An integrated mechanism for systolic anterior motion of the mitral valve in hypertrophic cardiomyopathy based on echocardiographic observations

Morphological anomalies in obstructive hypertrophic cardiomyopathy: Insights from four-dimensional computed tomography and surgical correlation

Hypertrophic cardiomyopathy (HCM) is a genetic disorder in which left ventricular outflow tract obstruction critically affects symptoms and prognosis. Traditionally, left ventricular outflow tract obstruction was primarily attributed to septal hypertrophy with systolic anterior motion of the mitral valve. However, recent evidence highlights significant contributions from the mitral valve and papillary muscle anomalies, as well as an apical-basal muscle bundle observed in HCM patients. Accurate morphological assessment is essential when considering septal reduction therapy. While transesophageal echocardiography and cardiac magnetic resonance are recommended for assessing the anomalous structures, four-dimensional computed tomography offers superior spatial resolution and multiplanar reconstruction capabilities. These features enable the evaluation of details of the morphological anomalies, such as the apical-basal muscle band, papillary muscle anomalies, subaortic stenosis, and right ventricular outflow tract obstruction. Based on the detailed assessment of these morphological features, four-dimensional computed tomography has been utilized for planning of surgical correction in a comprehensive HCM center. This approach facilitates the intervention strategies and may improve outcomes in septal reduction therapy for obstructive HCM.

Obstruction in Hypertrophic Cardiomyopathy: Many Faces

Hypertrophic cardiomyopathy (HCM), the most common inherited cardiomyopathy, exhibits left ventricular hypertrophy not secondary to other causes, with varied phenotypic expression. Enhanced actin-myosin interaction underlies excessive myocardial contraction, frequently resulting in dynamic obstruction within the left ventricle. Left ventricular outflow tract obstruction, occurring at rest or with provocation in 75% of HCM patients, portends adverse prognosis, contributes to symptoms, and is frequently a therapeutic target. Transthoracic echocardiography plays a crucial role in the screening, initial diagnosis, management, and risk stratification of HCM. Herein, we explore echocardiographic evaluation of HCM, emphasizing Doppler assessment for obstruction. Echocardiography informs management strategies through noninvasive hemodynamic assessment, which is frequently obtained with various provocative maneuvers. Recognition of obstructive HCM phenotypes and associated anatomical abnormalities guides therapeutic decision-making. Doppler echocardiography allows monitoring of therapeutic responses, whether it be medical therapies (including cardiac myosin inhibitor therapy) or septal reduction therapies, including surgical myectomy and alcohol septal ablation. This article discusses the hemodynamics of obstruction and practical application of Doppler assessment in HCM. In addition, it provides a visual atlas of obstruction in HCM, including high-quality figures and complementary videos that illustrate the many facets of dynamic obstruction.

Frequent POCUS and auscultation for an earlier diagnosis of takotsubo syndrome and unraveling of its pathophysiology: The possible crucial role of LVOTO

There is ample literature associating LVOTO with hypertension, AMI, LV hypertrophy, sigmoid septum, HCM, and TTS, particularly in midde aged/elderly/postmenopausal women, suggestive of a causal role for LVOTO in the pathophysiology of TTS. Although there is significant evidence that TTS is triggered by a sudden autonomic sympathetic nervous system surge and/or elevated blood-ridden catecholamines, the exact pathophysiologic trajectory leading to the clinical expression of the disease is still being debated. This review expounds on the possibility that LVOTO is a causal early component of this trajectory, and proposes that TTS is a malady within the broad spectrum of the myocardial ischemic injury/stunned myocardium states. The postulated underlying mechanism by which LVOTO causes TTS is a sudden abterload rise, with resultant oxygen/energy supply/demand mismatch, leading to a transient myocardial ischemia/injury myocardial stunning state. This needs to be explored painstakingly, and this review includes some suggestions for such undertaking. Ellucidation of the pathophysiology of TTS, and possible proof about a mechanistic role of LVOTO, may ensure that our current pharmacological and device panoply is adequate for the management of TTS.

Extended septal myectomy for obstructive hypertrophic cardiomyopathy and its impact on mitral valve function

AIMS

Septal myectomy is the treatment of choice for hypertrophic obstructive cardiomyopathy (HOCM). Around 30-60% of patients with HOCM have a secondary mitral valve regurgitation due to systolic anterior motion (SAM). We report our experience with extended septal myectomy and its impact on the incidence of concomitant mitral valve procedures.

METHODS

This is a retrospective study on 84 patients who underwent SM from January 2008 to February 2022. Surgical procedure was performed according to the concept of 'extended myectomy' described by Messmer in 1994. Follow-up outcomes in terms of survival, hospital admissions for heart failure or MV disease, cardiac reoperations, and pacemaker (PMK) implantation were recorded.

RESULTS

Mean age was 61 ± 15 years. Mitral valve surgery was performed in seven cases (8%); particularly only one patient without degenerative mitral valve disease underwent mitral valve surgery, with a plicature of the posterior leaflet. In-hospital mortality was 5%. Mitral valve regurgitation greater than mild was present in four patients (5%) at discharge. Twelve-year survival was 78 ± 22%. Cumulative incidence of rehospitalization for heart failure and rehospitalization for mitral valve disease was 10 ± 4 and 2.5 ± 2.5%, respectively. PMK implantation was 5% at discharge, with a cumulative incidence of 15 ± 7%. Freedom from cardiac reoperations was 100%.

CONCLUSION

Septal myectomy for HOCM is associated with good outcomes. Although concomitant surgery on the mitral valve to address SAM and associated regurgitation has been advocated, these procedures were needed in our practice only in patients with intrinsic mitral valve disease. Adequate myectomy addresses the underlying pathophysiology in most patients.

