TRANSESOPHAGEAL ECHOCARDIOGRAPHIC ASSESSMENT OF MITRAL-VALVE POSITIONAND PULMONARY VENOUS FLOW DURING CARDIOPULMONARY-RESUSCITATION IN HUMANS

Citation
Mhm. Ma et al., TRANSESOPHAGEAL ECHOCARDIOGRAPHIC ASSESSMENT OF MITRAL-VALVE POSITIONAND PULMONARY VENOUS FLOW DURING CARDIOPULMONARY-RESUSCITATION IN HUMANS, Circulation, 92(4), 1995, pp. 854-861
Citations number
35
Categorie Soggetti
Cardiac & Cardiovascular System",Hematology
Journal title
ISSN journal
00097322
Volume
92
Issue
4
Year of publication
1995
Pages
854 - 861
Database
ISI
SICI code
0009-7322(1995)92:4<854:TEAOMP>2.0.ZU;2-E
Abstract
Background The mechanisms of blood flow during closed-chest cardiopulm onary resuscitation (CPR) in humans have been debated since the techni que was first described in 1960. Two competing models, the cardiac pum p theory and the thoracic pump theory, have been proposed, and some in vestigators have used mitral valve position during the downstroke of c hest compression to distinguish between them. Previous studies using e ither transthoracic or transesophageal echocardiography have yielded c onflicting results, and there have been few, if any, hemodynamic or ec hocardiographic studies on pulmonary venous flow (PVF) during CPR. Met hods and Results In this study, transesophageal two-dimensional and pu lsed Doppler echocardiography were used to study mitral valve position and flow, together with PVF, in 20 adult patients undergoing manual C PR. In the 17 patients who could be analyzed, the mitral valve closed in 5 patients (group 1) during chest compression but stayed open or op ened further in the remaining 12 patients (group 2). Peak forward mitr al flow occurred during the release phase in group 1 but during the co mpression phase in group 2. During chest compression, PVF occurred in the forward direction (from the pulmonary vein to the left atrium) in 8 of the group 2 patients (group 2a) and in the backward direction (fr om the left atrium to the pulmonary vein) in all group 1 patients and the remaining 4 patients in group 2 (group 2b). The downtime (time fro m collapse to CPR) was significantly shorter (P<.05) for those in grou p 1 (7.0+/-4.4 minutes) than in groups 2a (19.8+/-7.7 minutes) and 2b (17.8+/-6.8 minutes). Conclusions Transesophageal echocardiography per formed during manual CPR in humans disclosed three different patterns of mitral valve position and PVF during chest compression. The presenc e of an opened mitral valve with forward mitral flow and backward pulm onary venous flow during chest compression in a small number of subjec ts underscores this heterogeneity in blood flow and suggests the possi ble existence of a ''left atrium pump'' in addition to the currently k nown ''left ventricle pump'' and ''chest pump'' mechanisms.