The purpose of this study is to characterize the behavior of cardiac patients with Mood Disorders and its clinical course, interpreting the results from a theoretical framework of Chaos Theory and Complexity Theory and Systems as well.

Mood disorders are strongly associated with changes in cardiovascular function and alterations in Hear Rate Variability (HRV). Fluctuation in heart rate occurs over a wide frequency and demonstrates a broad, irregular variability that suggests that the mechanisms involved in cardiovascular regulation interact in a nonlinear manner. Over the past decade, there has been an increasing emphasis on applying nonlinear methods of analysis to characterize cardiac function, but the studies on the pathophysiology of mood disorders in general still remain under a linear and reductionist perspective. The scarcity of both Brazilian and international studies on the autonomic behavior in mood disorders in general and not only in Major Depressive Disorder, as well as the use of a non-linear reading of the results of this study makes an additional tool of analysis.

Inclusion Criteria:

• Clinical diagnosis of Bipolar Disorder (BD) or Major Depressive Disorder(MDD)

Exclusion Criteria:

• Another with criteria for Axis I or II disorders aside from the primary diagnosis of BD or MDD.
• Past history of stroke, heart attack, or cardiac disease.
• Drug abuse or dependence in the past six months.
• Diabetes.
• In use of Tricyclic Antidepressants

Acutely hospitalized patient and in ambulatorial attendance with Bipolar Disorder or Major Depressive Disorder.