Mitral Annular Dynamics Research Articles

Contribution of mitral annular dynamics to LV diastolic filling with alteration in preload and inotropic state

Mitral annular (MA) excursion during diastole encompasses a volume that is part of total left ventricular (LV) filling volume (LVFV). Altered excursion or area variation of the MA due to changes in preload or inotropic state could affect LV filling. We hypothesized that changes in LV preload and inotropic state would not alter the contribution of MA dynamics to LVFV. Six sheep underwent marker implantation in the LV wall and around the MA. After 7-10 days, biplane fluoroscopy was used to obtain three-dimensional marker dynamics from sedated, closed-chest animals during control conditions, inotropic augmentation with calcium (Ca), preload reduction with nitroprusside (N), and vena caval occlusion (VCO). The contribution of MA dynamics to total LVFV was assessed using volume estimates based on multiple tetrahedra defined by the three-dimensional marker positions. Neither the absolute nor the relative contribution of MA dynamics to LVFV changed with Ca or N, although MA area decreased (Ca, P < 0.01; and N, P < 0.05) and excursion increased (Ca, P < 0.01). During VCO, the absolute contribution of MA dynamics to LVFV decreased (P < 0.001), based on a reduction in both area (P < 0.001) and excursion (P < 0.01), but the relative contribution to LVFV increased from 18 +/- 4 to 45 +/- 13% (P < 0.001). Thus MA dynamics contribute substantially to LV diastolic filling. Although MA excursion and mean area change with moderate preload reduction and inotropic augmentation, the contribution of MA dynamics to total LVFV is constant with sizeable magnitude. With marked preload reduction (VCO), the contribution of MA dynamics to LVFV becomes even more important.

Correlation Between Vortex Ring Formation and Mitral Annulus Dynamics During Ventricular Rapid Filling

One of the most important fluid phenomena observed in the left ventricle during diastole is the presence of vortex rings that develop with a strong jet entering through the mitral valve. The present study is focused on the rapid filling phase of diastole, during which the left ventricle expands and receives blood through the fully open mitral valve. The atrioventricular system during the rapid filling phase was emulated experimentally with a simplified mechanical model in which the relevant pressure decay and the dimension of mitral annulus approximate the physiologic and pathologic values. Digital particle image velocimetry measurements were correlated with the force measurements on the mitral annulus plane to analyze the relation between flow and the mitral annulus motion. The recoil force on the displaced annulus plane was computed on the basis of plane acceleration and plane velocity and correlated with the inflow jet. Measurements of the recoil force for different values of the mitral annulus diameter showed that the recoil force was generated during fluid propulsion and that it is maximal for an annulus diameter close to the normal adult value in a healthy left ventricle. We also tested annulus diameters smaller and larger than the normal one. The smaller annulus corresponds to the stenotic valves and the larger annulus exists in dilated cardiomyopathy cases. In both conditions, the recoil force was found to be smaller than in the normal case. These observations are consistent with the previously reported results for dilated cardiomyopathy and mitral stenosis clinical conditions.

340 Quantification of mitral annular dynamics and papillary muscle positions using real-time 3D echocardiography

340 Quantification of mitral annular dynamics and papillary muscle positions using real-time 3D echocardiography

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Automated Three‐Dimensional Analysis of Mitral Annular Dynamics in Patients with Myocardial Infarction Using Automated Mitral Annular Tracking Method

A newly developed automated mitral annular tracking method (AMAT) has recently become available and enables us to perform automated analysis of mitral annular dynamics. To evaluate mitral annular dynamics using AMAT. AMAT was performed using a Toshiba Aplio SSA-770 ultrasound system in 15 normal healthy volunteers (group N), 16 patients with anterior MI (group A), and 12 inferior MI (group B). The distance between an annular point at end-diastole and at end-systole (distance D) was automatically measured using AMAT at the basal portion of the anterior, lateral, posterior, inferior, and inferoseptal wall. The angle between the mitral annular plane at end-diastole and the direction of movement of each mitral annular point from end-diastole to end-systole (angle A) was also automatically measured at all five mitral annular points. The coefficients of variation (CV) of both distance D and of angle A were calculated as indices of asynchrony of mitral annular dynamics. CV of distance D in group A (22 +/- 9% (P < 0.01 vs group N)) and group B (22 +/- 10% (P < 0.01 vs group N)) were both significantly larger than in group N (13 +/- 4%). CV of angle A in group A (15 +/- 10% (P < 0.05 vs group N)) and group B (15 +/- 10% (P < 0.05 vs group N)) were also significantly larger than that in group N (8 +/- 3%). Automated analysis using AMAT showed that mitral annular dynamics of patients with MI were less symmetrical than in normal healthy volunteers.

