## Abstract

Previous observations (Garcia et al. 1998; Sohn et al. 1997; Nagueh et al. 1997) indicate that mitral annulus velocity may be viewed as a 'load-independent' index of filling and that wedge pressure is linearly related to the transmitral flow velocity (V_{E)} to mitral annulus velocity (V_{MA)} ratio (V_{E}/V_{MA)} measured at maximum velocity. In healthy subjects, the mean value observed for [V_{E}]_{max}/[V_{MA}]_{max} was 1:0.23 ≅ 4. No prior physiologic or physical explanation for the basis of, or for the magnitude of, the ratio has been proposed. We propose a physiologic, model-based, quantitative explanation for these observations and test our simplified model's prediction in an invasive (n = 30) and noninvasive (n = 34) test groups of subjects. The simplified geometric model is based on the known constant volume (within a few percentage points) attribute of the four-chambered heart. Accordingly, left-atrial and left-ventricular volumes reciprocate so that their sum is constant throughout the cardiac cycle. The model predicts that: 1. the ratio (V_{E}/V_{MA)} is a constant ≅3 in healthy hearts; and 2. V_{E}/V_{MA} should be linearly proportional to left ventricular end-diastolic pressure (LVEDP). Model prediction was tested using V_{E} and V_{MA} echocardiographic data from 34 subjects (noninvasive group), and simultaneous echocardiographic and high-fidelity hemodynamic (LVEDP) data in 30 subjects (invasive group). Excellent agreement was observed between model prediction and observed data. For the noninvasive (healthy) group, [V_{E}]_{max}/[V_{MA}]_{max} = 4.20 ± 1.11. For the invasive group, [V_{E}]_{max}/[V_{MA}]_{max} was observed to be linearly related to LVEDP, [V_{E}]_{max}/[V_{MA}]_{max} = 0.19 (LVEDP) + 1.54, r = 0.92. Hence, [V_{E}]_{max}/[V_{MA}]_{max} is a legitimate flow-derived index of diastolic function because it is a derivable consequence of the heart's constant-volume pump attribute. (E-mail: sjk@howdy.wustl.edu)

Original language | English |
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Pages (from-to) | 499-507 |

Number of pages | 9 |

Journal | Ultrasound in Medicine and Biology |

Volume | 27 |

Issue number | 4 |

DOIs | |

State | Published - Apr 2001 |

## Keywords

- Diastole
- Echocardiography
- Law of the heart
- Physiologic modeling