From heart to brain: the genesis and processing of cardiac pain

Association between Blood Lead Levels and Silent Myocardial Infarction in the General Population

Background: Although the link between lead exposure and patterns of cardiovascular disease (CVD) has been reported, its association with silent myocardial infarction (SMI) remains unexplored. We aimed to assess the association between blood lead levels (BLLs) and SMI risk. Methods: We included 7283 (mean age 56.1 ± 2.52 years, 52.5% women) participants free of CVD from the Third National Health and Nutrition Examination Survey. BLL was measured using graphite-furnace atomic absorption spectrophotometry. SMI was defined as ECG evidence of myocardial infarction (MI) without history of MI. The association between SMI and BLLs was examined using multivariable logistic regression. Results: SMI was detected in 120 participants with an unweighted prevalence of 1.65%. Higher BLL correlated with higher SMI prevalence across BLL tertiles. In multivariable-adjusted models, participants in the third BLL tertile had more than double the odds of SMI (OR: 3.42, 95%CI: 1.76-6.63) compared to the first tertile. Each 1 µg/dL increase in BLL was linked to a 9% increase in SMI risk. This association was consistent across age, sex, and race subgroups. Conclusions: Higher BLLs are associated with higher odds of SMI in the general population. These results underscore the significance of the ongoing efforts to mitigate lead exposure and implement screening strategies for SMI in high-risk populations.

Prevalence, clinical characteristics and associated factors of cardiac cephalalgia: A prospective study

BACKGROUND

The prevalence of cardiac cephalalgia is unknown and there is limited information about its clinical features. We aimed to assess the prevalence of cardiac cephalalgia, its clinical characteristics and associated factors.

METHODS

We conducted a prospective study of patients with suspected acute coronary syndrome admitted to the Cardiology Service at Hospital Clínico Universitario Lozano Blesa, Zaragoza, Spain, over a one-year period. We interviewed patients within the first 24 hours of admission using a standardized case-report form to assess the presence of headache in relation to the acute coronary syndrome and its characteristics.

RESULTS

We included 438 patients, 381 with confirmed myocardial ischemia. Prevalence of cardiac cephalalgia was 14.2% (n = 54). The most common features were frontal location, pressing quality and moderate intensity. Pain referred to the jaws (aOR 2.61; 95% CI 1.33-5.12; p = 0.005), palpitations (aOR 3.65; 95% CI 1.57-8.50; p = 0.003) and circumflex coronary artery as the culprit artery for the myocardial ischemia (aOR 3.8; 95% CI 1.07-13.74; p = 0.021) were related to cardiac whereas history of hypertension was inversely associated (aOR 0.37: 95% CI 0.18-0.74; p = 0.005).

CONCLUSION

The prevalence of cardiac cephalalgia was 14.2%. Our study provides valuable information about cardiac cephalalgia characteristics that suggest revision of current diagnostic criteria.

The Heart as a Target of Vasopressin and Other Cardiovascular Peptides in Health and Cardiovascular Diseases

The automatism of cardiac pacemaker cells, which is tuned, is regulated by the autonomic nervous system (ANS) and multiple endocrine and paracrine factors, including cardiovascular peptides. The cardiovascular peptides (CPs) form a group of essential paracrine factors affecting the function of the heart and vessels. They may also be produced in other organs and penetrate to the heart via systemic circulation. The present review draws attention to the role of vasopressin (AVP) and some other cardiovascular peptides (angiotensins, oxytocin, cytokines) in the regulation of the cardiovascular system in health and cardiovascular diseases, especially in post-infarct heart failure, hypertension and cerebrovascular strokes. Vasopressin is synthesized mostly by the neuroendocrine cells of the hypothalamus. There is also evidence that it may be produced in the heart and lungs. The secretion of AVP and other CPs is markedly influenced by changes in blood volume and pressure, as well as by other disturbances, frequently occurring in cardiovascular diseases (hypoxia, pain, stress, inflammation). Myocardial infarction, hypertension and cardiovascular shock are associated with an increased secretion of AVP and altered responsiveness of the cardiovascular system to its action. The majority of experimental studies show that the administration of vasopressin during ventricular fibrillation and cardiac arrest improves resuscitation, however, the clinical studies do not present consisting results. Vasopressin cooperates with the autonomic nervous system (ANS), angiotensins, oxytocin and cytokines in the regulation of the cardiovascular system and its interaction with these regulators is altered during heart failure and hypertension. It is likely that the differences in interactions of AVP with ANS and other CPs have a significant impact on the responsiveness of the cardiovascular system to vasopressin in specific cardiovascular disorders.

Cardiac cephalalgia: a narrative review and ICHD-3 criteria evaluation

BACKGROUND

Cardiac cephalalgia is an unusual condition that occurs during an episode of myocardial ischemia. Information about cardiac cephalalgia is scarce and its characteristics and physiopathology remain unclear. Our aim is to provide a narrative review of clinical characteristics and physiopathology of cardiac cephalalgia and to evaluate the current diagnostic criteria.  METHODS: A search through PubMed was undertaken for studies on cardiac cephalalgia published until 20th September 2022. We summarized the literature and provide a comprehensive review of the headache characteristics and possible mechanisms. We also evaluated current International Classification of Headache Disorders third edition diagnostic criteria based on prior reported cases.  RESULTS: In total, 88 cases were found. Headache characteristics were variable. Occipital location and throbbing pain were the most frequently reported. Headache was accompanied in most cases by cardiac symptoms. Criterion B was fulfilled by 98% of cases, criterion C1 by 72%, and criteria C2a and C2b by 37 and 93.2%, respectively. Regarding headache features described in diagnostic criterion C3, 'moderate to severe intensity', 'accompanied by nausea', 'not accompanied by photophobia or phonophobia' and 'aggravated by exertion', were reported in 75, 31, 55 and 55% of cases, respectively.