Role of Imaging in the Diagnosis, Evaluation, and Management of Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is increasingly recognized and may benefit from the recent approval of new, targeted medical therapy. Successful management of HCM is dependent on early and accurate diagnosis. The lack of a definitive diagnostic test, the wide variation in phenotype and the commonness of phenocopy conditions, and the presence of normal or hyperdynamic left ventricular function in most patients makes HCM a condition that is highly dependent on imaging for all aspects of management including, diagnosis, classification, predicting risk of complications, detecting complications, identifying risk for ventricular arrhythmias, evaluating choice of therapy and monitoring therapy, intraprocedural guidance, and screening family members. Although echocardiographic imaging remains the mainstay in the diagnosis and subsequent management of HCM, this disease clearly requires multimethod imaging for various aspects of optimal patient care. Advances in echocardiography hardware and techniques, development and refinement of imaging with computed tomography, magnetic resonance, and nuclear scanning, and the emergence of very focused assessments such as diastology and fibrosis imaging have all advanced the diagnosis and management of HCM. In this review, we discuss the relative utility and evidence support for these imaging approaches to contribute to improve patient outcomes.

Preoperative evaluation of systolic murmur with point-of-care echocardiography before an elective thoracic surgery - A case report

BACKGROUND

Systolic murmur suggesting the association of aortic valve (AV) stenosis or obstructive pathology in the left ventricular outflow tract (LVOT) usually requires preoperative echocardiographic evaluation for elective surgery.

CASE

In a 63-year-old female patient undergoing elective thoracic surgery, the systolic murmur was auscultated on the right sternal border of the second intercostal space in the preoperative patient holding area. Point-of-care (POC) transthoracic echocardiography (TTE) demonstrated a systolic jet flow in the LVOT area. The peak systolic velocity of the continuous wave Doppler tracing, aligned to the LVOT and the AV, was approximately 1.5 m/s. The peak/mean pressure gradient was 11/6 mmHg for the AV and 9/5 mmHg for the LVOT. Anesthesia was induced under continuous TTE imaging. Intraoperative transesophageal echocardiography also confirmed the absence of any cardiac pathology.

CONCLUSIONS

POC echocardiography offered a thorough preoperative evaluation of an unexpectedly identified systolic murmur, avoiding a potential delay in the operation schedule for conventional preoperative echocardiographic evaluation.

Systolic anterior motion of the anterior mitral valve leaflet begins in subclinical hypertrophic cardiomyopathy

AIMS

Anterior mitral valve leaflet (AMVL) elongation is detectable in overt and subclinical hypertrophic cardiomyopathy (HCM). We sought to investigate the dynamic motion of the aorto-mitral apparatus to understand the behaviour of the AMVL and the mechanisms of left ventricular outflow tract obstruction (LVOTO) predisposition in HCM.

METHODS AND RESULTS

Cardiovascular magnetic resonance imaging using a 1.5 Tesla scanner was performed on 36 HCM sarcomere gene mutation carriers without left ventricular hypertrophy (G+LVH-), 31 HCM patients with preserved ejection fraction carrying a pathogenic sarcomere gene mutation (G+LVH+), and 53 age-, sex-, and body surface area-matched healthy volunteers. Dynamic excursion of the aorto-mitral apparatus was assessed semi-automatically on breath-held three-chamber cine steady-state free precession images. Four pre-defined regions of interest (ROIs) were tracked: ROIPMVL: hinge point of the posterior mitral valve leaflet; ROITRIG: intertrigonal mitral annulus; ROIAMVL: AMVL tip; and ROIAAO: anterior aortic annulus. Compared with controls, normalized two-dimensional displacement-vs.-time plots in G+LVH- revealed subtle but significant systolic anterior motion (SAM) of the AMVL (P < 0.0001) and reduced longitudinal excursion of ROIAAO (P = 0.014) and ROIPMVL (P = 0.048). In overt and subclinical HCM, excursion of the ROITRIG/AMVL/PMVL was positively associated with the burden of left ventricular fibrosis (P < 0.028). As expected, SAM was observed in G+LVH+ together with reduced longitudinal excursion of ROITRIG (P = 0.049) and ROIAAO (P = 0.008).

CONCLUSION

Dyskinesia of the aorto-mitral apparatus, including SAM of the elongated AMVL, is detectable in subclinical HCM before the development of LVH or left atrial enlargement. These data have the potential to improve our understanding of early phenotype development and LVOTO predisposition in HCM.

Obstructive Hypertrophic Cardiomyopathy and Takotsubo Syndrome: How to Deal With Left Ventricular Ballooning?

Currently, there are 2 proposed causes of acute left ventricular ballooning. The first is the most cited hypothesis that ballooning is caused by direct catecholamine toxicity on cardiomyocytes or by microvascular ischemia. We refer to this pathogenesis as Takotsubo syndrome. More recently, a second cause has emerged: that in some patients with underlying hypertrophic cardiomyopathy, left ventricular ballooning is caused by the sudden onset of latent left ventricular outflow tract obstruction. When it becomes severe and unrelenting, severe afterload mismatch and acute supply-demand ischemia appear and result in ballooning. In the context of 2 causes, presentations might overlap and cause confusion. Knowing the pathophysiology of each mechanism and how to determine a correct diagnosis might guide treatment.

The Role of the Submitral Apparatus in Hypertrophic Obstructive Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiovascular disease, is characterized by unexplained hypertrophy of any myocardial segment, and has a prevalence of 0.2% to 0.5% among the general population. As one of the phenotypes of hypertrophic cardiomyopathy, left ventricular outflow tract obstruction (LVOTO) is associated with high morbidity and mortality, including cardiac death. The integration of various factors, including septal hypertrophy, malformation of the mitral valve apparatus, and an anomalous mitral subvalvular apparatus, may contribute to the occurrence of LVOTO. Previous studies have thoroughly discussed the role of the mitral valve in the mechanisms of systolic anterior motion and LVOTO. Recent studies have shown the importance of determining the potential mechanism of the submitral apparatus in inducing systolic anterior motion and LVOTO. The authors review recent advances in knowledge regarding the submitral apparatus of patients with hypertrophic cardiomyopathy.

