Compression of the left ventricular outflow tract during cardiopulmonary resuscitation.

Objectives: This prospective observational study was performed to investigate if the hand position used for external chest compressions is in an optimal position for compressing the ventricles during standard cardiopulmonary resuscitation (CPR).

Methods: Transesophageal echocardiography (TEE) was performed during standard CPR in 34 patients with nontraumatic cardiac arrest (24 males, mean +/- standard deviation [SD] age = 56 +/- 12 years). On the recorded image of TEE, an area of maximal compression (AMC) was identified, and the degree of compression at the AMC and the left ventricular stroke volume was calculated.

Results: A significant narrowing of the left ventricular outflow tract (LVOT) or the aorta was noted in all patients, with the degree of compression at the AMC ranging from 19% to 83% (mean +/- SD = 49 +/- 19%). The AMC was found at the aorta in 20 patients (59%) and at the LVOT in 14 patients (41%). A significant narrowing of more than 50% of the diameter at the end of the relaxation phase occurred in 15 patients (44%). On linear regression, the left ventricular stroke volume was correlated with the location of the AMC (R(2) = 0.165, p = 0.017).

Conclusions: The outflow of the left ventricle is affected during standard CPR, resulting in varying degrees of narrowing in the LVOT and/or the aortic root.