Misinterpretation About the Contribution of the Left Ventricular Long-Axis Shortening to the Stroke Volume

Misinterpretation about the contribution of the left ventricular long-axis shortening to the stroke volume

Regional contribution of mitral annular dynamics to LV filling

Mitral annular (MA) excursion is an established variable, related to both systolic and diastolic left ventricular (LV) function. MA excursion during diastole encompasses a volume that is part of the total LV filling, and altered excursion or area change of the MA may impair filling. We tested the hypothesis that LV inotropic state and loading condition alter regional LV filling properties. Six sheep underwent marker implantation in the LV wall and around the MA. After 7–10 days, biplane fluoroscopy was used to obtain 3-D marker dynamics during: 1) control conditions (CC), 2) after administration of calcium (C), 3) control conditions (NC), and 4) after administration of nitroprusside (N). Multiple tetrahedral volumes were calculated to measure the contribution of MA excursion and area change to LV filling. Compared with respectively control (mean±SD, *=p<0.05, **=p<0.01): 1) The contribution of MA dynamics to LV filling did not change with C (C: 3.2±0.9 vs. CC: 3.1±0.9 ml), but MA excursion increased (0.5±0.1** vs. 0.4±0.1 cm) and area decreased (6.4±0.7** vs. 7.4±0.7 cm2); 2) Total LV filling decreased with N (N: 15.4±4.6* vs. NC: 17.9±5.5 ml) without change in the absolute or relative contribution of MA dynamics to LV filling (3.0±0.7 vs. 3.7±1.1 ml) and (20.5±3.6 vs. 19.1±3.4 %) respectively, although MA mean area decreased (6.5±0.6** vs. 7.3±0.8 cm2). Although the mechanisms behind the contribution of MA dynamics to total LV filling change with inotropic state and loading condition, this component is robust and has substantial magnitude, accounting for approximately one-fifth of total LV filling.

Insight Into Normal Mitral and Tricuspid Annular Dynamics in Pediatrics: A Real-time Three-dimensional Echocardiographic Study

Although there are animal or adult studies analyzing annular motion of the mitral valve (MV) or tricuspid valve (TV) separately, there are no data analyzing interaction between the MV and TV, or data from the pediatric population. A total of 17 healthy children (age 3-15 years) were enrolled in this study. Using real-time 3-dimensional echocardiography, annular area, perimeter, segmental diameter, and bending angle were obtained and analyzed. MV area increased during systole, in contrast to TV area, which decreased. TV area demonstrated a greater reduction of lateral diameter during systole. Bending motion became most acute in early diastole, which was greater for the TV. MV area change differs from adults, which may be explained by a more compliant myocardium in children. Greater lateral forces on TV prevent it from becoming circular, thus, preserving valve competency. Both valves show a bending motion, which becomes most prominent during isovolumic relaxation continuing into early diastole for the TV, suggesting a relationship with torsional forces within the ventricles.

Effect of catheter device closure of atrial septal defect on diastolic mitral annular motion

Atrial septal defect closure with the Amplatzer septal occluder has a negative effect on diastolic mitral annulus motion in terms of decreasing longitudinal septal annular motion and changing the relation between the annulus motion and mitral inflow.

Atrial contraction and mitral annular dynamics during acute left atrial and ventricular ischemia in sheep.

In six sheep, radiopaque markers were placed on the left ventricle (LV), the mitral annulus, the left atrium (LA), and the central edge of both mitral leaflets to investigate the effects of acute LV ischemia on atrial contraction, mitral annular area (MAA), and mitral regurgitation (MR). Animals were studied with biplane videofluoroscopy and transesophageal echocardiography before and during balloon occlusion of the left anterior descending (LAD), distal circumflex (dLCX), and proximal circumflex (pLCX) coronary arteries. MAA and LA area were calculated from the corresponding markers. LAD occlusion did not alter LA area reduction or presystolic MAA reduction, whereas dLCX occlusion resulted in a mild decrease in the former with no change in the latter. Neither occlusion resulted in MR. pLCX occlusion, however, significantly decreased LA area and presystolic MAA reduction and resulted in increased end-diastolic MAA, delayed valve closure from end diastole, and MR. Decreased atrial contractile function, as observed during acute posterolateral ischemia, is linked to diminished presystolic mitral annular reduction, a larger mitral annular size at end diastole, and MR.

