Background Little is known about the relationship between intrinsic cardiac nerve activity (ICNA) and spontaneous arrhythmias in ambulatory animals. Methods and Results We implanted radiotransmitters to record extrinsic cardiac nerve activity (ECNA, including stellate ganglion nerve activity, SGNA; vagal nerve activity, VNA) and ICNA (including superior left ganglionated plexi nerve activity, SLGPNA; ligament of Marshall nerve activity, LOMNA) in 6 ambulatory dogs. Intermittent rapid left atrial pacing was performed to induce paroxysmal atrial fibrillation (PAF) or atrial tachycardia (PAT). The vast majority (94%) of LOMNA were preceded or co-activated with ECNA (SGNA or VNA), whereas 6% of episodes were activated alone without concomitant SGNA or VNA. PAF and PAT were invariably (100%) preceded (<5 s) by ICNA. Most of PAT events (89%) were preceded by ICNA and sympathovagal co-activation, whereas 11% were preceded by ICNA and SGNA-only activation. Most of PAF events were preceded only by ICNA (72%); the remaining 28% by ECNA and ICNA together. Complex fractionated atrial electrograms (CFAEs) were observed during ICNA discharges that preceded the onset of PAT and PAF. Immunostaining confirmed the presence of both adrenergic and cholinergic nerve at ICNA sites. Conclusions There is a significant temporal relationship between ECNA and ICNA. However, ICNA can also activate alone. All PAT and PAF episodes were invariably preceded by ICNA. These findings suggest that ICNA (either alone or in collaboration with ECNA) is an invariable trigger of paroxysmal atrial tachyarrhythmias. ICNA might contaminate local atrial electrograms, resulting in CFAE-like activity.

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A WC ≥94 cm in males is independently associated with an increased prevalence of silent CAD. In patients with metabolic syndrome, this prevalence is increased by the presence of high WC.

Takotsubo cardiomyopathy predominantly occurs in women, with a high incidence in patients with psychiatric diseases. We present a 64-year-old white woman with an acute manic episode complicated by rhabdomyolysis and takotsubo cardiomyopathy.