1 Introduction to the Catheterization Laboratory

Cardiac catheterization is the insertion and passage of small plastic tubes (catheters) into arteries and veins to the heart to obtain x-ray pictures (angiography) of coronary arteries and cardiac chambers and to measure pressures in the heart (hemodynamics). The cardiac catheterization laboratory performs angiography to obtain images not only to diagnose coronary artery disease but also to look for diseases of the aorta and pulmonary and peripheral vessels. In addition to providing diagnostic information, the cardiac catheterization laboratory performs catheter-based interventions (e.g., angioplasty and stents, now called percutaneous coronary intervention [PCI]) or catheter-based treatments of structural heart disease for both acute and chronic cardiovascular illness. Table 1-1 lists procedures that can be performed with coronary angiography. Figure 1-1 shows common access routes for cardiac catheterization.

Table 1-1 Procedures That May Accompany Coronary Angiography ^∗

Procedure	Comment
1. Central venous access	Used as IV access for emergency medications (femoral, internal jugular, subclavian) or fluids, temporary pacemaker (pacemaker not mandatory for coronary angiography)
2. Hemodynamic assessment
a. Left heart pressures	Routine for all studies (aorta, left ventricle)
b. Right and left heart	Not routine for coronary artery disease; combined pressures; mandatory for valvular heart disease; routine for CHF, right ventricular dysfunction, pericardial diseases, cardiomyopathy, intracardiac shunts, congenital abnormalities
3. Left ventricular angiography	Routine for all studies; may be excluded with high-risk patients, left main coronary or aortic stenosis, severe CHF, renal failure
4. Internal mammary artery selective angiography	Not routine unless used as coronary bypass conduit
5. Pharmacologic studies
a. Intracoronary/intravenous/sublingual NTG	Routine for all coronary angiography
6. Aortography	Routine for aortic insufficiency, aortic dissection, aortic aneurysm, with or without aortic stenosis, routine to locate bypass grafts not visualized by selective angiography
7. Cardiac pacing and electrophysiologic studies	Arrhythmia evaluation
8. Interventional and special techniques	Coronary angioplasty (e.g., PTCA, stenting) Intracoronary flow-pressure for lesion assessment Balloon catheter valvuloplasty Myocardial biopsy Transseptal or direct left ventricular puncture Conduction tract catheter ablation
9. Arterial closure devices	Available for patients prone to access site bleeding

CHF, congestive heart failure; IV, intravenous; NTG, nitroglycerin; PTCA, percutaneous transluminal coronary angioplasty.

∗ See Table 1-2 for indications.

Figure 1-1 Vascular access routes for cardiac catheterization (also see Chapter 2). Radial and femoral arteries are the most common approaches.

Indications for Cardiac Catheterization

Cardiac catheterization is used to identify structural cardiac diseases such as atherosclerotic artery disease, abnormalities of heart muscle (infarction or cardiomyopathy), and valvular or congenital heart abnormalities. In adults the procedure is used most commonly to diagnose coronary artery disease. Other indications depend on the history, physical examination, electrocardiogram (ECG), cardiac stress test, echocardiographic results, and chest radiograph. Indications for cardiac catheterization are summarized in Table 1-2.

Table 1-2 Indications for Cardiac Catheterization

Indications	Procedures
1. Suspected or known coronary artery disease
a. New-onset angina	LV, COR
b. Unstable angina	LV, COR
c. Evaluation before a major surgical procedure	LV, COR
d. Silent ischemia	LV, COR, ±ERGO
e. Positive exercise tolerance test	LV, COR, ±ERGO
f. Atypical chest pain or coronary spasm	LV, COR, ±ERGO
2. Myocardial infarction
a. Unstable angina postinfarction	LV, COR
b. Failed thrombolysis	LV, COR, ±RH
c. Shock	LV, COR, RH
d. Mechanical complications (ventricular septal defect, rupture of wall or papillary muscle)	LV, COR, L+R
3. Sudden cardiovascular death	LV, COR, R + L
4. Valvular heart disease	LV, COR, R + L, ±AO
5. Congenital heart disease (before anticipated corrective surgery or ASD/PFO closure)	LV, COR, R + L, ±AO
6. Aortic dissection	AO, COR
7. Pericardial constriction or tamponade	LV, COR, R + L
8. Cardiomyopathy	LV, COR, R + L, ±BX
9. Initial and follow-up assessment for heart transplant	LV, COR, R + L, BX