Multimodality Imaging in Sarcomeric Hypertrophic Cardiomyopathy: Get It Right…on Time

Hypertrophic cardiomyopathy (HCM) follows highly variable paradigms and disease-specific patterns of progression towards heart failure, arrhythmias and sudden cardiac death. Therefore, a generalized standard approach, shared with other cardiomyopathies, can be misleading in this setting. A multimodality imaging approach facilitates differential diagnosis of phenocopies and improves clinical and therapeutic management of the disease. However, only a profound knowledge of the progression patterns, including clinical features and imaging data, enables an appropriate use of all these resources in clinical practice. Combinations of various imaging tools and novel techniques of artificial intelligence have a potentially relevant role in diagnosis, clinical management and definition of prognosis. Nonetheless, several barriers persist such as unclear appropriate timing of imaging or universal standardization of measures and normal reference limits. This review provides an overview of the current knowledge on multimodality imaging and potentialities of novel tools, including artificial intelligence, in the management of patients with sarcomeric HCM, highlighting the importance of specific "red alerts" to understand the phenotype-genotype linkage.

Is anterior mitral valve leaflet length important in outcome of septal myectomy for obstructive hypertrophic cardiomyopathy?

OBJECTIVES

Elongation of mitral valve leaflets is a phenotypic feature of hypertrophic cardiomyopathy, and some surgeons advocate plication of the anterior leaflet at the time of septal myectomy. The present study investigates mitral valve leaflet length and outcomes of patients undergoing septal myectomy for obstructive hypertrophic cardiomyopathy.

METHODS

We reviewed the records and echocardiograms of 564 patients who underwent transaortic septal myectomy for obstructive hypertrophic cardiomyopathy between February 2015 and April 2018. Extended septal myectomy without plication of the anterior leaflet was the standard procedure. From intraoperative prebypass transesophageal echocardiograms, we measured anterior and posterior mitral valve leaflets and their coaptation length. For comparison, we performed these mitral valve leaflet measurements in 90 patients who underwent isolated coronary artery bypass grafting and 92 patients undergoing aortic valve replacement in the same period. Among patients with hypertrophic cardiomyopathy undergoing septal myectomy, we assessed left ventricular outflow tract gradient relief and 1-year survival in relation to leaflet length.

RESULTS

Median patient age (interquartile range) was 60.3 (50.2-67.7) years, and 54.1% were male. Concomitant mitral valve repair was performed in 36 patients (6.4%), and mitral valve replacement was performed in 8 patients (1.4%), primarily for intrinsic mitral valve disease. Patients in the hypertrophic cardiomyopathy cohort had significantly longer mitral valve leaflet measurements compared with patients undergoing coronary artery bypass grafting or aortic valve replacement (P < .001 for all 3 measurements). Preoperative resting left ventricular outflow tract gradients were not related to leaflet length (<30 mm, median 49 [21, 81.5] mm Hg vs ≥30 mm, 50.5 [21, 77] mm Hg; P = .76). Further, gradient reduction after myectomy was not related to leaflet length; patients with less than 30 mm anterior leaflet length had a median gradient reduction of 33 (69, 6) mm Hg compared with 36.5 (62, 6) mm Hg for patients with leaflet length 30 mm or more (P = .36). Anterior mitral valve leaflet length was not associated with increased 1-year mortality (P = .758).

CONCLUSIONS

Our study confirms previous findings that patients with hypertrophic cardiomyopathy have slight (5 mm) elongation of mitral valve leaflets. In contrast to other reports, increased anterior mitral valve leaflet length was not associated with higher left ventricular outflow tract gradients. Importantly, we found no significant relationship between anterior mitral valve leaflet length and postoperative left ventricular outflow tract resting gradients or gradient relief. Thus, in the absence of intrinsic mitral valve disease, transaortic septal myectomy with focus on extending the excision beyond the point of septal contact is sufficient for almost all patients.

Prevalence and Prognosis of Atenolol-Responsive Systolic Anterior Motion of the Septal Mitral Valve Leaflet in Young Cats with Severe Dynamic Left Ventricular Outflow Tract Obstruction

BACKGROUND

Severe dynamic left ventricular outflow tract obstruction (DLVOTO) secondary to the systolic anterior motion of the septal mitral valve leaflet (SAM) can result either from congenital mitral valve disorders or left ventricular concentric hypertrophy of any cause, in cats commonly hypertrophic cardiomyopathy (HCM). Though HCM cannot be reversed, the question remains whether atenolol can cure cats with severe DLVOTO resulting from a presumed mitral valve dysplasia.

METHODS

In this retrospective case series, client-owned asymptomatic cats younger than 1.5 years with echocardiographic evidence of SAM and severe DLVOTO were included. Oral atenolol therapy and recheck echocardiography after 2-3 months were recommended. The owners and referring veterinarians were called for long-term follow-up information.

RESULTS

Of the 28 included cats, 23 were treated with atenolol. Recheck echocardiography performed in 17 cats showed a resolution of SAM in 47%. In the long term, SAM remained absent in only 9% of the treated cats. Cardiac-related death occurred in 26% of the atenolol-treated cats.

CONCLUSIONS

The long term benefit of twice-daily atenolol therapy was documented in 9% of cats. Whether the cats where atenolol failed to resolve DLVOTO on long-term had HCM, or a therapy-resistant congenital primary mitral valve disorder remains unclear.

