Article, Cardiology

The clinical characteristics of situational syncope in children and adults undergoing head-up tilt testing

a b s t r a c t

Objective: Situational syncope is a subtype of neurally mediated syncope and associated with specific circum- stances. This paper is to assess the clinical characteristics and underlying causes of situational syncope.

Methods: This is a retrospective study of patients who underwent head-up tilt testing (HUTT). Medical records including age at HUTT, gender, number of syncopal episodes, family history of syncope, triggers before the syn- copal episode, position during the syncopal episode and the responses to HUTT were reviewed.

Results: Among 3140 patients, 354 patients (mean age 28.3 +- 16.6 years old, with 184 males and 170 females) were diagnosed with situational syncope. The causes of situational syncope included micturition (50.85%), defe- cation (15.82%), bathing (10.45%), swallowing (6.50%), cough (4.80%), post-dinner (3.95%), singing (3.11%), teeth brushing (2.26%), and hair grooming (2.26%). Patients with syncope triggered by micturition, cough, post-dinner were more likely to be men, while those caused by bathing, swallowing, singing, teeth brushing and hair grooming were more likely to be women. 34.75% of patients with situational syncope were between the ages of 10-19 years old, and 20.34% were between the ages of 40-49 years old. 74.01% of situational syncopal events occurred in an upright position. 47.74% of patients had positive responses to HUTT.

Conclusions: These findings show that micturition was the most common cause of situational syncope in both children and adults. There were significant gender and age differences among situational syncope triggered by different causes. Most of situational syncope occurred in the upright position and nearly half of the patients had positive responses to HUTT.

(C) 2019

Introduction

Syncope is a symptom that presents with abrupt, transient and com- plete loss of consciousness due to Cerebral hypoperfusion, the inability to maintain postural tone, rapid onset and spontaneous recovery [1,2]. Syncope is common in the general population and has a bimodal distri- bution with increased frequency in teenagers and adults older than 40 years old. Approximately 40% of humans experience at least one syn- copal episode in a lifetime, accounting for about 1% of emergency

Abbreviations: ECG, electrocardiogram; HUTT, head-up tilt testing; OH, orthostatic hy- potension; OHT, orthostatic hypertension; POTS, postural orthostatic tachycardia syn- drome; VVS, vasovagal syncope; VVS-V, vasodepressor response of vasovagal syncope; VVS-C, cardioinhibitory response of vasovagal syncope; mixed VVS, mixed response of va- sovagal syncope.

* Corresponding author at: Department of Pediatric Cardiovasology, Children’s Medical Center, the Second Xiangya Hospital, Central South University & Institute of Pediatrics, Central South University, No. 139 Renmin Middle Road, Changsha 410011, Hunan, China.

E-mail address: [email protected] (C. Wang).

department visits [3]. Syncope can be divided into reflex syncope, car- diac syncope and unexplained syncope. Reflex syncope, also known as neurally mediated syncope, refers to a heterogeneous group of condi- tions in which cardiovascular reflexes become inappropriate in re- sponse to a trigger, contributing to vasodilatation and/or bradycardia, eventually resulting in a decrease of arterial blood pressure and cerebral perfusion [4]. Reflex syncope is the most frequent cause of syncope both in children and adults. Based on the triggers, reflex syncope may be clas- sified as neurally mediated syncope, situational syncope and carotid sinus syncope [1].

Situational syncope is associated with a specific circumstance. The Underlying etiology of situational syncope is unknown, but each sub- type is distinct and should be differentiated by Detailed history in order to draw a correct picture of the type of reflex involved. Situational syncope most commonly occurs during or immediately after swallowing, defecating, urinating, coughing, sneezing, laughing, and singing [5]. However, situational syncope also includes syncope occur- ring after exercise, during Blood donation or during eating. In this

https://doi.org/10.1016/j.ajem.2019.11.042

0735-6757/(C) 2019

Fig. 1. Etiological constitution of situational syncope.

retrospective study, we analyzed the etiological constitution and clinical characteristics of situational syncope both in children and adults through a single center and large sample-based study.

