Experimental study: using the continuous wave Doppler spectrum technique to detect left atrial pressure

BACKGROUND: This study sought to investigate the accuracy of estimating left atrial pressure (LAP) using the continuous wave Doppler spectrum of mitral regurgitation. METHODS: Dog models of left atrial hypertension with mitral regurgitation were established with disposable biopsy forceps and the injection of melamine formaldehyde resin microsphere suspension. A total of 40 models of left atrial hypertension with different hemodynamic statuses were established by injecting either esmolol or dobutamine in which the spectrums of mitral regurgitation were clear and the regurgitation velocity exceeded 3.5 m/s. The continuous wave Doppler spectrums of mitral regurgitation were recorded and analyzed to estimate left atrial pressure (LAP(ECHO)). The mean left atrial pressure (LAP(C-MEAN)), the isovolumic diastolic left atrial pressure (LAP(C-IVRT)), the maximum left atrial pressure (LAP(C-MAX)), and the minimum left atrial pressure (LAP(C-MIN)) were also measured using the catheter method in the same cardiac cycle. RESULTS: The LAP(ECHO) (mean ± standard deviation; 11.77±4.36 mmHg) was correlated with the LAP(C-MEAN) (11.51±4.77 mmHg; r=0.887, P=0.000), but the difference was not statistically significant (P=0.459). The LAP(ECHO) was correlated with the LAP(C-IVRT) (12.16±4.72 mmHg; r=0.883, P=0.000), but the difference was not statistically significant (P=0.271). There was a correlation between the LAP(C- MEAN) and the LAP(C-IVRT) (r=0.987, P=0.000), and the difference was statistically significant (P=0.000). CONCLUSIONS: This study suggests that the ultrasound evaluation of LAP correlates well with LAP measured using the gold standard catheter method, and is a simple, convenient, non-invasive method to quantitatively estimate LAP. This method is promising, but further large-scale animal experiments and clinical studies need to be conducted.