Hensley's Practical Approach to Cardiothoracic Anesthesia

Anesthetic Considerations for Surgical Myectomy in Patients With Hypertrophic Cardiomyopathy Elena Ashikhmina Swan, Jeffrey B. Geske, and Hartzell V. Schaff 16

I. Introduction 343 II. Hypertrophic Cardiomyopathy 344 A. Epidemiology, Morphology, Histopathology, Genetics 344 B. Pathophysiology 347 C. Clinical Presentation and Diagnosis 347 D. Natural History 348 E. Surgical Treatment 348 III. Anesthetic Considerations 349 A. Preoperative Encounter 349

B. Intraoperative Management 350 C. Intraoperative Monitoring 351 D. Early Postoperative Care 352 IV. Surgical Subgroups and Anesthetic Considerations 352 A. Apical Myectomy 352 B. Pulmonary Hypertension 352 C. Hypertrophic Cardiomyopathy in Children 352 D. Right Ventricular Hypertrophy 353 V. Summary 353

KEY POINTS 1. Obstructive hypertrophic cardiomyopathy (HCM) is manifested by fatigue, dyspnea, chest pain, and syncope exacerbated by dynamic obstruction of the left ventricular outflow tract or left ventricular cavity, systolic anterior motion of the mitral valve, mitral regurgitation, diastolic dysfunction, and postcapillary pulmonary hypertension. 2. Transaortic septal myectomy, or a combination of transaortic and apical myectomy depending on the distribution of myocardial hypertrophy is indicated for patients with limiting symptoms despite medical treatment. 3. The anesthetic management of surgical myectomy for HCM is often challenging. Pronounced hemodynamic swings precipitating low cardiac output related to decreased systemic vascu lar resistance and worsening of outflow obstruction due to sympathetic stimulation should be anticipated and avoided by careful selection of anesthetic and analgesic agents. Their potential side effects should be mitigated by vasopressors and volume administration. 4. Intraoperative direct left ventricle (LV) to aorta gradient monitoring with simultaneous transesophageal echocardiography to assess the degree of the LV outflow obstruction and MR is key for successful myectomy. It may be necessary to resume cardiopulmonary bypass for additional myectomy if residual gradient of > 25 mm Hg is present. 5. Surgical myectomy for HCM is commonly a relatively short procedure with cardiopulmonary bypass time averaging < 45 minutes. Patients usually do not require inotropic support. Fast-track recovery pathway should be considered. I. Introduction Hypertrophic cardiomyopathy (HCM) is the most common genetic cardiac disease, with a preva lence of 1 in 200-500 adults. 1,2 It is defined as left ventricular (LV) hypertrophy without an under lying cause, such as systemic hypertension or valvular aortic stenosis. 3 In the obstructive form of HCM, a combination of septal hypertrophy and abnormal systolic anterior motion (SAM) of the mitral valve produce left ventricular outflow tract (LVOT) obstruction and mitral valve regurgi tation (MR). The distribution of LV hypertrophy is variable in patients with HCM, and in some patients, it is more prominent at the mid-ventricular or apical level. 4

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