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Effects of cardiomyoplasty on right ventricular filling during volume loading
Y Toyoda1, M Okada, M A Kashem
1Department of Surgery, Kobe University School of Medicine, Japan.
Insights
Cardiomyoplasty (CMP) may impair right ventricular diastolic filling due to external constraints. This study found CMP reduced right ventricular compliance, limiting diastolic filling during volume loading.
Area of Science:
- Cardiovascular Surgery
- Cardiac Physiology
Background:
- The impact of cardiomyoplasty (CMP) on ventricular systolic function is established, but its effects on diastolic function, particularly right ventricular filling, remain unclear.
- Pericardial influences are more significant in the right ventricle, suggesting CMP's external constraint could impair right ventricular diastolic filling.
Purpose of the Study:
- To investigate the effects of cardiomyoplasty (CMP) on right ventricular diastolic function and filling.
- To evaluate hemodynamic changes in the right ventricle following CMP, especially under volume loading conditions.
Main Methods:
- The study involved 14 beagles, with 7 undergoing left posterior cardiomyoplasty (CMP) and 7 serving as controls (sham operation with pericardiotomy).
- Hemodynamic parameters were assessed via heart catheterization before and after rapid volume loading (10 mg/kg albumin solution over 5 minutes).
Main Results:
- In the CMP group, right atrial pressure and right ventricular end-diastolic pressure significantly increased post-CMP, unlike in controls.
- Volume loading did not significantly alter right ventricular end-diastolic volume or stroke volume in the CMP group.
- Controls showed significant increases in right ventricular end-diastolic volume and stroke volume after volume loading.
Conclusions:
- Cardiomyoplasty may reduce right ventricular compliance.
- The external constraint imposed by CMP appears to restrict right ventricular diastolic filling, particularly during rapid volume expansion.
Background:
Although cardiomyoplasty (CMP) is thought to improve ventricular systolic function, its effects on ventricular diastolic function are not clear. Especially the effects on right ventricular diastolic filling have not been fully investigated. Because pericardial influences are more pronounced in the right ventricle than in the left ventricle, CMP with its external constraint may substantially impair right ventricular diastolic filling.
Methods:
Fourteen purebred adult beagles were used in this study. Seven underwent left posterior CMP, and 7 underwent a sham operation with a pericardiotomy and served as controls. Four weeks later, the hemodynamic effects of CMP were evaluated by heart catheterization before and after volume loading (central venous infusion of 10 mg/kg of 4.5% albumin solution for 5 minutes).
Results:
In the CMP group, mean right atrial pressure and right ventricular end-diastolic pressure increased significantly from 3.1 +/- 1.2 mm Hg to 6.1 +/- 2.0 mm Hg (p < 0.001) and from 4.0 +/- 1.8 mm Hg to 9.6 +/- 2.5 mm Hg (p < 0.001), respectively. Volume loading in the control group did not significantly increase either variable. Right ventricular end-diastolic volume and stroke volume did not change significantly (from 53 +/- 9.3 mL to 60 +/- 9.0 mL and from 20 +/- 2.3 mL to 21 +/- 3.2 mL, respectively) in the CMP group. In the control group, however, right ventricular end-diastolic volume and stroke volume increased significantly from 45 +/- 7.7 mL to 63 +/- 14 mL (p < 0.05) and from 18 +/- 4.3 mL to 22 +/- 4.2 mL (p < 0.05), respectively.
Conclusions:
These results suggest that CMP may reduce right ventricular compliance and restrict right ventricular diastolic filling in response to rapid volume loading because of its external constraint.