Psychophysiologic and affective parameters associated with pain intensity of cardiac cardioverter defibrillator shock discharges.
OBJECTIVE
Pain caused by intracardiac shock discharge of an implanted cardioverter defibrillator (ICD) is an important clinical issue in the treatment of ICD patients. The present study aimed to examine whether the strength of perceived shock pain is influenced by affective and psychophysiologic parameters.


METHODS
Among 204 ICD patients drawn from the German Heart Center Munich, 95 patients (46.6%) experienced > or =1 shock discharge. Pain perception (PPC) was measured by a visual analog scale ranged from 0 to 100 points. Standard instruments were administered to measure psychological distress. A startle paradigm was assessed to measure psychophysiologic arousal with skin conductance responses (SCR) and electromyogram responses (EMG) as dependant variables. Classification and regression tree (CART) analysis was applied to assess the effects of psychodiagnostic and psychophysiologic parameters on pain perception.


RESULTS
Mean ICD shock PPC was 53.7 points (SD 31.6), with a median of 59.0 points (interquartile range 30-80). Pain intensity was highly associated with shock discomfort (p < .001) but was largely uninfluenced by clinical and sociodemographic factors. CART analysis revealed patients with one shock and low EMG magnitude (< or =4.15 muV) as subclass with the lowest mean PPC (21.9 points; 95% confidence interval [CI], 4.6-39.1), whereas patients with >one shock experience and an anxiety score >7 (Symptom Checklist-90) expressed the highest mean PPC (74.8 points; 95% CI, 60.5-89.2). Without heightened anxiety, an increased EMG amplitude and impaired EMG habituation yielded a mean PPC of 71.2 (95% CI, 61.6-80.9).


CONCLUSIONS
Augmented PPC of ICD shocks is predominantly associated with the number of perceived shocks, postshock anxiety, and accompanied by heightened levels of EMG magnitude and impaired EMG habituation, which points to sensitization of central neural structures.
Baumert
Jens
J
Klinik und Poliklinik für Psychosomatische Medizin, Psychotherapie und Medizinische Psychologie, Klinikum rechts der Isar der Technischen Universität München, Munich, Germany.
Schmitt
Claus
C
Ladwig
Karl-Heinz
KH
D000161:Acoustic Stimulation; D001008:Anxiety Disorders / Q000175:diagnosis*; D017147:Defibrillators, Implantable / Q000009:adverse effects*; D003866:Depressive Disorder / Q000175:diagnosis; D004554:Electric Countershock / Q000009:adverse effects*; D004576:Electromyography; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology*; D006185:Habituation, Psychophysiologic / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000175:diagnosis* / Q000209:etiology*; D010147:Pain Measurement / Q000706:statistics & numerical data; D010555:Personality Inventory; D011569:Psychiatric Status Rating Scales; D013216:Reflex, Startle / Q000502:physiology*; D013315:Stress, Psychological / Q000175:diagnosis / Q000209:etiology / Q000523:psychology; D017180:Tachycardia, Ventricular / Q000628:therapy