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Modified carotid sinus massage using an ultrasonography for maximizing vagal tone: a crossover simulation study☆☆☆★★★
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Fig. 1
Visual representation of the comparing of the position of the 2 points obtained with each maneuver. The x-axis was defined as the midline of the neck and the y-axis as the angle of the mandible. The distance between the points was determined by measuring with a ruler.
Fig. 2
Distribution of the pressure points obtained with each maneuver. The location of the conventional CSM is shown as a hollow, round shape and that of the modified CSM is shown as a solid, diamond shape. The pressure point of the modified CSM tended to be located more laterally and superiorly than the point of the conventional CSM.
Article Outline
Abstract
Introduction
The aim of this study was to ascertain if a modified carotid sinus massage (CSM) using ultrasonography is superior to the conventional CSM for vagal tone generation.
Methods
This was a prospective, crossover, clinical trial including 30 subjects with sinus rhythm. Participants were paired, and they performed 2 types of CSM to each other. To perform the conventional technique, pressure was exerted at the point where the maximal impulse of the carotid pulse was palpated. In the modified technique, participants localized the point of maximal diameter just above the bifurcation of the common carotid artery using ultrasonography and applied pressure to that point. Mean differences between premaneuver and postmaneuver R-R intervals and heart rates were compared. The distance from the midline of the neck (x distance) to the angle of the mandible (y distance) was measured, and the mean distance between the 2 techniques was compared.
Results
The baseline mean premaneuver R-R interval and heart rate did not differ significantly between the 2 techniques. The postmaneuver R-R interval and heart rate as well as the mean R-R interval and heart rate differences were significantly greater in the modified CSM. The mean location determined using the modified CSM was located 0.8 cm lateral and 0.8 cm superior to the mean location of the conventional CSM.
Conclusion
The modified CSM using ultrasonography might be more useful than the conventional CSM in reverting episodes of paroxysmal supraventricular tachycardia and may be a suitable alternative for treating the same in the emergency department.
1. Introduction
Carotid sinus massage (CSM), a simple and low-cost technique with various diagnostic and therapeutic indications, can be performed at the bedside with a very low incidence of complications [1x[1]Lown, B. and Levine, S.A. The carotid sinus: clinical value of its stimulation. Circulation. 1961;
23: 766–789
CrossRef | PubMedSee all References][1]. Diagnostic indications include the study of carotid sinus hypersensitivity and the so-called carotid sinus syncope [[1]x[1]Lown, B. and Levine, S.A. The carotid sinus: clinical value of its stimulation. Circulation. 1961;
23: 766–789
CrossRef | PubMedSee all References, [2]x[2]Brignole, M., Alboni, P., Benditt, D.G., Bergfeldt, L., Blanc, J.J., Bloch Thomsen, P.E. et al. Guidelines on management (diagnosis and treatment) of syncope—update 2004. Europace. 2004;
6: 467–537
CrossRef | PubMed | Scopus (482)See all References, [3]x[3]Scanavacca, M.I., de Brito, F.S., Maia, I., Hachul, D., Gizzi, J., Lorga, A. et al. Guidelines for the evaluation and treatment of patients with cardiac arrhythmias. Arq Bras Cardiol. 2002;
79: 1–50
PubMedSee all References], whereas therapeutic indications include the possibility of reverting episodes of paroxysmal supraventricular tachycardia (PSVT) [[1]x[1]Lown, B. and Levine, S.A. The carotid sinus: clinical value of its stimulation. Circulation. 1961;
23: 766–789
CrossRef | PubMedSee all References, [3]x[3]Scanavacca, M.I., de Brito, F.S., Maia, I., Hachul, D., Gizzi, J., Lorga, A. et al. Guidelines for the evaluation and treatment of patients with cardiac arrhythmias. Arq Bras Cardiol. 2002;
79: 1–50
PubMedSee all References]. Carotid sinus massage is performed by exerting pressure for a period of 10 seconds using longitudinal movements at the point where the maximum impulse of the carotid pulse is palpated, that is, immediately above the thyroid cartilage and below the angle of the mandible. The purpose of CSM is to stimulate the carotid body and raise vagal tone. However, as the point of maximal carotid impulse and the site of the carotid body may not be identical in each patient, CSM is a blind approach. The carotid body, located close at the bifurcation of the common carotid artery, can be easily identified and pressure applied at the bifurcation site directly using ultrasonography. This may be a more effective approach for maximizing vagal tone than the conventional CSM method. In this study, we aimed to investigate whether the modified CSM using ultrasonography is more effective in raising vagal tone than the conventional CSM method.
