17 Transseptalpuncture
TedFeldman and WestbYG. Fisher
. Introduction . Technique . Fluoroscopic and intra-cardiac echocardiography guidance . tndications, contraindications, and complications ' References
INTRODUCTION Mullins sheath for the Brockenbrough catheter was the last major advance in the basic proce- The technique of transseptal puncture was dure. Subsequently, the transseptal puncture to gain access to the left atrium (LA) developed procedure has undergone only minor modifica- for pressure measurement. Methods to measure tions (Fig. 1) (14,15). pressure prior to the transseptal left atrial Due to the technical challenges and the risks included direct left atrial puncture approach involved with transseptal puncture, pulmonary the anterior chest wall, and trans- through wedge pressure (PCW) measurement has been bronchial puncture via the left mainstem accepted as a surrogate for left atrial pressure (1-B). These methods had obvious bronchus assessment (16). PCW measurement remains the limitations. The transseptal approach was first most common approach for estimation of the left described by Cope tn 1959, using a \7-gauge atrial pressure in patients with heart failure and needle introduced through polyethylene solid valvular heart disease. There are clear limita- tubing via the right femoral vein (9). He employed tions to PCW, especially among patients with the procedure in two patients and described left pulmonary hypertension (17-21). In the setting atrial and ventricular pressure measurement of pulmonary hypertension, elevated Pul- and angiography. In 1958 Ross et dL, while "contaminate" monary artery pressure may the working at the National Institutes of Health, wedge pressure waveform and result in a sig- were catheterizing the LA in patients with atrial nificant overestimation of the PCW. Similarly, septal defects. Ross was a feliow at the time. A . over-wedging may yield an underestimation. visiting physician observed this procedure and Methods for retrograde catheterizatron of the asked whether Ross had considered using a LA via the left ventricle have been deveioped needle to puncture the intact septum. This using specialized catheter shapes (22-24). Shirey rapidly led to the development of a needle device and Sones described a multipurpose-type for transseptal puncture via femoral cutdown in catheter that could be folded in the left ventricu- the animal laboratory (10). A few years later, lar apex and introduced into the left atrium (22). when the Seldinger technique was introduced, a This approach is complicated by frequent surgical resident working with Braunwald ventricular ectopy, ventricular perforation, and designed a catheter, the Brockenbrough catheter, inconsistent ability to cannulate the left atrium. through which the Ross needle could be placed Stefanadis et al. developed a guide catheter with percutaneously (11-i3). The substitution of the a pull wire to flex the catheter tip backward from 204 FELDMAN AND FISHER
Figure1 Mullinssheath and transseptal needle. The left panelshows 2 brandsof S-FrenchMullins sheaths. The curvehelps direct the tip of the sheathtoward the left ventricleafter placementin the left atrium.The inset showsthe tip of the transseptalneedle protruding from the end of the dilator-sheathassembly. The right panelshows the hub of the dilator,sheath, and needleassembly. The largemetal arrow indicates the orienta- tion of the curveof the tip of the needle.A styletis placedwithin the needleas the needleis passedthrough the dilatorinitially, to keepthe tip of the needlefrom catchingor perforatingthe transseptaldilator and sheath duringinsertion of the needle.
the left ventricle toward the LA, which allows distal end of the transseptal dilator. The needle is introduction of a wire consistently and reliably positioned with its tip a few millimeters proximal into the left atrium (25). This device is not avail- to the distal end of the Mullins dilator, connected abie in the United States and has not gained to a manifold and flushed (Fig. 2, inset). Right wide popularity for diagnostic purposes, being used only for retrograde, transarterial mitral balloon valvuloplastv. Thus, transseptal puncture remains the gold standard for left atrial pressure assessment. It has clearly become more important in both elec- trophysiology and interventional cardiology as therapeutic procedures that require left atrial accessbecome more common (21).
