oxide synthases and on protein nitration in rat cerebral cortex.

Changes in the nitric oxide (NO) system of the rat cerebral cortex were investigated by immunohistochemistry, immunoblotting, NO synthase (NOS) activity assay, and magnetic resonance imaging (MRI) in an experimental model of global cerebral ischemia and reperfusion. Brains were perfused transcardially with an oxygenated plasma substitute and subjected to 30 minutes of oxygen and glucose deprivation, followed by reperfusion for up to 12 hours with oxygenated medium containing glucose. A sham group was perfused without oxygen or glucose deprivation, and a further group was treated with the NOS inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) before and during perfusion. Global ischemia led to cerebrocortical injury as shown by diffusion MRI. This was accompanied by increasing morphologic changes in the large type I interneurons expressing neuronal NOS (nNOS) and the appearance of nNOS immunoreactivity in small type II neurons. The nNOS-immunoreactive band and calcium-dependent NOS activity showed an initial increase, followed by a fall after 6 hours of reperfusion. Inducible NOS immunoreactivity appeared in neurons, especially pyramidal cells of layers IV-V, after 4 hours of reperfusion, with corresponding changes on immunoblotting and in calcium-independent NOS activity. Immunoreactive protein nitrotyrosine, present in the nuclear area of neurons in nonperfused controls and sham-perfused animals, showed changes in intensity and distribution, appearing in the neuronal processes during the reperfusion period. Prior and concurrent L-NAME administration blocked the changes on diffusion MRI and attenuated the morphologic changes, suggesting that NO and consequent peroxynitrite formation during ischemia-reperfusion contributes to cerebral injury.

Animals↗

PubMedDate not supplied

Surgical ablation of permanent atrial fibrillation by means of maze radiofrequency: mid-term results.

BACKGROUND: The maze procedure can be performed surgically with radiofrequency, generating transmural ablation lines. We report our experience with a biatrial pattern of lesions based on the use of epicardial and endocardial radiofrequency ablation in an effort to minimize maze procedure. METHOD: In 85 patients undergoing cardiac surgery for established permanent atrial fibrillation (>3 months), a biauricular pattern of epicardic-endocardic maze lesions was performed. The main surgical procedures were diverse: 42 mitral valve surgeries, 7 mitrotricuspid valves, 18 mitroaortics, 4 mitroaortic and tricuspids, 2 aortic valves, 3 CABGs, 5 CABG and valve procedures, and 4 atrial septal defects. The mean age of the patients was 61 +/- 12 (range 39-78). The mean duration of atrial fibrillation was 5.8 years (range 0.3 to 24). RESULTS: Sixty-two (72.9%) patients presented postoperative supraventricular arrhythmia. Hospital mortality was seen in five patients (5.8%). Two patients died after a 12-month mean follow-up (range 2 to 32). A total of 14.1% of patients remained with their previous atrial fibrillation and 85.9% recovered and maintained sinus rhythm, with two patients having a permanent pacemaker. A total of 56% patients have been followed-up for a period of more than 6 months, and among them prevalence of sinus rhythm is 87.5%. Echocardiography detected biauricular contraction in 65% of them. After analyzing the data, factors involved in postoperative recurrence of atrial fibrillation after radiofrequency surgery were oldness of the atrial fibrillation (p < 0.01) and pre and postoperative left auricle volume (p < 0.04). CONCLUSION: Intraoperative radiofrequency has permitted us to perform the maze procedure in a simple way, with a low surgical morbid-mortality. We have obtained an 85.9% electrographic effectiveness and a 65% recovery of atrial contraction. Postoperative incidence of arrhythmia is the main postoperative problem.

Adult↗