Ventricular rate control during atrial fibrillation by cardiac parasympathetic nerve stimulation: a transvenous approach
Patrick Schauerte, MDa,b,
Benjamin J. Scherlag, PhD, FACCa,b,
Michael A. Scherlag, MDa,b,
Sunil Goli, MDa,b,
Warren M. Jackman, MD, FACCa,b and
Ralph Lazzara, MD, FACCa,b
a Cardiovascular Section, Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA
b Department of Veterans Affairs Medical Center, Oklahoma City, Oklahoma, USA
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Figure 1 Radiogram (90° right lateral view) showing the basket catheter at a successful cardiac nerve stimulation site in the RPA. Panel A illustrates the catheter arrangement before the injection of 20 ml of nonionic contrast medium in the right ventricle whereas panel B depicts the same site after injection of contrast medium. The intravascular stimulation site was located in the proximal RPA. In this dog, a basket catheter was also introduced into the CS. Panel C gives a schematic explanation. CS = coronary sinus; Hb = His bundle; LV = left ventricle; PA = pulmonary artery; RPA = right pulmonary artery.
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Figure 2 Fluoroscopic view (90° right lateral view) of an effective cardiac nerve stimulation site in the SVC. Panel A shows the basket catheter, which was introduced via the right jugular vein, in the SVC. Panel B shows the identical area after injection of 20 ml nonionic contrast medium into the SVC through the jugular vein. Due to the contrast medium, the basket catheter can hardly be seen but it is obvious from Panel A that the catheter was placed just distal to the entrance of the innominate vein from the left but proximal to the entrance of the SVC into the RA. A schematic view of the catheter arrangement and anatomy is shown in panel C. RA = right atrium; SVC = superior vena cava.
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Figure 3 Cardiac nerve stimulation in the CS. Surface ECG lead II, aVR and an RAA recording are depicted. Atrial fibrillation was induced and maintained by rapid pacing from the RAA at a cycle length of 100 ms (low frequency, low amplitude pacing artifacts on the right of the RAA tracing). Parasympathetic stimulation was done at a stimulus strength of 34 V and a frequency of 20 Hz (high frequency, high amplitude electrical artifacts can be seen on the left of the RAA tracing). The cycle length values within the figure refer to the longest and shortest R-R interval during AF with PS (1976 and 1440 ms, respectively) and when PS was terminated (arrow, 600 and 260 ms, respectively). AF = atrial fibrillation; CS = coronary sinus; PS = parasympathetic stimulation; RAA = right atrial appendage; R-R = ventricular rate.
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Figure 4 Effect of SST on R-R slowing during PS in the CS, RPA, and SVC. Average R-R intervals during AF are plotted versus the SST. The SST significantly affected the R-R interval during AF at all three intravascular sites (p < 0.001 each, ANOVA). The mean R-R interval at each SST was also compared with the R-R interval without PS (*p < 0.05). Of note, during epicardial PS at the CS ostium, the threshold for a ventricular slowing effect during AF was considerably lower than during endovascular PS in the CS. AF = atrial fibrillation; ANOVA = analysis of variance; CS = coronary sinus; PS = parasympathetic stimulation; RPA = right pulmonary artery; R-R = ventricular rate; SST = stimulus strength.
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Figure 5 Cardiac nerve stimulation (PS) in the SVC. Surface ECG leads I, II and aVF and a recording of the stimuli (stim) delivered to the basket catheter are depicted. Atrial fibrillation was induced and maintained by rapid pacing from the RAA at a cycle length of 100 ms (low frequency, low amplitude electrical artifacts). A vertical arrow in both panels indicates the onset of PS. At a PS intensity of 13 V, the shortest R-R interval during AF prolonged from 352 ms to 384 ms and the longest R-R interval from 408 to 1464 ms (panel A). Increasing the stimulus amplitude to 22 V led to an even greater increase of the R-R intervals (shortest: 272 ms to 1,008 ms; longest: 380 ms to 2,336 ms) as illustrated in panel B. AF = atrial fibrillation; PS = parasympathetic stimulation; RAA = right atrial appendage; R-R = ventricular rate; stim = stimuli; SVC = superior vena cava.
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Figure 6 Continuous parasympathetic cardiac nerve stimulation in the coronary sinus over 20.5 h. The R-R interval during AF is plotted versus time (see text for discussion). AF = atrial fibrillation; R-R interval = ventricular rate.
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