Paradoxic decrease in ischemic mitral regurgitation with papillary muscle dysfunction: insights from three-dimensional and contrast echocardiography with strain rate measurement

Myocardial Contractile Mechanics in Ischemic Mitral Regurgitation: Multicenter Data Using Stress Perfusion Cardiovascular Magnetic Resonance

BACKGROUND

Left ventricular (LV) ischemia has been variably associated with functional mitral regurgitation (FMR). Determinants of FMR in patients with ischemia are poorly understood.

OBJECTIVES

This study sought to test whether contractile mechanics in ischemic myocardium underlying the mitral valve have an impact on likelihood of FMR.

METHODS

Vasodilator stress perfusion cardiac magnetic resonance was performed in patients with coronary artery disease (CAD) at multiple centers. FMR severity was confirmed quantitatively via core lab analysis. To test relationship of contractile mechanics with ischemic FMR, regional wall motion and strain were assessed in patients with inducible ischemia and minimal (≤5% LV myocardium, nontransmural) infarction.

RESULTS

A total of 2,647 patients with CAD were studied; 34% had FMR (7% moderate or greater). FMR severity increased with presence (P < 0.001) and extent (P = 0.01) of subpapillary ischemia: patients with moderate or greater FMR had more subpapillary ischemia (odds ratio [OR]: 1.13 per 10% LV; 95% CI: 1.05-1.21; P = 0.001) independent of ischemia in remote regions (P = NS); moderate or greater FMR prevalence increased stepwise with extent of ischemia and infarction in subpapillary myocardium (P < 0.001); stronger associations between FMR and infarction paralleled greater wall motion scores in infarct-affected territories. Among patients with inducible ischemia and minimal infarction (n = 532), wall motion and radial strain analysis showed impaired subpapillary contractile mechanics to associate with moderate or greater FMR (P < 0.05) independent of remote regions (P = NS). Conversely, subpapillary ischemia without contractile dysfunction did not augment FMR likelihood. Mitral and interpapillary dimensions increased with subpapillary radial strain impairment; each remodeling parameter associated with impaired subpapillary strain (P < 0.05) independent of remote strain (P = NS). Subpapillary radial strain (OR: 1.13 per 5% [95% CI: 1.02-1.25]; P = 0.02) and mitral tenting area (OR: 1.05 per 10 mm2 [95% CI: 1.00-1.10]; P = 0.04) were associated with moderate or greater FMR controlling for global remodeling represented by LV end-systolic volume (P = NS): when substituting sphericity for LV volume, moderate or greater FMR remained independently associated with subpapillary radial strain impairment (OR: 1.22 per 5% [95% CI: 1.02-1.47]; P = 0.03).

CONCLUSIONS

Among patients with CAD and ischemia, FMR severity and adverse mitral apparatus remodeling increase in proportion to contractile dysfunction underlying the mitral valve.

Ischemia-Mediated Dysfunction in Subpapillary Myocardium as a Marker of Functional Mitral Regurgitation

OBJECTIVES

The goal of this study was to test whether ischemia-mediated contractile dysfunction underlying the mitral valve affects functional mitral regurgitation (FMR) and the prognostic impact of FMR.

BACKGROUND

FMR results from left ventricular (LV) remodeling, which can stem from myocardial tissue alterations. Stress cardiac magnetic resonance can assess ischemia and infarction in the left ventricle and papillary muscles; relative impact on FMR is uncertain.

METHODS

Vasodilator stress cardiac magnetic resonance was performed in patients with known or suspected coronary artery disease at 7 sites. Images were centrally analyzed for MR etiology/severity, mitral apparatus remodeling, and papillary ischemia.

RESULTS

A total of 8,631 patients (mean age 60.0 ± 14.1 years; 55% male) were studied. FMR was present in 27%, among whom 16% (n = 372) had advanced (moderate or severe) FMR. Patients with ischemia localized to subpapillary regions were more likely to have advanced FMR (p = 0.003); those with ischemia localized to other areas were not (p = 0.17). Ischemic/dysfunctional subpapillary myocardium (odds ratio: 1.24/10% subpapillary myocardium; confidence interval: 1.17 to 1.31; p < 0.001) was associated with advanced FMR controlling for infarction. Among a subgroup with (n = 372) and without (n = 744) advanced FMR matched (1:2) on infarct size/distribution, patients with advanced FMR had increased adverse mitral apparatus remodeling, paralleled by greater ischemic/dysfunctional subpapillary myocardium (p < 0.001). Although posteromedial papillary ischemia was more common with advanced FMR (p = 0.006), subpapillary ischemia with dysfunction remained associated (p < 0.001), adjusting for posteromedial papillary ischemia (p = 0.074). During follow-up (median 5.1 years), 1,473 deaths occurred in the overall cohort; advanced FMR conferred increased mortality risk (hazard ratio: 1.52; 95% confidence interval: 1.25 to 1.86; p < 0.001) controlling for left ventricular ejection fraction, infarction, and ischemia.

CONCLUSIONS

Ischemic and dysfunctional subpapillary myocardium provides a substrate for FMR, which predicts mortality independent of key mechanistic substrates.

Importance of Myocardial Fibrosis in Functional Mitral Regurgitation: From Outcomes to Decision-Making

Functional mitral regurgitation (FMR) is a common and complex valve disease, in which severity and risk stratification is still a conundrum. Although risk increases with FMR severity, it is modulated by subjacent left ventricular (LV) disease. The extent of LV remodeling and dysfunction is traditionally evaluated by echocardiography, but a growing body of evidence shows that myocardial fibrosis (MF) assessment by cardiac magnetic resonance (CMR) may complement risk stratification and inform treatment decisions. This review summarizes the current knowledge on the comprehensive evaluation that CMR can provide for patients with FMR, in particular for the assessment of MF and its potential impact in clinical decision-making.

