Arterial baroreflex and peripheral chemoreflex function after radiotherapy for laryngeal or pharyngeal cancer

Physiological and clinical impact in the carotid baroreceptor function following the surgical management of bilateral carotid body tumors

OBJECTIVE

The bilateral presentation of Carotid Body Tumors (CBT) is rare; the surgical resection of these masses remains the mainstay management due to the malignant potential. We aim to describe, classify, and quantify baroreceptor failure (BRF) after the surgical management of patients with bilateral CBT to better understand the clinical consequences.

METHODS

Retrospective review of patients that underwent bilateral CBT resection to assess the changes in baroreceptor function. We describe the clinical events associated to BRF after surgery, baseline patient's demographics, characteristics, comorbidities. Additionally, clinical and a quantitative evaluation of baroreceptor sensitivity were conducted using the Composite Autonomic Severity Score (CASS).

RESULTS

From 1986 to 2020, a total 146 CBT resections were performed in 132 patients in our institution. Tumors were removed bilaterally in staged procedures in seven patients with a mean age of 61 years (Standard Deviation 11), six (85%) were females, and there was no family history of paragangliomas. The clinical presentation were palpable masses in 5 (71%), and odynophagia in 2 (29%) cases; malignant histopathology following surgery was found in one case. BRF occurred in one patient after unilateral CBT resection, consisting of bradycardia and a 40 s asystole that was not previously associated to BR sensitivity. Three (43%) patients presented BRF in the immediate postoperative period of the contralateral CBT excision, consisting of volatile hypertensive crisis in two cases, and supraventricular tachycardia in one. All the patients developed (100%) chronic baroreceptor sensitivity symptoms consisting in syncope, vertigo and fatigue in 4 (57%), tachycardia in 2 (28%), and orthostatic headache in one (14%). Autonomic testing showed mixed sympathetic and parasympathetic failure in five (71%), severe sympathetic failure in 1 (14%), and parasympathetic dysfunction in one patient (14%).

CONCLUSIONS

Postoperative autonomic assessment confirmed BRF in all studied patients that underwent staged bilateral CBT resection with mixed, sympathetic, and parasympathetic dysfunction. Further studies are necessary to evaluate the incidence and physiological mechanisms of these sequelae to anticipate possible complications and offer the appropriate perioperative management.

Excision of massive left branchial cleft cyst with secondary hypertension

Branchial anomalies are heterogeneous congenital malformations that form secondary to incomplete closure of pharyngeal clefts and pouches. There have been no reports of branchial cleft cysts causing carotid artery compression and hypertension. We report a large branchial cleft cyst causing suspected secondary hypertension from carotid artery compression.

Standardized Autonomic Testing in Patients With Probable Radiation-Induced Afferent Baroreflex Failure

Injury of the afferent limb of the baroreflex from neck radiation causes radiation-induced afferent baroreflex failure (R-ABF). Identification and management of R-ABF is challenging. We aimed to investigate the pattern of autonomic dysfunction on standardized autonomic testing in patients with probable R-ABF. We retrospectively analyzed all autonomic reflex screens performed at Mayo Clinic in Rochester, MN, between 2000 and 2020 in patients with probable R-ABF. Additional tests reviewed included ambulatory blood pressure monitoring, plasma norepinephrine, and thermoregulatory sweat test. We identified 90 patients with probable R-ABF. Median total composite autonomic severity score (range, 0-10) was 7 (interquartile range, 6-7). Cardiovascular adrenergic impairment was seen in 85 patients (94.4%), increased blood pressure recovery time after Valsalva maneuver in 71 patients (78.9%; median 17.4 seconds), and orthostatic hypotension in 68 patients (75.6%). Cardiovagal impairment was demonstrated by abnormal heart rate responses to deep breathing (79.5%), Valsalva ratio (87.2%), and vagal baroreflex sensitivity (57.9%). Plasma norepinephrine was elevated and rose appropriately upon standing (722-1207 pg/mL). Ambulatory blood pressure monitoring revealed hypertension, postural hypotension, hypertensive surges, tachycardia, and absence of nocturnal dipping. Blood pressure lability correlated with impaired vagal baroreflex function. Postganglionic sympathetic sudomotor function was normal in most cases; the most frequent thermoregulatory sweat test finding was focal neck anhidrosis (78.9%). Standardized autonomic testing in R-ABF demonstrates cardiovascular adrenergic impairment with orthostatic hypotension, blood pressure lability, and elevated plasma norepinephrine. Cardiovagal impairment is common, while sudomotor deficits are limited to direct radiation effects.

