tokens: Subsequent addition of phenylephrine infusion , sufficient to re - elevate mean arterial pressure to 106 + / - 4 mm Hg ( P less than 0 . 001 ) for 30 minutes , increased left ventricular filling pressure to 17 + / - 2 mm Hg ( P less than 0 . 05 ) and also significantly increased sigmaST ( P less than 0 . 05 ) .