A new disease entity: Atrial functional mitral regurgitation

Functional mitral regurgitation (MR) has been traditionally known as secondary MR resulting from left ventricular (LV) dilatation and systolic dysfunction. However, deterioration of functional MR also relates to mitral annular (MA) dilatation. Furthermore, MA dilatation due to left atrial dilatation in patients with atrial fibrillation (AF) can also cause functional MR, even in the absence of LV systolic dysfunction, in a condition referred to as "atrial functional MR" (AFMR). AFMR also has other etiological factors, including disruption of the MA saddle shape, reduction in MA contractility, inadequate compensation for the MA dilatation resulting from the lack of leaflet remodeling, and hamstringing of the posterior mitral leaflet by atriogenic tethering. AFMR has recently received much attention as an important cause of heart failure, and it represents a considerable therapeutic target in heart failure patients with AF. The traditional functional MR occurring in patients with LV dilatation and systolic dysfunction has since been designated "ventricular functional MR" (VFMR) to distinguish it from AFMR. This review article compares the current perceptions of newly recognized AFMR with those of traditional VFMR.

Impact of posteromedial papillary muscle infarction on mitral regurgitation during ST-segment elevation myocardial infarction

The exact role of papillary muscle infarction (PMI) during the acute phase of acute ST-segment elevation myocardial infarction (STEMI) is not well understood, as existing data on the impact of PMI location is conflicting. We hypothesized that infarction of the posteromedial papillary muscle (PM-PMI) as determined by cardiac magnetic resonance imaging might be associated with an increased incidence of mitral valve regurgitation in the first week after STEMI. 242 patients with first STEMI underwent a late-enhancement (LGE-) cardiac magnetic resonance imaging within a median of 2 (IQR 2-5) days and echocardiography within 3 (IQR 2-5) days after primary angioplasty for the index event. PMI was scored based on short axis slices (AL-PMI: anterolateral PMI, PM-PMI, AL/PM-PMI: AL- and PM-PMI). Patients with PM-PMI had significantly higher odds (OR 2.62, p < 0.01) for the occurrence of mitral regurgitation than patients with no-PMI, AL-PMI or AL/PM-PMI. Furthermore, advanced age, non-anterior infarct location and longer pain-to-balloon time were identified as risk factors for the occurrence of mitral regurgitation. Binary logistic regression analysis revealed that PM-PMI is a predictor of mitral regurgitation independent of infarct location and age (OR 2.229, CI 1.078-4.903, p = 0.031). PM-PMI as determined by cardiac magnetic resonance imaging is an independent predictor of mitral regurgitation in the setting of acute STEMI. Our data might improve our understanding of the dynamic nature of functional mitral regurgitation.

Impact of Mitral Regurgitation Severity and Cause on Effort Tolerance-Integrated Stress Myocardial Perfusion Imaging and Echocardiographic Assessment of Patients With Known or Suspected Coronary Artery Disease Undergoing Exercise Treadmill Testing

Background Mitral regurgitation ( MR ) has the potential to impede exercise capacity; it is uncertain whether this is because of regurgitation itself or the underlying cause of valvular insufficiency. Methods and Results The population comprised 3267 patients who underwent exercise treadmill myocardial perfusion imaging and transthoracic echocardiography within 6±8 days. MR was present in 28%, including 176 patients (5%) with moderate or greater MR . Left ventricular systolic function significantly decreased and chamber size increased in relation to MR , paralleling increments in stress and rest myocardial perfusion deficits (all P<0.001). Exercise tolerance (metabolic equivalents of task) decreased stepwise in relation to graded MR severity ( P<0.05). Workload was significantly lower with mild versus no MR (mean±SD, 9.8±3.0 versus 10.1±3.0; P=0.02); magnitude of workload reduction significantly increased among patients with advanced versus those with mild MR (mean±SD, 8.6±3.0 versus 9.8±3.0; P<0.001). MR -associated exercise impairment was accompanied by lower heart rate and blood pressure augmentation and greater dyspnea (all P<0.05). Both functional and nonfunctional MR subgroups demonstrated significantly decreased effort tolerance in relation to MR severity ( P≤0.01); impairment was greater with functional MR ( P=0.04) corresponding to more advanced left ventricular dysfunction and dilation (both P<0.001). Functional MR predicted reduced metabolic equivalent of task-based effort (B=-0.39 [95% CI, -0.62 to -0.17]; P=0.001) independent of MR severity. Among the overall cohort, advanced (moderate or greater) MR was associated with reduced effort tolerance (B=-1.36 [95% CI, -1.80 to -0.93]; P<0.001) and remained significant ( P=0.01) after controlling for age, clinical indexes, stress perfusion defects, and left ventricular dysfunction. Conclusions MR impairs exercise tolerance independent of left ventricular ischemia, dysfunction, and clinical indexes. Magnitude of exercise impairment parallels severity of MR .

Characterization of 3-dimensional papillary muscle displacement in in vivo ovine models of ischemic/functional mitral regurgitation

OBJECTIVE

Papillary muscle (PM) displacement contributes to ischemic/functional mitral regurgitation (IMR/FMR). The displaced PMs pull the mitral leaflets into the left ventricle (ie, toward the apex) thus hampering leaflet coaptation. Intuitively apical leaflet tethering results from apical PM displacement. The 3-dimensional directions of PM displacement are, however, incompletely characterized.

METHODS

Data from in vivo ovine models of IMR (6-8 weeks of posterolateral infarction, n = 12) and FMR (9-21 days of rapid left ventricular pacing, n = 11) were analyzed. All sheep had radiopaque markers implanted on the anterior and posterior PM (PPM) tips, around the mitral annulus, and on the left ventricular apex. To explore 3-dimensional PM displacement directions, differences in marker coordinates were calculated at end-systole before and during IMR/FMR using a right-handed coordinate system centered on the mitral annular "saddle horn" with the y-axis passing through the apical marker.

RESULTS

No apical PM displacement was observed during either IMR or FMR. The anterior PM displaced laterally during FMR. Posterolateral PPM displacement was observed during IMR and FMR.

CONCLUSIONS

Experimental in vivo ovine models suggest posterolateral PPM displacement as a predominant pathomechanism leading to apical leaflet tethering during IMR/FMR.

Dynamic cardiac anatomy: the "cypress tree" papillary muscle root

Introduction: The understanding of gross cardiac anatomy has been relatively stable over the last 80 years, reliant on well-established autopsy findings. The advent of dynamic imaging by cardiac MRI and CT provides a window to view anatomic features in vivo, providing insights typically masked at autopsy due to death.

