Noninvasive monitoring of cardiac output in critically ill patients using transesophageal Doppler.

Measurement of cardiac output using thermodilution technique in mechanically ventilated patients is associated with significant morbidity. The goal of the present study was to assess the validity of cardiac output measurement using transesophageal Doppler in critically ill patients. Forty-six patients from three different intensive care units underwent 136 paired cardiac output measurements using thermodilution (COTH) and transesophageal Doppler (COTED). In addition, simultaneous suprasternal Doppler and indirect calorimetry (Fick principle) were used to measure cardiac output in 26 patients from one center. A good correlation was found between COTH and COTED (r = 0.95), with a small systematic underestimation (bias = 0.24 L/min) using transesophageal Doppler. The limits of agreement between COTH and COTED were +2 L/min and -1.5 L/min. Variations in cardiac output between two consecutive measures using either transesophageal Doppler or thermodilution techniques were similar in direction and magnitude (bias = 0 L/min; limits of agreement = +/-1.7 L/min). Suprasternal Doppler and indirect calorimetry yielded similar correlations and agreements in the subset of patients in whom they were used. These results confirm that transesophageal Doppler can provide a noninvasive, clinically useful estimate of cardiac output and detect hemodynamic changes in mechanically ventilated, critically ill patients.

[Color-Doppler study of the velocity profile of the left ventricular outflow tract in normal subjects and in patients with valvular aortic stenosis]. / Etude du profil de vitesse de la chambre de chasse du ventricule gauche des patients normaux et atteints de rétrécissement orificiel aortique. Etude Doppler couleur.

A better understanding of the velocity profiles in the cardiac chambers and great vessels should allow more accurate estimation of cardiac output and valve surface area by Doppler echocardiography. The velocity profile in the left ventricular outflow tract was studied by Colour Doppler in 12 patients with pure valvular aortic stenosis with normal left ventricular function and compared with a control population of 12 normal subjects. The selected recordings were digitised and stocked on a laser optic disc. Measurement of the angle of incidence of the line of colour aliasing with respect to the interventricular septum was performed manually on a colour video display unit. A program of digitised image processing allowed the tracing of the axes of reference defining the angle of incidence measured at peak systole. The average angle of incidence was 40.7 +/- 5.6 degrees in the control population and 56.8 +/- 6.8 degrees in aortic stenosis; therefore, in this condition, the angle was significantly flatter (less acute) (p less than 0.001). The correlation between the angle of incidence and the transvalvular pressure gradient was poor (r = 0.24). These results suggest that: real time ambulatory analysis of isovelocity profiles in the left ventricular outflow tract is possible by using the phenomenon of colour aliasing: the presence of an obstacle to left ventricular ejection tends to flatten the velocity profile, justifying the use of the continuity equation in patients with calcific aortic stenosis but questioning its systematic use in control populations of normal subjects used as a reference.

[Factors influencing survival after surgery of pure non-ischemic mitral insufficiency]. / Facteurs influençant la survie après chirurgie de l'insuffisance mitrale pure non ischémique.

Uni and multifactorial (Cox) statistical analysis of the results of surgery in a series of 247 patients operated between 1969 and 1988 for pure, non-ischaemic mitral regurgitation was undertaken to determine the factors influencing operative and late mortality. All but 3 cases were adults, average age 51 years, and very symptomatic (75 per cent Class III et IV of NYHA Classification). Dystrophic or degenerative lesions were responsible for 53 per cent of cases of regurgitation whilst rheumatic valvular disease was only observed in 30 per cent of cases. Mitral valve replacement was performed in 137 patients (96 mechanical and 41 bioprostheses) and conservative surgery was possible in 110 cases. There were 12 operative deaths (4.9%); the operative risk increased with age and with the practice of valve replacement. Eleven of the 235 survivors (4.7%) were lost to follow-up. During the follow-up period (average 58 months) there were 37 late deaths of which nearly a half were due to left ventricular dysfunction. Multifactorial analysis identified cardiothoracic ratio and atrial fibrillation as predictive factors of late mortality whilst left ventricular ejection fraction and the type of surgery were related to the development of left ventricular dysfunction. The postoperative left ventricular ejection fraction was significantly lower after valve replacement than after valvuloplasty (11 +/- 13% vs 3 +/- 13%; p less than 0.01). These results are therefore in favour of early correction of severe mitral regurgitation by conservative surgery whenever possible.

