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Biomedical subjects

J Cortina

Publications and source records attributed to J Cortina.

24 records · Page 2Linked to original sources
PubMed1993

Effect of site, summation and asynchronism of inputs on atrioventricular nodal conduction and refractoriness.

The impulses coming from the sinus node synchronically penetrate the AV node via the crista terminalis and inter-atrial septum. Studies in superfused rabbit AV preparations suggest that the crista terminalis is a more effective input than the inter-atrial septum, and that the summation of both inputs facilitates AV nodal conduction. The aim of this study was to verify the hypothesis in a more physiological model, such as the whole rabbit heart perfused by a Langendorff system. Fifteen rabbit hearts were studied in a Langendorff perfusion system with six bipolar extracellular electrodes: two for stimulating (crista terminalis and inter-atrial septum) and four for recording (crista terminalis, inter-atrial septum, His bundle electrogram and right ventricle). Seven hearts (Group I) were consecutively paced at the crista terminalis, inter-atrial septum and both sites simultaneously, to determine the AV nodal Wenckebach cycle length and effective refractory period under basal conditions and after acetylcholine (0.75 x 10(-6) M). In eight hearts under 0.75 x 10(-6) M acetylcholine (Group II), the crista terminalis and inter-atrial septum were simultaneously (delay = 0 ms) or sequentially (delay = 2, 4, 6, 8, 10, 12, 14, and 16 ms) stimulated to calculate the AV nodal effective refractory period and the AH interval at an atrial coupling interval 5 ms longer than the AV nodal effective refractory period, for each delay tested.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

[The protection of an internal mammary artery graft with a tubular prosthesis made of polytetrafluoroethylene].

A polytetrafluoroethylene tubular prosthesis was used to protect an internal mammary artery graft in a patient with high risk of reoperation. This technique was used to avoid the risk of damage of the graft and to reduce the difficulties of the injection of cardioplegia during the reoperation procedure. The usefulness of this technique is discussed in the article.

Angina, Unstable↗
PubMed1993

[Left ventricular outflow obstruction due to accessory mitral tissue].

An asymptomatic 31-year-old woman was studied because she presented a systolic ejection cardiac murmur. The echocardiogram showed a mobile, sac-like mass attached to the ventricular surface of the anterior mitral leaflet and its chordae tendineae and papillary muscle. This structure moved to the left ventricular outflow tract during every systole occupying the subaortic area. Conventional and color-coded Doppler examination revealed left ventricular outflow obstruction caused by the accessory mitral valve tissue that produced a high-velocity turbulent flow pattern in the subaortic area where the sac-like structure approximated to the outflow tract walls.

Adult↗
PubMed1987

Reoperations for left-sided low-profile mechanical prosthetic obstructions.

A series of 2,474 hospital survivors of primary mitral, aortic, and double mitral-aortic valve replacement were observed for a cumulative period of 11.945 years (mean, 4.2 years; range, 0.6-14 years). The linearized incidences of reoperations for thrombotic obstructions were 0.33 +/- 0.08% for mitral valve replacement, 0.36 +/- 0.1% for aortic valve replacement, and 0.42 +/- 0.1% for double valve replacement (p = not significant). Forty-one patients (16 mitral, 12 aortic, and 13 double valve replacements) underwent a total of 44 reoperations with a mean interval of 36 +/- 29 months (range, 0.25-85 months) between operations. Diagnosis was established invasively only in 13 patients (30%). Hospital mortality at reoperation was 18% (8 patients); 28 patients (63%) required emergency surgery. The choice surgical procedures were thrombectomy for clotted aortic prostheses (18 of 24) and valve replacement for obstructed mitral valves (22 of 25; p less than .001). Rethrombosis occurred in 3 patients (1 aortic and 2 double valve replacements). At hospital admission 17 patients (38%) had prothrombin times outside therapeutic ranges (between 20 to 30% of the normal value). The incidence of reoperations for thrombosis in low-profile mechanical prostheses was unaffected by valvar position and number of prostheses implanted. Rethrombosis occurred only in previously cleaned valves, although its occurrence was not significant. The present results indicate that, as experience is gained in the diagnosis and surgical management of this complication, hospital mortality can be reduced significantly (from 37% to 4%).

Aortic Valve↗