Hi Siham,
Great to see you back at the Sphere! I find lots to like here. I enjoyed the musical motifs. The heart seeming to range from harp and concerto to awful drumming and metallic noise. In the title, "heart" might refer to the N's own heart, or "heart" might mean "beloved". The more I read this, the more I tend toward reading the former, but I like that that the latter kind of sits in the back ground, and I guess that even on the former reading, the N is in a relationship with her heart that echoes a romantic one -- a life partnership anyway.
I prefer the original S1. With regard to line order, the original L1 makes for a very strong opening line, I think. It grabs my attention. It's new position at the end of the stanza doesn't work so well for me; it seems more of an afterthought.
I also didn't have an issue with the original L1. Your new version of it seems clunky to me, less naturally phrased, though yes, it yields a very regular IP.
I am glad you lost "hand" in the revised S2, though. As I found the image of a (literal) heart with hands a little odd, and that seemed to suggest that the poem was addressed to a person only.
Related to the above, in both versions of S1, I'm a little confused, in terms of the metaphor, as to whose hands play the harp, and who's captivated by it. If the harp is the heart, who's playing it (though I guess maybe God, the universe, the body)? And if the heart has hands ... well, as above ... that seems a little odd.
The imagery/metaphor of S2 seems a lot clearer: the entwined rhythms of N and her heart. The universe passing through.
S2L4 For some reason I want this to be, "As intimate as fingertips and bones". Maybe because it accentuates the 't' alliteration. Maybe because it ends the line on primary stress, which gives more finality to the stanza end, or because "bones" seems more dramatic here, so that it seems better coming second. Against this, possibly, is that this word-order gives you a slanted end-rhyme with "shows". But hey, why not have some irregularity there too
S3 seems the most opaque stanza here, maybe not helped by cultural differences, though I had at least heard of Walter Cronkite and can google. On first reading, S3 seems to bemoan the passing of time, the change in (news) media, radio giving way to TV giving way to ... the noise of Twitter et al and I guess, or to lower standards in news journalism . Though I'm not that sure how that fits the poem, except in relation to ageing perhaps. Change over time. Loss of a golden age? I guess I can see a descent from harmony to discord that fits the musical motifs of the rest of the poem. The heart failing? Maybe.
That said, I like that S3 is there. It adds something concrete to the more abstract/symbolic vibe of the poem, and maybe also something public/shared to the more private feel of this. I wonder if there's scope for more of this somehow? As it stands, the stanza maybe seems a little at odds with the rest of the poem in its concreteness/specificity.
In S4, the pain and awful drumming seems to continue on the metallic noise of the end of S3. I can read this as the heart -- given the drumming. Though then it seems the heart that holds the N in the face of the drumming. Given the TV news reference, I wonder if the drumming relates to war and coming disaster -- death even, and is in some way external to N and her heart, whose partnership seem lead to a transcendence of this pain/drumming/noise. Though possibly it could be that in partnership, the heart's drumming and pain become transcended, becomes enchanted by the ancient lutes of S5. I'm not complaining about finding this ambiguous. I like that I have options here, and that I'm led to reread and ponder.
In S5, I like the word-play of "chamber music". I wonder about music being "ferried though a sound". Isn't music normally transmitted as sound? On a literal level, how else could it be carried? Maybe you're wanting to say it's mere sound (a heart beat) that becomes music? But it sounds like the music is already there, and what it becomes is enchanted by the lutes.
best,
Matt