Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (37 page)

Spontaneous Coronary Artery Dissection

   Occurs from vessel wall hematoma between media and adventitia in the absence of trauma or iatrogenic causes. Most diagnosed with autopsy and occur in LAD or left main artery.

   Described in young women with risk factors among whom 25–30% are pregnant or in the postpartum period. Likely etiologies include hormonal impairment of collagen synthesis. Oral contraceptive use also associated with dissection. Thrombolytic therapy should not be given in postpartum patients with STEMI due to increased chance of propagation of hematoma.

   Men are more likely to be older and have right coronary involvement with coronary risk factors. Systemic hypertension is not a risk factor for dissection.

   Other associated conditions include cocaine or cyclosporine use, hypertrophic cardiomyopathy, Marfan or Ehlers-Danlos syndrome, and immunemediated diseases such as rheumatic arteritis, autoimmune thyroiditis, hepatitis C infection, sarcoidosis, systemic lupus erythematosus, Kawasaki arteritis, and eosinophilic coronary arteritis.

   A careful family history of connective tissue disease, lab assessment for eosinophilia, ESR, ANA, and thyroid evaluation should be performed if coronary dissection is suspected.

Coronary Artery Spam

   Spasm that occurs within epicardial coronary arteries usually occurs at sites with non–flow-limiting luminal narrowing by atherosclerotic plaque. An abundance of smooth muscle cells is usually present in necropsy studies at the known sites of spasm.

   Hyperadrenergic conditions associated with spasm include pheochromocytoma, cocaine, amphetamine, and ecstasy use. This includes dobutamine infusion for stress testing. Epicardial spasm can be seen in inflammatory conditions of thyrotoxicosis, allergic angina, as well as administration of fluorouracil, capecitabine, sumatriptan, and bromocriptine.

   Diagnosis of spasm is usually made with angiography. Provocative challenge during catheterization with ergotamine is no longer performed due to risk of MI/death from refractory spasm. Potential offending medications or behaviors should be stopped immediately.

   Epicardial spasm should be differentiated from
Syndrome X
, or microvascular spasm. This syndrome carries a benign prognosis but presents with angina-like pain. Stress testing often reveals signs of ischemia with normal epicardial arteries on invasive testing (coronary flow reserve—which can be assessed invasively is often abnormal). Pain is likely due to either microvascular spasm or abnormal pain perception (sympathetic predominance).

Hypertrophic Obstructive Cardiomyopathy

   See Dyspnea/CHF section.

Suggested Readings

Angelini P, Trivellato M, Doris J, et al. Myocardial bridges: a review.
Prog Cardiovasc Dis.
1983;26:75–88.

Chetlin MD, Virami R. Myocardial infarction in the absence of coronary atherosclerotic disease. In: Virmani R, Forman MB (eds).
Nonatherosclerotic ischemic heart disease
. New York, NY: Raven Press; 1989:1–30.

CHEST PAIN: INFLAMMATORY

Chest pain may occur due to an inflammatory response to immune-mediated or infectious triggers without necessarily predisposing to ischemic insult. Pericardium, myocardium, or direct coronary artery involvement may occur. Ischemia may occur when coronary arteries are involved as a direct result of the inflammatory process (necrosis and aneurysm formation) or via wall thickening and luminal narrowing, rupture of the vessel wall, or from thrombosis due to hypercoagulable state or accelerated atherosclerosis.

VASCULITIS

   Definition