American College of Cardiology

The Pediatric Cardiac Catheterization Laboratory (PCCL) presents several challenges and differences not faced by the adult invasive cardiovascular specialist. The following is a general overview of these issues.

A. Differences in Goals

The PCCL should function as an element within a pediatric cardiovascular center or program. The overall goal of such a center or program should be to provide both comprehensive diagnostic services and a full range of treatments, interventions, and surgeries needed to provide high-quality pediatric cardiovascular care. Within the center or programmatic context, the goal of a PCCL is to perform a range of cardiac catheterizations in children with congenital or acquired heart disease and in adults with congenital heart disease. Unlike in adult cardiology, the usual case is that the heart internal structure is abnormal. Diagnostic catheterization may include quantitation of cardiac index, and calculations of left-to-right and right-to-left shunts and pulmonary vascular resistance are more often required. Right- and left-heart catheterization is the norm rather than the exception. Measurement of cardiac index by thermodilution is possible when there are no shunts, but measurement or assumption of oxygen consumption for Fick shunt determinations is more commonly performed. Because of periods of rapid growth in infancy and childhood and the need for comparison of data across sizes of patients or over time in the same person, output and resistance values are indexed or corrected for body surface area in pediatric cardiology. Furthermore, pediatric angiographic studies have goals that include defining and displaying intracardiac anatomy in a projection-type medium to complement the planar media of echocardiography and magnetic resonance or computerized tomographic imaging. A wide variety of congenital and acquired defects are investigated in the PCCL.

Pediatric interventional procedures are a primary or secondary objective in approximately half of all PCCL catheterizations. A wide range of unique interventional procedures is now possible. These procedures include balloon atrial septostomy, blade or balloon dilation atrial septostomy, valve and vessel dilation, stent implantation, patent ductus arteriosus and other vascular closure, endomyocardial biopsy, foreign-body retrieval, and the full range of electrophysiological procedures. Special expertise in pediatric patients is gained in these procedures during pediatric cardiology fellowship training and in pediatric cardiology postfellowship training in the interventional cardiac catheterization laboratory (often during an additional training year). PCCLs that routinely perform pediatric transcatheter interventional procedures should exist only in clinical environments where pediatric intensive care and pediatric cardiovascular surgery are available.

Sedation is an important function in the PCCL, where patients cannot be calmed or reassured without medication or even assumed to be able to remain on the procedure “bed.” The pediatric cardiologist assumes responsibility for the safe conscious sedation of the patient, and the importance of monitoring is no different from that described above for adults receiving sedation.

B. Who Should Perform Catheterization in Adult Congenital Heart Disease?

Pediatric cardiac catheterization laboratories, whether dedicated or shared with adult cardiologists, should have a pediatric director. The director should be board certified in pediatric cardiology and should have additional training in pediatric cardiac catheterization and intervention (or qualifying experience). The director should be responsible for all aspects of the administration and function of the PCCL (including backup of other pediatric operators with less training or experience). In addition, QA and QI activities related to pediatric studies should fall under the director's guidance.

Other than the PCCL director, attending physicians who perform cardiac catheterization in children are generally board eligible or board certified by the American Board of Pediatrics, Subspecialty Board of Cardiology. There may be exceptional cases in which a competent physician has gained extensive experience without formal board certification, but these physicians usually have been allowed privileges by a “grandparent” clause. Whether privileges for non-board-eligible physicians should be granted is left to the discretion of the individuals involved and the hospital credentialing process.

Although it is recognized that the definition of the “pediatric” age range is somewhat variable, it usually encompasses the period from birth through 18 (or 21) years of age. It is recommended that for patients under the age of 18 years who require cardiac catheterization for congenital cardiac problems, the procedure should be performed by a pediatric cardiologist. Adult patients with previously diagnosed (repaired or unrepaired) congenital heart disease or with native congenital heart problems requiring cardiac catheterization should have the procedure performed (1) by a pediatric cardiologist, (2) by an adult cardiologist and a pediatric cardiologist collaborating during the procedure (with one or both scrubbed), or (3) by an adult cardiologist with an established special interest and expertise in adult congenital heart disease. Adult cardiologists with little experience in congenital heart disease should not perform cardiac catheterization in patients with congenital cardiac problems.