2. Methods
2.1. Study design and participants
A pilot study was conducted before the initiation of this randomized, crossover trial to determine the required minimum sample size. Assuming a power of 80% and a significance level of 5%, a sample size of 30 participants in each group was found to be sufficient. Subsequent to review and approval by the Kangdong Sacred Heart Hospital Institutional Review Board, 32 medical students were recruited for voluntary participation, and after explaining the purpose and nature of the study, written informed consent was obtained from all. The participants were then asked to complete a questionnaire that included basic demographic data.
Inclusion criteria were sinus rhythm on initial electrocardiography (ECG) and self-reported good general health. Exclusion criteria were any regular medication (other than oral contraceptives) and a previous diagnosis of cardiovascular or respiratory disease. Participants were requested to refrain from smoking and consuming alcohol or caffeine during the 6 hours before testing.
An introduction on CSM including a visual demonstration on how to find the carotid body using ultrasonography was provided to all participants before the test. Participants were paired using a random numbers table to perform the 2 types of CSM on each other. During the conventional CSM, pressure was exerted for a period of 10 seconds using longitudinal movements at the point where the maximum impulse of the carotid pulse was palpated, that is, immediately above the thyroid cartilage and below the angle of the mandible. To perform the modified CSM, participants searched the point of maximal diameter located just above the bifurcation of the common carotid artery using ultrasonography and applied pressure to that point for 10 seconds. All tests were performed in the supine position only, on the right side, and in an environment where a cardiac defibrillator and cardiopulmonary resuscitation equipment were available. All participants performed the conventional CSM first to prevent them from remembering the location of the carotid bifurcation identified by ultrasonography.
During each maneuver, cardiac activity was recorded on a continuous ECG strip (lead II) running at 25 mm/s (MAC 1200 ST Resting ECG System; GE Healthcare, Freiburg, Germany). Points denoting the beginning and the end of the CSM were marked on the ECG strip as references for subsequent R-R interval measurement. The linear R-R interval, used as an indirect measure of the level of vagal tone, was measured directly from ECG traces using a ruler and converted to time intervals. The premaneuver R-R interval was calculated using the mean of 10 consecutive R-R intervals preceding the onset of each maneuver. The postmaneuver R-R interval was the single longest R-R interval within 15 seconds of termination of the maneuver as described by Wong and Taylor [4x[4]Wong, L.F. and Taylor, D. Vagal response varies with Valsalva maneuver technique: a repeated-measures clinical trial in healthy subjects. Ann Emerg Med. 2004;
43: 477–482
Abstract | Full Text | Full Text PDF | PubMed | Scopus (17)See all References][4]. The study end points were the mean difference in R-R interval (postvalue minus prevalue, in seconds) and the mean difference in heart rate (postvalue minus prevalue, in beats per minute).
We compared the position of the 2 points identified by each maneuver. The x-axis was defined as the midline of the neck and the y-axis as the angle of the mandible. The distance between the 2 maneuver points determined using the x- and y-axes was measured with a ruler, and the mean x and y distances between the 2 points were compared (Fig. 1Fig. 1).
Data were analyzed using SPSS 19.0 software for windows (IBM, Inc, Armonk, NY). Descriptive statistics were used to characterize the study population. Mean values were compared using a paired Student t test. The level of statistical significance was defined as P < .05.
3. Results
From a total of 32 participants enrolled, 2 showed abnormalities on baseline ECG strips and were excluded from the study. The remaining participants had a mean age of 23 ± 2.4 years, and 24 were men (80%). All participants were medical students and had theoretical knowledge but no real experience of CSM using the human body as a target.
