Mechanical dysfunction in the border zone of an ovine model of left ventricular aneurysm
| Autor: | Michael J. Moulton, Michael K. Pasque, Douglas S. Fishman, James L. Cox, David M. Amsterdam, Stephen W. Downing, Lawrence L. Creswell, Barna A. Szabó |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Pulmonary and Respiratory Medicine
Muscle Fibers Skeletal Diastole Ventricular Dysfunction Left Aneurysm medicine Animals Heart Aneurysm Systole Sheep medicine.diagnostic_test Cardiac cycle business.industry Myocardium Stroke Volume Magnetic resonance imaging Anatomy medicine.disease Magnetic Resonance Imaging Myocardial Contraction Disease Models Animal Left Ventricular Aneurysm medicine.anatomical_structure Surgery Border zone Cardiology and Cardiovascular Medicine business Mathematics Artery |
| Zdroj: | The Annals of Thoracic Surgery. 60:986-998 |
| ISSN: | 0003-4975 |
| DOI: | 10.1016/0003-4975(95)00521-l |
| Popis: | Background. The pathophysiology of regional mechanical dysfunction in the border zone (BZ) region of left ventricular aneurysm was studied in an ovine model using magnetic resonance imaging tissue-tagging and regional deformation analysis. Methods. Transmural infarcts were created in adult Dorsett sheep (n = 8) by ligation of the distal homonymous coronary artery and were allowed to mature into left ventricular aneurysms for 8 to 12 weeks. Animals were imaged subsequently using double oblique magnetic resonance imaging with radiofrequency tissue tagging. Short axis slices were selected for analysis that included predominantly the septal component of the aneurysm as well as adjacent BZ regions in the anterior and posterior ventricular walls. Dark grid patterns of magnetic presaturations were placed on the myocardium and tracked as they deformed during the diastolic, isovolumic systolic, and systolic ejection phases of the cardiac cycle. Regional ventricular wall strains were calculated in BZ regions and regions remote from the aneurysm and compared with strains measured in corresponding regions from normal control sheep (n = 6). Results. Diastolic midwall circumferential strains (fiber extensions) were relatively preserved, but abnormal circumferential lengthening strains were observed in the BZ regions during isovolumic systole. Peak circumferential strains ranged from 0.04 to 0.07 in the BZ regions but averaged −0.05 in the normal hearts ( p = 0.002 for the anterior BZ and p = 0.001 for the posterior BZ). Midwall end-systolic fiber strains were depressed in the anterior BZ (−0.03 to −0.09 for the BZ versus −0.11 for the normal heart, p p = 0.19). Conclusions. Our data support the theory that the stretching of BZ fibers during isovolumic systole contributed to a reduction in fiber shortening during systolic ejection and thus reduced the overall contribution of these fibers to forward ventricular output. |
| Databáze: | OpenAIRE |
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