AO, aortography; BX, endomyocardial biopsy; COR, coronary angiography; ERGO, ergonovine malate,; LV, left ventriculography; RH, right heart oxygen saturations and hemodynamics (e.g., placement of Swan-Ganz catheter); R + L, right and left heart hemodynamics; ±, optional.

Elective Procedures

For most patients, cardiac catheterization is performed as an elective diagnostic procedure. It should be deferred if the patient is not prepared either psychologically or physically.

Urgent Procedures

If the patient’s condition is unstable because of a suspected cardiac disorder, such as acute myocardial infarction, catheterization must proceed. In the event of decompensated congestive heart failure, rapid medical management is often needed. Although a patient must be able to lie flat for easy catheter passage, patients with acute cardiac decompensation may benefit more from aggressive management in the catheterization laboratory than from management in an intensive care unit. In the catheterization laboratory, intubation, intraaortic balloon pumping, and vasopressors can be instituted rapidly before angiography and a decision for revascularization.

Contraindications

Contraindications to cardiac catheterization include fever, anemia, electrolyte imbalance (especially hypokalemia predisposing to arrhythmias), and other systemic illnesses needing stabilization (Table 1-3).

Table 1-3 Contraindications to Cardiac Catheterization

Absolute Contraindications

Inadequate equipment or catheterization facility

Relative Contraindications

Acute gastrointestinal bleeding or anemia

Anticoagulation (or known, uncontrolled bleeding diathesis)

Electrolyte imbalance

Infection and fever

Medication intoxication (e.g., digitalis, phenothiazine)

Pregnancy

Recent cerebrovascular accident (<1 month)

Renal failure

Uncontrolled congestive heart failure, high blood pressure, arrhythmias

Uncooperative patient

Complications and Risks

For diagnostic catheterization, analysis of the complications in more than 200,000 patients indicated the incidence of risks as death, less than 0.2%; myocardial infarction, less than 0.05%; stroke, less than 0.07%; serious ventricular arrhythmia, less than 0.5%; and major vascular complications (thrombosis, bleeding requiring transfusion, or pseudoaneurysm), less than 1% (Table 1-4, Table 1-5). Vascular complications occurred more often when the brachial approach was used and least when the radial approach was used. Risks are increased in well-described subgroups (Table 1-6).

Table 1-4 Complications of Cardiac Catheterization

Major

Cerebrovascular accident

Death

Myocardial infarction

Ventricular tachycardia, fibrillation, or serious arrhythmia

Other

Aortic dissection

Cardiac perforation, tamponade

Congestive heart failure

Contrast reaction (anaphylaxis, nephrotoxicity)

Heart block, asystole

Hemorrhage (local, retroperitoneal, pelvic)

Infection

Protamine reaction

Supraventricular tachyarrhythmia, atrial fibrillation

Thrombosis, embolus, air embolus

Vascular injury, pseudoaneurysm

Vasovagal reaction

Table 1-5 Incidence of Major Complications of Diagnostic Catheterizations

	Number	Percent
Death	65	0.11
Myocardial infarction	30	0.05
Neurologic	41	0.07
Arrhythmia	229	0.38
Vascular	256	0.43
Contrast	223	0.37
Hemodynamic	158	0.26
Perforation	16	0.03
Other	166	0.28
Total (patients)	1184	1.98

Modified from Noto TJ, Johnson LW, Krone R, et al: Cardiac catheterization 1990: a report of the Registry of the Society for Cardiac Angiography and Interventions (SCA&I), Cath Cardiovasc Diagn 24:75-83, 1991; in Uretzky BF, Weinert HH: Cardiac catheterization: concepts, techniques, and applications, Walden, Mass, 1997, Blackwell Science.

