Out-of-Operating Room Procedures—Pediatric
Claudia Mueller MD, PhD1
William E. Berquist MD (Gastroenterology)1
Sarah S. Donaldson MD, FACR, FASTRO (Radiation oncology)1
Anne M. Dubin MD (Pediatric cardiac catheterization)1
Jeffrey A. Feinstein MD, MPH (Pediatric cardiac catheterization)1
Gary E. Hartman MD (ECMO)1
Susan Hiniker MD (Radiation oncology)1
Neyssa Marina MD (Oncology)1
Stanton B. Perry MD (Pediatric cardiac catheterization)1
Kalyani R. Trivedi MD (Pediatric cardiac catheterization)1
Ann Ming Yeh MD (Gastroenterology)1
Komal Kamra MD (Pediatric cardiac catheterization)2
Rebecca E. Claure MD (Radiation therapy, oncology, endoscopy, imaging)2
Brenda Golianu MD (Radiation therapy, oncology, endoscopy, imaging)2
Manchula Navaratnam MD (ECMO)2
Chandra Ramamoorthy MD (Pediatric cardiac catheterization, ECMO)2
Kristin Sun MD (Oncology)2
Claudia Benkwitz MD, PhD (Pediatric cardiac catheterization)2
1PROCEDURAL SPECIALISTS
2ANESTHESIOLOGISTS
PEDIATRIC RADIATION THERAPY
PROCEDURAL CONSIDERATIONSSusan Hiniker
Sarah S. Donaldson
Description: Modern pediatric radiation therapy (XRT) requires that the patient be in a stable and reproducible position for daily treatment. Sharply defined beams with secondary collimation are used to irradiate the tumor volume and to spare normal tissue. Patient movement may undermine techniques for sparing normal tissue, and although movement cannot be completely prevented, it must be minimized. In very young children, it is often impossible to prevent movement and achieve adequate cooperation for radiation treatment. In such cases, daily anesthesia is required. Close cooperation of the radiation oncology and anesthesia teams allows for safe and reproducible daily treatment. In general, children older than 3 or 4 yr can be persuaded to lie still for radiation therapy. Children from 2.5 to 4 yr may cooperate during the treatment (which is usually < 15 min), but not for the treatment planning and simulation, in which an immobilization-stabilization device is made (often requiring 1-1.5 h) (see Fig. 13.2-1). In most infants and young children (< 4 yr), anesthesia is essential.
The optimal position for XRT must also be optimal for the anesthesiologist. Ideally, the area to be treated is determined using 3-dimensional conformal techniques to optimize treatment and to minimize normal tissue exposure. This requires a cross-sectional imaging study (e.g., CT scan), with the patient in the identical position as will be used during the radiation treatment. A series of radiographs are taken at the treatment-planning (simulation) appointment, which typically lasts 1-1.5 h and requires GA. It is essential that there be no patient movement between exposures; if the patient moves, the entire procedure must be repeated. Typically the patient is transported to the CT suite for a 3-dimensional treatment-planning CT scan. Anesthesia preparation may be initiated in the treatment-planning suite, or in a nearby preparation room. After scans are obtained, individual beam-shaping devices are made, and a multistep process of contouring begins for treatment planning.
Seven to 10 days following the initial planning session, the patient often has a verification procedure, which is usually of shorter duration—generally requiring only 30 min of anesthesia time. The verification procedure consists of a series of radiographs using the beam-shaping devices, which simulate the treatment to be given. When this procedure
is successfully completed, the anesthetized patient is moved to the treatment room. The child is put in the identical position achieved during the planning/verification procedures, and treatment is administered.
is successfully completed, the anesthetized patient is moved to the treatment room. The child is put in the identical position achieved during the planning/verification procedures, and treatment is administered.
 Figure 13.2-1. A radiation therapy vault. |
 Figure 13.2-2. A plastic immobilization cast of the head. |
The first day or two, and weekly thereafter, a verification x-ray (called a “port film”) is taken to confirm the accuracy of the treatment field. The treatment itself is only a few minutes in duration for each field; ideally, the entire procedure is completed within 15-30 min. A form of radiotherapy treatment planning and delivery known as intensity-modulated radiotherapy (IMRT) may require slightly longer treatment times due to the larger number and increased complexity of fields treated, while volumetric modulated arc therapy may be of shorter treatment time. A course of treatment may be only a few days or may last for 5-6 wk, generally with treatment given 5 × per week. Occasionally, multiple (2-3) treatments per day are given at 4-8 h (usually 6 h) intervals. At the initial appointment, the patient’s optimal position is determined, an immobilization device is constructed, and measurements are taken. The immobilization device is usually a body cradle or cast, and often a head/face mask is made for head and neck or brain treatment (see Fig. 13.2-2). Initially, temporary marks or Band-Aids® are used; however, when the final positioning has been determined, a more permanent mark, such as a tattoo, may be applied. Often, a head holder with a mask is applied to ensure the position for XRT.
