Sounds like a PVC. These are the probably most common heart rhythm complaint.
Hello~I have had those, they ARE scary. They are normally just another form of either a PAC or PVC, the forceful beat is the heart making up for the one that was dropped as it pushes the blood through the arteries. The current or tiny shock feeling is common, I have it, it is a form of adrenaline rush due to fear. I have had them in my head as well, they are called "head zaps" and are due to anxiety.
Anxiety is awful, and it is a vicious circle, the skips can cause the anxiety, and the anxiety can cause the skips. The more we stress, the worse it becomes and we notice them more because we in tune with every-little-thing that goes on in our body.
The good news is your holter monitor results are good, as are your other tests.
PVC's can cause a cardiac neurosis in a lot of people. I had this myself and was certainly no fun. Really interrupts your life, relationships and ambitions.
When it comes to bloodwork, especially something like a metabolic panel, one thing that is not checked and really, really should be - is magnesium. It scans for potassium (very important), sodium, chloride, CO2, bounded calcium, and enzymes up the yin-yang, yet no magnesium. Magnesium plays very important roles in neurotransmission, and how it plays into the orchestration of ordered electrical impulses in the heart and all other innervated muscles. Has a lot of importance for enzymatic reactions also. Yet they don't commonly check for it.
If all parameters on the blood assay came back normal, what you may want to do is try supplementing magnesium. Try magnesium taurate or glycinate. Oxides don't absorb well in the gut.
PVC's, which is a type of ectopic beat, are nothing to really be concerned over when they occur in isolation. You can go on for years and then get one, and it can simply be from bending over (stimulating your vagus nerve which can cause it) or coughing too hard, sneezing a lot, etc. But, if you never had them before, and yet they're creeping up on you, ask yourself about your diet. What is your diet like? Do you smoke? Do you drink? Do you take any medication? Have you made some lifestyle changes recently? My issues with arrythmias and PVC's took a long time to develop, and it was mostly related to malnutrition. I ate, wasn't anorexic, but ate very nutrient-empty foods. Eating foods high in potassium and taking magnesium solved it.
As for the forceful beats, those are PVC's. Basically, when the ventricle misses a beat (it beats way too early in the cardiac cycle) it kind of overfills with blood, stretching the muscle more so than normal, and whack! You get that thump or thud. Its not the PVC itself you feel, but the after effect. PVC's in isolation (not occurring in a run, multiple skips) are not dangerous. They should still be investigated. But in and of themselves, pose no threat as they don't interfere with cardiac output. They really don't just come and go at random, there is always some form of precipitating factor involved.
Magnesium basically manages the normal orchestra of electrical activity in the heart. So its a central key element in normal cardiac rhythm. Believe it or not, when a patient has a malignant arrythmia such as one called Torsades De Pointes (TdP), one of the protocols they use in the ER or on ambulance is a large infusion of magnesium sulfate given thru an IV line.
It is just as a effective in terminating an arrythmia such as that of lidocaine or amiodarone which are potent anti-arrythmic drugs. Typically they give up to 2,000 mg of mag sulfate, and the arrythmia abates. With low levels of magnesium, the heart gets irritable, and those skipped beats start to occur.
Hope this helps and quells any concerns you may have. Be well.
Every blood test my Dr ever ran or I had in the er always check magnesium levels.
Original poster...Google "sleep apneA pvcs". You will find plenty of studies that discuss the correlation between sleep apnea and ventricular arrhythmias
Just one study example for you to peruse
There's a lot if you google it.