Case No. 12: Eerily Calm
A 35 yr old white male presents to EMS with 20 minutes of 8/10 burning epigastric discomfort and left arm numbness. He denies nausea and shortness of breath; he is non-diaphoretic. He appears fit, healthy, and eerily calm.The pt. relates that this is not his “typical heartburn.” The only thing it reminds him of is when, 10 years ago, “a truck I was working on fell on my chest.” His BP is 180/110; his glucose is 399mg/Dl. He states that he has no medical history and has not seen a doctor in years. His father had an MI at 45, and died of another at 56; his mother died of an MI when she was 53. Social history reveals 16 pack-years of smoking.
The following EKG was recorded on arrival at the ED:The initial prehospital 12-lead in this case demonstrates a junctional tachycardia with ST elevation in V2-5, I, and avL; reciprocal depressions are suggested in V6, III, and avF sealing the diagnosis acute anterolateral MI. Evidence of an inverted P-wave buried within the QRS complex may be appreciated in the first deflection of the depolarizations in lead I. Sinus tachycardia supervenes in the second and third prehospital 12-leads, as well as the tracing obtained on arrival in the ED. Note the dramatic Q waves and loss of R-wave progression seen across the precordium, often a valuable tool for differentiating STEMI from benign early repolarization. Also of interest in this case is the 7th complex seen in the third prehospital tracing. The QRS morphology here reflects that of the initial junctional rhythm, while the p-wave preceding the complex remains normative, perhaps indicating an event of junctional fusion.
Contiguous precordial ST elevations are typically associated with lesions of the LAD and circumflex. Although the majority of coronary systems are right-dominant with the AV nodal branch arising from the distal RCA, in a left-dominant system the AV node is perfused by a distal branch of the left circumflex. Thus, while the specific anatomy remains unknown here, the presence of junctional tachycardia may reflect an irritable AV nodal focus resulting from circumflex disease in the setting of left-dominance. The graphics below illustrate these coronary variants.
Anterior views of the coronary arterial system, with the principal variations. The right coronary arterial tree is shown in magenta, the left in full red. In both cases posterior distribution is shown in a paler shade. A, The most common arrangement. B, A common variation in the origin of the sinuatrial nodal artery. C, An example of left ‘dominance’ by the left coronary artery, showing also an uncommon origin of the sinuatrial artery. (Text and images retrieved from: http://pgmcqs.com/2011/05/17/anatomy-thorax/)
Coronary angiography in this case revealed an 85% proximal occlusion of the left circumflex, a 60% proximal occlusion of the first diagonal branch and a 40% diffuse occlusion of the second diagonal branch. Stents were deployed across the two more serious lesions, reducing their stenosis to 0% post procedure. A 22-minute DTB time was recorded. Documentation of cardiac enzymes was not available at the time of follow up, however this pt made a good recovery and was discharged several days post PCI.