Original-clinicalEffect of cough on heart rate and blood pressure in patients with “cough syncope”
Introduction
Vigorous cough often triggers symptomatic hypotension in the form of transient “lightheadedness,” but complete loss of consciousness (so-called ‘cough syncope’) is uncommon.1 Given the infrequent occurrence of cough syncope, few studies have addressed its pathophysiology, and each has been able to evaluate only small numbers of patients.2, 3, 4, 5, 6, 7 Consequently, although cough syncope is widely recognized by clinicians, the basis for susceptibility to cough-triggered faints remains incompletely understood.
Various mechanisms have been proposed as the basis for cough syncope. For instance, it has been suggested that prolonged spasms of coughing impair venous return to the heart, resulting in decreased cardiac output and reduced systemic pressure.2 Alternatively, it has been argued that sustained coughing increases cerebrospinal fluid pressure and thereby initiates loss of consciousness by an ill-defined cerebral ischemia mechanism.3, 4 However, cough-induced hypotension, and even ‘cough syncope,’ may occur without prolonged periods of coughing. Thus, it has been presumed that, at least in some affected individuals, an abrupt transient increase of intraarterial pressure may trigger hypotension via a baroreceptor-initiated neural vasodilator-bradycardia reflex comparable to that believed responsible for other forms of neurally mediated reflex syncope.
In this study, we sought to determine whether individuals prone to cough syncope differ from fainters of other etiologies in terms of their hemodynamic response to a brief cough “intervention.” Specifically, we hypothesized that cough syncope patients would manifest not only a more pronounced cough-induced hypotension but that their chronotropic response to cough-triggered hypotension would be inappropriate. To this end, we measured the impact of a brief cough-induced arterial pressure impulse on heart rate and blood pressure in fainters of various etiologies.
Section snippets
Methods
All patients included in this study had been referred to the Cardiac Arrhythmia Center at the University of Minnesota, Minneapolis, Minnesota, or the Cardiac Arrhythmia Service at Central Minnesota Heart Center, St. Cloud, Minnesota, for evaluation of recurrent syncope. Three patient groups were identified. Group 1 patients consisted of individuals with a history compatible with “cough syncope.” These individuals presented with a history of two or more syncope episodes closely associated with
Clinical features
The study population comprised 40 individuals referred for diagnostic evaluation and treatment of syncope (Table 1). Group 1 consisted of 9 individuals (2 women and 7 men; age 64 ± 7.1 years) with a medical history compatible with cough syncope. In three cases, single or brief periods of coughing caused symptoms; in four cases, the history suggested longer coughing spasms were responsible; and in two instances the history was unclear. Head-up tilt testing was positive (i.e., induced syncope) in
Discussion
Cough syncope is an infrequent but well-recognized condition that has remained incompletely understood despite a number of important studies examining its pathophysiology.2, 3, 4, 5, 6, 7 In this context, this study provides four principal findings regarding blood pressure and heart rate responses associated with susceptibility to cough syncope. First, despite exposure to only a brief cough-induced pressure pulse (>220 mmHg) while in the supine position, individuals susceptible to ‘cough
Conclusion
Cough-induced syncope is a recognized clinical entity but one in which the pathophysiology remains controversial.1, 14 Findings reported here indicate that cough syncope patients exhibit more pronounced hypotension and a slower recovery process in response to cough than do fainters of other etiologies. This response occurs with even very brief cough stress with the patients in the supine position, tending to diminish the probability of a cerebral ischemia mechanism. In addition, our
Acknowledgments
We acknowledge the Electrophysiology Laboratory staff at Fairview-University Medical Center, Minneapolis, Minnesota, and at the Central Minnesota Heart Center, St. Cloud, Minnesota, for assistance with this project, and Barry L.S. Detloff for assistance with the illustrations.
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Cited by (39)
The Wide-Ranging Spectrum of Cough-Induced Complications and Patient Harm
2020, American Journal of MedicineBlunted Chronotropic Response to Hypotension in Cough Syncope
2016, JACC: Clinical ElectrophysiologyA Case of Cough-induced Ventricular Tachycardia in a Patient with a Left Ventricular Assist Device
2016, Cardiac Electrophysiology ClinicsSubdural Hematoma Presenting as Recurrent Syncope
2015, Journal of Emergency MedicineCough syncope
2014, Respiratory MedicineCitation Excerpt :As early as 1953, a baroreflex mechanism was implicated in the etiology of cough syncope [8]. Over a half century later, Benditt and colleagues [71] shed further light on this issue by comparing the effects of a brief, volitional cough effort (requiring the induction of a transient increase in systolic blood pressure to > 220 mm Hg) in subjects with a history of cough syncope and individuals with syncope of other etiologies. The investigators reported a number of significant observations.
This work was supported in part by grants from the Midwest Arrhythmia Research Foundation, Edina, Minnesota, to Drs. Samniah and Ermis.