Table 1-6 Conditions of Patients at Higher Risk for Complications of Catheterization ^∗

Acute myocardial infarction

Advanced age (>75 years)

Aortic aneurysm

Aortic stenosis

Congestive heart failure

Diabetes

Extensive three-vessel coronary artery disease

Left ventricular dysfunction (left ventricular ejection fraction <35%)

Obesity

Prior cerebrovascular accident

Renal insufficiency

Suspected or known left main coronary stenosis

Uncontrolled hypertension

Unstable angina

∗ See also Chapter 8.

Catheterization Laboratory Data

Information gathered during the cardiac catheterization can be divided into two categories: hemodynamic (see Chapter 3) and angiographic (see Chapter 4). The term cineangiography describes the x-ray photography of cardiac structures. Use of this term persists even though the images are now stored electronically on digital computer imaging media (e.g., CD-ROM) rather than on cine film. The digital cineangiogram provides anatomic information about the chambers of the heart and the coronary arteries. Hemodynamic information is recorded from catheters inside the heart and consists of pressure measurements, cardiac outputs, and blood oxygen saturation measurements.

Preparation of the Patient

Consent for the Procedure

Consent is obtained by the operator or his or her assistant, usually a physician:

1. Explain in simple terms what procedure will take place and for what reason each step of the procedure will occur.

2. Explain the risks for routine cardiac catheterization. Major risks include stroke, myocardial infarction, and death. Minor risks include vascular injury, allergic reaction, bleeding, hematoma, and infection.

3. Explain any portions of the study used for research and the associated risks (e.g., electrophysiologic study—perforation, arrhythmia [<1:500]; pharmacologic study—varies depending on drug and study duration; intracoronary imaging or sensor-pressure wire study—spasm, myocardial infarction, embolus, dissection [<1:500]).

4. Provide the necessary information and explanation but do not overwhelm the patient. It is good practice to include the family when explaining what will happen and what possible outcomes you might expect.

There is no alternative to coronary angiography. Often the patient’s and family’s concern about “not knowing” about coronary disease necessitates performing the test.

The decision to undergo the procedure is always the patient’s. If the patient is reluctant to have the catheterization, the referring physician should be asked to speak to the patient to clarify why the procedure is necessary. A reluctant patient should never sign the consent. When possible, the family should be present when the procedure is discussed. This approach encourages a cooperative and generally sympathetic appreciation of the procedure and expected outcome.

Communication with Patients: A Nonmedical Person’s Understanding

The clinician establishes rapport and builds the patient’s confidence by listening and explaining. The procedure should be discussed with the patient in terms he or she can understand. The purpose of the procedure should be clear—“to look at the coronary arteries” and “to examine the heart muscle (ventricular function).” Simple terms are best so that the patient can grasp the concepts. The clinician should explain what small catheters are (plastic tubes similar in size to spaghetti) and that they will be used to put x-ray contrast dye into the arteries supplying blood to the heart. The heart muscle may be weakened (infarcted) in certain areas, and the way to identify this weakness is to take x-ray pictures. This example of a simple, forthright explanation facilitates the operator team-patient relationship so that confidence in the operator and team performing the procedure is established.

Laboratory Atmosphere: The Patient’s Confidence Builder

1. In the laboratory a confident, professional attitude should be assumed by all personnel at all times. Straightforward routine communication should occur quietly and without alarming tones. Patients should be addressed directly, by name, to let them know what their instructions are as opposed to requests or communications to co-workers.

2. The circulating team members should be confident, reassuring, and professional in every respect. The patient feels helpless and is tuned in to all types of stimuli (especially verbal).

3. Extraneous conversation is distracting for the patient and the operators. In the laboratory, all “players” should be in the game; that is, the patient’s needs and safety become paramount.

4. Communication with the patient (and family) before, during, and after the procedure ensures a satisfied and well-cared-for individual. Communication among the team members in a professional, courteous, and quiet tone builds patient confidences and helps the procedure go smoothly.

5. Factory worker attitudes of “another coronary” or “another transplant” should be avoided. Each procedure is potentially life threatening and should be undertaken seriously and with concern as if each patient were a family member.

