Coronary microvascular dysfunction (CMD) encompasses several pathogenetic mechanisms involving coronary microcirculation and plays a major role in determining myocardial ischemia in patients with ...angina without obstructive coronary artery disease, as well as in several other conditions, including obstructive coronary artery disease, nonischemic cardiomyopathies, takotsubo syndrome, and heart failure, especially the phenotype associated with preserved ejection fraction. Unfortunately, despite the identified pathophysiological and prognostic role of CMD in several conditions, to date, there is no specific treatment for CMD. Due to the emerging role of CMD as common denominator in different clinical phenotypes, additional research in this area is warranted to provide personalized treatments in this "garden variety" of patients. The purpose of this review is to describe the pathophysiological mechanisms of CMD and its mechanistic and prognostic role across different cardiovascular diseases. We will also discuss diagnostic modalities and the potential therapeutic strategies resulting from recent clinical studies.
Myocardial bridging (MB) is a congenital coronary anomaly in which a segment of the epicardial coronary artery traverses through the myocardium for a portion of its length. The muscle overlying the ...artery is termed a myocardial bridge, and the intramyocardial segment is referred to as a tunneled artery. MB can occur in any coronary artery, although is most commonly seen in the left anterior descending artery. Although traditionally considered benign in nature, increasing attention is being given to specific subsets of MB associated with ischemic symptomatology. The advent of contemporary functional and anatomic imaging modalities, both invasive and noninvasive, have dramatically improved our understanding of dynamic pathophysiology associated with MBs. This review provides a contemporary overview of epidemiology, pathobiology, diagnosis, functional assessment, and management of MBs.
Pathophysiology of Takotsubo Syndrome Pelliccia, Francesco; Kaski, Juan Carlos; Crea, Filippo ...
Circulation,
2017-Jun-13, Volume:
135, Issue:
24
Journal Article
Peer reviewed
Open access
Originally described by Japanese authors in the 1990s, Takotsubo syndrome (TTS) generally presents as an acute myocardial infarction characterized by severe left ventricular dysfunction. TTS, ...however, differs from an acute coronary syndrome because patients have generally a normal coronary angiogram and left ventricular dysfunction, which extends beyond the territory subtended by a single coronary artery and recovers within days or weeks. The prognosis was initially thought to be benign, but subsequent studies have demonstrated that both short-term mortality and long-term mortality are higher than previously recognized. Indeed, mortality reported during the acute phase in hospitalized patients is ≈4% to 5%, a figure comparable to that of ST-segment-elevation myocardial infarction in the era of primary percutaneous coronary interventions. Despite extensive research, the cause and pathogenesis of TTS remain incompletely understood. The aim of the present review is to discuss the pathophysiology of TTS with particular emphasis on the role of the central and autonomic nervous systems. Different emotional or psychological stressors have been identified to precede the onset of TTS. The anatomic structures that mediate the stress response are found in both the central and autonomic nervous systems. Acute stressors induce brain activation, increasing bioavailability of cortisol and catecholamine. Both circulating epinephrine and norepinephrine released from adrenal medullary chromaffin cells and norepinephrine released locally from sympathetic nerve terminals are significantly increased in the acute phase of TTS. This catecholamine surge leads, through multiple mechanisms, that is, direct catecholamine toxicity, adrenoceptor-mediated damage, epicardial and microvascular coronary vasoconstriction and/or spasm, and increased cardiac workload, to myocardial damage, which has a functional counterpart of transient apical left ventricular ballooning. The relative preponderance among postmenopausal women suggests that estrogen deprivation may play a facilitating role, probably mediated by endothelial dysfunction. Despite the substantial improvement in our understanding of the pathophysiology of TTS, a number of knowledge gaps remain.
Circulating levels of microRNA (miR) have been proposed as biomarkers for cardiovascular disease. To identify the heart as a potential source for miRs released into the circulation, we measured ...concentration gradients across the coronary circulation for muscle-enriched (miR-133a, miR-499, miR-208a), vascular (miR-126, miR-92a), leukocyte-related (miR-155), and platelet-enriched (miR-223) miRs.
