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Regional ventricular systolic abnormalities caused by a rudimentary chamber in patients with univentricular hearts
1Department of Pediatrics, Osaka University Medical School, Suita City, Japan.
Insights
Regional wall motion abnormalities in univentricular hearts are linked to asynchronous motion, potentially caused by the rudimentary chamber. This asynchronous motion may contribute to ventricular diastolic dysfunction.
Area of Science:
- Cardiology
- Medical Imaging
- Physiology
Background:
- Regional wall motion abnormalities are frequent in univentricular hearts.
- The underlying mechanisms and hemodynamic implications remain incompletely understood.
Purpose of the Study:
- To investigate the causes of regional wall motion abnormalities.
- To analyze the relationship between these abnormalities and hemodynamics in univentricular hearts.
Main Methods:
- Tagged cine magnetic resonance imaging (MRI) to assess regional systolic motion.
- Calculation of percent regional shortening fraction and an asynchrony index.
- Hemodynamic parameters obtained via cardiac catheterization.
Main Results:
- Segments near the rudimentary chamber showed significantly reduced regional shortening fraction.
- Patients exhibited a markedly higher asynchrony index compared to controls.
- The asynchrony index correlated with rudimentary chamber size, volume ratios, and end-diastolic pressure.
Conclusions:
- The rudimentary chamber appears to be a significant factor in asynchronous regional motion.
- Asynchronous motion may contribute to diastolic dysfunction in univentricular hearts.
Abstract:
Previous studies have demonstrated that regional wall motion abnormalities are common in univentricular hearts; however, the mechanism of this abnormality and its relation to hemodynamics remain unclear. The aim of this study was to document and analyze the etiology of regional wall motion abnormality and its relation to hemodynamics in univentricular hearts. Sixteen patients (age 11+/-6 years) were examined. A tagged cine magnetic resonance imaging method that superimposes "tags" on myocardium was used to assess regional systolic motion. The tags were traced from end-diastole to end-systole, and the percent regional shortening fraction was calculated as the shortening ratio. The tags were positioned on 6 segments. Normal ranges for wall motion were established from 10 normal volunteers. An asynchrony index was calculated as the SD divided by the mean regional shortening fraction to quantify asynchronous regional motion. Hemodynamic parameters were also obtained by cardiac catheterization. In patients, regional shortening fraction was significantly lower in segments adjacent to the rudimentary chamber compared with normal values in both circumferential and longitudinal directions (p <0.05 and p <0.01, respectively). The asynchrony index was much greater in patients than in controls (62+/-25 vs 27+/-10, p <0.01). The index correlated with rudimentary chamber volume and the rudimentary/main chamber volume ratio (r = 0.58, r = 0.79, respectively). Furthermore, the index correlated with end-diastolic pressure (r = 0.82). The rudimentary chamber may play an important role in causing asynchronous regional motion, and this motion may contribute to ventricular diastolic dysfunction.