 earli effect digitali central hemodynam normal subject intraven administr lanatosid 7 normal subject effect 1 earli reduct heart rate 2 transient reduct cardiac output 3 increas stroke volum initi accompani rise end-diastol volum unchang systol rate empti increas end-diastol volum lengthen diastol fill period systol empti rate increas ventricular volum decreas suggest inotrop drug 4 increas pulmonari blood volum parallel increas stroke volum suggest passiv relat variabl 