2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy: A Report of the American Heart Association/American College of Cardiology Joint Committee on Clinical Practice Guidelines.

AIM: The "2024 AHA/ACC/AMSSM/HRS/PACES/SCMR Guideline for the Management of Hypertrophic Cardiomyopathy" provides recommendations to guide clinicians in the management of patients with hypertrophic cardiomyopathy. METHODS: A comprehensive literature search was conducted from September 14, 2022, to November 22, 2022, encompassing studies, reviews, and other evidence on human subjects that were published in English from PubMed, EMBASE, the Cochrane Library, the Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Additional relevant studies, published through May 23, 2023, during the guideline writing process, were also considered by the writing committee and added to the evidence tables, where appropriate. STRUCTURE: Hypertrophic cardiomyopathy remains a common genetic heart disease reported in populations globally. Recommendations from the "2020 AHA/ACC Guideline for the Diagnosis and Treatment of Patients With Hypertrophic Cardiomyopathy" have been updated with new evidence to guide clinicians.

Mitral Regurgitation and Left Ventricular Outflow Tract Obstruction: Confluence of Challenges for Transcatheter Treatment.

The intricate interplay between mitral regurgitation (MR) and left ventricular outflow tract (LVOT) obstruction may result in two clinical scenarios: prosthesis-related LVOT obstruction after mitral valve replacement (TMVR) and systolic anterior motion (SAM)-associated MR. This review provides a comprehensive overview of the pathophysiology, risk assessment, and transcatheter interventions for mitigating the likelihood of LVOT obstruction in patients undergoing TMVR. In addition, it extends its focus to SAM-associated MR, elucidating the different aetiological mechanisms contributing to this phenomenon, beyond hypertrophic cardiomyopathy. Transcatheter treatment options, are explored as potential therapeutic strategies, offering insights into their hemodynamic effectiveness and limitations.

The role of point-of-care ultrasound to monitor response of fluid replacement therapy in pregnancy.

Fluid management in obstetrical care is crucial because of the complex physiological conditions of pregnancy, which complicate clinical manifestations and fluid balance management. This expert review examined the use of point-of-care ultrasound to evaluate and monitor the response to fluid therapy in pregnant patients. Pregnancy induces substantial physiological changes, including increased cardiac output and glomerular filtration rate, decreased systemic vascular resistance, and decreased plasma oncotic pressure. Conditions, such as preeclampsia, further complicate fluid management because of decreased intravascular volume and increased capillary permeability. Traditional methods for assessing fluid volume status, such as physical examination and invasive monitoring, are often unreliable or inappropriate. Point-of-care ultrasound provides a noninvasive, rapid, and reliable means to assess fluid responsiveness, which is essential for managing fluid therapy in pregnant patients. This review details the various point-of-care ultrasound modalities used to measure dynamic changes in fluid status, focusing on the evaluation of the inferior vena cava, lung ultrasound, and left ventricular outflow tract. Inferior vena cava ultrasound in spontaneously breathing patients determines diameter variability, predicts fluid responsiveness, and is feasible even late in pregnancy. Lung ultrasound is crucial for detecting early signs of pulmonary edema before clinical symptoms arise and is more accurate than traditional radiography. The left ventricular outflow tract velocity time integral assesses stroke volume response to fluid challenges, providing a quantifiable measure of cardiac function, which is particularly beneficial in critical care settings where rapid and accurate fluid management is essential. This expert review synthesizes current evidence and practice guidelines, suggesting the integration of point-of-care ultrasound as a fundamental aspect of fluid management in obstetrics. It calls for ongoing research to enhance techniques and validate their use in broader clinical settings, aiming to improve outcomes for pregnant patients and their babies by preventing complications associated with both under- and overresuscitation.

Hypertrophic Cardiomyopathy: Preadolescence, Mitral Valve Disease, and Midventricular Obstruction.

