Document Detail


Chronic septal infarction confers right ventricular protection during mechanical left ventricular unloading.
MedLine Citation:
PMID:  19577075     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: Right ventricular failure manifests in 25% of left ventricular assist device recipients because of ventricular coupling mechanism disruption. Septal ischemia accentuates this process, but the effect of septal infarction has not been elucidated. Right ventricular response to incremental left ventricular unloading was studied in sheep with septal infarction. METHODS: Septal infarction was induced in 6 sheep using ethanol delivery into the main septal perforating artery. Six shams avoided ethanol. Load-independent and in-series right ventricular response to incremental (0%-100%) left ventricular unloading was measured 4 weeks later. Dimensions of whole heart, wall thickness, and chamber volumes were obtained using sonomicrometers. Selective perfusion with triphenyltetrazolium quantified septal damage. RESULTS: Right ventricular preload-recruitable-stroke-work, contractility, and ejection fraction were lower at 75% and 100% left ventricular unloading in sham compared with infarcted animals (75%: 26.3 +/- 3.4, 0.70 +/- 0.15, and 23.9 +/- 4.6 vs 37 +/- 2.6 erg *10;3, 0.99 +/- 0.18 mm Hg/mL, and 35.5% +/- 3.4%, all P < . 01, 100%: 24.8 +/- 4.5, 0.67 +/- 0.14, and 23.8 +/- 5.8 vs 36.0 +/- 4.6 erg *10;3, 0.90 +/- 0.09 mm Hg/mL, and 32.7% +/- 11.0%, all P < . 01). Central venous pressure was higher at 75% and 100% unloading in sham compared with infarcted animals (75%: 8.6 +/- 1.0 vs 4.5 +/- 1.0, 100%: 12.4 +/- 0.8 vs 3.4 +/- 1.0 mm Hg, all P < . 01). Right ventricular cardiac output was less in shams with 100% unloading (1.2 +/- 0.2 L/min vs 2.1 +/- 0.3 L/min, P < . 01). End-diastolic and end-systolic right ventricular short-axis dimension at 75% and 100% unloading was greater in sham compared with infarcted animals (75%: 34.4 +/- 5.5 mm and 29.1 +/- 5.5 mm vs 25.6 +/- 4.7 mm and 20.5 +/- 4.0 mm; 100%: 37.6 +/- 6.6 mm and 29.9 +/- 5.9 mm vs 25.5 +/- 3.9 mm and 21.1 +/- 3.8 mm, all P < .01). Prolonged diastolic relaxation (Tau) in infarcted animals was normalized with 75% and 100% unloading. CONCLUSION: High-level (>or=75%) left ventricular unloading causes right ventricular dilatation and compromised function. Chronic septal damage, however, confers protection by preserving right ventricular dimensions.
Authors:
James Mau; Stuart Menzie; Yifei Huang; Michael Ward; Stephen Hunyor
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The Journal of thoracic and cardiovascular surgery     Volume:  138     ISSN:  1097-685X     ISO Abbreviation:  J. Thorac. Cardiovasc. Surg.     Publication Date:  2009 Jul 
Date Detail:
Created Date:  2009-07-06     Completed Date:  2009-07-28     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0376343     Medline TA:  J Thorac Cardiovasc Surg     Country:  United States    
Other Details:
Languages:  eng     Pagination:  172-8     Citation Subset:  AIM; IM    
Affiliation:
Cardiac Technology Centre, Kolling Institute, St Leonards, Australia. jmau@med.usyd.edu.au
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MeSH Terms
Descriptor/Qualifier:
Animals
Heart / physiopathology
Heart Septum
Heart-Assist Devices*
Hemodynamics*
Myocardial Infarction / physiopathology*
Sheep
Ventricular Function, Left
Ventricular Function, Right*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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