6. Cardiac catheterization is stressful to the patient and the operator team. This stress should be minimized by thoughtful preparation and professional attention to detail.

7. Practical notes for the new operator include the following: Immediately before the catheterization in the laboratory, reexamination of the ECG is essential. A brief reiteration of the history ensures that no interval change has occurred since the last interview. A brief examination of the patient—checking heart sounds, breath sounds, and carotid and peripheral pulses—is also essential immediately before and after cardiac catheterization. No patient should be studied without full understanding of the clinical conditions and results of previous catheterizations and other pertinent laboratory data.

When on the catheterization table, the patient remembers two major potentially painful points of a case: (1) the initial introduction of the local anesthetic (and sometimes radial sheath introduction) and (2) any discomfort experienced after the study has been completed. Such discomfort usually occurs while the operator or nurse is holding the femoral puncture site. If the local anesthetic injection is performed too quickly or the arterial closure-compression after the procedure is difficult or painful, the patient will remember that the physician who performed the catheterization “hurt me.” The period between the two events is often forgotten (thanks to premedication). These two points should be kept in mind as the major “take-home” messages. Patients cannot discern the operator’s skill or level of accomplishment during the procedure, but they judge the operator (and the team) on the manner and care at the beginning and end of the study. Skill and accomplishment during the procedure are essential, but these are developed during the operator’s training period.

8. General catheterization orders: Before catheterization, preferably the preceding night, precatheterization orders should be written. All medications and procedural premedications should be tailored to the patient and timing of the catheterization. If the patient is using long-acting insulin (neutral protamine Hagedorn [NPH]), the dose should be reduced 50% and the patient should not eat breakfast. The patient should be watched carefully for hypoglycemic reactions (e.g., shaking, confusion, slurred speech).

9. Patients should wear their glasses and dentures in the laboratory to make communication easier.

In-Laboratory Preparations and the “Time-Out”

The staff of the cardiac catheterization laboratory is responsible for patient preparation before the start of the procedure. On the patient’s arrival in the laboratory, a staff member should review a brief checklist to ensure that all preprocedural requirements have been met. A sample checklist follows:

• Check the patient’s ID band, known allergies.

• Check laboratory results (key tests: blood urea nitrogen, creatinine, prothrombin time, partial thromboplastin time, electrolytes).

• Check blood pressure, all pulses (arms and legs), baseline ECG.

• Anticoagulant status. Check the international normalized ratio (INR) and partial thromboplastin time (PTT) and if on heparin, the activated clotting time (ACT).

• Check childbearing potential (may need β-human chorionic gonadotropin level).

• Assess the patient’s understanding of the procedure and answer the patient’s questions.

• Verify that the proper paperwork has been copied and filled out for the procedure. Check that the consents and oral airway forms for the procedure are signed and in the chart. If not, make arrangements for their completion before the procedure.

• Check that the intravenous (IV) line is patent.

• Check that the patient has ingested nothing by mouth before the procedure.

• Check whether premedications were given as ordered.

• Start document of the precatheterization condition, and note any physical deficits (abnormal neurologic examination, bruising or bleeding sites).

After all precatheterization requirements have been fulfilled, the patient may be taken to the angiographic suite and the technical preparations can be completed.

Catheterization Suite Preparations

Before the start of the catheterization procedure, the staff performs the following tasks:

1. Establishes ECG monitoring. The ECG should be considered first of the two major “lifelines.” The heartbeat is monitored for rate and rhythm during the entire procedure. It is the responsibility of the staff to place the electrodes and lead wires in such a fashion that a quality trace is obtained. Care must be taken that the electrodes and lead wires do not interfere with the movement of the x-ray and cineangiographic unit. All leads should be secure, and a good signal should be present before the application of sterile drapes; reaching under the sterile drapes to reattach loose lead wires once the procedure has begun is difficult. Radiolucent leads permit complete 12-lead ECG monitoring but are more prone to breakage than heavier cable leads.