Septal myectomy is indicated in patients with obstructive hypertrophic cardiomyopathy (HCM) who have persistent symptoms despite medical therapy, intolerance of medication side effects, or severe resting or provocable gradients. Septal myectomy at high volume centers is safe, with low operative mortality (1%) and low rates of complications such as complete heart block or ventricular septal defect (3% and 0.5%, respectively). Additionally, improved survival following myectomy has been observed when compared to patients with obstructive HCM managed medically or those with nonobstructive HCM. As a longstanding, quaternary referral center for septal myectomy, our institution has built significant experience and expertise in the surgical and medical management of HCM, including atypical HCM, defined as preadolescent patients, those with mitral valve disease, and those with isolated midventricular obstruction. The most important factor of septal myectomy in achieving complete resolution of obstruction and avoiding recurrence is the apical extent of the myectomy trough, which must extend to the septum opposite the papillary muscles. If this cannot be fully achieved via a transaortic exposure, especially in preadolescents and patients with midventricular obstruction, then a transapical approach may be needed. Mitral valve repair is rarely necessary as SAM-mediated MR resolves with adequate myectomy alone, but mitral repair is performed in cases of intrinsic valvular disease. In this manuscript we provide a summary of current operative techniques and outcomes data from our institution on the management of these various categories of HCM.

Molecular Pathways and Animal Models of Hypoplastic Left Heart Syndrome.

Hypoplastic left heart syndrome (HLHS) is a severe congenital heart disease (CHD) with underdevelopment of left-sided heart structures. While previously uniformly fatal, surgical advances now provide highly effective palliation that allows most HLHS patients to survive their critical CHD. Nevertheless, there remains high morbidity and mortality with high risk of heart failure. As hemodynamic compromise from restricted aortic blood flow has been suggested to underlie the poor LV growth, this suggests the possibility of prenatal fetal intervention to recover LV growth. As such interventions have yielded ambiguous results, the optimization of therapy will require more mechanistic insights into the developmental etiology for HLHS. Clinical studies have shown high heritability for HLHS, with an oligogenic etiology indicated in conjunction with genetic heterogeneity. This is corroborated with the recent recovery of mutant mice with HLHS. With availability-induced pluripotent stem cell (iPSC)-derived cardiomyocytes from HLHS mice and patients, new insights have emerged into the cellular and molecular etiology for the LV hypoplasia in HLHS. Cell proliferation defects were observed in conjunction with metaphase arrest and the disturbance of Hippo-YAP signaling. The left-sided restriction of the ventricular hypoplasia may result from epigenetic perturbation of pathways regulating left-right patterning. These findings suggest new avenues for fetal interventions with therapies using existing drugs that target the Hippo-YAP pathway and/or modulate epigenetic regulation.

Multimodal imaging diagnosis of left ventricular outflow tract obstruction due to abnormal papillary muscle insertion.

This article reports a case of LV outflow obstruction caused by abnormalities of the anterior leaflet connection of the mitral papillary muscle, aiming to highlight the importance of combined multimodal imaging in the differential diagnosis of the etiology of LV outflow obstruction.

Is Congenital Muscular Mitral-Aortic Discontinuity Another Feature of Obstructive Hypertrophic Cardiomyopathy? A Pathology Validation Study.

Hypertrophic cardiomyopathy (HCM) is an inherited myocardial disease at risk of sudden cardiac death and heart failure, even requiring heart transplantation. A "muscular mitral-aortic discontinuity" has been reported during surgery in the obstructive form. We aimed to validate these findings through pathological analysis of HCM heart specimens from the cardiovascular pathology tissue registry. Hearts with septal asymmetric HCM from sudden cardiac death, other causes of death, or heart transplantation were included. Sex-matched and age-matched patients without HCM served as controls. Gross and histologic analysis of the mitral valve (MV) apparatus and the mitral-aortic continuity were performed. Thirty HCM hearts (median age, 29.5 years; 15 men) and 30 controls (median age, 30.5 years; 15 men) were studied. In HCM hearts, a septal bulging was present in 80%, an endocardial fibrous plaque in 63%, a thickening of the anterior MV leaflet in 56.7%, and an anomalous insertion of papillary muscle in 10%. All cases but 1 (97%) revealed a myocardial layer overlapping the mitral-aortic fibrous continuity on the posterior side, corresponding to the left atrial myocardium. A negative correlation between the length of this myocardial layer and the age and the anterior MV leaflet length was found. The length did not differ between HCM and controls. Pathologic study of obstructive HCM hearts does not confirm the existence of a "muscular mitral-aortic discontinuity". An extension of left atrial myocardium, overlapping posteriorly the intervalvular fibrosa, is rather visible, and its length decreases with age, possibly as a consequence of left atrial remodeling. Our study highlights the fundamental role of thorough gross examination and the value of organ retention for further analysis in order to validate new surgical and imaging findings.

