First, you're correct, premature heartbeats, be they ventricular or atrial in origin, are harmless. We all have them sometimes, and some of us are acutely aware of them, while others never feel a single one (I must say I envy those people). They may come and go or become more frequent on occasion, then go away for no apparent reason. The list of benign causes of these annoying sensations is at least as long as your arm. Among items on that list would be any number of medications. One of those can be Amitriptyline, just FYI.
The "kick in the chest" sensation is frequently reported, usually with some alarm. Part of the reason this happens -- for some people -- is that the timing of the premature ventricular contraction (PVC -- these are usually the ones that are sometimes felt as a literal kick) can make it seem "light" of touch or a "kick." The more violent-seeming ones usually have happened just at the moment when the tricuspid valve is closed, which does, in fact, take one's breath away for a moment. It's harmless, but that sensation just adds to the disturbing quality of the event. When the valve is closed the blood can't be pushed out to the lungs and causes both that "stolen breath" sensation, but often also what are called cannon A-waves in the neck, as the blood then regurgitates up the jugulars, causing a sense of momentary fullness in the neck.
All this can be really disturbing if the subject happens to experience a brief (or not-so-brief) run of ventricular bigemeny, where every other beat is, for a while, a PVC. If this isn't troubling enough (unless one has become used to it), if the pattern occurs so that each early beat happens when the tricuspid valve is closed (easy for this to happen, since the beat isn't happening when it's "supposed" to), the result can be a sense of shortness of breath and something bordering on chest pain or pressure -- until the pattern shifts or stops what it's doing. It's still harmless, but it is essentially like getting that "kick" in the chest about 30 times in a row, sometimes even more (some people have bigemeny as their "normal" rhythm, but these rarely notice it). I only mention this in passing, since anyone who has a spell of frequent or even occasional PVCs can also have a run of bigemeny and might feel quite alarmed if this sensation were new.
Premature atrial beats (which arise, as one might assume, in the atria instead of the ventricles) are sometimes perceived as less noxious, because the atria (the upper chambers of the heart) are smaller. The beat still gets conducted to the ventricles, but the sensation is often has less "punch" to it. These,however, may cause more of a "fluttery" sensation, which is also disturbing if it is new. Bear in mind, also, that while these sensations are benign and common, one doesn't notice them until one day one does notice them. Once they've been noticed it's a little more difficult to get past that, but if they get frequent enough most people do begin to ignore them.
Hopefully this will quiet down soon. Some people have this on a daily basis, but just remember, no matter how weird they feel, they are benign. About all we can do to minimize them is try to relax, cut out caffeine (or at least accept that caffeine will cause them or make them more frequent), and if they become relentless and produce a lot of anxiety, they can be reduced in frequency and force by use of a beta blocker (a medication that slows the heart rate and reduces the force of the heart's contractions). This is something available when the problem just becomes intolerable.
I hope this is helpful to you. Good luck with this.
John Kenyon, EMT, CCT
Non-invasive cardiology tech, Emergency and Critical Care technician, Critical Incident Stress Mgmt. specialist