VASCULAR COMPLICATIONS
Key Points
• The most common times for presentation of rupture or dissection of aneurysms during pregnancy are the third trimester, labor, or the puerperium.
• Intracranial hemorrhage (ICH) complicates approximately 3.7 to 9.0 per 100,000 pregnancies, and maternal mortality approaches 40%.
• The reported mortality for cerebral infarction is nearly 10%.
• Pregnant women with mechanical prosthetic heart valves are at high risk for thrombosis and thromboembolism and require close monitoring and therapeutic levels of anticoagulation.
• The optimal regimen for anticoagulation that minimizes both maternal and fetal risks is yet to be determined.
ANEURYSMS OF THE AORTA AND ITS BRANCHES
Background
Definition
• An aneurysm is the presence of a focal dilatation of all three layers of a vessel wall, in direct communication with the lumen, due to congenital or acquired weakness in the vessel wall.
• Dissection is present when an intimal tear occurs in a major vessel, allowing formation of an aneurysm.
• The three most common sites for intra-abdominal aneurysms: (a) aorta, (b) iliac arteries, and (c) spleen.
Pathophysiology
• All of the following factors have been reported to play a role in the risk of aortic dissection and rupture of arterial aneurysms during pregnancy:
• Congenital disorders including Marfan syndrome, Ehlers-Danlos syndrome, Turner syndrome, Loeys-Dietz syndrome, aortic coarctation, and the mucopolysaccharidoses (1).
• Takayasu arteritis, a chronic progressive granulomatous vaso-occlusive disorder of unknown etiology that primarily affects women of childbearing age (2).
• Trauma, infection, or cocaine abuse (1)
• Increased wall pressure in the proximal aorta, especially in late pregnancy, which may occur due to cardiovascular changes associated with pregnancy such as increased cardiac output, stroke volume, and blood volume (3)
• Changes in progesterone concentrations may alter vessel wall integrity.
Epidemiology
• In the absence of Marfan syndrome or Ehlers-Danlos syndrome, arterial aneurysms are uncommon in people less than 40 years of age.
• The most common times for presentation of dissection or rupture during pregnancy are the third trimester, labor, or the puerperium.
• Splenic artery aneurysms are four times more common in females than males, and 80% are discovered incidentally (4).
Evaluation
History and Physical
• Common symptoms of aortic aneurysm rupture or dissection include
• Sudden onset of chest or abdominal pain, often described as severe or “tearing.” Pain may radiate to midscapular area or be migratory.
• Nausea, vomiting, light-headedness, and other vasovagal symptoms.
• Pain or tingling in extremities.
• Neurologic symptoms such as syncope.
• The rupture of a splenic artery aneurysm will be associated with severe left upper quadrant pain or epigastric pain, left shoulder or flank pain, and hemodynamic instability (4).
• Physical findings with dissection or ruptured aneurysm may include
• Tachycardia, hypotension, or hypertension
• Anxiety
• Decreased pulses and blood pressure differences between extremities
Diagnosis
• Symptoms of aneurysmal rupture may mimic more common conditions, so a high index of suspicion is necessary. As this condition threatens maternal and fetal well-being, rapid diagnosis is imperative.
• Various imaging modalities are used to diagnose dissection and aneurysm rupture. Modalities that utilize ionizing radiation are not contraindicated (5).
• Magnetic resonance image (MRI) without contrast is the recommended first-line imaging study during pregnancy.
• Computed tomography (CT) of the chest (with shielding of the uterus) results in little fetal radiation exposure and has sensitivity equivalent to MRI.
• Chest radiography may show mediastinal widening, but a normal radiograph does not exclude the diagnosis.
• Echocardiography will demonstrate abnormalities of the thoracic aorta and is useful if the patient is clinically unstable.
• Abdominal ultrasound does not require radiation, but in late pregnancy, the gravid uterus may impede imaging of the abdominal aorta and its branches.
Treatment
• Immediate management should be aimed at maternal stabilization, including aggressive treatment of hypertension, if present, with an intravenous beta-blocker; administration of oxygen by face mask to optimize placental gas exchange; obtaining blood products for possible transfusion; and close maternal and fetal observation.
