Dynamic Left Ventricular Inflow Obstruction Associated with a Left Atrial Myxoma

Abstract

A 49-year-old female presented with lower extremity weakness, worsening dyspnea, stigmata of systemic embolism, and an acute episode of dysarthria. Brain computed tomography and magnetic resonance imaging demonstrated small embolic strokes while transthoracic echocardiographic examination showed a large left atrial (LA) mass. The patient was scheduled for surgical excision of the mass. Intraoperative two-dimensional and three-dimensional transesophageal echocardiography (TEE) (Siemens Sequoia, Mountain View, CA and Tom Tek Corporation, Boulder, CO) demonstrated a 4 × 6 cm2 pedunculated LA mass attached by a pedicle to the superior fossa of the interatrial septum [Fig. 1 and Video Loop 1 (Please see video loops available at www.anesthesia-analgesia.org)]. During diastole, the mass prolapsed through the mitral valve resulting in a turbulent color flow Doppler pattern (Video Loop 2). Continuous wave doppler revealed mild to moderate left ventricular (LV) inflow obstruction, with calculated mean and peak pressure gradients of 6 mm Hg and 9 mm Hg, respectively (Fig. 2). In general, mild mitral obstruction is suggested by a mean pressure gradient <6 mm Hg, moderate obstruction by a mean pressure gradient of 6–10 mm Hg, and severe obstruction by a gradient >10 mm Hg. Proximal isovelocity surface area can provide information about the degree of obstruction, but the asymmetry of the proximal isovelocity surface area hemisphere in this case may have resulted in an inaccurate estimate of the diminished LV inflow area. The use of pressure half-time is also commonly used to estimate the severity of mitral obstruction, however, this technique has not been validated in patients with dynamic LV inflow obstruction.Figure 1.: Intraoperative two-dimensional transesophageal mid-esophageal four-chamber view demonstrating the left atrial myxoma (arrow) prolapsing through the mitral valve during diastole. LA: left atrium; LV: left ventricle; RV: right ventricle.Figure 2.: Intraoperative continuous wave Doppler image from the transesophageal mid-esophageal four-chamber view demonstrating the left ventricular inflow velocity profile along the prolapsing left atrial myxoma. Pressure gradients (ΔP) calculated from the modified Bernoulli Equation (ΔP = 4V 2; V = peak velocity), were obtained from values averaged over three cardiac cycles. The calculated mean (6 mm Hg) and peak (9 mm Hg) pressure gradients are consistent with mild-to-moderate obstruction.A complete excision of the LA mass and its atrial septal attachment was performed and the resultant atrial septal defect was closed with pericardial patches. After cardiopulmonary bypass, TEE confirmed an intact interatrial septum. Pathologic examination confirmed the mass to be a myxoma. The patient recovered uneventfully and was discharged home on postoperative Day 5. Seventy-five percent of myxomas are found in the LA, but 10–20% originate in the right atrium, and 5% in either ventricle. In contrast to this report, LA myxomas typically attach via a narrow base to the interatrial septum at the border of the fossa ovalis, and are rarely invasive. Patients with myxomas who become symptomatic usually present with congestive heart failure (67%) because of LV inflow obstruction, signs of tumor embolization (29%), or constitutional symptoms (41%) (1,2). Intraoperative TEE is used for identifying satellite tumors and confirming the structural integrity of the interatrial septum after surgical excision of a myxoma (3). Three-dimensional TEE may be helpful for delineating the extent of the myxoma's attachment, thereby permitting more accurate surgical planning.