Is It the Nicotine Itself That Constricts Blood Vessels?

Nicotine does constrict blood vessels, and, therefore could decrease the blood supply to the skin creating issues with healing. This is true whether the nicotine is coming from cigarettes, e-cigs devices, gum, patch and so on. Not every smoker will have problems healing, but there is certainly an increase in risk. I recommend that patients stop using nicotine for 3-4 weeks prior to facelift and often plan for treatments with hyperbaric oxygen after surgery to improve healing (if needed). Given the fact that this is a completely elective procedure, I do not recommend surgery on active smokers/nicotine users. I don't believe the risk is worth it - it's better to plan and postpone the surgery until you're ready.

The answer is very simple. Yes, nicotine does constrict skin blood vessels and causes a much higher rate of complications for cosmetic surgery procedures. Narrowing of the blood vessels means less blood flow and then oxygen to the cells. This is needed to heal from surgery.  All surgeries are usually more likely to have complications in smokers especially lung complications but also depending on the type of surgery if tissue is rearranged, these flaps can also be at risk for dying or undergoing necrosis.  The risk is simply not worth it.  
Any vaping, gum, patches or imitation ecigarettes that contain nicotine can have the same effect even though they may not contain all of the other harmful chemicals.  While some people can use these products to wean off cigarettes, they are still things that you should stop before surgery to avoid complications.  I typically recommend my patients be off of all nicotine products for 3-4 weeks before  and at least 4-6 weeks after (but preferably for life) to allow optimal surgical healing.  
I would recommend that you see a board-certified plastic surgeon in your area that is a member of both ASPS & ASAPS and go over your concerns with them.
I hope this helps answer your question.  If it does, please take a moment to up vote this answer on the “respond” button on the top right.  

Yes you are correct it is the actual nicotine itself that causes vasoconstriction which can lead to poor healing after any surgery, and in facelift can be disastrous as the think skin flaps are at risk of necrosis (dying from lack of blood flow).  The imitation or e cigarettes that contain nicotine may be useful tool for quitting smoking but are not a healthy alternative to smoking.  Nicotine without the smoke can still cause heart disease, vascular disease, and make you at higher risk for some cancers.  If I have a patient who is a smoker, I would recommend they quit smoking at least 2 weeks prior and stay away from any nicotine products for at least a month after surgery (but hopefully for the rest of their life as well).  You may find some surgeons that say performing a facelift in the deep plane may be less risky for smokers.  But if you are planning to invest in appearance by having a facelift, wouldn't you also consider investing in your health and longevity by quitting smoking and enjoying the results of your facelift for longer?