Degree Of Left Ventricular Outflow Tract Obstruction Research Articles

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

Background and ObjectiveThe 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.MethodsA 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 FindingsThe 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.ConclusionsRecent 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.

4D flow MRI left atrial kinetic energy in hypertrophic cardiomyopathy is associated with mitral regurgitation and left ventricular outflow tract obstruction.

To noninvasively assess left atrial (LA) kinetic energy (KE) in hypertrophic cardiomyopathy (HCM) patients using 4D flow MRI and evaluate coupling associations with mitral regurgitation (MR) and left ventricular outflow tract (LVOT) obstruction. Twenty-nine retrospectively identified patients with HCM underwent 4D flow MRI. MRI-estimated peak LVOT pressure gradient (∆PMRI) was used to classify patients into non-obstructive and obstructive HCM. Time-resolved volumetric LA kinetic energy (KELA) was computed throughout systole. Average systolic (KELA-avg) and peak systolic (KELA-peak) KELA were compared between non-obstructive and obstructive HCM groups, and associations to MR severity and LVOT ∆PMRI were tested.The study included 15 patients with non-obstructive HCM (58.6 [45.9, 65.2] years, 7 females) and 14 patients with obstructive HCM (51.9 [47.6, 62.6] years, 6 females). Obstructive HCM patients demonstrated significantly elevated instantaneous KELA over all systolic time-points compared to non-obstructive HCM (P < 0.05). Obstructive HCM patients also demonstrated higher KELA-avg (14.8 [10.6, 20.4] J/m3 vs. 33.4 [23.9, 61.3] J/m3, P < 0.001) and KELA-peak (22.1 [15.9, 28.7] J/m3 vs. 57.2 [44.5, 121.4] J/m3, P < 0.001) than non-obstructive HCM. MR severity was significantly correlated with KELA-avg (rho = 0.81, P < 0.001) and KELA-peak (rho = 0.79, P < 0.001). LVOT ∆PMRI was strongly correlated with KELA metrics in obstructive HCM (KELA-avg: rho = 0.86, P < 0.001; KELA-peak: rho = 0.85, P < 0.001).In HCM patients, left atrial kinetic energy, by 4D flow MRI, is associated with MR severity and the degree of LVOT obstruction.

Biatrial performance in children with hypertrophic cardiomyopathy: CMR study

ObjectivesTo investigate biatrial mechanics and their relation with left ventricular outflow tract (LVOT) obstruction (LVOTO), the degree of hypertrophy, indices of ventricular diastolic function and fibrosis in children with hypertrophic cardiomyopathy (HCM).MethodsFifty-five consecutive, prospectively recruited children with HCM (mean age 12.5 ± 4.6 years, 69.1% male), 19 (34.5%) of whom had LVOTO, underwent cardiac magnetic resonance and echocardiography with quantification of phasic components of biatrial function, biventricular diastolic function and fibrosis. Twenty healthy, sex-matched subjects served as controls.ResultsWe found a significant increase of left atrial (LA) and right atrial (RA) volumes and reduction in the majority of indices of contractile function, strains and strain rates (p < 0.05) in children with HCM compared with controls. Nearly all of the LA dynamics markers attained a significant association with the LVOT gradient (p < 0.05), the RA volumes and contractile functions were affected by LV fibrosis and mass (p < 0.05), and the RA mechanical components were related to the degree of LVOTO (p < 0.05). The minority of biatrial dynamics markers were associated with indices of ventricular diastolic function.ConclusionsThe majority of biatrial volumetric and functional indices were severely compromised in children with HCM compared with controls. The degree of LVOTO appears to trigger LA volumetric and LA and RA mechanical malfunction. On the other hand, the deterioration of RA volumetric components was linked to LV fibrosis and mass.Key Points• Biatrial function was severely compromised in children with HCM.• Left atrial malfunction was associated with the degree of LVOTO.• Fibrosis and LV mass were related to RA volumetric and contractile dysfunction.• The degree of LVOTO was linked to right atrial mechanical abnormalities.

Evaluation of left ventricular outflow tract obstruction with 4D phase contrast in patients with hypertrophic cardiomyopathy

Background Patients with hypertrophic cardiomyopathy (HCM) develop left ventricular outflow tract (LVOT) obstruction due to combination of asymmetric septal hypertrophy and systolic anterior motion of the mitral leaflet. Degree of LVOT obstruction is an important predictor in patient symptoms and clinical outcome. LVOT obstruction is currently assessed by Doppler echocardiography (echo) using peak velocity to calculate pressure gradient in the LVOT. 4D phase contrast (4D PC) MRI is an emerging technique for quantification of regional flow and velocity. 4D PC MRI is a 3 dimensional, 3 directionally encoded, time resolved (cine) velocity acquisition. It has the advantage of providing full 3D volume coverage and flexibility of retrospective analysis of flow at any location and in any imaging plane. In this preliminary study, we

Successful negative inotropic treatment of acute left ventricular outflow tract obstruction by elongated mitral valve leaflet

Elongated anterior mitral valve leaflet (EAMVL) has not been reported to cause left ventricular outflow tract obstruction (LVOTO) in the absence of left ventricular hypertrophy. We report the case of an elderly male patient who presented with acute heart failure and severe mitral regurgitation in the setting of dehydration. Echocardiography revealed acute LVOTO secondary to EAMVL. The patient was ineligible for surgery and was treated with negative inotropic agents, which ensured resolution of heart failure and marked improvement in the degree of LVOTO. This case demonstrates that, under certain circumstances, EAMVL without associated left ventricular hypertrophy may produce hemodynamic compromise that can be successfully treated medically.