C. Quality Assurance Issues

Representative complication rates for pediatric cardiac catheterizations are available from a number of reviews. A recent study of complications in 4952 consecutive pediatric catheterization procedures found an overall complication rate of 8.8%, with a major complication rate of 2.06% and a death rate of 0.14% ⁽¹²⁶⁾. A higher risk for complications was present in patients who were younger and in those undergoing interventional procedures. Fellows et al ⁽¹²⁷⁾, noted that the rate of complications for therapeutic catheter procedures depended primarily on the type of intervention. In that study, the rate of complications for aortic valve stenosis dilation was 10 times that for recurrent coarctation treatment. The Valvuloplasty and Angioplasty in Congenital Anomalies (VACA) study group ⁽¹²⁸⁾ reinforced this finding in 1990 in its series of articles concerning various types of interventional catheterizations. These complication rates might be expected to improve because of advances in catheter technology and techniques. However, the increasing percentage of interventional cases and postoperative catheterizations in smaller and smaller children may hold the complication rates at current levels. A center’s catheterization-related mortality should be <1%, and death should be extremely rare outside of neonatal and high-risk interventional cases. In addition, major complications (potentially life-threatening events) should occur in <2% of cases ⁽¹²⁶⁾. In radiofrequency ablation procedures, the incidence of permanent complete atrioventricular block should be 2% ⁽¹²⁹⁾.

Informed consent in the PCCL is usually obtained from the patient’s parents or guardians. This consent includes the physician's (or his or her designees, such as the cardiovascular fellows) explanation of the risks, benefits, and alternatives related to the procedure, with documentation of the explanation and of the parent/guardian understanding shown by a signature. In urgent or emergent cases, such as when a transferred patient requires emergency balloon septostomy and the parents are in transit, consent may be obtained by telephone or even assumed and the procedure performed. The Committee recognizes that there are consent and assent procedures and guidelines that vary by jurisdiction (hospital, state, county) and defers to those where applicable. Age or other circumstances that afford competence to the patient vary as well. These will determine whether it is acceptable to obtain the patient’s “assent” or whether formal consent is required.

D. Inpatient Versus Outpatient Setting for Procedures

Although outpatient procedures have become common in the PCCL, there is less uniformity in patient and parent suitability for hospital discharge shortly after catheterization than in adult patients. Infants and young children cannot be instructed or expected to remain still without moving their legs for a period after a procedure. Any volume of blood lost into the subcutaneous tissue or retroperitoneum or onto the bandage or bedclothes will have more significance if the patient is smaller. In general, patients and their parents may have to travel farther for treatment at a PCCL than at an adult catheterization laboratory. The patient may also be farther from appropriate medical attention after returning home. Despite the smaller size of the patient, the sheath sizes used in pediatrics may be nearly the same size (5F to 8F) as those used in adults. For these reasons, it is suggested that overnight observation be anticipated and allowed whenever there is any concern about patient safety.

Nonetheless, a set of written criteria should be established for same-day catheterization and discharge by each PCCL. These criteria would account for differences in procedure type, patient age and expected compliance, parent or guardian reliability, travel distance, procedure duration and time of completion, and the cardiac physiology in determining which patients are eligible for discharge on the day of catheterization. These guidelines should establish discharge criteria such as absence of bleeding, presence and adequacy of pulses and perfusion, access to medical evaluation and care after discharge, and parental understanding and ability to observe overnight.

