A cardiologist from North Carolina wrote a query that said, “One of my colleagues had a patient with a stroke following a left ventriculogram. What happened afterwards was described as a Chinese fire drill with lots of people running around, but not much action.” He continues, “In researching the subject, there was a lack of consensus on how management of post cath stroke should be handled. Although there are five neurologists at our hospital, there is no uniformity of opinion as to what to do. Are there any guidelines dealing with this rare but potentially treatable event? Is there a national consensus or specialty society recommendation that you are aware of?”
Fortunately, stroke is a truly rare event. Unfortunately, I know of no formal guidelines addressing stroke in the cath lab. One of the best reviews I found recently is in The Journal of Invasive Cardiology by Dr. R. Sankaranarayanan and colleagues, “A Review: Stroke complicating cardiac catheterization and preventable and treatable complication,” January 2007, who discuss the diagnosis and treatment for stroke in the lab.(1) I summarize their findings and add some personal notes below.
How often does stroke occur in the cath lab?
This rare complication is reported for diagnostic procedures occurring from 0.03% to 0.3%, and for percutaneous interventions up to 0.4%. When discussing risk of stroke with patients prior to the diagnostic procedure, I indicate approximately 1 in 1,000 patients may suffer this complication, usually related to significance of underlying co-morbid conditions such as vascular disease.
What are the predisposing factors to stroke?
Older patients with old arteries, i.e. more atherosclerotic disease, are particularly prone to vessel trauma with release of fragments. Multiple large or stiff guidewires and catheters may cause fragmentation of atherosclerotic plaque, produce a cholesterol embolus, or promote thrombus formation at a catheter tip. Additional risk factors include female gender, left ventricular hypertrophy, hypertension, diabetes, renal insufficiency, and prior stroke. Patients with advanced coronary artery disease, prior bypass graft surgery, and extensive aortic plaque on transesophageal echo are likewise at increased risk. A stroke after ventriculography may occur in patients with depressed ejection fraction possibly due to increased likelihood of left ventricular thrombus. Certain types of intravascular equipment, such as large-caliber guide catheters, especially the left Judkins and multi-purpose guiding catheters, have been shown to be associated with dislodged atherosclerotic debris from the aorta. Interestingly, prolonged procedure times (often an indicator of a difficult catheter manipulation) are associated with stroke in the lab. Recall that it is always important to aspirate catheters after positioning to clear any materials that may have collected in the catheter during advancement up the aorta. Gaseous emboli caused by micro bubbles can occur after rapid withdrawal of balloon catheters from the guide catheter by creating a vacuum and having air enter the Y connector. The next flush or injection causes an air embolus. Radial artery access has higher incidence of stroke than femoral artery access, most likely due to passage of catheters and guidewires across the vertebral and carotid systems. The strongest clinical predictors of atherosclerotic aortic debris are advanced age and peripheral vascular disease. Older patients with peripheral vascular disease (PVD) are at risk no matter what access you choose, but careful consideration of the arm versus the leg approach is needed.
Clinical features of stroke following coronary angiography
Strokes occur during the procedure or shortly thereafter, often while the femoral sheath is still in place. Some patients have a delayed presentation up to 36 hours later. The symptoms include visual disturbance, motor weakness, aphasia and altered mental status. In a large review of 6,500 patients, the most common symptoms were visual disturbance in a quarter, hemiparesis in a quarter, and facial droop in a quarter, and miscellaneous neurologic deficits in the remaining individuals. The outcome of stroke after cardiac cath varies with the Rankin score, a measure of disability from minimal to coma, with high scores associated with high inpatient mortality.
What to do after a stroke in the cath lab?
1. Stabilize the patient. Maintain hemodynamic and arrhythmia control.
2. Contact neurology.
3. Plan on imaging investigations such as computed tomography (CT), magnetic resonance imaging (MRI) or both. Contrast resolution of MRI is significantly higher than that of CT, making it more sensitive for cerebral ischemia. More than any other method, diffusion-weighted MRI is sensitive for ischemia. Defects on diffusion-weighted MRI may not always translate into clinical deficits; however, this is the best marker of stroke after cath.
4. If advised by neurology, cerebral angiography is a quick and sensitive way to determine which vessel may be involved and define the presence of a thrombus for direct treatment using thrombolytic therapy. Angiography can be performed by a skilled cardiologist accompanied by a neuroradiologist in the cath lab.
Treatment for stroke in a cath lab: thrombolysis?
The treatment depends on degree of neurologic impairment and the mechanism (acute thrombus vs. cholesterol or air embolus). In myocardial infarction, vessel occlusion occurs from platelet-rich thrombi forming on atherosclerotic plaque. However, ischemic strokes’ thrombotic emboli, formed in proximal extracranial arteries or in the heart (inside or from catheters), respond differently to thrombolytics. The volume of clot in ischemic stroke is greater than that seen in myocardial infarction. Thrombolysis for acute ischemic stroke has been favorably received, but it is a source of controversy and debate. The National Institute of Neurological Disorders and Stroke trial using intravenous TPA in 1995 established the treatment for spontaneous acute stroke of less than 3 hours. However, no standards for acute therapeutic options exist in the cardiac cath lab nor have any standards been developed. Although there are many studies using thrombolysis for acute stroke, those applying to cardiac catheterization are limited. Segal et al reports the outcome of untreated stroke complicating cardiac catheterization is poor.(2) Like acute myocardial infarction, the management of stroke is the reestablishment of blood flow through recanalization by all appropriate means. Intra-arterial thrombolysis via catheter has been used, but appropriate intravenous thrombolysis appears to be better suited for smaller distal emboli as opposed to large intracranial vessels. Recanalization rates can be expected between 70% and 31% for intra-arterial versus intravenous thrombolysis, respectively.(3) Advantages of intra-arterial thrombolysis include direct infusion to the site of occlusion, lower systemic concentration of thrombolytics, less risk of extracranial hemorrhage, and better delineation of arterial anatomy, collateral circulation and the potential use of mechanical means for thrombo-aspiration. Disadvantages of intra-arterial approach are the time required for angiography and necessary experience for infusion catheter placement.
Although stroke is a rare event, we should all continue to pay attention to our patient throughout the procedure. Although I personally like a quiet, comfortable, nearly sleeping patient who does not want to chat, I do frequently ask the patient how he or she feels to gauge his or her ability to speak and respond. It is important to know if something has happened after each step of your cath procedure. Should a new neurologic deficit appear, diagnosis and treatment should be promptly instituted. Complete the procedure and then consult neurology. Since the event occurred in the laboratory, there is an opportunity to institute rapid neurovascular rescue through catheter-based reperfusion techniques, if appropriate personnel and equipment are available. Keep in mind that the optimal reperfusion strategy has yet to be defined. The cath lab staff and cardiologists performing catheterization should be checking the patient carefully before and after cath, and acquaint themselves with a friendly neurology consultant (in advance) who can help should stroke be suspected.