Presence Of Left Ventricular Outflow Tract Obstruction Research Articles

Left ventricular outflow tract obstruction in Takotsubo syndrome with cardiogenic shock: prognosis and treatment

BackgroundPatients with Takotsubo syndrome (TTS) who develop cardiogenic shock may present with left ventricular outflow tract obstruction (LVOTO). The prognosis and treatment of this population have not been defined in...

Machine learning evaluation of LV outflow obstruction in hypertrophic cardiomyopathy using three-chamber cardiovascular magnetic resonance

Left ventricular outflow tract obstruction (LVOTO) is common in hypertrophic cardiomyopathy (HCM), but relationships between anatomical metrics and obstruction are poorly understood. We aimed to develop machine learning methods to evaluate LVOTO in HCM patients and quantify relationships between anatomical metrics and obstruction. This retrospective analysis of 1905 participants of the HCM Registry quantified 11 anatomical metrics derived from 14 landmarks automatically detected on the three-chamber long axis cine CMR images. Linear and logistic regression was used to quantify strengths of relationships with the presence of LVOTO (defined by resting Doppler pressure drop of > 30 mmHg), using the area under the receiver operating characteristic (AUC). Intraclass correlation coefficients between the network predictions and three independent observers showed similar agreement to that between observers. The distance from anterior mitral valve leaflet tip to basal septum (AML-BS) was most highly correlated with Doppler pressure drop (R2 = 0.19, p < 10–5). Multivariate stepwise regression found the best predictive model included AML-BS, AML length to aortic valve diameter ratio, AML length to LV width ratio, and midventricular septal thickness metrics (AUC 0.84). Excluding AML-BS, metrics grouped according to septal hypertrophy, LV geometry, and AML anatomy each had similar associations with LVOTO (AUC 0.71, 0.71, 0.68 respectively, p = ns), significantly less than their combination (AUC 0.77, p < 0.05 for each). Anatomical metrics derived from a standard three-chamber CMR cine acquisition can be used to highlight risk of LVOTO, and suggest further investigation if necessary. A combination of geometric factors is required to provide the best risk prediction.

P1715 Aortic stenosis with concomitant LVOTO: an alternative treatment to surgery

Abstract The dilemma of the patient with both aortic stenosis (AS) and significant left ventricular outflow tract obstruction (LVOTO) is usually managed through conventional surgery. Patients included in TAVI studies are highly selected, and the presence of LVOTO is a common exclusion criteria. Permanent pacing is referred as a possible treatment in medically refractory symptomatic patients with obstructive hypertrophic cardiomyopathy. We report a case of AS and LVOTO that was submitted to transcatheter aortic valve replacement (TAVR) due to high surgical risk, and submitted to a definitive pacemaker implantation after the procedure. This case is about a female patient with 82 years old and a history of a severe aortic stenosis with a significant ventricular hypertrophy that causes LVOTO. She had a previous history of hypertension, dyslipidemia, osteoporosis and breast cancer. The patient presented with angina (grade II in Canadian Cardiovascular Society Angina Grade), dyspnea and weakness (classe II of New York Heart Association functional classification). Transthoracic Echocardiography (TTE) presented with severe aortic stenosis with a basal septal ventricular hypertrophy of 18 millimeters, a systolic anterior motion of the mitral valve (SAM) both conditioning LVOTO (maximal gradient of 75 mmHg at rest) and moderate mitral regurgitation (MR). Coronariography showed no coronary lesions. Transfemoral TAVR was successfully implanted under general anesthesia and transesophageal echocardiography monitoring (TOE). During ballooning pre-dilatation a complete atrioventricular block developed. Immediately after the valve implantation TOE showed a well-positioned prothesis without intra or peri-prosthetic regurgitation but with an intraventricular gradient (IVG) above 50mmHg and a moderate to severe MR. SAM, IVG and MR were medically managed and the patient went to the intensive cardiac unit (ICU) with a IVG of 50mmHg and a moderate MR. In the next 24H in the ICU, the patient had a clinical deterioration and TTE found an increased intraventricular gradient (140 mmHg) and a severe mitral regurgitation. It was decided to implant a Dual Chamber pacemaker (DDD PM) and adjust beta-blocker and fluid therapy. A progressive clinical improvement was observed and clinical stabilization attained after 48H. At discharge (7 days after TAVR), TTE showed decreased intraventricular gradients (30 mmHg at rest, 50 mmHg with Valsalva maneuver), telesystolic SAM and a moderate mitral regurgitation. At 6 moths follow up, patient was free of cardiovascular events and had no symptoms of heart failure. This case shows that TAVR is a safe procedure in patients with LVOTO, but we have to be aware of potentially severe hemodynamic consequences of sudden reduce in after load pressure in these patients. In high risk surgical patients, DDD-PM can accomplish acute and at least medium term clinical and hemodynamic stabilization. Abstract P1715 Figure. Echocardiography images

