Biomedical subjects

C Chassat

Publications and source records attributed to C Chassat.

4 recordsLinked to original sources

PubMed1988

Doppler echocardiographic predictors of recurrence of atrial fibrillation after cardioversion.

To determine if the return of atrial contraction as evidenced by progressive return of the A wave on the Doppler atrial profile could better predict long-term success of cardioversion than other clinical and echocardiographic parameters, 50 patients were studied 4 hours, 24 hours and, if sinus rhythm persisted, up to 180 days after cardioversion. Recurrence of atrial fibrillation (AF) was 64% at 6 months. Age, sex, prior episodes of AF, presence of mitral valve disease or magnitude of mitral valve gradient did not predict recurrence, but duration of AF was significantly longer in the failure group (p less than 0.01). Left atrial dimension greater than or equal to 45 mm had a positive predictive value of 66%, with a sensitivity of 59% and a specificity of 61%. Presence or magnitude of the A wave at 4 hours did not predict long-term success of cardioversion. Percent increase of the A wave from 4 to 24 hours less than 10% had the highest positive predictive value (80%) for recurrence of AF (sensitivity 71% and specificity 71%) and can be obtained in the immediate post-cardioversion period to better establish prognosis and adjust therapeutic regimens.

Adult↗

PubMed1988

Assessment of left ventricular function using digital angiography.

We have demonstrated that selective digital left ventricular angiography using small amounts of contrast material minimized both symptoms and hemodynamic alterations and provided good images for assessment of regional ventricular function. However, comparisons of ejection fraction (EF), end-systolic volume (ESV), and end-diastolic volume (EDV) from digital angiography, at 10 frames per second, with measurements derived from conventional angiography, showed only a fair correlation between the two methods. Using a new generation of digital equipment and an acquisition time of 30 frames per second, we studied the correlation between digital and conventional angiography in 29 patients with coronary artery disease for a wide spectrum of left ventricular functions. Ventricular volumes and EF were calculated by computer using the area-length method. The correlation coefficient (r) between both the methods was 0.93 for EF, 0.95 for ESV and 0.89 for EDV. Thus digital left ventricular angiography provides an accurate evaluation of left ventricular function and can with advantage replace conventional angiography for this purpose.

Adult↗

PubMed1986

[Evaluation of new pericardial bioprostheses by pulsed and continuous Doppler ultrasound ].

The authors have studied by pulsed and continuous Doppler ultrasonography 108 pericardial prostheses in a good functional state implanted for less than five years to patients without any clinical and echographic signs of heart failure. The pulsed Doppler ultrasonography allowed to exclude the possible dysfunction of the prostheses; continuous Doppler ultrasonography allowed the measurement of the maximal transprosthetic velocities and to deduce the corresponding maximal and middle gradients by means of simplified Bernouilli's equation. Using three types of bioprostheses (Carpentier-Edwards, Ionescu and Mitroflow) the following problems were investigated: Normal ranges of maximal transprosthetic velocity and gradients. At the aortic level the maximal velocity ranges from 1.60 to 2.83 +/- 14 m/s and the maximal gradients from 10 for size 27-29 to 32 +/- 3.3 mmHg for size 19. At the mitral level the maximal velocity ranges from 0.80 to 2 m/s and the mean gradients from 1 for size 33 to 7 mmHg for size 25. The mean half-life of decrease is 100 +/- 28 ms. Thus all aortic bioprostheses appear to be stenosing, which is not the case for the mitral ones, size 31 and 33. Factors governing the maximal transprosthetic velocity and the gradients: these determining factors are the size, the type and the age of the bioprosthesis (r = 0.59 for the correlation between maximal velocity and size, r = 0.53 between size and mean aortic gradient). The accessory factors are the age and the functional condition of the myocardium. All these factors have to be considered and neutralized for allowing a valid comparison of various types of prostheses. Comparison of the three pericardial prostheses studied: in patients without signs of myocardial dysfunction of prosthetic origin and with comparable basal conditions, comparison of maximal velocity and of the gradient points to a significant superiority of the Mitroflow at the aortic level and of the Ionescu and Mitroflow at the mitral level. It should be noted in the end that the great similarity of the results obtained in the present study by Doppler ultrasonography with the previously reported hemodynamic data confirms the important role of the Doppler method in the evaluation of valvular bioprostheses.

Adult↗

PubMed1986

[Dysfunction of bioprostheses. Respective value of echocardiography and of Doppler studies].

The respective diagnostic values of M mode and 2D echocardiography and pulsed and continuous wave Doppler were assessed in bioprosthetic valve dysfunction. The results of the ultrasonic investigations were compared with the operative findings and anatomo pathological appearances in 56 cases of dysfunction. Only cases with surgical confirmation were included. Doppler examinations were carried out in 13 cases. Echocardiographic imaging alone cannot resolve all the diagnostic problems posed: specific signs are rare and were only observed in one out of 7 cases of periprosthetic leak, 7 out of 10 cases of valvular stenosis and 20 out of 36 cases (55 per cent) of valve tear. In cases of valve tear, 2D echocardiography was falsely normal in 15 per cent of cases and gave equivocal results in 30 per cent of cases because it was not possible to visualise the three cusps of the bioprostheses. Doppler echocardiography does not have the same limitations and gives an immediate and accurate assessment of valve function. It is particularly useful for the diagnosis of stenosis and valve tear in which the diagnostic specificity and sensitivity attain 100 per cent (exact diagnosis in all 11 cases of valve tear). At present, continuous wave Doppler seems to be the most reliable diagnostic tool for qualitative and quantitative assessment of primary degeneration of valvular prostheses.

Adult↗