Mass General Hospital
March 2009
ISSUE 15

 
 
Cardiac Arrest While Walking in the Park
Andrew R. Blum, MD, Robert Altman, MD, Brian Ghoshhajra, MD,
Suhny Abbara, MD, Wilfred Mamuya, MD, PhD

 
  Clinical History
A 49 year-old woman with a history of anorexia and borderline hypertension suffered a cardiac arrest while walking. She was defibrillated on-site, and a post-defibrillation ECG demonstrated non-specific ST segment depression in the inferior leads as well as apical T wave inversions. Upon admission to Massachusetts General Hospital, her cardiac troponin T was noted to be mildly elevated (0.95 ng/ml), although it was unclear if this was a result of defibrillation; and her potassium was low (2.9 mmol/L). When her memory improved, she gave a long-standing history of exertional chest discomfort, and a coronary CTA was ordered to exclude anomalous coronary arteries as the etiology of her presentation.

Findings
Coronary CTA demonstrated the absence of anomalous coronary arteries. However, surprisingly, it showed an occluded left anterior descending (LAD) artery with distal reconstitution by collaterals from the diagonal and acute marginal branches. There was associated hypokinesis of the mid anteroseptum and akinesis of the apical anterior and septal segments. A significant stenosis in the proximal first obtuse marginal branch of the left circumflex coronary artery was also noted. These findings were confirmed by catheter angiography the following day. She subsequently underwent coronary artery bypass surgery with a left internal mammary artery (LIMA)-LAD, saphenous vein graft (SVG)-ramus intermedius, and SVG-obtuse marginal  artery.

Figure 1. Curved multiplanar reconstruction of the left anterior descending (LAD) coronary artery demonstrates an occluded segment in the mid LAD segment (arrows). The distal LAD is reconstituted by collaterals.
Figure 1.

Figure 2. Curved multiplanar reconstruction of a patent left circumflex coronary artery (white arrows) demonstrates a proximal stenosis/occlusion at the origin of the first obtuse marginal branch (black arrows).
Figure 2.

Figure 3. 3D volume rendered image demonstrates occlusion of the LAD (white arrows) as well as proximal first obtuse marginal branch stenosis. (black arrow). A very large, tortuous, first diagonal branch is present carrying the bulk of the LAD blood flow (dotted arrow).
Figure 3.
Figure 4. Single view from the patient’s catheter coronary angiogram demonstrates similar findings, with long segment occlusion of the LAD (white arrows), large tortuous first diagonal branch collaterals (dotted arrow), and high grade stenosis in the proximal first obtuse marginal branch (black arrow).
Figure 4.


(Click on images to enlarge)


Figure 1. Curved multiplanar reconstruction of the left anterior descending (LAD) coronary artery demonstrates an occluded segment in the mid LAD segment (arrows). The distal LAD is reconstituted by collaterals.

Figure 2.
Curved multiplanar reconstruction of a patent left circumflex coronary artery (white arrows) demonstrates a proximal stenosis/occlusion at the origin of the first obtuse marginal branch (black arrows).

Figure 3.
3D volume rendered image demonstrates occlusion of the LAD (white arrows) as well as proximal first obtuse marginal branch stenosis. (black arrow). A very large, tortuous, first diagonal branch is present carrying the bulk of the LAD blood flow (dotted arrow).

Figure 4.
Single view from the patient’s catheter coronary angiogram demonstrates similar findings, with long segment occlusion of the LAD (white arrows), large tortuous first diagonal branch collaterals (dotted arrow), and high grade stenosis in the proximal first obtuse marginal branch (black arrow).



Discussion
The patient had a witnessed syncopal event, and prompt resuscitation in the field confirmed ventricular fibrillation (VF) as the cause of her cardiac arrest. The most common cause of a VF arrest is myocardial ischemia or infarction1. Other etiologies that carry an increased risk of VF include various cardiomyopathies, the Brugada syndrome, drowning, metabolic abnormalities such as acidosis or hypokalemia,  and side effects of medications that affect membrane ion conductance channels. Patients with anorexia carry a higher risk of VF secondary to hypokalemia or a prolonged QT interval2. In our case, her presentation was most likely secondary to hypokalemia with superimposed coronary artery disease. Cardiac CTA was useful in excluding coronary anomalies or cardiomyopathies, and led to the surprising diagnosis of premature multi-vessel epicardial coronary artery disease in a young woman without significant traditional risk factors.


 
 
REFERENCES
1. Olgin JE, Zipes DP. Specific Arrhythmias: Diagnosis and Treatment. In: Libby P, Bonow RO, Mann DL, Zipes DP. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 35
2. Vannacci A, Baronti R, Masini E, Ravaldi C, Ricca V. Anorexia nervosa and the risk of sudden death. The American Journal of Medicine Volume 112, Issue 4, March 2002, Pages 327-328
   

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Editors:
Suhny Abbara, M.D.
MGH Department of Radiology
Wilfred Mamuya, M.D., Ph.D.
MGH Division of Cardiology

Phone: 617-726-5954