CHAPTER 4
Precatheterization Care
“Diligence is the mother of good fortune.”
—Benjamin Disraeli
The Rule of the Rules
A meticulous preprocedural work-up keeps major and minor complications of cardiac catheterization at a minimum.1,2 First, the referring physician provides the indication for the type of invasive procedure requested and is available for questions. Second, the invasive cardiologist performing the procedure has a solid knowledge base of (1) general indications and contraindications of the requested procedure, (2) methods of controlling pre- and postprocedural risk factors, and (3) types of possible procedural difficulties and complications and how to handle these. Third, the operator follows the unwritten rule that time spent examining and evaluating a patient, studying the paper chart or electronic medical record, reviewing previous coronary angiography images and pressure tracings (Box), and documenting findings is rewarded by procedural safety and patient satisfaction.
An invasive cardiologist should never hesitate to:
- Postpone an elective procedure if important data are missing during the preprocedural assessment.
- Ask for advice or help from a colleague when needed at any step of the procedure.
- Cancel the procedure if it is not indicated, and discuss the case with the referring physicians.
The standard set of laboratory data—complete blood count (CBC), serum electrolytes, serum creatinine, and anticoagulation parameters (PT/PTT/INR)—should be obtained, reviewed, and corrected if possible. All patients should have a solid, secure, 21-gauge intravenous access and preprocedure ECG. Patients with diabetes mellitus on long-acting insulin therapy should administer half of the evening dose of insulin and hold the morning dose, with blood glucose levels frequently monitored and appropriately controlled with short-acting insulin. Oral hypoglycemic medications should be placed on hold on the day of cardiac catheterization until feeding is resumed postprocedure. It is recommended to hydrate patients 4–6 hours pre- and 4–6 hours postprocedure with 0.45% or 0.9% normal saline. Also, patients should discontinue use of nonsteroidal anti-inflammatory drugs and, if possible, diuretics and ACE inhibitors on procedure day. It may be prudent to hold beta-blockers preprocedure in patients with previous history of anaphylactic reaction to contrast dye (in case epinephrine is needed to treat recurrent anaphylaxis). Antibiotic prophylaxis is not routinely indicated, but in rare cases when prophylaxis is considered, selection of the antibiotic agent should be based on its efficacy against the most common skin pathogens, and it should be given 30–60 minutes before the procedure. If fluoroquinolones or vancomycin is chosen, the agent should be given 2 hours before the procedure.
The Rules of Reading Coronary Angiography Images and Pressure Tracings
- 1.Note the artificial devices (pacemakers, wires, pacemaker/defibrillator leads, sternal wires, prosthetic valves) and amount of calcification (vascular, pericardial, valvular, annular) on cardiac fluorography.
- 2.Determine the catheter type and its French size to estimate the size of coronary vessels.
- 3.Determine the view:
- a.Find the spine: if on the left side of the screen, view is right anterior oblique (RAO); if on the right side of the screen, view is left anterior oblique (LAO); if in the middle, view is posterior anterior (PA).
- b.If spine is not visible, find the ascending portion of the catheter: if on the left side of the screen, view is RAO; if on the right side of the screen, view is LAO; if in the middle, view is PA.
- c.If spine and ascending portion of the catheter cannot be seen clearly, note the orientation of the ribs on the screen: if from left to right, view is RAO; if from right to left, view is LAO.
- d.If spine and ascending portion of the catheter cannot be seen clearly, look at the distal segment of the catheter: if the tip of the catheter crosses well over the ascending portion of the catheter, the view is RAO; if it comes near or just touches the ascending portion of the catheter, the view is PA; and if it is away from the ascending portion of the catheter, forming what can be described as “a wide-open fisherman’s hook,” the view is LAO.
- e.If the sternum is visualized on the extreme left of the screen, the view is left lateral.
- f.To determine cranial or caudal orientation of the view, look at the amount of diaphragm on the screen: if a significant portion of diaphragm can be seen at view initiation, this view has cranial angulation, and if not, it has caudal angulation. If this rule is not helpful, look at the vessels best seen on the view: when the left circumflex artery is coming down and is well outlined together with obtuse marginal branches without overlapping the other vessels, the view is with caudal angulation. On the contrary, when the left anterior descending artery and diagonals are well outlined and the left circumflex is directed up and not well visualized due to overlap, the view is with cranial angulation.
- g.In regard to right coronary, the view with cranial angulation gives the best visualization of the crux and the distal right coronary artery with posterior descending artery bifurcation. Caudal angulation rarely is used in routine diagnostic coronary angiography of the RCA.
- 4.When determining the severity of stenosis, assess all the views and compare them to an adjacent reference segment that is normal-appearing on angiography and to the catheter size. Eccentric stenosis may appear normal in one or two views. Review and describe the lesion: its complexity, presence of calcification, dissection, and thrombus. Comment on location and length of the lesion. Also comment on extent and pattern of luminal irregularities, dynamic changes of epicardial blood vessels caused by spasm, and myocardial bridging. Describe flow pattern and runoff of the contrast. Note source, destination, and magnitude of collaterals and presence of abnormal communications such as arteriovenous and arteriocameral fistulas.
- 5.Use available hemodynamic data in addition to angiographic data when judging the severity of ostial coronary stenosis.
- 6.Compare with previous angiographic studies if available.
- 7.Identify the cardiac rhythm, note recording speed and pressure scale, and time the pressure tracings based on simultaneous ECG strips.
- 8.Always interpret the hemodynamic waveforms in conjunction with the patient’s clinical presentation.
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