CONCLUSION

Cardiac cephalalgia characteristics are variable and the headache features described in the diagnostic criterion C3 might not be adequate. Given that cardiac cephalalgia can be the manifestation of a life-threatening condition it is important to increase the knowledge about this entity.

The Central Nervous System and Psychosocial Factors in Primary Microvascular Angina

Patients diagnosed with ischemia without obstructive coronary artery disease (INOCA) comprise the group of patients with primary microvascular angina (MVA). The pathophysiology underlying ischemia and angina is multifaceted. Differences in vascular tone, collateralization, environmental and psychosocial factors, pain thresholds, and cardiac innervation seem to contribute to clinical manifestations. There is evidence suggesting potential interactions between the clinical manifestations of MVA and non-cardiac conditions such as abnormal function of the central autonomic network (CAN) in the central nervous system (CNS), pain modulation pathways, and psychological, psychiatric, and social conditions. A few unconventional non-pharmacological and pharmacological techniques targeting these psychosocial conditions and modulating the CNS pathways have been proposed to improve symptoms and quality of life. Most of these unconventional approaches have shown encouraging results. However, these results are overall characterized by low levels of evidence both in observational studies and interventional trials. Awareness of the importance of microvascular dysfunction and MVA is gradually growing in the scientific community. Nonetheless, therapeutic success remains frustratingly low in clinical practice so far. This should promote basic and clinical research in this relevant cardiovascular field investigating, both pharmacological and non-pharmacological interventions. Standardization of definitions, clear pathophysiological-directed inclusion criteria, crossover design, adequate sample size, and mid-term follow-up through multicenter randomized trials are mandatory for future study in this field.

Spinal cord stimulation reduces cardiac pain through microglial deactivation in rats with chronic myocardial ischemia

Angina pectoris is cardiac pain that is a common clinical symptom often resulting from myocardial ischemia. Spinal cord stimulation (SCS) is effective in treating refractory angina pectoris, but its underlying mechanisms have not been fully elucidated. The spinal dorsal horn is the first region of the central nervous system that receives nociceptive information; it is also the target of SCS. In the spinal cord, glial (astrocytes and microglia) activation is involved in the initiation and persistence of chronic pain. Thus, the present study investigated the possible cardiac pain-relieving effects of SCS on spinal dorsal horn glia in chronic myocardial ischemia (CMI). CMI was established by left anterior descending artery ligation surgery, which induced significant spontaneous/ongoing cardiac pain behaviors, as measured using the open field test in rats. SCS effectively improved such behaviors as shown by open field and conditioned place preference tests in CMI model rats. SCS suppressed CMI-induced spinal dorsal horn microglial activation, with downregulation of ionized calcium-binding adaptor protein-1 expression. Moreover, SCS inhibited CMI-induced spinal expression of phosphorylated-p38 MAPK, which was specifically colocalized with the spinal dorsal horn microglia rather than astrocytes and neurons. Furthermore, SCS could depress spinal neuroinflammation by suppressing CMI-induced IL-1β and TNF-α release. Intrathecal administration of minocycline, a microglial inhibitor, alleviated the cardiac pain behaviors in CMI model rats. In addition, the injection of fractalkine (microglia-activating factor) partially reversed the SCS-produced analgesic effects on CMI-induced cardiac pain. These results indicated that the therapeutic mechanism of SCS on CMI may occur partially through the inhibition of spinal microglial p38 MAPK pathway activation. The present study identified a novel mechanism underlying the SCS-produced analgesic effects on chronic cardiac pain.

Gender-stratified analyses of symptoms associated with acute coronary syndrome in telephone triage: a cross-sectional study

OBJECTIVES

To identify clinical variables that are associated with the diagnosis acute coronary syndrome (ACS) in women and men with chest discomfort who contact out-of-hours primary care (OHS-PC) by telephone, and to explore whether there are indications whether these variables differ among women and men.

DESIGN

Cross-sectional study in which we compared patient and call characteristics of triage call recordings between women with and without ACS, and men with and without ACS.

SETTING

Nine OHS-PC in the Netherlands.

PARTICIPANTS

993 women and 802 men who called OHS-PC for acute chest discomfort (pain, pressure, tightness or discomfort) between 2014 and 2016.

PRIMARY OUTCOME MEASURE

Diagnosis of ACS retrieved from the patient's medical record in general practice, including hospital specialists' discharge letters.

RESULTS

Among 1795 patients (mean age 58.8 (SD 19.5) years, 55.3% women), 15.0% of men and 8.6% of women had an ACS. In both sexes, retrosternal chest pain was associated with ACS (women with ACS vs without 62.3% vs 40.3%, p=0.002; men with ACS vs without 52.5% vs 39.7%, p=0.032; gender interaction, p=0.323), as was pressing/heavy/tightening pain (women 78.6% vs 61.5%, p=0.011; men 82.1% vs 57.4%, p=<0.001; gender interaction, p=0.368) and radiation to the arm (women 75.6% vs 45.9%, p<0.001; men 56.0% vs 34.8%, p<0.001; gender interaction, p=0.339). Results indicate that only in women were severe pain (65.4% vs 38.1%, p=0.006; gender interaction p=0.007) and radiation to jaw (50.0% vs 22.9%, p=0.007; gender interaction p=0.015) associated with ACS.Ambulances were dispatched equally in women (72.9%) and men with ACS (70.0%).

CONCLUSION

Our results indicate there were more similarities than differences in symptoms associated with the diagnosis ACS for women and men. Important exceptions were pain severity and radiation of pain in women. Whether these differences have an impact on predicting ACS needs to be further investigated with multivariable analyses.

TRIAL REGISTRATION NUMBER

NTR7331.

