Echocardiographically Guided Electrophysiologic Testing in Pregnancy

MichaelS. Lee, MD, Steven J. L. Evans, MD, Steven Blumberg, MD, Monty M. Bodenheimer, MD, and Scott L. Roth, MD, New Hyde Park, New York

Electrophysiologic testing is usually performed with fluoroscopy to guide catheter positioning. This method of visualizing catheter placement may not be ideal for patients who are pregnant. We report four cases of echocardiographically guided placement of catheters for electrophysiologic testing because of the consideration of pregnancy. Adequate visualization of catheters was possible, allowing for proper catheter positioning and complete electrophysiologic testing, including the recording of atrial, His-bundle, and ventricular potentials, as well as cardiac stimulation and induction of tachycardia. This method holds promise for patients in whom fluoroscopy may be relatively contraindicated, such as pregnant patients, as well as patients in whom it is desirable to avoid x-ray exposure such as women of childbearing age and young children. (JAM Soc EcHOCARDIOGR 1994;7:182-6.)

Although catheter positioning during electrophys­iologic testing is generally performed with x-ray fluo­roscopy to guide catheter position, two-dimensional echocardiography is an alternative method of guiding catheter placement. Echocardiographically guided catheter placement obviates the need for irradiation and may be of utility for patients in whom radiation exposure is undesirable, such as women of child­bearing age and especially women who are pregnant.

METHODS

A standard two-dimensional echocardiogram was obtained before electrophysiologic testing and eval­uated for adequacy of visualization of the heart cham­bers on the right side. The inferior vena cava, right atrium, high right atrium, tricuspid valve, tricuspid annulus, and right ventricle (RV) (including apex) were well visualized in all patients. After informed consent was obtained, the patients were brought to the electrophysiology laboratory in the fasting state. In the first patient a right antecubital cutdown was

From the Division· of Adult Cardiology, the Harris Chasanoff Heart Institute, Long Island Jewish Medical Center.

Reprint requests: Steven J. Evans, MD, Division of Adult Car­diology, the Harris ChasanoffHeart Institute, Long Island Jewish Medical Center, New Hyde Park, NY 11042.

Copyright© 1994 by the American Society ofEchocardiography. 0894-7317/94$3.00 + 0 27/1/51212

182

Table 1 Echocardiographic views obtained

Echocardiographic view

Subcostal

Parasternal short-axis Parasternal R V inflow Modified parasternal R V

inflow Apical four-chamber

Structures visualized

IVC, IVC-RA juncture, SVC-RA juncture

High RA, TV, RV outflow tract TA, TV and annulus, RV RVapex

RA, TV, RV apex

IVC, Inferior vena cava; R V, right atrium; SVC, superior vena cava; TV, tricuspid valve.

performed. In the following three patients the right groin was prepared and anesthetized with 2% lido­caine, and two venous sheaths were inserted. After obtaining venous access, two steerable 6F, four-polar electrophysiologic catheters were advanced under echocardiographic guidance through the inferior vena cava (three patients) or the superior vena cava (one patient). If the catheter met with resistance dur­ing advancement, it was withdrawn slightly, re-an­gled under echocardiographic guidance, and re-ad­vanced.

Multiple echocardiographic views were obtained in each patient (Table 1). The subcostal view was used to visualize catheters in the inferior vena cava and at the inferior vena caval-right atrial juncture (Figure 1). Standard parasternal short-axis views were used to visualize the high right atrium, tricuspid valve, and R V outflow tract. Standard parasternal R V inflow views were used to visualize the region

Journal of the American Society of Echocardiography Volume 7 Number 2 Lee et al. 183

Figure 1 Standard subcostal view. Catheter (arrows) was advanced from inferior vena cava (IV C) into right atrium (RA).

Figure 2 Modified parasternal R V inflow view. Quadripolar catheter was advanced from right atrium (RA) across tricuspid valve (tv) toward right ventricular apex (R V). Four pacing and recording poles of catheter are visualized in this view (arrows) .

of the tricuspid valve and annulus. Modified R V in­flow views, or the standard apical four-chamberview, allowed visualization of the catheter tip in the R V apex (Figure 2).

The echocardiographic views were obtained and analyzed in real time, with the echocardiographer present in the electrophysiology laboratory. Thus

echocardiographic visualizations of catheters were performed during catheter manipulation by the elec­trophysiologist, with both the echocardiographer and the electrophysiologist viewing the catheters si­multaneously. This approach facilitated rapid and ac­curate visualization of the tip of the catheter (Fig­ure 3).

