What was meant to said is that taking medications in rotation was less effective than taking the right med for the right infection for a longer period of time.
Most people who self treat have no access to rx meds so they use vet meds. In my experience they work very well.
Worms in the heart, which worm do you mean? Heartworm or another type?

Two years ago we hit and went right past the animal antiparasitic issue. There actually have been discussions for about the last 8 years. For those of us who wanted to live it was a non-issue.

The actual issue is selecting meds that others indicate are safe. There have been people who had issues in their infections, and they chose certain brands.

Lately I was given information that certain sheep additives may not be at all helpful to humans.

While the subject is way beyond most of us one thing is clear, only select things that others indicate are common and have been used. Walk in the footsteps of others when selecting meds.

I have completed both flat and roundworm protocols. My case is extremely complicated, so my infection required many formulations, and high doses of a spectrum of meds. I may be a bad example of typical. I moved into maintenance, and then alternate with intervention for maintaining my infection into remission, decline, and hopefully a cure of the remaining parasites. Cyst infections cause special situations that may require continued dosing (which I currently practice). I also continue to research cyst approaches.

The simple answer to your second question is: I learned, and dosed almost every human compatible antiparasitic med. I currently low dose a few, on a daily basis.

As for your third question: Heart infections can be one of two kinds, 1) inside the heart chamber, and 2) incidental (outside or passed thru).

Dirofilarial (heartworm chamber) infections require a special mix of Invermectin, Doxycycline, and other approaches that prevent death of the Dirofilarial worms in the heart, or promote a rapid kill.

Nematode Lung infections, or pulmonary stress caused by a number of roundworm species, or nematode birth cycle events, can cause heart stress that feels identical to a heart attack. Hyperinfections and high levels of pulmonary infection can cause the blood birth of filariae, or microfilariae, which can cause significant capillary blockage. Meds, strategies, and circulation meds are required, along with filarial hyperinfection intervention, or suppression of birthing, that all leave one susceptible to adverse situations for weeks, until the infection is drawn down.

Rapid Pulse events are not cardiac events, but parasite enzyme toxin events.

It is important to rule out dirofilarial species prior to starting a broader selection of antiparasitic meds.

There are tests.

I myself had extreme heart lung involvement, that was brought down quickly when I realized I was hyperinfected. Hyperinfections require immediate action.

Situational awareness is required when heart involement is present.

I am unfamiliar with any reported cases where Dirofilarial human infections required surgery.