TECHNTqUE
The basic technique involves right femoral vein access.A 0.032in. small guide wire is passed into the superior vena cava. A pigtail catheter is piaced in the aortic root to better define the loca- tion of the aortic valve. A Mullins sheath and dilator are tracked over the wire into the superior vena cava and ideally angulated toward the left subclavian vein (Fig. 2). The wire is removed. A Figure2 The initialstep in the transseptalproce- transseptal needle is introduced into the dilator. dure is placementof the dilatorand sheathin the The needle contains a stylette that keeps the tip superiorvena cava (SVC). A 0.025in. or 0.032in. of the needle from catching on the body of the wire is placedin the SVC.The insetshows the tip of transseptal sheath dilator as the needle is the transseptalneedle placed just withinthe end of advanced. The stylette must be withdrawn from the dilator(arrow). Abbreviations: RA, right atrium;RV, the needle before the needle gets too close to the rightventricle; SVC, superior vena cava. TRANSSEPTALPUNCTURE 205 atrial pressure is recorded from the tip of the septum spontaneously at that point and the left needle. The needle and sheath/dilator assembly atrial pressure will be seen. If this is not the case, are pulled caudally through the superior vena pressure will damp as the needle tip contacts the cava (SVC) toward the right atrium (RA) as a unit. interatrial septum. The transseptal needle is There is an indicator arrow on the hub of the advanced out from the tip of the transseptal needle that shows the direction of the angle of the dilator. The needle must be advanced forcefully needle. As the entire apparatus is pulled inferi- to avoid simply pushing the fossa away in front orly from the SCV the needle and Mullins sheath of it. The fossa ovalis comprises roughly 25"h to are rotated as a unit clockwise until the indicator 30% of the total septal area and is usually the arrow points inferiorly to between the 4 o'clock thirurest portion of the septum. The diameter of and 6 o'clock position (Fig. 3). The degree of rota- the fossa can vary dramatically from patient to tion is less in structurally normal hearts, and pro- patient. This membrane consistency varies, gressively more in aortic stenosis and mitral vaive however, usually becoming thicker and more disease. The fossa ovalis lies in the posterior fibrotic with age. The fossa may extremely thick- aspect of the intra-atrial septum and is bounded ened after prior cardiac surgery. When the needle superiorly by the limbus, an arch shaped outer enters the LA,left atrial pressure is recorded, and muscular rim. Classic descriptions note two right- the dilator can be advanced into the LA and the ward movements as the needle is withdrawn needle withdrawn. Perforation of the LA posteri- from the SVC to the RA. The needle can be felt to orly or anteriorly tpith the needlealone has rarely move over the aortic knob, and then drop into the resulted in significant cardiac complications. It is fossa ovalis (Fig. a). The first movement over the typically the dilation with the sheath dilator or aortic knob is often difficult to appreciate or sheath itself that can cause significant cardiac absent. When the needle and dilator are in place compromise. If there is aortic or pericardial stain- on the fossa ovalis, it usually appears that the ing"foilowing what is presumed to be transseptal curve of the Mullins sheath wili directly puncture puncture, the needle must be removed and the the aorta. If the image intensifier is moved from dilator withdrawn and then the 0.032in. J wire an anteroposterior view to either a right or far left repositioned to the SVC and the process repeated. anterior oblique, it is possible to see that the When the needle is clearly in the LA, the sheath needle is pointing posterior to the aorta (Fig. 5). can be advanced over the dilator and needle to A slight forward pressure on the needle will secure accessin the LA. Free back-bleedi^g of arte- engage or catch on the lirnbus of the fossa ovalis. rial blood should be noted from the hub of h'r many cases,the dilator will cross the intraatrial the Mullins dilator. Any air bubbles must be
Figure3 The arrowindicator (lower arrow)on the transseptalneedle is orientedtoward about 4 or 5 o'clock,rel- ativeto the patient.The patient'shead is on the left side of the picture,and the feet are on the right.The transseptal needleis shownattached to a manifold for pressuremeasurement. In the upper left cornerof the picture,a second white arrowshows the rightatrial pressure, dis- playedon the monitor. 206 FELDMAN AND FISHER
(D) tE) (F)
Figure4 The basicsteps in the transseptalprocedure. (A) The sheath,dilator, and needlehave been placed in the superiorvena cava. (B) The sheath,dilator, and needleare pulleddown inferiorlyover the bulgeof the aorta.(C) The assemblyhas engagedthe fossa ovalis.The indicatorarrow is rotatedto between4 and 6 o'clockrelative to the patient.(D) The needlehas beenextended out of the dilator,through the fossa ovalis into the left atrium.Left atrialpressure should be seen on the monitor.(E) The dilatorhas been advanced overthe needleinto the left atrium.(F) A wire is advancedinto the left upperlobe pulmonaryvein, and the sheathadvanced over the dilator.The sheathand wire are carefullyremoved to avoidaspiration of air,and the sheathsystem flushed. Heparin is administeredat that point.
