الفهرس 
Anatomy of the heart and left ventricular outflow tract (LVOT)Only 14 pages are availabe for public view
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Abstract
Left ventricular outflow tract is the region just below the aortic valve, actually the region through which blood moves out of the left ventricle. It is bounded by the interventricular septum in the front and the anterior mitral leaflet in back. Left ventricular outflow tract obstructions (LVO-TOs)encompass a series of stenotic lesions starting in theanatomic left ventricular outflow tract (LVOT) and stretchingto the descending portion of the aortic arch.Obstruction may be subvalvar(subaortic stenosis), valvar, or supravalvar. Left ventricularoutflow tract obstruction can be defined as either fixed ordynamic obstruction to ejection of blood from the leftventricle. Although the clinical manifestations aresimilar to those of left ventricular systolic dysfunction, thediagnosis of LVOTO is critical because the treatment andmanagement are based on a very different rationale.Indeed, inotropic support, pharmacological or mechanicalafterload reduction, and volume restriction used in heartfailure would significantly compromise the hemodynamicsof a patient presenting with a low output state fromLVOTO. All of these lesions impose increasedafterload on the left ventricle and, if severe and untreated,result in hypertrophy and eventual dilatation and failure of theleft ventricle. It isimperative to consider all patients with LVOTO at a high riskfor developing infective endocarditis, and one should alwaysinstitute appropriate measures for prophylaxis. Transesophageal echocardiography (TEE) plays a key rolein the evaluation of hemodynamic instability, particularlyin the diagnosis of left ventricular outflow tract obstruction(LVOTO) where it can completely alter patient management. In some cases, TEE serves as a tool to evaluate theresponse to therapy in the perioperative and critical care settings. Treatment options for these various forms of obstruction include medical therapy, lifestyle modification, surgical repair, as well as heart transplantation for end-stage patients with heart failure. Additionally, the possibility for recurrent stenoses after operation is always present. For these reasons, therapy and interventions directed toward relief of LVOTO must be considered palliative, and lifelong patient follow-up is necessary. Anesthetic management of patients with LVOTO presents considerable challenges and requires maintenance of desired hemodynamic parameters and management of specific complications. Factors like tachycardia, hypovolemia, vasodilation and increased cardiac contractility leads to exacerbation of the obstruction.