Circulating miRs were measured by TaqMan polymerase chain reaction in EDTA-plasma simultaneously obtained from the aorta and the coronary venous sinus in patients without coronary artery disease (n=7), with stable coronary artery disease (n=31), and with troponin-positive acute coronary syndromes (n=19). Circulating levels of the muscle-enriched miR-499 (>20-fold; P<0.01), miR-133a (11-fold; P<0.01), and miR-208a (5-fold; P<0.01) were significantly elevated in the aorta of troponin-positive acute coronary syndrome patients compared with patients with coronary artery disease. Importantly, there was a significant increase in circulating levels of miR-499 and miR-133a across the coronary circulation in troponin-positive acute coronary syndrome patients, suggestive of a release into the coronary circulation during myocardial injury. Indeed, miR-499 concentration gradients were significantly correlated with the extent of myocardial damage as measured by high-sensitivity troponin T (r=0.70, P<0.01). In contrast, circulating levels of miR-126 (P=0.16) decreased during transcoronary passage in patients with evidence of myocardial injury, suggesting consumption during transcoronary passage.
Muscle-enriched miR-499 and miR-133a are released from the heart into the coronary circulation on myocardial injury, whereas the vascular miR-126 is consumed during transcoronary passage. The differential regulation of circulating miRs during the transcoronary passage might provide important insights to exploit their role as cardiac biomarkers. Clinical Trial Registration- URL: http://www.germanctr.de. Unique identifier: DRKS00000207; in German Clinical Trials Registry.
To examine differences in myocardial blood flow (MBF) at rest and during stress between patients with type 2 diabetes and control subjects, and to identify potential predictors of changes in MBF at ...rest and during stress.
A cross-sectional study was conducted of 193 patients with type 2 diabetes and 20 age- and sex-matched control subjects. Cardiovascular magnetic resonance was used to evaluate left ventricular structure and function and MBF at rest and during adenosine-induced stress. MBF was derived as the mean of the flow within all segments of a midventricular slice.
Patients with type 2 diabetes had higher global MBF at rest (0.81 ± 0.19 mL/min/g) and lower global MBF during stress (2.4 ± 0.9 mL/min/g) than control subjects (0.61 ± 0.11 at rest, 3.2 ± 0.8 mL/min/g under stress; both
< 0.01). Patients with macroalbuminuria had lower MBF during stress (1.6 ± 0.5 mL/min/g) than did patients with microalbuminuria (2.1 ± 0.7 mL/min/g;
= 0.04), who in turn had lower MBF during stress than did normoalbuminuric patients (2.7 ± 0.9 mL/min/g;
< 0.01). Patients with severe retinopathy had lower MBF during stress (1.8 ± 0.6 mL/min/g) than patients with simplex retinopathy (2.3 ± 0.7 mL/min/g;
< 0.05) and those who did not have retinopathy (2.6 ± 1.0 mL/min/g;
< 0.05). Albuminuria and retinopathy were associated with reduced MBF during stress in a multiple regression analysis. Stress-related MBF inversely correlated with myocardial extracellular volume (
< 0.001;
= 0.37), a measure of diffuse myocardial fibrosis. A trend toward lower basal MBF was observed in patients treated with sodium-glucose cotransporter 2 inhibitors (
= 0.07).
Patients with type 2 diabetes have higher global MBF at rest and lower maximal MBF during vasodilator-induced stress than control subjects. Reduced MBF during stress is associated with diabetes complications (albuminuria and retinopathy) and is inversely correlated with diffuse myocardial fibrosis.
Remote Ischemic Conditioning Heusch, Gerd, MD; Bøtker, Hans Erik, MD, PhD; Przyklenk, Karin, PhD ...
Journal of the American College of Cardiology,
01/2015, Volume:
65, Issue:
2
Journal Article
Peer reviewed
Open access
Abstract In remote ischemic conditioning (RIC), brief, reversible episodes of ischemia with reperfusion in one vascular bed, tissue, or organ confer a global protective phenotype and render remote ...tissues and organs resistant to ischemia/reperfusion injury. The peripheral stimulus can be chemical, mechanical, or electrical and involves activation of peripheral sensory nerves. The signal transfer to the heart or other organs is through neuronal and humoral communications. Protection can be transferred, even across species, with plasma-derived dialysate and involves nitric oxide, stromal derived factor-1α, microribonucleic acid-144, but also other, not yet identified factors. Intracardiac signal transduction involves: adenosine, bradykinin, cytokines, and chemokines, which activate specific receptors; intracellular kinases; and mitochondrial function. RIC by repeated brief inflation/deflation of a blood pressure cuff protects against endothelial dysfunction and myocardial injury in percutaneous coronary interventions, coronary artery bypass grafting, and reperfused acute myocardial infarction. RIC is safe and effective, noninvasive, easily feasible, and inexpensive.
PDF