Hemodynamic performance of an unstented xenograft mitral valve substitute

Objective: Stentless mitral xenografts offer potential clinical benefits because they mimic the normal bileaflet mitral valve. How best to implant them and their hemodynamic performance and durability, however, remain unknown. Methods: A stentless porcine mitral xenograft valve (Medtronic physiologic mitral valve) was implanted in 7 sheep with papillary muscle sewing tubes attached with transmural left ventricular sutures. Radiopaque markers were inserted on the leaflets, annular cuff, papillary tips, and left ventricle. After 10 ± 5 days, the animals were studied with biplane videofluoroscopy to determine 3-dimensional marker coordinates at baseline and during dobutamine infusion. Transesophageal echocardiography assessed mitral regurgitation and valvular gradients. Mitral annular area was calculated from the annular markers. Physiologic mitral valve leaflet and annular dynamics were compared with 8 native sheep valves. Results: Average mitral regurgitation grade at baseline was 1.2 ± 1.0 (range, 0-4), and the mean transvalvular pressure gradients were 3.6 ± 1.3 and 6.2 ± 2.2 mm Hg during baseline and dobutamine infusion, respectively. Xenograft mitral annular area contraction throughout the cardiac cycle was reduced (6% ± 6% vs 13% ± 4% for physiologic mitral valve and control valve, respectively; P =.03). Physiologic mitral valve leaflet geometry during closure differed from the native valve, with the anterior leaflet being convex to the atrium and with little motion of the posterior leaflet. Three animals survived more than 3 months; good healing of the annular cuff and papillary muscle tubes was demonstrated. Conclusion: This stentless xenograft mitral valve substitute had low gradients at baseline and during stress conditions early postoperatively, with mild mitral regurgitation. Preliminary analysis of healing characteristics appeared favorable at 3 months. Additional studies are needed to determine long-term xenograft mitral valve performance and resistance to calcification.J Thorac Cardiovasc Surg 2002;124:541-52

Three-dimensional geometric comparison of partial and complete flexible mitral annuloplasty rings

Background: It has previously been shown in sheep that mitral annular physiologic dynamics during the cardiac cycle are abolished by complete ring annuloplasty, but recent clinical studies suggest that flexible partial ring annuloplasty preserves normal mitral annular dynamics. Methods: Eight radiopaque markers were sutured equidistantly around the mitral anulus in 3 groups of sheep: no-ring control animals (n = 16); animals with a flexible Tailor partial ring annuloplasty (n = 6; St Jude Medical, Inc, St Paul, Minn); and animals with a flexible Duran ring annuloplasty (n = 7; Medtronic, Inc, Minneapolis, Minn). After 7 to 10 days&' recovery, 3-dimensional marker coordinates were measured by biplane cinefluoroscopy. Mitral annular area and folding (defined as displacement of the mitral anulus from a least-squares plane) and mitral annular septal-lateral and commissure-commissure dimensions were calculated from the 3-dimensional marker coordinates throughout the cardiac cycle every 17 ms. Results: In the no-ring control group mitral annular area varied from 8.0 ± 0.2 to 7.2 ± 0.2 cm2 (10% ± 2%), and the septal-lateral and commissure-commissure dimensions varied from 27.7 ± 0.4 to 25.9 ± 0.4 mm (7% ± 1%) and from 38.2 ± 0.8 to 36.4 ± 0.8 mm (5% ± 1%), respectively (mean ± standard error of the mean, P <.001 for all comparisons). In the Duran ring annuloplasty and Tailor partial ring annuloplasty groups, the anulus was fixed in size throughout the cardiac cycle (area = 4.8 ± 0.1 and 5.3 ± 0.3 cm2, septal-lateral = 21.8 ± 0.7 and 22.0 ± 0.8 mm, and commissure-commissure = 27.7 ± 0.7 and 31.2 ± 1.7 mm). Mitral annular folding did not differ significantly between the control and Tailor partial ring annuloplasty groups but was dampened in the Duran ring annuloplasty group. Conclusions: Partial Tailor flexible ring annuloplasty fixed mitral annular area and dimensions throughout the cardiac cycle in sheep; however, it preserved physiologic mitral annular folding dynamics, which might be important in terms of long-term valve function and prevention of left ventricular outflow tract obstruction.

