Cardiac Catheterization in Adult Congenital Heart Disease

History and Imaging

A review of the patient’s clinic chart with specific attention not only to the native anatomy but also to the details of previous surgical and interventional repairs is paramount. A tattered 25-year-old surgical report may be a holy grail of information. A seasoned surgeon’s operative report may describe the native and surgical anatomy in great detail and provide insight into what was repaired, how, and why. The surgical report may be the only reliable source as to the size and type of implanted surgical valve or conduit. As any experienced ACHD physician will note, we play broken telephone too often when following patients over decades; all it takes is an errant word or typographic error to alter the substance of the anatomic problem. A close second in the hierarchy is a good-quality computed tomography (CT) scan or MRI by an experienced imager. Finally, review of previous hemodynamic and angiocardiographic evaluations helps to consolidate an understanding of potential procedural issues that may not otherwise be apparent. As an example, knowledge that an unusual catheter shape or technique was helpful in entering an anomalous vessel or chamber at a previous catheterization may facilitate the subsequent procedure significantly, limiting contrast and fluoroscopy. Vascular access is another example: If a patient is known to have had an occluded right iliac venous system as a child, there is not much hope that it has spontaneously recanalized as an adult, and thus alternative plans should be made.

More crucial than the newest technology and expensive equipment is the availability of imaging experts to conduct the study, interpret it, and caution us of any limitations. Collaboration among the imager and clinical, surgical, and interventional physicians allows the integration of knowledge and facilitates the delivery of excellent patient care. Little is gained from the ability to produce beautiful images that are interpreted in a way that is not meaningful to the clinician. It is as important for the radiologist to know the concerns of the surgeon and interventionalist, as is the reverse. Choosing the right modality to answer a particular set of questions is key, as is providing the imager with a clear articulation of the diagnostic question so that correct protocols are used to obtain the information required.

What Information is Essential?

The operator must have a thorough understanding of the anatomy and physiology of all congenital cardiac defects, associated abnormalities, therapeutic options for the defect under investigation, and information the surgeon/interventionalist will require if the patient is referred for treatment. Before starting it is critical for the ACHD interventionalist to know the following:

• What information is essential to establish the diagnosis or plan the treatment

• What information would be useful to obtain but is not critical

• What information is redundant and already available from other imaging studies

When thought and preparation have been given priority before the procedure, the catheterization can be more efficient in achieving the stated goals while minimizing radiation exposure, volume of contrast media, and procedural risk. The following are specific questions in procedural planning:

• 1.

  Am I aware of the information that is crucial to complete the procedure? Example: Is a descending aortogram required to map an anomalous vessel?

• 2.

  How will I gather the information required to establish the diagnosis; to define the anatomy, physiology, and presence of associated anomalies; and provide the surgeon and ACHD clinician with the information necessary?

• 3.

  Will I need additional noninvasive testing either before or after the catheterization to better answer the diagnostic question?

• 4.

  Is moderate sedation administered by the interventional cardiologist adequate or will deep sedation or general anesthesia be required, such as in adult patients with developmental delay?

• 5.

  Are there comorbidities that might add to the risk of a complication, and, if so, what are the potential preventive measures? Examples: Contrast-induced nephropathy (CIN) risk from baseline renal dysfunction, latex allergy, or history of heparin-induced thrombocytopenia that will require removing heparin from flush solutions.

Not uncommonly, complex cases can become unintentionally long or, worse, be completed without obtaining a key piece of information. The most common essential information required for management decisions concerns the pulmonary vasculature: the PA pressure and resistance, the reactivity of the pulmonary vasculature, and shunt calculations. If access to the PA is difficult, this may prolong the procedure, but time invested here may be far more valuable than recapturing other data already clear from other diagnostic testing. This is never more relevant than when surgical shunts or aortopulmonary collaterals contribute flow to the pulmonary circulation. Similarly the temptation may occur to defer coronary angiography after a difficult procedure in a young adult at low risk for atherosclerosis, thus missing the opportunity to detect a relevant congenital anomaly of the coronary circulation that may directly impact future decisions. As our adult patients age, they may also develop acquired circulatory conditions (eg, coronary artery disease) that may complicate their course. Detection of atherosclerotic coronary disease, coronary compression, elongation, or torsion in patients with symptoms that may be multifactorial is always of importance.

