Dextroversion of the heart is a subgroup of dextrocardias, It includes the location of the heart in the right hemithorax without inversion of the cardiac chambers. This congenital anomaly is the result of a counter-clockwise rotation of a normally developed heart in the right hemithorax. This condition has been described as an isolated phenomenon, as well as associated with different intracardiac and/or pulmonary anomalies. The heart, however, may be positioned in the right hemithorax due to intrinsic factors, such as major pathology of the right lung or pleura. There is no rotation of the heart in such cases, and the heart is simply drawn into the right hemithorax. This condition is mostly acquired and named dextroposition.
The terms dextroversion and dextroposition are sometimes interchanged, and different conditions are denoted by the same name, or vice versa-different terms are used for the same condition.
The diagnosis of dextroversion of the heart is based on the clinical, roentgenologic, electrocardiographic or catheterization findings. On physical examination, in addition to the right-sided heart, the maximum impulse is felt near the sternum, and is caused by the anteriorly placed left ventricle and by the parasternal, anterior, ascending aorta. Abnormal auscultatory findings are present only when dextroversion is complicated by intracardiac anomaly.
In dextroposition of the heart normal cardiac chamber arrangement is present with more or less normal silhouette. The heart may be somewhat distorted by an underlying lung pathology.The apex of the heart is discernible to the left of the sternum or behind it, since the pulmonary or pleural pathology may pull the heart in toto, but does not rotate its apex and left ventricle anteriorly.
In dextroversion of the heart the electrogram finding extreme counterclockwise rotation of the heart with normally placed atria. The electrocardiogram in dextroposition of the heart does not show this type of ventricular rotation and approaches normal.
Cardiac catheterization is helpful in proving the normal position of the caval veins, the marked rotation of the ventricles by the right turn of the catheter from the right atrium into the right ventricle, and by the right to the left direction of the main pulmonary artery. These feature is not found in dextroposition of the heart.
All the above mentioned clinical, radiologic, electrocardiographic and catheterization findings may be changed and complicated by additional congenital anomalies of the heart or lungs, which though not infrequent-are not necessarily present.