Recognizing pain as an early warning symptom of ischemic cardiovascular disease: A qualitative artistic representation of the journey

Background: Understanding the experience of prodromal ischemic cardiac pain and associated symptoms through use of literary and visual art evokes heightened a wareness of the emotional journey.

AIMS

The aim of this study was to describe the initial early prodromal pain-related symptoms and feelings associated with adjusting to this new cardiac health concern and explore the subjective experience of coming to the realization and awareness of developing heart disease.

MATERIALS AND METHODS

This study is a secondary supplemental qualitative analysis, using an arts-based embodied layered exploration assisted to translate the experiences of 23 individuals' journeys through symptom recognition. The analytic process involved three iterative layers: qualitative descriptive analysis of participant pain narratives, interpretation with thematic poetry, and representation via visual art to evoke an aesthetic, heightened level of understanding of the data.

RESULTS

Denial and disbelief, encroaching pain and symptoms of heart disease, and self-recrimination were three themes that emerged from the data. Pain described by participants brought forward the emotional dimensions of the experience. Participants described their process of realization as a tumultuous time, fraught with feelings of vulnerability and uncertainty, where anger and self-effacing ridicule permeated their thoughts that were tempered with profound gratitude at survival.

CONCLUSION

Bridging the connection between science and art to disseminate awareness of the nature of living with cardiac-related prodromal pain and disease is novel. Providing invitation and entrance into an individual's pain experience through qualitative inquiry with use of arts-based approaches makes visible the emotional meaning of pain.

Recurrent asymptomatic Takotsubo syndrome after 20 years: are we looking at the tip of the iceberg only?

Takotsubo syndrome (TS) is an acute and reversible form of myocardial stunning preceded by emotional or physical stress, not explained by an obstruction of an epicardial coronary artery as in acute coronary syndrome. Over the last decades, TS is receiving growing attention, leading to an increase in awareness and diagnostic rate. Chest pain and dyspnea are the most common presenting symptoms; however, nonspecific presentations make the diagnosis challenging for clinicians. Here, we present the case of a 76-year-old female who experienced two completely asymptomatic episodes of TS 20 years apart.

Neural responses during acute mental stress are associated with angina pectoris

Angina pectoris is associated with increased risk of adverse cardiovascular events in coronary artery disease (CAD) patients, an effect not entirely attributable to the severity of CAD.

OBJECTIVE

Examine brain correlates of mental stress in patients with CAD with and without a history of angina.

METHODS

Participants (n = 170) with stable CAD completed the Seattle Angina Questionnaire along with other psychometric assessments. In this cross-sectional study, participants underwent laboratory-based mental stress testing using mental arithmetic and public speaking tasks along with control conditions in conjunction with positron emission tomography brain imaging using radiolabeled water. Brain activity during mental stress was compared between participants who did or did not report chest pain/angina in the previous month. A factor analysis was coupled with dominance analysis to identify brain regions associated with angina.

RESULTS

Participants reporting angina in the past month experienced greater (p < .005) activations within the left: frontal lobe (z = 4.01), temporal gyrus (z = 3.32), parahippocampal gyrus (z = 3.16), precentral gyrus (z = 3.14), right fusiform gyrus (z = 3.07), and bilateral cerebellum (z = 3.50) and deactivations within the right frontal gyrus (z = 3.67), left precuneus (z = 3.19), and left superior temporal gyrus (z = 3.11) during mental stress. A factor containing the left motor areas, inferior frontal lobe, and operculum (average McFadden's number addition = 0.057) in addition to depression severity (0.10) and adulthood trauma exposure (0.064) correlated with angina history.

CONCLUSIONS

Self-reported angina in patients with stable CAD is associated with increased neural responses to stress in a network including the inferior frontal lobe, motor areas, and operculum, potentially indicating an upregulated pain perception response.

Refractory angina is a growing challenge for palliative medicine: a systematic review of non-invasive interventions

BACKGROUND

Refractory angina can have a significant effect on quality of life. Non-invasive interventions have been suggested but there are few guidelines on management. Our aim was to systematically review all studies that reported non-invasive interventions for refractory angina and report on their effectiveness and safety.

METHODS

We performed a literature search of six databases and a grey literature search. Treatments considered first line or second line according to the European Society of Cardiology were excluded, as were interventions that had undergone review within the last 3 years. Design, setting and outcomes were extracted and quality was assessed. A narrative synthesis was undertaken, including an analysis of adverse effects.

RESULTS

4476 studies were screened, 14 studies were included in our analysis. Interventions were specialist multidisciplinary programmes, transcutaneous electrical nerve stimulation (TENS), perhexiline, medical optimisation, morphine and intranasal alfentanil. The effects of specialist programmes and perhexiline treatment were mixed. Positive effects were reported with TENS, opioids and medical optimisation, with improvements in symptoms, exercise capacity and quality of life. No major adverse effects were noted in any of the treatments.

CONCLUSION

There are non-invasive treatments for refractory angina that are overlooked by current guidelines. While the quality of these studies varies, positive changes have been reported in symptoms, exercise tolerance and quality of life with few adverse effects. There is a need for further research into these treatments which could be useful within the contexts of cardiology and palliative care.