Natural History of Afferent Baroreflex Failure in Adults

OBJECTIVE

To describe the natural history of afferent baroreflex failure (ABF) based on systematic review of clinical and laboratory data in patients with a diagnosis of ABF at Mayo Clinic Rochester.

METHODS

We performed a retrospective chart review of all patients who underwent standardized autonomic reflex testing between 2000 and 2020 and had confirmation of the diagnosis of ABF by an autonomic disorders specialist. Patients were identified using a data repository of medical records. Variables included demographic, all-cause mortality, medications, ABF manifestations, comorbidities, and laboratory (autonomic testing, blood pressure monitoring, echocardiogram, brain imaging, plasma catecholamines, serum sodium level, and kidney function tests).

RESULTS

A total of 104 patients with ABF were identified. Head and neck radiation was the most common etiology (86.5%), followed by neck surgery (5.8%) and other causes (7.7%). The most common findings were hypertension (87.5%), fluctuating blood pressure (78.8%), orthostatic hypotension (91.3%), syncope (58.6%), headache (22.1%), and tachycardia (20.2%). Patients commonly received antihypertensives (66.3%), pressor agents (41.3%), or a combination of both (19.2%). The median latency from completion of radiation to ABF was longer compared to the latency in the surgery group (p < 0.0001). Comorbidities, including complications from neck radiation, were frequently seen and all-cause mortality was 39.4% over a 20-year period.

CONCLUSIONS

ABF should be suspected in patients with prior head and neck cancer treated by radiation or surgery who present with labile hypertension and orthostatic hypotension. Management may require both antihypertensive and pressor medications. The morbidity and mortality in ABF are high.

Hypertensive Cardiotoxicity in Cancer Treatment-Systematic Analysis of Adjunct, Conventional Chemotherapy, and Novel Therapies-Epidemiology, Incidence, and Pathophysiology

Cardiotoxicity is the umbrella term for cardiovascular side effects of cancer therapies. The most widely recognized phenotype is left ventricular dysfunction, but cardiotoxicity can manifest as arrhythmogenic, vascular, myocarditic and hypertensive toxicities. Hypertension has long been regarded as one of the most prevalent and modifiable cardiovascular risk factors in the general population, but its relevance during the cancer treatment journey may be underestimated. Hypertensive cardiotoxicity occurs de novo in a substantial proportion of treated cancer patients. The pathology is incompletely characterized—natriuresis and renin angiotensin system interactions play a role particularly in conventional treatments, but in novel therapies endothelial dysfunction and the interaction between the cancer and cardiac kinome are implicated. There exists a treatment paradox in that a significant hypertensive response not only mandates anti-hypertensive treatment, but in fact, in certain cancer treatment scenarios, hypertension is a predictor of cancer treatment efficacy and response. In this comprehensive review of over 80,000 patients, we explored the epidemiology, incidence, and mechanistic pathophysiology of hypertensive cardiotoxicity in adjunct, conventional chemotherapy, and novel cancer treatments. Conventional chemotherapy, adjunct treatments, and novel targeted therapies collectively caused new onset hypertension in 33–68% of treated patients. The incidence of hypertensive cardiotoxicity across twenty common novel therapies for any grade hypertension ranged from 4% (imatinib) to 68% (lenvatinib), and high grade 3 or 4 hypertension in <1% (imatinib) to 42% (lenvatinib). The weighted average effect was all-grade hypertension in 24% and grade 3 or 4 hypertension in 8%.

Severe impaired blood pressure control caused by baroreflex failure as a late sequela of neck irradiation

: A 64-year-old man, whose medical history was significant only for locally advanced squamocellular carcinoma of the right palatine tonsil treated with extended neck radiotherapy 9 years before, was evaluated for traumatic cerebral haemorrhage secondary to syncope after a postural change. The selective angiographic study of cerebral vessels was negative. No heart arrhythmias were recorded at ECG monitoring. The 24-h ABPM revealed sudden pressor and depressor episodes during day-time and a reverse dipper pattern during night-time. Noninvasive autonomic nervous system function testing showed supine hypertension and orthostatic hypotension caused by afferent baroreflex failure. According to literature, even if only few cases are described, neck irradiation can be assumed to be the major cause of baroreflex failure. No treatment is currently approved. The patient was treated with a selective beta-blocker (bisoprolol) administered at bedtime. Repeated ABPM after 1 month of therapy showed absence of sudden pressor and depressor episodes and no dipper pattern during night-time.

