Identifying Myocardial Ischemia due to Coronary Microvascular Dysfunction in the Emergency Department: Introducing a New Paradigm in Acute Chest Pain Evaluation

Coronary Microvascular Dysfunction in Asymptomatic Patients with Severe Psoriasis

Severe psoriasis is associated with an increased cardiovascular risk, which may be independent of the traditional risk factors. Coronary microvascular dysfunction (CMD) has been shown to predict a poor cardiovascular prognosis in the general population and in patients with psoriasis. In this study, we assessed the prevalence and predictors of CMD in a large cohort of patients with psoriasis without clinical cardiovascular disease. A total of 503 patients with psoriasis were enrolled and underwent transthoracic Doppler echocardiography to evaluate coronary microcirculation. Of these, 55 patients were excluded from the analyses because of missing data. Of the 448 patients in this study, 31.5% showed CMD. Higher PASI, longer disease duration, the presence of psoriatic arthritis, and hypertension were independently associated with CMD. An increase of 1 point of PASI and 1 year of psoriasis duration were associated with a 5.8% and 4.6% increased risk of CMD, respectively. In our study, CMD was associated with the severity and duration of psoriasis. This supports the role of systemic inflammation in CMD and suggests that the coronary microcirculation may represent an extracutaneous site involved in the immune-mediated injury of psoriasis. We should diagnose and actively search for CMD in patients with severe psoriasis.

Moving from one state to another among patients experiencing unexplained chest pain during physical activity: A secondary qualitative analysis by Meleis transition theory

BACKGROUND

Unexplained chest pain is a common condition in medical settings. Nurses usually coordinate the rehabilitation of patients. Physical activity is recommended; however, it is one of the major avoidance behaviours in patients with coronary heart disease. There is a need for a deeper understanding of the transition that patients with unexplained chest pain undergo during physical activity.

AIM

To develop deeper understanding about experiences of transition in patients with unexplained chest pain during physical activity.

DESIGN

Secondary qualitative analysis of data from three exploratory studies.

METHOD

Meleis et al.'s transition theory was used as a framework for the secondary analysis.

FINDINGS

The transition was complex and multidimensional. The participants experienced personal processes of change toward health within the illness, corresponding to indicators of healthy transitions.

CONCLUSION

The process can be identified as a transition from an uncertain and often sick role to a healthy role. Knowledge regarding transition promotes a person-centred approach in which patients' perspectives are included. Nurses and other health professionals can better direct and plan the caring and rehabilitation of patients with unexplained chest pain by deepening their knowledge of the transition process based on physical activity.

Tipping the scales of understanding: An engineering approach to design and implement whole-body cardiac electrophysiology experimental models

The study of cardiac electrophysiology is built on experimental models that span all scales, from ion channels to whole-body preparations. Novel discoveries made at each scale have contributed to our fundamental understanding of human cardiac electrophysiology, which informs clinicians as they detect, diagnose, and treat complex cardiac pathologies. This expert review describes an engineering approach to developing experimental models that is applicable across scales. The review also outlines how we applied the approach to create a set of multiscale whole-body experimental models of cardiac electrophysiology, models that are driving new insights into the response of the myocardium to acute ischemia. Specifically, we propose that researchers must address three critical requirements to develop an effective experimental model: 1) how the experimental model replicates and maintains human physiological conditions, 2) how the interventions possible with the experimental model capture human pathophysiology, and 3) what signals need to be measured, at which levels of resolution and fidelity, and what are the resulting requirements of the measurement system and the access to the organs of interest. We will discuss these requirements in the context of two examples of whole-body experimental models, a closed chest in situ model of cardiac ischemia and an isolated-heart, torso-tank preparation, both of which we have developed over decades and used to gather valuable insights from hundreds of experiments.

Experiences of unexplained chest pain and physical activity: A Meta-Ethnography

AIMS AND OBJECTIVES

The aim was to examine the experiences of physical activity in the patients with unexplained chest pain.

BACKGROUND

Previous qualitative studies have compiled data on the physical activity experiences of people with unexplained chest pain. Nevertheless, no meta-synthesis exists on this topic to advance the theoretical development of future-related studies.

DESIGN

A meta-ethnographic synthesis of qualitative studies was conducted. Original qualitative studies on the physical activity experiences of people with unexplained chest pain were identified and systematically synthesised using a meta-ethnographic approach.

