Situs Inversus With Dextrocardia in the Nuclear Lab
Article first published online: 14 FEB 2008
2008 by Le Jacq
American Heart Hospital Journal
Volume 6, Issue 1, pages 60–62, Winter 2008
How to Cite
Thomas, G. S. and Kawanishi, D. T. (2008), Situs Inversus With Dextrocardia in the Nuclear Lab. American Heart Hospital Journal, 6: 60–62. doi: 10.1111/j.1751-7168.2008.07779.x
- Issue published online: 14 FEB 2008
- Article first published online: 14 FEB 2008
A 73-year-old woman with a history of situs inversus, hyperlipidemia, and hypertension was referred for cardiology evaluation for increasing exertional and nonexertional chest pain. Dual-isotope myocardial perfusion imaging with a 4-minute adenosine with 1.0 mph at 0% grade of concomitant treadmill exercise (AdenoEx) was performed. Her heart rate increased from 72 to 101 bpm, with chest pain that was different than her index symptoms. Placement of the electrocardiographic electrodes was performed in the mirror image of what is typical, with the left leg lead placed on the right leg and the precordial leads starting on the left chest and extending over the right chest. Resting and 4-minute electrocardiograms are shown in Figures 1 and 2.
Given the dextrocardia, 180-degree imaging was performed on a dual-head camera from the left anterior oblique to right posterior oblique rather than the usual right anterior oblique to left posterior oblique. This is analogous to previous approaches.1,2
An anterior view of the raw images demonstrates the heart on the right and the liver on the left (Figure 3). Gated single photon emission computed tomography demonstrated normal left ventricular wall motion and an estimated ejection fraction of 80%. Perfusion is shown in Figure 4.
Perfusion imaging demonstrated a small fixed distal anterior wall defect consistent with breast attenuation. The vertical long-axis images (the third and fourth lines of perfusion images in Figure 4) are striking in the short length of the muscular septum compared with the longer lateral wall. This difference is part of the normal perfusion “Gestalt” used by experienced interpreters.
Medical treatment was continued; following assurance of a good prognosis, the patient's symptoms abated considerably.
Both the electrocardiogram and the perfusion images can be “normalized” in patients with dextrocardia by left-to-right reversal of electrocardiogram lead placement and nuclear scan planes. Interpretation can be facilitated by reversing the otherwise abnormal findings in this manner. The perfusion images also highlight the normal difference in length between the septum and lateral wall as seen in the vertical long-axis views, regardless of cardiac position.