ECG 8. The ECG above is from a 67 years-old woman with a diagnosis of alcoholic dilated cardiomyopathy and
paroxysmal atrial flutter. She was admitted to Cardiology department because of repeated pre-syncope.
She was on carvidilol, quinapril, spironolactone, bumetanide, atorvastatin and
digoxin therapy.
Her ECG on admission is seen above. This is a junctional escape rhythm in the setting of digitalis intoxication.
Sinus bradycardia, sinus arrest and sinus Wenckebach conduction are not uncommon in digitalis toxicity.
The reason why the sinus node is inhibited in this patient is due to digitalis intoxication with extreme sinus bradycardia/SA
block combined with overdrive suppression by the retrograde P waves. The slow junctional escape rhythm conducts
retrogradely - suggested by the superior P wave axis - with a long ventriculoatrial (VA) interval. Besides slowing the antegrade
atrioventricular (AV) conduction, it has also been shown that digitalis slows/blocks the retrograde fast pathway conduction.
The reason why the retrograde impulse conducts via the retrograde slow pathway - suggested by the long VA interval - is
probably due to retrograde fast pathway block in the setting of digitalis intoxication or due to the absence of retrograde fast
pathway conduction. The impulse then re-enters the ventricle via the fast pathway and initiates the so-called
ventricular echo beat (Figure 8). The RP interval is longer than the PR interval, signifying that the impulse is travelling
in a retrograde fashion via the slow pathway and then antegradely down to the ventricle via the fast pathway.


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The ECG above has been used with the permission of Netherlands Heart Journal.

Click here to read the relevant article by Alzand B.S.N.




Figure 8. Above is the ladder diagram explanining the mechanism of the group beating in ECG 8.
An AV nodal escape rhythm is travelling in a retrograde fashion to the atrium via the slow pathway
and then antegradely to the ventricle (
echo beat) via the fast pathway.

The ECG above has been used with the permission of Netherlands Heart Journal.

Click here to read the relevant article by Alzand B.S.N.





ECG 9a. The ECG above belongs to a 60 years-old man with acute anterior myocardial infarction.
It was recorded 60 minutes before coronary angiography. The rhythm is sinus.

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ECG 9b. The same patient was immediately transferred to the coronary angiography laboratory where his infarct-related LAD
artery was successfully opened by a stent. The above single-channel rhythm tracing was recorded by the defibrillator
during the procedure. After the revascularization, first
accelerated idioventricular rhythm appeared, which rapidly
turned to
sinus rhythm. A P wave is seen in the last ventricular beat of the accelerated idioventricular rhythm (evidence
of AV dissociation
).

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ECG 9c. Ten seconds after the ECG 9b,
his rhythm was sinus (left side of the above tracing). The recording was then stopped.
Two minutes later, the recording was started again when
accelerated junctional rhythm emerged.
Now the QRS complexes lack preceding P waves. Instead,
the retrograde negative P waves are seen in the ST segment.
This rhythm also subsided quickly and sinus rhythm appeared again.

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ECG 10a. The above ECG is from a 78 years-old man with coronary artery disease.
It was recorded immediately before triple coronary bypass surgery + mitral ring annuloplasty.
The rhythm is normal.

Dr. Sinan Altan Kocaman has donated the above ECG to our website.

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ECG 10b. The above ECG is belongs to the same patient. It was recorded 5 days after the cardiac operation.
The patient was under positive inotrope therapy during this time.
What is your diagnosis?

Dr. Sinan Altan Kocaman has donated the above ECG to our website.

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ECG 10c. There are no P waves preceding the QRS complexes.
Small deflections (waves) following the QRS complexes are difficult to notice at first glance. .
Sometimes P waves may follow QRS complexes during nodal rhythm (as is above).
The patient was under positive inotrope therapy when this ECG was being recorded.
The diagnosis is nodal rhythm.

Dr. Sinan Altan Kocaman has donated the above ECG to our website.

Click here for a more detailed ECG




ECG 10d. The above ECG was also recorded on 5th postoperative day.
P waves following QRS complexes are difficult to notice at first glance.
The diagnosis is nodal rhythm.

Dr. Sinan Altan Kocaman has donated the above ECG to our website.

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ECG 10e. The above ECG was recorded after cessation of positive inotrope therapy.
P waves following QRS complexes are more clear now.
The diagnosis is nodal rhythm.

Dr. Sinan Altan Kocaman has donated the above ECG to our website.

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ECG 11a. The ECG above belongs to an 84 years-old woman with chronic renal failure, hyperkalemia (6.9 mmol/L)
and coronary artery disease. This ECG is recorded at a standard
calibration of 10 mm/mV.

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ECG 11b. This ECG belongs to the same woman.
It was recorded 30 seconds after the ECG 11a, but at a
calibration of 20 mm/mV.
Now
P waves are easily discernible. The rhythm is junctional (nodal) rhythm.
Junctional beats do not have preceding P waves.
Some
atrial extrasystoles with P waves are also seen.

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