Abstract 58: Standard Cardiopulmonary Resuscitation Generates a Compression (Narrowing) of the Left Ventricular Outflow Tract in Humans
Objectives: Little is known about how external chest compressions influence cardiac structures during standard CPR in humans. The aim of this study was to investigate the influence of external chest compression on the cardiovascular structures during CPR.
Subjects and methods: Thirty-four patients with non-traumatic cardiac arrest (23 males, mean age: 56 years old) were enrolled. Multi-plane transesophageal echocardiography was performed during standard CPR, and a 135° longitudinal view was chosen to observe the left ventricular outflow tract (LVOT). An area of maximal compression (AMC) was sought, and the degree of the compression at the AMC was calculated from the diameters of the LVOT or the aorta at the maximal compression during compression systole and compression diastole.
Results: The AMC was identified at the aorta above the aortic valve in 20 patients (59%) and at the LVOT in 14 patients (41%). The AMC was located within 2 cm from the aortic valve in 79% of the patients. Compression of the AMC was noted in all patients and the degree of the compression at the AMC was ranged from 19% to 83% (mean: 49±19%). Compared with the patients having the AMC at the aorta, the patients having the AMC at the LVOT had higher calculated stroke volume and larger left ventricular systolic and diastolic areas (44±15 vs 29±16 ml, p=0.047; 14±7 vs 6±3 cm2, p=0.00; 22±10 vs 10±7 cm2, p=0.00).
Conclusion: Standard cardiopulmonary resuscitation generates variable degrees of compression at the outflow tract of the left ventricle including the LVOT or the aortic root. The hemodynamic effects of this phenomenon should be sought.