Mitral annular dynamics during rapid atrial pacing

Introduction: Ovine mitral annular area (MAA) reduction predominantly occurs before ventricular systole. We used the myocardial marker methods to investigate left atrial and MAA dynamics during rapid atrial pacing. Methods: Seven sheep underwent implantation of 21 myocardial markers around the mitral annulus, the left ventricle and left atrium. After 7 to 10 days, animals were studied with biplane videofluoroscopy to determine 3-dimensional marker coordinates unpaced and during rapid atrial pacing at 140 minutes–1. Left ventricle volume, left atrial volume (LAV), and MAA were calculated from marker coordinates. End diastole (ED) was defined at peak of the electrocardiogram R wave; times of minimum MAA and minimum LAV were expressed relative to ED (t = 0). Percent reduction in MAA and LAV were calculated from maximum and minimum values between diastole and early systole. Results: The time of minimum MAA occurred earlier relative to ED during rapid pacing compared with control (–48 ± 21 vs 19 ± 14 msec; P <.001), as did the time of minimum LAV (–47 ± 18 vs 4 ± 16 msec; P <.001). Minimum MAA and LAV were significantly smaller with rapid pacing (6.8 ± 0.6 vs 6.5 ± 0.5 cm2; P <.05, respectively; and 15.4 ± 2.4 vs 16.5 ± 2.3 mL; P <.01, respectively), and a relatively greater fractional reduction in MAA and LAV was observed during presystole. Conclusions: Rapid atrial pacing resulted in greater MAA and LAV reduction, both of which occurred entirely during diastole. This study supports the notion that MAA reduction is closely linked to LA dynamics. (Surgery 2000;128:361-7.)

Mitral annular size and shape in sheep with annuloplasty rings

Background: Mitral annuloplasty is an important element of most mitral repairs, yet the effects of various types of annuloplasty rings on mitral annular dynamics are still debated. Recent studies suggest that flexible rings preserve physiologic mitral annular area change during the cardiac cycle, while rigid rings do not. Methods: To clarify the effects of mitral ring annuloplasty on mitral annular dynamic geometry, we sutured 8 radiopaque markers equidistantly around the mitral anulus in 3 groups of sheep (n = 7 each: no ring, Carpentier-Edwards semi-rigid Physio-Ring [Baxter Healthcare Corp, Edwards Division, Santa Ana, Calif], and Duran flexible ring [Medtronic, Inc, Minneapolis, Minn]). Ring sizes were selected according to anterior leaflet area and inter-trigonal distance (Physio-Ring 28 mm, n = 7; Duran ring 31 mm, n = 5, and 29 mm, n = 2). After 8 ± 1 days of recovery, the sheep were sedated and studied by means of biplane videofluoroscopy. Mitral annular area was calculated from 3-dimensional marker coordinates without assuming circular or planar geometry. Results: In the no ring group, mitral annular area varied during the cardiac cycle by 11% ± 2% (mean ± SEM; maximum = 7.6 ± 0.2, minimum = 6.8 ± 0.2 cm 2; P ≤ .001). Mitral annular area was fixed in the Physio-Ring group (4.6 ± 0.1 cm 2) and, surprisingly, also static in the Duran ring group (4.8 ± 0.1 cm 2; P = .26 vs Physio-Ring). Furthermore, mitral annular 3-dimensional shape changed in the no-ring group during the cardiac cycle, but not in the Physio-Ring or Duran groups. Conclusions: Mitral annular area and shape did not change during the cardiac cycle after ring annuloplasty, regardless of ring type. Thus mitral annular area reduction, independent of intrinsic ring flexibility, is the chief mechanism responsible for the salutary effects of mitral ring annuloplasty. (J Thorac Cardiovasc Surg 1999;117:302-9)

Assessment of mitral annular dynamics during diastole by Doppler tissue imaging: Comparison with mitral Doppler inflow in subjects without heart disease and in patients with left ventricular hypertrophy

The purpose of this study was to determine the normal pattern and magnitude of mitral annular velocities in diastole by Doppler tissue imaging (DTI) and to assess whether this is altered in patients with left ventricular hypertrophy. Mitral annulus velocities were measured by DTI. Peak and time-velocity integral were measured from the DTI tracings and the timing of the velocities in relation to electrocardiogram. DTI was compared with M-mode echo of the annulus and mitral inflow Doppler velocities. Integrated annular velocities by DTI correlated with the annular displacement. Early diastolic velocities decreased with age and in patients with left ventricular hypertrophy. In the hypertrophy group, early diastolic velocities were significantly lower than normal even after correcting for age. Patients with left ventricular hypertrophy also showed a delay in peak early diastolic mitral annular velocity (5.5 ± 21 msec after the E wave). In conclusion, mitral annular velocity in diastole is readily recorded by DTI. The magnitude and the pattern of these velocities are significantly altered by age and by left ventricular hypertrophy. This method provides a new insight into diastolic filling events and may prove useful in detecting abnormal diastolic function.