General Anesthesia Imposes Negative Effects on Heart Rate and Blood Pressure Regulation in Patients With a History of Head and Neck Radiation Therapy

BACKGROUND

Head and neck radiation therapy (HNRT) impairs baroreflex sensitivity, and it may potentiate the effects of anesthetics on heart rate (HR) and blood pressure (BP) regulation. Currently, the impacts of HNRT on HR and BP under anesthesia remain unclear.

METHODS

In this study, 472 patients with primary oral cavity or oropharyngeal cancer at all stages were examined. Half of the patients underwent HNRT plus surgery. The other half underwent surgery only and was matched with the treatment patients according to age, sex, and body mass index at a 1:1 ratio. The HRs and BPs in the 2 groups during anesthetic induction, skin incision, and emergence were compared retrospectively. A multivariable model of repeated measures with unstructured covariance structure was used to examine the associations of HNRT with intraoperative HRs and BPs after adjusting for baseline HR and BP, time, use of β-blockers, history of chemotherapy, and American Society of Anesthesiologists physical status score. BPs and HRs were collected every 5 minutes. The baseline HR and BP measurements were not included in the outcome vector and were only used as adjustment for baselines.

RESULTS

Compared with corresponding baseline values in controls, the baseline HR was significantly higher (P = .0012) and the baseline systolic BP was lower (P < .0001) in the treatment group. The baseline diastolic BP levels did not differ significantly (P = .6411). Fewer patients receiving HNRT than controls took β-blockers daily (17% vs 28%; P = .0041). Comparing the corresponding values in control and treatment groups, multivariable analysis revealed significant associations of HNRT with decreases in HR during anesthesia induction (-2.21 [95% confidence interval {CI}, -4.42 to -0.01]; P = .0492) and skin incision (-2.66 [95% CI, -5.16 to -0.16]; P = .0373) and of HNRT with decreases in systolic BP during anesthesia induction (-6.88 [95% CI, -10.99 to -2.78]; P = .0011) and skin incision (-15.87 [95% CI, -20.45 to -11.29]; P < .001). However, we observed a significant association of HNRT with decrease in diastolic BP only during skin incision (-6.50 [95% CI, -9.47 to -3.53]; P < .0001).

CONCLUSIONS

The significant finding in the study was that general anesthesia imposed a negative chronotropic effect on HR in the group given HNRT. Therefore, one should be watchful for bradycardia in these patients; particularly those with low BPs. Their hemodynamics may rapidly progress into an unstable status when bradycardia and hypotension develop altogether.

Baroreceptor reflex failure: Review of the literature and the potential impact on patients with head and neck cancer

BACKGROUND

Baroreceptor dysfunction and reflex failure may occur after surgery affecting the carotid artery. The implications for patients undergoing treatment for head and neck cancer are not well described.

METHODS

A literature search of PubMed was performed between March 2016 and May 2016. Search terms used individually and in combination included: "baroreflex failure," "carotid sinus sensitivity," "carotid endarterectomy," "carotid body tumor," and "head and neck cancer." Bibliographies of included articles were also reviewed for additional pertinent articles.

RESULTS

There is evidence of baroreceptor failure in certain patients after interventions associated with the carotid artery, including carotid endarterectomy and carotid body tumor excision. Few studies have been performed investigating the potential effect of head and neck surgery treatment, including surgery and/or radiation, on baroreflex function.

CONCLUSION

Head and neck cancer treatment has the potential to cause baroreflex failure, and this is likely an underrecognized and underdiagnosed condition.

Evidence of altered autonomic cardiac regulation in breast cancer survivors

PURPOSE

Surgery and adjuvant therapy improved prognosis of breast cancer survivors. This improvement risks being offset by potential late-occurring cardiovascular toxicity of oncologic treatment and increased cardiometabolic risk profile associated with lifestyle changes. We address the hypothesis that in breast cancer survivors, multiple functional alterations might define a phenotype, characterized by vagal impairment, diminished aerobic fitness, increased metabolic risk, and reduced wellbeing.