In managing certain brain tumors (e.g., medulloblastoma, high-grade intratentorial ependymoma, germ cell tumors, and CNS leukemia), cranial spinal irradiation (CSI) may be used. Conventionally, this procedure requires that the patient be placed in the prone position with the head flexed as much as possible to minimize a cervical lordosis. This positioning, however, creates special difficulties for the anesthesiologist. If the child is intubated for the setup, the radiation stabilization device must allow space for the ETT. If the child is not intubated, there must be adequate access to the airway. Current techniques allow patients to be treated with CSI in the supine position, facilitating easier airway access for the anesthesiologist, more secure patient immobilization, and faster treatment times.
Fractionation: Pediatric protocols have been testing the efficacy of giving multiple fractions (treatments) of radiation 2-3 × per day, usually at 6-h intervals, to allow higher total radiation doses to be administered with possible less normal tissue morbidity. These schemes have been or are being evaluated for children with central nervous system tumors and total body irradiation (TBI) in preparation for bone marrow transplantation. Until proven to be of increased efficacy, such schemes should remain part of large protocol studies. The timing of radiotherapy may be at 4-, 6-, or 8-h intervals 2-3 × per day, depending on the protocol. These studies provide several challenges for anesthesiologists, radiotherapists, and parents. Radiotherapy under anesthesia, however, has been successfully administered to infants undergoing multiple fractions per day. Attention must be given to potential malnutrition and/or dehydration from prolonged periods of NPO status.
Total-body irradiation (TBI): Although most TBI techniques are administered with the patient standing, infants and small children must lie prone and supine for the treatment. This positioning requires sedation and/or anesthesia. Gastrointestinal upset, sometimes provoked by the radiation, presents an additional challenge for proper radiotherapy technique, as well as for anesthetic management.
Cranial or Body Radiation/Radiosurgery/IGRT: The technique of using precision, stereotactically localized radiation with a highly collimated radiotherapy photon beam, as generated from a linear accelerator, is currently
being employed for select patients with small cranial, base-of-skull, or body tumors. There is increasing enthusiasm for this technique for infants and children with recurrent posterior fossa and cerebral tumors, craniopharyngiomas, optic nerve and chiasmal gliomas, and small AVMs. Radiosurgery has historically required a frame-based technique that requires 6-10 h of continuous anesthesia while a patient undergoes application of a metal frame, CT localization, and multiport radiotherapy treatment. However, newer technology, using image guidance, called image-guided radiation therapy (IGRT) now allows frameless radiation delivery to the cranium or body. This technique requires a 1-1.5 h treatment planning and simulation session followed by a single fraction or limited number of treatment sessions each lasting 1.5-2 h. These approaches require close coordination between the anesthesiologist, neurosurgeon, oncologic surgeon, and radiotherapist.
being employed for select patients with small cranial, base-of-skull, or body tumors. There is increasing enthusiasm for this technique for infants and children with recurrent posterior fossa and cerebral tumors, craniopharyngiomas, optic nerve and chiasmal gliomas, and small AVMs. Radiosurgery has historically required a frame-based technique that requires 6-10 h of continuous anesthesia while a patient undergoes application of a metal frame, CT localization, and multiport radiotherapy treatment. However, newer technology, using image guidance, called image-guided radiation therapy (IGRT) now allows frameless radiation delivery to the cranium or body. This technique requires a 1-1.5 h treatment planning and simulation session followed by a single fraction or limited number of treatment sessions each lasting 1.5-2 h. These approaches require close coordination between the anesthesiologist, neurosurgeon, oncologic surgeon, and radiotherapist.
IMRT/Protons/VMAT: Recent developments in external beam radiotherapy techniques have allowed for increasingly conformal treatment using intensity-modulated radiation therapy (IMRT) or proton therapy. However, these complex techniques generally involve image-guided therapy and a greater number of beam directions, thereby resulting in longer overall treatment times. The development of volumetric modulated arc therapy (VMAT), in which dose is delivered using a single gantry arc rotation, has allowed for treatment of very conformal volumes with increased speed as well as delivery of fewer monitor units. VMAT is increasingly used in the treatment of pediatric patients, particularly in those who require anesthesia during treatment.