aspirated. Contrast injection can be used to verify the procedure. Percutaneous mitral valve repair the position of the Mullins sheath within the LA or longer electrophysiology procedures require (Fig. 6). It is useful to pass a guidewire through activated clotting times > 300 seconds. the dilator just after the needle has been removed The left femoral vein is usually not a success- to stabilize forward advancement of both the ful approach, since the angulation of the left iliac dilator and the sheath. One of the disappointing vein as it joins the inferior vena cava wili force modes of failure for this procedure is to success- the transseptal needle to move away from the fully puncture the septum, but then have the tip intra-atrial septum. Only in patients who are of the dilator jr-p forward and perforate the left very narrow hipped with a steep angle between atrial free wall. Using a wire to help pass the the iliac vein and the inferior vena cava may left dilator and sheath across the intra-atrial septum femoral accessbe likely to succeed. thus makes advancing the dilator safer.After suc- Measurement of pressr-lre through the cessfui puncture of the intra-atrial septum, transseptal needle is not a uniform practice. In heparin is given. The heparin dose depends on our opinion, it is essential for the safest method the purpose of the procedure. For a diagnostic for accessing the LA. If the needle is advanced procedure where the catheter time in the LA and LA pressure is not detected, a number of would be very brief, an arbitrary smal1 dose of possibilities exist. The needle may be buried in heparin might be used. For procedures such as the tissue of the septum, having taken a tangen- valvuloplasty, activated clotting time between tial through the septum. It is possible that the 200 and 300 seconds is desirable, depending on free wall of the roof of the RA or the inferior TRANSSEPTALPUNCTURE 207
Figute5 The panelshows /eft an anteroposterior(AP) view. The arrow points atthe tip of the dilator,from whichthe needle is extendedinto the left atrium.the right panelshowsa rightanterior obtique (RAO) view. The arrowagain indicatesthe tip of the dilator,from whichthe needleextends. The pigtailcatheter is resting againstthe aorticvalve. On the APview it appearsthat the needlehas transectedthe aorta,while on the 30" rightanterior oblique view it is clearthat the needleoverlies the spine,and is thus posteriorto the aortaand pigtail.
border of the RA or LA has been perforated. It is also possible that the LA has been entered, but that a small thrombus has occluded the pressure lumen of the needle. In any of these eventuali- ties, as long as the needle is withdrawn and the B-French sheath is not advanced, and as long as the patient is not anticoagulated, the poter*ial for pericardial tamponade is small. AJ long as the_incorrectposition of the needie is recognLecl and the attempt abandoned at that point, com- plications from needle perforatiorJ ur" infre- quent. This emphasizes the need to have patients off of coumadin or heparin anticoagll- lation prior to beginning a transseptal puncture procedure.
