Endovascular Complications

Christopher S. Eddleman, Stacey Quintero Wolfe, Roham Moftakhar, and Mohammad Ali Aziz-Sultan

Cerebrospinal angiography is a set of invasive procedures that can result in significant morbidity and (very rarely) even in death. While the risks of complications are generally low, it is the effects of the complications that matter most, for example, blindness, quadraparesis, limb ischemia, etc. Some complications may occur irrespective of the preparations; however, most endovascular complications can be avoided with meticulous and careful angiographic technique. In this chapter, we discuss the most common complications, techniques to avoid them, and finally the steps that must be taken when complications occur. Just remember, angiography and endovascular management may have low complication risks and fewer days in the hospital, but they also have a great potential to hurt someone if every procedure is not taken seriously.

Vascular Access and Closure Device Complications

Vascular access and closure complications are important considerations, given that they may become involved in every diagnostic and interventional procedure. Vascular access complications, which are reported in roughly 2% of those undergoing femoral artery catheterization (both diagnostic and interventional), include groin hematomas (1.3%), retroperitoneal hematomas (0.4%), pseudoaneurysms (0.1%), and arterial dissections (0.3%).1 The rates of complication are higher in patients receiving anticoagulation or antiplatelet therapy during interventional procedures.

Retroperitoneal hematomas can be life threatening, in rare cases leading to shock and cardiovascular collapse. Patients with abdominal or flank pain should immediately be screened with a CT of the abdomen, have hematocrits checked every 4–6 hours until stable, and receive transfusion accordingly. Additionally, antiplatelet and anticoagulation therapy should be stopped and reversed with platelets and protamine sulfate if there is a significant decrease in the hematocrit and the endovascular procedure allows for reversal. A decrease in hematocrit can be a late finding in retroperitoneal hematoma. Often, the first sign is relative hypotension that is unresponsive to intravenous fluid administration. This should prompt an emergent CT of the abdomen and pelvis.

Pseudoaneurysms can be prevented with proper closure technique and prevention of hip flexion for 24–48 hours following the procedure. In the case of a patient presenting with an enlarging, pulsating groin mass following angiography, an ultrasound should be performed immediately, and the patient should be referred to a peripheral vascular surgeon for evaluation. In the case of small pseudoaneurysms (approximately <2 cm), manual compression or thrombin injection may be sufficient, while in larger ones (>2 cm), open or endovascular treatment is required, and it is usually performed by a vascular surgeon or interventional radiologist. Another complication of a pseudoaneurysm may be an arteriovenous fistula, requiring close follow-up and potentially an intervention to correct the fistula. The risk of fistula formation is much higher when the patient is anticoagulated during the procedure.

Vessel wall injury or dissection may occur as the vessel is cannulated with the wire or sheath, creating a false lumen within which blood flows. This risk can typically be lowered by performing a single-wall puncture with slow advancement of the wire in a twisting motion under fluoroscopy. As a result, some advocate use of a micropuncture needle. In the case of dissection, angiography should be performed to assess limitation of flow, and there should be consultation with vascular surgery and interventional radiology to assess the potential need for stent placement.

There is excellent collateral circulation in the lower extremities, usually allowing for the loss of one arterial branch; however, the loss of the common femoral artery can result in vascular claudication and even profound ischemia requiring revascularization. Most thromboembolic events that occur with vascular access are due to distal showering of calcified plaque in patients with significant peripheral atherosclerosis. Loss of distal pulses requires an emergent ultrasound of the leg to evaluate the level of occlusion. If there is flow below the popliteal artery, this condition can usually be managed with intravenous heparin; however, more proximal thromboses typically require endovascular or surgical intervention. Stenosis of the common femoral artery is almost always due to failure of a closure device. Closure devices are not recommended in arteries with significant atherosclerosis.

Closure Devices

Closure devices are being used more often in neuroendovascular procedures in an attempt to prevent potential complications associated with anticoagulation and antiplatelet therapy. In a single-center study of 1,443 neurointerventional procedures, AngioSeal (St. Jude Medical) was used for 745 diagnostic procedures and 670 neurointerventions.2 The procedural success rate was 99.7%. Major complication rates related to closure were 0.13% in the diagnostic group and 1.4% in the interventional group. Angioseal did not appear to enhance inflammatory response when compared with mechanical compression.³

In a large meta-analysis of coronary angiography (30 studies, 37,066 patients), no difference between Angioseal or Perclose and mechanical compression was seen in diagnostic procedures.⁴ There was a trend toward fewer complications with AngioSeal in the interventional setting.

In another study examining lower extremity ischemia after cardiac catheterization in patients with peripheral vascular disease, neither AngioSeal nor Perclose was associated with a reduction in the ankle-brachial index when compared with manual compression.⁵

Two of the more recent closure devices on the market, namely the StarClose and the Mynx closure device, have recent studies regarding efficacy. McTaggart et al. reviewed their institutional experience with StarClose and reported a 0.7% and 0.4% rate in minor and major complications with a 95% success rate in patients with an attempt.⁶ However, Chiu et al. reported increased minor complications with the Starclose closure device as compared with others, but all were managed with additional manual compression.⁷ The Mynx closure, which involves deployment of a sealant plug, was reported by Fields et al. to be associated with an increased presence of intravascular sealant and pseudoaneurysms (11%) without major complications.⁸

Procedure-Related Complications

While vascular access and closure complications are probably the most common due to their presence in every endovascular procedure, several complications exist that are procedure specific. These complications can typically be classified into equipment/implant and/or post-procedure related. All of these complications must be vetted with the patient and their family to truly obtain and maintain informed consent for any procedure.

Equipment- and Implant-Related Complications

Radiation

As stated in Chapter 5, enough cannot be said regarding radiation safety. The effects of radiation are often taken for granted, especially given its invisibility and potential for long-term effects. Despite this, awareness of the complications of excessive radiation is imperative, both to the patient as well as to the interventionists and those in and around the immediate working area. Obviously, quantification of radiation to the patient and interventionist involves many factors, so that every situation will be different. A diagnostic angiogram should involve a significantly lower amount of radiation than embolization of an intracranial arteriovenous malformation (AVM). However, procedures can be instituted that significantly reduce the risks of prolonged radiation exposure in every case. The reported complications of excessive radiation exposure tend to be delayed malignancy, growth retardation, lenticular opacities, premature atherosclerotic disease, and mental retardation after in utero exposure.

More short-term effects of radiation exposure or concentration can be local skin reactions, edema, hair loss, and changes in constitution, such as nausea and headache. Furthermore, the tissues being treated can also exhibit both short- and long-term local changes that may produce tissue or tumoral edema, leading to other physical manifestations like increased intracranial pressure (ICP), seizures, and various neurological deficits. Although these potential complications are rare in patients who undergo several diagnostic procedures, they can become significant in patients who undergo repeated embolization procedures. In general, reducing and/or limiting the amount of radiation exposure to both the patient and the interventionist can avoid or minimize complications of radiation exposure. The importance of proper radiation shielding and reduction of radiation scatter cannot be stressed enough; this reduction can be accomplished by several maneuvers, including moving the radiation source closer to the patient, reducing the number of frames per second, and avoiding unnecessary contrast injections.