Relationship between outflow obstruction and left ventricular functional impairment in hypertrophic cardiomyopathy: a Doppler echocardiographic study

Left ventricular outflow tract (LVOT) obstruction is predictive of a worse outcome in hypertrophic cardiomyopathy (HCM). In a detailed Doppler echocardiographic study of 178 selected HCM patients, the group of patients (n = 73) with the obstructive form (resting peak gradient > or = 30 mmHg) presented more hypertrophy and poorer systolic and diastolic left ventricular (LV) functions than the HCM group (n = 105) without obstruction. LVOT peak gradient was positively correlated with hypertrophy (P < 0.0001) and negatively to tissue Doppler mitral annulus systolic (P = 0.0001) and early diastolic (P < 0.0001) velocities. The gradient significantly correlated with E/Ea ratio (r = 0.67; P < 0.0001). By multiple regression, LVOT gradient was related to E/Ea, LV maximal thickness and left atrial size. In comparison with patients without obstruction, patients with obstruction presented greater hypertrophy (P < 0.0001), lower systolic and early diastolic mitral annulus velocities (both P < 0.0001), higher E/Ea ratio (P < 0.0001) and higher global function index (P < 0.0001). In HCM, beyond the effects on hypertrophy, LVOT obstruction is an independent determinant of LV functional abnormalities.     

Left Ventricular Outflow Tract Obstruction Following Mitral Valve Replacement with Carpentier-Edwards Prosthesis

Left ventricular outflow tract (LVOT) obstruction is a rare complication of mitral valve replacement. In this article, we describe three patients in whom left ventricular outflow tract obstruction occurred following Carpentier-Edwards porcine mitral valve replacement. All three patients presented with symptomatic mitral regurgitation (angiographic grade 3–4) requiring mitral valve replacement. Preoperatively there was no evidence of hypertrophic obstructive cardiomyopathy by physical exam, echocardiography, or by cardiac catheterization. At the time of surgery all three were shown to have severe mitral valve prolapse. The native anterior mitral leaflet was left intact and pledgeted to the mitral annulus. Following surgery a new systolic murmur was appreciated. Echocardiographic exam visualized obstruction of the left ventricular outflow tract by the prosthetic strut in two cases and by a flail anterior leaflet in one case. Continuous-wave Doppler measured a calculated peak gradient of 72 to 81 mmHg across the left ventricular outflow tract. In one case simultaneous Doppler and cardiac catheterization confirmed the diagnosis and severity of left ventricular outflow tract obstruction. Mechanisms of left ventricular outflow tract obstruction following Carpentier-Edwards porcine mitral valve replacement are discussed. These three cases highlight the importance of echo-Doppler techniques in understanding the mechanism of newly detected systolic murmurs following mitral valve replacement.     

Left Ventricular Outflow Tract Tachycardia Including Ventricular Tachycardia from the Aortic Cusps and Epicardial Ventricular Tachycardia

Idiopathic outflow tract ventricular tachycardia (VT) can arise from the right (RVOT) or left ventricular outflow tract (LVOT). The electrocardiographic (ECG) pattern of RVOT VT is typical in most patients, showing a monomorphic left bundle branch block (LBBB) QRS morphology with an inferior axis. Radiofrequency catheter ablation can be performed with a high success rate and provides a curative therapeutic approach. However, not all VTs with LBBB and inferior axis can be ablated from the RVOT. It has become apparent that LVOT VTs including VT originating from the aortic sinus of Valsalva or epicardium represent underrecognized VT entities which are also amenable to successful catheter ablation. Twelve-lead ECG criteria can contribute to distinguish between sites of VT origin.LVOT arrhythmias represent an increasingly recognized VT entity which can be safely and successfully treated by catheter ablation. Identification of VT origin using ECG criteria and differentiation of LVOT versus RVOT origin is essential in the careful planning of the ablation strategy.     

