Document Detail

Detecting myocardial ischaemia using miniature ultrasonic transducers--a feasibility study in a porcine model.
MedLine Citation:
PMID:  19581103     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Detection of myocardial ischaemia during and after cardiac surgery remains a challenge. Echocardiography is more sensitive in ischaemia detection than echocardiography (ECG) and haemodynamic monitoring, but demands repeated examinations for monitoring over time. We have developed and validated an ultrasonic system that permits continuous real-time assessment of myocardial ischaemia using miniature epicardial ultrasound transducers.
METHODS: In an open-chest porcine model (n=8), prototype ultrasound transducers were fixed on the epicardium in the left anterior descending and circumflex coronary artery supply regions, providing continuous measurement of transmural myocardial velocities. Peak systolic velocity and post-systolic velocity were recorded simultaneously with ECG, left ventricular pressure and arterial pressure. Two-dimensional (2D) echocardiographic strain was used as a reference. Global changes were induced by infusing fluid, epinephrine, nitroprusside and esmolol. Regional changes were induced by occluding the left anterior descending coronary artery (LAD). Subsequent LAD stenosis was performed in a subgroup, with flow reduction to 50% of baseline level and further to occlusion.
RESULTS: Systolic velocity in the LAD region decreased during LAD occlusion (0.9+/-0.1 to 0.1+/-0.1 cm s(-1), P<0.01), whereas post-systolic velocity increased (0.3+/-0.1 to 2.3+/-0.1 cm s(-1), P<0.01). No changes occurred in the circumflex coronary artery (CX) region. Severe ischaemia was confirmed by reduction in 2D echocardiography strain calculations. Changes in myocardial velocities assessed by miniature transducer during ischaemia differed from changes during all global interventions. Significant reduction in systolic velocity occurred at 50% LAD flow (0.9+/-0.1 to 0.5+/-0.1 cm s(-1), P=0.02) with further decrease on following occlusion (0.0+/-0.0 cm s(-1), P<0.01). Post-systolic velocity increased both from baseline to 50% LAD flow, and further to occlusion.
CONCLUSION: The epicardial transducers provided continuous assessment of regional myocardial function and detected ischaemia with high sensitivity and specificity. Further development of this system may provide a useful tool for myocardial monitoring during and after cardiac surgery.
Andreas Espinoza; Per Steinar Halvorsen; Lars Hoff; Helge Skulstad; Erik Fosse; Halfdan Ihlen; Thor Edvardsen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2009-07-05
Journal Detail:
Title:  European journal of cardio-thoracic surgery : official journal of the European Association for Cardio-thoracic Surgery     Volume:  37     ISSN:  1873-734X     ISO Abbreviation:  Eur J Cardiothorac Surg     Publication Date:  2010 Jan 
Date Detail:
Created Date:  2010-02-03     Completed Date:  2011-01-11     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8804069     Medline TA:  Eur J Cardiothorac Surg     Country:  Germany    
Other Details:
Languages:  eng     Pagination:  119-26     Citation Subset:  IM    
Copyright Information:
Copyright 2009 European Association for Cardio-Thoracic Surgery. Published by Elsevier B.V. All rights reserved.
The Interventional Centre, Rikshospitalet University Hospital, Oslo, Norway.
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MeSH Terms
Cardiac Surgical Procedures / adverse effects
Coronary Stenosis / physiopathology,  ultrasonography
Disease Models, Animal
Epidemiologic Methods
Myocardial Ischemia / etiology,  physiopathology,  ultrasonography*
Signal Processing, Computer-Assisted
Sus scrofa

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