Carotid sinus syndrome: Progress in understanding and management

Carotid Sinus Syndrome With Convulsive Syncope in a Patient With Head and Neck Cancer

This case report provides a comprehensive overview of a unique case of a 64-year-old male patient with head and neck (H&N) cancer who initially presented with compressive convulsive syncope, an initial manifestation of carotid sinus syndrome (CSS). CSS is an autonomic nervous system disease that often manifests as hypotension, dizziness, cerebral ischemia, or syncope, usually in elderly patients. In this case, the patient's laryngeal cancer led to lymphedema and encasement of the bilateral carotid arteries, inducing CSS and resulting in recurrent episodes of hypotension and bradycardia. These symptoms were managed through the administration of atropine and transcutaneous pacemaker placement, suggesting a probable mixed type of CSS. The patient was discharged on long-term theophylline treatment for symptomatic control of bradycardia episodes. Despite the promising outcomes of CSS cases treated with pacemakers, the efficacy is not universal and limitations may arise, particularly in H&N cancer patients. Therefore, the patient was managed with theophylline rather than a pacemaker due to its non-invasiveness and effectiveness in temporarily managing CSS. Although rare, CSS should be considered in patients experiencing convulsive syncope alongside H&N malignancies. As the evidence and consensus regarding CSS treatment in H&N cancer patients are scarce, additional research is necessary to evaluate and compare available options. This abstract concludes by emphasizing the need for further research and case reports to establish a consensus on the optimal management approach for patients affected by CSS due to compression from H&N cancers.

Carotid Sinus Tumor-Induced Positional Bradycardia and Hypotension After Extubation: A Case Report

Regional progression of head and neck malignancies can lead to carotid sinus tumors, causing hemodynamic instability and carotid sinus syndrome (CSS). A 60-year-old male with tonsillar squamous cell carcinoma developed profound positional bradycardia and hypotension immediately after extubation following dental extraction. The patient developed recurrent episodes of positional bradycardia and hypotension, leading to eventual pacemaker placement. Further workup revealed a large mass in the left neck and necrotic cervical lymphadenopathy, indicating CSS from malignancy compression. This case highlights the need for consideration of CSS in patients with known head and neck malignancy, particularly when postural hypotension and bradycardia are present.

Air Pollution Role as Risk Factor of Cardioinhibitory Carotid Hypersensitivity

Little is known about the impact of air pollution on neuroautonomic system. The authors have investigated possible influence of air pollution and outdoor temperature on the carotid sinus hypersensitivity (CSH), as main cause of neurally mediated syncope in forty-years-old subjects and older. Pollutants’ concentrations and outdoor temperature of days in which 179 subjects with recurrent syncope underwent carotid sinus massage (CSM) were analyzed. Before this manoeuvre, cardiovascular control by short period heart and blood pressure spectral duration of segment between the end of P and R ECG-waves (PeR) were registred; RR variability on the same short period ECG recordings and their spectral coherence were also analyzed. CSH was found in 57 patients (28 with cardioinhibitory response and 29 subjects showed vasodepressor reaction), while 122 subjects had a normal response. CSM performed during high ozone concentrations was associated with slightly higher risk of cardioinhibitory response (odd ratio 1.012, 95% CI 1.001–1.023, p < 0.05), but neither this or other polluting agent nor outdoor temperature seemed to influence autonomic control in basal resting condition. Thus, ozone seemed to influence response to the CSM in CSH patients and it is probably able to facilitate a cardioinhibitory response, perhaps through an increase of nerve acetylcholine release. P→PR coherence could be useful in predicting a sinus cardioinhibitory hypersensitivity in those cases when CSM is contraindicated.

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.

Should We Ever Pace for Carotid Sinus Syndrome?

Carotid sinus syndrome has been associated with transient loss of consciousness for millennia, and while steeped in cardiovascular lore, there is little in the way of solid evidence to guide its main treatment modality, permanent cardiac pacing. This article reviews the history of the condition in the context of its contemporary understanding before examining three key concepts in the consideration of what constitutes a manageable disease: first, is there a pathophysiologic rationale for the disease (in this case carotid sinus syndrome)? Second, is there a good diagnostic test that will identify it reliably? And finally, is there a convincingly evidence-based treatment for the disease? Relevant literature is reviewed, and recommendations made in how we view pacing in the context of this intriguingly opaque condition.

