Femoral Signal Intensity: A New Method for Prediction of Embolic Risk

Acoustic determination of early stages of intravascular blood coagulation

The blood coagulation system (BCS) is a complex biological system playing a principal role in the maintenance of haemostasis. Insufficient activity of the BCS may lead to bleeding and blood loss (e.g. in the case of haemophilia). On the other hand, excessive activity may cause intravascular blood coagulation, thromboses and embolization. Most of the methods currently used for BCS monitoring suffer from the major disadvantage of being invasive. The purpose of the present work is to demonstrate the feasibility of using ultrasonic methods for non-invasive registration of the early stages of blood coagulation processes in intensive flows. With this purpose, a special experimental set-up was designed, facilitating the simultaneous detection of optical and acoustic signals during the clotting process. It was shown that (i) as microemboli appear in the flow during the early stage of blood coagulation, the intensity of the Doppler signal increases twofold, and (ii) microemboli formation in the early stages of blood clotting always reveals itself through an acoustic contrast. Both of these effects are well defined, so we hope that they may be used for non-invasive BCS monitoring in clinical practice.

Annular systolic velocity predicts the presence of spontaneous echo contrast in mitral stenosis patients with sinus rhythm

OBJECTIVES

Thromboembolism is the major cause of morbidity and mortality in mitral stenosis (MS), even in sinus rhythm (SR). Spontaneous echo contrast (SEC) is the strongest predictor of thromboembolism. The aim of the study was to investigate if the annular velocities obtained with tissue Doppler imaging can predict the presence of SEC in MS patients with SR.

METHODS

One hundred and five MS patients and 100 controls were included. Annular velocities were recorded. All patients underwent transesophageal echocardiography. Subjects were divided into three groups as controls (Group I), the patients without SEC (Group II) and the patients with SEC (Group III).

RESULTS

Group III patients had lower ejection fraction, annular systolic velocity, smaller mitral valve area, higher transmitral gradient and larger left atrial size. The annular systolic velocity was the only independent predictor for SEC. The cutoff values of annular systolic velocity for prediction of the presence of any SEC and dense SEC were 13.5 and 11.8 cm/s, respectively.

CONCLUSION

The annular systolic velocity is an independent predictor for SEC in MS patients with SR.