Contrary to classic teaching regarding the utility of neck fullness and witnessed neck pulsations in making an accurate diagnosis of typical AVNRT,1, 12
neither historical point was useful in distinguishing typical AVNRT from AF or AFL. However, amongst those with SVT, while a sensation of neck fullness demonstrated little utility, witnessed neck pulsations were highly associated with typical AVNRT in both univariate and multivariate analyses, demonstrating a high specificity and a moderately high positive predictive value.
The theoretical basis of both neck fullness and neck pulsations in typical AVNRT arises from the fact that the arrhythmia is, essentially by definition, an “A on V” tachycardia, or one where the atria and ventricles are simultaneously (or nearly simultaneously) contracting.13
Hemodynamic assessments during AVNRT support this theory, revealing a single AV wave and a higher degree of flow reversal on right atrial angiography.6
In contrast, in short RP tachycardias (such as in AVRT) or long RP tachycardias, such as in sinus tachycardia or the majority of atrial tachycardias, the sequential contraction of the ventricles followed by the atria (or visa versa) should not result in the atria contracting against closed atrioventricular valves. Finally, neither AF nor AFL are thought to generate enough of an atrial contraction to cause either symptoms of neck fullness or cannon A waves.
Gursoy et al. queried 244 consecutive patients with a history of palpitations regarding any symptoms of rapid and/or regular pounding in the neck (i.e., neck fullness) during palpitations.6
These symptoms were then correlated with the results of the electrophysiology study when an arrhythmia was observed or induced or when the patient felt palpitations. In all but 4 of 54 patients with AVNRT, patients reported “neck pounding,” whereas none of the other 190 patients with other arrhythmias reported this symptom. This study has become a widely cited paper associating neck fullness and the diagnosis of typical AVNRT.1, 12
From this report, prominent text books have referred to neck fullness or “pounding” as a helpful symptom in making the diagnosis of AVNRT,8, 9
with one stating that the symptom is “practically pathognomonic” of AVNRT.10
In fact however, previous studies have never examined the utility of neck fullness when including subjects with AF or AFL. Because the management of AF/AFL patients is significantly different from that of AVNRT (and as the management of typical AVNRT is not largely different from the management of other SVTs such as AVRT or atrial tachycardia), the argument can be made that the AVNRT versus AF/AFL distinction is in fact the most crucial one. Unfortunately, it appears that this symptom has no value in making this distinction.
While cannon A waves or witnessed neck pulsations (sometimes called the “frog sign”5
) during tachycardia have also been purported to be particularly helpful in making the diagnosis of typical AVNRT,1, 8, 9
this has, to our knowledge, never been formally studied. Although this historical point was again not helpful in excluding AF or AFL, it was helpful in distinguishing typical AVNRT from other types of SVT. Although the immediate management in clinic may not differ as a result of this finding, counseling the patient regarding the details, rates of success, and risks of invasive curative ablation procedures may in fact be influenced.13
For example, whereas ablation of AVRT may often involve a left sided approach (such as via a transseptal puncture), typical AVNRT can be addressed from the right sided circulation in the majority of cases. Similarly, the success of typical AVNRT ablation is likely higher than that of other arrhythmias such as atrial tachycardia.13
The reasons for the discrepancy between the previous literature and our findings are not clear. It may be that the textbooks have been guided primarily by clinical anecdote, which often relies on extreme and perhaps more obvious cases without a more objective measurement of the number of cases that do not fit the paradigm or the denominator of the total cases without a given sign or symptom. In addition, although the study by Gursoy et al. addressed this topic (as above),6
the main point of that paper involved understanding the hemodynamic mechanism of symptoms in AVNRT rather than a blinded, rigorous assessment of the test characteristics of the symptoms, without inclusion of patients with AF or AFL.
This study has several limitations. First, the neck pulsations were not directly observed, but rather reported as witnessed by the patient. While this might take away from the accuracy in determining whether or not obvious cannon A waves were indeed present, the point of interest in clinical practice is in fact the historical report of witnessed neck pulsations. In other words, the point is to test the sensitivity and specificity of the particular question (not necessarily the phenomenon itself) that can be asked in the clinic or emergency department when the patient is in sinus rhythm. Second, although the interviewer was blinded to the diagnosis amongst all of those with SVT, it was not practical to blind the interviewer in some cases where the patient presented in AF or AFL and a cardiac monitor was clearly visible. However, given the traditional teaching regarding the questions in regards to typical AVNRT, one would have expected a lack of blinding in interviewing the AF/AFL subjects to bias the test characteristics in favor of typical AVNRT. Finally, we did not include patients with ventricular tachycardia, another group that might be expected to have cannon a waves and therefore theoretically similar symptoms; indeed, this issue is further complicated by the fact that individuals with idiopathic ventricular tachycardia more often exhibit dual AV nodal physiology and AVNRT,14
making the interpretation of neck symptoms in these patients potentially quite difficult.
In conclusion, contrary to claims promulgated in prominent review articles and text books regarding the utility of neck fullness and witnessed neck pulsations during episodes of palpitations, neither helps to distinguish typical AVNRT from AF or AFL. Among subjects with known SVT (other than AF or AFL), witnessed neck pulsations are significantly more common in patients with typical AVNRT, with a high specificity and moderately high positive predictive value.