Effects of respiration and posture on paroxysmal supraventricular tachycardia.

Abstract

SUMMARY The capacity of deep inspiration and the dependent body position to terminate episodes of tachycardia was studied in 11 patients with recurrent paroxysmal supraventricular tachycardia (PSVT). In eight patients, a deep inspiration and a dependent position repeatedly terminated episodes of PSVT. Reasons for failure were found in the other three patients. A deep inspiration or assumption of a dependent position dramatically raised arterial blood pressure and terminated episodes of PSVT by reflexly increasing vagal drive. The magnitude of the rise in blood pressure was directly proportional to the depth of the inspired volume and to the extent of body dependency. The upright position attenuated the respiratory-induced increase in blood pressure and blocked PSVT termination. Likewise, vagal blockade with atropine did not affect the effects of respiration or dependent position on blood pressure but prevented termination of PSVT.PATIENTS with paroxysmal supraventricular tachycardia (PSVT) are encouraged to explore techniques to effect self-termination of the tachycardia." 2 Among the most common maneuvers are carotid sinus massage and the Valsalva maneuver.'-4 These methods are not always successful or especially easy to perform properly. Because some patients who suffer from PSVT report tachycardia termination from simpler maneuvers such as deep inspiration or a dependent body position we decided to investigate how these maneuvers might terminate PSVT. Our purpose was to define the mechanisms of action of these maneuvers and to delineate conditions in which they would be successful and those in which they might fail. Materials and MethodsEleven consecutive patients who suffered from PSVT for many years were selected for tlhis study (table 1). All had undergone extensive unsuccessful drug trials over a period of years. Characteristically, these patients had episodes of tachycardia that lasted for many hours without spontaneous termination and required multiple hospital visits for electroversion or treatment with potent vagal maneuvers. Although PSVT in all cases could be terminated by vagal techniques, none of these patients had ever tried to terminate PSVT by deep inspiration or by assuming a dependent body position. All patients were referred because they had requested a permanent atrial radio frequency pacemaker for self-termination of the arrhythmias.5' 6 In this context, we extensively explored the actions of respiration and body position on the tachycardia process.From the Department of Medicine, University of Toronto, and the Cardiovascular Unit, Toronto General Hospital, Toronto, Ontario, Canada. Supported in part by grants from the Ontario Heart Foundation and the Canadian Heart Foundation. The techniques used to explore the electrophysiologic character of PSVT and the suitability of a permanent radio frequency pacemaker to effect selfconversion have been extensively described."' 6Stimulating electrodes were placed in the right atrium and/or the right ventricle to initiate tachycardia. Aortic blood p...

Utility of transesophageal atrial pacing in the diagnostic evaluation of patients with unexplained syncope associated or not with palpitations

“…The study was performed in supine position. Previous studies have shown that the upright position markedly augmented the hypotension induced by the tachycardia [25]. More, vasovagal reaction noted in 15 of our patients can be also not specific and induced by the stressrelated to study or the isoproterenol infusion.…”

Effects of Continuous Enhanced Vagal Tone on Dual Atrioventricular Node and Accessory Pathways

“…[7][8][9][10][11][12] For patients with AVNRT, vagal enhancement can terminate the tachycardia either in anterograde slow or retrograde fast pathway. 12 .…”

“…[1][2][3][4][5][6][7][8][9][10][11][12] Sympathetic stimulation is commonly used to facilitate induction of these tachycardias, [1][2][3][4][5][6] whereas enhanced vagal tone by use of pharmacological or physical maneuvers is commonly used to terminate tachycardias. [7][8][9][10][11][12] However, in some patients, the onset of AV nodal reentrant tachycardia (AVNRT) occurs at times of presumed increased vagal tone, for example, during sleep or after sudden bending forward or squatting. The mechanism responsible for the tachycardia initiation is not known.…”

Electrophysiological Mechanisms and Determinants of Vagal Maneuvers for Termination of Paroxysmal Supraventricular Tachycardia

“…[1][2][3][4][5][6][7] Previous studies also showed that atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular reciprocating tachycardia (AVRT), which incorporate the atrioventricular (AV) node and accessory pathway (AP) within the circuit, can be interrupted by increasing the refractoriness of the AV node with vagal efferent stimulation; the response rate was related to the level of vagal reaction. 6 -12 Furthermore, Mehta et al 8 found that AVNRT had poorer response to vagal maneuvers than AVRT.…”