Author + information
- Received March 12, 1985
- Revision received August 14, 1985
- Accepted September 3, 1985
- Published online January 1, 1986.
- ↵aAddress for reprints: Bodh I. Jugdutt, MBChB, 2C243 Walter MacKenzie Health Sciences Center, Division of Cardiology, University of Alberta, Edmonton, Alberta, T6G 2R7 Canada.
Temporal changes in infarct collagen and left ventricular topography during healing after myocardial infarction were studied in 132 dogs with coronary artery ligation: 8 sham dogs and 13 with no infarction (controls) and 111 with infarction (3 at 1 day, 54 at 2 days, 25 at 7 days, 3 at 2 weeks, 9 at 4 weeks and 17 at 6 weeks). Myocardial hydroxyproline (a marker of collagen) was measured by spectrophotometry and pathologic infarct size, arteriographic occluded bed size and topography by computerized planimetry of weighed left ventricular rings. Over 6 weeks, hydroxyproline was unchanged in normal regions (average 4.20 mg/g dry weight) but increased progressively between 7 days and 6 weeks (9.94 versus 55.55 mg/g, p < 0.001) in infarct zones. Progressive infarct contraction occurred over 6 weeks, with infarct size at 6 weeks being 40% less than at 2 days (9.7 versus 16.3% of the left ventricle, p < 0.001), although total infarct hydroxyproline was directly related to infarct size at each time period (r = 0.73 to 0.81, p ≤ 0.05).
Significant (p ≤ 0.05) left ventricular topographic changes in infarct hearts compared with control hearts included: 1) increase in cavity area (5.0 versus 3.9 cm2), endocardial circumference (8.8 versus 7.4 cm) and expansion index (infarct/normal endocardial segment length, 1.21 versus 1.02) by 7 days; and 2) decrease in thinning ratio (infarct/normal wall thickness, 0.71 versus 0.98) by 6 weeks. Also, compared with 2 day infarcts, by 6 weeks infarct area was decreased (1.8 versus 3.4 cm2) and the noninfarcted segment length increased (6.9 versus 5.4 cm). Changes in hydroxyproline and topography were similar for anterior (n = 54) and posterior (n = 57) infarcts.
Thus, healing in canine infarcts is associated with cavity dilation and infarct expansion within 7 days followed by infarct contraction and thinning by 6 weeks, whereas collagen increases between 7 days and 6 weeks. Collagen deposition in expanded and thinned infarct segments explains the permanent regional shape distortion associated with ventricular aneurysms.
↵1 Dr. Jugdutt is a recipient of a Senior Clinical Investigator Award from the Canadian Heart Foundation, Ottawa, Ontario.
This study was supported in part by grants from the Medical Research Council of Canada, Ottawa, Ontario.
- Received March 12, 1985.
- Revision received August 14, 1985.
- Accepted September 3, 1985.
- American College of Cardiology Foundation