E. Operator and Laboratory Volume

If a PCCL routinely performs <75 cardiac catheterizations per year, consideration should be given to whether the volume justifies the program. Although the Committee recognizes that access to services is important, there is also the valid impression that a minimum experience is required for the cardiologist and staff to maintain proficiency. In the previous ACC/AHA guidelines ⁽⁵⁾, the pediatric caseload for an individual was estimated at 50 to 100 cases per year. In the 1991 American Academy of Pediatrics guidelines ⁽¹³⁰⁾, it is recommended that a minimum of 1 to 2 catheterizations be performed per week to maintain skills. Thus, for a single cardiologist, the minimum number of cases is still thought to be 50 per year. Because, as noted, the level of skill and expertise required and the complication rates experienced are related to the type of intervention, credentialing for therapeutic cardiac catheterization should be procedure specific ⁽¹³¹⁾.

A number of considerations must be taken into account when a decision is made regarding the minimum number of cardiac catheterizations that should be performed by a pediatric cardiologist or a PCCL. Importantly, although there are ample data regarding adult interventional procedures, there are no data relating number of pediatric procedures to skill or outcomes. It is important that institutional, local, and personal factors be weighed.

QA plans must be in effect in all PCCLs to monitor outcomes of cardiac catheterization. There are some similarities and differences between the strategy required for QA in the PCCL versus the adult cardiac catheterization laboratory. For example, there is not a prior acceptable rate of normal cardiac catheterizations. In patients undergoing cardiac catheterization for hemodynamic reasons or possible intervention, the rate of normal should be zero. Any number of patients may have electrophysiological abnormalities or acquired disease with structurally normal hearts but abnormal physiology, and these would not be considered to be in the “normal” group. The effort to operate within the published complication rates is the same in all laboratories, although the types and rates of complications in the PCCL are different from those in the adult laboratory. Although intervention procedures are usually planned well in advance, ad hoc procedures might well be required. Such procedures as coil occlusion of a ductus arteriosus or aortopulmonary collateral or balloon dilation with or without stent placement may be needed even when not previously planned. Diagnostic quality and accuracy of catheterizations and procedural outcomes should be examined, with each PCCL responsible for earmarking certain indicators and examining them with plans for improvement if warranted by the data.

F. Procedural Issues

1. Premedication
The choice, dose, timing, route, and overall use of premedication varies widely with age, size, and condition of patient and the experience and training of the operator. There is no “standard” premedication. Chloral hydrate, diphenhydramine (Benadryl®), and diazepam (Valium®) are frequently given orally for sedation. Intravenously, midazolam (Versed®), morphine, fentanyl, hydromorphone (Dilaudid®), and other medicines can be used to good effect. The advantages of midazolam are that it can be given by continuous infusion and it can be reversed if necessary. Reversal of midazolam with flumazenil (Romazicon®) does not usually precipitate the severe discomfort and agitation seen with naloxone (Narcan®) narcotic antagonism. Ketamine may be used in small intramuscular or IV bolus doses for rapid-onset anesthesia. This may help during precise intervention when patient movement might be detrimental to procedure success. Meperidine (Demerol®) alone or in combination with promethazine (Phenergan®) is sometimes used intravenously or by the intramuscular route for analgesia and sedation. Chlorpromazine (Thorazine®) is used less often than previously, because of the availability of and experience with other medicines.

2. Vascular Access Issues
Techniques for venous and arterial access are similar for children and adults. In young children with congenital heart disease, however, much (or all) of the catheterization can often be done from the venous approach. Therefore, there is a greater opportunity for placement of a small cannula in the artery at the beginning of a procedure (rather than the larger sheath). This allows monitoring of blood pressure and sampling of blood gases without the arterial trauma that might be caused by the sheath. If and when the need for retrograde heart catheterization arises, the area around the artery may then be re-anesthetized and the small cannula changed for the appropriate-sized arterial sheath. The transseptal procedure is frequently used for access to the left atrium. Properly performed, this approach does not add significantly to the incidence of complications. It is an important technique for radiofrequency ablation, mitral valve stenosis investigation and valve dilation, prosthetic aortic or mitral valve assessment, and many other catheterization functions. Because of the frequency of venous catheterizations and indwelling femoral venous lines in neonates and infants, limited or absent venous access from the femoral veins is not uncommon. Therefore, venous access from the internal jugular, subclavian, or even basilic approaches is frequent. More recently, the transhepatic approach has been used very successfully for both diagnostic and interventional procedures.

