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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.

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Figure 1. Resting electrocardiogram demonstrates normal sinus rhythm with T-wave inversion in I, aVR, and V1–V6.

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Figure 2. Four-minute electrocardiogram at the completion of AdenoEx treadmill exercise demonstrating worsening of the baseline abnormalities with mild ST depression inferiorly and apically.

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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.

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Figure 3. Anterior view of the raw images demonstrating the heart on the right and reverse placement of the abdominal organs in situs inversus.

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Figure 4. Perfusion imaging with stress images above the resting images. Perfusion demonstrates a small fixed distal anterior wall consistent with breast attenuation (arrow), and in the vertical long-axis views (the third and fourth lines or perfusion images), the normal “short” septum on the right side of the lower vertical long-axis images compared with the longer lateral wall on the left side.

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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.

Conclusions

  1. Top of page
  2. Conclusions
  3. References

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.

References

  1. Top of page
  2. Conclusions
  3. References
  • 1
    Slart RH, De Boer J, Jager PL, et al. Added value of attenuation-corrected myocardial perfusion scintigraphy in a patient with dextrocardia. Clin Nucl Med. 2002;27(12):901902.
  • 2
    Turgut B, Kitapci MT, Temiz NH, et al. Thallium-201 myocardial SPECT in a patient with mirror-image dextrocardia and left bundle branch block. Ann Nucl Med. 2003;17(6):503506.