Neuromodulatory Approaches for Atrial Fibrillation Ablation

In this review, the authors describe evolving alternative strategies for the management of AF, focusing on non-invasive and percutaneous autonomic modulation. This modulation can be achieved – among other approaches – via tragus stimulation, renal denervation, cardiac afferent denervation, alcohol injection in the vein of Marshall, baroreceptor activation therapy and endocardial ganglionated plexi ablation. Although promising, these therapies are currently under investigation but could play a role in the treatment of AF in combination with conventional pulmonary vein isolation in the near future.

Syncope caused by lymphomatous encasement of the internal carotid artery

We present a case of a 77-year-old man who reported 5 months of syncopal episodes. He was found to have diffuse large B-cell lymphoma encasing the left internal carotid artery but not impeding blood flow. The syncopal episodes resolved after his first cycle of chemotherapy. Recurrent syncope in non-cardiac lymphomas and other head and neck masses is exceedingly rare and may be due to reflex syncope prompted by carotid baroreceptor activation. There are 11 previously described cases of recurrent syncope associated with non-cardiac lymphoma. In all cases, lymphadenopathy abutting the carotid artery was present and the syncopal episodes resolved with treatment. Our case illustrates that malignancy should be considered in patients with unexplained recurrent syncope.

Recent advances in understanding and managing resistant/refractory hypertension

The management of resistant hypertension presents several challenges in everyday clinical practice. During the past few years, several studies have been performed to identify efficient and safe pharmacological and non-pharmacological options for the management of such patients. The Spironolactone versus placebo, bisoprolol, and doxazosin to determine the optimal treatment for drug-resistant hypertension (PATHWAY-2) trial demonstrated significant benefits with the use of spinorolactone as a fourth-line drug for the treatment of resistant hypertension over doxazosin and bisoprolol. In addition, recent data support that spironolactone may demonstrate superiority over central acting drugs in such patients, as well. Based on the European guidelines, spironolactone is recommended as the fourth-line drug option, followed by amiloride, other diuretics, doxazosin, bisoprolol or clonidine. Among several device-based approaches, renal sympathetic denervation had fallen into hibernation after the disappointing results of the Renal Denervation in Patients With Uncontrolled Hypertension (SYMPLICITY HTN) 3 trial. However, the technique re-emerged at the epicenter of the clinical and research interest after the favorable results of three sham-controlled studies, which facilitated novel catheters and techniques to perform the denervation. Significant results of iliac anastomosis on blood pressure levels have also been demonstrated. Nevertheless, the technique-related adverse events resulted in withdrawal of this interventional approach. Last, the sympatholytic properties of the carotid baroreceptor activation therapy were associated with significant blood pressure reductions in patients with resistant hypertension, which need to be verified in larger controlled trials. Currently device-based approaches are recommended only in the setting of clinical trials until more safety and efficacy data become available.

Smart Baroreceptor Activation Therapy Strikingly Attenuates Blood Pressure Variability in Hypertensive Rats With Impaired Baroreceptor

Increased blood pressure (BP) variability (BPV) is an independent risk factor of cardiovascular events among hypertensive patients. The arterial baroreceptor reflex is a powerful regulator of BP and attenuates BPV via a sympathetic negative feedback control. Conventional baroreceptor activation therapy (cBAT) electrically stimulates the carotid baroreceptors with constant stimulation parameters. While cBAT lowers BP, it does not mount a pressure feedback mechanism. We hypothesized that baroreceptor activation therapy with a pressure feedback system (smart BAT [sBAT]) is able to reduce BPV as well as lower BP. We developed sBAT that electrically stimulated baroreceptors at a frequency proportional to the difference between instantaneous BP and a preset reference pressure, and compared its performance with cBAT. In 14-week-old spontaneously hypertensive rats (n=6), we implanted BP telemeter and created impaired arterial baroreceptors by modified sino-aortic denervation. One week after surgical preparation, we administered sBAT, cBAT or no stimulation (sham) for 15 minutes and compared BP and BPV under freely moving condition. Both cBAT and sBAT significantly lowered mean BP (sham, 141.3±12.8; cBAT, 114.3±11.4; and sBAT, 112.0±7.3 mm Hg). Conventional BAT did not affect BPV at all, while sBAT significantly reduced BPV (sham, 15.4±2.6; cBAT, 16.0±5.2; and sBAT, 9.7±3.3 mm Hg). sBAT also prevented transient excessive BP rise and fall. In conclusion, sBAT was capable of reducing BP and attenuating BPV in hypertensive rats with impaired baroreceptor. sBAT is a novel treatment option for hypertensive patients with increased BPV.

Role of the Kölliker-Fuse nucleus in cardiovascular responses to hypoxia and baroreceptor activation in anesthetized rats

<span style="color: #1f497d;">Introduction: Parabrachial Kölliker-Fuse (KF) complex, located in dorsolateral part of the pons, is involved in the respiratory control, however, its role in the baroreflex and chemoreflex responses has not been established yet. This study was performed to test the contribution of the KF to chemoreflex and baroreflex and the effect of microinjection of a reversible synaptic blocker (Cocl2) into the KF in urethane anesthetized rats. <br /> <span style="color: #1f497d;">Methods: Activation of chemoreflex was induced by systemic hypoxia caused by N2 breathing for 30 seconds "hypoxic- hypoxia methods" and baroreflex was evoked by intravenous injection (i.v.) of phenylephrine (Phe, 20 µg /kg/0.05–0.1 mL). N2 induced generalized vasodilatation followed by tachycardia reflex and Phe evoked vasoconstriction followed by bradycardia.<br /> <span style="color: #1f497d;">Results: Microinjection of Cocl2 (5 mM/100 nL/side) produced no significant changes in the Phe-induced hypertension and bradycardia, whereas the cardiovascular effect of N2 was significantly attenuated by the injection of CoCl2 to the KF. <br /> <span style="color: #1f497d;">Conclusion: The KF played no significant role in the baroreflex, but could account for cardiovascular chemoreflex in urethane anesthetized rats.