METHODS

Seven databases were searched for relevant full-text articles in English, Danish, Norwegian and Swedish. There were no limitations concerning year of publication. Articles were first screened against inclusion criteria for eligibility and then assessed for quality and analysed using Noblit and Hare's seven-step meta-ethnography process. The ENTREQ checklist for systematic reviews was used.

RESULTS

Nine qualitative studies were included in the analysis. The physical activity experiences of people with unexplained chest pain illuminates the metaphor: "Physical activity means balancing uncertainty" with four themes: looking for possible explanations, feeling vulnerable, feeling uncertain of consequences and being physically active may mean becoming more capable.

CONCLUSION

For people with unexplained chest pain, being physically active meant moving toward being more capable. The participants felt vulnerable and physical activity helped in balancing uncertainty. A comprehensive model illustrates the antecedents and succedent for the physical activity experiences of individuals with unexplained chest pains.

RELEVANCE TO CLINICAL PRACTICE

An approach to care which considers the patient's experience might be applicable; however, it needs to be accompanied with a biomedical perspective. Nurses and other health professionals need to provide a bridge between the patient's experiences and health professionals' advice and recommendations.

Doppler Echocardiography Assessment of Coronary Microvascular Function in Patients With Angina and No Obstructive Coronary Artery Disease

Echocardiographic evaluation is an essential part of the diagnostic work-up in patients with known or suspected cardiovascular disease. Transthoracic Doppler echocardiography (TTDE) enables straightforward and reliable visualization of flow in the left anterior descending artery. In the absence of obstructive coronary artery disease, low TTDE-derived coronary flow velocity reserve (CFVR) is considered a marker of coronary microvascular dysfunction (CMD). TTDE CFVR is free from ionizing radiation and widely available, utilizing high-frequency transducers, pharmacologic vasodilator stress, and pulsed-wave Doppler quantification of diastolic peak flow velocities. European Society of Cardiology guidelines recommend TTDE CFVR evaluation only following preceding anatomic invasive or non-invasive coronary imaging excluding obstructive CAD. Accordingly, clinical use of TTDE CFVR is limited and CMD frequently goes undiagnosed. An evolving body of evidence underlines that low CFVR is an important and robust predictor of adverse prognosis and continuing symptoms in angina patients both with and without obstructive CAD. The majority of angina patients have no obstructive CAD, particularly among women. This has led to the suggestion that there may be a gender-specific female atherosclerotic phenotype with less epicardial obstruction, and a low CFVR signifying CMD instead. Nevertheless, available evidence indicates low CFVR is an equally important prognostic marker in both men and women. In this review, TTDE CFVR was evaluated regarding indication, practical and technical aspects, and interpretation of results. Association with symptoms and prognosis, comparison with alternative invasive and non-invasive imaging modalities, and possible interventions in angina patients with low CFVR were discussed, and key research questions were proposed.

Brain-heart connections in stress and cardiovascular disease: Implications for the cardiac patient

The influence of psychological stress on the physiology of the cardiovascular system, and on the etiology and outcomes of cardiovascular disease (CVD) has been the object of intense investigation. As a whole, current knowledge points to a "brain-heart axis" that is especially important in individuals with pre-existing CVD. The use of acute psychological stress provocation in the laboratory has been useful to clarify the effects of psychological stress on cardiovascular physiology, immune function, vascular reactivity, myocardial ischemia, neurobiology and cardiovascular outcomes. An emerging paradigm is that dynamic perturbations of physiological and molecular pathways during stress or negative emotions are important in influencing cardiovascular outcomes, and that some patient subgroups, such as women, patients with an early-onset myocardial infarction, and patients with adverse psychosocial exposures, may be at especially high risk for these effects. This review summarizes recent knowledge on mind-body connections in CVD among cardiac patients and highlights important pathways of risk which could become the object of future intervention efforts. As a whole, this research suggests that an integrated study of mind and body is necessary to fully understand the determinants and consequences of CVD.

Coronary Microvascular Dysfunction in Rheumatoid Arthritis Compared to Diabetes Mellitus and Association With All-Cause Mortality

OBJECTIVE

Coronary microvascular dysfunction (CMD) is a predictor of cardiac death in diabetes mellitus (DM) independent of traditional cardiovascular (CV) risk factors. Rheumatoid arthritis (RA) is a chronic inflammatory condition, with excess CV risk compared to the general population, in which CMD is hypothesized to play a role; however, there are limited data on CMD in RA and any association with clinical outcomes. The objective of this study was to compare the prevalence of CMD in RA to that in DM and to test the association with all-cause mortality.