Impact of secondary mitral valve chordal cutting on valve geometry in obstructive hypertrophic cardiomyopathy with marked septal hypertrophy

AIMS

In patients with obstructive hypertrophic cardiomyopathy (HCM) and mild septal thickness undergoing myectomy, resecting fibrotic anterior mitral leaflet (AML) secondary chordae moves the mitral valve (MV) away from the outflow tract and ejection flow, reducing the need for a deep septal excision. Aim of the present study was to assess whether chordal resection has similarly favourable effects in patients with important hypertrophy, who represent the majority of patients with obstructive HCM.

METHODS AND RESULTS

The MV position in the ventricular cavity, assessed from echocardiography as AML-annulus ratio, was compared before and after chordal resection in 150 consecutive HCM patients with important (≥20 mm) and 62 with mild (≤19 mm) septal thickness undergoing myectomy. Preoperatively, MV position was displaced towards the septum to a similar extent in both groups. Postoperatively, AML-annulus ratio increased of an equal degree in both groups, from 0.43 ± 0.05 to 0.55 ± 0.06 (P < 0.001) a 28% increase, and from 0.43 ± 0.06 to 0.55 ± 0.06 (P < 0.001) a 26% increase, respectively, indicating a similar MV shift away from the outflow tract. When AML-annulus ratio was compared in the study cohort and 124 normal subjects, MV position was within normal range in <4% of patients preoperatively and normalized in >50% postoperatively.

CONCLUSIONS

In obstructive HCM, displacement of the MV apparatus into the outflow tract interferes with the ejection flow. Resection of fibrotic secondary chordae moves the MV apparatus away from the outflow tract and enlarges the outflow area independently of septal thickness, facilitating septal myectomy by reducing the need for a deep muscular excision.

Treatment of Severe Left Ventricular Outflow Tract Obstruction and Mitral Regurgitation With Alcohol Septal Ablation

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Hypertrophic cardiomyopathy is a common genetic heart disease.

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Patients can have variable clinical manifestations and severity of disease.

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Manifestations include LVOT obstruction and MR.

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Alcohol septal ablation can successfully treat LVOT obstruction and MR.

Systolic anterior motion of the mitral valve in hypertrophic cardiomyopathy: a narrative review

Background and Objective

The prevalence of hypertrophic cardiomyopathy (HCM) is estimated to be 1 in 200 to 500 individuals, with systolic anterior motion (SAM) of the mitral valve (MV) and left ventricular outflow tract (LVOT) obstruction present in 60% to 70%. In this narrative review, we aim to elucidate the pathophysiology of SAM-septal contact and LVOT obstruction in HCM by presenting a detailed review on the anatomy of the MV apparatus in HCM, examining the various existing theories pertaining to the SAM phenomenon as supported by cardiac imaging, and providing a critical assessment of management strategies for SAM in HCM.

Methods

A literature review was performed using PubMed, EMBASE, Ovid, and the Cochrane Library, of all scientific articles published through December 2021. A focus was placed on descriptive studies, reports correlating echocardiographic findings with pathologic diagnosis, and outcomes studies.

Key Content and Findings

The pathophysiology of SAM involves the complex interplay between HCM morphology, MV apparatus anatomic abnormalities, and labile hemodynamic derangements. Echocardiography and cardiac magnetic resonance (CMR) vector flow mapping have identified drag forces, as opposed to the "Venturi effect", as the main hydraulic forces responsible for SAM. The degree of mitral regurgitation with SAM is variable, and its severity is correlated with degree of LVOT obstruction and outcomes. First line therapy for the amelioration of SAM and LVOT obstruction is medical therapy with beta-blockers, non-dihydropyridine calcium-channel blockers, and disopyramide, in conjunction with lifestyle modifications. In refractory cases septal reduction therapy is performed, which may be combined with a 'resect-plicate-release' procedure, anterior mitral leaflet extension, surgical edge-to-edge MV repair, anterior mitral leaflet retention plasty, or secondary chordal cutting.

Conclusions

Recent scientific advances in the field of HCM have allowed for a maturation of our understanding of the SAM phenomenon. Cardiac imaging plays a critical role in its diagnosis, treatment, and surveillance, and in our ability to apply the appropriate therapeutic regimens. The increasing prevalence of HCM places an emphasis on continued basic and clinical research to further improve outcomes for this challenging population.

Recommendations for Multimodality Cardiovascular Imaging of Patients with Hypertrophic Cardiomyopathy: An Update from the American Society of Echocardiography, in Collaboration with the American Society of Nuclear Cardiology, the Society for Cardiovascular Magnetic Resonance, and the Society of Cardiovascular Computed Tomography

Hypertrophic cardiomyopathy (HCM) is defined by the presence of left ventricular hypertrophy in the absence of other potentially causative cardiac, systemic, syndromic, or metabolic diseases. Symptoms can be related to a range of pathophysiologic mechanisms including left ventricular outflow tract obstruction with or without significant mitral regurgitation, diastolic dysfunction with heart failure with preserved and heart failure with reduced ejection fraction, autonomic dysfunction, ischemia, and arrhythmias. Appropriate understanding and utilization of multimodality imaging is fundamental to accurate diagnosis as well as longitudinal care of patients with HCM. Resting and stress imaging provide comprehensive and complementary information to help clarify mechanism(s) responsible for symptoms such that appropriate and timely treatment strategies may be implemented. Advanced imaging is relied upon to guide certain treatment options including septal reduction therapy and mitral valve repair. Using both clinical and imaging parameters, enhanced algorithms for sudden cardiac death risk stratification facilitate selection of HCM patients most likely to benefit from implantable cardioverter-defibrillators.

