Distribution of cardiac nerves in patients with diabetes mellitus: an immunohistochemical postmortem study of human hearts

Cardiac innervation and sudden cardiac death

The heart is extensively innervated and its performance is tightly controlled by the nervous system. Cardiac innervation density varies in diseased hearts leading to unbalanced neural activation and lethal arrhythmia. Diabetic sensory neuropathy causes silent myocardial ischemia, characterized by loss of pain perception during myocardial ischemia, which is a major cause of sudden cardiac death in diabetes mellitus (DM). Despite its clinical importance, the mechanisms underlying the control and regulation of cardiac innervation remain poorly understood.We found that cardiac innervation is determined by the balance between neural chemoattractants and chemorepellents within the heart. Nerve growth factor (NGF), a potent chemoattractant, is induced by endothelin-1 upregulation during development and is highly expressed in cardiomyocytes. By comparison, Sema3a, a neural chemorepellent, is highly expressed in the subendocardium of early stage embryos, and is suppressed during development. The balance of expression between NGF and Seme3a leads to epicardial-to-endocardial transmural sympathetic innervation patterning. We also found that downregulation of cardiac NGF leads to diabetic neuropathy, and that NGF supplementation rescues silent myocardial ischemia in DM. Cardiac innervation patterning is disrupted in Sema3a-deficient and Sema3a-overexpressing mice, leading to sudden death or lethal arrhythmias. The present review focuses on the regulatory mechanisms underlying cardiac innervation and the critical role of these processes in cardiac performance.

The clinical features of transient left ventricular nonapical ballooning syndrome: comparison with apical ballooning syndrome

BACKGROUND

Recently, several cases of atypical left ventricular (LV) ballooning syndrome without involvement of the LV apex have been reported. However, there has been no assessment of the clinical features of this novel presentation or comparison with the typical transient LV apical ballooning syndrome.

METHODS

We evaluated 47 patients diagnosed with transient LV ballooning syndrome. The diagnostic criteria were (1) transient akinesia/dyskinesia beyond a single major coronary artery vascular distribution, (2) absence of significant coronary artery disease on coronary angiograms, and (3) new electrocardiographic changes.

RESULTS

Thirty-one patients showed classic LV apical ballooning, and 16 showed atypical LV ballooning without involvement of the LV apex (nonapical ballooning). Clinical presentations and inhospital courses of illness were mostly similar among patients with nonapical ballooning (group NA) and patients with apical ballooning (group A). However, on admission, there were fewer patients with cardiogenic shock or pulmonary edema in group NA than in group A (19% vs 48%, P = .048). Group NA patients were relatively younger than group A patients (median ages 58 vs 70 years, P = .02), and fewer patients had coronary risk factors in group NA than in group A (38% vs 77%, P = .01). On electrocardiogram, T-wave inversion was noted less frequently in the NA group than in the A group (69% vs 97%, P = .01).

CONCLUSIONS

Transient LV nonapical ballooning syndrome and classic LV apical ballooning syndrome may be different manifestations of a single syndrome. They appear to have differences in the severity of heart failure, in patient characteristics, and in electrocardiographic change.

ORIGINAL RESEARCH—BASIC SCIENCE: A Prospective Study Examining the Anatomic Distribution of Nerve Density in the Human Vagina

INTRODUCTION

Women possess sufficient vaginal innervation such that tactile stimulation of the vagina can lead to orgasm. However, there are few anatomic studies that have characterized the distribution of nerves throughout the human vagina.

AIM

The aim of this prospective study was to better characterize the anatomic distribution of nerves in the adult human vagina. A secondary aim was to assess whether vaginal innervation correlates with the subject's demographic information and sexual function.

METHODS

Full-thickness biopsies of anterior and posterior vagina (proximal and distal), cuff, and cervix were taken during surgery in a standardized manner. Specimens were prepared with hematoxylin and eosin, and S100 protein immunoperoxidase. The total number of nerves in each specimen was quantified. Enrolled patients completed a validated sexual function questionnaire (Female Sexual Function Index, FSFI) preoperatively.

MAIN OUTCOME MEASURES

A description of vaginal innervation by location and an assessment of vaginal innervation in association with the subject's demographic information and sexual function.

RESULTS

Twenty-one patients completed this study, yielding 110 biopsy specimens. Vaginal innervation was somewhat regular, with no site consistently demonstrating the highest nerve density. Nerves were located throughout the vagina, including apex and cervix. No significant differences were noted in vaginal innervation based on various demographic factors, including age, vaginal maturation index, stage of prolapse, number of vaginal deliveries, or previous hysterectomy. There were no correlations between vaginal nerve quantity and FSFI domain and overall scores. Fifty-seven percent of the subjects had female sexual dysfunction; when compared to those without dysfunction, there were no significant differences in total or site-specific nerves.

CONCLUSIONS

In a prospective study, vaginal nerves were located regularly throughout the anterior and posterior vagina, proximally and distally, including apex and cervix. There was no vaginal location with increased nerve density. Vaginal innervation was not associated with demographic information or sexual function.