Damping Index of Doppler Hepatic Vein Waveform to Assess the Severity of Portal Hypertension and Response to Propranolol in Liver Cirrhosis: A Prospective Nonrandomized Study

Moon Young Kim; Soon Koo Baik; Dong Hun Park; Dae Wook Lim; Jae Woo Kim; Hyun Soo Kim; Sang Ok Kwon; Young Ju Kim; Sei Jin Chang; Samuel S.Lee

Disclosures

Liver International. 2007;27(8):1103-1110. 

In This Article

Discussion

Portal hypertension causes serious complications such as variceal bleeding, and is responsible for significant mortality in patients with cirrhosis. Therefore, precise assessment of the severity of portal hypertension is necessary for the management of cirrhosis. HVPG measurement has been accepted as the gold standard for assessing the severity of portal hypertension.[1,6,16] However, this method is limited clinically because of its invasiveness. Doppler ultrasonography is so non-invasive that many investigators have attempted to demonstrate its usefulness in assessment of portal hypertension.[1,2,3,4,5]

Healthy subjects usually show a triphasic HV waveform that is ascribed to variations in the central venous pressure because of the cardiac cycle.[7,8] In cirrhosis, the presence of abnormal biphasic or monophasic HV waveforms has been incontrovertibly demonstrated by a number of studies.[10,11,12,13,14,15] Furthermore, previous work has shown that the monophasic waveform is correlated with higher Child-Pugh scores and decreased survival rates.[19] In our previous study, we demonstrated a direct correlation between abnormalities in HV Doppler waveforms and HVPG, i.e. with increasing HVPG, the Doppler HV waveform tended to be flattened. In addition, the monophasic waveform was associated with severe portal hypertension (HVPG>15 mmHg) with relatively high sensitivity and specificity.[6] In other words, flattening of the Doppler HV waveform suggests a high likelihood of severe portal hypertension. However, although the above qualitative analysis of the HV waveform is superior to quantitative measurement in terms of technical ease and reproducibility, qualitative methods have severe limitations in evaluating responses to drug therapy. For instance, even though propranolol may improve an abnormal baseline HV waveform, it could remain classified as biphasic at both baseline and after propranolol treatment. However, when using the quantitative DI, a change of HV waveform can be more precisely measured as a decrease in DI from 0.61 to 0.33, concomitant with a decrease in HVPG from 18 to 11 mmHg (Figure 4 for example). Thus, for evaluation of response to portal hypotensive drugs, a quantitative measurement such as DI would be vastly preferable. Furthermore, in the present study, a DI cut-off value of 0.6 permitted the diagnosis of severe portal hypertension with a sensitivity of 75.9% and specificity of 81.8%. Hence, this is another advantage of this quantitative measurement in determining the severity of portal hypertension as well as the response to portal hypotensive drug treatment.

In our previous study, we showed that a change in HV Doppler waveform is closely correlated with that of HVPG following administration of terlipressin, a synthetic long-acting analogue of the vasopressin. Hence we suggested that the evaluation of Doppler HV waveforms could be a supplementary tool to gauge response to portal hypotensive drugs. Propranolol, a non-selective ß-blocker, has been shown to decrease the risk of variceal bleeding through a reduction in portal inflow and portal pressure.[17,18] In this study, we evaluated the changes in both DI and HVPG before and after chronic propranolol administration in a subgroup of the study population. The change in DI significantly correlated with that of HVPG following propranolol administration. Hence, evaluation of the HV DI might be a useful supplemental method for assessing the therapeutic response to portal hypotensive drugs when HVPG examination is not available.

Our study has some limitations. First, DI measurement was performed by a single individual (S. K. B.). This may be problematic when performing subjective data analysis. However, the 93% concordance of waveform subtypes when assessed by another coauthor reassured us that this method of classification and measurement is reproducible by different observers. Second, the patients in the propranolol substudy were not a true random subset of the overall study group. In this regard, however, their clinical characteristics did not significantly differ from those of the larger group. Although the measurement of the HV DI has been used previously,[15] to our knowledge, this is the first demonstration of its validity and usefulness in quantitating the degree of portal hypertension. If the present results can be confirmed in further studies, this completely non-invasive method might prove to be a readily available and popular alternative to invasive methods such as measurement of HVPG in patients with cirrhosis and portal hypertension.


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