Image-Based Computational Hemodynamics Analysis of Systolic Obstruction in Hypertrophic Cardiomyopathy

Hypertrophic Cardiomyopathy (HCM) is a pathological condition characterized by an abnormal thickening of the myocardium. When affecting the medio-basal portion of the septum, it is named Hypertrophic Obstructive Cardiomyopathy (HOCM) because it induces a flow obstruction in the left ventricular outflow tract. In any type of HCM, the myocardial function can become compromised, possibly resulting in cardiac death. In this study, we investigated with computational analysis the hemodynamics of patients with different types of HCM. The aim was quantifying the effects of this pathology on the intraventricular blood flow and pressure gradients, and providing information potentially useful to guide the indication and the modality of the surgical treatment (septal myectomy). We employed an image-based computational approach, integrating fluid dynamics simulations with geometric and functional data, reconstructed from standard cardiac cine-MRI acquisitions. We showed that with our approach we can better understand the patho-physiological behavior of intraventricular blood flow dynamics due to the abnormal morphological and functional aspect of the left ventricle. The main results of our investigation are: (a) a detailed patient-specific analysis of the blood velocity, pressure and stress distribution associated to HCM; (b) a computation-based classification of patients affected by HCM that can complement the current clinical guidelines for the diagnosis and treatment of HOCM.

Mitral annular calcification in hypertrophic cardiomyopathy

BACKGROUND

Changes in mitral valve anatomy contribute to left ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy (HCM). Mitral annular calcification (MAC) is common among patients with HCM but its implications are currently unknown.

METHODS

We tested the hypothesis that echocardiographic MAC would be associated with anterior displacement of the mitral valve and LVOTO in a cohort of 304 patients with HCM aged ≥ 60 years (mean [SD] age 71.6 [7.7] years, 52% women).

RESULTS

MAC was present in 141 (46%) patients. The mean (SD) MAC offset distance was 9.8 (4.8) mm. A higher proportion of those with MAC compared to those without MAC had SAM (84.2 vs. 63.8%, p < 0.001) and LVOTO (80.9 vs. 57.9%, p < 0.001). In patients with MAC, the septal-mitral valve distance was shorter compared to those without (19.4 [4.0] vs 21.5 [4.9] mm, p < 0.001). The mitral valve position ratio was greater in those with MAC compared to those without (1.00 [0.79, 1.22] vs. 0.86 [0.67, 1.05], p < 0.001) denoting greater anterior displacement, especially in those with MAC and LVOTO. After multivariable adjustment, MAC offset distance was associated with LVOTO (OR 1.16 [95% CI 1.07, 1.28] per mm, p = 0.001). Over a median follow-up of 2.7 years, 42 (29.8%) patients with MAC underwent surgery to relieve LVOTO, with no deaths.

CONCLUSION

This study adds MAC to the known geometrical alterations of the mitral valve that predispose to LVOTO and suggests that surgical relief of LVOTO in the presence of MAC is safe when performed by an experienced surgeon.

Left ventricular basal muscle bundle in hypertrophic cardiomyopathy: insights into the mechanism of left ventricular outflow tract obstruction

AIMS 

Many factors cause left ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy (HCM). Previous studies reported that left ventricular basal muscle bundle (BMB) may be associated with LVOTO. We aimed to evaluate the role of BMB in LVOTO by echocardiography.

METHODS AND RESULTS 

Two hundred fifty-six patients diagnosed with HCM were recruited. The morphologic characteristics of left ventricular outflow tract (LVOT) were analysed. BMB was detected in 178 (69.5%) patients by echocardiography. Patients were separated by a resting or provocative LVOT gradient ≥30 mmHg or not. Compared to patients without LVOTO, patients with LVOTO had a significantly thicker basal septum, elongated anterior mitral leaflet (AML), shorter distance between the AML-free margin and the septum or BMB (M-sept/bundle), larger angle between the plane of the mitral valvular orifice and the ascending aorta (MV-AO angle), and higher prevalence of BMB (P < 0.05). According to multivariate analysis, the independent predictors of LVOTO were the presence of BMB, a large basal septum thickness, a short M-sept/bundle, a large MV-AO angle, and a large AML [odds ratio (95% confidence interval): 5.207 (1.381-19.633), 1.386(1.141-1.683), 0.615(0.499-0.756), 1.113(1.054-1.176), and 1.343(1.076-1.677), respectively, P < 0.05]. Of the 256 included patients, 139 underwent surgical myectomy. The transthoracic echocardiography, compared with surgical specimen, showed: sensitivity 98.3%, specificity 82.3%, positive predictive value 97.6%, negative predictive value 87.5%, and accuracy 96.4% to detect BMB.

CONCLUSIONS

BMB is common in HCM. BMB is a risk factor for LVOTO.

Comprehensive left ventricular outflow tract management beyond septal reduction to relieve obstruction

The surgical management of patients with hypertrophic obstructive cardiomyopathy can be extremely challenging. Relieving the left ventricular outflow tract obstruction in these patients is often achieved by performing a septal myectomy. However, in many instances, septal reduction alone is not enough to relieve the obstruction. Interventions on the sub-valvular apparatus, including the anomalous chordae tendineae and the abnormal papillary muscles, are often required. In this review, we summarize the embryology and the pathophysiology of the different elements that may contribute to the left ventricular outflow tract obstruction in the setting of hypertrophic obstructive cardiomyopathy. In addition, we highlight the different surgical procedures that a surgeon may adopt to relieve the left ventricular outflow tract obstruction, beyond the septal myectomy.

Surgery for Hypertrophic Obstructive Cardiomyopathy: Comprehensive LVOT Management beyond Septal Myectomy

Hypertrophic cardiomyopathy (HCM) is a complex, underestimated, multifaceted disease frequently associated with left ventricular outflow tract (LVOT) obstruction. It is clearly demonstrated that this is due not only to septal hypertrophy but also to systolic anterior motion (SAM) of mitral valve leaflets secondary to mitral valve/subvalvular apparatus abnormalities. Surgical treatment involves performing an extended septal myectomy, eventually followed by ancillary procedures to those structures responsible for maintaining LVOT obstruction, if necessary. In this review, we describe the spectrum of possible surgical techniques beyond septal myectomy and their pathophysiologic rationale.