Usual preop diagnosis: Leukemia; brain tumors (benign or malignant); retinoblastoma; solid tumors of childhood.
▪ SUMMARY OF PROCEDURES
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▪ PATIENT POPULATION CHARACTERISTICS
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ANESTHETIC CONSIDERATIONSRebecca E. Claure
Brenda Golianu
PREPROCEDUREOrientation to the XRT suite (see Fig. 13.2-1), positive reinforcement, and play therapy can reduce the number of children requiring anesthesia for XRT; however, the majority of children ≤ 4 yr will require anesthesia. A detailed preanesthesia visit is essential and is also an opportunity to gain the confidence of both child and parents. The majority of these patients will have received chemotherapy and should be evaluated for side effects. The importance of NPO status needs to be stressed repeatedly, discussing the potential danger of emesis during treatment. Written instructions regarding preop protocols are extremely helpful in this context. For children with cancer, prolonged preop fasting for XRT once or twice daily could severely compromise an already marginal nutritional intake. Infants, children, and adolescents should be encouraged to drink clear liquids until 2 h before treatment. Milk and solid foods should be held for an appropriate time interval (6-8 h depending on age. See Appendix D). Reassessment before each anesthetic is recommended because the patient’s medical status may change during the course of radiation therapy. Some children will have Sx of ↑ ICP, which must be taken into account when designing an anesthetic plan to avoid ↑ PaCO2 and other factors that may further ↑ ICP.
The most common diagnoses are primary CNS tumor (28-33%), retinoblastoma (9-26%), acute leukemia (9-26%), neuroblastoma (2-18%), lymphoma (8%), rhabdomyosarcoma (5-7%), Wilms’ tumor (5%), and Ewings (5%). The total number of treatments can range from 1 to 65 (median 20-24). Many patients require a mold of the head and neck. Children can range in age from infants to adolescents, with a median age of 2.4-3.8 yr.
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INTRAPROCEDUREAnesthetic technique: Provision of anesthesia to children at sites remote from the OR is challenging. During XRT, patients must remain immobile so that the tumor can be reliably irradiated while minimizing damage to uninvolved tissue. Anesthetic goals should include patient immobility, rapid onset, brief duration of action, and prompt recovery. The anesthetic should allow maintenance of a patent airway and spontaneous ventilation in a variety of body positions. Ketamine is a potent sialogogue and can cause nystagmus, which prevents precision radiation of retinoblastomas. It may cause prolonged or unpleasant emergence and should be avoided in patients with ↑ ICP. Choice of anesthetic technique may be limited by equipment or logistical issues. Anesthesia machines may not be available in all XRT suites.
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POSTPROCEDURE
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Suggested Readings
1. Buehrer S, Immoos S, Frei M, et al: Evaluation of propofol for repeated prolonged deep sedation in children undergoing proton radiation therapy. Br J Anaesth 2007; 99(4):556-60.
2. Keidan I, Perel A, Shabtai E, et al: Children undergoing repeated exposures for radiation therapy do not develop tolerance to propofol. Anesthesiology 2004; 100(2):251-4.
3. McFadyen JG, Pelly N, Orr RJ: Sedation and anesthesia for the pediatric patient undergoing radiation therapy. Curr Opin Anaesthesiol 2011; 24(4):433-8.
4. Parker WA, Freeman CR: A simple technique for craniospinal irradiation in the supine position. Radiother Oncol 2006; 78(2):217-22.
5. Seiler G, De Vol E, Khafaga Y, et al: Evaluation of the safety and efficacy of repeated sedations for the radiotherapy of young children with cancer: a prospective study of 1033 consecutive sedations. Int J Radiat Oncol Biol Phys 2001; 49(3):771-83.
6. Tsai YL, Tsai SC, Yen SH, et al: Efficacy of therapeutic play for pediatric brain tumor patients during external beam radiotherapy. Childs Nerv Syst 2013; 29(7):1123-9.