Carotid Sinus Syndrome in a Patient with Head and Neck Cancer: A Case Report

Syncope is a common complaint among patients presenting to the emergency department. Its differential diagnosis is broad and its management varies significantly depending on the underlying etiology. This is especially complex in patients with head and neck cancer since it may appear as an initial manifestation of the disease, as a side effect of surgery or radiotherapy, or as an indicator of local recurrence. Carotid sinus syndrome is a rare disease, whose pathophysiology is not yet fully understood. Here, we present the rare case of a 79-year-old male patient with a left cervical lymph node metastasis from an occult primary malignancy, who was admitted due to recurrent syncope. Paroxysms of extreme bradycardia were detected and a definitive dual chamber pacemaker was placed; however, the patient remained symptomatic. Cervical CT-scan revealed incarceration and compression of the left carotid sinus. The patient underwent radiotherapy, with favourable response, and remains asymptomatic to date.

New onset syncopal events following vagus nerve stimulator implantation might be key to preventing vagus nerve stimulation-induced symptomatic bradycardia - A case report and review

PURPOSE

To identify risk factors for VNS-associated arrhythmia.

METHODS

A literature review identified 14 papers with 21 patients. We compared patients with VNS associated arrhythmia (arrhythmia group, n = 22) and patients without VNS associated arrhythmia (control group of our VNS implanted patients, n = 29).

RESULTS

New onset syncopal events following VNS placement were seen in the arrhythmia group (p < 0.001).

CONCLUSION

Even though arrhythmia could be symptomatic, most cases associated with syncope were treated as new-onset epileptic seizures with adjustment of anti-seizure drugs. To detect cardiac asystole during VNS treatment, clinicians should be alert to the possibility of new onset syncopal events that differ from habitual seizures.

Carotid sinus hypersensitivity: block of the sternocleidomastoid muscle does not affect responses to carotid sinus massage in healthy young adults

The arterial baroreflex is crucial for short‐term blood pressure control – abnormal baroreflex function predisposes to syncope and falling. Hypersensitive responses to carotid baroreflex stimulation using carotid sinus massage (CSM) are common in older adults and may be associated with syncope. The pathophysiology of this hypersensitivity is unknown, but chronic denervation of the sternocleidomastoid muscles is common in elderly patients with carotid sinus hypersensitivity (CSH), and is proposed to interfere with normal integration of afferent firing from the carotid baroreceptors with proprioceptive feedback from the sternocleidomastoids, producing large responses to CSM. We hypothesized that simulation of sternocleidomastoid “denervation” using pharmacological blockade would increase cardiovascular responses to CSM. Thirteen participants received supine and tilted CSM prior to intramuscular injections (6–8 mL distributed over four sites) of 2% lidocaine hydrochloride, and 0.9% saline (placebo) in contralateral sternocleidomastoid muscles. Muscle activation was recorded with electromyography (EMG) during maximal unilateral sternocleidomastoid contraction both pre‐ and postinjection. Supine and tilted CSM were repeated following injections and responses compared to preinjection. Following lidocaine injection, the muscle activation fell to 23 ± 0.04% of the preinjection value (P < 0.001), confirming neural block of the sternocleidomastoid muscles. Cardiac (RRI, RR interval), forearm vascular resistance (FVR), and systolic arterial pressure (SAP) responses to CSM did not increase after lidocaine injection in either supine or tilted positions (supine: ΔRRI −72 ± 31 ms, ΔSAP +2 ± 1 mmHg, ΔFVR +4 ± 4%; tilted: ΔRRI −20 ± 13 ms, ΔSAP +2 ± 2 mmHg, ΔFVR +2 ± 4%; all P > 0.05). Neural block of the sternocleidomastoid muscles does not increase cardiovascular responses to CSM. The pathophysiology of CSH remains unknown.

Neurocardiovascular Instability and Cognition

Neurocardiovascular instability (NCVI) refers to abnormal neural control of the cardiovascular system affecting blood pressure and heart rate behavior. Autonomic dysfunction and impaired cerebral autoregulation in aging contribute to this phenomenon characterized by hypotension and bradyarrhythmia. Ultimately, this increases the risk of falls and syncope in older people. NCVI is common in patients with neurodegenerative disorders including dementia. This review discusses the various syndromes that characterize NCVI icluding hypotension, carotid sinus hypersensitivity, postprandial hypotension and vasovagal syncope and how they may contribute to the aetiology of cognitive decline. Conversely, they may also be a consequence of a common neurodegenerative process. Regardless, recognition of their association is paramount in optimizing management of these patients.