Dr. Lucio Montebugnoli and colleagues are to be congratulated for their December JADA article, "Heart Rate Variability: A Sensitive Parameter for Detecting Abnormal Cardiocirculatory Changes During a Stressful Dental Procedure." Clinical studies are time-consuming, difficult to administer and usually challenging for any of a number of reasons. Their study is certainly a terrific beginning for the clinical evaluation of heart rate variability as a measure of clinical patient safety. However, their study is only an initial peek into the feasibility of heart rate variability as a predictor of morbidity and mortality with relevance to clinical dentistry.
Their study demonstrated that heart rate variability showed significance between basal, postanesthesia, extraction and recovery time point measurements compared with heart rate, which showed significance at only two time points, and systolic and diastolic blood pressure, which did not demonstrate significance between time points. The real question is whether or not these results are meaningful, repeatable and clinically relevant. Hopefully, time will tell.
The authors quoted Lawler and colleagues1 with regard to six hemodynamic reactor patterns (nonreactors, mild myocardials, mild vasculars, myocardials, vasculars and dual reactors). However, Lawler evaluated subjects undergoing such stressors as mental arithmetic and anger as opposed to pain. There is as yet no confirmation that these differing cardioreactivity patterns translate to the clinical practice of dentistry. Schneider and colleagues,2 in examining cardiovascular hemodynamic response to mental stress, determined that a family history positive for hypertension was predictive of increased cardiac output reactivity. Furthermore, the response of the parasympathetic nervous system is not unidimensional. Pump and colleagues3 noted that the carotid baroreceptors’ adaptation may be subject to postural change and central volume expansion.
Also, Dr. Montebugnoli and colleagues’ subjects had an age range of between 19 and 73 years, and their family history of hypertension was not defined. Matsumura and colleagues4 evaluated changes in blood pressure and heart rate variability during dental surgery, and concluded that the regulation of the autonomic nervous system differs between middle-aged and older patients compared with younger patients. Furthermore, Nakamura and colleagues,5 in evaluating cardiovascular and sympathetic responses to dental surgery with local anesthesia, concluded that ambulatory measurements of blood pressure and heart rate variability over 24 hours cannot predict the response of blood pressure during dental surgery.
Miura and colleagues,6 in examining the suppression of the cardiac sympathetic nervous system during dental surgery in hypertensive patients, suggested that the pressor response induced by tooth extraction did not differ between normotensive and hypertensive patients.
Because of the many complicated physiological concerns related to mental stress, pain stress, carioreactivity, multiple blood pressure controls and postural issues, the utilization of heart rate variability as a measure for the determination of clinical risk in the practice of dentistry has a long way to go. Nonetheless, initial human studies are extremely difficult to perform, and Dr. Montebugnoli and colleagues are to be congratulated for publishing an excellent study, as well as for introducing heart rate variability as having the potential to influence the safety of dental patients in the future.
TOP
REFERENCES