PEDIATRIC CARDIAC CATHETERIZATION AND ELECTROPHYSIOLOGY
PROCEDURAL CONSIDERATIONSKalyani R. Trivedi
Anne M. Dubin
Stanton B. Perry
Jeffrey A. Feinstein
Cardiac catheterization and electrophysiology testing have evolved over the recent decades from purely diagnostic tools to combined diagnostic and therapeutic procedures. Although the use of GA varies from institution to institution, higher levels of sedation are required at a minimum for critically ill patients, those requiring complex interventional strategies, small children who must remain totally still, and when TEE is used for image-guided therapy. A thorough review of diagnostic and interventional cardiac catheterization and electrophysiology is not possible in this chapter, and the interested reader is referred to the multiple textbooks available on the subject.
The placement of anesthesia equipment for these procedures must allow for (a) proper positioning of the patient, (b) easy access to the head and neck and/or groin for the physician performing the procedure, and (c) rotation and angulation of the imaging equipment. The goal of sedation in all of these procedures is to provide a nontraumatic, safe environment for the patient. Many patients can be cared for adequately and safely using conscious sedation; however, there is a subset of pediatric patients who may require GA. This group may include patients with complex congenital heart disease, ventricular dysfunction, or airway abnormalities. It is important to understand that certain anesthetic agents may alter cardiac conduction, making arrhythmia inducibility more difficult. Catecholamine-dependent arrhythmias, such as an automatic atrial tachycardia, may be impossible to induce with the patient under GA. Furthermore, the arrhythmia itself may complicate anesthetic care, by causing sudden decreases in BP due to excessively rapid rates. In patients undergoing radiofrequency ablation (RFA) in areas close to other critical structures of the heart, GA may be necessary to keep the patient motionless during application of energy.
VASCULAR ACCESS
The modified Seldinger technique of cannulating blood vessels percutaneously is used to establish vascular access for cardiac catheterization. (The femoral, IJ, and subclavian veins are most commonly used for venous access.) Transhepatic access to the IVC has been used safely and successfully in patients without femoral venous access. The femoral artery is most commonly used, although the carotid and axillary arteries may be used for specific procedures or when there is bilateral femoral artery occlusion. In newborns, the umbilical artery and vein may be used. Access may be especially difficult in patients who have undergone multiple previous procedures. In the most severe cases, reconstructive transcatheter techniques, including balloon angioplasty and stent implantation to rehabilitate the vessels, have been used to allow future catheter-based diagnostic and therapeutic interventions.
Infiltration of the skin and the subcutaneous tissues with a local anesthetic agent to reduce pain is used when the procedure is being performed under conscious sedation. With GA, infiltration of a local anesthetic agent may be deferred to the end of the procedure to alleviate pain and discomfort at vascular access sites during recovery.
HEMODYNAMIC DATA
O2 sat measurements are made routinely in the various cardiac chambers, vena cavae, and great vessels. These measurements are used to calculate the systemic flow (CO, Qs), pulmonary flow (Qp), the ratio of the pulmonary to systemic flow (Qp:Qs), and PVR and SVR.
It is ideal to obtain the data with the patient awake and breathing spontaneously in room air. This is rarely possible in pediatric patients. The use of light anesthesia and sedation during the diagnostic part of the study facilitates acquisition of data in as near-normal state as possible. It is important to recognize and limit effects on intracardiac and intrapulmonary pressures and systemic and pulmonary resistances when the procedure is done under GA with IPPV. At a minimum, and when tolerated, baseline hemodynamic measurements should be performed with an FiO2 as close to 0.21 as possible. In some cases, additional diagnostic information may be collected to study the effects of O2, NO, vasodilators or inotropes, exercise and balloon occlusion of intracardiac or extracardiac shunts on the CO, pulmonary flow, and PVR and SVR.
From O2 sat, dissolved O2 (PO2), and Hb measurements, the O2 content (mL/dL) of the mixed venous blood and systemic arterial blood is used to calculate systemic AV O2 content difference. Pulmonary AV O2 content difference is similarly estimated by calculating the O2 content of pulmonary venous and arterial blood. Systemic (Qs) and pulmonary flow (Qp) can then be derived using the Fick principle:
When the partial pressure of dissolved O2 is < 100, the PO2 portion of the equation can be negated, and the flow can be calculated using the O2 consumption and O2 sat measurements alone.
Based on Ohms law, which states V = IR, where V = voltage (or pressure drop) across a circuit, I = the current (or flow) through the circuit, and R = the resistance in the circuit. SVR and PVR can be calculated as follows:
PVR = (PAp – LAp)/Qp
SVR = (Aop – RAp)/Qs
Where PAp = pulmonary artery pressure; LAp = left atrial pressure; Aop = aortic pressure; and RAp = right atrial pressure; pulmonary vascular resistance = PVR; systemic vascular resistance = SVR.