METHODS

We studied 171 sedentary asymptomatic women (106 cancer survivor-65 controls) of similar age (53 ± 8.6; 51 ± 8.1 years). Autonomic regulation was evaluated by autoregressive spectral analysis of R wave to R wave (RR) interval and systolic arterial pressure variability. Aerobic fitness was directly assessed by cardiopulmonary exercise test. Body mass index (BMI) and waist circumference served as proxies of metabolism. Fatigue and stress-related symptoms were evaluated with validated questionnaire.

RESULTS

Patients showed significantly smaller total RR variance (1644 ± 2363 vs. 2302 ± 1561 msec2), smaller absolute power of low frequency (LF) (386 ± 745 vs. 810 ± 1300 msec2) and high frequency (HF) (485 ± 1202 vs. 582 ± 555 msec2) of RR interval variability and smaller spontaneous baroreflex sensitivity (15.0 ± 8.9 vs. 21.9 ± 10 msec/mmHg), suggesting vagal impairment. VO2 peak and O2 pulse were lower in cancer survivors than in controls. Fatigue and stress-related somatic symptoms scores were higher, as was BMI and waist circumference.

CONCLUSION

Breast cancer survivors show multiple dysfunctions: vagal impairment, lower aerobic fitness, signs of altered metabolism, and higher perception of fatigue.

IMPLICATIONS FOR CANCER SURVIVORS

We propose that the concept of clinical phenotype, which may accommodate multiple functional disturbances, might be useful in long-term personalized prevention programs for breast cancer survivors.

Carotid sinus malfunction presenting with presyncopal episodes during radiation therapy for head and neck cancer

We report the case of a 67-year-old Caucasian man with unexplained presyncopal episodes during radiation therapy for oropharyngeal cancer.

Long-term effects of neck irradiation on cardiovascular autonomic function: a study in nasopharyngeal carcinoma patients after radiotherapy

INTRODUCTION

Baroreflex failure has been reported as a late sequalum of neck radiotherapy. In this study we investigated cardiovascular autonomic function in patients after neck radiotherapy to determine predictive factors associated with outcome.

METHODS

Eighty-nine patients with nasopharyngeal carcinoma were evaluated ≥6 months after radiotherapy for cardiovascular autonomic function and compared with 48 control subjects. Inflammatory markers and carotid intima-media thickness were also assessed.

RESULTS

Autonomic parameters of heart rate response to deep breathing and Valsalva ratio were significantly lower in the patient group. Cardiovascular autonomic impairment was generally mild with relative sparing of the efferent cardiovagal pathway. By univariate and multivariate analyses, the time after radiotherapy and C-reactive protein level were significantly associated with the degree of cardiovascular autonomic dysfunction.

CONCLUSIONS

Radiation-induced cardiovascular autonomic impairment is a dynamic and progressive process that occurs long after radiotherapy. Chronic inflammation plays a major role in this process.

Carotid baroreceptor stimulation for the treatment of resistant hypertension

Interventional activation of the carotid baroreflex has been an appealing idea for the management of resistant hypertension for several decades, yet its clinical application remained elusive and a goal for the future. It is only recently that the profound understanding of the complex anatomy and pathophysiology of the circuit, combined with the accumulation of relevant experimental and clinical data both in animals and in humans, has allowed the development of a more effective and well-promising approach. Indeed, current data support a sustained over a transient reduction of blood pressure through the resetting of baroreceptors, and technical deficits have been minimized with a subsequent recession of adverse events. In addition, clinical outcomes from the application of a new implantable device (Rheos) that induces carotid baroreceptor stimulation point towards a safe and effective blood pressure reduction, but longer experience is needed before its integration in the everyday clinical practice. While accumulating evidence indicates that carotid baroreceptor stimulation exerts its benefits beyond blood pressure reduction, further research is necessary to assess the spectrum of beneficial effects and evaluate potential hazards, before the extraction of secure conclusions.

Does respiratory sinus arrhythmia serve a buffering role for diastolic pressure fluctuations?

