**7. Echo-oriented aortic valve repair**

In aortic valve repair or valve sparing surgery, aortic regurgitation is assessed by TEE. When significant regurgitation remains despite the best possible repair based on the preoperative assessment and acceptable coaptation by inspection, the mechanism of regurgitation under pressure loading needs to be identified in order to make additional repairs on the valve.

The origin and eccentricity of the regurgitant jet is an important key to assessing the problem. The former is assessed in midesophageal short-axis view which can examine which pair of cusps is responsible for incompetency. The latter is assessed in midesophageal aortic valve long-axis view to determine the mechanism of regurgitation. If the regurgitant jet is central and originates from the center of the three cusps, coaptation of the Arantius nodule is incompetent, either by deformity of the nodule or by tethering of the three commissures. When the regurgitant jet is deviated to the anterior mitral leaflet and originates from coaptation between the right coronary cusp and noncoronary cusp (Fig. 12b), prolapse of the right coronary cusp is most likely to be causative and plication of this cusp is indicated (Fig. 12c).

Aortic regurgitation can be caused by aortic dissection by three mechanisms: 1) prolapse of the leaflet due to detachment of the commissures from the aortic wall; 2) tethering of the commissures due to an enlarged sinotubular junction; and 3) invagination of an intimal flap into the aortic valve (Fig. 13 a,b,c). These scenarios can be repaired by reuniting the dissected layers and plicating the sinotubular junction to the size which is nearly equal to the aortic annulus diameter (Fig. 13 d,e). If significant regurgitation remains, the mechanism of regurgitation needs to be explored by TEE and additional interventions performed as necessary.

Fig. 11. A case of everted leaflet of Magna valve. a: severe aortic regurgitation in the noncoronary leaflet, b: immobilized leaflet visualized by lateral bending of the probe tip, c: 3D image of valve prosthesis. On the noncoronary side, the left ventricular outflow tract

In aortic valve repair or valve sparing surgery, aortic regurgitation is assessed by TEE. When significant regurgitation remains despite the best possible repair based on the preoperative assessment and acceptable coaptation by inspection, the mechanism of regurgitation under pressure loading needs to be identified in order to make additional repairs on the valve. The origin and eccentricity of the regurgitant jet is an important key to assessing the problem. The former is assessed in midesophageal short-axis view which can examine which pair of cusps is responsible for incompetency. The latter is assessed in midesophageal aortic valve long-axis view to determine the mechanism of regurgitation. If the regurgitant jet is central and originates from the center of the three cusps, coaptation of the Arantius nodule is incompetent, either by deformity of the nodule or by tethering of the three commissures. When the regurgitant jet is deviated to the anterior mitral leaflet and originates from coaptation between the right coronary cusp and noncoronary cusp (Fig. 12b), prolapse of the right coronary cusp is most likely to be causative and plication of

Aortic regurgitation can be caused by aortic dissection by three mechanisms: 1) prolapse of the leaflet due to detachment of the commissures from the aortic wall; 2) tethering of the commissures due to an enlarged sinotubular junction; and 3) invagination of an intimal flap into the aortic valve (Fig. 13 a,b,c). These scenarios can be repaired by reuniting the dissected layers and plicating the sinotubular junction to the size which is nearly equal to the aortic annulus diameter (Fig. 13 d,e). If significant regurgitation remains, the mechanism of regurgitation needs to be explored by TEE and additional interventions performed as

(LVOT) is seen from the aorta side

this cusp is indicated (Fig. 12c).

necessary.

**7. Echo-oriented aortic valve repair** 

Fig. 12. Echo-oriented aortic valve repair. a: preoperative TEE image of aortic regurgitation (AR) by annuloaortic ectasia, b: residual regurgitation following initial repair with a Valsalva graft, which is directed to the anterior mitral leaflet (AML). c: no regurgitation after plication of right coronary cusp. AAO: ascending aorta, AV: aortic valve, LV: left ventricle

Fig. 13. Three mechanisms of aortic regurgitation in aortic dissection. a: prolapse of a leaflet due to a detached commisure, b: tethering of a leaflet due to an enlarged sinotubular junction (STJ), c: an invaginated flap with tear. d: repair of the sinus of Valsalva sinus based on these mechanisms. e: TEE view after repair. Note that the size of the aortic graft is nearly equal to the aortic valve (AV) annulus. AAO: ascending aorta

Intraoperative Imaging in Aortic Valve Surgery as a Safety Net 17

Fig. 15. Comparison between three groups. Among the three groups (mitral valve repair with or without SAM and septal hypertrophy with SAM), there was no significant

smaller in the SAM positive groups than in the negative groups

vitro studies. *J Am Coll Cardiol* 13, 1438-48.

et al, 2010).

echocardiography.

