Evaluation of preoperative and postoperative cardiac functions with echocardiography and magnetic resonance imaging, in patients undergoing pulmonary valve replacement due to pulmonary regurgitation arising after surgery for fallot tetralogy

Repair with transannular patch extending through the exit of the right ventricle and the pulmonary annulus in tetralogy of Fallot (TOF) leads to pulmonary regurgitation (PR). Severe PVR may cause dilatation and/or dysfunction of the right ventricle (RV) and results in intolerance to physical activity, cardiac failure, arrhythmia and sudden death. As dysfunction of RV is irreversible after a certain degree, it's important to diagnose these patients in the earlier stages and make pulmonary valve replacement (PVR). Absolute indications of replacement are not clear. In our study, we aimed to compare magnetic resonance (MR) imaging which is gold standart for diagnosis, with echocardiographic diagnostic techniques for efficacy in correct timing of PVR and follow-up of patients . Fifteen patients undergoing PVR due to severe PR after surgical treatment of TOF, between 2008 and 2010 in the Başkent University Ankara Hospital were involved in the study. For each patient, enddiastolic and endsystolic volumes and ejection fraction of RV were measured with MR before and 6 months after PVR,. Tissue Doppler (TD) and strain evaluations were made using echocardiography, before, 1, 3 and 6 months after PVR. Eight of the patients were male (%53.3), whilst seven were female (%46.7). Mean age of the patients at the time of prior total correction was 2.3±1.3 years and mean age at the time of PVR was 14.3±4.5 years. 73.3% of the patients had grade 4 PR. 40% of them were asymptomatic. Most common symptom was early exhaustion. There was significant difference between the RVEDV, RVESV, QRS durations measured before and 6 months after PVR (p<0.05). There was no significant difference for RV EF. RVEDV and RVESV values measured by CMR before the PVR were higher than the normal ranges and RV EF was lower. Thus, it was shown that the volume and the size of the RV measured by MR were increased and function was impaired prior to PVR. Using pulse wave TD, it was shown that RV s, e and a velocities were decreased in compliance with systolic and diastolic impairment of RV before the PVR. However satisfactory improvement in myocardial velocities could not be shown after the PVR. The increase in the IVCT and MPI on the 6th postoperative month after PVR was thought to be a proof of ongoing systolic and diastolic dysfunction in the RV otherwise it was the TD method which was not efficient enough to demonstrate recovery of the RV. It was concluded that evaluating the regional myocardial function of the RV with strain imaging was more efficient than evaluating the global functioning of the RV. As S and SR values were below the normal range before PVR, these were considered to be valuable in discriminating the healthy myocardium from the pathological one. There was no significant difference between the S and SR values of symptomatic and asymptomatic patients prior to PVR. It was noted that, early diagnosis of RV dysfunction, before global dysfunction and any symptoms was possible in asymptomatic patients by evaluating regional S and SR. On the 6th month of PVR there was a significant increase in the S and SR values (p<0.05). Strain imaging was found to be more efficient in evaluating the response to treatment when compared to TD. In conclusion, CMR, TD and S were all eligible to demonstrate the dilatation and dysfunction of RV but in contrary to CMR and S, it was not possible to reveal the improvement after PVR with TD. Cardiac MR being the gold standart, increasing experience with strain imaging favors this technique as an easy and non-invasive alternative to CMR.