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Chest pain one week after childbirth.

[FIGURE 1 OMITTED]

What is your diagnosis?

DIAGNOSIS: Left posterior fascicular tachycardia, acute anterior-lateral myocardial infarct due to occlusion of the left anterior descending coronary artery proximal to the first diagonal and first septal perforating branches.

The QRS complexes are monomorphic and regular at a rate of 105/min. Although there are some irregular artifacts in the baseline, none of these resemble the P waves seen on the patient's subsequent ECGs. The QRS complexes are 0.12 seconds in duration and have the pattern of right bundle branch block (late broad R wave in lead V1) and left anterior fascicular block (QRS axis of -75 degrees with a qR pattern in leads I and a VL and an rS pattern in leads II, III, and aVF). Such tachycardias with a bifascicular-block morphology are generally thought to arise in or near the third fascicle of the ventricular conduction system, and, thus, this would be considered a left posterior fascicular tachycardia. (1) As Josephson has pointed out, proof of a fascicular origin and the rhythm's difference from other ventricular tachycardias is often lacking. (2) Alternatively, this could be a junctional tachycardia with right bundle branch block and left anterior fascicular block, but such a rhythm would be much less likely than ventricular tachycardia in a patient with an acute anterolateral myocardial infarct.

Although localizing the site of a coronary occlusion from an ECG with ventricular tachycardia is a less than certain undertaking, using criteria derived from studies of patients with sinus rhythm sometimes can be revealing. The ST-segment elevation in leads I, aVL, [V.sub.1]-[V.sub.3] indicate an anterior-lateral infarct due to occlusion of the left anterior descending coronary artery. The Q wave in lead aVL suggests that the occlusion is proximal to the origin of the first diagonal branch. Complete right bundle branch block and the absence of Q waves in the lateral precordial leads suggest that the occlusion is proximal to the first septal perforating branch. ST-segment depression [greater than or equal to] 1.0 mm in the inferior leads indicates that the occlusion is proximal to both the first diagonal and the first septal branches. (3)

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Acute myocardial infarction in a woman this age is extremely unusual and rarely is due to atherosclerosis in a woman with multiple risk factors for coronary disease. (4) Also rare is infarction in the absence of demonstrable coronary atherosclerosis, in which case coronary arterial spasm, at times associated with cocaine use, is thought to play an important role. (5) In a 24-year-old woman who has no classical risk factors for coronary disease and is in the early post-partum period, coronary arterial dissection is by far the most likely cause of the infarct. (6,7) Urgent coronary arteriography with intravascular ultrasound revealed a dissection beginning at the origin of the left anterior descending coronary artery before any of its branches and extending into its mid portion. The dissection was successfully stented, and an electrocardiogram recorded 2 1/2 hours after the first one showed normal sinus rhythm and a striking decrease in ST-segment deviation (Figure 2).

Spontaneous, ie, unrelated to iatrogenic trauma, coronary arterial dissection (SCAD) was first described at autopsy in 1931 (8) and at coronary arteriography in 1973. (9) As of 2005, nearly 250 cases had been described, most of them discovered by coronary arteriography after 1989. (10) In patients [greater than or equal to] 50 years old with SCAD, underlying coronary atherosclerosis is common, and approximately one-half of the patients are women. In contrast, of those < 50 years old over two-thirds are women, and atherosclerotic disease is uncommon. (10) Among young women with SCAD many are in the late stages of pregnancy or, more frequently, are early postpartum, as was our patient. (6,7,11) These also are peak times for aortic dissection in young women.

Successful treatment of SCAD by stenting was first described in 1996, (12) and a number of similar reports have subsequently appeared. (10,11,13,14) Because no randomized trials are available, and may never be because of SCAD's relatively infrequent occurrence, the choice of stenting, bypass operation, or conservative management necessarily is currently made on a case-by-case basis using anecdotal information. (10,14)

REFERENCES

1. Cohen HC, Gozo Jr EG, Pick A. Ventricular tachycardia with narrow QRS complexes (left posterior fascicular tachycardia). Circulation 1972;45:1035-1043.

2. Josephson ME. Clinical Cardiac Electrophysiology: Techniques and Interpretations, 3rd edition. Philadelphia: Lippincott Williams & Wilkins; 2002:431.

3. Engelen DJ, Gorgels AP, Cheriex, EC, et al. Value of the electrocardiogram in localizing the occlusion site in the left anterior descending coronary artery in acute anterior myocardial infarction. J Am Coll Cardiol 1999;34:389-395.

4. Glancy DL, Shah A, Azzam R, et al. Risk factors among medically indigent women < 45 years old with angiographically proven obstructive coronary arterial disease. J La State Med Soc 2002;154:86-90.

5. Daveron EJ, Glancy DL. ST-segment elevation myocardial infarction in young persons without angiographically demonstrable coronary arterial disease. J Invest Med 2004;52 (Suppl1):S308.

6. DeMais SJ, Kinsella SH, Silverman ME. Clincal course and long-term prognosis of spontaneous coronary artery dissection. Am J Cardiol 1989;64:471-474.

7. Koul AK, Hollander G, Moskovits N, et al. Coronary artery dissection during pregnancy and the postpartum period: two case reports and review of literature. Cathet Cardiovasc Intervent 2001;52:88-94.

8. Pretty HC. Dissecting aneurysm of coronary artery in a woman aged 42: rupture. Brit Med J 1931;1:667.

9. Forker AD, Rosenlof RC, Weaver WF, et al. Primary dissecting aneurysm of the right coronary artery with survival. Chest 1973;64:656-658.

10. Mohamed W, Norred T, Khuri BN, et al. Stent treatment of spontaneous coronary arterial dissection in patients with known coronary arterial disease. J La State Med Soc 2005;157:23-27.

11. Porras MC, Ares MA. Intracoronary stenting for postpartum coronary artery dissection. Ann Intern Med 1998;128:873.

12. Hong MK, Satler LS, Mintz GS, et al. Treatment of SCAD with intracoronary stenting. Am Heart J 1996;132:200-202.

13. Leclerc KM, Mascette AM, Schachter DT. Spontaneous coronary artery dissection in a young woman treated with extensive coronary stenting. J Invas Cardiol 1999;11:237-241.

14. Moukarbal GV, Alam SE. Spontaneous coronary artery dissection: management options in the stent era. J Invas Cardiol 2004;16:333-335.

Ghiath M. Mikdadi, MD; and D. Luke Glancy, MD

Dr. Mikdadi is a cardiologist with the Ochsner Medical Center and practices in Hammond and Baton Rouge. Dr. Glancy is a professor in the Section of Cardiology in the Department of Medicine, Louisiana State University Health Sciences Center, New Orleans.
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Title Annotation:ECG of the Month
Author:Mikdadi, Ghiath M.; Glancy, D. Luke
Publication:The Journal of the Louisiana State Medical Society
Article Type:Report
Date:Nov 1, 2010
Words:1102
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