Mitral Valve in Obstructive Hypertrophic Cardiomyopathy: Abnormalities, Management and Controversies.

Obstructive hypertrophic cardiomyopathy (obstructive HCM) is a hereditary disease characterized by septal hypertrophy and dynamic left ventricular outflow tract (LVOT) obstruction. Other than septal hypertrophy, mitral valve abnormalities are also quite common in patients with obstructive HCM, which may contribute to systolic anterior motion (SAM) of the mitral valve and LVOT obstruction. Surgical myectomy is the standard treatment to achieve anatomic correction of obstructive HCM, but controversies remain on whether and how the mitral valve procedures should be performed at the same time. In this review, we first described the mitral valve abnormalities in patients with obstructive HCM and their surgical corrections, we then explained the controversies based on current clinical studies, and we finally made a brief introduction on our surgical strategy and results.

Acute Left Ventricular Ballooning: Tools to Differentiate Hypertrophic Cardiomyopathy with Outflow Obstruction from Neurohumoral Takotsubo Syndrome.

Despite considerable interest in the syndrome of acute left ventricular (LV) ballooning, its pathophysiology has remained ill-defined. In this review, we explore observational data describing two etiologies of acute LV ballooning: neurohumoral classic Takotsubo Syndrome (TTS), and acute severe unrelenting left ventricular outflow tract (LVOT) obstruction in patients with obstructive hypertrophic cardiomyopathy (HCM). We describe the clinical presentation and varying pathophysiology of these presentations, explore how echocardiography and cardiac catheterization may help differentiate between the two etiologies, and detail differences in management. We highlight the significant overlap as well as key differentiating features of these conditions, with the aim to improve diagnostic awareness and accuracy and appropriately tailor therapy.

Preemptive alcohol septal ablation prior to transcatheter mitral valve replacement.

BACKGROUND: Alcohol septal ablation (ASA) has been shown to increase the neo-left ventricular outflow tract (LVOT) area before transcatheter mitral valve replacement (TMVR) but there is little literature on its success and use with dedicated devices. AIMS: To describe our experience with preemptive ASA to increase the predicted neo-LVOT area and its utility with both dedicated TMVR devices and balloon-expandable valves. METHODS: All patients who underwent ASA for TMVR candidacy in our center between May 2018 and October 2022 and had computed tomography (CT) scans done before and after ASA were included. Each CT was assessed for the minimum predicted neo-LVOT area at end-systole, using a virtual valve of the desired TMVR device for each patient. The primary outcome was an increase in the predicted neo-LVOT area after ASA that was deemed sufficient for safe implantation of the desired TMVR device. The secondary outcome was the absence of acute LVOT obstruction after TMVR. RESULTS: A total of 12 patients underwent ASA and all but 1 (n = 11, 91.6%) achieved the primary outcome of having sufficient predicted neo-LVOT area to proceed with TMVR. The mean increase in neo-LVOT area after ASA was 126 ± 64 mm2 (median 119.5, interquartile range: 65.0-163.5 mm2 ). Two patients (16.7%) required a permanent pacemaker after ASA. Nine patients went on and underwent TMVR with their respective devices and none had LVOT obstruction after the procedure. Among the remaining three patients, one had insufficient neo-LVOT clearance after ASA, one had unrelated mortality before TMVR, and one had advanced heart failure before TMVR. CONCLUSION: In appropriately selected patients and at centers experienced with ASA, preemptive ASA can achieve sufficient neo-LVOT clearance for TMVR with a variety of devices in approximately 90% of patients.