Differential role of specific cardiovascular neuropeptides in pain regulation: Relevance to cardiovascular diseases

In many instances, the perception of pain is disproportionate to the strength of the algesic stimulus. Excessive or inadequate pain sensation is frequently observed in cardiovascular diseases, especially in coronary ischemia. The mechanisms responsible for individual differences in the perception of cardiovascular pain are not well recognized. Cardiovascular disorders may provoke pain in multiple ways engaging molecules released locally in the heart due to tissue ischemia, inflammation or cellular stress, and through neurogenic and endocrine mechanisms brought into action by hemodynamic disturbances. Cardiovascular neuropeptides, namely angiotensin II (Ang II), angiotensin-(1-7) [Ang-(1-7)], vasopressin, oxytocin, and orexins belong to this group. Although participation of these peptides in the regulation of circulation and pain has been firmly established, their mutual interaction in the regulation of pain in cardiovascular diseases has not been profoundly analyzed. In the present review we discuss the regulation of the release, and mechanisms of the central and systemic actions of these peptides on the cardiovascular system in the context of their central and peripheral nociceptive (Ang II) and antinociceptive [Ang-(1-7), vasopressin, oxytocin, orexins] properties. We also consider the possibility that they may play a significant role in the modulation of pain in cardiovascular diseases. The rationale for focusing attention on these very compounds was based on the following premises (1) cardiovascular disturbances influence the release of these peptides (2) they regulate vascular tone and cardiac function and can influence the intensity of ischemia - the factor initiating pain signals in the cardiovascular system, (3) they differentially modulate nociception through peripheral and central mechanisms, and their effect strongly depends on specific receptors and site of action. Accordingly, an altered release of these peptides and/or pharmacological blockade of their receptors may have a significant but different impact on individual sensation of pain and comfort of an individual patient.

Cardiac Protective Role of Heat Shock Protein 27 in the Stress Induced by Drugs of Abuse

Heat shock proteins (HSP) are induced after different stress situations. Some of these proteins, particularly HSP-27, function as markers to indicate cellular stress or damage and protect the heart during addictive processes. Morphine withdrawal induces an enhancement of sympathetic activity in parallel with an increased HSP-27 expression and phosphorylation, indicating a severe situation of stress. HSP-27 can interact with different intracellular signaling pathways. Propranolol and SL-327 were able to antagonize the activation of hypothalamic-pituitary adrenal (HPA) axis and the phosphorylation of HSP-27 observed during morphine withdrawal. Therefore, β-adrenergic receptors and the extracellular signal-regulated kinase (ERK) pathway would be involved in HPA axis activity, and consequently, in HSP-27 activation. Finally, selective blockade of corticotrophin releasing factor (CRF)-1 receptor and the genetic deletion of CRF1 receptors antagonize cardiac adaptive changes. These changes are increased noradrenaline (NA) turnover, HPA axis activation and decreased HSP-27 expression and phosphorylation. This suggests a link between the HPA axis and HSP-27. On the other hand, morphine withdrawal increases µ-calpain expression, which in turn degrades cardiac troponin T (cTnT). This fact, together with a co-localization between cTnT and HSP-27, suggests that this chaperone avoids the degradation of cTnT by µ-calpain, correcting the cardiac contractility abnormalities observed during addictive processes. The aim of our research is to review the possible role of HSP-27 in the cardiac changes observed during morphine withdrawal and to understand the mechanisms implicated in its cardiac protective functions.

Effects of osteopathic treatment versus static touch on heart rate and oxygen saturation in premature babies: A randomized controlled trial

BACKGROUND

Osteopathic manipulative treatment (OMT) has been successfully tested in the context of preterm infants. No studies, however, have been conducted to investigate the OMT immediate effects on physiological measurements, such as partial oxygen saturation (SpO2) and heart rate (HR). The purpose of the present study was to assess the effect of osteopathic treatment on SpO2 and HR values and to compare it with 10 min of static touch.

MATERIALS AND METHODS

Ninety-six preterm infants (41 male), aged 33.5 weeks (±4.3) with mean weight at birth of 2067gr (±929) were recruited from the neonatal intensive care unit (NICU) of the Buzzi Hospital in Milan, and randomly allocated to two groups: OMT and Static Touch. Each protocol session consisted of: a) 5-min Pre-touch baseline recording, b) 10-min touch procedure, c) 5-min post-touch recording. Primary and secondary outcomes were, respectively, the baseline changes of HR and SpO2.

RESULTS

The 2 × 2 repeated measure ANOVA for HR showed a statistically significant effect (F (1,94) = 5.34; p < 0.02), revealing that the OMT group decreases the HR value at T2 (p = 0.006). In contrast, SpO2 analysis showed an increase of SpO2 value where the OMT group demonstrated higher values at T2 (p = 0.04).

CONCLUSION

Results from the present study suggest that a single osteopathic intervention may induce beneficial effects on preterm physiological parameters.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT03833635 - Date: February 7, 2019.

The receptive field for visceral pain referred orofacially by the vagus nerves

BACKGROUND

The nociceptive receptive field of the vagus nerves in animals includes virtually the entire thoracic, abdominal and laryngopharyngeal regions. However, the role of the vagus nerves in the transmission of visceral pain in humans, with the exception of pain from coronary artery diseases, is believed to be insignificant.

AIM

The purpose of this report is to map out the clinical visceral pain receptive field of the vagus nerves relative to its nociceptive counterpart in animals.

MATERIALS AND METHODS

The PubMed database and PMC were searched for case reports of patients with orofacial pain believed by the author(s) of the article to be referred from underlying non-cardiac thoracic, laryngopharyngeal or abdominal diseases. Reports of diseases for which non-neural explanations for the orofacial spread of pain were suggested were excluded.

RESULTS

A total of 52 case reports of jaw pain and/or otalgia referred from laryngopharyngeal and noncardiac thoracic sources were discovered. In addition, a multicenter prospective study found that 25.8% of more than 3,000 patients with thoracic aortic dissection experienced pain in the head and neck region. In stark contrast, no case reports of orofacially referred pain from abdominal diseases were found.

DISCUSSION

The results indicate that the laryngopharyngeal and thoracic portions of the vagal receptive field are capable of referring pain orofacially while the abdominal portion is not. The roles of the somatotopic organization of the trigeminal sub nucleus caudalis and neuromodulation in this referral of pain were discussed.

