Noninvasive evaluation of pulmonary hypertension by quantitative contrast M-mode echocardiography

More on the noninvasive diagnosis of pulmonary hypertension: Doppler echocardiography revisited

“…Interobserver and intraobserver variabilities appear to be on average 9 and 7% respectively [27]. The recovery rate of pulmonary flow velocity curves ranges 81-98%, does not depend on the severity of pulmonary hypertension, and is not decreased in patients with COPD [10,12,[20][21][22][23][24][25][26][27][28]. It is possible to attain a recovery rate of 100% in normal subjects [15].…”

“…Moderately good to excellent correlation coefficients, from 0.65-0.96, between AT alone or correlated for ET, pre-ejection time or heart rate and mean Ppa or PVR or their logarithms have been reported in many studies on patients with pulmonary hypertension of various severities and origins, but standard errors of the estimates have remained relatively high, up to 10 mmHg and sometimes more [10,12,[20][21][22][23][24][25][26][27][28]. Furthermore, acute changes in Ppa induced by exercise, volume loading, oxygen or nifedipine administration, are only loosely correlated to inverse directional changes in AT [29].…”

Pulmonary blood velocity patterns in lamb models of pulmonary vascular impairment

“…Other percentages between 75% and 95% were considered, but none were as effective in predicting pulmonary pressure or resistance. A technique proposed by Zeiher et al [6], which divides the forward systolic flow pulse into three equally spaced intervals, calculates a mean for each interval, and correlates ratios of those means with pulmonary pressure and resistance, was also evaluated, but correlations with pressures and resistances were poor. Correlation values decreased when 90% times were normalized for heart rate, though the differences were not as notable as those related to rise time.…”

“…The need for improved noninvasive diagnostic techniques has prompted investigations of relationships between abnormal pulmonary circulation and pulmonary artery blood velocity patterns that can be observed with pulsed Doppler ultrasound. Features associated with pulmonary hypertension in humans include increased flow reversal [1][2][3][4][5][6], decreased rise time (time from onset of systole to peak velocity) [1,[7][8][9][10][11][12][13][14], and a velocity waveform with a triangular or skewed shape [15], However, none of the techniques derived for estimating pulmonary pressure and flow solely from features of pulmonary velocity waveforms has proved sufficiently reliable to be widely adopted in clinical practice. Suggested reasons for failure include:…”