Preparation of the patient for diagnostic catheterization
Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
A thorough history and physical examination should be obtained prior to cardiac catheterization. Based upon Appropriate Use Criteria, the indications for cardiac catheterization and coronary angiography should be carefully documented in the medical record. A thorough history should be obtained regarding prior development of an allergic reaction following iodinated contrast administration or shellfish ingestion. Preoperative medications should be carefully documented. Among diabetic patients, Neutral Protamine Hydrolase (NPH) insulin can cause hypotension when administered with protamine and metformin administration along with iodinated contrast administration can cause severe lactic acidosis.
A thorough history is essential in the patient who is to undergo cardiac catheterization. The following issues deserve particular attention:
Known congenital heart disease:
Care should be taken to be aware of left to right shunts. Note the presence of dextrocardia or situs inversus so that reversed anatomy can be anticipated.
History of shellfish allergies and contrast reactions:
Both the presence and the nature of these should be carefully noted. If the patient did have a prior contrast reaction, the severity of the reaction should be noted in order to gauge the risk of the current procedure. Signs and symptoms of a contrast reaction include the following:
- Stridor or respiratory compromise
- Anaphylactic shock
If the patient has a history of contrast reactions, they should be pre-medicated with Benadryl (diphenhydramine) 50 mg, Cimetidine (or an alternative H2 blocker) and steroids. In patients with a history of serious contrast reactions, a small puff should be done prior to angiography to ascertain if even this small injection triggers an amnestic response. Throughout the procedure, the nurse should check the patient for emergence of a rash and for any symptoms of breathing difficulty.
History of Allergy to Aspirin
- Note any history of nasal polyps and allergy to aspirin and any prior attempts at aspirin desensitization.
The presence of diabetes may increase the risk of the following:
- Contrast nephropathy. Diabetes, age over 65, and prior dye load within the past 24 hours are risk factors for the development of post procedure renal insuffiency.
- Vascular complications.
- Protamine is widely used for reversing systemic heparinization after cardiac catheterization. Although rare, major reactions to protamine that simulate anaphylaxis occasionally occur. Because neutral protamine Hagedorn (NPH) insulin includes protamine, it might be anticipated that NPH insulin-dependent some diabetic patients have a sensitivity to protamine. Of 866 consecutive patients undergoing cardiac catheterization over a 20 month period, 651 received protamine for reversal of heparinization. Of these, 8.5% (56/651) were diabetics and 2.3% (15/651) were NPH insulin-dependent diabetics. During this period seven patients were observed immediately after administration of protamine to have major adverse reactions that required the administration of catecholamines. One death ensued. Of the seven major reactions, four occurred in NPH insulin-dependent diabetics and one occurred in a patient with an allergy to fish. The incidence of major protamine reactions was 27% (4/15) in the NPH insulin-dependent diabetics vs 0.5% (3/636) in those with no history of NPH insulin use (p less than .001). This represents a 50-fold increased risk of a major reaction to protamine if the patient was receiving NPH insulin. Accordingly, we recommend that diabetics on NPH insulin and patients with allergies to fish undergo cardiac catheterization without the use of protamine or, when necessary, that protamine be administered cautiously in anticipation of a major adverse reaction. #1
The following tests should be reviewed before coronary arteriography:
- Electrolyte tests
- Renal function tests
- Complete blood cell count: The presence of thrombocytopenia would be a contraindication to the administration of parenteral glycoprotein 2b3a inhibitors. The platelet count should be documented prior to the administration of unfractionated heparin, low molecular weight heparinoids, and parenteral glycoprotein 2b3a inhibitors as all 3 classes of agents can be associated with the development of thrombocytopenia. In the case of UFH and LMWH this syndrome is called Heparin Induced Thrombocytopenia (HIT),
- Coagulation panel: An INR > 2.0 is a relative contraindication for cardiac catheterization.
An electrocardiogram should be obtained for the following reasons:
- Document the presence or absence of baseline ischemic findings prior to cardiac catheterization. Ischemic changes would suggest the presence of an acute coronary syndrome which would be an indication for percutaneous coronary intervention (PCI).
- The presence of a bundle branch block. Cardiac catheterization can result in dmage to the HIS system and a new bundle branch block, and the operator should be prepared for this prior to the procedure.
- Aspirin: Patients who may undergo PCI should receive aspirin, 162 to 325mg, at least 2 hours before the procedure if PCI is planned.
- Warfarin should be discontinued 2 days before elective coronary arteriography, and the INR should be less than 1.8 before arterial puncture.
- Unfractionated heparin or subcutaneous low-molecular-weight heparin: Patients at increased risk for systemic thromboembolism on withdrawal of warfarin, such as those with atrial fibrillation, mitral valve disease, or a prior history of systemic thromboembolism.
- PMID 6488493