ANGIOGRAPHY
Biplane cineangiography is performed to delineate intracardiac or vascular anatomy and to evaluate ventricular function. Images are obtained by injection of radiographic contrast agents through angiographic catheters positioned in appropriate locations. The angiograms may be performed in posteroanterior and lateral projections or by angling the cameras to obtain cranial, caudal, left anterior, or right anterior oblique projections. Based on the site of injection and the information required, the injection may be performed with a power injector, delivering large amounts of contrast quickly, or by hand.
INTERVENTIONAL PROCEDURES
Valvuloplasty
Aortic valvuloplasty: A retrograde approach from the femoral artery generally is used, although an antegrade and transseptal approach from the femoral vein is preferred by some. In either approach, following hemodynamic evaluation and angiographic estimate of the aortic valve annulus, a wire is positioned across the valve, and a balloon catheter is advanced over the wire and positioned across the aortic valve. The balloon is then inflated and deflated quickly. The inflation of the balloon leads to a transient loss of CO, ↓ SBP, and occasionally may be accompanied by ↓ HR. These hemodynamic changes recover quickly on balloon deflation. Although complications of aortic valvuloplasty are rare, the anesthesiologist must be “prepared for the worst,” which includes annular rupture and the creation of significant aortic regurgitation.
Pulmonic valvuloplasty: After femoral venous or IJ access is obtained, the technique for balloon dilation of the pulmonary valve is nearly identical to that outlined above for the aortic valve. Loss of CO and ↓ HR are seen during the time of balloon inflation with this intervention as well. Although annular rupture also is a potential complication of this procedure, the creation of pulmonary insufficiency is of less concern and better tolerated than aortic insufficiency.
Angioplasty
A number of transcatheter treatment options are available for management of pulmonary artery stenoses, including balloon angioplasty and endovascular stent implantation. Angioplasty has been shown to be highly effective in anatomically appropriate cases with a low complication rate. Hemodynamic and angiographic assessment of the lesion is obtained, followed by selection of an optimal balloon catheter, based on both the size of the stenosis and surrounding “normal” tissue. Using the same “over-the-wire technique,” a balloon is advanced and centered over the stenosis. Hemodynamic and angiographic data are assessed following each intervention. A high index of suspicion for complications— including dissection or pulmonary artery tear, obstructive intimal flaps, thrombi, and reperfusion pulmonary edema— is justified, as management may require ventilatory manipulations and/or emergent cardiovascular resuscitation.
Balloon angioplasty of coarctation of the aorta may be performed for treatment of native or recurrent coarctation. Angiography of the aorta is performed to delineate the coarctation and estimate the dimension of the coarctated segment and the adjacent aorta. As with other angioplasty techniques, the balloon size is based on the dimensions of the stenotic area and surrounding vessel. Transient loss of lower body perfusion and ↓ HR are to be expected, as with balloon valvuloplasty, on inflation of the balloon. Pressure and angiographic data are obtained to determine adequacy of results and absence of complications. There is a 4-5% incidence of intimal tear and dissection that, in most cases, are nonprogressive. Rarely, aortic disruption may require emergent surgical repair.
Endovascular Stent Placement
Stent implantation in the pulmonary arteries or for aortic coarctation is used to maintain vessel diameter and decreased gradients in patients unresponsive to balloon dilation. Stents are mounted on balloon catheters, and the balloon/stent combination is advanced over a previously placed wire. A long sheath (originating in the groin or neck) is placed across the area of narrowing to prevent the stent from slipping off the balloon catheter as it makes its way through the heart or vessels. After the stent has been properly positioned, the long sheath is withdrawn to expose the balloon/stent combination. The balloon is inflated to expand the stent and appose it to the vessel wall. Placement of long sheaths, particularly through the right ventricular outflow tract (RVOT), can be difficult and may result in transient bradyarrhythmias and loss of CO.
Closure of Congenital Defects
Atrial septal defects (ASDs): As many as 80-85% of secundum ASDs may be amenable to device closure in the cath lab. Most devices currently used include a left atrial disc with an occlusive membrane, a central spool or connecting pin, and a right atrial disc with an occlusive membrane. The membrane occludes flow through the defect, and within months, the device becomes incorporated into the septum due to endothelialization. A sizing balloon inflated across the defect permits estimation of the stretched diameter. A long sheath is then placed across the defect over a wire. The device attached to the delivery cable is loaded in the long sheath and advanced to the left atrium. The left atrial disc is opened, the device is withdrawn until the left atrial disc is in contact with the atrial septum; then the right atrial disc is opened, effectively “sandwiching” the atrial septum between the two discs. TEE is used to guide placement of the device. Intracardiac ECHO offers ECHO guidance without the requirement of GA.