In cases in which a therapeutic intervention is preplanned and focused, such as a coarctation stent, the diagnostic component and intervention may be performed in the same setting. In complex ACHD patients, one must weigh the risks and benefits of ad hoc interventions. Immediate interventions after diagnostic catheterization improve efficiency, minimize the risk of repeat access, and reduce the number of total procedures; however, they are at the cost of increased contrast, fluoroscopy exposure, and on occasion inadequate discourse with the patient. In ACHD patients, optimal treatment decisions should involve multidisciplinary discussions to help to dictate care.

Which Catheters to Use and The Sequence of Events?

The prepared operator will go into the cardiac catheterization laboratory with a clear idea of which catheters are likely to be most helpful and the sequence to obtain the required information. For example, it may be useful to begin the right-sided heart catheterization with a steerable catheter, such as a Goodale-Lubin catheter (Medtronic, Minneapolis, Minnesota), to sample oxygen saturation, probe for atrial septal defects (ASDs) and anomalous venous drainage, and then change to a balloon-tipped catheter to cannulate the PA through a difficult right ventricular outflow tract (RVOT). A modified Judkins right coronary artery catheter with side holes near the tip is also of great value, easing pressure measurements and oximetric sampling in tight spaces. Preplanning of when a catheter with radiopaque markers is needed for measurements or when a multitrack catheter will allow for hemodynamics and high-pressure injections without losing wire access can save considerable time.

When possible, all hemodynamic measurements and oximetry samples should be performed close together in a steady state and on room air. Venous pressures and saturations should be obtained in a structured predictable order so that all the right- and left-sided hemodynamic information is obtained before administering contrast. Having a routine approach allows the nursing staff to anticipate, prepare, record, and chart the procedure accurately.

One should make a checklist at the beginning of the procedure, outlining the hemodynamic information to be obtained, expected chamber/vascular angiography, catheters that will be necessary, and the procedural sequence to be followed. A team huddle prior to the procedure is invaluable to explain the patient’s reason for catheterization, clinical concerns, and going through the expected sequence of events. “Time outs” and checklists, shown by the World Health Organization to reduce operative error, and adapted from the operating room, are now a standard part of the catheterization laboratory ( Fig. 10.2 ). These important protocols have been shown to improve safety and efficiency and must be adhered to.

What Can Go Wrong?

Common problems with cardiac catheterization studies in adult patients with congenital cardiac disease relate to the following:

• Patient pain and anxiety and, as a result, oversedation

• Prolonged catheterization time and contrast administration

• Inadequate, missing, or nondiagnostic information

• Catheter complications

Every case starts with the patient’s comfort and best interest as paramount. ACHD patients cover the age spectrum, and, although they may be well versed with medical procedures, procedural anxiety and pain from access must always be adequately addressed. Caring for a patient who has had multiple procedures requires not only the management of the present procedure but also the sequelae and inadequacies of prior procedures. As per the standard of care in children, their prior catheterization laboratory experience may have included general anesthesia as opposed to conscious sedation used in most adult cases. Considerations for adequate sedation, intravenous anesthesia, and local anesthesia are important. In addition, a kind and calming distraction in the form of reassurance, and the caring touch or handholding of an unscrubbed team member often provides comfort and assists the process. The physiologic response to pain can alter steady state and dramatically affect the hemodynamic conclusions. A vagal reaction from access or pain from catheter manipulation at the access site can alter the steady state and jeopardize the integrity of the information obtained. This is usually amplified in ACHD patients who have had many procedures with dense scar tissue at the site of the puncture. An appropriate amount of sedation for most adults is mandatory. Caution should be exercised to “start low and go slow.” The oversedated patient may develop airway obstruction, hypercarbia, systemic hypoxemia, and elevated pulmonary pressures.