Negative Ionotropic Agents for the Treatment of Left Ventricular Outflow Tract Obstruction Due to Sigmoid Septum and Concentric Left Ventricular Hypertrophy

Negative ionotropic agents are established treatments for left ventricular outflow tract obstruction (LVOTO) in hypertrophic cardiomyopathy (HCM). However, their benefit in those with LVOTO without typical HCM is unclear. We evaluated if negative ionotropic agents are beneficial in treatment of LVOTO in patients without typical HCM. In this retrospective cohort study, we evaluated echocardiograms and reviewed records of 15 patients with resting LVOT obstruction due to sigmoid septum (SS, n=9) and mild concentric left ventricular hypertrophy (LVH, n=6). Patients received treatment with sequential negative ionotropic agents (β-blockers and disopyramide). Initial symptoms, presentation characteristics and echocardiographic characteristics pre and post treatment were evaluated. Fifteen patients (mean age 66.2 years, 46.7% male) were included. Dyspnoea (NYHA Class II/III) was reported as the initial symptom in all patients with four patients reporting chest pain. All patients had hypercontractile LV function at baseline (fractional shortening 46.29±8.77%) but had normal LVS/PW ratio (1.03±0.10). The mean resting LVOT gradient was 74.4±55.2 mmHg. Fourteen patients received initial β-blocker therapy with a mean reduction in peak LVOT gradient of 40.9 mmHg seen in 11 patients that responded to therapy (p=0.02). Nine patients received disopyramide with a further 24.2±25.8 mmHg reduction in peak LVOT gradient observed in eight patients who tolerated treatment (p=0.04). Symptomatic improvement occurred in 80% of treated patients. In patients with LVOTO without typical HCM, sequential treatment with negative ionotropes is associated with a significant reduction in the degree of LVOTO and leads to symptomatic improvement.

Left Ventricular Outflow Tract Gradient Variability in Hypertrophic Cardiomyopathy

The presence and magnitude of left ventricular outflow tract (LVOT) obstruction directs the management algorithm in symptomatic patients with hypertrophic cardiomyopathy (HCM). Although it is well known that the degree of LVOT obstruction is dynamic and dependent upon ventricular load and contractility, the magnitude and potential impact of the day-to-day variability seen in practice has not been well appreciated. We hypothesized that LVOT gradient variability in HCM has an impact on clinical decision-making. A total of 100 HCM patients (mean age, 58 +/- 13 years; 47% male) underwent comprehensive 2-dimensional Doppler transthoracic echocardiography and cardiac catheterization with transseptal measurement of left-sided pressures. All studies were performed within 48 hours of one another. The correlation of LVOT gradients from both methods performed at different times had a wide scatter with the 95% confidence limits of agreement being +/- 84 mm Hg. For classifying patients as having severe LVOT obstruction on the basis of either method (<30 vs > or = 30 mm Hg), discrepant results occurred in 21% of patients. To confirm the accuracy of Doppler measurements, 15 studies were performed with simultaneous measurement of LVOT gradient, which revealed a very strong correlation (r = 0.98, p < 0.0001) with 95% confidence limits of agreement +/- 12 mm Hg. In patients with HCM, LVOT gradient measurements are routinely obtained to characterize the severity of obstruction. However, these data demonstrate the marked variability of the LVOT obstruction, which must be considered when determining appropriate therapy in symptomatic patients.

Abstract 2552: Hypertrophic Cardiomyopathy in Children: Do Adult Risk Factors for Cardiac Death Apply

Introduction : Annual mortality in children with hypertrophic cardiomyopathy (HCM) has been reported to be 1– 6%. Risk factors for death in adult HCM patients have been characterized; their application to pediatric HCM is unknown. The purpose of this study was to correlate adult risk factors with outcomes in our pediatric population using a standard management strategy. Methods : A retrospective cohort study of children with HCM was performed. Death and cardiac transplant were the primary outcomes. Diagnosis was based on asymmetric septal or concentric hypertrophy as determined by echocardiography. Exclusion criteria included: genetic syndrome, mitochondrial or metabolic disorder, infants of diabetic mothers, congenital heart disease, systemic hypertension, diagnosis &gt;18 years of age, or follow-up &lt;1 year. Results : From 1/1/85 to 10/1/06, 96 patients met inclusion criteria. Mean age at diagnosis was 10.6 ± 5.4 years. Mean follow-up was 6.5 ± 5.2 years. 11 patients had an adverse outcome (7 deaths, 4 transplants). Kaplan-Meier analysis predicts an 82% survival over 20 years. Evidence of left ventricular outflow tract obstruction (LVOTO) occurred in =6% of patients, syncope in 23% and a family history for malignant HCM in 17%. Aborted sudden death occurred in 6%. 10% had non-sustained ventricular tachycardia. 58% of patients underwent at least one exercise treadmill test. All patients were restricted from strenuous activity. 95% of patients were on a β-blocker or calcium channel blocker, with 10% on both. Additional intervention depended on symptoms, family history, and degree of LVOTO. 17% had an implantable defibrillator (ICD). 10% were given a pacemaker due to LVOTO, and 5% underwent left ventricular myectomy. Only extreme LVH (&gt;6 z-scores for BSA) and a blunted blood pressure response to exercise were statistically significant for worse outcomes (both p&lt;0.02). Conclusions : A low mortality/transplantation rate occurred in children with isolated HCM whose management consisted of exercise restriction and medication, with or without an ICD. Management that included myectomy was uncommon. Patients with extreme LVH and a blunted blood pressure response to exercise are high-risk individuals.