Though many consider the magnitude of respiratory sinus arrhythmia as an index of cardiac vagal control, its physiological origins remain unclear. One influential model postulates that the systolic pressure rise within a given beat stimulates the baroreflex arc to adjust the following heart period such that diastolic pressure is "stabilized" and hence displays lesser fluctuation. Accordingly, the magnitude of diastolic pressure fluctuations with respiration should change reciprocally after augmentation or inhibition of respiratory sinus arrhythmia. To test this, we augmented and subsequently inhibited respiratory sinus arrhythmia with vagotonic and vagolytic atropine administration in 19 healthy young volunteers to assess the relation between respiratory R-R interval and diastolic pressure fluctuations. Respiratory diastolic pressure fluctuations showed parallel rather than inverse changes in relation to those in respiratory sinus arrhythmia: they increased with augmented respiratory sinus arrhythmia (138 and 190% of baseline in the frequency and time domains, both P < 0.05) and tended to decrease with inhibited respiratory sinus arrhythmia (82 and 93% of baseline in frequency and time domains, P = 0.20 and P = 0.07). Furthermore, >60% of the change in diastolic pressure fluctuations was explained by the change in respiratory sinus arrhythmia (R(2) = 0.62; P < 0.001), that is, an approximately 50-ms increase or decrease in respiratory sinus arrhythmia resulted in a parallel approximately 1-mmHg change in diastolic pressure fluctuations. Thus, in young healthy individuals during supine rest, respiratory fluctuations in R-R interval do not buffer against diastolic pressure fluctuations but actually cause diastolic pressure fluctuations. Therefore, our data provide little evidence for a predominant role of a baroreflex feedback mechanism underlying respiratory sinus arrhythmia during supine rest.

Carotid baroreceptor stimulation as a therapeutic target in hypertension and other cardiovascular conditions

BACKGROUND

The role of the carotid baroreflex in blood pressure regulation has been known for a long time but its effects were thought to be short lived. Recent data indicate that stimulation of carotid baroreceptors may lower blood pressure not only for short periods of time, but also in the long run.

OBJECTIVE/METHODS

Recent advances in technology permitted the development of a new device (Rheos) that addresses problems with older devices. Several questions remain to be addressed before Rheos can be used widely, and several potential clinical applications remain to be clarified. This review examines these issues and comprehensively describes this therapeutic approach.

RESULTS/CONCLUSIONS

The carotid baroreceptor reflex is probably not completely in control of blood pressure. Baroreflexes are one of many control systems acting in concert.

Postlaryngectomy hypertensive crisis: a manifestation of perioperative acute baroreflex failure?

Hemodynamic instability as a result of altered baroreflex mechanism is common in surgeries involving manipulation around the carotid sheath. We report a case in which hypertensive crisis was associated with laryngectomy during general anesthesia. Perioperative use of vasoactive agents such as alpha(2) agonists may help in maintaining hemodynamic stability in such procedures.

Baroreflex Failure

The baroreflex receives less attention nowadays because most students of hypertension are convinced that faulty volume regulation by the kidneys is responsible for long-term blood pressure increases. However, unusual patients with bilateral destruction of the normal blood pressure-sensing mechanisms can develop profound chronic hypertension. We present 2 patients with baroreflex failure. Both had volatile hypertension with systolic readings up to 300 mm Hg documented over years. Both had muscle sympathetic nerve activity that was increased even while resting. Treating these patients was a stochastic challenge. The therapy is frequently based on medicines that are no longer commonly prescribed.

Denervation of carotid baro- and chemoreceptors in humans

Experimental denervation in animals has shown that carotid baro- and chemoreceptors play an eminent role in maintaining blood pressure and blood gas homeostasis. Denervation of carotid sinus baro- and chemoreceptors in humans may occur as a complication of invasive interventions on the neck or after experimental surgical treatment in asthma. In this topical review, the short- and long-term effects of carotid baro- and chemoreceptor denervation on the control of circulation and ventilation in humans are discussed. Carotid baroreceptor denervation in humans causes a persistent decrease in vagal and sympathetic baroreflex sensitivity and an increase in blood pressure variability; however, carotid denervation does not lead to chronic hypertension. Therefore, although carotid baroreceptors contribute to short-term blood pressure control, other receptors are able to maintain normal chronic blood pressure levels in the absence of carotid baroreceptors. Conversely, carotid chemoreceptor denervation leads to permanent abolition of normocapnic ventilatory responses to hypoxia and reduced ventilatory responses to hypercapnia.