Cardiac electrophysiology fellow with an interest in the familial, words, and the history of electrophysiology.
Unfortunately the tachycardia could not be induced in the laboratory. Here are the baseline recordings – 12 lead ECG, and His bundle electrogram.
The diagnosis was made however with pacing manoeuvres in sinus rhythm.
Considering the differential diagnosis mentioned in the comments on the post previous, what pacing manoeuvres could be used in sinus rhythm to make a diagnosis?
22 yo Male with a history of palpitations for 2 years.
What abnormalities do you note on the baseline ECG?
What is the differential diagnosis of the tachycardia?
EGMs will follow.
Thanks to Eraldo de Moraes for contributing this case! (If any other readers have a case I'm more than happy to put it up – it only needs to be interesting).
This is a not uncommon phenomenon in a common arrhythmia.
Figure 1: Initiation with double extra stimuli. Figure 2: A spontaneous PVC during tachycardia.
A previous post may help: http://epfellow.posterous.com/peel-back-phenomenon-easy-ep-1
Not always ventricular tachycardia. For rounds:
Sometimes easiest to appreciate the effect of preexcitation by examining its absence. Left anterolateral accessory pathway; ablated around 2-3 o'clock on the mitral annulus.
I have never received a clear answer as to what – which in my opinion must include insight into mechanism – a far-field signal is. Why should a potential from far away appear on an electrode overlying a small patch of tissue? Here is my qualitative understanding; for a quantitative understanding – see Bioelectricity by Plonsey (a difficult read).
In the figure, notice the sharp atrial signals (local activation) in the coronary sinus electrograms, and the smoother ventricular signals (far-field); also the atrial signals are of greater amplitude than the ventricular though the ventricular muscle bulk is much greater. The RV catheter, however, is showing very sharp (local activation) electrograms of high amplitude.
This rhythm is irregularly irregular, though not markedly so. Does the degree of irregularity matter?
At 1:56 am this 49 yo man was woken by the frantic nurse and resident. Are you ok? He was. [Don't look at picture 2 unless you want to know the answer].
After four years of basic science research I'm back on the wards for my clinical fellowship. I suspect my posts will be quite different.
Interesting ShockWave (it is alive!) demonstration of a neat trick for quickly determining the frontal axis of a 12 lead ECG. It does encourage the conflation of unipolar and bipolar leads (apples and oranges), which is one of those things that is reasonable in most circumstances, but should not be done when a truly accurate measurement of the frontal axis is required. However, all in all, a nice presentation. (via EMS12lead.com)
English inflicting serious psychological harm on the Aussies now. Test cricket is the cardiac electrophysiology of sports: once understood, few things are better. Interventional cardiology is a little more like 20/20...
"Nodoventricular (NV) bypass tracts were described pathologically in 1937 by Mahaim and Benatt. Later, fibres connecting the AV node and the right bundle branch - nodo-fascicular (NF) - were recognised. Now it is known that the majority of clinically apparent bypass tracts thought to be NV or NF, are actually slowly conducting atrio-ventricular or atrio-fascicular pathways. True NV or NF tracts are extremely rare."
"George the Second, who survived the Prince near ten years, died at last not less suddenly than his son, though at the advanced age of Seventy-seven; a period attained by no Sovereign in modern History, except Louis the Fourteenth. A rupture in some of the vessels, or in the Membrane of the Heart, carried him off in a few minutes. During his whole life, but particularly for a number of years before his decease, he had been subject to such constant palpitations about the region of the Heart, especially after Dinner, that he always took off his cloaths, and reposed himself for an hour in bed, of an afternoon."
Historical memoirs of my own time: Volume 1 - Sir Nathaniel William Wraxall
Received my copy of Pacemakers and Implantable Cardioverter Defibrillators: An Expert's Manual today. Looks good. Nice size for 'knee reading' when I'm looking after the little one. Can't say the study has been very productive tonight...
"Quantitative analysis of culture using millions of digitized books"
Jean-Baptiste Michel et al., 2010 Science
You may have seen this article in Science. The authors investigated cultural trends by examining the frequency of certain words or phrases in the vast library of scanned google books. This allowed them to provide "insights about fields as diverse as lexicography, the evolution of grammar, collective memory, the adoption of technology, the pursuit of fame, censorship, and historical epidemiology".
As a simple example of what this means - using the google landing page, and typing in 'enemy', gives this graph:
Note the three peaks: ~1860 corresponding to the American Civil War (and perhaps other conflicts), and 2 smaller peaks around WWI and WWII. Of course, much more complex searches may be made. I thought it might be interesting to examine some trends in cardiac electrophysiology. As a first step, let's try 'electrophysiology':
Whoops; looks like we've already peaked.
We can also see the trends in language use within electrophysiology. For instance, if you read the old textbooks you may come across 'auricular fibrillation' - an old way of referring to 'atrial fibrillation'. Hmmm, I wonder when we started using the new term...
And with the publication of the landmark paper from Haïssaguerre in 1998, an effective treatment for the condition was developed.
But our focus on atrial fibrillation seems to have impacted on other areas in electrophysiology:
To be fair, I think that may have a little more to do with CAST; the preliminary results of that study landed in 1989 and were the first nail in the 'anti-arrhythmic' coffin.
Evidently, we don't like it if we're not sure what to do about it.
I'm sure that many more interesting searches could be made in regard to electrophysiology and other fields of study.