FLUOROSCOPICAND INTRA.CARDIAC ECHOCARDIOGRAPHYGUIDANCE Figure6 Contrastinjection after successful transseptalpuncture. The white arrowheadsmark Since fluoroscopy only allows indirect assessment the upperborder of the left atrium; the white arrows of the location of the fossa ovalis without good mark the intra-atrialseptum; the btack arrowheads visuai representation of these critical anatomic showthe mitral valve,closed in this angiographic landmarks, advancement of the transseptal frame. needle using only fluoroscopically-guided iechniques 208 FELDMANAND FISHER can be freqr,rently associated with unpredictable A iong acquisition time is required to be able to outcomes. The introduction of intracardiac see the left atrial filling on the levo phase. echocardiography has added greatly to the safety More recently, intravascular ultrasound has and appreciation of the anatomic variability and become the method of choice to clearly visualize location of fossa ovalis. Some centers routinely the atrial septum to assist in transseptal puncture perform transesophageal echocardiography to (26-3I). Intracardiac echo (ICE) is widely avail- facilitate kansseptal catheterization. Trans- able. A relatively simple ICE catheter is available esophageal echocardiography can readily image which uses a single rotating crystal ultrasound the fossa ovalis and needle assembly,but requires transducer based on either 9-French 9MHz rotat- a second operatoq, greater degrees of sedation, and ing crystal or a 6.5-French 12.5MHz ultrasound is not practical for long procedures. More recently, crystal (CVIS@, Boston Scientific, Sunnyvale, intracardiac echocardiography has been employed CA). This has the advantages of being compati- to facilitate transseptal catheterization. With the ble with standard coronary intravascular ultra- introduction of this technology, a single operator sound consoles, and it is relatively inexpensive, can perform this procedure painlessly and contin- costing about the same as a coronary IVUS uously without sedation. Intracardiac echocardio- catheter. It has the disadvantages of a limited graphy has permitted less experienced transseptal depth of field, and it provides no more than a operators to adopt the procedure. planar 2-dimensional view of the atrial septum. The classic approach to transseptal puncture Nonetheless, in many cases it is adequate to uses fluoroscopic guidance coupled with tactile demonstrate contact of the transseptal needle feedback from the dilator. The location of the with the fossa ovalis. Accuson, a 64-element "guestimated" puncture is based on the location phased-array ultrasound system using a 10- of the aortic root as marked by u pigtail com- French gMHz transducer (AcuNav@, Seimens bined with bony landmarks. The variability of Acuson, Mountain View, CA) that images in a the puncture location is extreme. The classicflu- sector field oriented in the plane of the catheter oroscopic landmark for the puncture site is in rather than a circumferential fieid of view intrac- the center of the spine, at the level of the aortic ardiac echo, requires a Siemens echo machine root. Depending on the patient's age,the relative console, and the catheters are significantiy more amounts of right and left atrial dilatation, and expensive than the simple Boston Scientific ultra- spinal deformities, the puncture site may fre- sound. They have the advantage of a greater quently be to the left or right of the center of the depth of field, image quality that appears basi- spine, sometimes by many centimeters. Tactile cally equivalent to transesophageal echocardiog- feedback from the transseptal needle is one of raphy, and the availability of color Doppler as the most important descriptors of the location of well. Accuson ICE is used widely in conjunction the puncture. As the dilator is withdrawn from electrophysiology ablation procedures and with the SVC and felt to catch on the lumbus with a shunt closure procedures, because in addition to slight forward motion, a pulsatile motion can be verifying catheter placement, it aids with device felt in some cases. If fluoroscopy shows the placement and assessment of post-procedure neeclle pointing posterior and away from the shunting. "septal aorta, the pulsatility represents the atrial \\rhen the transseptal dilator engages the fossa, bounce," whereas if the needle is pointing at the it causes a puslling or tenting of the fossa from the aorta, it is the aorta that is being feit. Advance- RA into the LA (Fig. 7). It is important to note that ment of the needle will yield a left atrial pres- the tip of the transseptal needle itself is often echo- sure tracing, which confirms the left atrial lucent and tenting is the only reliable sign of location. proper engagement of the fossa ovalis. Simply A variety of methods can be used to determine seeing the echo shadow of the catheter close to the the location of the center of the intra-atrial septum canbe highly deceptive, since the body of septum. One of the simplest is right atrial contrast the transseptal catheter may be transected by the injection with filming of the levo phase. Contrast plane of the ultrasound beam even when the tip of 20 or 30 mL can be given as a bolus in the RA. of the needle is far away from the septum. TRANSSEPTALPUNCTURE 209
Figure7 Intracardiacecho guidance for transseptalpuncture. The left panelshows a baselineimage. The arrowheadsshow the intra-atrialseptum (lAS). In the righthand panelthe transseptalneedle has beenengaged in the foramenovale; the arrowshows tenting of the intra-atrialseptum into the LA causedby forwardpressure of the transseptaldilator. There is considerableshadowing in the left atriumfrom the transseptalapparatus. lt is notablethat the needleitself is not visible,but that the tentin$is welldisplayed, The needleis eitherout of planeor, because of its relativelythin structure,is in this frame echolucent.Abbre- viations:RA, right atrium; AO, aorta; LA, left atrium.