CONCLUSION

Referred orofacial pain can lead to delayed diagnosis and poorer outcome in visceral diseases.

Gender in cardiovascular medicine: chest pain and coronary artery disease

Ischaemic heart disease (IHD) remains the leading cause of morbidity and mortality among women and men yet women are more often underdiagnosed, have a delay in diagnosis, and/or receive suboptimal treatment. An implicit gender-bias with regard to lack of recognition of sex-related differences in presentation of IHD may, in part, explain these differences in women compared with men. Indeed, existing knowledge demonstrates that angina does not commonly relate to obstructive coronary artery disease (CAD). Emerging knowledge supports an inclusive approach to chest pain symptoms in women, as well as a more thoughtful consideration of percutaneous coronary intervention for angina in stable obstructive CAD, to avoid chasing our tails. Emerging knowledge regarding the cardiac autonomic nervous system and visceral pain pathways in patients with and without obstructive CAD offers explanatory mechanisms for angina. Interdisciplinary investigation approaches that involve cardiologists, biobehavioural specialists, and anaesthesia/pain specialists to improve angina treatment should be pursued.

Emergency Department Clinician Experiences and Perceptions Regarding Noncardiac Chest Pain: A Cross-Sectional Survey

OBJECTIVES

The objectives of this study are to report the responses of emergency department (ED) clinicians regarding the characteristics and management of patients with noncardiac chest pain (NCCP) and to explore clinician experiences with the current standard of care and whether nonpharmacologic or nonsurgical referral options would be considered.

METHODS

A cross-sectional survey was delivered to 40 ED clinicians from hospitals in Winnipeg, Manitoba from 2012 to 2013. Data were reduced descriptively and thematically summarized to assess the characteristics of patients with NCCP along with the responses of ED clinicians regarding the management of NCCP.

RESULTS

The survey response was 27 (67.5% response rate). They reported that patients with NCCP comprised a considerable amount of ED care and are a variable and heterogeneous population. Respondents agreed (63.0%) that onsite and on-call providers for NCCP referral would assist in patient management. Further, ED clinicians (66.7%) would consider referring patients with NCCP to a nonpharmacologic, nonsurgical clinical research study.

CONCLUSION

Clinicians in this study wanted better access to on-site referrals and outpatient clinics for patients experiencing NCCP after discharge and would consider nonpharmacologic or nonsurgical referral.

Chronic myocardial infarction changed the excitatory-inhibitory synaptic balance in the medial prefrontal cortex of rat

The medial prefrontal cortex is a key area for the regulation of pain and emotion. However, the functional involvement of the medial prefrontal cortex for visceral nociception, at the neuronal or synaptic level, is obscure yet. In the present study, the properties of excitatory and inhibitory synaptic transmission within the layer II/III of rat medial prefrontal cortex after chronic myocardial infarction were studied. It is found that the excitation–inhibition ratio of the medial prefrontal cortex was greatly changed, with enhanced excitation and decreased inhibition inputs to the pyramidal cells of the medial prefrontal cortex, which largely due to decreased spike firing in gamma-aminobutyric acid-ergic neurons. Behaviorally, inhibition of gamma-aminobutyric acid-ergic synaptic transmission alleviated the visceral pain and anxiety. It is thus for the first time showing that the excitation–inhibition ratio is increased in the medial prefrontal cortex after chronic myocardial infarction, which may come from the reduced intrinsic activity of gamma-aminobutyric acid-ergic neurons and is important for regulating the angina pectoris and anxiety induced by chronic myocardial infarction.

Chest pain as a manifestation of hypokalemia in a pediatric patient

Patients presenting to the emergency department with chest pain are common and a cause of significant concern to patients and families and physicians alike. The causes of chest pain are myriad. These causes span diverse categories including cardiovascular, respiratory, abdominal and gastrointestinal, musculoskeletal, psychiatric, hematologic and oncologic, and neurologic Thull-Freedman (2010) [1]. These diverse etiologies present a diagnostic and management challenge to the ER physician who is tasked to minimize unnecessary diagnostics while not missing any significant disease. Multiple reviews have discussed the various etiologies of chest pain in the pediatric patient presenting to the ER but none of these recent reviews has included hypokalemia as a cause of chest pain Talner and Carboni (2000), Cava and Sayger (2004), Ringstrom and Freedman (2006), Foy and Filippone (2015), Yeh and Yeh (2015) [2-6]. Additionally, no reviews of hypokalemia describe this condition presenting with chest pain (Mandal, 1997; Gennari, 2002; Medford-Davis and Rafique, 2014 [7-9]). This case report describes a pediatric patient who presents with chest pain that was attributed to hypokalemia. This report attempts to make practitioners aware that hypokalemia may present with chest pain and to encourage ER providers to include this in the differential diagnosis.

Anatomy and physiology of phrenic afferent neurons

Large-diameter myelinated phrenic afferents discharge in phase with diaphragm contraction, and smaller diameter fibers discharge across the respiratory cycle. In this article, we review the phrenic afferent literature and highlight areas in need of further study. We conclude that 1) activation of both myelinated and nonmyelinated phrenic sensory afferents can influence respiratory motor output on a breath-by-breath basis; 2) the relative impact of phrenic afferents substantially increases with diaphragm work and fatigue; 3) activation of phrenic afferents has a powerful impact on sympathetic motor outflow, and 4) phrenic afferents contribute to diaphragm somatosensation and the conscious perception of breathing. Much remains to be learned regarding the spinal and supraspinal distribution and synaptic contacts of myelinated and nonmyelinated phrenic afferents. Similarly, very little is known regarding the potential role of phrenic afferent neurons in triggering or modulating expression of respiratory neuroplasticity.