**9. References** 

difference in ∠AV-MV and AL/PL ratio, but C-Sept, ∠AML-OF, and C-OF was significantly

These results indicate that a dragging effect is the common mechanism in mitral valve disease and septal hypertrophy. SAM occurs when the tip of the anterior mitral leaflet is located in the outflow with a tilted angle to be dragged toward the septum. To prevent SAM in aortic valve replacement, septal myectomy should be adequate so that the anterior mitral leaflet is located out of the new outflow after myectomy. To solve the tilting problem of anterior mitral leaflet, Alfieri's stitch, especially on the A1-P1 side, may be beneficial (Pareda

In conclusion, intraoperative imaging by means of echocardiography provides a variety of data which can help guide the operation including: 1) avoiding unexpected complications; 2) enhancing the efficacy of surgical treatment; and 3) making immediate and appropriate decisions in cases of rare and unpredictable events. To take the best advantage of this capability, it is essential to efficiently and effectively utilize the modalities available with

Cape EG, Simons D, Jimoh A, Weyman AE, Yoganathan AP, & Levine RA. (1989) Chordal

Ender J, Selbach M, Borger MA, Krohmer E, Falk V, Kaisers UX, Mohr FW, & Mukherjee C.

during minimally invasive mitral valve repair. *Ann Thorac Surg* 89, 1866–72.

geometry determines the shape and extent of systolic anterior mitral motion: In

(2010) Echocardiographic identication of iatrogenic injury of the circumex artery

#### **8. Systolic anterior motion of mitral leaflet**

Systolic anterior motion (SAM) of the mitral leaflet occurs not only in cases with mitral valve repair but also in cases with aortic stenosis or hypertrophic cardiomyopathy. SAM may develop following aortic valve replacement and necessitates additional mitral valve replacement. The mechanism of SAM has been reported as being due to a Venturi effect or drag effect (Cape et al, 1989; Sherrid et al, 1993, 2003). There are several risk factors for developing SAM in mitral valve repair, including a short distance between the coaptation point and interventricular septum (C-Sept), a large angle between the mitral and aortic annular plane, an decreased length ratio of the anterior and posterior mitral leaflets, excess valvular tissue, and a hyperkinetic left ventricle (Maslow et al., 1999).

Fig. 14. Measurements for mechanisms of systolic anterior motion. a: conventional parameters, b: assumed outflow in the LV. c: newly introduced two parameters. AML: anterior mitral leaflet, ∠AML-OF: angle between AML and outflow (OF), AV: aortic valve, C-Sept: distance between coaptation and interventricular septum, LA: left atrium, LV: left ventricle, OF-C: distance between OF and coaptation, PML: posterior mitral leaflet

The author believes that there should be a common mechanism of SAM beyond the causative diseases and has analyzed the TEE images obtained in cases of mitral valve repair and septal hypertrophy. In the midesophageal long-axis view, several parameters related to SAM were examined (Fig. 14a): 1) C-Sept; 2) the ratio of lengths of anterior and posterior mitral leaflets (AL/PL ratio); and 3) the angle between the aortic and mitral annular planes (∠AV-MV). Since the LV to LVOT forms a curved but an isometric path (Fig. 14b), the virtual outflow (OF) was assumed as an isometric route along the interventricular septum with a width equal to the dimension of the aortic annulus. The angle and location of the AML tip relative to the OF (∠AML-OF, C-OF) was measured and defined as positive when the AML was away from the outflow and negative when it was within the outflow (Fig. 14c). Measurements were done in 27 cases of mitral valve repair (before and after repair: 54 measuring points including 6 measuring points with SAM and one point of missing data) and 7 cases with septal hypertrophy which underwent mitral valve replacement. The above parameters were compared among three groups: MVP-SAM Group (valve repair without SAM: n=47), MVP+SAM Group (valve repair with SAM: n=6), and SH+SAM Group (septal hypertrophy with SAM: n=7). Among these three groups, there was no significant difference in the ∠AV-MV and AL/PL ratios. However, C-Sept, ∠AML-OF, and C-OF was significantly smaller in the SAM positive groups than in the negative group (Fig. 15).