Fate of pulmonary artery after anatomic correction of simple transposition of great arteries in newborn infants.

From April 1984 to April 1987, surgical anatomic correction was performed in 86 newborn infants, 2-23 days old (6.8 +/- 3.6 days, mean +/- SD) with simple transposition of the great arteries. In all patients, the pulmonary artery was reconstructed by end-to-end anastomosis according to the Lecompte maneuver, including eight patients with side-by-side position of the great arteries. Three different approaches were used. In the first 10 patients (group 1, six survivors), two separate patches of preserved tanned pericardium were used to reconstruct the pulmonary artery, whereas in the next 15 patients (group 2, 13 survivors), a single patch of the same material was used, and in the last 61 patients (group 3, 56 survivors), surgery was performed with a single patch of fresh autologous pericardium. Among the 75 survivors, 68 (including six in group 1, 12 in group 2, and 50 in group 3) were followed serially for at least 6 months (6-48 months, 26 +/- 9 months) with sequential noninvasive evaluations. At follow-up, all were asymptomatic with normal growth. Two patients with severe pulmonary artery stenosis (group 1) were successfully reoperated on. Four infants with moderate pulmonary artery stenosis have been followed medically and have had stable right ventricular pressures. The last 62 patients have normal or near-normal right ventricular pressures. The spatial relation of the great arteries did not affect the quality of the results. Group 1 had clearly the worst results.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional ventricular segmental dynamics in normal conscious dogs.

Left ventricular (LV) subendocardial segmental behavior was analyzed during the whole cardiac cycle for different loading and inotropic conditions in six conscious dogs that were instrumented with ultrasonic crystals in the basal (B) and apical (A) LV regions, a LV micromanometer, and an aortic cuff occluder. There were large variations of A and B segmental behavior during isovolumic contraction and relaxation. In contrast, a linear relationship between A and B was observed during ejection but segmental shortening was larger during control in A than in B, whether it was expressed as a percentage of systolic shortening (34.6 +/- 1.1 and 25.0 +/- 1.2%, respectively; P less than 0.005), or whether segments were normalized for passive resting length. This linear relationship during ejection with a slope of 1.49 was not significantly modified by alterations of loading conditions or inotropic state. The larger A than B shortening, independent of the normalization procedure, is attributed to the regional stress distribution in the LV. The absence of regional and cycle invariance particularly during isovolumic phases prevents the inference of ventricular volume from a limited number of dimensions.

[Myxoma of the right ventricle. Apropos of 2 cases]. / Myxomes du ventricule droit. A propos de 2 observations.

Two cases of primary cardiac tumour are reported. The first was that of a 16 year old girl investigated after the detection of a systolic murmur on routine examination. The clinical signs suggested a diagnosis of pulmonary stenosis. The second case was that of a 36 year old man admitted to hospital for right ventricular failure. Echocardiography revealed right ventricular tumours in both cases and also indicated their size, form, mobility and site of implantation. The outcome of the first case, a fibromyxoma, was favourable with no detectable recurrence after one year. In the second case, the patient unfortunately died of cardiogenic shock in the immediate preoperative period. These two cases emphasise the value of echocardiography in the diagnosis of isolated right ventricular tumours, especially considering the difficulty of clinical diagnosis and the risks of angiocardiography.

End-systolic left ventricular pressure-dimension shift during acute relief of volume overload in the conscious dog.

To test whether left ventricular (LV) end-systolic dimensions are determined only by end-systolic pressure for a given inotropic state, 7 conscious dogs were studied during abrupt closure of a fistula created between the left subclavian artery and the left atrial appendage. The dogs were instrumented with an LV pressure micromanometer and ultrasonic crystals measuring LV major- and minor-axis diameters and ventricular wall thickness. During beta-blockade treatment and for the same end-systolic pressure, closure of the fistula produced a 40% decrease in cardiac output; end-diastolic diameter decreased by 1.5 mm and end-systolic diameter decreased by 0.9 mm. Calculated end-systolic volume was similarly decreased by 1.3 ml for a decrease of 2.9 ml of end-diastolic volume. Thus, large end-diastolic dimensional variations associated with peripheral resistance decrease significantly modify the end-systolic pressure-diameter (and volume) relations in the conscious animal. It is suggested that indexes obtained from these relations should not be used in patients when systolic pressure variations are associated with large stroke volume variations.