The first question is why zikre qalbi ( with or without the help of pase anfas) ?
The main reasons are two:1) to try and constantly remember Allah (2) to get rid of useless thinking or talking to ourself and instead replace them with zikr.
Both are very important objectives.Sufia through elham or through their experience found that two systems in the body are automatic,one is breathing which never stops in life and second the constant beating of heart.They found that if we,through practice make them as tools for zikr,that zikr will continue non stop and we will achieve the objectives mentioned earlier.They are more or less the same thing as breathing by itself does not and can not do zikr,so the apparent zikr with breathing is also in effect zikr e qalbi,although they are mentioned separately in text books of sulook.So please remove this confusion from your mind,as the objective of continuos zikr is served both ways.
Those who start zikre qalbi,can be of different natures as no two human beings are similar.
1) they can either straightaway learn how to do zikre qalbi by using their power of imagination,such people do not require any further help and with practice their zikre qalbi gets stronger and more easily audible day by day
2) some of them can not perceive it easily and they need help.For such people mashaikh use different tools to help consolidate their zikr,like :
a) by help of a clicking tasbeeh to synchronize their zikr with each click
b) by using simple non clicking tasbeeh to be turned rapidly and synchronize zikr with it
c) by asking them to keep a wall clock in the room and synchronize zikr with each click of the clock
d) by asking them to put the fingers of one hand on the radial pulse of opposite wrist and synchronize zikr with each beat of the pulse.
e) by putting right hand on left side of chest,where at one point the apex beat can be felt and synchronize zikr with it.
f) ask them to do excessive khafi lisani zikr in thousands which ultimately imprints on our imagination and change into zikre qalbi automatically,and then zikre lisani is stopped,while zikre qalbi continues OR
g) synchronize it with each breathing as i told you,this way both pase anfas and zikre qalbi becomes combined,brething acting as a vehicle while qalb synchronize itself with it to do zikr.