Ventricular tachycardias mimicking those arising from the right ventricular outflow tract

INTRODUCTION: Ablation of ventricular tachycardia (VT) arising from the right ventricular outflow tract (RVOT) has proven highly successful, yet VTs with similar ECG features may originate outside the RVOT. METHODS AND RESULTS: We reviewed the clinical, echocardiographic, and ECG findings of 29 consecutive patients referred for ablation of monomorphic VT having a left bundle branch block pattern in lead V1 and tall monophasic R waves inferiorly. Nineteen patients (group A) had VTs ablated from the RVOT, and 10 patients (group B) had VTs that could not be ablated from the RVOT. The QRS morphology during VT or frequent ventricular premature complexes was the only variable that distinguished the two groups. During the target arrhythmia, ECGs of group B patients displayed earlier precordial transition zones (median V3 vs V5; P < 0.001), more rightward axes (90 +/- 4 vs 83 +/- 5; P = 0.002), taller R waves inferiorly (aVF: 1.9 +/- 1.0 vs 2.4 +/- 0.5; P = 0.020) and small R waves in lead V1 (10/10 vs 9/19; P = 0.011). Radiofrequency catheter ablation from the RVOT failed to eliminate VT in any group B patient, but ablation from the left ventricular outflow tract (LVOT) eliminated VT in 2 of 6 patients in whom left ventricular ablation was attempted. CONCLUSION: The absence of an R wave in lead V1 and a late precordial transition zone suggest an RVOT origin of VT, whereas an early precordial transition zone characterizes VTs that mimic an RVOT origin. The latter VTs occasionally can be ablated from the LVOT. Recognition of these ECG features may help the physician advise patients and direct one's approach to ablation.     

Substrate in the interventricular septum for left ventricular and right ventricular outflow tract tachycardia: ablation from the right side of the septum

Simultaneous epicardial and endocardial mapping demonstrated that in a substantial number of ventricular tachycardias (VTs) endocardial, intramural, and epicardial structures are involved in the substrate of the reentrant circuits. Both right and left ventricular breakthrough has also been described during VT originating in the interventricular septum. We report the case of a patient with a nonischemic left ventricular aneurysm presenting with a left ventricular outflow tract (LVOT) tachycardia and a right ventricular outflow tract (RVOT) tachycardia. Mapping from the anterior interventricular vein and the endocardium of the RVOT revealed mid-diastolic potentials at the epicardium of the LVOT and the endocardium of RVOT, where the criteria of central isthmus sites could be demonstrated. Ablation targeting an isolated late potential during sinus rhythm in RVOT eliminated both the LVOT tachycardia and the RVOT tachycardia. In this patient with a nonischemic left ventricular aneurysm, the substrate of a LVOT tachycardia and RVOT tachycardia is described, and successful catheter ablation of the right and left ventricular tachycardia from the septal wall of RVOT is reported.     

Right and left ventricular outflow tract tachycardias: evidence for a common electrophysiologic mechanism

Introduction: "Idiopathic" ventricular arrhythmias most often arise from the right ventricular outflow tract (RVOT), although arrhythmias from the left ventricular outflow tract (LVOT) are also observed. While previous work has elucidated the mechanism and electropharmacologic profile of RVOT arrhythmias, it is unclear whether those from the LVOT share these properties. The purpose of this study was to characterize the electropharmacologic properties of RVOT and LVOT arrhythmias.
Methods and Results: One hundred twenty-two consecutive patients  (61 male; 50.9 ± 15.2 years)  with outflow tract arrhythmias comprise this series, 100 (82%) with an RVOT origin, and 22 (18%) with an LVOT origin. The index arrhythmia was similar: sustained ventricular tachycardia (VT)  (RVOT = 28%, LVOT = 36%)  , nonsustained VT  (RVOT=40%, LVOT=23%)  , and premature ventricular complexes  (RVOT = 32%, LVOT = 41%) (P = 0.32)  . Cardiac magnetic resonance imaging and microvolt T-wave alternans results (normal/indeterminate) were also comparable. In addition, 41% with RVOT foci and 50% with LVOT foci were inducible for sustained VT (P = 0.48), and induction of VT was catecholamine dependent in a majority of patients in both groups (66% and 73%; RVOT and LVOT, respectively; P = 1.0). VT was sensitive to adenosine (88% and 78% in the RVOT and LVOT groups, respectively, P = 0.59) as well as blockade of the slow-inward calcium current (RVOT=70%, LVOT=80%; P = 1.00) in both groups.
Conclusions: Electrophysiologic and pharmacologic properties, including sensitivity to adenosine, are similar for RVOT and LVOT arrhythmias. Despite disparate sites of origin, these data suggest a common arrhythmogenic mechanism, consistent with cyclic AMP-mediated triggered activity. Based on these similarities, these arrhythmias should be considered as a single entity, and classified together as "outflow tract arrhythmias."     