Methods

Study population and data abstraction

The patient population consisted of those patients who underwent head-up tilt testing (HUTT) at Syncope Ward, the Second Xiangya Hos- pital between January 2001 and November 2017. Three abstractors (one research associate and two medical postgraduates) used a standardized form to abstract electronic chart data including demographics and med- ical history from our HUTT database. Demographics and clinical charac- teristics included age at HUTT, gender, number of syncopal episodes, family history of syncope, syncopal episode triggers, position during each episode, and HUTT responses. The abstractors were blinded to the study hypotheses and completed a 1-hour training session. Agree- ment between chart reviewers was monitored. In case of contradictory evidence, the hierarchy was as follows: specialist attendant, generalist attendant, emergency attendant, resident and medical student. 3140 children and adults (mean age 24.5 +- 17.8 years, 1342 males and 1798 females) were retrospectively reviewed. These patients complained of syncope and had been referred from outpatient clinics, inpatient services or emergency departments. All these subjects underwent an initial evaluation consisting of History taking, physical

examination, baseline laboratory testing, and 12-lead electrocardio- gram (ECG). For suspected structural heart diseases or arrhythmias, an echocardiogram and 24 h ECG were performed. Patients were included if they had syncope during or immediately after specific situations. Ex- clusion criteria were the occurrence of syncope caused by structural heart diseases or disorders resembling syncope without loss of con- sciousness, such as cataplexy, transient ischemic attacks, cerebral vascu- lar accidents, or somatization disorders.

Definition of situational syncope

Situational syncope is defined as syncope occurring during or imme- diately after specific triggers including coughing, sneezing, laughing, singing, swallowing, defecating, urinating, eating, bathing, teeth brushing, hair grooming, stretching, and weightlifting [1,5].

HUTT

The HUTT protocol was performed according to a previous study [6]. HUTT was approved by the Ethics Committee of the Second Xiangya Hospital. Before HUTT, the informed consent was obtained from all the subjects directly or their guardians. Positive responses to HUTT in- cluded vasovagal syncope (VVS), postural orthostatic tachycardia syn- drome (POTS), orthostatic hypotension (OH), and orthostatic hypertension (OHT). VVS was defined as the development of syncope or presyncope accompanied by hypotension (systolic BP <= 80 mmHg

Table 1

Basic characteristics of the study population.

Causes

Numbers (%)

Age (years)

Sex

Syncopal episodes

Family history (n, %)

Male (%)

Female (%)

Micturition

180(5.73)

30.1 +- 15.7

114(63.33)

66 (36.67)

2.9 +- 2.2

29(16.11)

Defecation

56(1.78)

31.1 +- 17.2

22 (39.29)

34 (60.71)

3.5 +- 3.2

13(23.21)

Bathing

37(1.18)

25.3 +- 14.9

11 (29.73)

26 (70.27)

2.5 +- 1.9

6(16.22)

Swallowing

23(0.73)

22.9 +- 18.1

8 (34.78)

15 (65.22)

2.6 +- 2.0

2(8.70)

Coughing

17(0.54)

40.7 +- 16.9

13 (76.47)

4 (23.53)

2.7 +- 1.2

0

Singing

11(0.35)

15.2 +- 13.7

5 (45.45)

6 (54.55)

1.6 +- 0.9

1(9.09)

Post-dinner

14(0.45)

20.1 +- 13.7

9 (64.29)

5 (35.71)

1.5 +- 0.6

2(14.29)

Teeth brushing

8(0.25)

15.5 +- 9.5

2 (25.00)

6 (75.00)

2.2 +- 0.5

1(12.50)

Hair grooming

8(0.25)

16.1 +- 13.4

0

8 (100.00)

2.2 +- 0.7

3(37.50)

Total

354(11.27)

28.3 +- 16.6

184 (51.98)

170 (48.02)

2.8 +- 2.3

58(16.38)

age distribution of different situa”>Table 2

Age distribution of different situational syncope.

Causes

<10 years

10-19 years

20-29 years

30-39 years

40-49 years

50-59 years

60-69 years

>70 years

Micturition (n=180)

4 (2.22)

64 (35.55)

20 (11.11)

30 (16.67)

40 (22.22)

15 (8.33)

7 (3.89)

0

Defecation (n=56)

3 (5.36)

19 (33.93)

7 (12.50)

4 (7.14)

14 (25.00)

7 (12.50)

1 (1.78)

1 (1.78)

Bathing (n=37)

3 (8.10)

14 (37.84)

7 (18.92)

4 (10.81)

7 (18.92)

1 (2.70)

1 (2.70)

0

Swallowing (n=23)

8 (34.78)

4 (17.39)

4 (17.39)

1 (4.35)

3 (13.04)

3 (13.04)

0

0

Coughing (n=17)

1 (5.88)

2 (11.76)

1 (5.88)

