[Dobutamine stress causes left ventricular outflow tract obstruction]

Area of Science:

• Cardiology
• Echocardiography
• Hemodynamics

Background:

• Hypotension during dobutamine stress echocardiography (DSE) has both ischemic and non-ischemic origins.
• The role of sigmoid interventricular septum, a common finding in the elderly, in causing DSE-induced hypotension is not well-established.

Purpose of the Study:

• To investigate whether sigmoid interventricular septum contributes to hypotension during DSE.
• To explore the potential mechanism of dynamic left ventricular outflow tract obstruction in this context.

Main Methods:

• A cohort of 12 patients (mean age 67 years) with sigmoid interventricular septum underwent DSE.
• Patients were divided into a hypotensive response group (Group H) and a non-hypotensive group (Group N).
• Echocardiographic parameters, including left ventricular dimensions, outflow velocity, and aorto-septal angles, were measured at baseline and peak dobutamine dose.

Main Results:

• Seven patients (58%) developed hypotension (Group H) during DSE.
• Group H exhibited smaller end-systolic dimensions, increased fractional shortening, and higher outflow velocities and pressure gradients at peak dobutamine.
• Systolic anterior motion of the mitral valve with septal contact, indicative of dynamic left ventricular outflow tract obstruction, occurred in 86% of Group H patients.

Conclusions:

• Sigmoid interventricular septum can lead to hypotension during DSE, primarily through the induction of dynamic left ventricular outflow tract obstruction.
• This phenomenon can occur even in the absence of regional myocardial ischemia or wall motion abnormalities.
• The findings highlight the importance of recognizing sigmoid septum as a potential cause of hemodynamic compromise during DSE.