The significance of systolic anterior motion (SAM) on the mitral valve echo pattern in hypertrophic cardiomyopathy

The systolic anterior motion (SAM) of valve structures in the mitral echogram in hypertrophic cardiomyopathy (HCM) has previously been considered to be anterior motion and re-opening of mitral valve leaflets, causing left ventricular outflow tract (LVOT) obstruction and mitral regurgitation. Fifteen patients with HCM underwent cardiac catheterisation and were also examined by M-scan and mechanical real-time B-scan techniques. In all patients SAM was seen during M-scan echocardiography. The mitral valve leaflets were visualised during the entire cardiac cycle during real-time B-scanning without showing any re-opening in systole. Thickened papillary muscles have been observed in 12 patients and prominent chordae tendineae moving in the opposite direction to the anterior mitral valve leaflet in 10 patients. Four patients with SAM did not show mitral regurgitation during left ventricular angiography. In two patients without fixed haemodynamic obstruction, a complete SAM touching the interventricular septum was observed with prolonged apposition in one case. These findings suggest that SAM is due to the motion of chordae tendineae and/or papillary muscles traversing the single dimensional ultrasonic beam in systole, thus producing single linear or multiple spotty echoes within SAM. The mechanism of the upward motion of the subvalvular mitral valve apparatus in systole appears to be due to forceful contraction of the apical left ventricular posterior wall. The observation of SAM in patients without HCM also indicates that its presence during single dimensional echocardiography is neither diagnostic nor specific for HCM, LVOT obstruction or mitral regurgitation, and contradicts the assumption that the anterior mitral valve leaflet plays a significant role in the mechanism of LVOT obstruction. The salient feature of all conditions associated with abnormal mitral subvalvular motion is hyperkinetic contraction of the apical left ventricular posterior wall. Hyperkinetic left ventricular ejection appears to be the main factor in the complex development of an LVOT gradient in hypertrophic cardiomyopathy.     

Left ventricular outflow tract tachycardia originating from the right coronary cusp: identification of location of origin by endocardial noncontact activation mapping from the right ventricular outflow tract

Idiopathic left ventricular outflow tract (LVOT) tachycardia has been shown to originate from a supravalvular site in some patients. Considerable attention recently has focused on identifying this variant of LVOT tachycardia on 12-lead ECG. We report the case of 15-year-old boy in whom a noncontact three-dimensional mapping electrode deployed in the right ventricular outflow tract (RVOT) assisted in identifying a supravalvular LVOT tachycardia. Observation of two early breakthrough sites in the RVOT and right ventricular septum suggested a right aortic cusp origin of the tachycardia. Pace mapping in the right aortic cusp identified a successful ablation site.     

Fixed left ventricular outflow tract obstruction mimicking hypertrophic obstructive cardiomyopathy: pitfalls in diagnosis

We present a case series that highlights the diagnostic challenges with left ventricular hypertrophy (LVH) and left ventricular outflow tract obstruction (LVOTO). Fixed structural lesions causing LVOTO with secondary LVH may mimic hypertrophic obstructive cardiomyopathy (HOCM). Management of these two entities is critically different. Misdiagnosis and failure to recognize fixed left ventricular outflow tract (LVOT) lesions may result in morbidity as a result of inappropriate therapy and delay of definitive surgical treatment. It is thus necessary to identify the correct type and level of obstruction in the LVOT by careful correlation of clinical examination, Doppler evaluation, and advanced imaging findings.     

Left Ventricular Outflow Tract Gradient Provoked by Upright Position or Exercise in Treated Patients with Hypertrophic Cardiomyopathy without Obstruction at Rest