2 (11.76)

5 (29.41)

5 (29.41)

1 (5.88)

0

Singing (n=11)

4 (36.36)

6 (54.55)

0

0

0

1 (9.09)

0

0

Post-dinner (n=14)

3 (21.43)

6 (42.86)

1 (7.14)

2 (14.29)

2 (14.29)

0

0

0

Teeth brushing (n=8)

2 (25.00)

4 (50.00)

1 (12.50)

1 (12.50)

0

0

0

0

Hair grooming (n=8)

2 (25.00)

4 (50.00)

1 (12.50)

0

1 (12.50)

0

0

0

Total (n=354)

30 (8.47)

123 (34.75)

42 (11.86)

44 (12.43)

72 (20.34)

32 (9.04)

10 (2.82)

1 (0.28)

Note: All values are No. of patients (%).

in children, <90 mmHg in adults, and/or Diastolic BP <= 50 mmHg, or over 25% decrease in mean blood pressure), bradycardia (HR<50 bpm in adults, <75 bpm in children between 4 and 6 years old, <65 bpm in children between 6 and 8 years old, <60 bpm in children above 8 years old), or cardiac arrest >3 s [7,8]. VVS was further classified

into three responses: vasodepressor response (significant reduction in BP but insignificant change in HR), cardioinhibitory response (signifi- cant reduction in HR but insignificant change in BP) and mixed response (significant reduction both in BP and HR) [9].

POTS was defined as dizziness, chest distress, headache, palpitation, pallor and one of the following within 10 min of HUTT: an increase in HR

(1) >= 40 bpm in children and adolescents, (2) >= 30 bpm in adults, or by a maximum HR (3) > 130 bpm in children between 6 and 12 years old, (4)

> 125 bpm in adolescents between 13 and 18 years old [2,10]. OHT was

defined as (within 3 min of HUTT) orthostatic intolerance symptoms

and an increase in systolic BP >= 20 mmHg, and/or diastolic BP incre- ments >= 25 mmHg in children between 6 and 12 years old, >=20 mmHg in adolescents between 13 and 18 years old), >=10 mmHg in adults; or upright BP >= 130/90 mmHg in children between 6 and 12 years old,

>=140/90 mmHg in adolescents between 13 and 18 years old without an obvious change in HR [10]. OH was defined as a sustained decrease in systolic BP of at least 20 mmHg or diastolic BP of at least 10 mmHg within 3 min of HUTT [10,11].

Statistical analysis

All data were analyzed using SPSS 17.0. Continuous data were expressed as mean +- SD values. Dichotomized variables were expressed as percent prevalence.

Results

The basic characteristics of the study population

354 (11.27%) patients with syncope (aged 4-78 years with mean age 28.3 +- 16.6 years, 184 males and 170 females), were diagnosed with situational syncope. As shown in Fig. 1, situational syncope triggers were micturition, defecation, bathing, swallowing, coughing, post- dinner, singing, teeth brushing, and hair grooming. As shown in Table 1, patients with syncope triggered by micturition, coughing, or post-dinner tended to be men, while those triggered by defecation, bathing, swallowing, singing, teeth brushing, or hair grooming were tended to be women. Most of the study population experienced more than one syncopal episodes and the mean number of syncopal episodes was 2.8 +- 2.3. 16.38% of patients had family history of syncope.

Age distribution of different situational syncope

As shown in Table 2 and Fig. 2, micturition syncope and defecation syncope both had a bimodal age distribution, occurring most commonly between the ages of 10-19 years old (35.55% and 33.93%, respectively) and 40-49 years old (22.22% and 25.00%, respectively). Most of the pa- tients with situational syncope triggered by bathing, post-dinner, teeth brushing and hair grooming aged from 10 to 19 years old (37.84%, 42.86%, 50.00%, 50.00% respectively). Swallowing syncope was com- monly seen in children younger than 10 years old (34.78%). Cough syn- cope frequently occurred between the ages of 40-59 years old (58.82%). Situational syncope triggered by singing was most commonly seen in patients younger than 20 years old, except for one patient who was 56 years old. In total, 34.75% of patients with situational syncope were

Fig.2. Age distribution of different situational syncope.

Table 3

Position at the onset of syncope.