Comparisons of the mean premaneuver and postmaneuver R-R intervals, heart rates, and mean change between the 2 techniques are reported in the Table 1Table 1. Although the means of postmaneuver R-R interval and heart rate were significantly higher using the modified CSM, the difference was not statistically significant. However, the mean R-R interval and heart rate differences were significantly greater in the modified CSM than the conventional CSM.
| CSM | Modified CSM | Mean difference | P | |
|---|---|---|---|---|
| Mean premaneuver R-R intervalaa | 0.83 ± 0.14 | 0.82 ± 0.14 | 0.01 ± 0.06 | .177 |
| Mean postmaneuver R-R intervalaa | 0.96 ± 0.18 | 1.00 ± 0.19 | 0.04 ± 0.07 | .002 |
| Mean R-R interval differenceaa | 0.12 ± 0.09 | 0.19 ± 0.13 | 0.07 ± 0.08 | <.001 |
| Mean premaneuver heart ratebb | 72.07 ± 9.98 | 71.0 ± 9.95 | 1.10 ± 3.84 | .127 |
| Mean postmaneuver heart ratebb | 66.97 ± 10.52 | 65.03 ± 10.50 | 1.93 ± 3.28 | .003 |
| Mean heart rate differencebb | 5.03 ± 3.00 | 6.03 ± 3.29 | 1.00 ± 2.61 | .045 |
All data are presented as mean ± SD.
The pressure point of the modified CSM tended to be located more laterally and superiorly than the point of the conventional CSM. The mean point location of the modified CSM was situated 0.8 cm lateral and 0.8 cm superior to the mean point location of the conventional CSM (Fig. 2Fig. 2).
Fig. 2
Distribution of the pressure points obtained with each maneuver. The location of the conventional CSM is shown as a hollow, round shape and that of the modified CSM is shown as a solid, diamond shape. The pressure point of the modified CSM tended to be located more laterally and superiorly than the point of the conventional CSM.
4. Discussion
The CSM is generally used as a safe and effective procedure to attempt the termination of supraventricular tachycardia in the medical emergency setting. This study shows that the modified CSM using ultrasonography generates a more potent vagal tone than the conventional CSM, resulting in significant decreases in the heart rate of healthy subjects.
Ultrasonography appears to be a safe, noninvasive, and nonionizing imaging modality that can be used at bedside [5x[5]American College of Emergency Physicians. Emergency ultrasound guidelines. Ann Emerg Med. 2009;
53: 550–570
Abstract | Full Text | Full Text PDF | PubMed | Scopus (234)See all References][5]. Ultrasonography-guided procedures may improve the success and decrease complications associated with a number of techniques, including central venous access, thoracentesis, paracentesis, pericardiocentesis, arthrocentesis, regional anesthesia, incision and drainage of abscesses, localization and removal of foreign bodies, lumbar puncture, and biopsies. In addition to the diagnostic applications of ultrasonography, it can also be used to monitor the response to therapeutic interventions, such as the assessment of intravascular volume status in response to intravenous fluid therapy by measuring the respiratory changes in the diameter of the inferior vena cava [6x[6]Vitz, A.J., Noble, V.E., Bierig, M., Goldstein, S.A., Jones, R., Kort, S. et al. Focused cardiac ultrasound in the emergent setting: a consensus statement of the American College of Emergency Physicians. JASE. 2010;
23: 1225–1230
PubMedSee all References][6]. Moreover, ultrasonography is currently widely used in the field of emergency medicine.
All the students who participated in this study used an ultrasonography instrument for the first time, but there was no difficulty in finding the location of the carotid sinus. Although the modified CSM takes slightly longer than the conventional CSM, most patients with PSVT are stable, and the extra time needed will not have an effect on patient outcomes.
In addition, as ultrasonography can be used for the diagnosis of carotid artery thrombosis [[7]x[7]Schellack, J., Fulenwider, J.T., Olson, R.A., Smith, R.B. III, and Mansour, K. The carotid sinus syndrome: a frequently overlooked cause of syncope in the elderly. J Vasc Surg. 1986;
4: 376–383
Abstract | Full Text | Full Text PDF | PubMed | Scopus (14)See all References, [8]x[8]Toorop, R.J., Scheltinga, M.R., Bender, M.H., Charbon, J.A., Huige, M.C., Moll, F.L. et al. Effective surgical treatment of the carotid sinus syndrome. J Cardiovasc Surg. 2009;
50: 683–686
PubMedSee all References, [9]x[9]Cheng, L.H. and Norris, C.W. Surgical management of the carotid sinus syndrome. Arch Otolaryngol. 1973;
97: 395–398
CrossRef | PubMed | Scopus (8)See all References], contraindications for CSM can be identified before performing the procedure, which can be particularly useful in patients with carotid artery stenosis, in whom a thrombus can exist without a bruit being detected on auscultation. Therefore, thrombus destruction before CSM will reduce the complications resulting from CSM. In this study, there was no need to detect the presence of a carotid artery thrombus because the participants were healthy young students. However, further clinical studies including patients are necessary to establish firm conclusions.