The Role of Focused 2-Dimensional Echocardiography in Managing Left Ventricular Outflow Tract Obstruction Mimicking Cardiogenic Shock.

Left ventricular outflow tract obstruction (LVOTO) is a common cardiogenic shock (CS) mimic. We present 3 cases of patients presenting with CS following myocardial infarction, exhibiting a poor response to conventional treatment with inotropy and mechanical circulatory support. This triggered echocardiographic assessment by critical care physicians using focused 2-dimensional (2D) echocardiography. This timely assessment identified anterior mitral valve leaflet entrainment into the left ventricular outflow tract (LVOT), causing LVOTO as the underlying shock mechanism. Echocardiographic findings have led to significant changes in management. The patients underwent fluid administration, weaning from inotropy, and mechanical circulatory support explantation, leading to relief of LVOTO and improved hemodynamics. Critical care basic 2D echocardiography accreditations focus on myocardial function and pericardial effusions. Relevant societies administering these accreditations should consider adding LVOT assessment to enable timely diagnosis of this life-threatening CS mimic.

Deep learning for automated left ventricular outflow tract diameter measurements in 2D echocardiography.

BACKGROUND: Measurement of the left ventricular outflow tract diameter (LVOTd) in echocardiography is a common source of error when used to calculate the stroke volume. The aim of this study is to assess whether a deep learning (DL) model, trained on a clinical echocardiographic dataset, can perform automatic LVOTd measurements on par with expert cardiologists. METHODS: Data consisted of 649 consecutive transthoracic echocardiographic examinations of patients with coronary artery disease admitted to a university hospital. 1304 LVOTd measurements in the parasternal long axis (PLAX) and zoomed parasternal long axis views (ZPLAX) were collected, with each patient having 1-6 measurements per examination. Data quality control was performed by an expert cardiologist, and spatial geometry data was preserved for each LVOTd measurement to convert DL predictions into metric units. A convolutional neural network based on the U-Net was used as the DL model. RESULTS: The mean absolute LVOTd error was 1.04 (95% confidence interval [CI] 0.90-1.19) mm for DL predictions on the test set. The mean relative LVOTd errors across all data subgroups ranged from 3.8 to 5.1% for the test set. Generally, the DL model had superior performance on the ZPLAX view compared to the PLAX view. DL model precision for patients with repeated LVOTd measurements had a mean coefficient of variation of 2.2 (95% CI 1.6-2.7) %, which was comparable to the clinicians for the test set. CONCLUSION: DL for automatic LVOTd measurements in PLAX and ZPLAX views is feasible when trained on a limited clinical dataset. While the DL predicted LVOTd measurements were within the expected range of clinical inter-observer variability, the robustness of the DL model requires validation on independent datasets. Future experiments using temporal information and anatomical constraints could improve valvular identification and reduce outliers, which are challenges that must be addressed before clinical utilization.

Hybrid First-stage Palliation and Other Strategies to Achieve Biventricular Repair in High-Risk Neonates With Complex Heart Anomalies and Aortic Arch Obstruction.

Medical and surgical advances have allowed single-stage total repair in neonates born with complex congenital heart anomalies and aortic arch obstruction. Nonetheless, total repair might be too complex or high risk in certain neonates with demographic, clinical or morphologic risk factors. Alternative management strategies might offer these neonates better outcomes with superior anatomic repair, shorter hospitalization, reduced morbidity, and improved survival. Alternative initial surgical strategies might include aortic arch repair and pulmonary artery band with or without cardiopulmonary bypass, extracardiac repair only and pulmonary artery band, Norwood operation, and hybrid first-stage palliation; all deferring complex biventricular intra-cardiac repair to later stage. The strategy choice should be personalized to each patient, taking into consideration the morphologic and clinical state, and the existent goals of care.

Surgical treatment of recurrent subvalvular discrete membrane and left ventricular outflow tract stenosis in an adult patient with a history of congenital cardiac surgery.