2. Establishes IV access for emergency medications or sedation. The second lifeline is the IV access. Without good IV access, emergency drugs to counteract vagal or allergic reactions cannot be effective. In most cases the patient is given an oral sedative as premedication before arriving at the cardiac catheterization laboratory. When the patient is in the laboratory, the nurse or physician may identify the need for additional sedation or analgesia before the start of the procedure. The IV line is also important for hydration after cardiac catheterization.

Caution must be exercised when premedicating elderly patients. If meperidine (Demerol), fentanyl, or morphine is used, a narcotic antagonist such as naloxone (Narcan) should be available. Flumazenil (a benzodiazepine antagonist) should also be available if diazepam (Valium) or midazolam (Versed) is used.

The “Time Out”

In any active catheterization laboratory, preparations can be hectic, perhaps even frantic at times. This frenetic pace can cause problems, important steps can be missed, and patient safety can be compromised. Time out is a Joint Commission requirement. It was originally designed for surgical procedures that required an accurate identification of the patient, procedure, site, and side. It is a critical safety check to eliminate the mistake of operating on the wrong patient or wrong site.

Sterile Preparations

Cardiac catheterization is performed using aseptic technique in an operating room setting with personnel in scrubs, protective hats, masks, and gowns.

Vascular Access Site Preparation

The most common vascular access sites are the right groin for the femoral approach or the right wrist for the radial artery approach. Of course, the left-side arteries are available as well when needed. The usual sterile preparation begins by clipping the area of hair and vigorously applying an antiseptic solution. Shaving should be avoided because of microlacerations or abrasions breaking the skin barrier to infection.

During patient preparation the staff should always be aware of the patient’s need for privacy. The patient should be kept covered as much as possible. Procedure rooms are typically cold; every effort should be made to keep the patient warm and comfortable.

Sterile Field Preparation and Patient Draping

A staff member assigned to assist the physician in the procedure puts on hair and shoe covers and surgical face mask and washes the hands and forearms as a surgical scrub. He or she then puts on a sterile surgical gown and gloves. An equipment stand is prepared in a sterile fashion to hold all the catheters and other equipment to be used during the procedure. At this time, a circulating staff member hands catheters and necessary equipment not included in the sterile catheter laboratory pack to the scrub nurse or technician. A sterile drape is placed over the patient, starting at the patient’s upper chest and extending to the foot, covering the entire examination table.

It is important for all personnel to understand sterile techniques to avoid accidentally contaminating any sterile fields. As a basic rule, no unsterile object may be passed over a sterile field. A sterile gown and gloves rather than gloves alone should be worn when preparing the back table and patient, especially for team members who are very short or wide and whose body may accidentally contact the sterile areas. When moving around a crowded angiographic room, all personnel should be careful to avoid bumping into or passing hands or arms over the sterile tray, table, or patient drapes. Personnel should not walk between the sterile table or equipment tray and the patient. Touching the ends of any catheters, extension tubes, or syringe tips in a sterile field or the power injector syringe tip that is exposed should be avoided.

Rules for Observers in the Laboratory

Some hospitals have policies that limit nonhospital personnel from being in the catheterization laboratory without prior consent of the patient. Any observers in the angiographic room should respect the professional atmosphere and keep extraneous conversation to a minimum. Observers should wear a lead apron as protection against scattered radiation. Usually it is unnecessary for observers to wear gowns. Observers should avoid sterile fields and should be aware of the precautions necessary for protection from blood and body fluids.

No one but catheterization laboratory personnel should ever manipulate or adjust any device, equipment, or medication system in the laboratory. To prevent observers who are not laboratory personnel from becoming overly enthusiastic and attempting to assist the nurses or physicians, they should never be given sterile gloves. This is an important potential liability issue for the laboratory, hospital, and staff.

Conscious Sedation for Invasive Cardiac Procedure

The purpose of conscious sedation is to relieve patient anxiety, discomfort, or pain associated with the procedure. The following criteria define conscious sedation:

1. The patient at no time loses protective reflexes.

2. The patient retains the ability to maintain an open airway continuously without help.

3. The patient responds appropriately to verbal and physical stimulation.

When the patient can no longer do the things listed, the sedative technique has evolved to deep sedation or general anesthesia. At this point the monitoring and care of the patient must be elevated to avoid an adverse outcome.