Hypothesis: We hypothesize that cardiac magnetic resonance (CMR) with its high spatial and temporal resolution allows detection of anatomic features not previously appreciated at autopsy.

Methods: Two hundred fifty-five sequential, CMR examinations were retrospectively examined to describe the anatomic features of the LV (left ventricular) PM (papillary muscles). Specifically, the origin of the base of the PM was delineated. The insertion of the PM was seen in 255/255 patients.

Results: In 249 out of 255 patients (97.6%), the appearance of the PM was not a uniform muscle arising from the inner face of the LV myocardium, but was a finger-like series of long, slender trabeculae carneae traversing >1 cm before inserting into the main body of PM challenging our previous understanding of PM anatomy.

Conclusion: The capabilities of dynamic CMR to view cardiac features in vivo non-invasively provides a useful tool to study cardiac anatomy. Unlike the widely accepted representation of papillary muscles, uniformly arising from the floor of the LV, the base resolves into a ‘cypress-tree’ root-like structure with multiple thin projections before coalescing into a thick muscle head. Such observations have far reaching clinical implications in areas such as mitral regurgitation, post-MI remodeling and electrical transmission of the His-Purkinje system, and further work is indicated to delineate the role of non-invasive imaging in these areas.

Papillary muscles of left ventricle-Morphological variations and it's clinical relevance

Introduction

The two left ventricular papillary muscles are small structures at sternocostal and inferior wall but are vital to mitral valve competence. Extra papillary muscles could be found. Partial or complete rupture, complicating acute myocardial infarction, causes severe or even catastrophic mitral regurgitation, potentially correctable by surgery. Detailed knowledge of normal anatomy and variations is vital for accurate interpretation of information by echocardiography and for surgical repair.

Materials and methods

The material for present study consisted of 52 formalin fixed adult apparently normal cadaveric hearts belonging to either sex obtained from the Department of Anatomy. These hearts were dissected carefully to open the left ventricle and to expose the papillary muscles. According to their attitudinal position they were described as supero-lateral (S-L) and inferoseptal muscle (I-S) instead of conventional anterolateral and posteromedial. Different morphological features of papillary muscles were noted and measurements were taken.

Results

Classical picture of left ventricular papillary muscle was found only in 25% cases. Additionally extra muscles were found 34.61% and 71.15% in S-L and I-S group, respectively. Different shapes and pattern of papillary muscles were also been identified. An additional attribute of this study was measurement of length and breadth of papillary muscles which thus provides a base line data for further detailed studies in a large scale.

Conclusion

Oriental nomenclature is necessary not only for anatomist but also for electrocardiographers. Breadth of papillay muscle should be taken into morphometric account as for screening of hypertrophic cardiomyopathy. Proper anatomical knowledge is crucial for clinicians, surgeons and radiologists.

Functional Mitral Regurgitation: Imaging Insights, Clinical Outcomes and Surgical Principles

Functional mitral regurgitation (MR; FMR) is the most common type of MR and its development is associated with increased morbidity and mortality. Leaflet tethering with apical shift of the papillary muscle due to adverse left ventricular remodeling and loss of normal leaflet coaptation is the principal mechanism of FMR. Echocardiography plays a central role in the assessment of the FMR. The development of 3D echocardiography has allowed for assessment of the geometric changes of mitral valve morphology and spatial relationship with the left ventricle that accompanies FMR. 2D/3D echocardiographic findings, clinical outcomes of FMR are reviewed and role of surgical intervention is discussed.

Papillary Muscle Free Strain in Patients with Severe Degenerative and Functional Mitral Regurgitation

FUNDAMENTO:

The role of papillary muscle function in severe mitral regurgitation with preserved and reduced left ventricular ejection fraction and the method of choice to evaluate PM have still been the subjects of controversy.

OBJECTIVES:

To evaluate and compare papillary muscle function in and between patients with severe degenerative and functional mitral regurgitation by using the free strain method.

METHODS:

64 patients with severe mitral regurgitation - 39 patients with degenerative mitral regurgitation (DMR group) and 25 patients with severe functional mitral regurgitation (FMR group) - and 30 control subjects (control group) were included in the study. Papillary muscle function was evaluated through the free strain method from apical four chamber images of the anterolateral papillary muscle (APM) and from apical three chamber images of the posteromedial papillary muscle (PPM). Global left ventricular longitudinal and circumferential strains were evaluated by applying 2D speckle tracking imaging.

RESULTS:

Global left ventricular longitudinal strain (DMR group, -17 [-14.2/-20]; FMR group, -9 [-7/-10.7]; control group, -20 [-18/-21] p < 0.001), global left ventricular circumferential strain (DMR group, -20 [-14.5/-22.7]; FMR group, -10 [-7/-12]; control group, -23 [-21/-27.5] p < 0.001) and papillary musle strains (PPMS; DMR group, -30.5 [-24/-46.7]; FMR group, -18 [-12/-30]; control group; -43 [-34.5/-39.5] p < 0.001; APMS; DMR group, (-35 [-23.5/-43]; FMR group, -20 [-13.5/-26]; control group, -40 [-32.5/-48] p < 0.001) were significantly different among all groups. APMS and PPMS were highly correlated with LVEF (p < 0.001, p < 0.001; respectively), GLS (p < 0.001, p < 0.001; respectively) and GCS (p < 0.001, p < 0.00; respectively) of LV among all groups. No correlation was found between papillary muscle strains and effective orifice area (EOA) in both groups of severe mitral regurgitation.

CONCLUSIONS:

Measuring papillary muscle longitudinal strain by the free strain method is practical and applicable. Papillary muscle dysfunction plays a small role in severe MR due to degenerative or functional causes and papillary muscle functions in general seems to follow left ventricular function. PPM is the most affected PM in severe mitral regurgitation in both groups of DMR and FMR.

FUNDAMENTO:

O papel da função do músculo papilar na regurgitação mitral grave com fração de ejeção do ventrículo esquerdo preservada e reduzida e o método de escolha para avaliar PM ainda são objetos de controvérsia.

OBJETIVOS:

Avaliar e comparar a função dos músculos papilares entre pacientes com insuficiência mitral funcional e degenerativa pelo método free strain.