Left ventricular outflow stenosis can develop at the supravalvular, valvular, and subvalvular levels. Resection of strictures at the diffuse subvalvular level is very difficult. In such pathologies, Konno-Rastan procedure provides very successful solutions as an anterior aortoventriculoplasty method. In this article, we performed anterior aortaventriculoplasty surgical treatment for tunnel type left ventricular outflow tract stenosis, recurrent subvalvular discrete membrane, and aortic regurgitation in an adult patient with a history of partial atrioventricular septal defect repair and subvalvular discrete membrane resection operation in early childhood. The Konno-Rastan procedure, which we applied to the redo case, which is rarely used in adult patients and rarely seen in the literature, is shared.

A rare combination of Ebstein's anomaly with left ventricular outflow tract obstruction.

We describe a rare case of Ebstein's anomaly (EA) combined with left ventricular outflow tract obstruction in a 54-year-old man that was accurately identified by echocardiography, cardiac magnetic resonance imaging (CMR). The imaging result was ultimately validated by surgery. We emphasize the clinical importance of using echocardiography and CMR together to provide a thorough, noninvasive explanation of these results.

The Left Outflow Tract in Fetal Cardiac Screening Examination: Introduction of Quality Criteria Is Not Always Associated With an Improvement of Practice When Supervised by Humans.

OBJECTIVES: Since 2016, the French CNEOF included the left ventricular outflow tract (LVOT) in the second and third trimester of pregnancy in addition to the four-chamber view and the parasagittal view of the right outflow tract. The objective of this study was to define quality criteria for fetal LVOT assessment and to perform a human audit of past and current practices, before and after the implementation of those quality criteria at a large scale. METHODS: Seven quality criteria were investigated and rated from 0 to 1 during three periods of interest. Files were randomly selected from three centers, and average total and specific scores were calculated. RESULTS: LVOT pictures were present in more than 94.3% of reports. The average quality score was 5.49/7 (95% confidence interval [CI]: 5.36-5.62), 5.91/7 (95% CI: 5.80-6.03), and 5.70/7 (95% CI: 5.58-5.82) for the three centers in the three periods of interest. There was no significant difference following the introduction of the quality criteria, 2017 versus 2020, P = .054. CONCLUSION: Fetal LVOT images were present in most of ultrasound reports but the introduction of the proposed quality criteria under human supervision seems not associated with a significant change in practice.

Experience of left ventricular outflow tract arrhythmia ablation in paediatric patients using limited fluoroscopy and three-dimensional mapping technique.

OBJECTIVE: The left ventricular outflow tract is an important source of ventricular arrhythmias. Up to one-third of all idiopathic ventricular arrhythmias in patients with structurally normal hearts may arise from this region. We would like to share the results of our left ventricular outflow tract ablation using three-dimensional mapping and limited fluoroscopy. MATERIALS AND METHODS: This is a single-centre retrospective cohort study. Forty-six consecutive patients who underwent left ventricular outflow tract ablation procedures between January 2015 and June 2023 were included in the study. The EnSite Precision System (Abbott, St. Paul, MN, USA) was used to facilitate mapping and to reduce or eliminate the need for fluoroscopy. RESULTS: The study group comprised 29 males and 17 females, with a mean age of 13.4 ± 4.5 years. The most common location for arrhythmias was the left coronary cusp (n : 21). Other locations, in sequence, included the junction of the right and left coronary commissure (n : 10), right coronary cusp (n : 10), left ventricular outflow tract endocardium (n:4), aorto-mitral junction (n : 1), and great cardiac vein (n : 1). Nine of these patients had previously undergone unsuccessful right ventricular outflow tract ablation at another centre. Cryoablation was performed in three patients, irrigated radiofrequency ablation in three patients, and conventional radiofrequency ablation in the remaining patients. The acute success rate was 100%, and no recurrences were observed. The mean follow-up period was 49.6 ± 24.4 months. All patients were asymptomatic and were being followed without antiarrhythmic medication. CONCLUSION: Although left ventricular outflow tract ablations pose a risk for coronary artery and heart valve complications, they can be performed successfully and safely with the guidance of three-dimensional mapping.

