Vascular Emergencies
Syed M. Faisal Alam
Christopher H. Byrne
I. Introduction
The acute care surgeon is often called to evaluate and manage patients in the emergency department who have a vascular etiology for their complaints. Prompt recognition and treatment of the vascular pathology can diminish the morbidity and mortality associated with these vascular surgery conditions.
II. Ruptured Aortic Aneurysm
Introduction. An aneurysm is a permanent localized dilatation of a vessel that creates a 50% (1.5 times) or greater increase in its expected normal diameter.
Abdominal aortic aneurysm (AAA) is the most common form of true aneurysm. The most common location is below the renal artery. Thoracoabdominal aneurysms are less common and a larger treatment challenge.
It is estimated that 200,000 new AAA cases are diagnosed each year with more than 50,000 repairs done.
The incidence of detected AAA has tripled since 1970; the age-specific death rate from aneurysm rupture has also increased.
In the USA there are an estimated 15,000 deaths annually due to AAA, making it the 13th leading cause of death.
Rupture of an AAA is often a lethal event. The best way to reduce mortality is to identify and treat the lesion before rupture occurs.
Two randomized control trials, the Aneurysm Detection and Management (ADAM) trial and the UK Small Aneurysm Trial, support a threshold of 5.5 cm or greater to trigger elective repair.
A rapid increase in size (0.7 cm in 6 months or 1 cm in 1 year) should also be electively repaired.
Of note, women rupture more often and some advocate repair at a threshold size of 5 cm or greater.
Diagnosis
Risk factors for AAAs (Table 55-1)
Table 55-1 Independent Risk Factors for Detecting an Unknown 4 cm Diameter or Larger AAA during US Screening
Risk factor
Odds ratioa
95% CI
Increased risk
Smoking history
5.1
4.1–6.2
Family history of AAA
1.9
1.6–2.3
Older age (per 7-y interval)
1.7
1.6–1.8
Coronary artery disease
1.5
1.4–1.7
High cholesterol
1.4
1.3–1.6
COPD
1.2
1.1–1.4
Height (per 7 cm interval)
1.2
1.1–1.3
Decreased risk
Abdominal imaging within 5 y
0.8
0.7–0.9
Deep venous thrombosis
0.7
0.5–0.8
Diabetes mellitus
0.5
0.5–0.6
Black race
0.5
0.4–0.7
Female gender
0.2
0.1–0.5
From Lederle FA, Johnson GR, Wilson SE, et al. The aneurysm detection and management study screening program: validation cohort and final results. Aneurysm Detection and Management Veterans Affairs Cooperative Study Investigators. Arch Intern Med 2000;160:1425
AAA, abdominal aortic aneurysm; CI, confidence interval; COPD, chronic obstructive pulmonary disease.
aOdds ratio indicates relative risk in comparison to patients without that risk factor.
History and physical examination
The classic manifestations of ruptured AAA consist of diffuse back/flank or abdominal pain, shock, and a pulsatile abdominal mass. Classic presentations are not common—often, one or more feature is absent.
The presence of aneurysm is known only in 25% to 33% of patients before rupture.
Pain, most commonly occurs on the left side since the left posterolateral wall, is the most common site of rupture.
The duration of symptoms may vary from a few minutes to up to 24 hours. Although free aneurysm rupture is a catastrophic event, the hematoma can be contained for prolonged periods.
Imaging modalities
CT scan
CT is most commonly used modality for diagnosis of AAA. The preferred way to diagnose and plan any operation is a CT angiogram with fine cuts; this is often not possible in unstable patients or in patients with abnormal renal function.
Ultrasound (US)
Abdominal US is a useful bedside tool in trained hands. US is user dependent. It is not useful for the suprarenal aorta and is unreliable for defining relationship between aortic aneurysm and renal arteries. Examination is limited to presence of AAA and presence of free fluid.
MRA or traditional angiogram
There is no role of either of the modalities in diagnosis of ruptured AAA.
Treatment
Urgent operation is required in the setting of a presumed ruptured AAA.
Standard adjuncts for management include large-bore IVs, central venous access, airway control, permissive hypotension, and foley catheter. Immediate availability of blood products is mandatory as part of operative planning.
Permissive hypotension involves controlled resuscitation of patients to an SBP of 80 to 90 mm Hg for temporarily adequate end organ perfusion but not to exceed 100 mm Hg.
Skin preparation and draping include chest, abdomen, and thighs prior to induction.
Operative strategies
Open repair
Midline incision (retroperitoneal approach also well described).