MÉTODOS:

64 pacientes com insuficiência mitral grave - 39 pacientes com insuficiência mitral degenerativa grave (grupo IMD) e 25 com insuficiência mitral funcional grave (grupo IMF) - e 30 indivíduos controle (grupo controle) foram incluídos no estudo. A função dos músculos papilares foi avaliada pelo método free strain a partir de imagens apicais quatro-câmaras do músculo papilar anterolateral (MPA) e imagens apicais três-câmaras do músculo papilar posteromedial (MPP). Strains circunferenciais e longitudinais globais do ventrículo esquerdo foram avaliados por meio de imagens bidimensionais a partir do rastreamento de conjunto de pontos de cinza (speckle tracking).

RESULTADOS:

O strain longitudinal global do ventrículo esquerdo (grupo IMD, -17 [-14,2/-20]; grupo IMF, -9 [-7/-10,7]; grupo controle, -20 [-18/-21] p < 0,001); strain circunferencial global do ventrículo esquerdo (grupo IMD, -20 [-14,5/-22,7]; grupo IMF, -10 [-7/-12]; grupo controle, -23 [-21/-27,5] p < 0,001) e strains de músculos papilares (MPP; grupo IMD, -30,5 [-24/-46,7]; grupo IMF, -18 [-12/-30]; grupo controle; -43 [-34,5/-39,5] p < 0,001; MPA; grupo IMD, (-35 [-23,5/-43]; grupo IMF, -20 [-13,5/-26]; grupo controle, -40 [-32,5/-48] p < 0,001) mostraram-se significativamente diferentes nos grupos. MPA e MPP mostraram-se altamente correlacionados com a FEVE (p < 0,001, p < 0,00; respectivamente), SLG (p < 0,001, p < 0,001; respectivamente) e SCG (p < 0,001, p < 0,001; respectivamente) do VE entre todos os grupos. Não foi encontrada correlação entre os strains de músculos papilares e área eficaz do orifício (AEO) nos grupos de insuficiência mitral grave.

CONCLUSÕES:

A medição do strain longitudinal de músculos papilares pelo método free strain é prática e aplicável. A disfunção dos músculos papilares tem um papel pequeno em IM grave devido a causas degenerativas e funcionais, e a função dos músculos papilares, em general, parece seguir a função ventricular esquerda. O MPP é o MP mais afetado na insuficiência mitral em ambos os grupos, IMD e IMF.

Fully automated software for mitral annulus evaluation in chronic mitral regurgitation by 3-dimensional transesophageal echocardiography

Three-dimensional (3D) transesophageal echocardiography (TEE) is the gold standard for mitral valve (MV) anatomic and functional evaluation. Currently, dedicated MV analysis software has limitations for its use in clinical practice. Thus, we tested here a complete and reproducible evaluation of a new fully automatic software to characterize MV anatomy in different forms of mitral regurgitation (MR) by 3D TEE.Sixty patients were included: 45 with more than moderate MR (28 organic MR [OMR] and 17 functional MR [FMR]) and 15 controls. All patients underwent TEE. 3D MV images obtained using 3D zoom were imported into the new software for automatic analysis. Different MV parameters were obtained and compared. Anatomic and dynamic differences between FMR and OMR were detected. A significant increase in systolic (859.75 vs 801.83 vs 607.78 mm; P = 0.002) and diastolic (1040.60 vs. 1217.83 and 859.74 mm; P < 0.001) annular sizes was observed in both OMR and FMR compared to that in controls. FMR had a reduced mitral annular contraction compared to degenerative cases of OMR and to controls (17.14% vs 32.78% and 29.89%; P = 0.007). Good reproducibility was demonstrated along with a short analysis time (mean 4.30 minutes).Annular characteristics and dynamics are abnormal in both FMR and OMR. Full 3D software analysis automatically calculates several significant parameters that provide a correct and complete assessment of anatomy and dynamic mitral annulus geometry and displacement in the 3D space. This analysis allows a better characterization of MR pathophysiology and could be useful in designing new devices for MR repair or replacement.

Myocardial perfusion pattern for stratification of ischemic mitral regurgitation response to percutaneous coronary intervention

OBJECTIVE

Ischemic mitral regurgitation (MR) is common, but its response to percutaneous coronary intervention (PCI) is poorly understood. This study tested the utility of myocardial perfusion imaging (MPI) for the stratification of MR response to PCI.

METHODS

MPI and transthoracic echocardiography (echo) were performed among patients undergoing PCI. MPI was used to assess stress/rest myocardial perfusion. MR was assessed via echo (performed before and after PCI).

RESULTS

A total of 317 patients with abnormal myocardial perfusion on MPI underwent echo 25±39 days before PCI. MR was present in 52%, among whom 24% had advanced (≥moderate) MR. MR was found to be associated with left ventricular (LV) chamber dilation on MPI and echo (both P<0.001). The magnitude of global LV perfusion deficits increased in relation to MR severity (P<0.01). Perfusion differences were greatest for global summed rest scores, which were 1.6-fold higher among patients with advanced MR versus those with mild MR (P=0.004), and 2.4-fold higher versus those without MR (P<0.001). In multivariate analysis, advanced MR was found to be associated with a fixed perfusion defect size on MPI [odds ratio 1.16 per segment (confidence interval 1.002-1.34), P=0.046], independent of LV volume [odds ratio 1.10 per 10 ml (confidence interval 1.04-1.17), P=0.002]. Follow-up via echo (1.0±0.6 years) demonstrated MR to decrease (≥1 grade) in 31% of patients and increase in 12% of patients. Patients with increased MR after PCI had more severe inferior perfusion defects on baseline MPI (P=0.028), whereas defects in other distributions and LV volumes were similar (P=NS).

CONCLUSION

The extent and distribution of single-photon emission computed tomography-evidenced myocardial perfusion defects impact MR response to revascularization. An increased magnitude of inferior fixed perfusion defects predicts post-PCI progression of MR.