METHODS

We performed a retrospective cohort study using data from a registry of all patients undergoing stress myocardial perfusion positron emission tomography as part of routine clinical care from 2006 to 2017. The inclusion criterion was a normal perfusion scan. Patients with RA or DM were classified using previously published approaches. Coronary flow reserve (CFR) was calculated for all patients in the registry and linked with mortality data. CMD was defined as CFR <2.0.

RESULTS

We studied 73 patients with RA and 441 patients with DM. Among patients with a normal perfusion scan, the prevalence of CMD in RA was similar to that in DM (P = 0.2). CMD was associated with increased risk for all-cause mortality in RA (hazard ratio 2.4 [95% confidence interval 1.4-4.2]) as well as increased risk for cardiac-related death at rates similar to those in DM.

CONCLUSION

These findings suggest an important role for CMD as a potential contributor to excess CV risk and mortality in RA, as previously observed in DM, as well as evidence for a mechanistic link between inflammation and cardiovascular disease.

Association between vertebral bone mineral density, myocardial perfusion, and long-term cardiovascular outcomes: A sex-specific analysis

BACKGROUND

Sexual dimorphism in the manifestation of coronary artery disease (CAD) has unleashed a call to reconsider cardiovascular risk assessment. Alterations of bone mineral density (BMD) have been associated with congestive heart failure and appear to be modified by sex. However, the sex-specific association between BMD, myocardial perfusion, and cardiovascular outcomes is currently unknown.

METHODS

A total number of 491 patients (65.9 ± 10.7 years, 32.4% women) underwent 13N-ammonia positron emission tomography/computed tomography for evaluation of CAD, and were tracked for major adverse cardiac events (MACEs).

RESULTS

Event-free survival (median follow-up time of 4.3 ± 2.0 years) was significantly reduced in patients with low (≤ 100 Hounsfield units) compared to those with higher BMD (log-rank P = .037). Accordingly, reduced BMD was chosen as significant predictor of MACE in a fully adjusted proportional hazards regression model (P = .015). Further, a first-order interaction term consisting of sex and BMD was statistically significant (P = .007). BMD was significantly lower in patients with abnormal myocardial perfusion or impaired left ventricular ejection fraction (P < .05). This difference, however, was noticed in men, but not in women.

CONCLUSIONS

The association between low BMD and cardiovascular disease is sex dependent. Our data suggest that quantification of BMD during myocardial perfusion imaging for evaluation of CAD may be particularly useful in men.

Diagnosis of coronary microvascular dysfunction in the clinic

The coronary microcirculation plays a pivotal role in the regulation of coronary blood flow and cardiac metabolism. It can adapt to acute and chronic pathologic conditions such as coronary thrombosis or long-standing hypertension. Due to the fact that the coronary microcirculation cannot be visualized in human beings in vivo, its assessment remains challenging. Thus, the clinical importance of the coronary microcirculation is still often underestimated or even neglected. Depending on the clinical condition of the respective patient, several non-invasive (e.g. transthoracic Doppler-echocardiography assessing coronary flow velocity reserve, cardiac magnetic resonance imaging, positron emission tomography) and invasive methods (e.g. assessment of coronary flow reserve (CFR) and microvascular resistance (MVR) using adenosine, microvascular coronary spasm with acetylcholine) have been established for the assessment of coronary microvascular function. Individual patient characteristics, but certainly also local availability, methodical expertise and costs will influence which methods are being used for the diagnostic work-up (non-invasive and/or invasive assessment) in a patient with recurrent symptoms and suspected coronary microvascular dysfunction. Recently, the combined invasive assessment of coronary vasoconstrictor as well as vasodilator abnormalities has been titled interventional diagnostic procedure (IDP). It involves intracoronary acetylcholine testing for the detection of coronary spasm as well as CFR and MVR assessment in response to adenosine using a dedicated wire. Currently, the IDP represents the most comprehensive coronary vasomotor assessment. Studies using the IDP to better characterize the endotypes observed will hopefully facilitate development of tailored and effective treatments.

Novel experimental model for studying the spatiotemporal electrical signature of acute myocardial ischemia: a translational platform

Myocardial ischemia is one of the most common cardiovascular pathologies and can indicate many severe and life threatening diseases. Despite these risks, current electrocardiographic detection techniques for ischemia are mediocre at best, with reported sensitivity and specificity ranging from 50%-70% and 70%-90%, respectively.

