Evaluation of electrocardiogram parameters and heart rate variability during blood pressure elevation by phenylephrine in cirrhotic rats

Cirrhotic cardiomyopathy is a myocardial disease that may go undetected in the early stages due to peripheral vasodilatation. The aim of the study was to evaluate the electrocardiogram (ECG) and heart rate variability (HRV) after raising blood pressure by phenylephrine injection in rats with liver cirrhosis. Twenty male Sprague-Dawley rats were divided into the Sham and common bile duct ligation (CBDL) groups. After 44 days, animals were anesthetized and the right femoral artery and vein catheterized. After a steady-state period, a bolus injection of phenylephrine (PHE, 10 µg/µl/IV, baroreflex maneuver) was followed by a slow injection of PHE (100 µg/ml/5min/IV, sustained maneuver). Rapid and slow injections of PHE resulted in a greater increase in MAP and a weaker bradycardia response in the CBDL group than in the sham group. ECG analysis showed increased QT, QTc, JT, and T peak to T end in the CBDL group, which did not change after PHE injection. On the other hand, the parasympathetic indices of the HF band and RMSSD, and the sympathetic index of the LF band were lower in the CBDL group than in the sham group after PHE injections. ECG data indicated prolonged ventricular depolarization and repolarization, independent of the level of blood pressure in cirrhosis, whereas the parasympathetic and sympathetic components of HRV decreased regardless of the duration of the elevated blood pressure. We suggest HRV analysis can provide a useful approach in evaluating cardiac dysfunction during increasing blood pressure in cirrhosis.