#cardiac conduction

[all-about-that-grayce]

I’m watching a d&d campaign set in a school and AV club came up and I said, what, atrioventricular club?

Someone laugh.

Please.

[healthwithtips]

Ankylosing Spondylitis - Causes, Diagnosis, Treatment, Ongoing care and Clinical pearls

Basics Description Ankylosing spondylitis (AS) is a chronic inflammatory seronegative arthritis affecting mainly the axial skeleton and sacroiliac (SI) joints, but hips and shoulders may also be involved. System(s) affected: Musculoskeletal; Eyes; Cardiac; Neurological; Pulmonary Synonym:... Ankylosing Spondylitis - Causes, Diagnosis, Treatment, Ongoing care and Clinical pearls

[healthwithtips]

Hyperkalemia– Causes, Symptoms, Diagnosis, Treatment and Ongoing care

Hyperkalemia is a common electrolyte disorder with plasma potassium (K) concentration >5.5 mEq/L (>5.0 mmol/L);Hyperkalemia depresses cardiac conduction and can lead to fatal arrhythmias. Hyperkalemia– Causes, Symptoms, Diagnosis, Treatment and Ongoing care

[defibrillated]

" If we want the cardiac muscle cells to contract, we have to excite them (depolarize them).  Where does the signal that starts off this depolarization come from?  Also, you learned that cardiac muscle cells can spread their depolarizations from cell to cell through gap junctions... but although this works pretty well, it doesn't spread the signal fast enough for all the cardiac muscle cells of the atria or of the ventricles to contract in near synchrony.  So, somehow, we have to send the signal that tells these cardiac muscle cells to contract to all the cells of the heart.  The term "cardiac conduction system" refers to the system of electrical signaling that instructs these muscle cells to contract."

  Read more at link.

[defibrillated]

This is a pretty slow gif of cardiac electrical conduction -- I wish it were a bit faster, but I do like that it shows the EKG line at the bottom to correspond.

[defibrillated]

[tymkrs]

Working on the LED Heart: SR, SB, ST

So you guys remember when I said I wanted to revamp the LED Heart thing and make it somewhat usable for actual students to learn rhythms from.  So first I had to know what timing segments to watch out for.

Essentially all rhythms determine what their ECG counterpart looks like - it could be the PR segment lengthening, could be QRS lengthening, could be having multiple PR intervals.  And depending on what you measure on an ECG monitor, you know what's going on electrically in the patient.  In normal sinus rhythm:

P Wave: 80ms

PR Segment: 50-120ms - I'll use 100ms for a PR Interval of 180ms

QRS: 80-120ms - I'll use 100ms

RR Interval: 0.6-1.2s but taking away the 280ms from the PQRS, that leaves us with 720ms assuming a RR of 1second.

Sinus Rhythm Code:

You notice that once you turn the pin 9 on - it goes for the P wave, then the PR segment, then the QRS, then the quasi RR interval (really T-P interval).  So with most of the others, you just adjust accordingly.

Sinus Bradycardia Code:

So with Sinus Bradycardia, there's no difference between PR intervals and QRS times.  It's mostly the T-P interval which is lengthened.  To do this calculation, I decided to make the heart rate 50bpm.  This meant that of 60seconds, 50 beats would go:  60sec / 50 beats = 1.2secs per beat.  So instead of using 1 second to calculate the T-P interval, you use 1.2secs.  (I know this may be belaboring the point but my dad always told me to not skip steps).  So here it's 1200ms - 280ms = 920ms.

Sinus Tachycardia Code:

So same thing with Sinus Tachy as Sinus Brady - there's no real difference except with the T-P interval.  So I calculated what it'd be given a ~110bpm. 

Step 1: 60sec/110 = 0.55sec. 

Step 2: 550ms - 280ms = 270ms

Next rhythms I'll go over: Atrial Fib, Atrial Flutter, SVT

@atdiy/@tymkrs