Surgical management of tetralogy of Fallot (TOF) results in anatomic and functional abnormalities in the majority of patients. Although right ventricular volume load due to severe pulmonary regurgitation can be tolerated for many years, there is now evidence that the compensatory mechanisms of the right ventricular myocardium ultimately fail and that if the volume load is not eliminated or reduced by pulmonary valve replacement the dysfunction might be irreversible. Cardiovascular magnetic resonance (CMR) has evolved during the last 2 decades as the reference standard imaging modality to assess the anatomic and functional sequelae in patients with repaired TOF. This article reviews the pathophysiology of chronic right ventricular volume load after TOF repair and the risks and benefits of pulmonary valve replacement. The CMR techniques used to comprehensively evaluate the patient with repaired TOF are reviewed and the role of CMR in supporting clinical decisions regarding pulmonary valve replacement is discussed.

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Repaired tetralogy of Fallot: the roles of cardiovascular magnetic resonance in evaluating pathophysiology and for pulmonary valve replacement decision support

Indications and timing of pulmonary valve replacement after tetralogy of Fallot repair.

Background— Patients after repair of tetralogy of Fallot (ToF) frequently have right ventricular (RV) dysfunction and prolonged QRS duration (QRSd) and thus could be candidates for cardiac resynchronization therapy. We aimed to assess the relationship between QRSd and the timing of RV wall motion, including the RV outflow tract (RVOT), in these patients. Methods and Results— Sixty-seven repaired ToF patients (median age, 34 years; interquartile range, 24 to 43 years) and 35 age-matched control subjects were studied by echocardiography and cardiovascular magnetic resonance (n=55 of 67 ToF patients). Time intervals of the RV cardiac cycle were measured from Doppler recordings. Long-axis M-mode recordings were acquired from the right ventricular (RV) free wall and RV outflow tract (RVOT), and the delay in onset of long-axis shortening was measured. ToF patients showed minor abnormalities of the RV cardiac cycle unrelated to QRSd. RV ejection time was prolonged and correspondingly filling time was reduced com...

Right Ventricular Mechanics and QRS Duration in Patients With Repaired Tetralogy of Fallot. Implications of Infundibular Disease

Background—Recent studies have indicated that there are inherent limitations associated with Fontan physiology. However, there have been no quantitative analyses of the effects of right heart bypass on ventricular afterload, hydraulic power, and resultant overall hemodynamics. Methods and Results—During routine cardiac catheterization, aortic impedance and ventricular hydraulic power were determined, both at rest and under increased ventricular work induced by dobutamine, in 17 patients with Fontan circulation, 15 patients with a single ventricle whose pulmonary circulation was maintained only by Blalock-Taussig shunts, and 13 patients who had normal 2-ventricle circulation. Both vascular resistance (nonpulsatile load on the ventricle) and pulsatile components of ventricular afterload (represented by low-frequency impedance) were significantly higher in the Fontan group than in the other groups (P <0.01), and this was associated with decreased cardiac output in the Fontan patients. In addition, hydraulic power cost per unit forward flow was 40% lower in the 2-ventricle circulation than in the single-ventricle circulation, suggesting lower ventricular efficiency in single-ventricle circulation attributable to the lack of a pulmonary ventricle. Furthermore, in the Fontan group, &bgr;-adrenergic reserve was markedly decreased because of a limited preload reserve. Conclusions—Fontan physiology is associated with disadvantageous ventricular power and afterload profiles and has limited ventricular reserve capacity. Thus, to improve the long-term prognosis of patients after Fontan surgery, future research should be conducted into medical interventions that can overcome these limitations inherent in Fontan circulation.

Ventricular Afterload and Ventricular Work in Fontan Circulation : Comparison with Normal Two-Ventricle Circulation and Single-Ventricle Circulation with Blalock-Taussig Shunts

During the last decade tissue Doppler and myocardial deformation imaging has been introduced to quantify myocardial function in patients with congenital heart disease. These methods could have potential benefits for patients where the anatomy makes it difficult to quantify ventricular function using M-mode or two-dimensional volumetric techniques. In this overview, the potential benefits as well as limitations of the techniques are discussed. Looking directly into the myocardium renders the techniques geometry-independent, allowing the quantification of right ventricular as well as univentricular systolic function. The limitations include the influence of variable loading conditions as well as different methodological problems.

Tissue velocities, strain, and strain rate for echocardiographic assessment of ventricular function in congenital heart disease.

Detection of left ventricular asynchrony in patients with right bundle branch block after repair of tetralogy of Fallot using tissue-Doppler imaging-derived strain

Background
We aimed to assess the existence of myocardial dysfunction and intra-univentricular diastolic asynchrony in patients after Fontan operation.

Moustafa Yigitbasi

Papers

Detection of left ventricular asynchrony in patients with right bundle branch block after repair of tetralogy of Fallot using tissue-Doppler imaging-derived strain

Diastolic asynchrony and myocardial dysfunction in patients with univentricular heart after Fontan operation