Paper
Friday, July 23, 2004
10:00 AM - 10:30 AM
Friday, July 23, 2004
3:00 PM - 3:30 PM
Autonomic Nervous System Tone in Genetically Inherited Sudden Cardiac Death
Kathleen S. Stone, PhD, RN, FAAN, College of Nursing, The Ohio State University, Columbus, OH, USA, Matthew D. Stone, N/A, Premedicine, Calvin College, Grand Rapids, MI, USA, Elizabeth Sparks, BS, MS, Division of Cardiology, The Ohio State University, Columbus, OH, USA, and Debra K. Moser, DNSc, RN, College of Nursing, University of Kentucky, Lexington, KY, USA.
Introduction: Prolonged P-R is an autosomal dominant (chromosome 1p1-1q1 progressive disorder that alters atrio-ventricular (A-V) conduction resulting in bradycardia, A-V block,and sudden cardiac death (SCD). Prolonged Q-T syndrome (Romano-Ward Syndrome) is an autosomal dominant (Chromosomes 3,7,11,21) condition with QTc>0.48 seconds resulting in syncope, seizures and SCD. Physical exertion, emotional events and loud noises are associated with SCD episodes and may be due to altered autonomic nervous system (ANS) tone with increased sympathetic tone predominating. ANS tone has not been previously examined in subjects in genetically inherited SCD. Heart Rate Variability (HRV) is a valid non-invasive measure of ANS tone. Increased sympathetic tone decreases heart rate variability and increases risk for SCD. Objective: This study examined autonomic nervous sytem tone in subjects with prolonged P-R or prolonged QT syndrome. Design: Descriptive design Population: 3-groups (P-R n=7, Q-T n=5, Normal n=6) age and sex matched. Methods: Ambulatory 24-hour electrocardiographic Holter monitoring was conducted. Holter tapes were analyzed using a Zymed 1510 in sem-automatic mode with operator confirmation of all beat types. Findings: Time domain analysis using the standard deviation of R-R intervals revealed means± s.d. for P-R 153.6±44.2, QT 116± 37, Normals 132± 35. Heart rate variability in the Q-T group had lower s.d. values compared to the normal group. Poincare plots were constructed from sinus R-R intervals by plotting each R-R interval versus the following R-R interval. Poincare analysis revealed P-R (5/7 or 71% abnormal), Q-T(4/5 or 80% abnormal), Normals (1/6 or 16% abnormal). Conclusions: Subjects with prolonged P-R or Q-T syndrome may have decreased HRV indicative of increased sympathetic tone thereby increasing the risk for SCD episodes. Implications: Non-invasive HRV measurement may be useful in identifying prolonged P-R or Q-T syndrome patients who are at risk for SCD. Funding: American Association of Critical Care Nurses
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