Help clarifying something on ekg's

Okay I'm driving myself nuts tonight. So far I got that it's a 12 lead with only 10 leads actually attached b/c some are reading different pathways 12 leads = lead 1,2,3,AVR, AVL, AVF, V1,V2,V3,V4,V5,V6

Lead 1 is reading from + L arm to - R arm

Lead 2 is - R arm to + L foot

Lead 3 is - L arm to + L foot

Where I'm getting tripped up is the L arm seems to be able to generate both + and negative depending on what it's reading is that correct? Because originally I'm thinking that the one electrode is either going to be + or - I get that they're bipolar. Or maybe I don't fully and that's what's tripping me up! Then I started thinking that maybe there are 2 electrodes attached one for positive one for negative but that didn't really make sense.

So basically I'm thinking that the electrode placed isn't necessarily capturing the polarity of positive vs negative at that point (I hope that makes sense I went back over definitions of polar, poles etc...ad nauseam) but it captures the impulse travelling whatever points are being analyzed.

Dubin's book is great...but some things he took for granted that some of us that have to work harder at understanding things would just get!

Thanks to anyone that can dumb this down for me or tell me that I'm finally on the right train of thought. Many hours later!
It's funny this question was posted over 10 hours ago and not one reply, had you put up a complaint about nursing you'd have 20 responses by now LOL ! To answer the question, leads I, II, and III (the limb leads) are bipolar you have both + and -

Quote from LelaRNIt's funny this question was posted over 10 hours ago and not one reply, had you put up a complaint about nursing you'd have 20 responses by now LOL ! To answer the question, leads I, II, and III (the limb leads) are bipolar you have both + and -

You really seem to have it...the only thing I would reiterate is that it is because the limb leads are bipolar, that you don't need multiple electrodes on the LA to generate both the - and + charges (and you seem to have already ruled this out). When it's tracing the Lead I View, LA is +. When it's tracing the Lead III View, LA is -. Because the limb leads are bipolar, they can generate both Lead I and Lead III Views at the same time. That is what is "bipolar" about them. Try looking at some pictures of Einthoven's Triangle - it's much easier to look at than to explain. I like this picture (scroll down to the "Cardiac Vector" section): http://noodle.med.yale.edu/~staib/bme355/ecg/prep.htm

Quote from juliaannYou really seem to have it...the only thing I would reiterate is that it is because the limb leads are bipolar, that you don't need multiple electrodes on the LA to generate both the - and + charges (and you seem to have already ruled this out). When it's tracing the Lead I View, LA is +. When it's tracing the Lead III View, LA is -. Because the limb leads are bipolar, they can generate both Lead I and Lead III Views at the same time. That is what is "bipolar" about them. Try looking at some pictures of Einthoven's Triangle - it's much easier to look at than to explain. I like this picture (scroll down to the "Cardiac Vector" section): http://noodle.med.yale.edu/~staib/bme355/ecg/prep.htm

The hardest thing for me was figuring out that you can have multiple Lead Views (Tracings) from 2 Lead Wires attached to electrodes on the skin. We often think of the tracings as an "impulse" that flows in one direction due to polarity, and that's not entirely helpful! It had me a little hung up on why they call it a "12 Lead EKG" when there are only 10 lead wires. To be honest, despite the crap they get, I've found Wikipedia's quick summary rather helpful. Maybe it will help you, too! Check out the "Unipolar vs. bipolar leads" section!Electrocardiography - Wikipedia, the free encyclopedia

Quote from juliaannThe hardest thing for me was figuring out that you can have multiple Lead Views (Tracings) from 2 Lead Wires attached to electrodes on the skin. We often think of the tracings as an "impulse" that flows in one direction due to polarity, and that's not entirely helpful! It had me a little hung up on why they call it a "12 Lead EKG" when there are only 10 lead wires. To be honest, despite the crap they get, I've found Wikipedia's quick summary rather helpful. Maybe it will help you, too! Check out the "Unipolar vs. bipolar leads" section!Electrocardiography - Wikipedia, the free encyclopedia

LeLaRN, I just love your comment. I love Allnurses, but like you said, a technical question hardly gets looked at. A complaint, chance to grouse, gets 100's or responses, LOL. BTW I'm too out of touch with my cardiac nursing to even touch the question. But I'm never too old to grouse a lot!!!!