The effects of endothelin-1 on satellite glial cells in peripheral ganglia

Endothelins (ET) are a family of highly active neuropeptides with manifold influences via ET receptors (ETR) in both the peripheral and central nervous systems. We have shown previously that satellite glial cells (SGCs) in mouse trigeminal ganglia (TG) are extremely sensitive to ET-1 in evoking [Ca²⁺]_in increase, apparently via ET_BR activation, but there is no functional information on ETR in SGCs of other peripheral ganglia. Here we tested the effects of ET-1 on SGCs in nodose ganglia (NG), which is sensory, and superior cervical ganglia (Sup-CG), which is part of the sympathetic nervous system, and further investigated the influence of ET-1 on SGCs in TG. Using calcium imaging we found that SGCs in intact, freshly isolated NG and Sup-CG are highly sensitive to ET-1, with threshold concentration at 0.1nM. Our results showed that [Ca²⁺]_in elevation in response to ET-1 was partially due to Ca²⁺ influx from the extracellular space and partially to Ca²⁺ release from intracellular stores. Using receptor selective ETR agonists and antagonists, we found that the responses were mediated by mixed ET_AR/ET_BR in SGCs of NG and predominantly by ET_BR in SGCs of Sup-CG. By employing intracellular dye injection we examined coupling among SGCs around different neurons in the presence of 5nM ET-1 and observed coupling inhibition in all the three ganglion types. In summary, our work showed that SGCs in mouse sensory and sympathetic ganglia are highly sensitive to ET-1 and that this peptide markedly reduces SGCs coupling. We conclude that ET-1, which may participate in neuron-glia communications, has similar functions in wide range of peripheral ganglia.

T4 syndrome - A distinct theoretical concept or elusive clinical entity? A case report

T4 syndrome has existed as a clinical concept for more than three decades and it has been identified as a source of upper extremity (UE) symptoms. This case report explores the clinical reasoning in the diagnoses and management of a patient with symptoms consistent with T4-type syndrome and critically discusses the concept of T4 syndrome using recent research to help explain the clinical presentation. Manual therapy treatment focused on stimulation of the sympathetic ganglia, decreasing local upper thoracic pain and UE referral pattern noted during passive examination. The successful outcomes included immediate and lasting symptom relief after upper thoracic spinal manipulation. Although treatment has been based on the theory that mechanical thoracic dysfunction can produce sympathetic nervous system (SNS) referred pain, the role the sympathetic reflexes potentially plays on the referral symptoms to the UE presently remains unclear.

Pain and Anxiety in Rural Acute Coronary Syndrome Patients Awaiting Diagnostic Cardiac Catheterization

CONTEXT

In rural areas of Canada, people with acute coronary syndromes (ACS) can wait up to 32 hours for transfer for diagnostic cardiac catheterization (CATH). While awaiting CATH, it is critical that pain and anxiety management be optimal to preserve myocardial muscle and minimize the risk of further deterioration.

OBJECTIVES

The aim of this study was to examine the relationship between clinical management, cardiac pain intensity, and state anxiety for rural ACS patients awaiting diagnostic CATH.

METHODS

In a prospective, descriptive-correlational repeated-measures design involving 121 ACS rural patients, we examined the associations of analgesic and nitroglycerin administration with cardiac pain intensity (numeric rating scale) and state anxiety (Spielberger State Anxiety Inventory) and also nurses' pain knowledge and attitudes (Toronto Pain Management Inventory-ACS Version and Knowledge and Attitudes Survey Regarding Pain) using linear mixed models.

RESULTS

The mean age of patients was 67.6 ± 13, 50% were men, and 60% had unstable angina and the remainder had non-ST-elevated myocardial infarction. During follow-up, cardiac pain intensity scores remained in the mild range from 1.1 ± 2.2 to 2.4 ± 2.7. State anxiety ranged from 44.0 ± 7.2 to 46.2 ± 6.6. Cumulative analgesic dose was associated with a reduction in cardiac pain by 1.0 points (numeric rating scale, 0-10) (t108 = -2.5; SE, -0.25; confidence interval, -0.45 to -0.06; P = .013). Analgesic administration was not associated with state anxiety. Over the course of follow-up, ACS patients reported consistently high anxiety scores.

CONCLUSIONS

Whereas cardiac pain declines in most patients in the early hours after admission, many patients experience a persistent anxious state up to 8 hours later, which suggest that development and testing of protocols for anxiety reduction may be needed. More urgently, the development and examination of a treatment intervention, early on in the ACS trajectory, are warranted that targets pain and anxiety for those for whom immediate angioplasty is not possible and who continue to experience cardiac pain and persistent high levels of anxiety. Moreover, a larger prognostic study is required to determine whether high levels of anxiety in rural ACS patients are predictive of major adverse cardiac events.

Management of Refractory Angina Pectoris

With improvements in survival from coronary artery disease (CAD) and an ageing population, refractory angina (RA) is becoming an increasingly common clinical problem facing clinicians in routine clinical practice. These patients experience chronic symptoms in the context of CAD, characterised by angina-type pain, which is uncontrolled despite optimal pharmacological, interventional and surgical therapy. Although mortality rates are no worse in this cohort, patients experience a significantly impaired quality of life with disproportionately high utilisation of healthcare services. It has been increasingly recognised that the needs of RA patients are multifactorial and best provided by specialist multi-disciplinary units. In this review, we consider the variety of therapies available to clinicians in the management of RA and discuss the promise of novel treatments.