184 Lee eta!. Journal of the American Society of Echocardiography

March-Aprill994

Figure 3 Standard parasternal RV inflow view. Right atrium (RA) and right ventricle (R V) are visualized. Catheter tip (tip) is visualized as tricuspid valve (tv) is crossed.

Mter catheter positioning was ascertained, stan­dard electrophysiologic testing was performed in­cluding assessment of sinus node recovery times and sinoatrial conduction times, atrioventricular-nodal W enckebach cycle length and refractory intervals, His-ventricular conduction, ventricular refractory in­tervals, and ventriculoatrial conduction, after which induction of tachycardia was attempted at one ven­tricular site (two patients) or multiple ventricular sites (two patients).

CASE REPORTS

Case l

S.R. is a 19-year-old pregnant woman admitted to the hospital after a syncopal episode, with a Wolff-Parkinson­White pattern on her electrocardiogram. To determine her risk from arrhythmia, the patient underwent electrophys­iologic testing with echocardiographically guided catheter placement. Two electrophysiologic catheters were inserted percutaneously into the right femoral vein, and the cath­eters were advanced through the inferior vena cava by the subcostal echocardiographic view. Advancement into the right atrium was guided by the subcostal, and parasternal short-axis views. Catheters were placed in the high right atrium by the parasternal short-axis view. Catheters were placed in the RV apex by the modified RV inflow view. Visualization of catheters near the His bundle and crossing the tricuspid valve was obtained with the standard R V inflow view. Catheters were placed at the level of the R V outflow tract by the standard parasternal short-axis view.

The patient had a normal conduction system and was de­termined to be at low risk for Wolff-Parkinson-White syn­drome.

Case 2

G.W. is a 32-year-old woman in her first trimester who was seen with sustained ventricular tachycardia. Results of echocardiography, exercise stress test, and signal-averaged electrocardiography were normal. Two-dimensional echo­cardiography was used to guide catheter placement during intracardiac electrophysiologic testing of the right side of the heart. Two electrophysiologic catheters were inserted percutaneously into the right femoral vein and the catheters were advanced through the inferior vena cava by a standard subcostal echocardiographic view. Advancement into the right atrium was guided by the standard subcostal and parasternal short-axis views. Catheters were placed in the high right atrium, the R V apex, and near the His bundle and the tricuspid valve by the apical four-chamber view and parasternal short-axis view at the level of the R V out­flow tract.

After catheter placement, ventricular tachycardia was in­duced by extrastimulus testing. Repeat echocardiograph­ically guided electrophysiologic testing with combination mexiletene and procainamide therapy revealed that the pa­tient was noninducible. She had no further spontaneous episodes of ventricular tachycardia. A cesarean section was performed at term and a healthy male infant was delivered uneventfully.

Case 3

L.M. is a 42-year-old woman who was admitted to the hospital after a syncopal episode. The patient's last men­strual period was 19 days before her admission. An early

Journal of the American Society of Echocardiography Volume 7 Number 2

pregnancy could not be ruled out because of the window period in which the standard pregnancy test may be falsely negative. 1 The patient underwent electrophysiologic test­ing by echocardiographically guided catheter placement, through an antecubital vein cutdown. The parasternal and apical views afforded adequate visualization of the cathe­ters. The patient had a normal conduction system study and no inducible arrhythmias. The patient was discharged from the hospital with a cardiac event recorder, which revealed transient, spontaneous complete heart block re­quiring permanent pacemaker implantation. The pace­maker was implanted with standard fluoroscopic imaging because it had been determined at that time that the patient was not pregnant.

Case4

T.M. is a 21-year-old woman admitted to the hospital after a presyncopal episode in the first trimester of preg­nancy. She had previously had several syncopal episodes. Echocardiography, signal-averaged electrocardiography, and stress testing were normal, and blood test results for Lyme disease and sarcoidosis were negative. The patient underwent electrophysiologic testing by echocardiograph­ically guided catheter placement. Subcostal views afforded visualization of the catheters in the inferior vena cava and right atrium. Modified parasternal views assisted catheter placement across the tricuspid valve into the R V apex and outflow tract. The patient was found to have a normal conduction system study and no arrhythmias were in­ducible.

