Doppler Evaluation of Changing Cardiac Dynamics during Cheyne-Stokes Respiration: Results
Mean transmitral velocity and peak early velocity are significantly higher at the end of hyperpnea as compared to the end of apnea. An increase in peak late transmitral filling velocity (A wave) occurs between these two phases. Consequently, the E/A ratio shows a significant decrease from end-hyperpnea to end-apnea (Fig 1). Similarly directed quantitative changes were found with respect to the E integral, A integral, and the ratio.
Cyclic changes in the left ventricular (LV) outflow velocity were also present (Table 2). The measured peak LV outflow velocity is greater at the end of the hyperpneic phase than at the end of the apneic phase as is the velocity-time integral. The cyclic and concomitant changes in the transmitral left ventricular inflow and left ventricular outflow are illustrated in Fig 2. this
There were no significant differences in heart rate, ejection time, or diastolic filling time between the two phases of the Cheyne-Stokes respiration cycle.
The changes in intracardiac velocities in the patient with a cerebrovascular accident and normal LV function paralleled the changes seen in the rest of the study group who were all in heart failure.
In this study, we have found alterations of transmitral blood flow velocity, as well as changes of left ventricular outflow velocity, during the varying respiratory phases of Cheyne-Stokes cycle breathing. Analysis of the transmitral left ventricular inflow Doppler pattern provides useful information about the filling properties of the left ventricle. The normal Doppler pattern of transmitral flow is that of a rapid increase in flow velocity early in diastole, followed by a later smaller increase in velocity with atrial systole. Certain variations of this pattern correlate well with angiographic and radionuclide indices of diastolic function. Numerous Doppler variables have been examined to assess diastolic function.
Table 2—Left Ventricular Outflow Flow Parameters (n=10)
|End Hyp||End Ap||p value|
|Peak LVO, cm/s||68.1±22.1||52.8 ±16.7||<0.001|
|Mean LVO, cm/s||40.7 ±12.7||32.0 ±10.0||<0.001|
|VTI||10.2 ±4.3||7.3 ±2.9||<0.001|
|HR per min||80.1 ±8.3||78.8 ±10.0||NS|
|LVET, s||0.24 ±0.04||0.22 ±0.03||NS|
Figure 1. The transmitral filling profile recorded continuously throughout a portion of the Cheyne-Stokes cycle. On the left of the display, which is at the end of the hyperpneic phase, the early filling velocity (E) is higher than the late filling velocity (A). The E/A ratio is 1.8. Through the apneic phase, in the middle part of the trace, the E velocity diminishes and the A velocity increases. At the end of the apneic phase, on the right of the trace, the E/A ratio is reduced to 0.8.
Figure 2. Changing inflow and outflow profile velocities are displayed. In the inflow section (left), the transmitral profile is shown at the end of hyperpnea (HYP) and at the end of apnea (AP). The difference in early filling (£) and late filling (A) velocities between the phases is apparent. In the outflow section (right), sampled in the ascending aorta, the decline in peak velocity (V max) from the end of the hyperpneic to the end of the apneic phase is noted.