The fluoroscopic views are adjusted so the His The electrophysiology approach bu4dle catheter is pointing directly at the image A totaliy venous accessapproach to transseptal intensifier of the fluoroscopic camera. The right procedures is now commonly utilized in experi- anterior oblique angulation is adjusted so the enced electrophysiology (EP) laboratories. coronary sinus catheter intersects the His bundle Because EP catheters are placed in strategic catheter and its midpoint. Careful evaluation of anatomic locations defined by their recorded the His bundle recording should be maintained to electrograms, EP recording equipment is ensure an accurate anatomic reference relative to required. It is our practice to begin by placing a the inferior aspect of the aorta. The transseptal His bundle and coronary sinus catheter to needle and sheath assembly are withdrawn in the provide anatomic landmarks fluoroscopically LAO view as a single unit matntaining the position (Fig. 8). A His bundle catheter thot is recording a of the needle to the dilator from the SVC position His btmdle always identifies the most inferior to the RA with the needle usually oriented in the aspect of the non-coronary cusp of the aorta. 4 o'clock psosition. If the coronary sinus catheter This obviates the need for an arterial puncture has been placed from a superior approach, care to place a pigtail catheter in the ascending aorta. must be utilized to ensure that, during torquing of A coronary sinus catheter properiy placed along the sheath, the coronary sinus catheter is not the artereovenous groove demarcates the widest fwisted around the sheath and needle assembly. portion of the LA parallel and just posterior to As the needle/sheath assembly is withdrawn, the mitral annulus. One must ensure that the an initial slight leftward jr*p of the assembly is coronary sinus catheter courses near the mitral noted as it enters the RA, and then a second annuius by seeing equal-amplitude atrial and movement leftward occurs as the catheter tip ventricular electrograms exist throughout the approaches the level of the His bundle catheter, course of the catheter. If not, the catheter may which is below the superior limbus of the fossa have inadvertently been piaced in a posterolat- ovalis. At this level the RAO view confirms that eral branch of the coronary sinus and should be the catheter tip is posterior to the site of the His repositioned prior to performing transseptal bundle recording and angled posterior and par- catheterization. aliel to the projection of the coronary sinus 210 FEI,DMAN AND FISHER
Figure8 (A) RAO40 and LAO40 fluoroscopicimages of the sheath, dilator,needle assembly positioned in the superiorvena cava.Note the positionof the His bundlecatheter (His),coronary sinus catheter (CS), and intracardiacechocardiography catheter(lCE). (B) Angulation of the RAOcamera is adjustedto 30 degreesso the proximalelectrode of the His catheteris in the same verti- cal planeas the CS catheter(dashed white line in RAOview). Withdrawal of the sheath/dilator/needle (SDN) has enteredthe rightatrium. Note the assemblyis positionedtoo posterio- rallyin the RAO3O-degree view despitehaving the needletorqued to approximatelya 4 o'clockposition. (C)Proper positioning of the SDN positionprior to transseptalpunc- ture. Notethe SDNassembly is ori- entedposterior to the His bundle catheterin the RAOview. Note that the electrogramsof the His bundle must be seento be ableto usethis catheteras a reliableanatomic land- mark.Typically, the tip of the dilator is at the same levelas the His bundlecatheter (solid white line)and well to the left (posterior)of the His bundlecatheter in the LAOview, and posterior parallel '', oriented and to the CS catheterin the RAOview. (D) Sheathposition following transseptal crossing.Following transseptal punc- ture the dilatoris advancedover the needleand dilatorassembly into the left atrium.Only after the sheathis advancedinto the left atriumshould the needleand dilatorbe removed, '.'ryq becausethey providesupport for the pass '::;i:;1 sheathto intothe left atrium. The pointof transseptalcrossing is markedbv an "x", TRANSSEPTALPUNCTURE 211 catheter. This angle ensures that the assembly is assembly to enter the LA and, with the sr-rpport not pointing too posteriorally, in which case the of the needle, the sheath is advanced over the needle may perforate the posterior wall of