Ventricular septal defect (VSD): Closure with a device can be performed in the cath lab for isolated or multiple muscular VSDs, as well as perimembranous defects. The technique requires establishment of a continuous AV guide wire loop across the defect. Most often, the wire course is from the femoral vein, through the right atrium, into the RV, across the VSD, out the aortic valve, around the aorta, and out the femoral artery. The device is then deployed via a long sheath placed across the VSD through the RV aspect. Hemodynamic compromise may be seen with tension on the wire if aortic or tricuspid insufficiency is induced. Transient arrhythmias are routine while crossing the VSD and deploying the device. Great care must be taken to avoid entrapment in the mitral, aortic, and tricuspid valves during device deployment. In addition to fluoroscopy, TEE is used to guide placement of the device. Improvements in the devices developed more recently have significantly reduced the cath lab morbidity of this procedure.
Coil occlusion: Aortopulmonary collaterals, AVMs, Blalock-Taussig (B-T) shunts, venous collaterals, coronary artery fistulae, and patent ductus arteriosi (PDA) have all been successfully occluded using the technique of coil
embolization. The embolization coils consist of a metal wire, either stainless steel or platinum, ± Dacron strands, and are available in multiple sizes, lengths, and shapes. Although PDA or coronary artery fistula embolization may obviate the need for surgery, most embolizations serve to either reduce the cardiac workload by decreasing the amount of shunting or simplify a planned surgical procedure.
embolization. The embolization coils consist of a metal wire, either stainless steel or platinum, ± Dacron strands, and are available in multiple sizes, lengths, and shapes. Although PDA or coronary artery fistula embolization may obviate the need for surgery, most embolizations serve to either reduce the cardiac workload by decreasing the amount of shunting or simplify a planned surgical procedure.
The technique for coil closure of collaterals or other communications is straightforward. A catheter is placed in the vessel to be occluded, and a selective angiogram is done to delineate the anatomy and diameter of the vessel to be closed. Coils that are slightly larger than the diameter of the vessel are used because the vessel will distend when the coil is deployed. Using a long “pusher” wire, the coil is advanced through the catheter and deployed in the vessel. Repeat angiography is performed to confirm complete closure. If residual flow remains, additional coils are placed. Coil dislodgement and embolization to a distal blood vessel are the most common complications. In general, the errant coil can be retrieved in the cath lab without much difficulty and a new coil of a larger size placed to occlude the vessel.
OTHER PROCEDURES
Endomyocardial biopsy is commonly performed for rejection surveillance in patients following cardiac transplantation. It also may be performed in patients presenting with acute onset of cardiomyopathy for histopathological Dx of myocarditis. The preferred site for obtaining cardiac biopsy is the RV aspect of the intraventricular septum. The specimen is obtained with a biopsy forceps advanced to the RV through a long sheath. It is usual to obtain four to five specimens to improve the diagnostic gain, as the histopathological changes can be patchy. Complications of endomyocardial biopsy include cardiac perforation and tricuspid valve damage. GA is required in patients with compromised airway and/or cardiopulmonary status from lymphoproliferative disease or obesity 2° to steroid therapy.
A variety of other transcatheter therapeutic procedures may be performed in the cardiac cath suite. Rashkind balloon atrial septostomy, static balloon septoplasty, Brockenbrough transseptal needle puncture, and radiofrequency-assisted perforation of the pulmonary valve or the atrial septum are all less commonly used than the procedures described above, but routinely are undertaken in high-volume cath labs.
ELECTROPHYSIOLOGY STUDY (EPS)
Patients with atrial or ventricular arrhythmias may require either diagnostic or therapeutic interventions in the cath lab. EP studies are catheterization procedures in which intracardiac electrical signals are recorded via specialized catheters that can both record electrical activity and stimulate the heart. These studies often are used to make a Dx of the mechanism of arrhythmia, assess the hemodynamic impact of the arrhythmia, assess efficacy of pharmacologic therapy, and map the location of abnormal conduction pathways or automatic foci. Although routine studies usually take 2-3 h, some may be quite lengthy.