Role of satellite glial cells in gastrointestinal pain

Gastrointestinal (GI) pain is a common clinical problem, for which effective therapy is quite limited. Sensations from the GI tract, including pain, are mediated largely by neurons in the dorsal root ganglia (DRG), and to a smaller extent by vagal afferents emerging from neurons in the nodose/jugular ganglia. Neurons in rodent DRG become hyperexcitable in models of GI pain (e.g., gastric or colonic inflammation), and can serve as a source for chronic pain. Glial cells are another element in the pain signaling pathways, and there is evidence that spinal glial cells (microglia and astrocytes) undergo activation (gliosis) in various pain models and contribute to pain. Recently it was found that satellite glial cells (SGCs), the main type of glial cells in sensory ganglia, might also contribute to chronic pain in rodent models. Most of that work focused on somatic pain, but in several studies GI pain was also investigated, and these are discussed in the present review. We have shown that colonic inflammation induced by dinitrobenzene sulfonic acid (DNBS) in mice leads to the activation of SGCs in DRG and increases gap junction-mediated coupling among these cells. This coupling appears to contribute to the hyperexcitability of DRG neurons that innervate the colon. Blocking gap junctions (GJ) in vitro reduced neuronal hyperexcitability induced by inflammation, suggesting that glial GJ participate in SGC-neuron interactions. Moreover, blocking GJ by carbenoxolone and other agents reduces pain behavior. Similar changes in SGCs were also found in the mouse nodose ganglia (NG), which provide sensory innervation to most of the GI tract. Following systemic inflammation, SGCs in these ganglia were activated, and displayed augmented coupling and greater sensitivity to the pain mediator ATP. The contribution of these changes to visceral pain remains to be determined. These results indicate that although visceral pain is unique, it shares basic mechanisms with somatic pain, suggesting that therapeutic approaches to both pain types may be similar. Future research in this field should include additional types of GI injury and also other types of visceral pain.

Personality subtypes and chest pain in patients with nonobstructive coronary artery disease from the TweeSteden Mild Stenosis study: mediating effect of anxiety and depression

BACKGROUND

Patients presenting with chest pain in nonobstructive coronary artery disease (CAD, luminal narrowing <60%) are at risk for emotional distress and future events. We aimed to examine the association of personality subtypes with persistent chest pain, and investigated the potential mediating effects of negative mood states.

METHODS

Any chest pain in the past month was the primary outcome measure reported by 523 patients with nonobstructive CAD (mean age 61.4 years, SD = 9.4; 48% men), who participate in the TweeSteden Mild Stenosis (TWIST) observational cohort. Personality was categorized into a 'reference group', a high social inhibition ('SI only'), a high negative affectivity ('NA only') and a 'Type D' (NA and SI) group. Negative mood states included symptoms of depression and anxiety (Hospital Anxiety and Depression Scale) and cognitive and somatic depression (Beck Depression Inventory). The PROCESS macro was used to examine the relation between personality subtypes and chest pain presence, with the negative mood states as potential mediators.

RESULTS

Persistent chest pain was present in 44% of the patients with nonobstructive CAD. Type D personality (OR = 1.91, 95% CI 1.24-2.95), but not the 'NA only' (OR = 1.48, 95% CI 0.89-2.44) or the 'SI only' (OR = 0.93, 95% CI 0.53-1.64) group was associated with chest pain, adjusted for age and sex. Negative mood states mediated the association between personality and chest pain.

CONCLUSIONS

Type D personality, but not negative affectivity or social inhibition, was related to chest pain in nonobstructive CAD, which was mediated by negative mood states.

The excitatory synaptic transmission of the nucleus of solitary tract was potentiated by chronic myocardial infarction in rats

Angina pectoris is a common clinical symptom that often results from myocardial infarction. One typical characteristic of angina pectoris is that the pain does not match the severity of the myocardial ischemia. One possible explanation is that the intensity of cardiac nociceptive information could be dynamically regulated by certain brain areas. As an important nucleus for processing cardiac nociception, the nucleus of the solitary tract (NTS) has been studied to some extent. However, until now, the morphological and functional involvement of the NTS in chronic myocardial infarction (CMI) has remained unknown. In the present study, by exploring left anterior descending coronary artery ligation surgery, we found that the number of synaptophysin-immunoreactive puncta and Fos-immunoreactive neurons in the rat NTS two weeks after ligation surgery increased significantly. Excitatory pre- and postsynaptic transmission was potentiated. A bath application of a Ca²⁺ channel inhibitor GABApentin and Ca²⁺ permeable AMPA receptor antagonist NASPM could reverse the potentiated pre- and postsynaptic transmission, respectively. Meanwhile, rats with CMI showed significantly increased visceral pain behaviors. Microinjection of GABApentin or NASPM into the NTS decreased the CMI-induced visceral pain behaviors. In sum, our results suggest that the NTS is an important area for the process of cardiac afference in chronic myocardial infarction condition.

Sympathetic ganglion transcutaneous electrical nerve stimulation after coronary artery bypass graft surgery improves femoral blood flow and exercise tolerance

We tested the hypothesis that transcutaneous electrical nerve stimulation (TENS) over the stellate ganglion region would reduce sympathetic overstimulation and improve femoral blood flow (FBF) after coronary artery bypass graft surgery. Thirty-eight patients (20 men, 24 New York Heart Association class III-IV) were randomized to 5-day postoperative TENS (n = 20; 4 times/day; 30 min/session) or sham TENS (n = 18) applied to the posterior cervical region (C7-T4). Sympathetic nervous system was stimulated by the cold pressor test, with FBF being measured by ultrasound Doppler. Femoral vascular conductance (FVC) was calculated as FBF/mean arterial pressure (MAP). Six-min walking distance established patients' functional capacity. Before and after the intervention periods, pain scores, opiate requirements, and circulating β-endorphin levels were determined. As expected, preoperative MAP increased and FBF and FVC decreased during the cold pressor test. Sham TENS had no significant effect on these variables (P > 0.05). In contrast, MAP decreased in the TENS group (125 ± 12 vs. 112 ± 10 mmHg). This finding, in association with a consistent increase in FBF (95 ± 5 vs. 145 ± 14 ml/min), led to significant improvements in FVC (P < 0.01). Moreover, 6-min walking distance improved only with TENS (postsurgery-presurgery = 35 ± 12 vs. 6 ± 10 m; P < 0.01). TENS was associated with lesser postoperative pain and opiate requirements but greater circulating β-endorphin levels (P < 0.05). In conclusion, stellate ganglion TENS after coronary artery bypass graft surgery positively impacted on limb blood flow during a sympathetic stimulation maneuver, a beneficial effect associated with improved clinical and functional outcomes.