Causes

Upright position

sitting position

kneeling-squatting position

From sitting to upright position

From kneeling -squatting to upright position

Micturition (n = 180)

159 (88.33)

2 (1.11)

11 (6.11)

1 (0.56)

7 (3.89)

Defecation (n = 56)

22 (39.29)

2 (3.57)

12 (21.43)

1 (1.79)

19 (33.93)

Bathing (n = 37)

34 (91.89)

1 (2.70)

1 (2.70)

1 (2.70)

0

Swallowing (n = 23)

12 (52.17)

11 (47.83)

0

0

0

Coughing (n = 17)

3 (17.65)

13 (76.47)

0

1 (5.89)

0

Singing (n = 11)

7 (63.63)

4 (36.36)

0

0

0

Post-dinner (n = 14)

10 (71.42)

2 (14.29)

0

2 (14.29)

0

Teeth brushing (n = 8)

8 (100.00)

0

0

0

0

Hair grooming (n = 8)

7 (87.50)

1 (12.50)

0

0

0

Total (n = 354)

262 (74.01%)

36 (10.17%)

24 (6.78%)

6 (1.69%)

26 (7.34%)

Note: All values are No. of patients (%).

between 10 and 19 years old, 20.34% were between 40 and 49 years old, 11.86% were between 20 and 29 years old, and 8.47% were younger than 10 years old.

Position during the syncopal episode

As shown in Table 3, position during syncopal episodes included up- right (74.01%), sitting (10.17%), kneeling-squatting position (6.78%), position change from kneeling-squatting to upright (7.34%), and posi- tion change from sitting to upright (1.69%). Syncope caused by micturi- tion, defecation, bathing, swallowing, singing, post-dinner, teeth brushing, and hair grooming frequently occurred while upright, whereas syncope caused by coughing commonly occurred while sitting.

Responses to HUTT

All situational syncope patients underwent HUTT. As shown in Table 4, 47.74% of patients had a positive response to HUTT, and the most frequent response was vasodepressor (28.81%), followed by mixed (16.67%), then cardioinhibtory (1.13%) and POTS (1.13%). No OH or OHT was found.

Discussion

Situational syncope is a subdivision of reflex syncope and closely re- lated to a specific situation. The precise pathophysiology is not completely understood. In this study, micturition and defecation were the most common triggers in the study population, following is bathing, swallowing, coughing, post-dinner, singing, teeth brushing and hair grooming. Mechanoreceptors are present throughout the body includ- ing bladder, rectum, esophagus, and lungs. Sudden activation of a large number of these receptors sends afferent signals to the brain, which provokes a paradoxical reflex resulting in bradycardia and hypo- tension. Micturition syncope is mainly triggered by vagal reflexes de- rived from genitourinary mechanoreceptor stimulation, while

defecation syncope is triggered by vagal reflexes derived from gastroin- testinal mechanoreceptor stimulation [12]. Swallowing syncope is trig- gered by vagal afferent activation due to esophageal stimulation and mechanical compression of the cardiac chamber, contributing to a sud- den and transient reduction in cardiac output and an increase in Vagal tone [13]. Singing, continuous cough and intense laughter lead to syn- cope by increasing intrathoracic pressure, similar to a Valsalva maneu- ver, contributing to a decrease in venous return and cerebral hypoperfusion [14,15]. Hair grooming syncope is induced by pain or nerve stimulation on the scalp, and compression of the blood vessels or nerves through neck flexion or extension [16]. When taking a hot bath, the sympathetic tone is decreased without compensatory sup- pression of vagal tone, contributing to hypotension and bradycardia. Glossopharyngeal nerve is stimulated when brushing teeth, then stimu- lation is transmitted to carotid sinus, which results in a decrease in Blood pressure and heart rate.

Situational syncope has significant gender and age differences across different triggers. In our study, micturition syncope was more common in male teenagers and middle-aged men, whereas defecation syncope tended to occur in female teenagers and middle-aged women. Consis- tent with our results, male dominance in micturition syncope and fe- male dominance in defecation syncope have been reported, but previous studies have not shown a bimodal distribution of age [12,17]. Compared with defecation syncope, micturition syncope tended to occur in younger patients. Swallowing syncope occurred mainly in fe- males and children younger than 10 years old in our study. However, the literature has suggested that swallowing syncope is more common in adult males [18]. It is thought that swallowing syncope is associated with a cardiac disorder such as myocardial infarction and Digoxin use, or an esophageal disorder, such as esophageal spasm and esophageal stricture [13]. In our study, those who with swallowing syncope had no underlying cardiac or esophageal disease. Cough syncope often oc- curred in middle-aged, overweight males. This population has been noted to be more prone to have lung diseases [19]. Hair grooming syn- cope was most typically seen in female children and teenagers. This is

Table 4

Responses to head-up tilt test.