Most ACHD procedures can be expected to take substantially more time to complete than the usual right-sided and left-sided heart procedures in patients with coronary or valvular heart disease, particularly if an unexpected finding arises during the procedure. One way to ascertain that the procedures are kept short is to ensure that the invasive test is performed after all relevant noninvasive tests to avoid repeated documentation of known facts. In general, longer procedural times are associated with increased contrast and fluoroscopy. With the aging of the ACHD population and the accumulation of comorbidities, it is of utmost importance to minimize the risk of CIN from the administration of large volumes of contrast agent to document anatomy that is already well appreciated through other cross-sectional imaging modalities ( Table 10.1 ). CIN risk is especially poignant in patients with bidirectional cavopulmonary anastomosis or Fontan surgery. Prehydration, use of low osmolar contrast agents, and cessation of nephrotoxic medications are all strategies that can help prevent CIN development. There is also a growing recognition to the lifetime stochastic risks of radiation exposure, especially to an ACHD population that may require multiple radiologic tests throughout their lifespan. Decreasing fluoroscopic exposure during the case using best practice radiographic techniques is important; the radiation dose should be as low as reasonably achievable to achieve diagnostic images.

Catheterization Laboratory Infrastructure

ACHD and structural procedures have different requirements than adult coronary or peripheral vascular interventions. Modern designs of congenital and structural catheterization laboratories are larger in size to accommodate additional personnel and imaging modalities. Anesthesiologists and echocardiographers are frequently present in complex interventions, especially for intraprocedural transesophageal echocardiography (TEE) guidance. The structural catheterization laboratory must include (1) fluoroscopic digital flat panel monitors to allow for x-ray visualization and hemodynamics from both sides of the table, (2) adequate radiation protection for staff, (3) monitor integration for real-time echocardiography during the case, and (4) biplane fluoroscopic heads with larger size than coronary imaging to allow for adequate coverage for systemic angiography (eg, pulmonary angiography). (5) The ideal ACHD catheterization laboratory should also be a hybrid suite with operating room–style ventilation and technical standards suitable for cardiopulmonary bypass, mechanical ventilation, and cardiovascular surgery.

ACHD interventions often rely on real-time TEE or ICE and the interpretation of CT/MRI cardiovascular imaging to guide treatment strategy. Catheterization laboratory systems should be able to display prior imaging studies tableside simultaneously with live fluoroscopy and ultrasound imaging. Technology harmonizing TEE ultrasound with fluoroscopy allows localization of precise structures in real time on fluoroscopy. Modern catheterization laboratory systems can also use superimposed 3D CT- or MRI-guided roadmaps to direct complex interventions. The ability to perform real-time 3D rotational angiography is also of increasing importance.

Basic catheterization laboratory Equipment

A vast array of wires, catheters, stents, embolization devices, stents, valves, and retrieval devices are needed to address congenital heart lesions in a variety of sizes and configurations. There are few things as disappointing to the operator or patient as arriving at a particular point during a procedure and a particular piece of equipment required to complete the procedure is unavailable. A well-planned procedure will include consideration of the inventory required. However, an abundance of equipment will necessitate that some equipment that will need to be discarded because of date of expiration; this should be looked on as a necessary evil. Careful inventory planning and management is absolutely essential to reduce waste.

Sheaths

A selection of short and long sheaths from 4 to 25 French (Fr) is required. Large-caliber stents needed for coarctation or pulmonary outflow tract treatment can necessitate sheath size up to 16 Fr (eg, for covered stent implantation using a balloon delivery system). Most available transcatheter valves come with their own proprietary sheaths ranging between 14 and 24 Fr. Similarly, companies selling occlusion devices or plugs often sell corresponding delivery sheaths (eg, TorqVue delivery systems for Amplatzer devices [St. Jude Medical, Saint Paul, Minnesota]). Although the size match with these proprietary sheaths is guaranteed, alternate sheaths with adequate inner lumen accommodation can also be used.

There are various Mullins-type sheaths that should be purchased with radiopaque tip markers ( Fig. 10.3 ). In addition, some operators use kink-resistant long sheaths. Such sheaths are advantageous when there is peripheral tortuosity, when large loops in the right atrium are required or the RVOT has an acute angulation, or when delivering devices to the pulmonary arteries. Finally, there is a utility for steerable sheaths, such as Agilis NxT Steerable Introducer (St. Jude Medical), for improved stability and better catheter access and support, such as in interventions involving the pulmonary veins or mitral valve ( Fig. 10.4 ).

