Related Experiment Videos
[Hypertrophy or hyperplasia of myocytes in heart hypertrophy?]
S Grajek1, S Paradowski, M Zajac
1Pracowni Patomorfologii Serca I Kliniki Kardiologii.
Insights
Cardiac muscle growth involves cell size increase (hypertrophy) or number proliferation (hyperplasia). This study found significantly more myocytes in heavier hearts, suggesting hyperplasia contributes to cardiac enlargement.
Area of Science:
- Cardiovascular Pathology
- Cell Biology
- Histology
Context:
- The existence of myocyte hyperplasia in cardiac muscle pathology is a long-standing controversy.
- Understanding cardiac growth mechanisms is crucial for treating heart conditions.
Purpose:
- To investigate whether cardiac myocyte hyperplasia occurs during cardiac hypertrophy.
- To analyze the relationship between myocyte number and left ventricular (LV) weight.
Summary:
- Histometric analysis of 103 hearts revealed that myocyte number significantly increases in LV weights above 250g (5.53 x 10^9 vs 4.31 x 10^9 myocytes).
- While most histometric parameters correlated with LV weight up to 350g, myocyte number showed a significant increase in heavier hearts.
- Coronary artery diameter was the only evaluated factor that significantly influenced LV weight.
Impact:
- Provides evidence supporting the occurrence of myocyte hyperplasia in cardiac hypertrophy.
- Suggests that myocyte proliferation contributes to pathological cardiac enlargement.
- Informs understanding of irreversible myocardial damage and the challenges in reversing cardiac hypertrophy.
Abstract:
One of the most controversial problem in cardiac muscle pathology is the existence of myocyte hyperplasia. The term hypertrophy indicates an increase in size of the individual muscle cells without changing their total number, whereas in hyperplasia there occurs proliferation of the myocyte. This fundamental question of the character of cardiac growth remains unresolved in spite of the wide attention it has received. Contemporary views concerning the cardiac muscle hyperplasia are presented. From clinical point of view the problem is significant for two reasons. The loss of the ability of muscle cells to proliferate is responsible for the irreversible myocardial destruction after injury. From another point of view, if the increase of the heart muscle is maintained, although a complete remission of cardiac hypertrophy becomes impossible. In 103 hearts with various forms of cardiac muscle hypertrophy the following parameters were estimated: diameter, length, volume, density and number of myocytes, as well as the density of nuclei of myocytes. The values of all histometric parameters correlated well with the LV weight up to 350 g. In heavier hearts these parameters were approximately at the same magnitude. The number of myocytes was significantly higher in hearts with LV weight above 250 g than in hearts below 250 g: 5.53 x 10(9) vs 4.31 x 10(9), p < 0.001. The influence of coronary artery diameters, degree of atherosclerosis, weight and percent of fibrous tissue and age on LV weight were evaluated as well. From these parameters only coronary artery diameters significantly influenced on LV weight.(ABSTRACT TRUNCATED AT 250 WORDS)