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[Re-evaluation of determinants of the cardiothoracic ratio using two-dimensional echocardiography]
T Mikami1, T Kudo, M Hashimoto
1Department of Cardiovascular Medicine, Hokkaido University School of Medicine, Sapporo.
Insights
Cardiothoracic ratio (CTR) on chest X-rays is strongly linked to left atrial size. This finding helps understand cardiac chamber enlargement impacts on chest imaging.
Area of Science:
- Cardiology
- Radiology
- Medical Imaging
Context:
- Cardiothoracic ratio (CTR) is a common measurement on chest radiographs.
- Assessing cardiac chamber size is crucial for diagnosing heart conditions.
- Two-dimensional echocardiography (2DE) provides detailed cardiac chamber measurements.
Purpose:
- To investigate the correlation between cardiothoracic ratios (CTR) and the dimensions of the four cardiac chambers.
- To determine which cardiac chamber's enlargement most significantly influences the CTR.
Summary:
- The study correlated CTR from chest radiographs with cardiac chamber sizes measured by 2DE in 118 individuals.
- A strong correlation was found between CTR and the left atrial (LA) long diameter (r=0.84).
- Atrial chamber sizes showed higher correlation with CTR than ventricular sizes, with LA enlargement significantly impacting CTR.
Impact:
- Findings suggest that CTR is highly sensitive to left atrial enlargement.
- This research can improve the interpretation of cardiothoracic ratios in clinical practice.
- Understanding CTR's relationship with specific chambers aids in diagnosing and monitoring cardiac conditions.
Abstract:
To evaluate the correlation of cardiothoracic ratios (CTR) on chest radiography with the sizes of the four cardiac chambers, we studied 41 normal persons and 77 cardiac patients using two-dimensional echocardiography (2DE). The transverse cardiac diameter and the CTR were ascertained from their chest radiographs. Using 2DE, each cardiac chamber was evaluated three-dimensionally, by measuring the short and long diameters of each left (LV) and right ventricle (RV), the diameter of the RV outflow, the anteroposterior, transverse, and long diameters of each left (LA) and right atrium (RA). These values were corrected using the square root of the body surface area. The correlation coefficient for the CTR was greatest in the long diameter of the LA (r = 0.84), and was greater in the atrial diameters (r greater than or equal to 0.71) than in the other diameters except for the transverse diameter of the RA (r less than or equal to 0.51). The contribution of each cardiac chamber to the transverse cardiac diameter was evaluated in 34 patients with cardiac enlargement by a method using the null hypothesis, which we originally designed. Consequently, the contribution of the LV to the CTR was definitely proven in two patients, that of RV in two, that of LA in 15 and that of RA in nine. These results indicated that the CTR is strongly influenced by enlargement of the LA.