ECG challenge: beating at the right place at the right time

A 23-year-old obese male without any medical history presented with complaints of chills, nausea, and vomiting for the past 2 days. He was mildly febrile, tachycardiac, and normotensive. Cardiac review of systems was unremarkable otherwise. On physical examination, the patient had appropriately audible heart sounds on the right of the sternal border but diminished on left. The apical impulse was not palpable. The lab workup was unremarkable. A 12-lead electrocardiogram (ECG) was obtained and is shown below: What diagnosis is most closely represented in this ECG? Wolff–Parkinson–White Syndrome Right Heart Strain Dextrocardia Reversal of Arm Leads Right Ventricular Hypertrophy (RVH) The correct answer is C Classic ECG findings in dextrocardia include right or extreme axis deviation, positive QRS complexes in aVR, inversion of all complexes in lead I, and absent R-wave progression in precordial leads V1-V6 with dominant S waves. It is important to note that simply reversing the leads in the left and right arms would produce a very similar ECG finding which is why choice D is a tempting answer choice. After all, in clinical practice, the misplacement of leads is much more common than encountering true dextrocardia. However, the subtle differentiating finding will be the loss of R-wave progression in the precordial leads that would not have been seen in lead reversal. In the case of dextrocardia, one can clearly see the gradually diminishing amplitudes of the QRS complexes. One can correlate the low voltage in V6 seen here with our inability to palpate an apical impulse in that region on our initial physical exam. Simply mirroring the lead placements and relocating them to the contralateral side of the sternum will produce a normal sinus rhythm with normal wave orientations. Choice A is incorrect as there is no slurred upstroke of QRS complexes (delta wave). Choices B and E are also incorrect. Although both may have right axis deviation, none of the other hallmark findings discussed above are seen. Additionally, right heart strain findings on ECG may include right bundle branch block and the McGinn-White sign (prominent S wave in lead I, inverted T wave with concurrent Q wave in lead III) though neither is sensitive.1 T wave inversions in leads in V1-V4, III, and avF may also be seen. Choice E is tricky because in RVH, the R/S ratio is >1 or the R-wave is >7 mm in V1. It may appear that these criteria are both met in our ECG. However, keep in mind that these diagnostic criteria for RVH are under the assumption of a normal anatomical variant of the heart positioning—levocardia. Upon obtaining this ECG, we repeated our physical exam and realized the apical impulse was on the right. A chest radiograph was obtained which confirmed our suspicion of dextrocardia (see Supplementary material online, Figure S1). A computed tomography scan of the abdomen reveals total situs inversus (see Supplementary material online, Figure S2). What other symptom(s) might the patient likely have also acknowledged? Swelling and oedema Incontinence Chronic cough with wheezing Vision changes Jaundice The correct answer is C Dextrocardia in the presence of total situs inversus is associated with primary ciliary dyskinesia. Common symptoms of primary ciliary dyskinesia include chronic cough, wheezing, and excess mucus production. Answer options A, B, D, and E are incorrect. Primary Ciliary Dyskinesia is not associated with symptoms of oedema, urological disturbances, vision changes, or jaundice. Additional symptoms may include ear pain, sinus congestion, rhinorrhea, increased mucus production, as well as increased risks of otitis media and upper respiratory tract infections What is the most appropriate next step in evaluating this patient? Sperm analysis Complete echocardiogram Left heart catheterization Myocardial perfusion scintigraphy Computed Tomography of the Abdomen and Pelvis The correct answer is B Patients with dextrocardia and total situs inversus are more likely to have other cardiac anomalies such as ventricle septal defects and valvular anomalies. A is incorrect. Although infertility is more prevalent amongst patients with primary ciliary dyskinesia, an echocardiogram to rule out cardiac anomalies is more appropriate as the next best test. C and D are incorrect as Dextrocardia is not associated with coronary anomalies and ischaemic evaluation is not necessary. Our patient was ultimately diagnosed with cannabinoid hyperemesis. His dextrocardia and situs inversus totalis were incidental findings. He was referred to a tertiary centre for further outpatient evaluation and workup. ECG machine programmers have been unable to produce algorithms for current ECG machines to detect dextrocardia.2 In most instances, the programmed algorithm will lead to the study being incorrectly read as ‘suspected limb lead reversal.’ Being able to identify dextrocardia and differentiate it from limb lead misplacement is an important ability to develop proficiency in as it can help lead to other important diagnoses such as primary ciliary dyskinesia or heterotaxia. Such patients need to follow up closely outpatient with the appropriate specialists. Supplementary material is available at European Heart Journal – Case Reports. The authors would like to thank the Mercy Health - St. Rita's Medical Center Structural Heart Team and Department of Graduate Medical Education for their help and support. Consent: Direct written consent was obtained by the patient for this manuscript. Funding: No funding was involved in the development of this manuscript. The data that support the findings of this study are available from the authors upon request.