Mechanism of dorsal column stimulation to treat neuropathic but not nociceptive pain: analysis with a computational model

OBJECTIVE

Stimulation of axons within the dorsal columns of the human spinal cord has become a widely used therapy to treat refractory neuropathic pain. The mechanisms have yet to be fully elucidated and may even be contrary to standard "gate control theory." Our hypothesis is that a computational model provides a plausible description of the mechanism by which dorsal column stimulation (DCS) inhibits wide dynamic range (WDR) cell output in a neuropathic model but not in a nociceptive pain model.

MATERIALS AND METHODS

We created a computational model of the human spinal cord involving approximately 360,000 individual neurons and dendritic processing of some 60 million synapses--the most elaborate dynamic computational model of the human spinal cord to date. Neuropathic and nociceptive "pain" signals were created by activating topographically isolated regions of excitatory interneurons and high-threshold nociceptive fiber inputs, driving analogous regions of WDR neurons. Dorsal column fiber activity was then added at clinically relevant levels (e.g., Aβ firing rate between 0 and 110 Hz by using a 210-μsec pulse width, 50-150 Hz frequency, at 1-3 V amplitude).

RESULTS

Analysis of the nociceptive pain, neuropathic pain, and modulated circuits shows that, in contradiction to gate control theory, 1) nociceptive and neuropathic pain signaling must be distinct, and 2) DCS neuromodulation predominantly affects the neuropathic signal only, inhibiting centrally sensitized pathological neuron groups and ultimately the WDR pain transmission cells.

CONCLUSION

We offer a different set of necessary premises than gate control theory to explain neuropathic pain inhibition and the relative lack of nociceptive pain inhibition by using retrograde DCS. Hypotheses regarding not only the pain relief mechanisms of DCS were made but also regarding the circuitry of pain itself, both nociceptive and neuropathic. These hypotheses and further use of the model may lead to novel stimulation paradigms.

Acute Coronary Syndrome Pain and Anxiety in a Rural Emergency Department: Patient and Nurse Perspectives

Rural patients can wait up to 32 hours for transfer to cardiac catheterization (CATH) for events related to acute coronary syndrome (ACS). Pain arising from myocardial ischemia can be severe and anxiety-provoking. Pain management during this time should be optimized in order to preserve vulnerable myocardial muscle. This qualitative focus group study solicited the perspectives of ACS patients and emergency staff nurses on the rural patient experience of cardiac pain and anxiety and priorities and barriers to optimal assessment and management of ACS pain. Patients described ACS pain as moderate to severe, with pain in the chest, arms, back, shoulders, and jaw. Pain was well assessed and managed upon arrival in the emergency department but anxiety was not routinely assessed or treated. Barriers identified were poor management of patients with different acuity levels, high patient volumes, and assumptions regarding patients' communication about pain. Research related to ACS pain and anxiety management in the rural context is recommended.

Different brain activation under left and right ventricular stimulation: an fMRI study in anesthetized rats

BACKGROUND

Myocardial ischemia in the anterior wall of the left ventricule (LV) and in the inferior wall and/or right ventricle (RV) shows different manifestations that can be explained by the different innervations of cardiac afferent nerves. However, it remains unclear whether information from different areas of the heart, such as the LV and RV, are differently processed in the brain. In this study, we investigated the brain regions that process information from the LV or RV using cardiac electrical stimulation and functional magnetic resonance imaging (fMRI) in anesthetized rats because the combination of these two approaches cannot be used in humans.

METHODOLOGY/PRINCIPAL FINDINGS

An electrical stimulation catheter was inserted into the LV or RV (n = 12 each). Brain fMRI scans were recorded during LV or RV stimulation (9 Hz and 0.3 ms width) over 10 blocks consisting of alternating periods of 2 mA for 30 sec followed by 0.2 mA for 60 sec. The validity of fMRI signals was confirmed by first and second-level analyses and temporal profiles. Increases in fMRI signals were observed in the anterior cingulate cortex and the right somatosensory cortex under LV stimulation. In contrast, RV stimulation activated the right somatosensory cortex, which was identified more anteriorly compared with LV stimulation but did not activate the anterior cingulate cortex.

CONCLUSION/SIGNIFICANCE

This study provides the first evidence for differences in brain activation under LV and RV stimulation. These different brain processes may be associated with different clinical manifestations between anterior wall and inferoposterior wall and/or RV myocardial ischemia.

Women, cardiac syndrome X, and microvascular heart disease

New data suggest that persistent chest pain, despite normal coronary angiography, is less benign than previously thought. It has long been recognized that cardiac syndrome X (CSX) is associated with significant suffering, disability, and health care costs, but the biggest shift in thinking comes in terms of long-term risk. It is now recognized that the prognosis is not benign and that a significant proportion of patients are at increased cardiovascular disease risk. Of major debate is the question of whether the mechanisms that explain this chest pain are cardiac vs noncardiac. The most current definition of CSX is the triad of angina, ischemia, and normal coronary arteries, which is associated with an increased cardiovascular risk. This paper provides a review of CSX, epidemiology of the problem, proposed explanatory mechanisms, and important next steps in research. Central to this review is the proposition that new insights into CSX will be fostered by both clinical and scientific collaboration between cardiovascular and pain scientists.