Surgical anatomy of left ventricular outflow tract obstruction in complete atrioventricular septal defect. A concept for operative repair

An integral part of the heart with an atrioventricular septal defect and a Rastelli type A valve configuration is left ventricular outflow tract obstruction. Current surgical techniques do not cater to this particular anatomic facet, and left ventricular outflow tract obstruction has been reported as a postoperative problem. The present study has focused on the surgical anatomy of the mode of attachment of the left superior atrioventricular valve and its relationship to the left ventricular outflow tract. It appeared that the anchoring of the superior leaflet was a major factor in limiting the excursions of the superior leaflet, contributing also to the tightness of the subaortic left ventricular outflow channel. On that basis a surgical repair is proposed in which the greater part of the tightly bound superior leaflet is detached from the septal crest, so that the left ventricular outflow tract is widened.     

Left Ventricular Outflow Tract Obstruction After Mitral Valve Replacement

We describe a patient with left ventricular outflow tract obstruction after mitral valve replacement preserving the anterior subvalvular apparatus. Postoperative transesophageal echocardiography demonstrated systolic narrowing of the left ventricular outflow tract by a bulging septum and systolic anterior motion of the preserved anterior mitral leaflet. Septal myectomy and transaortic mitral apparatus resection enabled us to relieve the left ventricular outflow tract obstruction. This suggests that septal hypertrophy might be a relative contraindication to the preservation of the anterior mitral subvalvular apparatus in mitral replacement.     

Dynamic left ventricular outflow tract obstruction when the anterior leaflet is retained at prosthetic mitral valve replacement

Dynamic left ventricular outflow tract obstruction developed in a patient in whom the anterior leaflet was retained at mitral valve replacement. It was caused by systolic anterior movement of the native anterior leaflet. Reduced outflow tract diameter, resulting from both posterior displacement of the septum and anterior displacement of the native anterior leaflet by porcine stents, was likely instrumental in promoting dynamic obstruction.     

Rescue surgical embolectomy for fatal pulmonary embolism in patient with intracranial hemorrhage

Left ventricular outflow obstruction may result from preserving the anterior leaflet after mitral valve replacement. A 79-year-old woman, who had a mitral valve replacement with the native mitral leaflets left intact 16 years before, was admitted to our hospital with severe dyspnea due to heart failure. Echocardiography showed systolic anterior motion of preserved anterior mitral leaflet, and continuous wave Doppler detected severe left ventricular outflow tract jets during systole without mitral chordal rupture. Surgical incising of the anterior mitral leaflet through the aortic root relieved the obstruction without removing the prosthetic mitral valve.     

Systolic anterior motion of the mitral valve despite the sliding leaflet technique for repair of the mitral valve

We report a systolic anterior motion of the anterior mitral leaflet despite employing the sliding leaflet technique for repair of mitral valve regurgitation. A 65-year-old man with chronic, symptomatic mitral regurgitation due to ruptured chordae tendineae underwent mitral valve repair by quadrangular resection of the posterior leaflet and sliding leaflet technique with ring annuloplasty. After weaning from cardiopulmonary bypass, left ventricular outflow obstruction developed and transesophageal echocardiography demonstrated systolic anterior motion of the mitral valve and severe mitral regurgitation. Non-operative treatment resolved the outflow tract obstruction, systolic anterior motion and mitral regurgitation. We conclude that post-repair systolic anterior motion can still occur after the sliding plasty procedure and that medical treatment can successfully resolve systolic anterior motion and outflow tract obstruction in most patients.     

