Why is it when a heart starts beating regularly again in the ER they call it "normal sinus rythm"? I thought sinus had to do with your nose, mouth, eyes, etc. I've been thinking maybe I wasn't paying enough attention, but during 'Peace of the Wild Things' when Gabe opened up the chest and was instructing Malucci, he specifically pointed to the patient's heart.

-- AmyE (roamyn@aol.com), April 04, 2000

Answers

"Sinus rhythm" does have to do with the beating of the heart. I'm not in the medical profession, but I've had six open heart surgeries, so I've tried to familiarize myself with medical terminology. I think that on an EKG (test of the heart beat) there is a P-Q-R-S-T curve. I think the "S" stands for sinus. The heart starts beating at the point labeled "P" and completes the cycle at the point labeled "T". I could be wrong, but I believe that "normal sinus" refers to the point when all points on the chart are following a "healthy" pattern.

-- Carin (cdenisehaze@usa.net), April 05, 2000.

A sinus rhythm is so-named because the contraction of the heart muscle (and hence what you see on an EKG) begins with the depolarization of the sinus node, somewhere in the apex of the right atrium. This is the normal state of affairs, and so we call it normal sinus rhythm.

Now, for the reason why I love having the root password around here..

Normal sinus rhyhtm looks like this:

If you don't know anything about electrophysiology, you can be forgiven for having a blank look on your face right now. I'm throwing that strip from Lead II in a patient with a normal sinus rhythm in strictly for illustration. Note that the trace is fairly symmetrical and regular; this is a good sign. Astute observers with good eyesight might note that the rate is almost a perfect 60 beats per minute. (Sorry, I didn't make it very easy to count the boxes -- trade off when I resized. Trust me, it's ~60.)

Carin, you're quite right that the components of a beat are called PQRST, but it has nothing to do with the name of each part of the heartbeat. It has to do with how the waveform breaks down when graphed out:

The P wave represents the firing of the sinus node and subsequent depolarization (and contraction) of the atria, and the QRS complex represents the beginning of ventricular depolarization. If you look at the waveform, you'll notice that there are three distinct lines. If the first of these lines heads downwards (relative to the resting position, the flat line throughout the strip), it's a Q wave; the first upward wave is the R wave. The second line south of the resting position is the S wave. It's possible to have RSR, RS, and QR complexes depending on what's going on in the heart.

The T wave marks the repolarization of the ventricles. There isn't really much to say about the T wave in this context except that T wave inversion is often a hallmark of myocardial ischemia, or a heart attack.

And there you have it. The eleven-cent introduction to cardiac electrophysiology. Hope someone found that useful.

-- Mike Sugimoto (phloem@fumbling.com), April 05, 2000.

I was wondering what the heart does when a person says they felt a "palpitation". Is the palpitation caused by an irregular heart beat? and does this indicate a problem with the heart? Thanks :)

-- Emma (empatto@hotmail.com), April 06, 2000.

palpitation is the kind of feeling you have when you "hear" and feel perfectly each lub-dub.It happens ussualy when you have taquicardia? (i donīt know the name in english-sorry)

-- Ines (inesuca00@terra.es), March 04, 2001.

No answer - sorry - I am not a medical person. However, fyi - have after almost 3 years suffered from dizy spells and chronic pain in left shoulder blade, shoulder, arm and feeling so unwell almost like panic attacks. Horrible! After lots of investigations with ENT specialists, chiropractioners, sport injury massagers, acupuncture, even spiritual healers - all to no avail. The NHS kindly passed me from ENT to Cardio who have done a very thorough check on me for every possible thing over almost a year period. The notes are astounding - X-rays show nothing - all tests show nothing - I read my own notes casually and they seem to be of opinion I have a trapped nerve. This I have said many months back to no avail. They still insist on their own tests to no avail. I did notice a 24 hour ECG showing 2 ABP (or something to that effect) but always refferring to sinus rythm.... no knowledge of this at all. a 48 hour ECG 6 months later was completely negative. Do the nerves in arm/shoulder/wrist/elbow have such a big effect on diagnosing a nerve problem or is the heart the most obvious issue to take up and examine - surely the overall outlook of an active working patient would show them that this is not the issue after such a long period inbetween! If I was going to have a heart attack, it would have happened well in between these three years lapsed! Any comments because I am at a loss - but all respect to NHS - are doing a wonderful MOT on me but feel so guilty as should be dedicating their time to the people who in my opinion really need it.

Ta for any help!

-- Jill Pickering Gonzalez (Picapicture@btopenworld.com), June 25, 2002.