OBJECTIVE

To improve this performance, we set out to develop an experimental preparation to induce, detect, and analyze bioelectric sources of myocardial ischemia and determine how these sources reflect changes in body-surface potential measurements.

APPROACH

We designed the experimental preparation with three important characteristics: (1) enable comprehensive and simultaneous high-resolution electrical recordings within the myocardial wall, on the heart surface, and on the torso surface; (2) develop techniques to visualize these recorded electrical signals in time and space; and (3) accurately and controllably simulate ischemic stress within the heart by modulating the supply of blood, the demand for perfusion, or a combination of both.

MAIN RESULTS

To achieve these goals we designed comprehensive system that includes (1) custom electrode arrays (2) signal acquisition and multiplexing units, (3) a surgical technique to place electrical recording and myocardial ischemic control equipment, and (4) an image based modeling pipeline to acquire, process, and visualize the results. With this setup, we are uniquely able to capture simultaneously and continuously the electrical signatures of acute myocardial ischemia within the heart, on the heart surface, and on the body surface.

SIGNIFICANCE

This novel experimental preparation enables investigation of the complex and dynamic nature of acute myocardial ischemia that should lead to new, clinically translatable results.

Chronologic and Climatic Factors of Acute Aortic Dissection: Study of 1642 Patients in Two Continents

BACKGROUND

The purpose of this study was to examine whether chronologic and climatic factors and lunar phases affect the onset of acute aortic dissection (AAD).

METHODS

The frequencies of AAD were analyzed with regard to the chronologic and climatic factors and lunar phases on the day when AAD occurred for 1642 patients with AAD from two aortic referral centers in the United States and China.

RESULTS

Mean age of patients was 51.6 ± 13.1 years, and 1260 (76.7%) were men. Dissection was type A in 1125 patients (68.5%) and type B in 517 (31.5%). Early mortality rate was 11.6% (190 of 1642), including 89 aortic ruptures before operation and 101 operative deaths. There was a winter peak in occurrence (33.6%, P < .01) with a relative risk of 1.519. In a week, the frequency was highest on Wednesday (15.5%) and Monday (15.2%), and lowest on Sunday (12.8%). Month-specific incidence was significantly inversely correlated to the mean temperature (rho = -0.650, P = .022) and directly correlated to the atmospheric pressure (rho = 0.706, P = .001). The proportion of type A dissection was significantly higher in the full moon phase compared with type B dissection (73.7% vs 66.9%, P = .012).

CONCLUSIONS

Acute aortic dissection exhibits significant chronologic variation in the frequency of occurrence, with a peak in winter and on Wednesdays, and nadir in summer and on Sundays. The incidence is significantly correlated to the mean temperature and atmospheric pressure. The proportion of type A dissection is higher in the full moon phase. These results are important for understanding the mechanisms involved in triggering AAD events and helpful for improving disease prevention and patient care.

Experimental Validation of Image-Based Modeling of Torso Surface Potentials During Acute Myocardial Ischemia

INTRODUCTION

Myocardial ischemia is an early clinical indicator of several underlying cardiac pathologies, including coronary artery disease, Takatsobu cardiomyopathy, and coronary artery dissection. Significant progress has been made in computing body-surface potentials from cardiac sources by solving the forward problem of electrocardiography. However, the lack of in vivo studies to validate such computations from ischemic sources has limited the translational potential of such models.

METHODS

To resolve this need, we have developed a large-animal experimental model that includes simultaneous recordings within the myocardium, on the epicardial surface, and on the torso surface during episodes of acute, controlled ischemia. Following each experiment, magnetic resonance images were obtained of the anatomy and electrode locations to create a subject-specific model for each animal. From the electrical recordings of the heart, we identified ischemic sources and used the finite element method to solve a static bidomain equation on a geometric model to compute torso surface potentials.

RESULTS

Across 33 individual heartbeats, the forward computed torso potentials showed only moderate agreement in both pattern and amplitude with the measured values on the torso surface. Qualitative analysis showed a more encouraging pattern of elevations and depressions shared by computed and measured torso potentials. Pearson's correlation coefficient, root mean squared error, and absolute error varied significantly by heartbeat (0.1642 ± 0.223, 0.10 ± 0.03mV, and 0.08 ± 0.03mV, respectively).

DISCUSSION

We speculate several sources of error in our computation including noise within torso surface recordings, registration of electrode and anatomical locations, assuming a homogeneous torso conductivities, and imposing a uniform "transition zone" between ischemic and non-ischemic tissues. Further studies will focus on characterizing these sources of error and understanding how they effect the study results.