Surgical strategies to address re-operative complex left ventricular outflow tract and thoracic aortic pathology: Cleveland Clinic children's experience.

BACKGROUND: Complex patients requiring operations on the left ventricular outflow tract, aortic valve, or thoracic aorta after previous repair of aortopathy constitute a challenging group, with limited information guiding decision-making. We aimed to use our institutional experience to highlight management challenges and describe surgical pearls to address them. METHODS: Forty-one complex patients with surgery on the left ventricular outflow tract, aortic valve, or aorta at Cleveland Clinic Children's between 2016 and 2021 following previous repair of aortic pathology were retrospectively reviewed. Patients with known connective tissue disease or single ventricle circulation were excluded. RESULTS: Median age at index procedure was 23 years (range 0.25-48) with median of 2 prior sternotomies. Previous aortic operations included subvalvular (n = 9), valvular (n = 6), supravalvular (n = 13), and multi-level surgeries (n = 13). Four deaths occurred in median follow-up of 2.5 years. Mean left ventricular outflow tract gradients improved significantly for patients with obstruction (34.9 ± 17.5 mmHg versus 12.6 ± 6.0 mmHg; p < 0.001). Technical pearls include the following: 1) liberal use of anterior aortoventriculoplasty with valve replacement; 2) primarily anterior aortoventriculoplasty following the subpulmonary conus in contrast to more vertical incision for post-arterial switch operation patients; 3) pre-operative imaging of mediastinum and peripheral vasculature for cannulation and sternal re-entry; and 4) proactive use of multi-site peripheral cannulation. CONCLUSIONS: Operation to address the left ventricular outflow tract, aortic valve, or aorta following prior congenital aortic repair can be accomplished with excellent outcomes despite high complexity. These procedures commonly include multiple components, including concomitant valve interventions. Cannulation strategies and anterior aortoventriculoplasty in specific patients require modifications.

Systolic anterior motion of a transatrial transcatheter mitral valve replacement causing left ventricular outflow tract obstruction.

Transatrial transcatheter mitral valve replacement is a hybrid strategy involving placing the patient on cardiopulmonary bypass and direct implantation of a transcatheter valve in a calcified annulus for mitral annular calcification. We report a rare phenomenon of systolic anterior motion of the leaflets of a transcatheter heart valve prosthesis used for mitral valve replacement causing left ventricular outflow tract obstruction. Although reported in transcatheter mitral valve replacement, we believe this is the first report of left ventricular outflow tract obstruction after transatrial mitral valve replacement and discuss the pre-disposing risk factors.

[Mitral valve replacement in patients with obstructive hypertrophic cardiomyopathy]. / Protezirovanie mitral'nogo klapana u bol'nykh obstruktivnoi gipertroficheskoi kardiomiopatiei.

OBJECTIVE: To analyze the incidence and causes of mitral valve replacement in patients with obstructive hypertrophic cardiomyopathy (HCM). MATERIAL AND METHODS: There were 172 patients (98 women and 74 men) with obstructive HCM and severe mitral valve insufficiency between November 2017 and May 2023. All patients complained of chronic heart failure NYHA class III. Surgical correction of left ventricular outflow tract (LVOT) obstruction and mitral valve repair with elimination of systolic anterior motion were technically successful in 160 (93.0%) patients. RESULTS: The need for mitral valve replacement was noted in 12 (7.0%) patients. Mean cardiopulmonary bypass time was 83.5±19.2 min (94; 127), aortic cross-clamping - 62.8±14.3 min (70; 102). In 5 cases, primary mitral valve replacement was scheduled due to obvious organic lesion of the mitral valve (tearing of chords, rheumatic lesion with leaflet restriction). In 7 patients, valve replacement was forced after ineffective primary septal myectomy (LVOT pressure gradient, severe mitral insufficiency). CONCLUSION: Mitral valve replacement is an involuntary strategy after ineffective myectomy with severe mitral insufficiency and high LVOT pressure gradient.