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Austin J Anesthesia and Analgesia. 2017; 5(1): 1056.
Dynamic Left Ventricular Outflow Tract Obstruction during Non-Cardiac Surgery
Maquoi I, Basbous A, Amabili P, Brichant JF and Hans GA*
Department of Anesthesia and Intensive Care Medicine, CHU of Liege, Liege, Belgium
*Corresponding author: Hans GA, Department of Anesthesia and Intensive Care Medicine, CHU of Liege, Liege, Belgium
Received: August 08, 2017; Accepted: August 14, 2017; Published: August 21, 2017
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Dynamic Left Ventricular Outflow Tract (LVOT) obstruction with Systolic Anterior Motion of the mitral valve (SAM) was first reported in hypertrophic cardiomyopathy but is now increasingly recognized as a cause of hemodynatmic instability [1]. Echocardiographic hallmarks of SAM include systolic bending of the mitral valve leaflets across the LVOT, late systolic peaking flow velocity in the LVOT, mid-systolic closure of the aortic valve, and posteriorly directed mitral valve regurgitation. SAM is thought to result from the combination of predisposing anatomical factors such septal hypertrophy, abnormal chordae insertion, elongated mitral valve leaflets, and anterior displacement of the anterolateral papillary muscle and precipitating conditions. Precipitating conditions include hypovolemia, vasodilation, tachycardia, and increased contractility [2]. They are frequently encountered during surgery as a result of blood loss, anesthetics-induced vasodilation, mechanical ventilation, and catecholamine surge. Treatment of SAM with dynamic LVOT obstruction includes volume administration and use of vasopressors to increase the after load. ß-blockers can be used in the most severe cases to slow down the heart rate and decrease contractility.
Figure 1: A. Mid-esophageal long-axis view showing the bending of the MV
across the LVOT.
B. Mid-Esophageal long-axis view with color flow Doppler revealing a
massive mitral regurgitation posteriorly directed. The mosaic appearance in
the LVOT reflects flow acceleration related to dynamic obstruction of the left
ventricular outflow tract.
C. Mid-esophageal long-axis view after the initiation of ß-blockers. The MV
still bends across the LVOT but no longer comes in apposition with the
interventricular septum.
D. Mid-Esophageal long-axis view with color flow Doppler after the
administration of ß-blockers. There is less MR and flow acceleration into the
LVOT than in B. The Nyquist limit was set at 43.4cm/sec for all the color flow
Doppler images. Video 1 and 2, available as supplementary online material
show mid-papillary short-axis transgastric view and mid-esophageal long-axis
view with and without color flow Doppler before and after the administration of
ß-blockers, respectively.
MR= Mitral Valve Regurgitation; MV= Mitral Valve; AMVL= Anterior Mitral
Valve Leaflet; LVOT= Left Ventricular Outflow Tract.
The accompanying images are from a 72-year-old man who underwent bilateral nephrectomy for infected renal cysts resulting in a septic shock state and developed profound hypotension following the loss of 1.5 liter of blood over a short period. A rescue transoesophageal echo was performed because both the administration of a massive amount of fluid, blood and blood products and an infusion of noradrenaline at 0.3 μg•kg-1•min-1 failed to correct blood pressure. Based on the diagnosis of SAM, the administration of ß-blockers (esmolol) was decided and resulted in hemodynamic stabilization within minutes.
References
- Sherrid MV, Balaram S, Kim B, Axel L, Swistel DG. The Mitral Valve in Obstructive Hypertrophic Cardiomyopathy: A Test in Context. J Am Coll Cardiol. 2016; 67: 1846-1858.
- Slama M, Tribouilloy C, Maizel J. Left ventricular outflow tract obstruction in ICU patients. Curr Opin Crit Care. 2016; 22: 260-266.
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