Cardiac pacing in patients with hypertrophic obstructive cardiomyopathy.

[first paragraph of article]About one-third of patients with hypertrophic cardiomyopathy (HCM) have resting left ventricular outflow tract obstruction (LVOTO). The presence of LVOTO in HCM facilitates the progression of heart failure and increases the risk of death. LVOTO is defined as a peak instantaneous Doppler LV outflow tract gradient ≥30 mmHg, but the threshold for invasive treatment is usually considered to be ≥50 mm Hg.

The Mitral Valve in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) has evoked both fascination and controversy since its first modern description >50 years ago.1 Originally described as “functional aortic subvalvar stenosis” by Brock, the majority of articles about HCM in the ensuing first decade emanated from observations made in the operating room or in the cardiac catheterization laboratory.1 The actual cause of left ventricular outflow tract (LVOT) obstruction in patients with this condition had not yet been clarified. Ironically, the mechanisms of LVOT obstruction in HCM were only elucidated several years after surgery was first performed in these patients. In fact, an early report by Morrow described the septal myotomy procedure as surgical treatment for HCM and proposed that the myotomy interfered with the sphincter-like muscular contraction ring in the LVOT.1 Article see p 40 Noninvasive cardiovascular imaging studies have greatly advanced our knowledge about HCM.2 Hypertrophic cardiomyopathy is now felt to have tremendous genetic,3 clinical, morphological, and hemodynamic heterogeneity.1 Nevertheless, the presence of LVOT obstruction in patients with HCM has continued to inspire interest. The often contentious debates surrounding LVOT obstruction have centered on its very existence, its causes, its clinical impact and prognosis, and its optimal management.1 These issues have inextricably included the mitral valve, which has long been felt to play a pivotal role in the pathophysiology of LVOT obstruction in patients with HCM. In the present issue of Circulation , Maron et al use cardiovascular magnetic resonance (CMR) imaging to characterize mitral valve leaflets in patients with HCM.4 This study assessed the lengths of the anterior mitral leaflet (AML) and posterior mitral leaflet in 172 consecutive patients with HCM. Their findings were compared with 172 normal control subjects matched for age, sex, and body surface area. In addition, the study included a small cohort of …

Imaging Phenotype Versus Genotype in Hypertrophic Cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is a common monogenetic cardiac disease with a prevalence of 0.2%1 that usually is inherited as an autosomal dominant trait with variable penetrance and expression. Clinically, HCM is defined by the presence of left ventricular (LV) hypertrophy (LVH) unexplained by abnormal loading conditions.1 The natural history varies from an asymptomatic course to drug-refractory angina/dyspnea, sudden cardiac death (SCD), and end-stage heart failure. The incidence of HCM-related SCD is approximately 1% to 2% in children and adolescents and 0.5% to 1% in adults.2,3 In this review, we examine the impact of advanced diagnostic imaging technologies on HCM, with particular emphasis on the detection of particular genetic subtypes. In ≈60% of cases, HCM is inherited as an autosomal dominant trait caused by mutations in genes coding for cardiac sarcomere proteins (Figure 1).4–7 Mutations in genes encoding Z-disc proteins and proteins involved in calcium regulation account for <5% of cases. The absence of sarcomeric gene mutations can be explained by limitations of current mutation detection techniques or mutations in as yet unidentified genes, but in some cases, hypertrophy is caused by other diseases that mimic the phenotype of sarcomeric protein disease. Table 1 lists genetic disorders associated with HCM. Figure 1. A schematic illustration of a cardiac sarcomere. View this table: Table 1. Currently Known Genes Implicated in HCM More than 600 different sarcomeric gene mutations are reported in patients with HCM.8–16 The majority are missense mutations, but nonsense, frameshift, and in-frame insertion/deletion mutations also occur. Most mutations are characterized by incomplete penetrance and variable clinical expression likely due to locus heterogeneity and the effect of mutations at different locations within the same gene. Most mutations probably have a dominant negative effect on sarcomere function, but in some cases, haploinsufficiency (ie, only a single functional …

