Clinical Investigation
Congenital Heart Disease
The Impact of Preexisting Myocardial Remodeling on Ventricular Function Early after Tetralogy of Fallot Repair

https://doi.org/10.1016/j.echo.2010.06.008Get rights and content

Background

Twenty-three patients (median age 23 months) who underwent Fallot's tetralogy repair were investigated prospectively to detect a possible association between histopathologic myocardial remodeling and echocardiographic findings of systolic or diastolic ventricular dysfunction.

Methods

Intraoperatively resected infundibular bands and subendocardial biopsy samples from the right ventricle (RV) and left ventricle were obtained for histopathologic evaluation. Tissue Doppler echocardiographic interrogation of the ventricles was performed before surgery and in the postoperative period.

Results

Histopathologic data revealed hypertrophy of the RV cardiomyocytes and increased interstitial collagen in both ventricles. Mean values of RV isovolumic acceleration decreased significantly at the third evaluation compared with the preoperative values (P = .006). RV myocardial fibrosis greater than 8.3% was associated with a probability of altered E' of at least 0.7 (odds ratio = 2.31).

Conclusion

Preoperative histologic myocardial remodeling influenced the postoperative RV function in this group of patients with late repair. Further studies are necessary to evaluate the myocardium in younger patients and to define its influence in the long-term follow-up.

Section snippets

Patient Population

We enrolled 23 consecutive patients with tetralogy of Fallot who were electively admitted for corrective surgery at the Heart Institute (InCor), University of São Paulo Medical School, from March 2005 to April 2007. Patient ages ranged from 12 to 186 months (mean = 39.6 months, median = 23 months), and 14 were male (60.9%). Patients with pulmonary atresia or associated atrioventricular septal defect were excluded from the study. Those presenting small atrial septal defects were included.

Before

Clinical and Surgical Features

All corrective surgeries were performed using cardiopulmonary bypass and deep hypothermia. Both the transatrial and transpulmonary approaches were applied in five patients. A transannular patch was used in 10 patients. Six patients had patched widening of the RV outflow tract with no need for a transannular patch. One patient required the insertion of a Dacron conduit between the RV and the pulmonary trunk. The mean bypass time (±SD) was 119.3 ± 37.1 minutes, and the mean aortic crossclamping

Discussion

The postoperative course is usually straightforward in most patients after repair of tetralogy of Fallot. However, it is well known that some patients can experience a prolonged, troublesome postoperative recovery, associated with low cardiac output, increased filling pressures, prolonged ventilation, and inotropic support. Systolic function is usually considered normal in these patients. Abnormalities in RV diastolic function in the immediate postoperative period have been associated with this

Study Limitations

One of the main limitations of our study was that the morphometric data were compared with reference values published previously in the literature, because a control group in this setting would be ethically unacceptable. Another limitation is that all samples were from the subendocardial layer of the myocardium, which could not entirely reflect the remodeling process across the ventricular wall, although it has been demonstrated in necropsy hearts with tetralogy of Fallot that the content of

Conclusions

Myocardial remodeling present preoperatively, as judged by the morphometric histopathologic evaluation of cell hypertrophy and interstitial collagen, has influenced the medium-term postoperative systolic and diastolic RV function, respectively, after tetralogy of Fallot repair. A better understanding of ventricular remodeling and its consequences on ventricular function will provide new insights to deal with an occasionally challenging postoperative course. Further studies are necessary to

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    Supported by Fundação de Amparo à Pesquisa do Estado de São Paulo, grant 05/01476-2.

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