title: Effect of cough on heart rate and blood pressure in patients with "cough syncope".
abstract: BACKGROUND
  "Cough syncope" is uncommon, and its mechanism remains controversial.
  
  
  OBJECTIVE
  This study evaluated susceptibility to cough-triggered neural reflex hypotension-bradycardia among cough syncope patients. We hypothesized that individuals with cough syncope would manifest not only more profound cough-triggered hypotension than do other fainters but also an inappropriate chronotropic response accompanying cough-induced hypotension, thereby supporting the notion that a neural reflex hypotension-bradycardia contributes to the condition.
  
  
  RESULTS
  Three patient groups were studied. Group 1 patients (n = 9) had "cough syncope." The remaining patients had recurrent faints of other causes: group 2 (n = 13) had a positive head-up tilt test, and group 3 (n = 18) had a negative tilt test. With cough, group 1 patients exhibited a greater drop in systolic pressure (-51 +/- 19.3 mmHg) than did either group 2 (-23 +/- 11.1 mmHg, P < .04) or group 3 patients (-28 +/- 12.4 mmHg, P < .05). Recovery time to normalization of systolic pressure was greater in group 1 (25 +/- 9.1 seconds) than in group 2 or 3 (8 +/- 2.7 seconds and 9 +/- 6.1 seconds, respectively, both P < .01 vs group 1). The expected positive chronotropic response accompanying cough-induced hypotension was diminished in group 1 patients (0.16 +/- 0.21 bpm/mmHg) compared with that in either group 2 (0.74 +/- 0.60 bpm/mmHg, P < .05 vs group 1) or group 3 (0.33 +/- 0.15 bpm/mmHg, P = .06 vs group 1).
  
  
  CONCLUSIONS
  Cough syncope patients not only exhibit more pronounced hypotension in response to cough than other fainters, but they also manifest an inappropriate cough-triggered blood pressure-heart rate relationship. These findings argue in favor of the importance of a neurally mediated reflex contribution to symptomatic hypotension in cough syncope.
authors.affiliation: Cardiac Arrhythmia Center, Department of Medicine, Cardiovascular Division, University of Minnesota Medical School, Minneapolis, Minnesota, USA. bendi001@umn.edu
authors.forename: David G
authors.initials: DG
authors.lastname: Benditt
authors.forename: Nemer
authors.initials: N
authors.lastname: Samniah
authors.forename: Scott
authors.initials: S
authors.lastname: Pham
authors.forename: Scott
authors.initials: S
authors.lastname: Sakaguchi
authors.forename: Fei
authors.initials: F
authors.lastname: Lu
authors.forename: Keith G
authors.initials: KG
authors.lastname: Lurie
authors.forename: Cengiz
authors.initials: C
authors.lastname: Ermis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure; D001919:Bradycardia / Q000209:etiology; D003371:Cough / Q000150:complications*; D004198:Disease Susceptibility; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D007022:Hypotension / Q000209:etiology; D008297:Male; D008875:Middle Aged; D013575:Syncope / Q000209:etiology / Q000503:physiopathology*