Chronotropic incompetence and its relation to exercise intolerance in hypertrophic cardiomyopathy

BackgroundDiminished functional capacity is common in hypertrophic cardiomyopathy (HCM), although the underlying mechanisms are complicated. We studied the prevalence of chronotropic incompetence and its relation to exercise intolerance in patients with HCM. MethodsCardiopulmonary exercise testing was performed in 68 patients with HCM (age 44.8±14.6years, 45 males). Chronotropic incompetence was defined by chronotropic index (heart rate reserve)/(220-age-resting heart rate) and exercise capacity was assessed by peak oxygen consumption (peak Vo2). ResultsChronotropic incompetence was present in 50% of the patients and was associated with higher NYHA class, history of atrial fibrillation, higher fibrosis burden on cardiac MRI, and treatment with β-blockers, amiodarone and warfarin. On univariate analysis, male gender, age, NYHA class, maximal wall thickness, left atrial diameter, peak early diastolic myocardial velocity of the lateral mitral annulus, history of atrial fibrillation, presence of left ventricular outflow tract obstruction (LVOTO) at rest, and treatment with beta-blockers were related to peak Vo2. Peak heart rate during exercise, heart rate reserve, chronotropic index, and peak systolic blood pressure were also related to peak Vo2. On multivariate analysis male gender, atrial fibrillation, presence of LVOTO and heart rate reserve were independent predictors of exercise capacity (R2=76.7%). A cutoff of 62bpm for the heart rate reserve showed a negative predictive value of 100% in predicting patients with a peak Vo2 <80%. ConclusionsBlunted heart rate response to exercise is common in HCM and represents an important determinant of exercise capacity.

Enhanced oxidative stress in hypertrophic cardiomyopathy

Elevated plasma levels of inflammation and endothelial dysfunction markers have been reported in patients with hypertrophic cardiomyopathy (HCM). The aim of the current study was to determine whether HCM is associated with enhanced oxidative stress. We enrolled 54HCMpatients with sinus rhythm, including 21 subjects with a left ventricular outflow tract (LVOT) obstruction (gradient≥30mmHg), and 54 age- and sex-matched controls without cardiovascular diseases. Serum levels of 8-isoprostaglandin F2α (8-iso-PGF2α), a stable marker of oxidative stress, were determined.Serum 8-iso-PGF2α levels were elevated in HCM patients compared with controls (35.4±10.2 vs. 29.9±9.9 pg/ml, p<0.001). Patients with obstructiveHCMdisplayed higher 8-iso-PGF2α levels compared with the non-obstructiveHCMsubgroup (41.6±12.7 vs. 31.4±5.4 pg/ml, p<0.0001). Both anatomic (mitral-septal distance) and hemodynamic (subaortic gradient) indexes of LVOT obstruction, but not other echocardiographic variables, correlated with 8-iso-PGF2α levels (r=–0.43; p<0.05 and r=0.39; p<0.05, respectively).This study is the first to show that HCM is characterized by enhanced oxidative stress as evidenced by higher 8-iso-PGF2α, which achieves its highest values in the presence of LVOT obstruction in HCM patients.