Three-Dimensional Field Optimization Method: Clinical Validation of a Novel Color Doppler Method for Quantifying Mitral Regurgitation

BACKGROUND

Assessment of mitral regurgitation (MR) severity by echocardiography is important for clinical decision making, but MR severity can be challenging to quantitate accurately and reproducibly. The accuracy of effective regurgitant orifice area (EROA) and regurgitant volume (RVol) calculated using two-dimensional (2D) proximal isovelocity surface area is limited by the geometric assumptions of proximal isovelocity surface area shape, and both variables demonstrate interobserver variability. The aim of this study was to compare a novel automated three-dimensional (3D) echocardiographic method for calculating MR regurgitant flow using standard 2D techniques.

METHODS

A sheep model of ischemic MR and patients with MR were prospectively examined. Patients with a range of severity of MR were examined. EROA and RVol were calculated from 3D color Doppler acquisitions using a novel computer-automated algorithm based on the field optimization method to measure EROA and RVol. For an independent comparison group, the 3D field optimization method was compared with 2D methods for grading MR in an experimental ovine model of MR.

RESULTS

Fifteen 3D data sets from nine sheep (open-chest transthoracic echocardiographic data sets) and 33 transesophageal data sets from patients with MR were prospectively examined. For sheep data sets, mean 2D EROA was 0.16 ± 0.05 cm², and mean 2D RVol was 21.84 ± 8.03 mL. Mean 3D EROA was 0.09 ± 0.04 cm², and mean 3D RVol was 14.40 ± 5.79 cm³. There was good correlation between 2D and 3D EROA (R = 0.70) and RVol (R = 0.80). For patient data sets, mean 2D EROA was 0.35 ± 0.35 cm², and mean 2D RVol was 58.9 ± 52.9 mL. Mean 3D EROA was 0.34 ± 0.29 cm², and mean 3D RVol was 54.6 ± 36.5 mL. There was excellent correlation between 2D and 3D EROA (R = 0.94) and RVol (R = 0.84). Bland-Altman analysis revealed greater interobserver variability for 2D RVol measurements compared with 3D RVol using the 3D field optimization method measurements, but variability was statistically significant only for RVol.

CONCLUSIONS

Direct automated measurement of proximal isovelocity surface area region for EROA calculation using real-time 3D color Doppler echocardiography is feasible, with a high correlation to current 2D EROA methods but less variability. This novel automated method provides an accurate and highly reproducible method for calculating EROA.

Quantitative Assessment of Mitral Apparatus Geometry Using Dual-Source Computed Tomography in Mitral Regurgitation

To quantitatively assess the geometric changes in mitral valve apparatus in mitral regurgitation (MR) by dualsource computed tomography (DSCT) and to analyze its impact on MR.The study subjects consisted of 20 controls, 20 patients with mild MR, and 30 patients with moderate to severe MR, all of whom underwent DSCT. The geometric parameters of the mitral valve were measured by CT and compared among the 3 groups. The correlations between DSCT measurements and MR severity were also analyzed.As regurgitation worsened, our results showed progressive enlargements of the mitral annular area, anteroposterior diameter, and mitral valve tenting area at the central level. Moreover, a higher mitral valve sphericity index and longer distance between the heads of the papillary muscles reflected a more outward displacement of the papillary muscles. The mitral annular area and tenting area at the central level had strong correlations with regurgitation severity.DSCT is available to quantitatively assess mitral valve morphology and provide additional information regarding its geometry. The mitral annular area and tenting area at the central level were the strongest determinants of MR severity.

A maximum likelihood approach to diffeomorphic speckle tracking for 3D strain estimation in echocardiography

The strain and strain-rate measures are commonly used for the analysis and assessment of regional myocardial function. In echocardiography (EC), the strain analysis became possible using Tissue Doppler Imaging (TDI). Unfortunately, this modality shows an important limitation: the angle between the myocardial movement and the ultrasound beam should be small to provide reliable measures. This constraint makes it difficult to provide strain measures of the entire myocardium. Alternative non-Doppler techniques such as Speckle Tracking (ST) can provide strain measures without angle constraints. However, the spatial resolution and the noisy appearance of speckle still make the strain estimation a challenging task in EC. Several maximum likelihood approaches have been proposed to statistically characterize the behavior of speckle, which results in a better performance of speckle tracking. However, those models do not consider common transformations to achieve the final B-mode image (e.g. interpolation). This paper proposes a new maximum likelihood approach for speckle tracking which effectively characterizes speckle of the final B-mode image. Its formulation provides a diffeomorphic scheme than can be efficiently optimized with a second-order method. The novelty of the method is threefold: First, the statistical characterization of speckle generalizes conventional speckle models (Rayleigh, Nakagami and Gamma) to a more versatile model for real data. Second, the formulation includes local correlation to increase the efficiency of frame-to-frame speckle tracking. Third, a probabilistic myocardial tissue characterization is used to automatically identify more reliable myocardial motions. The accuracy and agreement assessment was evaluated on a set of 16 synthetic image sequences for three different scenarios: normal, acute ischemia and acute dyssynchrony. The proposed method was compared to six speckle tracking methods. Results revealed that the proposed method is the most accurate method to measure the motion and strain with an average median motion error of 0.42 mm and a median strain error of 2.0 ± 0.9%, 2.1 ± 1.3% and 7.1 ± 4.9% for circumferential, longitudinal and radial strain respectively. It also showed its capability to identify abnormal segments with reduced cardiac function and timing differences for the dyssynchrony cases. These results indicate that the proposed diffeomorphic speckle tracking method provides robust and accurate motion and strain estimation.

Echocardiographic assessment of ischemic mitral regurgitation

Ischemic mitral regurgitation is an important consequence of LV remodeling after myocardial infarction. Echocardiographic diagnosis and assessment of ischemic mitral regurgitation are critical to gauge its adverse effects on prognosis and to attempt to tailor rational treatment strategy. There is no single approach to the echocardiographic assessment of ischemic mitral regurgitation: standard echocardiographic measures of mitral regurgitation severity and of LV dysfunction are complemented by assessments of displacement of the papillary muscles and quantitative indices of mitral valve deformation. Development of novel approaches to understand mitral valve geometry by echocardiography may improve understanding of the mechanism, clinical trajectory, and reparability of ischemic mitral regurgitation.

Temporal changes in interpapillary muscle dynamics as an active indicator of mitral valve and left ventricular interaction in ischemic mitral regurgitation

BACKGROUND

Regional subpapillary myocardial hypokinesis may impair lateral reduction in the interpapillary muscle distance (IPMD) from diastole to systole, and adversely affect mitral valve geometry and tethering.