Recognition of retroperitoneal staining demands supraceliac control via opening gastrohepatic ligament, exposure of aorta by dividing crus of diaphragm. A nasogastric tube allows identification and protection of the esophagus.
Mobilize duodenum to the right
Proximal and distal aortic control.
Open aneurysm, oversew lumbar branches.
Graft sewn in place; rapid repair with a tube graft if possible.
The shortest operation with least systemic physiologic insult is key to improved outcomes.
Iliac aneurysms up to 3 to 4 cm diameter can be repaired in a delayed fashion unless they are the source of rupture.
Inferior mesenteric artery (IMA) perfusion
Safety of IMA ligation based on collateral pathways–-patients with underlying celiac or superior mesenteric artery (SMA) occlusive lesions, previous bowel resection, significant pelvic occlusive disease and patients with hypotension in the perioperative period are at risk.
Presence of back-bleeding of the IMA in addition to normal appearing colon would indicate ability to ligate the IMA.
Ligation is performed from within aneurysm sac to prevent ligation of branches of IMA.
Aneurysm sac closed over repair, retroperitoneum closed, and abdomen closed.
Endovascular repair
An area under investigation in vascular surgery.
Recent studies suggest improved outcomes in centers with endovascular ruptured AAA programs.
Outcomes
Eighty to ninety percent of patients with ruptured AAA die before reaching a hospital.
Mortality of patients reaching the operating room is about 50%.
Patients need to be monitored in the ICU postoperatively. Appropriate restoration of volume and use of blood and blood products – including platelets and FFP – optimizes outcomes.
Bowel ischemia is a common postoperative problem.
Endovascular repair has better perioperative morbidity and mortality compared to open repair.
III. Visceral Aneurysms
Introduction
Visceral arterial aneurysms are an uncommon but important vascular disease. Nearly 22% of these aneurysms present as surgical emergencies including about 9% resulting in death. The major visceral vessels involved with these aneurysms in decreasing order of frequency are the splenic, hepatic, SMA, and celiac arteries.
Presentation
Most are asymptomatic and diagnosed as an incidental finding
If symptomatic
Pain is the most common symptom
Palpable mass depending on the size and location of the aneurysm
Hemorrhage
Intra-abdominal
GI bleeding
Hemobilia
Diagnosis
Most patients with rupture are diagnosed either in the operating room during exploration or with a pre-op contrast enhanced CT scan. Patients with non-ruptured but symptomatic aneurysms are diagnosed with a combination of CTA, US, and angiography.
Affected vessels
Splenic artery
Sixty percent of all reported visceral aneurysms.
Associated with grand multiparas, medial fibrodysplasia, portal hypertension, and pancreatitis.
Vague abdominal discomfort.
Double rupture phenomenon (initial bleeding contained in the lesser sac followed by free intraperitoneal hemorrhage).
Rupture not associated with pregnancy has 25% mortality.
Rupture associated with pregnancy has 70% maternal and 75% fetal mortality.
Treatment options
Aneurysm resection with interposition graft or primary anastomosis
Percutaneous transcatheter embolization
Endovascular stent graft exclusion of splenic artery aneurysm
Splenectomy, excision of the aneurysm
Hepatic artery
Twenty percent of all visceral aneurysms.
Most are false aneurysms.
Secondary to trauma to the liver, biliary tract procedures. Seventeen percent of hepatic artery aneurysms are related to liver transplant.
Most are asymptomatic but may cause right upper quadrant pain and epigastric pain.
Large aneurysms of hepatic artery may cause obstructive jaundice.
Rupture carries 35% mortality.
May cause hemobilia or free intraperitoneal hemorrhage.
Treatment options
Common hepatic artery aneurysms are generally treated with aneurysmectomy or aneurysm exclusion.
Percutaneous transcatheter obliteration of hepatic artery aneurysms with balloons, coils, or thrombogenic particulate matter is an endovascular alternative.
SMA
Aneurysm of the proximal SMA is the third most common visceral aneurysm accounting for 5% of these lesions.
SMA aneurysms are related to medial degeneration, periarterial inflammation, and trauma.
Aneurysm rupture or dissection is rare.
May occlude and cause hemodynamic instability from intestinal ischemia.
Mycotic aneurysm secondary to bacterial endocarditis is well described.
Treatment options
Ligation and aneurysmorrhaphy is the most common means of managing these lesions.
Aneurysmectomy or simple ligation of vessels entering or exiting the SMA aneurysm may necessitate intestinal revascularization by means of aortomesenteric bypass.
Endovascular treatment has appeal for certain SMA aneurysms (saccular) or in high risk patients.
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