the dilator into the LA. If there is any question about LA, and not pointing too anteriorally, at which the location of the needle the diiator should not point the needle might enter the ascending be advanced. Once the sheath is in the LA and aorta. Adjustments of angulation between 3 has been flushed, heparin is given. o'clock and 6 o'clock may be necessary, with enlarged left atria often requiring a more poste- Thickened atrial septum rior (or 5 to 6 o'clock) angulation and vertically oriented hearts requiring a more anterior (3 to 4 A septum thick enough to make puncture diffi- o'clock) angulation of the needie. cult may be encountered in oider patients with When the anguiation of the needle is con* lipomatous hypertrophy and after prior oPen firmed, transseptal crossing is done in the LAO heart surgery (31-36). Patients with prior valve projection. The assembly is withdrawn. 25-.5 cm surgery may develop endocardial thickening, farther and then advanced to engage the limbus and in some casesthe fossa is sutured to prevent of the fossa ovalis. Patients with patent foramen air embolism. Puncture may also be performed ovale will have the dilator move toward the left after atrial septal patching or repair for congen- atrium. If hemodynamics are utilized, the left ital heart disease. In all of these situations ICE is atrial pressure recording can be recorded from extremely heipful and puncture is often unsuc- the transseptal needle or the needle location can cessful without ICE guidance (Fig. 9). The needle be confirmed by ICE or contrast injection. More may be advanced tangentially into the septal commonly, however, the dilator does not pass tissue, so that even if the puncture location is spontaneousiy into the left atrium. Pressure correct, it is not possible to reach the LA. When "tenting" measurements are usually damped when the the'transseptal needle causes of the needle and dilator are juxtaposed to the intra- septum, more force than is otherwise acceptable atrial septum. When the transseptal needle is can be used to advance into the LA. Another "poP" advanced to enter the LA, a tactiie is felt. method to cross a t'ough or thick septum is with This can be confirmed by contrast injection or radiofreqlrency perforation (37). This requires pressure recording from the tip of the needle. specialized equipment, and is best per:formed The dilator is then advanced over the needie with ICE.
Figure9 lntracardiacecho images from a patientwith a markedlythickened intra-atrial septum. This patient had undergoneprior resection of a rightatrial myxoma from the risht atrialfree wall.The septum is almost l--cm thick.The /eft panelshowstenting of the septumfrom a transseptaldilator marked by the arrow.With full exten- sionof the needle,the left atriumcould not adequatelybe entered.Fonrvard pressure on the needle,more extremethan wouldbe possiblewithout echo guidance, was necessaryto forcethe needleinto the left atrium, and ultimatelyrecord left atrialpressure via the needlebefore advancing the dilator.\he right panelshowsthe needleacross the septum,marked by the arrowhead.Abbreviatlon: LA, left atrium. 212 FELDMAN AND FISHER
simultane- Indications, contraindications' and into the left ventricle (Fig. 10). Thus can complications ous left atrial and left ventricular pressure be obtained via a single venous puncture lndications without the need for arterial catheterization or Similarly, Indications for transseptal procedures include a retrograde crossing of the aortic valve. meas- variety of diagnostic uses, and an increasing this approach for left ventricular pressure place- affay of therapeutic procedures (35-39). Diag- ,-tre-ettt can be coupled with retrograde aorta for nostic assessment of mitral and aortic valve ment of a catheter in the central valve disease, congenital lesions, and hypertrophic accurate assessment of the transaortic or hyper'- cardiomyopathy are the most frequent situations pressure gradient in aortic stenosis yields in which transseptal puncture is employed' irophic cardiomyopathy. This method either side of Mitral stenosis is, of course, the most classic, and pressures recorded directly from artifacts of pres- catheter-based mitral valve repair the most ihe valve and avoids all of the that are recent (39). Direct measurement of left atrial sure amplification and damping sheath substitu- pressure combined with retrograde left ventric- common in peripheral arterial when assess- Llut pt"tsure yields accurate assessment of the tion for the central aortic Pressure transmitral pressure gradient. It is also possible ing aortic valve stenosis. approach has to pass a French Mullins sheath into the LA, and i., tut" instances, the transseptal into the aortic root through this float a 7-French balloon tip catheter been used to pass a catheter
