Introduction

. . . an 82-year-old woman was admitted with a cold, pulseless, continuously painful left lower extremity with an associated 2 by 4 cm. ischemic ulcer and progressing gangrene of three toes. . .

Because of advancing gangrene, amputation was strongly advised but the patient refused. On January 16, 1964, percutaneous transfemoral catheter dilatation was carried out in a matter of minutes and without difficulty. Coincident with removal of the catheter from the site of previous stenosis, good pulses were palpable for the first time in the lower leg and foot . . . pain, discoloration, and coldness of the foot, present on admission, diminished immediately. There was rapid healing of the ischemic skin changes, including ulceration of the lower leg.

- Charles T. Dotter, M.D.

In 1964, Charles T. Dotter published his description of a new technique, Transluminal Treatment of Atherosclerotic Obstruction, in the journal Circulation. While this landmark publication heralded a new era in the treatment of vascular disease, Charles Dotter and other angiographers of the time laid the foundation for new and revolutionary treatment options in many diseases. These enormous contributions culminated in the creation of a new medical subspecialty: Vascular and Interventional Radiology.

Vascular and Interventional Radiology, also called "Special Procedures" is the surgical sub-specialty of radiology devoted to invasive diagnostic and therapeutic procedures in the vascular and various other organ systems. Training in Vascular and Interventional Radiology requires a 1 to 2 year fellowship following residency in diagnostic radiology. Vascular and Interventional Radiology is an accredited subspecialty with examination and certification by the American Board of Radiology.

Most procedures in Vascular and Interventional Radiology are performed through catheters. Consequently, special competence in catheter and guide wire manipulation, and a thorough knowledge of both the available tools and equipment, and the anatomy and pathophysiology of multiple organ systems and their disease processes are essential to the successful performance of these techniques.

This syllabus is intended as an overview of Vascular and Interventional Radiology for medical students, radiology house staff, and the residents and staff of the various services referring patients for invasive radiological procedures. Following review of this manuscript, the reader should have a basic knowledge of the types of procedures offered by interventional radiologists, and should be able to integrate that knowledge into a rational diagnostic or therapeutic care plan in appropriate clinical settings.

Patient Preparation and Management

Referrals and Consultations

Procedures performed in Vascular and Interventional Radiology differ significantly from those in general diagnostic radiology, both in their invasiveness, and in the fact that these "tests" must be performed by physicians rather than ancillary personnel. Because of their invasive nature, these diagnostic and interventional procedures must be tailored to answer specific questions or achieve a specific result. Shotgun approaches are inappropriate as they subject the patient to unnecessary discomfort and increased risk from various factors including radiation and contrast media exposure. Procedures should only be requested if results potentially would alter the patient's care. Academic interest alone is an inadequate indication for invasive procedures. Consequently, consultation between the referring physician and interventional radiologist is mandatory in order to assure that the requested procedure is appropriate and properly planned. Simply ordering a procedure without consultation will inevitably result in scheduling delays.

The referring physician should be aware of a variety of patient factors that may result in cancellation of a scheduled procedure. Surprisingly, one of the most common and frustrating problems leading to cancellation of a scheduled procedure is poor communication between the referring physician and patient. All too often patients simply refuse to give consent because they are not aware of the planned procedure and have not discussed it with their doctor. This is inexcusable, entirely preventable, and more than a mere inconvenience. It is a problem that often results in delaying or postponing procedures scheduled for other patients, and it is responsible for a significant waste of hospital resources.

All patients for invasive or contrast enhanced procedures must be on clear liquids or NPO for minimum of 6 hours. Patients who have eaten within that time period will be rescheduled. Nearly all procedures in interventional radiology require the use of contrast media. Patients scheduled for such procedures must be questioned about previous adverse reactions to iodinated contrast. A positive history of contrast reaction will necessitate a minimum 12 hour course of premedication with corticosteroids. Patients who have had severe reactions may require anesthesia standby.

Referring physicians should also be aware that an uncorrected coagulopathy is an absolute contraindication for most vascular and interventional procedures. Recent laboratory values for PT, PTT, and platelets must be available and abnormalities must be corrected prior to the procedure. Coumadin should be stopped 2 days and heparin 4-6 hours prior to a procedure. Normalization of laboratory values should be confirmed before the patient is transported to the department. Generally, procedures performed in the venous system are an exception to this rule. All patients should be well hydrated, especially those with marginal renal function. In severe renal insufficiency a nephrology consultation should be obtained.