Causes

VVS-V

VVS-C

mixed VVS

POTS

positive rate

Micturition (n = 180)

51 (28.33)

3 (1.67)

31 (17.22)

0

85 (47.22)

Defecation (n = 56)

13 (23.21)

0

15 (26.79)

0

28 (50.00)

Bathing (n = 37)

17 (45.94)

0

6 (16.22)

1 (2.70)

24 (64.86)

Swallowing (n = 23)

5 (21.74)

1 (4.35)

1 (4.35)

0

7 (30.43)

Coughing (n = 17)

2 (11.76)

0

1(5.89)

0

3 (17.65)

Singing (n = 11)

4 (36.36)

0

1 (9.09)

1 (9.09)

6(54.55)

Post-dinner (n = 14)

2 (14.29)

0

2 (14.29)

1 (7.14)

5 (35.71)

Teeth brushing (n = 8)

3 (37.50)

0

1(12.50)

1(12.50)

5 (62.50)

Hair grooming (n = 8)

5 (62.50)

0

1(12.50)

0

6 (75.00)

Total (n = 354)

102 (28.81)

4 (1.13)

59 (16.67)

4(1.13)

169 (47.74)

Note: All values are No. of patients (%).

VVS-V: vasodepressor response of vasovagal syncope. VVS-C: cardioinhibitory response of vasovagal syncope. Mixed VVS: mixed response of vasovagal syncope.

consistent with previous studies [20]. In our study, syncope induced by bathing, and teeth brushing occurred more frequently in teenagers and females, while syncope induced by post-dinner and singing occurred more common in teenagers and males. These data suggest that different subtypes of situational syncope are associated with various daily activities.

In previous studies, positive responses to HUTT did not include other types of orthostatic intolerance like POTS. Situational syncope showed poor positive response (38%) to HUTT [7]. In the present study, nearly half of the patients with situational syncope had a positive response, and the most frequent response was vasodepressor. Both micturition syncope and defecation syncope frequently had vasodepressor and mixed responses to HUTT, which is consistent with the previous study [12]. In our current study, among the 17 patients who had cough syn- cope, 3 patients (17.64%) had a positive response to HUTT, with two pa- tients demonstrating a vasodepressor response and one patient demonstrating a mixed response. In a previous study, 48% of patients with cough syncope had a positive response to HUTT, and 37% of pa- tients had vasovagal response with 70% being vasodepressor response [21]. The positive rate in our study was lower, possibly due to a small sample sized patients with cough syncope. Studies demonstrated that 28% of patients with situational syncope had experienced occasional ep- isodes of VVS, a similar positive response rate to HUTT when compared to patients without VVS attacks [22]. This suggests that HUTT has a diag- nostic value in situational syncope.

Most of the situational syncope occurred at the upright position in this study. Like for VVS, treatment strategies for situational syncope in- clude education and non-pharmacological physical treatments. Early recognition of prodromal symptoms and avoidance of triggers may be effective to prevent the occurrence of situational syncope. Additionally, adequate intake of water and salt to maintain central volume, slower changes in posture and protected posture can attenuate the response. However, the prognosis of different triggers of situational syncope was not elucidated in our study.

Conclusions

We analyzed the clinical characteristics of situational syncope and revealed varieties of triggers based on a large sample-based study. The most common trigger of situational syncope was micturition both in children and adults. There are significant gender and age differences across the different situational syncope. Most of the situational syncope occurred at the upright position and nearly half of the patients had pos- itive responses to HUTT.

Study limitation

This study was retrospective in design and performed at a single center. Referral bias may have affected the results of our study. First, generalizability of the study findings is restricted. We evaluated only the natural history and characteristics of patients undergoing HUTT but not in the general population, those patients who had situational syncope but didn’t receive HUTT were not included. This might affect the incidence of situational syncope. Second, the data were just ab- stracted from HUTT database, but not from the patient interview, the medical history may not be very detailed. For those who had recurrent syncope episodes, there may be more than one cause, but only the

main cause was abstracted. Additionally, the prognosis of different types of situational syncope should to be investigated in future studies.

Acknowledgments

We thank all participating patients.

Declaration of Competing Interest

The authors declare that they have no competing interests.

Appendix A. Supplementary material

Supplementary data to this article can be found online at https://doi. org/10.1016/j.ajem.2019.11.042.

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