Ann Thorac Surg 2007;84:680-682
© 2007 The Society of Thoracic Surgeons
How To Do It
Preoperative Determination of Artificial Chordae Length
Mohammad Hossein Mandegar, MD,
Mohammad Ali Yousefnia, MD,
Farideh Roshanali, MD*
Cardiac Surgery Department, Day General Hospital, Tehran, Iran
Accepted for publication November 28, 2006.
* Address correspondence to Dr Roshanali, No. 1, 8th Floor, 15th Tower, Hormozan St, Ghods Shahrak, Tehran, 14466, Iran (Email: faridehroshanali{at}yahoo.com).
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Abstract
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We present a practical and accurate way to measure artificial chordae length in mitral valve repair. During preoperative transesophageal echocardiography, the distance between the head of the posterior papillary muscle and the mitral annulus plane at the coaptation of the leaflets is measured; this is the length of the new chorda. Every millimeter of braided 4-0 Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) contains two tight reverse knots; therefore, the number of the knots determines the accurate length of the artificial chorda.
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Introduction
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The proper length of artificial chordae can be measured in such different ways as manufacturing the new chorda after measuring a nonprolapsing chorda [1], joining the anterior leaflet to the nonprolapsing posterior leaflet with a temporary suture [2], using a nonprolapsing scallop as a reference point [3], filling the left ventricle with saline [4, 5], and using perioperative transesophageal echocardiography to measure the extra length of elongated chordae [6]. Because there is no universally accepted method, we report a practical and accurate way to determine the length of artificial chordae based on preoperative transesophageal echocardiography.
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Technique
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During preoperative transesophageal echocardiography, a line is drawn between the base of the anterior and posterior mitral leaflets (ie, the mitral annulus plane) to measure the distance between the head of the posterior papillary muscle and this plane at the coaptation of the leaflets; this is our artificial chordae length (Fig 1). The point of origin of the new chorda will generally be lower than that of the one to be replaced; in other words, the new chorda is fixed below the tip of the papillary muscle. Nevertheless, because the coaptation of the mitral leaflets is roughly 3 mm below the annular plane, it is not necessary to add the distance between the point of origin of the new chorda and the tip of the papillary muscle to the length obtained by means of transesophageal echocardiography. During surgery, 4-0 Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) is passed through the fibrous tip of the papillary muscle with a pledget and is fixed with a loose knot so as to avoid necrosis. We have already established that there are exactly two tight reverse knots in every millimeter of braided 4-0 Gore-Tex (Fig 2); therefore the length of the artificial chorda having been determined by preoperative transesophageal echocardiography, the Gore-Tex is braided in as many tight reverse knots as it is required (Fig 3). The needles are subsequently passed through the edge of the anterior leaflet at the prolapsing portion, and the Gore-Tex is knotted onto a strip of pericardium so that the final knot can be placed at the atrial side of the leaflet (Fig 4). The new artificial chorda can serve as a model for the length of all the other chordae, which obviates the need to repeat measurement.
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Fig 1. Preoperative transesophageal echocardiogram. The mitral annulus plane is drawn; then the distance between the head of the posterior papillary muscle and this plane at the coaptation of the leaflets is measured (arrow). This will be the length of our new chorda, based on which the number of tight reverse knots are decided.
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Fig 2. Every millimeter of braided 4-0 Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) contains two tight reverse knots; for instance, 40 tight reverse knots are 20 mm in length.
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Fig 3. The Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) is braided in as many tight knots as is required.
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Fig 4. The 4-0 Gore-Tex (W.L. Gore & Assoc, Flagstaff, AZ) is passed through the tip of the papillary muscle and braided in as many tight knots as is required, and it is passed from the edge of the anterior leaflet at the prolapsing portion and sutured at the atrial side of the leaflet.
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Clinical Experience
Twenty-six consecutive patients with severe mitral regurgitation due to prolapse of the mid-portion of the anterior leaflet (A2) underwent chordal replacement using the technique previously described. The involvement of other mitral valve scallops was excluded from the study to avoid interference between the results. Posterior pericardial annuloplasty was also performed in all the patients. The mean number of the new artificial chordae used for all the patients was 3.4 (median, 3.0; minimum, 3; maximum, 5) per the anterior leaflet. The mean length of the new chordae was 23.8 mm (median, 23.5; minimum, 21; maximum, 27). Except for annuloplasty and chordae replacement, no other techniques were used.
Postoperative transesophageal echocardiography showed good coaptation in all the patients (ie, more than 6 mm) (Fig 5). None of the patients had complications during postoperative hospital care, nor did they show residual mitral regurgitation at discharge. After a mean follow-up of 10 ± 2 months, 23 patients had no mitral regurgitation and 3 of them had mild mitral regurgitation (< 2+).
