Xray Vision: Chest Pain Answer

The chest x-ray shows a widened mediastinum. This x-ray with a presentation of tearing chest pain, aortic dissection should be considered.

Blood enters the aortic media between the intimal and adventitial layers. The wall of the aorta is exposed to high pulsatile pressure and shear forces. This stress makes the aorta prone to injury.

Aortic dissection has a bimodal distribution. The younger population has conditions that predispose them to aortic dissection, such as Marfan syndrome, Ehlers-Danlos, Osteogenesis imperfecta, or Turner syndrome. In elder patients, hypertension is the most important predisposing factor for aortic dissection. Other causes of aortic dissection include: syphilitic aortitis, deceleration injury, or cocaine use.

DeBakey:

Type I- intimal tear occurs in the ascending aorta and involving the descending aorta.

Type II – Only ascending aorta is involved.

Type III – Only descending aorta is involved.

Stanford:

Type A – Ascending aorta is involved (DeBakey type I and II)

Type B – The descending aorta is involved (DeBakey type III)

Patients with acute aortic dissection typically present with SUDDEN onset of severe chest pain. However, for some patient the chest pain is only mild. Therefore, thoracic aortic dissection should be a part of the differential diagnosis for all patients with chest pain.

Location of the chest pain may provide indication where the dissection arises. Anterior chest pain is usually associated with anterior arch or aortic root dissection. This dissection can cause decrease flow to the coronary arteries, which results in myocardial ischemia. Pain in the scapular are may indicate that the dissection involves the descending aorta. Pain evolves as the dissection evolves. Dissecting into the carotid artery may present with stroke like symptoms. Dissection into the abdominal vessels may presents with abdominal pain.

EKG:

All patients suspected of having an aortic dissection should have a 12-lead EKG. Often times, the EKGs demonstrate nonspecific abnormalities or can even be normal. In acute thoracic aortic dissection, EKG changes can mimic those seen in myocardial ischemia. ST segment elevations can often be seen in Stanford type A dissections, because these types of dissections interrupt the blood flow to the coronary arteries.

Imaging:

Chest radiograph should be the initial imaging test, but not the definitive study. Widening of the mediastinum is the classic finding. Other chest xray abnormalities include: pleural effusion, tracheal deviation to the right, depression of the left mainstem bronchus, or esophageal deviation.

CT with contrast is used in HEMODYNAMICALLY stable patients. It is the definitive test and provides important information about the type of lesion, location of dissection, and extent of disease.

Blood tests:

Complete blood count, chemistry studies, and cardiac marker assays should be performed. Decrease in hemoglobin and hematocrit could suggest that the dissection is leaking or rupturing. Elevations in BUN/creatinine can indicate the renal artery involvement.

Surgical correction: preferred for Stanford type A (DeBakey type I and II) ascending aortic dissection. Also, surgical intervention is also preferred for complicated Stanford type B (DeBakey type III) aortic dissection with evidence of increasing aortic diameter, increasing size of hematoma, impending rupture, or bleeding into the pleural cavity.

Medical intervention: Use negative inotropic medications to reduce cardiac contractility and shearing forces. Consider beta-blockers: IV labetalol, IV propranolol, or IV esmolol. Contraindications for beta-blockers include: severe asthma, heart block, bradycardia, hypotension. Use calcium channel blockers if beta-blockers are contraindicated. Target to a BP of 120-130 systolic. IV nitroprusside may be added for further antihypertensive treatment after the administration of a negative inotrope medication.

 

Disposition:

Consult ICU. Patient should be admitted to an intensive care unit for hemodynamic monitoring.