title: Compression of the left ventricular outflow tract during cardiopulmonary resuscitation.
abstract: OBJECTIVE
  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.
authors.affiliation: Department of Emergency Medicine, Wonju College of Medicine, Institute of Lifelong Health, Yonsei University Wonju, Wonju, Republic of Korea. shwang@yonsei.ac.kr
authors.forename: Sung Oh
authors.initials: SO
authors.lastname: Hwang
authors.forename: Pei Ge
authors.initials: PG
authors.lastname: Zhao
authors.forename: Han Joo
authors.initials: HJ
authors.lastname: Choi
authors.forename: Kyung Hye
authors.initials: KH
authors.lastname: Park
authors.forename: Kyung Chul
authors.initials: KC
authors.lastname: Cha
authors.forename: So Mi
authors.initials: SM
authors.lastname: Park
authors.forename: Sang Chul
authors.initials: SC
authors.lastname: Kim
authors.forename: Hyun
authors.initials: H
authors.lastname: Kim
authors.forename: Kang Hyun
authors.initials: KH
authors.lastname: Lee
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000379:methods* / Q000592:standards; D003326:Coronary Circulation; D017548:Echocardiography, Transesophageal; D005260:Female; D006323:Heart Arrest / Q000000981:diagnostic imaging / Q000628:therapy*; D006352:Heart Ventricles; D006801:Humans; D007091:Image Processing, Computer-Assisted; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013318:Stroke Volume