Évaluation de la fonction cardiaque en imagerie par résonance magnétique et scanner hélicoïdal multicoupe

The syndrome of cardiac failure in adults with congenitally corrected transposition

OBJECTIVES

To assess neurohormonal activation of cardiac failure in adults with congenitally corrected transposition, and to determine the most sensitive marker for recognition of the cardiac failure.

BACKGROUND

The onset of morphologically right ventricular dysfunction is unpredictable in patients with congenitally corrected transposition, the combination of discordant atrioventricular and ventriculo-arterial connections, and its markers are unknown.

METHODS

We measured amino terminal pro brain natriuretic peptide in 19 patients, aged 35 plus or minus 13.1 years, and in 19 control subjects. Morhologically right ventricular function was assessed by echocardiography, including tissue Doppler echocardiography and magnetic resonance imaging or multislice computed tomography.

RESULTS

The patients showed a highly significant increase in the levels of amino terminal pro brain natriuretic peptide, the levels being significantly elevated even in asymptomatic patients. Left atrial dimensions were larger in patients, and significantly lower tissue Doppler echocardiographic velocities were measured at the lateral site of the tricuspid annulus and at the basal segment of the interventricular septum. The ejection fraction of the morphologically right ventricle correlated significantly with the levels of brain natriuretic peptide, and with left atrial dimensions.

CONCLUSIONS

Neurohormonal activation is present in patients with congenitally corrected transposition even when they are asymptomatic. It is correlated with left atrial dimensions and tissue Doppler echocardiographic parameters. Levels of brain natriuretic peptide, and peak tricuspid early diastolic annular velocity, are the earliest and most sensitive markers of morphologically right ventricular dysfunction.

Relation of systemic ventricular function quantified by myocardial performance index (Tei) to cardiopulmonary exercise capacity in adults after Mustard procedure for transposition of the great arteries

After Mustard repair for transposition of the great arteries, the right ventricle serves as a chronically overloaded systemic ventricle (SV). Thus, during long-term follow-up, dysfunction of the right ventricle with consecutive heart failure (HF) is not unusual. Early signs and symptoms of HF are depressed parameters of right ventricular (RV) function at rest and exercise intolerance. It was hypothesized that the measurement of RV function parameters, N-terminal pro-brain natriuretic peptide (NT-pro-BNP), and peak oxygen uptake (VO2max) during exercise testing were suitable for the early detection of subclinical HF. In 33 asymptomatic adolescents and adults who had undergone Mustard repair, RV function was analyzed by the myocardial performance index (Tei index). NT-pro-BNP and VO2max were also determined. The corresponding data from 52 patients operated on for left-to-right shunt defects without residual lesions served as reference data. In patients who underwent the Mustard procedure, the Tei index and NT-pro-BNP were elevated (mean Tei index of the SV 0.63 +/- 0.17 vs 0.34 +/- 0.05, p <0.002; mean NT-pro-BNP 240 +/- 230 vs 57 +/- 39 pg/ml, p <0.0001), and VO2max was reduced (27 +/- 6 vs 32 +/- 6 ml x kg(-1) x min(-1), p <0.002). A good correlation was found between the Tei index and VO2max (r = -0.83, p <0.0001). In conclusion, RV function is depressed in most patients with Mustard repair. Ventricular dysfunction in such asymptomatic or minimally symptomatic patients can be detected by measurement of the Tei index, NT-pro-BNP, and VO2max. These parameters are simple and reliable screening methods to stratify patients with impaired cardiac dysfunction before they become symptomatic.