Beta blockade prior to instituting other vasodilator drugs in aortic dessection management is essential. The following case presentation demonstates the importance of beta blockade in Aortic dissection management.
A 44-year-old man whose only past medical history consists of hypertension and unilateral cataracts presents to his local emergency department with the acute onset of severe tearing chest pain radiating to his back.
On exam the physician notes that the patient is 6 feet 8 inches tall with long, lanky fingers. The patient states that everyone in his family has been tall and lanky like him. His initial pulse rate is 105 and his blood pressure reads 185/95.
His electrocardiogram shows no ST-segment changes and initial laboratory tests show no abnormalities with a blood urea nitrogen level of 11 mg/dL and creatinine of 0.8 mg/dL. A computed tomography (CT) with intravenous contrast shows a 6-cm dilated descending thoracic aortic aneurysm with a dissection flap present.
He is immediately transported to the surgical intensive care unit (SICU) for management. In the SICU, the on-call resident orders hydralazine for blood pressure control. His heart rate climbs to 126 and his systolic blood pressure drops to 145 mm Hg.
Over the next 6 hours, despite these maneuvers, his pain does not improve and he becomes progressively tachycardic and hypotensive, initially responding to fluid but then requiring vasopressor support. Repeat laboratory analysis shows a serum lactate of 5.0 and a rising serum creatine to 1.8 mg/dL.
During this time he stops making urine and his abdomen becomes tender and progressively distended. He also develops a metabolic acidosis with a pH of 7.20, requiring intubation and mechanical ventilation for his increased work of breathing.
Immediate abdominal CT shows propagation of the dissection to involve the abdominal aorta with visceral vessel involvement and pneumatosis of the small intestine. He is immediately taken to the operating room but at this point requires massive vasopressor support and is profoundly acidotic.
Direct visualization inside the abdomen shows diffusely necrotic bowel. Approximately 45 minutes into the operation the patient suffers a cardiac arrest and despite cardiopulmonary resuscitation and administration of code drugs, the patient expires on the operating room table.
Discussion
The preceding case illustrates the necessity of treating acute aortic dissections with beta-blockade concomitantly with vasodilatory antihypertensives.
The patient described had the inherited connective tissue disorder Marfan syndrome with the classic presentation of an acute aortic dissection heralded by the acute onset of chest or back pain.
The patient received adequate antihypertensive therapy but continued to deteriorate because of the failure to initiate beta blockade.
To briefly review, aortic dissections can be classified according to the Stanford classification aortic dissection as type A (those involving the ascending aorta) and type B (those involving only the descending aorta).
Elective operative repair is preferable as mortality rates from urgent operative procedures for aortic dissection range between 2% and 21%.
Indications for operative repair include type A dissections with or without ulcers and type B dissections with visceral involvement or large, open free-flowing false lumens.
When urgent surgery is not indicated, management consists of pain control and blood pressure lowering to a target of 110 mm Hg systolic.
This is usually accomplished with sodium nitroprusside, but beta blockade is imperative because the pulsatile force must also be minimized with appropriate beta blockade so as to not propagate the dissection, and beta blockade decrease wall stress. Vasodilators by themselves can lead to reflex tachycardia, which can increase shear stress and propagate the intimal tear.