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.