GENERAL MEASURES:
. Treatment of choice - surgical for all ascending aortic dissections and medical for descending dissections
without complications (Type III)
. Medical therapy is based on decreasing blood pressure and the shearing forces of myocardial contractility (dp/dt) to attempt to decrease intimal tear and hematoma propagation
. Arterial blood pressure monitoring is critical
. Careful observation for changes in mentation, neurological signs, or evidence of organ dysfunction
. A Foley catheter should be used to follow urine output
. Swan-Ganz catheterization may be very helpful to monitor cardiac performance and fi lling pressures during
the use of vasoactive and cardio-depressive drugs
. Pain control may be diffi cult despite use of narcotics
SURGICAL MEASURES
. Surgical indications for Type III
. Increasing size of hematoma
. Impending rupture
. Inability to control pain
. Bleeding into pleural space
. Endovascular stents, fenestration, and stent-grafting
DRUG(S) OF CHOICE Propranolol in 0.5-1
mg IV doses every 5 minutes until the heart rate is
60-70 beats per minute plus nitroprusside titrated to
reduce systolic blood pressure to 100-110 mm Hg
(13.3-14.6 kPa)
Contraindications:
. Propranolol - in bronchial asthma, diabetes mellitus,
Raynaud disease, sinus bradycardia, A-V heart block
greater than fi rst degree, in presence of monoamine
oxidase inhibitors, cardiogenic shock, congestive
heart failure or right ventricular failure from pulmonary
hypertension
. Nitroprusside - in treatment of compensatory hypertension,
i.e., arteriovenous shunt, in patients with
inadequate cerebral circulation, and for use during
emergency surgery in moribund patients
Precautions:
. Use propranolol cautiously in patients with angina
pectoris, cardiac failure, impaired renal or hepatic
function, thyrotoxicosis, pre-excitation syndromes,
diabetes, hypoglycemia or nonallergic bronchospasm.
Propranolol may produce signifi cant bradycardia, heart
block or hypotension. Patients should not be suddenly
withdrawn from beta blockers.
. Nitroprusside:
. May not lower blood pressure adequately, another
agent may be required
. In patients with renal or hepatic insuffi ciency, may
cause cyanide toxicity, through excessive production
of serum thiocyanate. Confusion and hyperrefl exia
are the early signs of thiocyanate toxicity. Thiocyanate
inhibits the uptake and binding of iodine, use
caution in the presence of hypothyroidism. Check
thiocyanate levels after 48 hours of nitroprusside use.
. Because of the rapid onset and potency, administration
should be with the use of an infusion pump
. Methemoglobinemia may be seen rarely
ALTERNATIVE DRUGS
β’ Labetalol, 10-20 mg IV bolus to a maximum of 300 mg
total, then titrated to response with an infusion
β’ Trimethaphan, at an infusion rate of 1-2 mg/min
β’ Reserpine 0.5-2 mg intramuscularly every 4-8 hours.
Onset of action is 1-3 hours.
β’ Methyldopa 250-500 mg every 6 hours. Unfortunately,
it has a delayed onset of action of 4 to 6 hours and
prolonged duration of 10 to 12 hours.
PATIENT MONITORING
β’ Systolic blood pressure should be maintained at 120
mm Hg (16 kPa) or below as tolerated
β’ Routine chest x-rays and/or chest CT may be helpful
in following the progress of any long-term medically
treated patient
β’ Patients should have a one month follow-up visit, and
then at three month intervals. During the follow-up,
careful attention should be placed on signs and
symptoms of aortic insuffi ciency, chest or back pain,
and development of saccular aneurysms as displayed
on CXR.
POSSIBLE COMPLICATIONS Redissection,
localized saccular aneurysm, cardiac tamponade,
aortic valvular insuffi ciency and progressive aortic
enlargement
EXPECTED COURSE/PROGNOSIS
β’ Mortality of patients left untreated is: 33% in 24 hours,
60% in 2 weeks, approximately 90% in three months
β’ Hospital survival is estimated at approximately 70% in
patients treated both medically and surgically
β’ Patients with ascending dissection treated early with
surgery still have a mortality of 29-38%
β’ 10 year survival of all operated patients is 40%
β’ Redissection risk is 13% at 5 years; 23% at 10 years