A conscious sedation protocol has four major components: (1) preprocedural baseline assessment, (2) drug dosage and administration, (3) patient monitoring, and (4) postprocedure monitoring and assessment and discharge criteria.

Preprocedural Assessment

Before the administration of sedative agents, the patient should have a complete assessment of his or her current physical condition. The clinician should pay particular attention to any preexisting conditions that would put the patient at risk for an adverse outcome if sedatives are administered. A preprocedural evaluation should include a review of the major organ systems, the time and type of the last oral intake, a history of drug and alcohol use, a history of smoking, and a history of previous experience with sedative agents.

Preprocedural fasting is the rule. Sedative agents may impair airway reflexes, placing the patient at increased risk for aspirating gastric contents. For elective procedures these risks can be minimized by allowing sufficient time for gastric emptying before the procedure. The patient should be NPO for solids and nonclear liquids after midnight or at least 8 hours before the start of the procedure. Clear liquids may be appropriate 1 to 3 hours before the procedure, depending on the type and dose of the sedative agent to be used.

Physical Examination and Airway Assessment

An airway assessment should be part of the preprocedural routine. Most preprocedural check lists included the Mallampati classification (see Appendix I), which is used to predict the ease of intubation. Mallampati scoring is as follows:

A high Mallampati score (class 4) is associated with more difficult intubation, as well as a higher incidence of sleep apnea. Factors associated with difficult airway management also include the following:

1. A history of sleep apnea, snoring, or stridor

2. Dysmorphic jaw or facial features

3. Advanced rheumatoid arthritis

4. A short neck with limited extension caused by obesity, mass, or injury

5. Mouth or jaw irregularities or deformities, including loose or capped teeth or dentures

American Society of Anesthesiologists Physical Status Classification

The American Society of Anesthesiologists Physical Status Classification (Table 1-7) is helpful in determining the patient’s eligibility for conscious sedation. It uses a 1 to 5 classification range, with 1 being a healthy patient and 5 being a moribund patient. Procedural sedation is appropriate for patients in Classes 1, 2, and 3. Patients in classes 4 and higher are better suited for general anesthesia. There are several contraindications to conscious sedation (CS) that include the following:

1. Recent (<2 hour) ingestion of large food or fluid volumes

2. Physical class 4 or greater

3. Lack of support staff or monitoring equipment

4. Lack of experience/credentialing on part of clinician

Table 1-7 American Society of Anesthesiologists Physical Status Classification

Class	Description
1	A healthy patient (e.g., varicose veins in an otherwise healthy patient)
2	A patient with mild systemic disease that in no way interferes with normal activity (e.g., controlled hypertension, controlled diabetes, chronic bronchitis)
3	A patient with severe systemic disease that is not incapacitating (e.g., insulin-dependent diabetes, angina, pulmonary insufficiency)
4	A patient with severe systemic disease that is a constant threat to life (e.g., cardiac failure, major organ insufficiency)
5	A moribund patient who is not expected to survive for 24 hours with or without surgery (e.g., intracranial hemorrhage in coma)

Monitoring Parameters

Level of Consciousness

The patient’s level of consciousness should be assessed often before and during the procedure. The level of consciousness can be assessed by the patient’s response to verbal commands or to light tactile stimulation. Once aroused, the patient should respond appropriately to verbal commands. The nurse or operator can assess this easily by periodically talking to the patient and listening to his or her response. When the patient’s only response is reflex withdrawal from painful stimuli, deep sedation is evident, and special care must be taken to ensure patency of the airway, proper ventilation, and hemodynamic stability.

Pulmonary Ventilation

Pulmonary ventilation can be monitored by the observation of spontaneous respiratory activity or, when possible, auscultation of breath sounds. During certain invasive procedures, direct monitoring of the respiratory rate is often difficult because of sterile drapes and equipment.

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Introduction to the Catheterization Laboratory