Use of heparin in the flush solutions is routine, but the additional use of bolus-dose heparin depends on the patient’s activated clotting time, procedure type, and vascular approach. It would be usual, for example, not to use bolus heparin for a right-heart catheterization or the prograde right and left-heart catheterization, but heparin would be used in aortic valve dilation. At the end of a procedure an ACT may be checked and if necessary the heparin effect reversed with administration of protamine sulfate in much the same manner as described above for adults. Mechanical plugs or compression devices are rarely used in the PCCL because of the small vessel size. Hemostasis is almost always achievable by direct manual pressure followed by placement of an adhesive or elastic tape over a gauze pad on the access site.

3. Medications Used During the Procedure and Use of Anesthesia
Medications used during the procedures in the PCCL are essentially the same as those noted above for premedication. Repeated bolus doses of sedatives may be used, and/or a continuous infusion of midazolam or other drug may be instituted. It is necessary that a nurse or physician assess and document the patient’s condition after each bolus dose of sedative according to the institution’s conscious-sedation guidelines. It may be useful to consider turning a continuous infusion down or off after the last angiogram or pressure measurement to allow the sedation to begin wearing off as hemostasis is achieved. Systemic arterial oxygen saturation should be continuously monitored by pulse oximetry.

General anesthesia is performed by an anesthesiologist or trained nurse anesthetist under the supervision of the anesthesiologist. Possible indications for anesthesia consultation include patient considerations and procedure characteristics. For example, a developmentally delayed teenager who is fearful may be unable to be sedated without general anesthesia. Patients who are critically ill or in pain will benefit from anesthesia. Prolonged procedures such as radiofrequency ablation or those that require transesophageal echocardiography may be greatly facilitated with general anesthesia. Certain interventional procedures such as aortic or mitral valve dilation, atrial septal defect occlusion, and others may be made significantly easier, safer, and more effective by collaboration with anesthesiologists. Surgical procedures such as pacemaker placement or lead extraction are usually done with the patient under anesthesia. The use of anesthesia is a judgment made by the attending cardiologist in consultation with the anesthesiologist, just as it is in surgery. Wide discretion is allowed and encouraged.

4. Procedural Performance Differences Compared With the Adult Cardiac Catheterization Laboratory

a. Single-Plane Versus Biplane Angiography

The standard equipment in a PCCL includes biplane radiographic equipment. In general, pediatric and congenital cardiac catheterizations are performed using biplane fluoroscopy and angiography. This is important both for localizing the catheter in space within the heart vessels and for reduction in contrast dosage administration. Certain procedures can be routinely performed with single-plane fluoroscopy, including (in many laboratories) electrophysiological study and radiofrequency ablation, some types of atrial septal defect occlusion, and others. Atrial septal defect occlusion is often performed with localization and positioning of the device using transesophageal echocardiography as well as fluoroscopy. Coronary arteriography in children may be performed with single-plane use, especially if it is assisted or performed by an adult cardiologist for whom performance of single-plane floroscopy/angiography might be standard.