Objectives: The aim of the study was to assess inducibility of left ventricular outflow tract (LVOT) gradient by change of position from supine to upright and by treadmill exercise in treated patients with hypertrophic cardiomyopathy (HCM) without obstruction at rest. Methods: We studied 37 treated HCM patients (21 men and 16 women, mean age 44 ± 12 years) with LVOT gradient <30 mmHg at rest in supine position. The patients were then placed in upright position and the gradient was reexamined. The patients who developed LVOT gradient ≥30 mmHg during this maneuver were not exercised, whereas the remaining patients (nonobstructive in orthostatic position) performed moderate-intensity exercise on a treadmill, with continuous monitoring of the LVOT gradient. For comparison with resting measurements, gradients at peak exercise (in upright position) and at recovery (in supine position) were used. The resting minimal distance between the mitral valve and ventricular septum at systole was used to assess the degree of narrowing of LVOT. Results: The orthostatic position provoked LVOT gradient ≥30 mmHg in 8 of 37 patients. At peak exercise, 10 of the remaining 29 patients developed significant LVOT gradient. At recovery in supine position, this significant gradient disappeared in 6 of 10 patients, despite only a short delay in measurement. Of resting echocardiographic parameters, only systolic mitral–septal distance differentiated between the provocable and nonprovocable subgroups. Patients with provocable gradient (either by changing position or by exercise) presented with lower values of this parameter than the nonprovacable subgroup. Conclusions: In nonobstructive HCM patients under treatment, the LVOT gradient was inducible by upright position in 21.6% and by upright moderate exercise in 34.5%. The minimal septal–mitral distance may be useful to identify patients with provocable obstruction.     

Use of three-dimensional echocardiography for analysis of outflow obstruction in congenital heart disease

To evaluate the feasibility and accuracy of 3-dimensional (3D) echocardiography in analysis of left and right ventricular outflow tract (LVOT and RVOT) obstruction, 3D echocardiography was performed in 28 patients (age 4 months to 36 years) with outflow tract pathology. Type of lesion and relation to valves were assessed. Length and degree of obstruction were measured. Three-D data sets were adequate for reconstruction in 25 of 28 patients; 47 reconstructions were made. In 13 patients with LVOT obstruction, 3D echocardiography was used to study subvalvular details in 8, valvular in 13, and supravalvular in 1. Four of these 13 patients had complex subaortic obstruction. In 12 patients with RVOT lesions, 3D echocardiography was used to study subvalvular details in 11, valvular in 12, and supravalvular in 2. Three-dimensional reconstructions were suitable for analysis in 100% of subvalvular LVOT, 77% valvular LVOT, 100% supravalvular LVOT, 100% subvalvular RVOT, 50% valvular RVOT, and 50% supravalvular RVOT. Twenty patients underwent operation, and surgical findings served as morphologic control for thirty-four 3D reconstructions (LVOT 17, RVOT 17). Operative findings revealed an accuracy at subvalvular LVOT of 100%, valvular LVOT 90%, supravalvular LVOT 100%, subvalvular RVOT 100%, valvular RVOT 100%, and supravalvular RVOT 100%. Quantitative measurements could adequately be performed. Three-D echocardiography is feasible and accurate for analyzing both outflow tracts of the heart. Particularly, generation of nonconventional horizontal cross sections allows a good definition of extension and severity of lesions.     

肥厚梗阻性心肌病与二尖瓣病变及二尖瓣反流

目的:探讨左心室流出道梗阻对二尖瓣叶及二尖瓣反流的影响。方法:采用数字化超声心动图技术分析左心室流出道梗阻患者二尖瓣前叶形态结构及二尖瓣反流的特点。结果:68例左心室流出道梗阻患者,其中2例二尖瓣前叶赘生物形成合并穿孔,66例二尖瓣前叶近瓣缘部分轻度增厚。全部患者均有明显二尖瓣前叶收缩期前向运动(SAM)及二尖瓣偏心反流。结论:左心室流出道梗阻可引起二尖瓣前叶病变。左心室流出道梗阻患者二尖瓣前叶SAM可导致二尖瓣反流。     

肥厚型心肌病患者小动脉弹性指数水平与左心室流出道梗阻的关系

目的：探讨肥厚型心肌病（HCM）患者小动脉弹性指数（C2）水平与左心室流出道梗阻的关系. 方法：纳入2010年1月至2013年7月间因肥厚型心肌病于我院心内科住院的患者69例,收集相关临床资料,比较C2水平与相关指标的关联性.再根据左心室流出道梗阻情况的不同,将HCM患者分为梗阻性HCM与非梗阻性HCM,比较两组患者的C2水平. 结果：N末端B型利钠肽原（NT-proBNP）、左室流出道最大压差（LVOTPG）与C2呈显著负相关,左室短轴缩短率（LVFS）与C2呈显著正相关,左室后壁宽度（LVPWD）与C2无显著相关性,超敏肌钙蛋白I（c-TNI）、左室射血分数（LVEF）、左室舒张末期内径（LVEDD）与C2呈非线性相关.梗阻性HCM患者的C2水平显著低于非梗阻性HCM患者. 结论：C2与LVOTPG密切相关,该指标可作为HCM患者左心室流出道梗阻病情进展的动态评价指标.     