OBJECTIVES

The goal of this study was to investigate the impact of impaired lateral shortening in the interpapillary muscle distance on mitral valve geometry and function in ischemic heart disease.

METHODS

To quantify ventricular size/shape, regional myocardial contraction, lateral shortening of the IPMD, mitral valve geometry, and severity of mitral regurgitation, 67 patients with ischemic heart disease underwent cardiac magnetic resonance imaging, and a correlation analysis of measured parameters was performed. The impact of reduced IPMD shortening on mitral valve (dys)function was confirmed in swine and in a physiological computational mitral valve model.

RESULTS

Lateral shortening of the IPMD from diastole to systole was severely reduced in patients with moderate/severe ischemic mitral regurgitation (9.6 ± 2.8 mm), but preserved in mild IMR (11.5 ± 3.4 mm). Left ventricular size and ejection fraction did not differ between the groups. In swine with subpapillary infarction and impaired IPMD, mitral regurgitation was evident within 1 week, compared to those pigs with a nonpapillary infarction and preserved IPMD. In the controlled computational valve model, IPMD had the maximal impact on regurgitation, and was exacerbated with additional annular dilation.

CONCLUSIONS

By using cardiac magnetic resonance imaging in humans, we demonstrated that it is the impairment of lateral shortening between the papillary muscles, and not passive ventricular size, that governs the severity of mitral regurgitation. Loss of lateral shortening of IPMD tethers the leaflet edges and impairs their systolic closure, resulting in mitral regurgitation, even in small ventricles. Understanding the lateral dynamics of ventricular-valve interactions could aid the development of new repair techniques for ischemic mitral regurgitation.

Effect of myocardial perfusion pattern on frequency and severity of mitral regurgitation in patients with known or suspected coronary artery disease

Mitral regurgitation (MR) is common with coronary artery disease as altered myocardial substrate can affect valve performance. Single-photon emission computed tomography myocardial perfusion imaging (MPI) enables assessment of myocardial perfusion alterations. This study examined perfusion pattern in relation to MR. A total of 2,377 consecutive patients with known or suspected coronary artery disease underwent stress MPI and echocardiography within 1.6 ± 2.3 days. MR was present on echocardiography in 34% of patients, among whom 13% had advanced (moderate or more) MR. MR prevalence was higher in patients with abnormal MPI (44% vs 29%, p <0.001), corresponding to increased global ischemia (p <0.001). Regional perfusion varied in left ventricular segments adjacent to each papillary muscle: adjacent to the anterolateral papillary muscle, magnitude of baseline and stress-induced anterior/anterolateral perfusion abnormalities was greater in patients with MR (both p <0.001). Adjacent to the posteromedial papillary muscle, baseline inferior/inferolateral perfusion abnormalities were greater with MR (p <0.001), whereas stress inducibility was similar (p = 0.39). In multivariate analysis, stress-induced anterior/anterolateral and rest inferior/inferolateral perfusion abnormalities were independently associated with MR (both p <0.05) even after controlling for perfusion in reference segments not adjacent to the papillary muscles. MR severity increased in relation to magnitude of perfusion abnormalities in each territory adjacent to the papillary muscles, as evidenced by greater prevalence of advanced MR in patients with at least moderate anterior/anterolateral stress perfusion abnormalities (10.7% vs 3.6%), with similar results when MR was stratified based on rest inferior/inferolateral perfusion (10.4% vs 3.0%, both p <0.001). In conclusion, findings demonstrate that myocardial perfusion pattern in left ventricular segments adjacent to the papillary muscles influences presence and severity of MR.

Clinical application of three-dimensional echocardiography

Echocardiography is one of the most valuable diagnostic tools in cardiology. Technological advances in ultrasound, computer and electronics enables three-dimensional (3-D) imaging to be a clinically viable modality which has significant impact on diagnosis, management and interventional procedures. Since the inception of 3D fully-sampled matrix transthoracic and transesophageal technology it has enabled easier acquisition, immediate on-line display, and availability of on-line analysis for the left ventricle, right ventricle and mitral valve. The use of 3D TTE has mainly focused on mitral valve disease, left and right ventricular volume and functional analysis. As structural heart disease procedures become more prevalent, 3D TEE has become a requirement for preparation of the procedure, intra-procedural guidance as well as monitoring for complications and device function. We anticipate that there will be further software development, improvement in image quality and workflow.

Mitral apparatus assessment by delayed enhancement CMR: relative impact of infarct distribution on mitral regurgitation

OBJECTIVES

This study sought to assess patterns and functional consequences of mitral apparatus infarction after acute myocardial infarction (AMI).

BACKGROUND

The mitral apparatus contains 2 myocardial components: papillary muscles and the adjacent left ventricular (LV) wall. Delayed-enhancement cardiac magnetic resonance (DE-CMR) enables in vivo study of inter-relationships and potential contributions of LV wall and papillary muscle infarction (PMI) to mitral regurgitation (MR).

METHODS

Multimodality imaging was performed: CMR was used to assess mitral geometry and infarct pattern, including 3D DE-CMR for PMI. Echocardiography was used to measure MR. Imaging occurred 27 ± 8 days after AMI (CMR, echocardiography within 1 day).

RESULTS

A total of 153 patients with first AMI were studied; PMI was present in 30% (n = 46 [72% posteromedial, 39% anterolateral]). When stratified by angiographic culprit vessel, PMI occurred in 65% of patients with left circumflex, 48% with right coronary, and only 14% of patients with left anterior descending infarctions (p <0.001). Patients with PMI had more advanced remodeling as measured by LV size and mitral annular diameter (p <0.05). Increased extent of PMI was accompanied by a stepwise increase in mean infarct transmurality within regional LV segments underlying each papillary muscle (p <0.001). Prevalence of lateral wall infarction was 3-fold higher among patients with PMI compared to patients without PMI (65% vs. 22%, p <0.001). Infarct distribution also impacted MR, with greater MR among patients with lateral wall infarction (p = 0.002). Conversely, MR severity did not differ on the basis of presence (p = 0.19) or extent (p = 0.12) of PMI, or by angiographic culprit vessel. In multivariable analysis, lateral wall infarct size (odds ratio 1.20/% LV myocardium [95% confidence interval: 1.05 to 1.39], p = 0.01) was independently associated with substantial (moderate or greater) MR even after controlling for mitral annular (odds ratio 1.22/mm [1.04 to 1.43], p = 0.01), and LV end-diastolic diameter (odds ratio 1.11/mm [0.99 to 1.23], p = 0.056).