b. Hemodynamics

As noted, right- and left-heart catheterization are performed in combination in many pediatric and congenital heart catheterization procedures. In addition to the left ventricular systolic and end-diastolic pressures and aortic or arterial pressures normally obtained in the adult cardiac laboratory, right-heart pressures are standard. Pressure waveforms and determinations of oxygen saturations are generally obtained from each chamber of the heart entered and from the pulmonary arteries or veins, aorta, or systemic veins as indicated during any particular procedure. The routine pressure measurements and recordings necessary are difficult to specify, because they vary widely depending on the anatomy and physiology involved. For example, in a patient with pulmonary valve stenosis, a left ventricular pressure may not be obtained at all, wheres a right ventricular systolic and diastolic pressure recording is mandatory. On the other hand, pulmonary artery pressure, routinely obtained in a right-heart catheterization, may be difficult to obtain or even ill advised in a patient whose pulmonary arteries might have to be entered via a tenuous surgically created shunt. Even an invasive arterial or aortic pressure might not be obtained in the setting of a cardiac transplant repeat biopsy or other limited right-heart procedure. Pressures should be able to be recorded with excellent and reliable fidelity on scales, which range from a full scale of 10 mm Hg to 400 mm Hg. Rapid availability of oxygen saturations and blood gases is essential for interpretation of shunt physiology and patient safety.

c. Angiographic Acquisition Differences

Angiograms are routinely performed with framing rates ranging from 15 to 60 frames per second. The framing rate depends on the patient's heart rate and the types of images to be acquired. For example, during balloon dilation, angiographic images may be acquired at 15 (or even 7.5) frames per second, whereas a ventriculogram in an infant with a high heart rate may require imaging at 30 or 60 frames per second. A wide variety of catheters, appropriate contrast materials, and injection techniques and parameters are available. Contrast is often injected at a faster rate in the PCCL compared with the adult laboratory, because fine details of the anatomy are sought rather than global function or regional wall motion abnormalities. In selected patients, 30 to 40 mL of contrast may be injected over 1 second, for instance. In addition, in most cases, premature ventricular beats or even ventricular tachycardia are better tolerated in younger patients with no ischemic heart disease. Angiograms should be available for immediate review after acquisition on some type of “instant replay” digital playback high-speed disk. Short- and long-term archival of digital data or cineangiograms does not differ from that described in prior sections.

d. Radiation Protection and the Pregnant (or Potentially Pregnant) Patient

The same principles of radiation protection applied in the adult cardiac catheterization laboratory apply in the PCCL. In addition, girls and young women of child-bearing age should undergo testing to ensure that they are not pregnant before having a cardiac catheterization. This might be based on history in some cases (such as if a patient has an implanted chronic chemical contraceptive or if she has had a bilateral tubal ligation or hysterectomy), but it should otherwise include a serum or urine human chorionic gonadotropin level.

If a pregnant patient must be studied, the abdominal and groin areas should be shielded to help reduce any direct x-ray exposure. As noted in the section on radiation exposure, though, scattered x-rays will still occur and could be harmful to a newly developing fetus. Efforts to minimize exposure should include using fluoroscopy or in-laboratory echocardiography rather than cineangiography, limiting total exposure time, using reduced framing rates, using the minimum number of contrast injections, and avoiding angulated views when possible.

e. Shunt Measurements

Important information regarding physiology of congenital heart disease is gathered from measurements of intracardiac shunts. Both right-to-left and left-to-right shunts must be able to be quantitated during the catheterization. Because of the need to determine intracardiac shunting, oxygen saturation samples are drawn from many sites rather than simply from the pulmonary artery for mixed venous oxygen level and from the systemic artery for arterial oxygen level. Therefore, the availability of oxygen saturation measurements and arterial blood gas determinations is essential for the efficient performance of the typical congenital cardiac catheterization. The availability of blood gas measurements also allows for the inclusion of dissolved oxygen in the determination of oxygen content. Measurement of oxygen consumption should also be available.

f. Laboratory Personnel Issues

The laboratory staff in the PCCL should be specifically trained and experienced in the care of infants and children during performance of a cardiac catheterization. The specific responsibilities within the laboratory may necessitate the services of a registered nurse, a licensed practical or vocational nurse, a radiography technician, a certified catheterization technician, or others. It is the responsibility of the director and supervisor of the Pediatric Cardiac Catheterization Laboratory to ensure adequate staffing. On-call cases must be considered, and a complement of personnel adequate for the safe, efficient, and informative conduct of emergent or urgent pediatric catheterizations must be available at all times.