puncture.This is an excel- Figure1o catheterizationof the left ventriclevia the mitralvalve after transseptal case,the patienthas a teit methodto recorda transaorticor transmitralvalve pressure gradient' In this of Valsalvaadjacent to the Hancockbioprosthetic aortic valve replacement. A pigtailcatheter sits in the sinus A 7-Frenchsingle lumen balloon valvein the left panel(Apview). The arrow marks the tip of the Mullinssheath. balloonis markedby the catheterhas beenfloated across the mitralvalve into the left ventricle.The inflated has beensubstituted for the arrowheadIn the right handpanelin a rishtanterior oblique view, a pigtailcatheter left atrialand left ventricular singlelumen balloon catheter for ventricuiograpny.Simultaneous recording of the pressuresfor evaluationof the pressuresfor evaluationof mitralstenosis, and of the left ventricularand aortic pigtailcatheter is just visiblein transaorticvalve pressure gradient can be easilyaccomplished. A centralaortic LV left ventricle' the upperleft cornerof this frame.Abbreviations: RA, right atrium; LA, Left atrium; TRANSSEPTALPUNCTURE 213 for coronary arteriography. This can be accom- Contraindications piished in patients with limited access from the The most important contraindications to extremities. It, of course, requires a great deal of transseptal puncture include atrial thrombus or catheter manipulation and time to achieve selec- mass. Right atrial thrombus may form on pace- tive or semiselective coronary arteriography. maker leads or inferior vena cava filters. It is The method for access of the aorta via the unusual for right atrial thrombus to directly pre- transseptal route is used increasingly for thera- clude transseptal puncture. Left atrial appendage peutic procedures but also has diagnostic utility. thrombus is a more common problem (Fig. 12). A 8-French transseptal sheath is placed in the In mitral stenosis patients who have not been on LA. A 7-French balloon catheter is floated into coumadin, left atrial appendage thrombi will the left ventricle. The catheter can be curved in often resolve in 2 to 4 months with coumadin the left ventricular apex, or a curved wire can be therapy. For patients who have been on introduced into the catheter to help it make the coumadin, the addition of antiplatelet therapy turn around the apex, and then the balloon and more intense coumadin therapy is sometimes catheter is floated across the aortic valve into the successful. Smoke, or spontaneous echo contrast, aortic root. This allows measurement sequen- in the LA is not a contraindication to transseptal tially of the entire right and ieft heart circula- puncture. Rare cases of atrial septal thrombus tions, or passage of a guidewire from the RA, are encountered and represent an important across the septum into the LA, through the left contraindication to transseptal puncture. In ventricle, into the aotta, and sometimes out cases where left atrial appendage thrombus is through a femoral arterial sheath. This trans- "floss- seen on a baseline echo, and then appears in a circulatory wire loop is sometimes called stable concave, echo-dense (organized) configu- ing" the circulation (Fig. 77) (21,36). ration on a follow-up echo after prolonged anti- Therapeutic uses for transseptal catheterization coagulation therapy, it is sometimes safe to are increasing rapidly. Catheter ablation for left proceed with transseptal puncture. If the atrial sided accessory pathways and atrial fibrillation in appendage thrombus is well organized, there is electrophysiology have become conunon proce- little risk of embolization. Unfortunately it is dures. Antegrade valvuloplasty of the mitral valve, prospectively very difficult to tell whether any and also of the aortic valve is accomplished using fresh or mobile thrombus might exist on the transseptal access.Paravalvular leak closure also surface of an echo-dense organized thrombus. frequently requires transseptal access either for Thus, left atrial appendage thrombus remains