Patients having a No Code Blue or Do Not Resuscitate status will not be considered for those invasive procedures capable of precipitating a fatal event. It is clearly unreasonable to request a physician to perform a procedure that could induce hypotension, bradycardia, or a potentially lethal arrhythmia, while denying him the opportunity to manage such a complication. Therefore, if the procedure is to be performed, the patient will have to consent to modification of the No Code or DNR orders, and such change in status must be documented in the patient's chart. Unlike DNR orders, Advance Directives would not prohibit treatment of procedure related complications in most cases. Nevertheless, this issue should be discussed with the patient and clarified in the medical record.

Finally, some patients are physically unable to undergo procedures in interventional radiology. Fluoroscopy tables have weight limitations on the order of 300 to 350 pounds (135-160kg). Larger patients cannot be accommodated. Very obese patients of short stature who do not exceed the table weight limit may not be candidates for certain procedures requiring fine catheter manipulations because of the inability of fluoroscopy to adequately penetrate in such individuals. Scoliosis, contractures, surgical wounds, orthopnea and other physical and/or mental impairment may render the intended procedure impossible, or possible only with general anesthesia. It behooves the referring physician to make a thorough assessment of the patient and communicate any such potential problems to the interventional radiologist at the time of consultation. Quite often an alternative procedure or technique can be suggested.

Pre-Procedure Evaluation

Prior to any invasive radiological procedure the patient will be evaluated by a member of the interventional radiology team. A brief history and physical examination will be performed, any questions the patient may have regarding the procedure will be answered, and consent for the procedure will be obtained. Inpatients scheduled more than 24 hours in advance will be seen the evening prior to the procedure. Pre-procedure orders for these patients will usually include a mild sedative at bedtime. Inpatients scheduled as same day add-ons will usually be seen within an hour of the consultation, and emergency patients will be seen immediately or evaluated on arrival to the department. Outpatients are evaluated in the department prior to the procedure. Outpatients scheduled more than 24 hours in advance will also be contacted by telephone the day or evening prior to the procedure to confirm the appointment, review diet and medication instructions, and answer any questions.

Premedication

Routine pre-procedure medications for inpatients include atropine, 0.4mg IV or IM, and Ativan, 1mg IV or PO on call to radiology. Patients with a history of contrast reactions are pre-treated with hydrocortisone or methylprednisilone, and Benedryl. All contrast reaction prophylaxis protocols require a minimum of 12 hours to complete, and must begin at least 13 hours before the procedure. Consequently, when the need for prophylaxis is uncovered on the day of the procedure, the patient must be rescheduled and will usually receive up to 24 hours of prophylaxis. All patients will receive an additional 100mg dose of hydrocortisone at the start of their procedure. Emergency procedures in patients with a known history of contrast reactions will require anesthesia standby. These patients will generally receive a large intravenous bolus of glucocorticoid. However, there is little evidence that less than 12 hours of pretreatment is protective.

Patients referred for GU and biliary interventions require broad spectrum antibiotic coverage. Ideally, antibiotics should be started at least 12 hours before the procedure. Ancef, 1gm IV q6h with a dose on call to radiology is usually sufficient although, for patients with calculus disease, the addition of an aminoglycoside such as gentamicin 80-100mg IV on call is recommended.

With the exception of aspirin and coumadin, patients should continue their regular medications on the day of the procedure unless instructed to do otherwise. Diabetic patients will have blood glucose monitored during the procedure, and glucose-containing intravenous fluids will be used as required. Patients referred for renal angioplasty should have their antihypertensive medications withheld the morning of the procedure. These medications can be restarted following the procedure. However, dosages will usually need to be adjusted following successful angioplasty.

Patient Sedation and Monitoring

Nearly all of the procedures in Vascular and Interventional Radiology entail some discomfort and engender some degree of anxiety in the patient. Therefore, most procedures are done using conscious sedation. Currently, Fentanyl and Versed are the drugs of choice for conscious sedation during invasive radiological procedures. Fentanyl is a potent synthetic narcotic that produces excellent analgesia. Versed is a benzodiazepine with sedative, anxiolytic, and amnestic effects. The two drugs appear to act in synergy. Following intravenous injection, both of these drugs have a rapid onset of action and are relatively short acting. Thus, dosages can be titrated during the procedure and recovery is relatively rapid. These drugs produce a minimum of cardiovascular side effects in most patients, and effective antagonists are available for both. Respiratory depression is the most common untoward effect of conscious sedation using these drugs. Therefore, all patients receive one-on-one nursing care during their procedures with monitoring by continuous EKG, noninvasive automated blood pressure measurements, and pulse oximetry. Monitoring continues during a post procedure recovery period of 30 minutes to several hours, depending on the procedure performed

Post-Procedure Management

The requirements for post procedure care vary greatly with the nature of the procedure performed. For inpatient procedures, detailed orders will be posted in the patients hospital chart. Outpatients will receive instructions and teaching prior to discharge from the department. Depending on the procedure performed, some outpatients will also have follow-up by telephone the day following the procedure.