Potential mechanism of left ventricular outflow tract obstruction after mitral ring annuloplasty

OBJECTIVES: The purpose of this study was to explore whether geometric changes that predispose to left ventricular outflow tract obstruction after mitral ring annuloplasty are coupled to subvalvular apparatus disturbances. METHODS: Radiopaque markers were implanted in sheep: 9 in the ventricle, 1 in the high interventricular septum, 1 on each papillary muscle tip, 8 around the mitral anulus, 4 on the anterior mitral leaflet, and 2 on the posterior leaflet. One group served as control (n = 5); the others were randomized to undergo annuloplasty with the Duran ring (n = 6; Medtronic, Inc, Minneapolis, Minn) or Carpentier-Edwards Physio ring (n = 6; Baxter Healthcare Corp, Irvine, Calif). After a 7- to 10-day recovery period, 3-dimensional marker coordinates were measured with biplane videofluoroscopy. RESULTS: At the beginning of ejection, (1) the anterior leaflet was displaced toward the left ventricular outflow tract; (2) the normal atrially flexed anterior anulus was flattened into the left ventricular outflow tract; (3) the posterior anulus was displaced toward the left ventricular outflow tract; (4) the anterior papillary muscle was displaced septally; and (5) the posterior papillary muscle was dislocated inwardly toward the anterior papillary muscle in the Physio ring group compared with the control group. During ejection, all these structures moved septally, encroaching further on the left ventricular outflow tract. In the Duran ring group, only the posterior anulus was displaced toward the left ventricular outflow tract; the anterior leaflet was not displaced toward the left ventricular outflow tract, and it did not move septally during ejection. CONCLUSIONS: The semirigid Physio ring was associated with perturbations in annular dynamics that caused changes in papillary muscle geometry. We propose an integrated valvular-subvalvular mechanism to explain displacement of the anterior leaflet into the left ventricular outflow tract after mitral ring annuloplasty.     

Nonobstructing Accessory Mitral Valve Tissue and Ventricular Septal Defect

A 4-month-old boy with ventricular septal defect was found to have accessory mitral valve tissue attached to the anterior leaflet of the mitral valve. Operation was successfully performed to excise the accessory mitral tissue in the left ventricular outflow tract and close the ventricular septal defect. Most previously reported cases with accessory mitral valve tissue were associated with left ventricular outflow tract obstruction. This boy had no pressure gradient across the left ventricular outflow tract. The indications for prophylactic excision of nonobstructing accessory mitral valve tissue in a patient with other forms of congenital cardiac disease are discussed.     

A novel technique for the repair of complete atrioventricular septal defects: simplified 2-patch technique

Today complete atrioventricular septal defects can be corrected with acceptable mortality and postoperative morbidity. Although opinions still differ regarding the most appropriate method of choice, some surgeons have proposed a new technique that involves the direct suturing of common atrioventricular valve leaflets to the crest of the ventricular septum. However, we believe that this new approach may be associated with left ventricular outflow tract obstruction and neomitral valve regurgitation. To avoid these potential complications, we decided to modify our repair technique in 2 patients. In this simplified 2-patch technique, the operation was done by direct suturing of postero-inferior common bridging leaflet to the ventricular crest while the space under the antero-superior bridging leaflet was closed with a small triangular shaped Dacron patch. No echocardiographic evidence of neomitral valve regurgitation and left ventricular outflow tract obstruction were detected in either early or late postoperative examinations of these patients.     

Modified sliding leaflet technique for repair of the mitral valve

The sliding leaflet technique reduces the incidence of left ventricular outflow tract obstruction after mitral valve repair. We report a modification of this technique that simplifies the procedure.     

Accessory mitral valve leaflet in an adult with coronary artery disease

Accessory mitral valve leaflet is a very rare cause of left ventricular outflow tract obstruction. We report a patient presenting this cardiac abnormality who undergone cardiac surgery. A 60-year-old man, presented coronary artery disease and moderate left ventricular tract obstruction due to accessory mitral valve leaflet. The accessory mitral valve leaflet had the typical morphology of a parachute-shaped attached partially to the anterior mitral valve leaflet, with chordae tendinae attached to: 1) an accessory papillary muscle inserted at the free-wall closed to the apex; 2) interconnected with the chordae tendinae of the anterior mitral valve leaflet; 3) a second accessory papillary muscle inserted to the interventricular septum. He underwent successful coronary revascularization of 2 vessels and accessory leaflet excision. A review of 21 cases with accessory mitral valve leaflet is reported.     