In this study, the location point detected using the modified CSM is more superior and lateral than that of the conventional CSM. This suggests that a short distance exists between the pressing point determined using the conventional CSM and the carotid sinus. The approximately 1-cm distance seen in this study may be meaningless because the CSM is a blind and less specific maneuver in which pressure is applied on the skin. However, the modified CSM showed a significantly greater decrease in vagal tone compared with that of the conventional CSM. Although the difference is clinically small, it may change a patient's heart rhythm.
In this study, although a researcher educated the participants to apply a hard and constant pressure, it is differences in the level of pressure applied between participants that may have influenced the conclusions. We considered measuring the pressure exerted by checking the resulting depth using a pressure gauge. However, as determination of pressure intensity using this tool may be meaningless because of the variability in neck thickness and anatomic morphology, the application of this method might be difficult in the field. Therefore, variation in pressure intensity appears to be a limitation of this study.
This study has another important limitation. It was conducted on healthy subjects with sinus rhythm and without a history of supraventricular tachycardia, and we used the R-R interval as a proxy for measuring vagal tone. Accordingly, the extrapolation of our findings to subjects with supraventricular tachycardia is questionable because, like in most arrhythmias, considerable hemodynamic and electrophysiologic disturbances may exist.
However, as most subjects with supraventricular tachycardia have normal autonomic nervous system reflexes, it is reasonable to recommend the CSM that produces the longer postmaneuver R-R interval in subjects with sinus rhythm. Only a large clinical trial will confirm the efficacy of the modified CSM.
In conclusion, the modified CSM using ultrasonography might be more useful than the conventional CSM in reverting episodes of PSVT and may be a suitable alternative for treating PSVT in the emergency department.
References
- [1]Lown, B. and Levine, S.A. The carotid sinus: clinical value of its stimulation. Circulation. 1961; 23: 766–789
- [2]Brignole, M., Alboni, P., Benditt, D.G., Bergfeldt, L., Blanc, J.J., Bloch Thomsen, P.E. et al. Guidelines on management (diagnosis and treatment) of syncope—update 2004. Europace. 2004; 6: 467–537
- [3]Scanavacca, M.I., de Brito, F.S., Maia, I., Hachul, D., Gizzi, J., Lorga, A. et al. Guidelines for the evaluation and treatment of patients with cardiac arrhythmias. Arq Bras Cardiol. 2002; 79: 1–50
- [4]Wong, L.F. and Taylor, D. Vagal response varies with Valsalva maneuver technique: a repeated-measures clinical trial in healthy subjects. Ann Emerg Med. 2004; 43: 477–482
- [5]American College of Emergency Physicians. Emergency ultrasound guidelines. Ann Emerg Med. 2009; 53: 550–570
- [6]Vitz, A.J., Noble, V.E., Bierig, M., Goldstein, S.A., Jones, R., Kort, S. et al. Focused cardiac ultrasound in the emergent setting: a consensus statement of the American College of Emergency Physicians. JASE. 2010; 23: 1225–1230
- [7]Schellack, J., Fulenwider, J.T., Olson, R.A., Smith, R.B. III, and Mansour, K. The carotid sinus syndrome: a frequently overlooked cause of syncope in the elderly. J Vasc Surg. 1986; 4: 376–383
- [8]Toorop, R.J., Scheltinga, M.R., Bender, M.H., Charbon, J.A., Huige, M.C., Moll, F.L. et al. Effective surgical treatment of the carotid sinus syndrome. J Cardiovasc Surg. 2009; 50: 683–686
- [9]Cheng, L.H. and Norris, C.W. Surgical management of the carotid sinus syndrome. Arch Otolaryngol. 1973; 97: 395–398
☆Contributorship statement: GC Cho planned the study. SM Ha and CH Jo conducted the survey. YS Cho and JY Ryu analyzed the results. SM Ha and YS Cho contributed equally to this study as primary authors.
☆☆Funding: This study did not receive research funding from any funding agency.
★Conflict of interest: The authors declare no financial or other conflicts of interest relevant to the content of this manuscript.
★★Provenance and peer review: Not commissioned; externally peer reviewed.
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