DISCUSSION

Although two-dimensional echocardiography has been used previously to guide electrophysiologic test­ing, there are no reports of echocardiographically guided electrophysiologic testing used specifically for consideration of pregnancy. 2 Permanent pacemaker implantation in a pregnant woman has been reported with the guidance of the electrocardiogram and two­dimensional echocardiography. 3 Transesophageal echocardiography has also been used to guide cath­eter placement during radiofrequency catheter abla­tion and to guide insertion of a physiologic pace­maker in early pregnancy. 4•

5 These studies revealed the utility of echocardiography in visualizing cath­eters.

There are several advantages of using echocardi­ography to guide catheter placement. Echocardiog­raphy enables visualization of the position of the catheters in relation to the heart structures on the right side. Other benefits of echocardiographically guided electrophysiologic study include the ability to assess complications associated with catheter place­ment such as pericardia! effusion caused by perfo-

Lee et al. 185

ration of the R V free wall and perforation of the ventricular septum. Echocardiography was judged to be better than fluoroscopy in guiding catheters in one study because of its ability to detect complica­tions as they arose. 2

At our institution, echocardiographically guided electrophysiologic ~esting has been performed suc­cessfully in all pregnant patients in whom the pro­cedure was attempted (four attempts and four suc­cesses, to date). One potential problem that may be encountered is advancement of the catheter from the iliac vein or antecubital vein into the vena cavae. Although echocardiography was used to guide the catheters once they entered the great veins, the ad­vancement from the site of insertion to the inferior vena cava (three patients) and superior vena cava (one patient) was performed blindly. It is likely that cath­eter advancement was facilitated by three factors. First, the patients were young, healthy women and likely had less venous tortuosity in the smaller veins. Second, the plasma volume of pregnant women is expanded, again decreasing the likelihood of becom­ing obstructed by venous tortuosity. Third, the use of a flexible, deflectable-tip catheter allows for easy passage even in the setting of venous tortuosity, be­cause the tip of the catheter loops over and usually follows the largest open pathway up 'toward the vena cavae. With this technique, the catheters were ad­vanced easily in all patients, without the need for a luminal catheter with a guide wire.

Previous authors have suggested that echocardi­ography is of limited utility for guiding catheter placement because of inability to visualize the cath­eter tip. With our approach, the catheter tip is vi­sualized easily during electrophysiologic testing. Two factors may make this possible. First, the echo­cardiographic views are analyzed in real time. Thus the echocardiographer is communicating informa­tion about catheter location to the electrophysiolo­gist as catheter manipulation is being performed. Sec­ond, the presence of four metal poles at the end of the catheter makes the tip more echogenic than the body of the catheter. Thus although in the past there has been uncertainty as to whether echocardiography actually demonstrates the tip of the catheter, in these four patients, when the echocardiographic image re­vealed tip contact with the tissue, excellent electro­grams and pacing thresholds were obtained. This suggests that, at least with a 2 mm metal tip electrode, echocardiography may be used to identify the tip and judge tip-tissue contact.

Use of real-time echocardiographic image analysis and emphasis on the echogenic segment of the cath­eter allow rapid and accurate determination of cath-

186 Lee et al.

eter tip position. Thus once advanced into the right side of the heart, catheters are easily positioned at all of the standard electrophysiologic positions.

In view of the ease and safety of echocardiograph­ically guided catheter placement, it is preferable to

fluoroscopy during electrophysiologic testing in ptegnant women. The use of echocardiography for catheter placement should also be <:onsidered in chil­dren and women of childbearing age, because ade­quate protection from radiation mlly not always be achieved during fluoroscopy.

REFERENCES

l. Flood JT, Hodgen GD. The physrology of fertilization, im­plantation, and early human development. In: Scott JR, DiSaia PJ, Hammond CB, Spellacy WN, eds. Danforth's obstetrics

J oumal of the American Society of Echocardiography March-April 1994

and gynecology. 6th ed. Philadelphia: JB Lippincott, 1990: 86-7.

2. Drinkovic N. Subcostal echocardiography to determine right ventricular pacing catheter position and control advancement of electrode catheters in intracardiac electrophysiologic studies. Am J Cardiol1981;47:1260-5.

3. Gudal M, Kervancioglu C, Oral D, et al. Permanent pacemaker implantation in a pregnant woman with the guidance of ECG and tWo-dimensional echocardiography. Pacing Clin Electro­physioll987;10:543-5.

4. Goldman AP, Irwin JM, Glbver MU, Mick W. Transesopha­geal echocardiography to improve positioning of radiofre­quency ablation catheters in left-sided Wolff-Parkinson-White syndrome. PACE Pacing Clin Electrophysiol 1991;14:1245-50.

5. Jordaens LJ, Vandenbogaerde JF, Van deBruaene P, De Buy­zere M. Transesophageal echocardiography for insertion of a physiological pacemaker in early pregnancy. Pacing Clin Elec­trophysiol 1990;13:955-7.