Complete and Intermediate Atrioventricular Canal in Infants Less than a Year Old: Observations of Anatomical and Pathological Variants in Left Ventricular Outflow Tract

In a study of 13 postmortem specimens from infants with intermediate and complete forms of persisting atrioventricular (AV) canal, potentially obstructive left ventricular outflow tract morphology was apparent in 6. Possible obstructive components included various causes of anterior mitral leaflet immobility, multiple short chordae, anterior malposition of papillary muscles, and septal hypertrophy. Left ventricular outflow tract obstruction can be exaggerated by corrective techniques that do not produce relief of these conditions.     

Preservation of anterior leaflet chordae with modified miki technique: how to do it

During mitral valve replacement, total chordae preservation is very important for left ventricular functions. But leaving anterior leaflet and chordae may cause serious complications, such as left ventricular outflow tract obstruction and impairment in prosthetic valve functions. In this article, we present the anterior leaflet preservation technique by excising the central portion of the anterior leaflet. The rim of the leaflet tissue containing the marginal chordae was divided in two parts without destroying the chordae, and then the rim of leaflet tissue was sutured to the left atrium. This technique provided optimal chordae tension and improved avoidance of complications due to total chordae preservation, in mitral valve replacement operations.     

Mitral valve replacement with bileaflet preservation: a modified technique.

We present a modified bileaflet preserving mitral valve replacement technique to eliminate left ventricular outflow tract obstruction and larger size prosthesis implantation. Mitral anterior leaflet was incised from the middle of leaflet to mitral annulus. Pletgetted sutures were firstly bitten from mitral annulus and then passed from the bottom to the tip of anterior leaflet. These sutures were anchored to prosthesis. Bileaflet prosthesis was put down into the annulus and sutures were ligated on the strut of prosthesis. Posterior leaflet was also preserved. Excessive anterior leaflet tissue was attached to left atrium wall by deeply bitten sutures.     

Mitral annular reconstruction with anterior leaflet flip-over in concomitant surgery for mitral regurgitation associated with extensive posterior annular calcification and hypertrophic obstructive cardiomyopathy

We describe a case of severely calcified posterior mitral annulus associated with grade IV mitral re-gurgitation in addition to significant hypertrophic obstructive cardiomyopathy. A 70-year-old woman underwent successfully annular reconstruction with anterior mitral leaflet flip-over and mitral valve replacement with a bileaflet mechanical prosthesis combined with left ventricular septal myectomy. This technique can serve not only to cover the debrided posterior annulus, but also to eliminate left ventricular outflow tract obstruction and to keep left ventricular function by virtue of not severing ventricular-annular continuity.     

A technique for annular plication to facilitate sliding plasty after extensive mitral valve posterior leaflet resection

The sliding leaflet technique has been used in mitral valve repair in conjunction with posterior leaflet quadrangular resection to avoid left ventricular outflow tract obstruction secondary to systolic anterior motion of the anterior leaflet of the mitral valve. On occasion, despite the use of the sliding leaflet technique, reattachment of the edges of the posterior leaflet after extensive resection can be challenging because of excessive tension. My colleagues and I present our technique to ensure reattachment of the posterior leaflet without tension after extensive resection.     

Transatrial relief of diffuse subaortic stenosis after ventricular septal defect closure

Transatrial enlargement of the left ventricular outflow tract for serious obstruction was performed in 3 patients with previous ventricular septal defect closure. Two patients had recurrent subaortic stenosis as resection had already been performed at initial operation. In all patients, the obstruction was located below the ventricular septal defect patch. Patch enlargement of the left ventricular outflow tract was carried out by opening the ventricular septal defect patch through the tricuspid valve and extending the incision downward through the area of obstruction and the left ventricular body. All patients had uneventful postoperative course and effective relief of left ventricular outflow tract obstruction. We feel that the approach is simple and effective; it avoids a right ventriculotomy and provides a viable option in certain patients with left ventricular outflow tract obstruction.     

