Geometric changes in the aortic valve annulus during the cardiac cycle: impact on aortic valve repair

Effect of TAVR commissural alignment on coronary flow: A fluid-structure interaction analysis

BACKGROUND AND OBJECTIVES

Coronary obstruction is a complication that may affect patients receiving Transcatheter Aortic Valve Replacement (TAVR), with catastrophic consequences and long-term negative effects. To enable healthy coronary perfusion, it is fundamental to appropriately position the device with respect to the coronary ostia. Nonetheless, most TAVR delivery systems do not control commissural alignment to do so. Moreover, no in silico study has directly assessed the effect of commissural alignment on coronary perfusion. This work aims to evaluate the effect of TAVR commissural alignment on coronary perfusion and device performance.

METHODS

A two-way computational fluid-structure interaction model is used to predict coronary perfusion at different commissural alignments. Moreover, in each scenario, hemodynamic biomarkers are evaluated to assess device performance.

RESULTS

Commissural misalignment is shown to reduce the total coronary perfusion by -3.2% and the flow rate to a single coronary branch by -6.8%. It is also observed to impair valvular function by reducing the systolic geometric orifice area by -2.5% and increasing the systolic transvalvular pressure gradients by +5.3% and the diastolic leaflet stresses by +16.0%.

CONCLUSIONS

The present TAVR patient model indicates that coronary perfusion, hemodynamic and structural performance are minimized when the prosthesis commissures are fully misaligned with the native ones. These results support the importance of enabling axial control in new TAVR delivery catheter systems and defining recommended values of commissural alignment in upcoming clinical treatment guidelines.

Use of cardiac magnetic resonance imaging and cardiac magnetic resonance feature-tracking strain analysis to characterize and differentiate aortic annular strain patterns in aortic valve regurgitation versus normal aortic valves

BACKGROUND

Understanding the aortic annulus is important for obtaining reproducible and durable aortic valve (AV) repair and allowing advances for transcatheter AV replacement treatment of aortic regurgitation (AR). Significant limitations exist when using echocardiography and computed tomography-based imaging with feature tracking at the aortic annulus.

AIMS

Cardiac magnetic resonance is used to obtain regional longitudinal strain and can be modified to obtain circumferential annular strain at the fibrous and muscular portions of the AV annulus.

MATERIALS AND METHODS

Holst et al. use a novel method to characterize and prove that adverse annular deformation occurs at the muscular portion of the AV annulus in patients with AR. In their study, cardiovascular magnetic resonance (CMR) imaging and CMR feature-tracking strain analysis are used to characterize aortic annular regional longitudinal strain (RLS) in humans.

RESULTS

The authors convincing show that the direction of muscular annular deformation in patients with AR is opposite to the direction of muscular annular deformation in patients with normal Avs, (median RLS: 4.18% in patients with severe AR vs. -10.41% in well-functioning AVs, p = .024; at RLS muscular annulus).

DISCUSSION AND CONCLUSION

The direction of muscular annular deformation in patients with AR is opposite to the direction of muscular annular deformation in patients with normal AVs. This information will have impactful physiological relevance for surgical and percutaneous treatment of aortic valve pathology.

A novel technique to quantify aortic valve annulus deformation: A pilot study

OBJECTIVES

We evaluated the potential of cardiac magnetic resonance (CMR)-derived strain to assess aortic valve (AV) annulus deformation during the cardiac cycle in regurgitant and well-functioning AVs.

METHODS

Four patients with severe aortic regurgitation and seven healthy controls underwent CMR. Assessment of longitudinal strain was performed by hypothesizing the AV annulus would be the left ventricle in long-axis orientation. Longitudinal strain of the segments belonging to the muscular and fibrous AV annulus was weighted and averaged to obtain regional values (RLS).

RESULTS

Comparison of RLS between regurgitant and well-functioning AVs showed a considerably different deformation of the muscular AV annulus (i.e., median RLS: 4.18 % [patients] vs. -10.41 % [controls], p = .024). The fibrous AV annulus demonstrated comparable deformational changes in both groups.

CONCLUSION

CMR-derived strain allows for quantification of AV annulus deformation during the cardiac cycle and shows an altered RLS in the muscular AV annulus in patients with severe aortic regurgitation.

Focus on the annuloplasty in aortic valve repair: implications from a quantitative multislice computed tomography analysis

Background

Aortic valve (AV) repair has evolved towards a treatment alternative in young patients with AV regurgitation and was accompanied by the development of surgical repair strategies. An efficient and reproducible AV annulus stabilization (i.e., annuloplasty) has been proposed as a crucial component to obtain the long-term stability of AV repair. However, there is still major controversy regarding the most appropriate annuloplasty approach. We aimed to address AV annulus structures which are relevant for AV annuloplasty, based on MS-CT data.

Methods

We retrospectively analysed 326 consecutive patients with AV disease who all underwent preprocedural MS-CT examination. Study cohort was subdivided according to the underlying AV pathology: 25 patients with aortic regurgitation (AR subgroup) (mean age 73±11 years, 68% male), 243 patients with aortic stenosis (AS subgroup) (73±11 years, 68% male) and 58 patients with normally functioning AV (normal AV subgroup) (mean age 76±7 years, 36% male). We systematically measured maximum and minimum AV annulus diameter, AV annular area, projected AV annular perimeter and anatomic AV annular perimeter during mid-systole using MS-CT data. Based on these measurements, AV annular eccentricity index was calculated [(max AV annulus × 100/min AV annulus) - 100]. Furthermore, we assessed the tissue components of AV annular plane, distinguishing between muscular and fibrous portions of the basal ring.

Results

AV annular eccentricity index was significantly larger in the normal AV-subgroup as compared to the AR-subgroup (33.2%±10.7% vs. 27.8%±9.2%; P=0.048) as well as to the AS-subgroup (33.2%±10.7% vs. 20.4%±8.8%; P<0.001). AV annular area was significantly larger in the AR subgroup as compared to the AS subgroup (5.7±1.0 vs. 5.1±0.8 cm²; P=0.003) and normal AV subgroup (5.7±1.0 vs. 4.8±0.8 cm²; P<0.001). Intramuscular plane in the right coronary sinus was significantly increased in the AR subgroup vs. AS subgroup (12.8±2.7 vs. 7.5±3.6 mm; P<0.001) and normal AV subgroup (12.8±2.7 vs. 8.7±3.0 mm; P<0.001). Muscular component of the basal ring was significantly reduced in the AR subgroup vs. AS subgroup (37.5%±5.1% vs. 40.5%±5.5%; P=0.039) and normal AV subgroup (37.5%±5.1% vs. 44.3%±10.2%; P=0.001).

Conclusions

MS-CT enables a quantitative analysis of aortic root anatomy which may have an impact on AV annuloplasty. AR patients differ significantly regarding their AV annular dimensions and basal ring morphology as compared to the AS patients and those with a normal AV function. These findings may have major implications in tricuspid AV repair when designing the most appropriate AV annulus stabilisation technique.