Guide Wires

Guide wire sizes range from 0.014 to 0.038 inches in diameter and from 50 to 260 cm in length. Their design includes wire cores with varying degrees of tensile strength and outer coatings that can differ in hydrophilic and lubricious characteristics. The distal 1 to 5 cm end of the wire is often distinct in design and maneuverability from its remaining length; this end often determines a wire’s utility ( Fig. 10.5 ). For example, wires can be labeled as super floppy, ordinary, super stiff, hydrophilic, and glide (eg, Terumo, Sommerset, New Jersey). Spring coil design wires with hydrophilic coating on the distal end are invaluable to engage tortuous vessels while allowing adequate support for catheter exchange (eg, Wholey, Coviden, Plymouth, Minnesota, and Magic Torque, Boston Scientific, Natick, Massachusetts).

The Amplatz super-stiff and ultra-stiff guide wires (Cook Medical, Bloomington, Indiana) (0.025 to 0.038 inch) are the mainstay for almost every case in stabilizing balloons across high-flow lesions and during stent implantation or valvuloplasty. The Meier Backup wire (Boston Scientific) and Lunderquist extra stiff wire (Cook Medical) have been invaluable for transcatheter pulmonary and aortic valve implantation when tortuosity and calcification is a problem. In addition, different 0.014 coronary wires are important to have on hand to engage coronary fistulas and small tortuous arterovenous malformations.

Catheters

A variety of catheters are required; basic configurations such as Amplatz, multipurpose, Goodale-Lubin, Gensini, pigtail, Cobra, Vertebral, and Judkins coronary catheters are essential ( Fig. 10.6 ). These catheters will need to be stocked in a variety of sizes and configurations. The presence of radio-opaque markers on available catheters can be important for calibration and confirmation of any angiographic measurements. It is helpful to stock a series of 4- to 5-Fr hydrophilic catheters in lengths of 100 and 120 cm. These catheters will track through almost any tortuous bend to a destination often unreachable by standard catheters. They permit pressure monitoring from these locations, as well as exchange for stiffer wires to deliver sheaths required for therapy. The Multi-Track angiographic catheter (Braun, Bethlehem, Pennsylvania) allows pressure measurements and high-pressure injections while still maintaining distal wire access ( Fig. 10.7 ). These catheters are invaluable, particularly for RVOT/main PA injections in the setting of pulmonary insufficiency. Use of a pigtail or other side-hole catheter in this location often results in recoil and loss of position with high-pressure injections. They are available with a set of distal marker bands for size calibration.

Swan Ganz and PA catheters are a mainstay of all right heart catheterization—but especially important to use when performing interventions in the RVOT or PAs to avoid damaging the tricuspid valve chordae when later exchanging to large-bore sheaths. Wedge catheters can allow for selective PA/wedge angiography to visualize levophase pulmonary venous return and to confirm the wedge position for pressure measurement. Long microcatheters with lumens that accept 0.018-inch wires should be available for coil delivery. Tapered and nontapered catheters, guiding catheters, and balloon wedge (end-hole) and angiographic (side-hole) catheters, such as the Berman catheters (Arrow Inc, Reading, Pennsylvnia), are the foundation of any interventional laboratory (see Fig. 10.7 ). A balloon-tipped Berman catheter can be useful to float into distal PAs while its side holes allow for high-pressure angiography without exchange; the limitation of these catheters is the inability to measure the pulmonary capillary wedge pressure.

A comprehensive stock of catheters is an asset. Each operator will choose an appropriate selection and become familiar with their use. The more complex the case mix, the greater the variety of catheters that will be needed in the inventory.

Balloons

ACHD interventions require a large variety of balloon sizes and types that run the gamut from designs for coronary interventions, peripheral arterial procedures, and valvuloplasty. Given the variability of procedures and patient population, equipment will range in size, length, design, material, and limitations. Many balloons adapted for ACHD interventions may not have been initially produced for intracardiac or pulmonary applications but rather for peripheral angioplasty ( Fig. 10.8 ). Low-pressure balloons (eg, Tyshak I & II and Z-Med I & II from NuMed Inc, Cornwall, Ontario, Canada) are available in a range of sizes (4 to 30 mm in diameter with 4- to 13-Fr shafts). They are especially advantageous because of their rapid deflation rates, which limit the time an outflow tract is occluded during an inflation cycle. High-pressure balloons also come in a range of sizes and lengths from a number of manufacturers (eg, Mullins-X from NuMed or Atlas from Bard, Murray Hill, New Jersey). Other noncompliant balloons (Atlas Gold and Vida balloons from Bard) have advantages of shorter shoulders on inflation and minimize vessel straightening. The Conquest balloon by Bard is an ultra-noncompliant balloon that prevents any balloon overexpansion from predicted diameters even at very high pressures.

