Guías de práctica clínica de la Sociedad Española de Cardiología en resonancia magnética

Avaliação da função cardíaca por ressonância magnética com seqüências em equilíbrio estável: segmentadas × tempo real

OBJETIVO: Comparar os índices de função sistólica ventricular obtidos entre as seqüências de cine-ressonância magnética em equilíbrio estável, em tempo real e acoplada ao eletrocardiograma, em pacientes com ritmo regular ou não. MATERIAIS E MÉTODOS: Foram comparados a fração de ejeção e os volumes diastólico e sistólico finais, em 31 pacientes, 11 com ritmo cardíaco irregular e 20 com ritmo cardíaco sinusal regular, utilizando-se seqüências segmentadas acopladas ao eletrocardiograma e em tempo real. O tratamento estatístico foi feito através da correlação de Pearson e a concordância de Bland-Altman, com p < 0,01. RESULTADOS: As aquisições em tempo real demonstraram borramento dos contornos endocárdicos, mas ambas as seqüências tiveram forte correlação positiva entre os valores obtidos: fração de ejeção, r = 0,94; volume diastólico final, r = 0,93; volume sistólico final, r = 0,98. A análise dos 11 pacientes com ritmo irregular não demonstrou diferença estatisticamente significativa, apesar da menor relação de contraste sangue-miocárdio. CONCLUSÃO: Seqüências em tempo real podem ser utilizadas para a análise da função cardíaca, independente do ritmo cardíaco dos pacientes.

[Prevalence of patent foramen ovale in young patients with cerebral ischemic accident of unknown origin]

INTRODUCTION AND OBJECTIVE

Patent foramen ovale has been associated with stroke in young patients with cryptogenic stroke. The purpose of this study is to examine the prevalence of patent foramen ovale in this group of patients, as well as their anatomical and functional characteristics by contrast echocardiography, trying to determine ictus risk markers in young patients with acute ischemic stroke.

PATIENTS AND METHOD

Prospective study of 90 patients under the age of 50 who were hospitalised consecutively due to a clinical presentation suggestive of stroke. No cause was found in 55 out of 90 (group I) and the rest, in which an stroke was finally disregarded, were used as the control group (group II). A transthoracic and transesophageal echocardiography examination with 2 types of contrast agents was performed in all patients to determine the presence of a patent foramen ovale and its anatomical and functional characteristics.

RESULTS

Patent foramen ovale was observed more frequently in group I than in group II (43 versus 21%; p < 0.05). Among patients with a patent foramen ovale those with an ischemic stroke showed greater mobility of the oval membrane, more frequent large shunts of contrast in a single frame in the left heart, and more frequent shunts at rest. Transesophageal echocardiography without contrast showed a high sensitivity (90%) and specificity (93%) for detecting anatomically permeable foramen ovale whereas contrast transthoracic echocardiography showed a low sensitivity (13%). There were no differences between the two contrasts used.

CONCLUSIONS

Near half of young patients with ischemic stroke of an unknown origin have a patent foramen ovale. A bigger mobility of the membrane of the oval cavity and a large degree of shunt contrast as well as shunt at rest detected by contrast transesophageal echocardiography, seem to identify patent foramen ovale patients with ischemic stroke. In these patients, transthoracic echocardiography has low sensibility for detecting permeability of the foramen ovale.

[Comparative study of echocardiography and magnetic resonance imaging in the assessment of left ventricular mass]

AIM OF THE STUDY

Echocardiography is a widely applied technique for the estimation of left ventricular mass, although magnetic resonance is considered as a reference method for this purpose. Both techniques were compared in the present study and the usefulness of a simplified method of calculation by magnetic resonance was also tested.

METHODS

Left ventricular mass was determined in 42 patients by M-mode echocardiography by the application of two equations: the so-called Penn's convention and that proposed by the American Society of Echocardiography. Magnetic resonance studies were also performed, left ventricular mass being estimated from an anatomical method (summation of contiguous transverse ventricular slices) that was considered as a reference, and also by means of a geometrical method (planimetry on a single longitudinal view).

RESULTS

Echocardiographic studies were judged as technically inadequate in 3/42 (7%) patients, while magnetic resonance was performed in all cases. Comparison between each echocardiographic method and the anatomical method of magnetic resonance showed a coefficient correlation of r = 0.70 (Penn's convention formula), and r = 0.71 (American Society of Echocardiography), with an overestimation being observed, particularly with Penn's convention method. The geometrical method of magnetic resonance showed an excellent correlation with the anatomical technique (r =0.93).

CONCLUSIONS

Magnetic resonance is more applicable for the estimation of left ventricular mass than M-mode echocardiography, with the latter showing an overestimation when compared with magnetic resonance, particularly with the Penn's convention method. A simplified method of geometrical estimation of left ventricular mass by magnetic resonance is a reliable alternative to the anatomical method.