• Ascending aortic dissections (type A) require emergent surgical repair. Mortality rate may be as high as 1% to 3% per hour over the first several hours and up to 25% in the first 24 hours (1).
• Descending aortic dissections (type B) may initially be treated medically. When aortic dissection is diagnosed before the third trimester, surgical repair should be performed, but if the diagnosis is made in the third trimester and the dissection is stable, expectant management is preferred. Repair should be undertaken after cesarean delivery, either at or near term, or if maternal condition worsens (1).
• Splenectomy is the treatment of choice for a ruptured splenic artery aneurysm. Asymptomatic splenic aneurysms detected before or during pregnancy should be treated before term (6).
Complications
• Aortic rupture is frequently catastrophic, and mortality is high. As many as 50% of aortic dissections in women younger than 40 occur during pregnancy and the postpartum period, although pregnancy itself is unlikely to represent an independent risk factor (7).
• Splenic artery aneurysms are associated with 75% maternal mortality and 95% fetal mortality; combined maternal and fetal survival is rare (6).
• Renal artery aneurysms are rare. Rupture leads to retroperitoneal hemorrhage and is associated with a high mortality rate. This entity should be considered among the causes of retroperitoneal hemorrhage in pregnancy (8).
PREGNANCY-RELATED STROKE
• Rare but potentially devastating event estimated to occur in 34 per 100,000 deliveries with an estimated mortality rate of 1.4 per 100,000 deliveries (9,10).
• Risk factors for pregnancy-related stroke include age greater than 35 (OR 2.0), African American race (OR 1.5), migraines (OR 16.9), thrombophilia (OR 16.0), lupus (OR 15.2), heart disease (OR 13.2), hypertension (OR 2.61 to 10.39), thrombocytopenia (OR 6.0), sickle cell disease (OR 9.1), diabetes (OR 2.5), substance abuse (OR 2.3), smoking (OR 1.9), anemia (OR 1.9), and postpartum hemorrhage (OR 1.9) (9).
• Pregnancy-related stroke can be pregnancy induced or pregnancy incidental and categorized into two broad types: intracranial hemorrhage and ischemic (11).
• Treatment decisions are based on the type of stroke. History and physical are insufficient to answer the question, and imaging with CT or MRI should be done as quickly as possible after symptom onset.
• Other rare causes of pregnancy-related stroke include cardioembolism, paradoxical embolism, choriocarcinoma, amniotic fluid embolism, air embolism, and moyamoya disease.
INTRACRANIAL HEMORRHAGE
Background
ICH occurs in 3.7 to 9.0 out of 100,000 pregnancies (12). Approximately half are due to rupture of a saccular aneurysm or of an arteriovenous malformation (AVM), with the other half a consequence of hypertension or trauma. The highest risk for ICH occurs in the postpartum period (13).
Definition
• A saccular (berry) aneurysm is an aneurysm commonly found at the bifurcation of major vessels of the circle of Willis, with 85% occurring along divisions of the internal carotid artery. Multiple aneurysms are found in 20% of patients.
• An AVM results from congenital anomalies such as arteriovenous fistulae, resulting in direct arteriovenous shunting. They are seen most commonly in the frontoparietal and temporal regions but can occur anywhere in the brain.
• Other risk factors for AVM formation include family history of aneurysm, female gender, current cigarette use, or cocaine abuse (13).
Pathophysiology
• Controversy exists as to whether the risk of hemorrhage from AVMs is increased during pregnancy, with recent large retrospective cohort studies refuting a theory of increased risk. Any relationship is likely to be coincidental as the most common time for rupture is age 20 to 40 years, the prime childbearing years (13–15).
• The risk of rupture of a known AVM in pregnancy is estimated at 3.5%. Reasons given for an increased risk of bleeding include increased cardiac output and increased blood volume.
• The risk of rupture of a saccular aneurysm increases as pregnancy advances, possibly due to the increased blood volume of late pregnancy or due to hormonal fluctuations (14).
• Maternal hypertension or preeclampsia increases the risk of rupture.
Epidemiology
• AVMs occur in approximately 0.01% of the population (16) and are twice as common in men as in women.
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