Three-Dimensional Imaging and Dynamic Modeling of Systolic Anterior Motion of the Mitral Valve

Left ventricular outflow tract (LVOT) obstruction in hypertrophic cardiomyopathy (HCM) is often caused by systolic anterior motion (SAM) of the mitral valve caused by the interplay between increased left ventricular (LV) wall thickness and an abnormal mitral valve anatomy and geometry. Three-dimensional (3D) echocardiographic imaging of the mitral valve has revolutionized the practice of cardiology, paving the way for new methods to see and treat valvular heart disease. Here we present the novel and incremental value of 3D transesophageal echocardiography (TEE) of SAM visualization. This review first provides step-by-step instructions on acquiring and optimizing 3D TEE imaging of SAM. It then describes the unique and novel findings using standard 3D TEE rendering as well as dynamic mitral valve modeling of SAM from 3D data sets, which can provide a more detailed visualization of SAM features. The findings include double-orifice LVOT caused by the residual leaflet, the dolphin smile phenomenon, and delineation of SAM width. Finally, the review discusses the essential role of 3D TEE imaging for preprocedural assessment and intraprocedural guidance of surgical and novel percutaneous treatments of SAM.

Accessory mitral valve tissue: anatomical and clinical perspectives

Mitral valve is a complex cardiac structure composed of several components to work in synchrony to allow blood flow into left ventricle during diastole and not to allow blood flow into left atrium during systole. Accessory mitral valve tissue (AMVT) was defined as existence of any additional part and parcel of valvular structure which has an attachment to normal mitral valve apparatus in left-sided cardiac chambers. AMVT may present itself in different clinical circumstances ranging from a silent clinical course to thromboembolic events, heart failure, left ventricular outflow tract obstruction, and severe arrhythmia. This article reviews the clinical perspectives of AMVT in terms of symptoms, diagnosis, and treatment, providing a new anatomical classification regarding the location of AMVT. Briefly type I refers to AMVT having attachments on the supra leaflets level, type II refers to attachments on the mitral leaflets, and type III refers to attachment below the mitral leaflets. Increased awareness and widespread use of echocardiographic techniques would increase recognition of AMVT in patients with heart murmurs but otherwise healthy and in those with left ventricular outflow tract obstruction or tissue which causes subaortic stenosis and with unexplained cerebrovascular events.

The Mitral Coaptation to Ventricular Septal Space: Two- and Three-Dimensional Transesophageal Echocardiographic Assessment

OBJECTIVES

To assess the dimensions and changes in the CSEPT (space between the ventricular septum and mitral coaptation point) before and after cardiopulmonary bypass (CPB) and to compare patients with and without aortic valve stenosis (AS) undergoing cardiac surgery.

DESIGN

Retrospective review of intraoperative transesophageal echocardiographic examinations.

SETTING

Single academic medical center.

PARTICIPANTS

The study comprised 91 elective cardiac surgical patients-30 with AS scheduled for aortic valve replacement and 61 without AS (non-AS).

INTERVENTIONS

Two- and 3-dimensional (2D and 3D) analysis of the CSEPT before and after CPB.

MEASUREMENTS AND MAIN RESULTS

Assessment of the CSEPT distances and areas was performed using 2D and 3D imaging before and after CPB. Two-dimensional measures of CSEPT distances were performed using midesophageal 5-chamber and long-axis windows. Three-dimensional measures were performed offline using multiplanar reconstruction. The CSEPT space was smaller after CPB (p < 0.01). Before and after CPB, the midesophageal 5-chamber and long-axis windows were similar to each other, and both were larger than the pre-CPB 3D CSEPT distance. Patients with AS had smaller before and after CPB distances and areas compared with non-AS patients (p < 0.05). The change in CSEPT area in AS patients was 24%.

CONCLUSIONS

The CSEPT space is smaller after CPB and more so for patients with AS undergoing aortic valve replacement. Two-dimensional CEPT distances vary compared with 3D CSEPT distances. Additional study using Doppler analysis will elucidate the added value of 3D assessment of the CSEPT space.

An image-based computational hemodynamics study of the Systolic Anterior Motion of the mitral valve

Systolic Anterior Motion (SAM) of the mitral valve - often associated with Hypertrophic Obstructive Cardiomyopathy (HOCM) - is a cardiac pathology in which a functional subaortic stenosis is induced during systole by the mitral leaflets partially obstructing the outflow tract of the left ventricle. Its assessment by diagnostic tests is often difficult, possibly underestimating its severity and thus increasing the risk of heart failure. In this paper, we propose a new computational pipeline, based on cardiac cine Magnetic Resonance Imaging (cine-MRI) data, for the assessment of SAM. The pipeline encompasses image processing of the left ventricle and the mitral valve, and numerical investigation of cardiac hemodynamics by means of Computational Fluid Dynamics (CFD) in a moving domain with image-based prescribed displacement. Patient-specific geometry and motion of the left ventricle are considered in view of an Arbitrary Lagrangian-Eulerian approach for CFD, while the reconstructed mitral valve is immersed in the computational domain by means of a resistive method. We assess clinically relevant flow and pressure indicators in a parametric study for different degrees of SAM severity, in order to provide a better quantitative evaluation of the pathological condition. Moreover, we provide specific indications for its possible surgical treatment, i.e. septal myectomy.