CONCLUSIONS

Papillary muscle infarction is common after AMI, affecting nearly one-third of patients. Extent of PMI parallels adjacent LV wall injury, with lateral infarction-rather than PMI-associated with increased severity of post-AMI MR.

Anatomy of the mitral valve apparatus: role of 2D and 3D echocardiography

The mitral valve apparatus is a complex 3-dimensional (3D) functional unit that is critical to unidirectional heart pump function. This review details the normal anatomy, histology, and function of the main mitral valve apparatus components: mitral annulus, mitral valve leaflets, chordae tendineae, and papillary muscles. Two-dimensional and 3D echocardiography is ideally suited to examine the mitral valve apparatus and has provided important insights into the mechanism of mitral valve disease. An overview of standardized echocardiography image acquisition and interpretation is provided. Understanding normal mitral valve apparatus function is essential to comprehend alterations in mitral valve disease and the rationale for repair strategies.

Quantitation of the mitral tetrahedron in patients with ischemic heart disease using real-time three-dimensional echocardiography to evaluate the geometric determinants of ischemic mitral regurgitation

BACKGROUND

Ischemic mitral regurgitation (IMR) is common in ischemic heart disease and results in poor prognosis. However, the exact mechanism of IMR has not been fully elucidated.

HYPOTHESIS

Quantitation of the mitral tetrahedron using three-dimentianl (3D) echocardiography is capable of evaluating the geometric determinants and mechanisms of IMR.

METHODS

Forty patients with a history of ST-elevation myocardial infarction at least 6 months earlier were studied. Parameters of mitral deformation and global left ventricular (LV) function and shape were evaluated by 2-dimensional echocardiography. The effective regurgitant orifice (ERO) of IMR was obtained by the quantitative continuous-wave Doppler technique. Three-dimensional (3D) echocardiography was applied to assess the mitral tetrahedron.

RESULTS

Mitral valvular tenting area (P < 0.001), mitral annular area (P = 0.032), dilation of the LV in diastole, impairment of the LV ejection fraction, and volume of the spherically shaped LV in systole were greater in patients with an ERO ≥20 mm(2) than in those with an ERO <20 mm(2). In the mitral tetrahedron, only the interpapillary muscle roots distance showed a significant difference (P = 0.004). Multivariate analysis with the logistic regression model showed the systolic mitral tenting area (odds ratio [OR]: 280.49, 95% confidence interval [CI]: 4.59-1.72 × 10(4), P = 0.007) and interpapillary muscle distance (OR: 1.50, 95% CI: 1.03-2.19, P = 0.036) to be independent factors in predicting significant IMR (ERO ≥20 mm(2)).

CONCLUSIONS

3D echocardiography can be effectively applied in measuring the mitral tetrahedron and evaluating the mechanism of IMR. Mitral valvular tenting and interpapillary muscle distance are 2 independent factors of significant IMR.

Ischaemic mitral regurgitation: pathophysiology, outcomes and the conundrum of treatment

Ischaemic mitral regurgitation is a frequent complication of left ventricular global or regional pathological remodelling due to chronic coronary artery disease. It is not a valve disease but represents the valvular consequences of increased tethering forces (papillary muscles displacement leading to a more apical position of the leaflets and their coaptation point) and reduced closing forces (reduced contractility, dyssynchrony of the papillary muscles, intra-left ventricular dyssynchrony). Although mitral regurgitation has an unloading effect and reduces impedance, the volume overload begets further left ventricular dilatation, increases ventricular wall stress leading to worsened performance. Ischaemic mitral regurgitation is characteristically dynamic: its severity may vary with haemodynamic conditions. Both the severity of ischaemic mitral regurgitation and its dynamic component worsen prognosis. There are numerous possible treatment modalities, but the management of the individual patient remains difficult. Medical therapy is mandatory; revascularization procedures are frequently not sufficient to reduce mitral regurgitation; the role of combined surgical therapy by mitral valve repair is not yet defined in the absence of large randomized trial. Some patients are good candidates for cardiac resynchronization therapy that may reduce the amount of regurgitation. New therapeutic targets are under investigation.

Clinical significance of papillary muscle late enhancement detected via cardiac magnetic resonance imaging in patients with single old myocardial infarction

BACKGROUND

Contrast-enhanced cardiac magnetic resonance imaging (MRI) can depict papillary muscle (PM) necrosis or fibrosis by late enhancement (LE) of PM, but its clinical significance in old myocardial infarction (OMI) has been little understood.

METHODS

Myocardial LE and PM-LE were detected with contrast imaging in 60 patients with OMI caused by a single culprit coronary artery lesion. Left ventricular (LV) morphology and function, mitral valve geometry, and severity of mitral regurgitation were also evaluated by cine imaging. Sphericity index was calculated for the assessment of LV remodeling.

RESULTS

PM-LE was detected in 32 of 60 (53.3%) OMI patients. Unilateral PM-LE was detected in 22 patients and bilateral PM-LE in 10 patients. Patients with bilateral PM-LE demonstrated more severe LV remodeling and functional mitral regurgitation than those with unilateral or no PM-LE (sphericity index; bilateral PM-LE, 1.60±0.15, unilateral PM-LE, 1.71±0.29, no PM-LE, 1.85±0.27, p≤0.05) (mitral regurgitation; bilateral PM-LE, 1.10±0.57, unilateral PM-LE, 0.41±0.73, no PM-LE, 0.54±0.84, p≤0.05). In cases of unilateral PM-LE, posteromedial PM-LE resulting from right coronary artery-related OMI was accompanied by less severe mitral regurgitation, while anterolateral PM-LE resulting from left coronary artery-related OMI was not associated with severity of mitral regurgitation.

