Cardiac autonomic innervation.

The autonomic nervous system plays a key role in regulating changes in the cardiovascular system and its adaptation to various human body functions. The sympathetic arm of the autonomic nervous system is associated with the fight and flight response, while the parasympathetic division is responsible for the restorative effects on heart rate, blood pressure, and contractility. Disorders involving these two divisions can lead to, and are seen as, a manifestation of most common cardiovascular disorders. Over the last few decades, extensive research has been performed establishing imaging techniques to quantify the autonomic dysfunction associated with various cardiovascular disorders. Additionally, several techniques have been tested with variable success in modulating the cardiac autonomic nervous system as treatment for these disorders. In this review, we summarize basic anatomy, physiology, and pathophysiology of the cardiac autonomic nervous system including adrenergic receptors. We have also discussed several imaging modalities available to aid in diagnosis of cardiac autonomic dysfunction and autonomic modulation techniques, including pharmacologic and device-based therapies, that have been or are being tested currently.

Idiopathic Atrial Fibrillation and Coronary Arteriovenous Fistulae: Is There a Link.

Despite being one of the most prevalent cardiac arrhythmias, the cause of atrial fibrillation (AF) in a vast majority of patients remains unknown. There is growing evidence of associated AF in patients diagnosed with coronary arteriovenous fistula. In this discussion, we have included an example of a patient who presented with new-onset AF and was subsequently diagnosed with an anomalous fistula between the right coronary artery and the superior vena cava. Definitive treatment of the fistula resulted in permanent resolution of the AF. Based on this case and a similar case reported in the literature, it is proposed that further research will unmask this possibly underdiagnosed and very treatable cause of AF.

Cardiac Tamponade Physiology Secondary to Tense Ascites.

Cardiac tamponade is a common and often life-threatening process, which is typically associated with a pericardial effusion or, in rare cases, with a large pleural effusion. Theoretically, as reported in only a single prior case, it can be caused by extrinsic compression from tense ascites. We present a case in which dynamic inferior wall collapse was secondary to increased abdominal pressure from tense ascites. This phenomenon may be more common than previously diagnosed, especially in patients with liver disease. These patients often develop frequent ascites and present with clinical signs and symptoms similar to cardiac tamponade (tachycardia, hypotension and dyspnea). Presently, no formal practice guidelines exist regarding cardiac imaging for these patients. A high index of suspicion is required for timely diagnosis and management.