Systolic anterior motion (SAM) of the mitral leaflet occurs not only in cases with mitral valve repair but also in cases with aortic stenosis or hypertrophic cardiomyopathy. SAM may develop following aortic valve replacement and necessitates additional mitral valve replacement. The mechanism of SAM has been reported as being due to a Venturi effect or drag effect (Cape et al, 1989; Sherrid et al, 1993, 2003). There are several risk factors for developing SAM in mitral valve repair, including a short distance between the coaptation point and interventricular septum (C-Sept), a large angle between the mitral and aortic annular plane, an decreased length ratio of the anterior and posterior mitral leaflets, excess

**8. Systolic anterior motion of mitral leaflet** 

valvular tissue, and a hyperkinetic left ventricle (Maslow et al., 1999).

Fig. 14. Measurements for mechanisms of systolic anterior motion. a: conventional parameters, b: assumed outflow in the LV. c: newly introduced two parameters. AML: anterior mitral leaflet, ∠AML-OF: angle between AML and outflow (OF), AV: aortic valve, C-Sept: distance between coaptation and interventricular septum, LA: left atrium, LV: left ventricle, OF-C: distance between OF and coaptation, PML: posterior mitral leaflet

The author believes that there should be a common mechanism of SAM beyond the causative diseases and has analyzed the TEE images obtained in cases of mitral valve repair and septal hypertrophy. In the midesophageal long-axis view, several parameters related to SAM were examined (Fig. 14a): 1) C-Sept; 2) the ratio of lengths of anterior and posterior mitral leaflets (AL/PL ratio); and 3) the angle between the aortic and mitral annular planes (∠AV-MV). Since the LV to LVOT forms a curved but an isometric path (Fig. 14b), the virtual outflow (OF) was assumed as an isometric route along the interventricular septum with a width equal to the dimension of the aortic annulus. The angle and location of the AML tip relative to the OF (∠AML-OF, C-OF) was measured and defined as positive when the AML was away from the outflow and negative when it was within the outflow (Fig. 14c). Measurements were done in 27 cases of mitral valve repair (before and after repair: 54 measuring points including 6 measuring points with SAM and one point of missing data) and 7 cases with septal hypertrophy which underwent mitral valve replacement. The above parameters were compared among three groups: MVP-SAM Group (valve repair without SAM: n=47), MVP+SAM Group (valve repair with SAM: n=6), and SH+SAM Group (septal hypertrophy with SAM: n=7). Among these three groups, there was no significant difference in the ∠AV-MV and AL/PL ratios. However, C-Sept, ∠AML-OF, and C-OF was

significantly smaller in the SAM positive groups than in the negative group (Fig. 15).

Fig. 15. Comparison between three groups. Among the three groups (mitral valve repair with or without SAM and septal hypertrophy with SAM), there was no significant difference in ∠AV-MV and AL/PL ratio, but C-Sept, ∠AML-OF, and C-OF was significantly smaller in the SAM positive groups than in the negative groups

These results indicate that a dragging effect is the common mechanism in mitral valve disease and septal hypertrophy. SAM occurs when the tip of the anterior mitral leaflet is located in the outflow with a tilted angle to be dragged toward the septum. To prevent SAM in aortic valve replacement, septal myectomy should be adequate so that the anterior mitral leaflet is located out of the new outflow after myectomy. To solve the tilting problem of anterior mitral leaflet, Alfieri's stitch, especially on the A1-P1 side, may be beneficial (Pareda et al, 2010).

In conclusion, intraoperative imaging by means of echocardiography provides a variety of data which can help guide the operation including: 1) avoiding unexpected complications; 2) enhancing the efficacy of surgical treatment; and 3) making immediate and appropriate decisions in cases of rare and unpredictable events. To take the best advantage of this capability, it is essential to efficiently and effectively utilize the modalities available with echocardiography.