CONCLUSIONS

More than half of patients with OMI showed unilateral or bilateral PM-LE, and bilateral PM-LE was closely related to more severe LV remodeling and functional mitral regurgitation.

The effect of pure mitral regurgitation on mitral annular geometry and three-dimensional saddle shape

OBJECTIVE

Chronic ischemic mitral regurgitation is associated with mitral annular dilatation in the septal-lateral dimension and flattening of the annular 3-dimensional saddle shape. To examine whether these perturbations are caused by the ischemic insult, mitral regurgitation, or both, we investigated the effects of pure mitral regurgitation (low pressure volume overload) on annular geometry and shape.

METHODS

Eight radiopaque markers were sutured evenly around the mitral annulus in sheep randomized to control (CTRL, n = 8) or experimental (HOLE, n = 12) groups. In HOLE, a 3.5- to 4.8-mm hole was punched in the posterior leaflet to generate pure mitral regurgitation. Four-dimensional marker coordinates were obtained radiographically 1 and 12 weeks postoperatively. Mitral annular area, annular septal-lateral and commissure-commissure dimensions, and annular height were calculated every 16.7 ms.

RESULTS

Mitral regurgitation grade was 0.4 +/- 0.4 in CTRL and 3.0 +/- 0.8 in HOLE (P < .001) at 12 weeks. End-diastolic left ventricular volume index was greater in HOLE at both 1 and 12 weeks; end-systolic volume index was larger in HOLE at 12 weeks. Mitral annular area increased in HOLE predominantly in the commissure-commissure dimension, with no difference in annular height between HOLE versus CTRL at 1 or 12 weeks, respectively.

CONCLUSION

In contrast with annular septal-lateral dilatation and flattening of the annular saddle shape observed with chronic ischemic mitral regurgitation, pure mitral regurgitation was associated with commissure-commissure dimension annular dilatation and no change in annular shape. Thus, infarction is a more important determinant of septal-lateral dilatation and annular shape than mitral regurgitation, which reinforces the need for disease-specific designs of annuloplasty rings.

Quantification of Mitral Apparatus Dynamics in Functional and Ischemic Mitral Regurgitation Using Real-time 3-Dimensional Echocardiography

Mitral regurgitation (MR) in dilated cardiomyopathy (DCM-MR) and MR in ischemic cardiomyopathy (ISC-MR) usually occurs as a result of mitral annulus (MA) dilatation and papillary muscle displacement secondary to global left ventricle remodelling. We propose a method to determine MA area and motion throughout the cardiac cycle and to define papillary muscle position in 3-dimensional space using real-time 3-dimensional echocardiography. Real-time 3-dimensional echocardiography was performed in 24 healthy individuals, and in 30 patients with DCM-MR (n = 15) or ISC-MR (n = 15). Significant intergroup differences were noted in MA surface area (control: 6.4 +/- 1.7 cm(2); DCM-MR: 11.1 +/- 2.6 cm(2); ISC-MR: 9.0 +/- 2.0 cm(2)) and in peak MA motion (control: 8.7 +/- 3.0 mm; DCM-MR: 3.4 +/- 1.7 mm; ISC-MR: 4.9 +/- 1.5 mm). In patients with DCM-MR, papillary muscle symmetry was preserved, whereas in patients with ISC-MR, papillary tethering lengths were unequal as a result of wall-motion abnormalities. Our methodology for dynamic volumetric measurements of the mitral apparatus allows better understanding of MR mechanisms.

Effects of acute ischemic mitral regurgitation on three-dimensional mitral leaflet edge geometry

BACKGROUND

Improved quantitative understanding of in vivo leaflet geometry in ischemic mitral regurgitation (IMR) is needed to improve reparative techniques, yet few data are available due to current imaging limitations. Using marker technology we tested the hypotheses that IMR (1) occurs chiefly during early systole; (2) affects primarily the valve region contiguous with the myocardial ischemic insult; and (3) results in systolic leaflet edge restriction.

METHODS

Eleven sheep had radiopaque markers sutured as five opposing pairs along the anterior (A(1)-E(1)) and posterior (A(2)-E(2)) mitral leaflet free edges from the anterior commissure (A(1)-A(2)) to the posterior commissure (E(1)-E(2)). Immediately postoperatively, biplane videofluoroscopy was used to obtain 4D marker coordinates before and during acute proximal left circumflex artery occlusion. Regional mitral orifice area (MOA) was calculated in the anterior (Ant-MOA), middle (Mid-MOA), and posterior (Post-MOA) mitral orifice segments during early systole (EarlyS), mid systole (MidS), and end systole (EndS). MOA was normalized to zero (minimum orifice opening) at baseline EndS. Tenting height was the distance of the midpoint of paired markers to the mitral annular plane at EndS.

RESULTS

Acute ischemia increased echocardiographic MR grade (0.5+/-0.3 vs 2.3+/-0.7, p<0.01) and MOA in all regions at EarlyS, MidS, and EndS: Ant-MOA (7+/-10 vs 22+/-19 mm(2), 1+/-2 vs 18+/-16 mm(2), 0 vs 17+/-15 mm(2)); Mid-MOA (9+/-13 vs 25+/-17 mm(2), 3+/-6 vs 21+/-19 mm(2), 0 vs 25+/-17 mm(2)); and Post-MOA (8+/-10 vs 25+/-16, 2+/-4 vs 22+/-13 mm(2), 0 vs 23+/-13 mm(2)), all p<0.05. There was no change in MOA throughout systole (EarlyS vs MidS vs EndS) during baseline conditions or ischemia. Tenting height increased with ischemia near the central and the anterior commissure leaflet edges (B(1)-B(2): 7.1+/-1.8mm vs 7.9+/-1.7 mm, C(1)-C(2): 6.9+/-1.3mm vs 8.0+/-1.5mm, both p<0.05).

CONCLUSIONS

MOA during ischemia was larger throughout systole, indicating that acute IMR in this setting is a holosystolic phenomenon. Despite discrete postero-lateral myocardial ischemia, Post-MOA was not disproportionately larger. Acute ovine IMR was associated with leaflet restriction near the central and the anterior commissure leaflet edges. This entire constellation of annular, valvular, and subvalvular ischemic alterations should be considered in the approach to mitral repair for IMR.