Beatlas

Follow an ECG from ion channels to the surface waveform. Membrane currents, action potential, conduction and ECG move on one timeline. 39 conditions, offline, no ads.

Don't memorize the ECG. Watch it being made.

Beatlas is an educational simulator that traces why an ECG waveform looks the way it does, starting at the ion channel. Membrane currents, action potential phases 0-4, excitation spreading through the conduction system, and the waveform recorded at the body surface all move together on a single shared timeline. Drop the playback speed to 0.05x and you can follow excitation travel from septum to apex to free wall during a single QRS.

One timeline, four layers

• Cardiac conduction map - membrane potential by region shown in color, repolarization progress shown at the border
• Membrane and ion channels - relative magnitudes of I(Na), I(CaL), I(to), I(K), I(K1), I(f) in real time
• Action potential - phases 0-4 aligned to the same time axis as the ECG below
• ECG - primary and secondary leads shown together, with P/QRS/ST/T/U segments color-coded
• Every current carries a one-line note: what it is, which phase it builds, which drugs target it

39 conditions

• Normal sinus rhythm (rate 45-150)
• Electrolytes - hyper/hypokalemia, hyper/hypocalcemia, hyper/hypomagnesemia, hyper/hypophosphatemia
• Bradycardia and junctional - sinus arrest, sinus arrest with junctional escape, SA block, junctional rhythm
• Conduction blocks - 1st degree, 2nd degree Mobitz I and II, 3rd degree AV block, RBBB, LBBB
• Ischemia and infarction - subendocardial ischemia, anterior STEMI (LAD), inferior STEMI (RCA)
• Arrhythmias - atrial fibrillation, atrial flutter, PVC bigeminy, ventricular tachycardia, ventricular fibrillation, torsades de pointes, WPW, PSVT, AVNRT, AVRT
• Drugs - Vaughan-Williams classes 1a/1b/1c/2/3/4, digoxin

How drugs act on ion channels Pick a drug and a block marker appears on the channel it targets, the current bar actually drops, and the waveform changes to match.

• Class 1a (quinidine) - blocks I(Na) and I(Kr) together, widening QRS and prolonging QT
• Class 1c (flecainide) - blocks I(Na) strongly, widening QRS only
• Class 3 (amiodarone) - blocks I(Kr) only, prolonging QT only Put those three side by side, raise the sliders, and the distinguishing features become obvious on their own.
• Class 2 beta blockers and class 4 calcium blockers act on nodal tissue, producing bradycardia and PR prolongation.
• Digoxin inhibits the Na/K pump, producing scooped ST depression and a shortened QT.

Most conditions have a severity slider. Raise serum K from 5.5 to 9.0 and watch the order in which T waves peak, P waves disappear, and QRS widens.

Automatic measurement The app measures the waveform it generated and reports the numbers.

• Heart rate, PR, QRS duration, QT, QTc
• ST deviation measured against the PR segment and shown per lead
• When measurement is inappropriate, as with a wide QRS, it says so explicitly rather than reporting a number (the same principle behind using Sgarbossa criteria in bundle branch block)

Controls

• Tap a region of the heart to switch to that region's action potential and ion currents
• Drag the ECG to scrub to any moment
• Playback 0.05x-2x, amplitude gain, horizontal scale
• Full-screen ECG - rotate to landscape for a wider strip

Who it is for Medical students, residents, nursing and paramedic students, and anyone who teaches ECG. For everyone who has to explain why phase 2 is a plateau, or why the T wave points the same way as the QRS.

Korean and English One button in the header switches everything, including all four explanation blocks for each of the 39 conditions.

Fully offline There is no server. No account, no login, no network traffic. It collects no personal information, and there are no ads and no in-app purchases.

This is an educational simulator, not a medical device. The waveforms shown are models that reproduce the typical findings of each condition from parameters. They are not real patient recordings. It must not be used for diagnosis or treatment. Actual diagnosis must be based on a real 12-lead ECG and clinical findings.