Most balloons can be used as platforms for stent delivery. The BIB (balloon in balloon) from NuMed is very popular for controlled expansion and is especially useful for stent delivery (sizes 8 to 24 mm in diameter). A large range of balloon sizes, as well as an adequate selection of high-pressure balloons, is essential ( Fig. 10.9 ).

Transseptal Equipment

Transseptal needles, using the Mullins transseptal technique, will occasionally be required to enter the left side of the heart, cross through a lateral tunnel Fontan, enter the pulmonary venous baffle in a Mustard/Senning patient, or perforate an atretic vascular structure. For the adult, generally two lengths of transseptal needle can be stocked ( Fig. 10.10 ), a standard (71 cm) and a long (89 cm) length needle if an Agilis sheath is required to reach the septum in massive right atrial dilation. It is usually wise to begin with the standard small transseptal curve and trade upward in case of failure. In addition, the hub of the dilator should be such that when the needle and hub are engaged, only 2 or 3 mm of the needle is exposed from the tip. A useful trick for difficult transseptal punctures is to reintroduce the obturator shipped with these devices (usually removed and discarded when the needle is flushed prior to introduction). There are different curves to modern day transseptal sheaths, accounting for where on atrial septum it would be most advantageous to cross (eg, more inferior for mitral balloon valvuloplasty and more superior for MitraClip interventions). Swartz SL Series of 8- and 8.5-Fr sheaths (St. Jude Medical) come in a 63- or 81-cm length with a primary curve of 50 degrees and variable secondary curves (SL0: 0 degrees; SL1: 45 degrees; SL2: 90 degrees; SL3: 135 degrees; SL4 180 degrees). When engaging the pulmonary veins, SL0 or SL1 may be adequate, whereas for mitral valve interventions, SL2 or SL3 may provide a more posterior orientation. For medial-oriented mitral perivalvular leaks, SL4 curve may be optimal.

Surgical material, such as that of extracardiac Fontan tunnels, can occasionally be challenging to cross with transseptal needles; in these cases, radiofrequency ablation (RFA) needles have proven useful (see Fig. 10.10 ). As long as the anatomy is well understood and there is minimal calcification, RFA can offer variable penetration across most fabrics (eg, Dacron, polytetrafluoroethylene [PTFE], or Gore-Tex), although there are limitations to this technique.

Embolization Equipment

In patients with congenital heart disorders, vascular embolization is achieved by either coils or adaptation of septal and vascular occluder devices, such as ductal, atrial, and patent foramen ovale (PFO) defect occluders.

Coils

Historically, the Gianturco free release coil (Cook Medical) has been the primary device for peripheral embolization; however, controlled release coils (in which coil release is dependent on an active maneuver from the operator) offer a safer implant, especially in higher-flow lesions or areas where precise coil implantation is critical. A large variety of coil sizes, lengths, and shapes are available from various suppliers. A selection of guide catheters and microcatheters should be available for coil delivery ( Fig. 10.11 ). Controlled release coils can be retrieved and repositioned before release. Of note, controlled release coils that use electrolytic detachment should be avoided in the coronary arteries because they can result in chest pain with ECG changes. Coils that use a mechanical release mechanism are generally safe in all situations. Such coils are atraumatic to the vasculature, with low radial friction in the delivery catheter lumen allowing for ease in delivery even in tortuous segments. For an effective occlusion, a dense mass of thick, long coils is optimal. Modern-day coils, such as MReye Embolization Coil (Cook Medical), are safe for future MRI scanning, which is important in our ACHD population.

We prefer platinum coils that allow for future MRIs without the artifact of stainless steel, which is especially important in young patients. We primarily use controlled release coils, given their advantages of repositioning. In situations of high flow in which a large number of coils would be required to achieve embolization, a plug may be the preferred strategy.

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here