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Comment
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First introduced in 1985 [7], polytetrafluoroethylene (W. L. Gore & Assoc Inc) is still favored by many surgeons for the replacement of diseased mitral valve chordae because of its long-term durability [3, 8]. All the advantages notwithstanding, polytetrafluoroethylene fails to render a precise determination of the length of chordae any easier.
Artificial chordae can facilitate complex mitral valve repair. Calafiore [6] classifies the different modalities proposed thus far to establish the accurate length of new chordae into functional and anatomical.
The functional techniques for the measurement of new chordae consist of those filling the left ventricle with saline. Kasegawa and colleagues [4] used a small tourniquet to progressively adjust the length of the chordae. David and colleagues, having distended the ventricle with saline, discovered where to coapt the free margin of the leaflets [8]. The same technique was later used by Duebener and colleagues [5], who filled the ventricle with saline and then passed and tied the new chorda after adjusting its length.
The measurement of new chordae is also done by using anatomical techniques in which a nonprolapsing scallop in front of the prolapsing one becomes a reference point as is the case reported by David and colleagues [3]. Custom-made "pre-measured" chordae were made by Von Oppell and Mohr [1], who measured the distance between the correct plane of apposition on an adjacent nonprolapsing segment and the respective papillary muscle. This technique has proved a relative success in minimally invasive mitral valve repair. In patients whose native chordae to the corresponding part of the opposing leaflet are normal, Sarsam [2] suggested that the edges of the anterior and posterior leaflets be approximated with a temporary suture, which is held by the assistant while the surgeon ties the Gore-Tex suture against it. Calafiore [6] ingeniously measured the length of new chordae according to preoperative transesophageal echocardiography. In this technique, the distance between the edge of the prolapsing anterior leaflet and the plane of the mitral annulus is measured (distance A). When the mitral valve is exposed, the elongated chorda, corresponding to the scallop previously evaluated, is measured with a ruler and distance A is subtracted. This is the length of the new chorda.
The previously mentioned techniques have all stood many a surgeon in good stead. However, we are inclined to believe that our technique of chordal replacement according to preoperative transesophageal echocardiography has its own advantages. The fact that our technique uses objective data with a simple preoperative echocardiography eliminates the need to measure the chordae in an exposed mitral valve, which can sometimes prove to be time consuming and not very accurate. Our technique can be used both in conventional and in minimally invasive approaches to mitral valve repair, and although we limited the use of our new technique in this study to the mid-portion of the anterior leaflet, it can be used for the involvement of multiple scallops of the anterior and posterior leaflets. This technique is less precise when isolated A1 or A3 is involved, and its success to a great extent depends upon the accuracy of echocardiographic measurements.
Admittedly, deciding the exact length of new chordae, whether by functional techniques or by anatomical means is a challenge every surgeon must face. Nonetheless, having recourse to a vast repertoire of solutions can be beneficial for a surgeon when choosing the proper technique for every single case in hand.
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References
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- Von Oppell UO, Mohr FW. Chordal replacement for both minimally invasive and conventional mitral valve surgery using premeasured Gore-Tex loops Ann Thorac Surg 2000;70:2166-2168.[Abstract/Free Full Text]
- Sarsam MAL. Simplified technique for determining the length of artificial chordae in mitral valve repair Ann Thorac Surg 2002;73:1659-1660.[Abstract/Free Full Text]
- David TE, Omran A, Armstrong S, Sun Z, Ivanov J. Long-term results of mitral valve repair for myxomatous disease with and without chordal replacement with expanded polytetrafluoroethylene sutures J Thorac Cardiovasc Surg 1998;115:1279-1286.[Abstract/Free Full Text]
- Kasegawa H, Kamata S, Hirasa S, et al. Simple method for determining proper length of artificial chordae in mitral valve repair Ann Thorac Surg 1989;97:98-103.
- Duebener LF, Wendlera O, Nikoloudakisa N, Georgb T, Friesc R, Schäfers HJ. Mitral-valve repair without annuloplasty rings results after repair of anterior leaflet versus posterior leaflet defects using polytetrafluoroethylene sutures for chordal replacement Eur J Cardiothorac Surg 2000;17:206-212.[Abstract/Free Full Text]
- Calefiore AM. Choice of artificial chordae length according to echocardiographic criteria Ann Thorac Surg 2006;81:375-377.[Abstract/Free Full Text]
- Frater RWM. 10th Goretex Chorda Anniversary J Heart Valve Dis 1996;5:348-351.[Medline]
- David TE, Armestrong S, Sun Z. Replacement of chordae tendineae with Gore-Tex sutures: a ten-year experience J Heart Valve Dis 1996;5:352-355.[Medline]
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Abstract
Introduction