Left Ventricular Outflow Tract Obstruction After Myocardial Infarction Due to a Hyperdynamic Basal Septum

Acquired left ventricular outflow (LVOT) obstruction may occur following mitral valve repair or replacement. We describe a case where following a large myocardial infarction the hyperdynamic basilar septum was the cause of LVOT.     

Autonomic and pharmacological responses of idiopathic ventricular tachycardia arising from the left ventricular outflow tract

Background: It is well recognized that the mechanism of idiopathic ventricular tachycardia (VT) arising from the right ventricular outflow tract (RVOT) is mostly due to cyclic AMP-mediated triggered activity. The mechanism of VT arising from the left ventricular outflow tract (LVOT) has not been well clarified whether it is the same as VT of RVOT.
Methods: We studied autonomic modulations and pharmacological interventions on VT/premature ventricular contractions (PVCs) from LVOT to explore its possible mechanism in six patients (age: 49 ± 14, three males). None of them had structural heart diseases.
Results: Isoproterenol application easily induced VT and/or PVCs from LVOT. Valsalva maneuvers suppressed isoproterenol-induced VT in two and PVCs in two, and carotid sinus massage (CSM) suppressed PVCs in one patient. Adenosine triphosphate inhibited both VT and PVCs in all six patients. Propranolol, lidocaine, and procainamide eliminated VT/PVCs in four, three, and four patients, respectively. Verapamil terminated VT in one and PVCs in another one patient, but aggravated PVCs to VT in one patient.
Conclusion: The results suggest that the mechanism of VT from LVOT is mostly due to cAMP-mediated triggered activity as similar to that in VT from RVOT.     

Sudden iatrogenic suicidal right ventricle

It is important to obtain a good withdrawal pressure tracing while performing cardiac catheterization in cases with right ventricular outflow tract (RVOT) obstruction to document the site and severity of obstruction. However efforts to manipulate the catheter in the RVOT (either to obtain the gradients or to position the catheter for an outflow angiogram) can sometimes precipitate severe dynamic RVOT obstruction with complete cessation of forward flow leading to life threatening hypotension.The following hemodynamic traces highlight this rare phenomenon which needs to be borne in mind at all times while performing cardiac catheterization in such patients.     

应用Doppler超声观察肥厚性心肌病患者左心室内血流速度的改变

本文应用 Doppler 超声及实时二维 Doppler 彩色血流显象(CDFI)法观察了19例肥厚性心肌病(HCM)患者左心室内收缩期血流速度及左室收缩状态,结果示,不论有无左室流出道狭窄,HCM 患者左室内(包括左室流出道、室中及心尖部)收缩期血流峰值速度均明显增高,在左室流出道内可呈高速的湍流,于 CDFI 上表现为严重的 Aliasing 现象及轻度 Mosaic 现象,说明 HCM 患者左心室呈高动力型收缩状态。应用 CDFI 技术可指导脉冲波(PW)及连续波(CW)Doppler 对异常血流的采样,提高对 HCM 患者左室内高速血流速度测定的准确性。     

Now you see me,now you don't: The case of a vanishing outflow gradient in a patient with hypertrophic cardiomyopathy

Cardiogenic shock is well described in hypertrophic cardiomyopathy (HCM) as acute hemodynamic collapse can develop in the setting of acute worsening of left ventricular outflow tract (LVOT) obstruction. We present the case of a 60‐year‐old man with drug refractory LVOT obstruction due to hypertrophic cardiomyopathy. On the evening prior to planned alcohol septal ablation, the patient presented in cardiogenic shock. Interestingly, his previously recorded LVOT gradients of 50 mm Hg at rest and 118 mm Hg at peak exercise were absent. With recovery of left ventricular function, significant left ventricular outflow obstruction returned. The patient then underwent successful septal reduction therapy. © 2016 Wiley Periodicals, Inc.