The Role of Mitral Valve in Hypertrophic Obstructive Cardiomyopathy: An Updated Review

Hypertrophic cardiomyopathy (HCM) is the most common inherited heart disease and the most common cause of sudden cardiac death in young population, especially in athletes under 35 years old. Mutations occur primarily in the β-myosin heavy chain gene and involve the cardiac myosin-binding protein C gene. In this review we would like to focus on the importance of the examination of mitral valve apparatus and the mitral valve abnormalities in patients with HCM. Abnormalities in mitral valve (elongated mitral leaflets, displacement of papillary muscles, and systolic anterior motion) may be the primary pathognomonic elements, even in the absence of hypertrophy. Echocardiography is the gold standard for the diagnosis of HCM. Magnetic resonance imaging emerges as one of the most important imaging modalities for precise diagnosis, assisting in risk stratification and treatment strategy. Mitral valve abnormalities take part fundamentally in the formation of systolic anterior motion of the mitral valve and, they have substantially been repaired surgically. Although myectomy addresses the septum reduction, obstruction relief should be maximally achieved with a potential combination of myectomy and mitral valve repair.

Distinctive Hypertrophic Cardiomyopathy Anatomy and Obstructive Physiology in Patients Admitted With Takotsubo Syndrome

Clinical spectrum of hypertrophic cardiomyopathy (HC) has been expanded to include patients with mild or no thickening of the left ventricle (LV), who nevertheless have outflow tract obstruction at rest or after exercise, due to systolic anterior motion (SAM) and ventricular septal contact, with mitral valve elongation and papillary muscles anomalies. Apical ballooning mimicking a takotsubo syndrome (TS) wall motion pattern can occur in HC with mild septal thickening when latent obstruction becomes unrelenting. To define the prevalence of anatomic abnormalities characteristic of HC in patients diagnosed with TS, we analyzed echocardiograms of 44 unselected TS patients, age 67±12 years, 95% women including studies performed before the event (n = 11, median 515 days) and after recovery of left ventricular function (n = 33, median 92 days, interquartile range = 29 to 327) and compared the findings to 60 age and sexed matched controls. Analysis of echocardiograms was blinded to event timing, and patient vs. control status. During the ballooning event, 13 patients (30%) had SAM including 9 with LV outflow obstruction, peak gradients 71±40 mmHg, as well as: ventricular septal thickening (16 ± 4 mm), elongated anterior leaflets (30 ± 3mm), and increased mitral coaptation to posterior wall distance (17 ± 5 mm), consistent with diagnosis of the HC phenotype. Compared to 31 TS patients without SAM, study patients with SAM had longer anterior leaflets (30 ± 3 vs 26 ± 4 mm, p = 0.006), thicker septum (16 ± 4 vs 12 ± 3 mm), increased coaptation to posterior wall distance (17 ± 5 vs 14 ± 4 mm, p < 0.04) and reduced distance from coaptation to septum (19 ± 5 vs 27 ± 5, p < 0.001). In the 13 patients with SAM, morphologic characteristics of HC persisted after normalization of LV function. In conclusion, a subset of patients experiencing TS events demonstrates a constellation of morphologic abnormalities characteristic of HC that persist after recovery of LV wall motion. These findings suggest that dynamic outflow obstruction may cause apical ballooning in susceptible patients.

Markers of responsiveness to disopyramide in patients with hypertrophic cardiomyopathy

BACKGROUND

Significant left-ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy (HCM) may result in symptoms and is associated with adverse outcomes. Although disopyramide can reduce resting gradients, nearly 30% of HCM patients do not respond. We sought to study the clinical and echocardiographic variables associated with disopyramide-induced LVOT-gradient reduction.

METHODS

Forty-one disopyramide-treated HCM patients (average daily-dose 305 mg) were subdivided into two groups: (1) nineteen responders, with a reduction of LVOT-gradients of at least 30% from baseline, and (2) twenty-two non-responders, in whom LVOT-gradients did not change or increased following treatment. All patients had a thorough clinical and echocardiographic assessment pre- and post-treatment initiation.

RESULTS

Patients who responded to disopyramide had better pretreatment left ventricular (LV) systolic function (LV ejection fraction of 67.9 ± 5.6% vs. 59.7 ± 5.8%, p = 0.0001), better LV global longitudinal strain (-17.9 ± 2.3% vs. -16.1 ± 2.5%, p = 0.048), less mitral regurgitation, smaller LV size (indexed LV end-systolic volume of 16.2 ± 5.1 ml/m² vs. 23.2 ± 6.8 ml/m², p = 0.001), and lower LV maximal wall thickness (17.2±3 mm vs.19.2 ± 3.4 mm, p = 0.046). Baseline left atrial (LA) volumes were significantly lower in the responders, with higher indices of LA ejection fraction (62 ± 11.2% vs. 50.5 ± 12.2%, p = 0.005), systolic LA strain (34 ± 12.4% vs. 25.8 ± 10.6%, p = 0.04), and LA strain-rate (1.34 ± 0.49%/sec vs. 0.99 ± 0.24%/sec, p = 0.012). In multivariable analysis, the presence of reduced LV systolic function and systolic LA strain-rate remained independently associated with poor response to disopyramide.

CONCLUSIONS

Obstructive HCM patients with more severe disease at baseline tend to respond less to disopyramide treatment. In those patients, early referral for alcohol septal ablation or myectomy surgery should be considered.

Numerical simulation study on systolic anterior motion of the mitral valve in hypertrophic obstructive cardiomyopathy

BACKGROUND

The hydrodynamic mechanisms of systolic anterior motion (SAM) of the mitral valve in hypertrophic obstructive cardiomyopathy (HOCM) remain unclear.

METHODS

Based on computed tomography (CT) images and clinical data, pre- and post-operative computational models of the left ventricle were constructed for 6 HOCM patients receiving septal myectomy. SAM was abolished in 5 patients and persisted in one after septal myectomy surgery. The obtained simulation results including flow field of the left ventricle and mechanical behaviors of the mitral valve (MV) between pre- and post-operative FSI models were compared.