Echocardiographic diagnosis of left ventricular outflow tract obstruction after mitral valve replacement with subvalvular preservation.

We describe two cases of left ventricular outflow tract obstruction after mitral valve replacement with complete retention of the subvalvular apparatus. The first patient deteriorated immediately after insertion of a high-profile bioprosthesis. In the second patient, chronic left ventricular outflow tract obstruction developed after the insertion of a low-profile mechanical prosthesis. The clinical course of left ventricular outflow tract obstruction after mitral valve replacement with complete retention of the subvalvular apparatus may differ greatly. Evaluation of the left ventricular outflow tract by perioperative transesophageal echocardiography or epicardial echocardiography is essential in the prevention and treatment of this complication.     

Experience with twenty-eight cases of systolic anterior motion after mitral valve reconstruction by the Carpentier technique.

Systolic anterior motion of the mitral valve with left ventricular outflow tract obstruction after Carpentier-type mitral reconstruction with ring annuloplasty has led some surgeons to abandon an otherwise successful repair or to avoid use of a rigid ring. To assess the long-term significance of such motion, we studied 439 patients undergoing Carpenter mitral reconstruction at our institution between March 1981 and June 1990. The hospital mortality rate was 4.8% (21/439) overall and 3.7% (9/243) for isolated mitral reconstruction. Systolic anterior motion was found in 6.4% (28/438) after the operation, and 2.3% (10/438) had a coexisting left ventricular outflow tract gradient (mean 53 mm Hg). Of the 28 patients with systolic anterior motion, 27 (96.4%) had leaflet prolapse, 17 (60.7%) had undergone more than a 3 cm resection of the posterior leaflet, and two (7.1%) had preexisting idiopathic hypertrophic subaortic stenosis. All patients were treated medically, 14 with negative inotropic agents. Follow-up echocardiograms at a mean of 32 months demonstrated the disappearance of systolic anterior motion in 13 of 28 patients (46.4%) and resolution of the outflow tract gradient in 10 of 10 (100%). At follow-up only one patient was in New York Heart Association class III or IV and required reoperation for rheumatic mitral insufficiency. These data demonstrate that systolic anterior motion after Carpentier mitral reconstruction with ring annuloplasty is not prevalent and should be managed medically in most cases. Associated left ventricular outflow tract obstruction resolves with medical treatment.     

Accessory mitral tissue - an unusual cause of left ventricular outflow tract obstruction

Accessory mitral valve tissue is one of the rare anomalies of embryonic development of the endocardial cushion. We describe here a case of a 9?year old male who presented with dyspnoea on exertion. Transthoracic and transesophageal echocardiography revealed aneurysm of membranous part of the interventricular septum producing left ventricular outflow obstruction. Left ventriculography showed a filling defect in the area of mitral aortic interventricular fibrosa probably a localized subaortic membrane. But intraopertive findings showed an accessory mitral valve tissue attached to the annulus of anterior leaflet with its chordal attachment to the papillary muscles of normal mitral valve and to the interventricular septum. The anomalous tissue was excised with its attachment through the aortotomy and left atriotomy. We emphasize, that fixed type of left ventricular outflow tract obstruction produced by an accessory mitral tissue can mimic an aneurysm of the interventricular septum on echocardiography and surgical excision through bicameral approach is recommended.     

Another pitfall in minimally invasive mitral valve repair

We report a case of severe systolic anterior motion (SAM) and dynamic left ventricular outflow obstruction after repair of a flail posterior leaflet of the mitral valve. The reason for SAM was found to be due to traction on the pericardial stay sutures placed to expose the surgical field. The SAM and the outflow obstruction were completely resolved by cutting these sutures. Our case demonstrates the contribution of geometric factors in the development of SAM and left ventricular outflow obstruction and emphasizes the need to evaluate the heart in its natural position within the mediastinum.