We report a case of a 17-year-old patient referred to our outpatient Doppler Department due to clinical suspicion of liver cirrhosis. The patient presented with non-specific symptoms, such as malaise, pain in the right subcostal region, peripheral oedema. Until then, diagnostic imaging, including echocardiography was inconclusive. We performed the Doppler sonography of the portal system, which revealed normal diameter of the portal vein with abnormal, phasic and markedly pulsatile waveform. Hepatic veins distention with pathological reverse flow during systole was reported. Additionally, inferior vena cava was dilated and remained unchanged through the respiratory cycle. Basing on the above image a heart disease, which had not been taken into differential diagnosis before, was suggested. The following echocardiography, together with computed tomography, enabled a diagnosis of constrictive pericarditis. Successful pericardiotomy was performed. Such a complicated diagnostics happened to demonstrate an uncommon example of the use of portal vein waveform in making the proper cardiologic diagnosis.