delivery of a closure device, or for wire passage to an important relative contraindication to this ultimately allow retrograde delivery catheter procedure. placement. The variety of new percutaneous valve Another strong relative contraindication to repair and replacement therapies require transsep- transseptal puncture is in patients who have tal puncture as well. Mitral valve repair is abnormal coagulation or thrombocytopenia. predicated on left atrial access via the transseptal Many patients present for transseptal catheteri- route. The E-valve procedure uses a 24-French zation having been on coumadin. Coumadin is venous cannula to accessthe LA, and then place a typically discontinued 3 or 4 days before the clip directly on the mitral leaflets. A great advan- catheterization procedure. A bridge using tage of the transseptal route is the ability to place heparin or Lovenox@ (Aventis, Bridgewater, NJ) large catheters in the femoral vein, and then is commonly employed. It is my practice to achieve left heart access.The obviates the need for proceed with transseptal puncture only if the iarge bore atrial sheaths in many instances. international normalized ratio (INR) is less than Antegrade aortic balloon valvuloplasty is accom- or equal to 7.7. After a hiatus off of coumadin plished using a 14-French venous sheath. This therapy, patients will occasionally appear with bears the challenges of arterial access and hemo- an elevated INR and the procedure must be stasis using sheaths of that caliber via the arterial delayed. Platelet counts of 50,000to 100,000rep- route, necessary of course for retrograde aortic resent a degree of thrombocytopenia that valvuloplasty. imposes an important risk for tamponade if an 214 FELDMAN AND FISHER
Figure11 A guidewirehas been placedvia the transseptal routethroughout the wholecirculation. This is sometimes called"flossing" the circulation.The course of the wire involvesintroduction through a transseptalsheath via the inferiorvena cava (lVC), right atrium (RA), left atrium(LA), acrossthe mitralvalve and into the left ventricle(LV), then out intothe aorticarch and the descendingaorta. ln this examplethe wirehas beensnared in the descendingaorta (arrow).The snarehas beenclosed on the wireto provide stabilityfor antegradeaortic balloon valvuloplasty. lt is also possibleto snarethe wire and exteriorizeit, whichallows introductionof devicesfrom eitherthe arterialor venous limbsof the samewire. lmportantly, when a wireloop like this is removedfrom the circulationit is criticalto coverit with a diagnosticcatheter so that frictionof the wire does not lacer- ate the heartvalves. TRANSSEPTALPUNCTURE 215
Figure12 Transesophagealechocardiographic images showing left atrialthrombus. Atrial appendage thrombus is one of the most importantcontraindications to transseptalprocedures. ln the left panel,the arrowheadsshow a largethrombus. ln Lheright panel in a secondframe, the thrombusis seento havea lobularor globularappear- ance.The thrombus extends out of the left atrialappendage (LAA) into the bodyof the left atrium(LA). Echocar- diographicsmoke is seenin the appendageand extendingout intothe bodyof the left atrium.
errant puncture results from the procedure. A the proximity of these structures. The septum platelet count over 100,000 can generally be tends to lie more horizontal in patients with left regarded as acceptable for proceeding with a atrial eniargement and can be more vertical in transseptal pr-rncture. patients with aortic valve disease or a dilated aortic root. Varying degrees of kyphoscoliosis can also alter intrathoracic cardiac rotation. Also, Complications prior open heart surgery can result in a thick- Thromboemboli from the catheter, needle, or ened fossa ovalis because surgeons occasionally cardiac chambers may occur. Extreme care to must over-sew the fossa in patients with a patent flush and wipe the transseptal system frequently foramen ovaie to ensure evacuation of air from is needed to avoid thrombus formation on the the LA before coming off cardiopulmonary transseptal needle. The stainless steel needle is bypass. Cardiac perforation may result from metai and highly thrombogenic. In most perforation of the RA, perforation of the LA after: reported series cardiac tamponade occurs in successful transseptal puncture, and also by per- 0.5-2/,, and stroke in
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