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Crossing
the Mitral Valve The conventional approach employed in crossing the valve is the direct method, whereas the alternative approach is the posterior loop method. Subsequently, 2 other approaches have evolved: the sliding and the vertical methods. Currently, we attempt valve crossing using 4 methods in the order of: 1) the vertical; 2) the direct; 3) the sliding; and 4) the posterior loop method (Fig. 1). The vertical method is the most frequently successful crossing method. After deep catheter placement in the left atrium under a fluoroscopic frontal view, the crossing is conducted under a 30° right anterior oblique view, which displays the left ventricular long axis in profile (broken lines in Fig. 1). In patients |
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with
giant left atria, additional use of a lateral fluoroscopic view may be needed
to facilitate crossing of the valve. During crossing manipulations, the catheter balloon position can be controlled as the operator wishes because the vertical balloon position is adjusted by withdrawing or advancing the catheter with the left hand, while its horizontal or axial movement is controlled by a counterclockwise or clockwise twist to the stylet using the right hand (in a right-handed operator). |
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| * Coming Soon | Deep
Catheter Placement (Fig. 2) After transseptal access, the balloon catheter is introduced under the frontal view into the left atrium over the coiled-tip guide wire to form a large loop with the tip medial to the mitral orifice, pointing in the 6 to 7 o'clock direction (panel 1). This will also prevent the catheter from flipping into the left atrial appendage. The fluoroscopic projection is then changed to a 30° right anterior oblique view. With the stylet inserted into the catheter tip, the catheter is withdrawn slightly to |
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| direct
the distal catheter straight downward (panel 2). In subsequent manipulations,
the vertical balloon position is controlled by withdrawing the catheter,
while its horizontal or axial movement is adjusted with a counterclockwise
twist to the stylet using the right hand. With the stylet inserted to the catheter tip, the distal balloon is partially inflated and the balloon is directed anteriorly by applying a counterclockwise twist (usually 180°) to the stylet. The catheter is then withdrawn gradually to begin the valve crossing procedure from the vertical method (panel 3). |
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| Valve
Crossing 1. The Vertical Method (Fig. 3) The catheter is withdrawn until a horizontal bobbing motion of the balloon is noted, indicating close proximity of the balloon to the mitral valve. Upon further slight retraction of the catheter, the balloon is observed to move in (during diastole at A and C) and out (during systole) of the left ventricle (B and D) even though the catheter is not aligned with the orifice-apex axis. Coincident with diastole, only the stylet is withdrawn (E), permitting the balloon to enter into the left ventricle (F). To accomplish this, the operator must carefully watch the rhythmic motion of the heart. This allows the |
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| distal
segment of the catheter to take on a more horizontal orientation to cross
the valve and enter deep into the left ventricle. If the distal portion
of the catheter is still vertically oriented and points to the inferior
wall of the left ventricle (G), the catheter is carefully retracted to align
it with the orifice-apex axis (H). During the process, the distal balloon
may need to be inflated further to prevent it from popping out of the ventricle. 2. The Direct Method When the vertical method fails, the balloon catheter is withdrawn further until the catheter balloon is near the valve and the catheter is well aligned with the orifice-apex axis. At this time a "woodpecking" sign is observed as the balloon moves away from the mitral orifice in systole, and toward it in diastole along the axis between the mitral orifice and the left ventricular apex (the orifice-apex axis). Once this sign is evident, the balloon is in position to cross the mitral orifice. With careful attention to the rhythmic motion, the operator jerks the stylet back slightly (4-5 cm) as the balloon approaches the orifice, and simultaneously advances the catheter to drive the balloon across the valve and deep into the left ventricle. Since hand-eye coordination is vital, the beginner may choose to conduct these movements in two steps: while holding the catheter still, the stylet is withdrawn to allow the balloon to flow across the valve, and then the catheter is pushed. Because timing is critical, the selection of patients with sinus rhythm is recommended in an operator's early experiences with PTMC, as it is then easier to make use of the regular cardiac cycle to advance the balloon across the mitral orifice. |
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| 3.
The Catheter Sliding Method (Fig. 4) When the vertical or direct method fails, the catheter is withdrawn to make the distal segment more horizontal. The distal catheter is then made more flexible by withdrawing the stylet clear out of the balloon segment (A). Once the slightly inflated balloon is at the mitral orifice, cardiac contractions will cause the balloon segment to tilt upwards during systole (B). In diastole, the balloon segment aligns with the catheter shaft (A and C). This indicates proper positioning of catheter tip at the mitral orifice. With the operator carefully watching the rhythmic motion of the cardiac cycle, only the catheter is advanced forward (with the stylet kept fixed) during diastole (C) to cross the valve (D). It is |
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to note that forceful advancement of the catheter should be avoided, because
if the balloon misses the valve orifice, the balloon may enter the left
atrial appendage. After successful catheter crossing of the valve, the stylet
is then advanced to help align the catheter with the orifice-apex axis (E). The sliding method has proved to be effective in cases when the septal puncture is made too caudally and/or the left ventricle takes a more horizontal orientation (Fig. 4, top left panel). |
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4. The Posteror Loop Method (Fig. 5) Balloon catheter insertion across the mitral orifice is particularly difficult when the transseptal puncture is made too cephalic or too anteriorly (closer to the mitral valve). The loop method is useful in such cases, and also in patients with giant left atria. This method is infrequently used in our experience. First, the balloon catheter is inserted far into the left atrium to a site near the mitral valve to make a large catheter loop (A). Then, the stylet is inserted to a point 2 to 3 cm proximally to the balloon segment. With the stylet twisted clockwise, |
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| the balloon tip is brought toward the posterior and inferior wall of the left atrium. Then the catheter forms a loop in the left atrium (B). With the stylet held firmly, only the balloon catheter is advanced, allowing the balloon to move forward to the mitral orifice. In this way, the balloon catheter can be easily inserted across the mitral orifice (C). When the balloon enters the left ventricle by this method, its tip may point upward (C). The loop is then reduced by carefully withdrawing the catheter and slightly advancing the stylet the balloon (D) to align the distal catheter with the long axis of the left ventricle (E). Before dilating the valve, one has be to certain that the balloon has not strayed among tendinous chords by observing its free movement in the left ventricle (F). | ||||
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© 2002-2003 Dr. Jui-Sung Hung. All Rights Reserved.
Questions or Comments? Email shung@pipeline.com. |
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