Prof. Owen Miller
Multimodality assessment of size, shape, deformation and function is key to understanding Interventricular interactions in Congenital Heart Disease.
The joint session between the EACVI and ASE explored interventricular interactions across a wide range of Congenital Heart Disease (CHD) lesions, where disease in the right ventricle (RV) has a major impact on left ventricular (LV) function.Dr Annemien van den Bosch (Rotterdam) spoke about the impact of Tetralogy of Fallot on LV function. Repaired tetralogy in the adult will often be complicated by free pulmonary regurgitation resulting in RV dilatation and RV dysfunction; there is often concomitant RV hypertrophy, Tricuspid Regurgitation (TR) and right atrial dilatation. Apart from heart failure, the feared consequence is sudden cardiac death (SCD). Associated LV dysfunction has been shown to be an independent risk factor for SCD with LV longitudinal dysfunction being associated with greater risk (1-2). The close relationship between reduced RV ejection fraction (EF) and reduced LV EF was shown on papers from Yoo (3), and Geva (4). There is both systolic and diastolic LV dysfunction predominantly associated with abnormal septal position and a change in LV shape. Dr van den Bosch expanded on the fundamental anatomy of the fibre orientation around the RV, LV and both ventricles, where the common circumferential fibres exert a traction effect on the LV when RV dilatation present. Deformation imaging showed characteristic changes on the circumferential twist of the LV in patients with repaired tetralogy.The second paper from Dr Mark Friedberg (Toronto) looked at the effect of Pulmonary Hypertension (PHT) on RV-LV crosstalk. Experimental studies have previously shown the importance of LV contraction on RV pressure development(5) and the role of pericardial constraint on RV function (6). PHT also has a marked effect on septal position and consequent LV function, shown both with echocardiography and Cardiac Magnetic Resonance (CMR)(7). Assessment of circumferential strain in PHT shows that RV contraction is prolonged compared with LV contraction exacerbating the abnormal septal position (8) and limiting the duration of diastole and increasing the Systolic to Diastolic (S:D) ratio. Increased S:D ratio was a major risk factor for adverse outcome (9). Novel surgical approaches using aortic constriction lead to an increase in RV stroke volume in experimental PHT (10). PHT associated RV fibrosis is being investigated with potential new therapeutic strategies using carvedilol.Dr Leo Lopez (Miami) spoke on Ebstein’s anomaly and its effect on RV-LV cross talk. The important RA reservoir function can be severely affected in Ebstein, leading to changes in RV filling and RV output. In addition to the hemodynamic effects of “atrialisation”, there is intrinsic LV dysfunction due to increased fibrosis shown by late enhancement on CMR and LV non compaction seen in up to 25% of cases (11). The final piece of the jigsaw puzzle was provided by Dr Beatrice Bonello (Marseille) who looked at the systemic RV in congenitally corrected Transposition of the Great Arteries (ccTGA). Long term natural history of ccTGA is poor in many, but surgical options are complex. In preparation for surgical correction (Double Switch operation), the LV needs to be “trained” often involving a pulmonary artery band to increase LV afterload. Despite this staged approach, outcome remains guarded (12) and a clear option on conservative non-intervention should be considered with LV retraining reserved for selected patients only.All speakers highlighted the role of multimodality assessment of size, shape, deformation and function in understanding this challenging subject.
Interventricular Interactions in Congenital Heart Disease
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