RESULTS

The pressure difference and shear stress on the mitral valve leaflets (MVL) were relatively high pre-operatively, and decreased significantly after satisfactory surgery, but remained high following failed surgery. The significant increase in coaptation-to-septal distance was found when SAM was abolished.

CONCLUSIONS

Our results indicated that high pressure difference and shear stress on the MVL might directly initiate SAM in HOCM. Successful septal myectomy enlarged the coaptation-to-septal distance sufficiently to keep the MVL away from the ejection flow, thereby eliminating SAM.

Hypertrophic cardiomyopathy with dynamic obstruction and high left ventricular outflow gradients associated with paradoxical apical ballooning

BACKGROUND

Acute left ventricular (LV) apical ballooning with normal coronary angiography occurs rarely in obstructive hypertrophic cardiomyopathy (OHCM); it may be associated with severe hemodynamic instability.

METHODS, RESULTS

We searched for acute LV ballooning with apical hypokinesia/akinesia in databases of two HCM treatment programs. Diagnosis of OHCM was made by conventional criteria of LV hypertrophy in the absence of a clinical cause for hypertrophy and mitral-septal contact. Among 1519 patients, we observed acute LV ballooning in 13 (0.9%), associated with dynamic left ventricular outflow tract (LVOT) obstruction and high gradients, 92 ± 37 mm Hg, 10 female (77%), age 64 ± 7 years, LVEF 31.6 ± 10%. Septal hypertrophy was mild compared to that of the rest of our HCM cohort, 15 vs 20 mm (P < 0.00001). An elongated anterior mitral leaflet or anteriorly displaced papillary muscles occurred in 77%. Course was complicated by cardiogenic shock and heart failure in 5, and refractory heart failure in 1. High-dose beta-blockade was the mainstay of therapy. Three patients required urgent surgical relief of LVOT obstruction, 2 for refractory cardiogenic shock, and one for refractory heart failure. In the three patients, surgery immediately normalized refractory severe LV dysfunction, and immediately reversed cardiogenic shock and heart failure. All have normal LV systolic function at 45-month follow-up, and all have survived.

CONCLUSIONS

Acute LV apical ballooning, associated with high dynamic LVOT gradients, may punctuate the course of obstructive HCM. The syndrome is important to recognize on echocardiography because it may be associated with profound reversible LV decompensation.

Phenotypes of hypertrophic cardiomyopathy. An illustrative review of MRI findings

Objective

The purpose of this article is to review how cardiac MRI provides the clinician with detailed information about the hypertrophic cardiomyopathy (HCM) phenotypes, assessing its morphological and functional consequences.

Conclusion

An understanding of cardiac MRI manifestations of HCM phenotypes will aid early diagnosis recognition and its functional consequences.

Teaching Points

• The phenotypic variability of HCM expands beyond myocardial hypertrophy, to include morphological and functional manifestations, ranging from subtle anomalies to remodelling of the LV with progressive dilatation and thinning of its wall.

• The stages of HCM, which are based on the clinical evidence of disease progression, include subclinical HCM, the classic HCM phenothype, adverse remodelling and overt dysfunction, or end-stage HCM.

• Cardiac MRI provides the clinician with detailed information regarding the HCM phenotypes and enables the assessment of its functional consequences.

Intrinsic mitral valve alterations in hypertrophic cardiomyopathy sarcomere mutation carriers

Aims

Mitral valve (MV) abnormalities are recognized features of hypertrophic cardiomyopathy (HCM), and there is preliminary evidence suggesting they are intrinsic phenotypic manifestations of sarcomere mutations, present in mutation carriers without left ventricular (LV) hypertrophy (subclinical HCM). However, further study is required to characterize the nature of these changes and their functional impact. Thus, we performed comprehensive echocardiographic analysis of MV structure and function on a genotyped population.

Methods and results

MV and papillary muscle echocardiographic parameters were measured in 192 genotyped individuals, including 50 overt HCM, 79 subclinical HCM, and 63 mutation-negative, healthy relatives as normal controls. Compared to controls, subclinical HCM subjects had elongated anterior MV leaflets relative to LV end-diastolic volume index (0.57 ± 0.02 vs. 0.51 ± 0.02 mm/mL/m2, P = 0.013) and anteriorly displaced papillary muscles [decreased papillary-septal separation (31.1 ± 0.7 vs. 34.2 ± 0.9 mm, P = 0.004) and relative antero-posterior position ratio of the papillary muscles (0.67 ± 0.01 vs. 0.71 ± 0.01, P = 0.011]. Similar findings were identified comparing overt HCM to controls. These MV changes were associated with an increased prevalence of systolic anterior motion (SAM) of the MV amongst subclinical HCM subjects.

Conclusions

Sarcomere mutations are associated with primary abnormalities of the MV apparatus, specifically excess anterior leaflet length relative to LV cavity size and anterior displacement of the papillary muscles; both features predisposing to SAM. These abnormalities appear to be early phenotypic consequences of sarcomere mutations, observed in mutation carriers with normal LV wall thickness.

Management of systolic anterior motion of the mitral valve: a mechanism-based approach

Although the mechanism of systolic anterior motion (SAM) of the mitral valve is unknown, it is known to have a multifactorial pathophysiology. Echocardiographic analysis of the mitral leaflet revealed the step-wise progression of SAM, and intraventricular flow analysis revealed the contribution of drag force generated by the misled flow below the posterior leaflet. Although several diverse clinical features of SAM are already known, some key features need to be abstracted from among them to understand the regulation of SAM establishment. This paper reviews past articles that have investigated the mechanism of SAM and proposes a mechanism-based concept to provide insights for better comprehension of SAM recognition.