BackgroundThe sympathetic nervous system is critical in maintaining the normal physiological function of the heart. Its dysfunction in pathological states may exacerbate the substrate for arrhythmias. Obviously, knowledge of its three-dimensional (3D) structure is important, however, it has been revealed by conventional methods only to a limited extent. In this study, a new method of tissue clearance in combination with immunostaining unravels the 3D structure of the sympathetic cardiac network as well as its changes after myocardial infarction.Methods and resultsHearts isolated from adult male mice were optically cleared using the CUBIC-perfusion protocol. After making the hearts transparent, sympathetic nerves and coronary vessels were immunofluorescently labeled, and then images were acquired. The spatial distribution of sympathetic nerves was visualized not only along the epicardial surface, but also transmurally. They were distributed over the epicardial surface and penetrated into the myocardium to twist around coronary vessels, but also independent from the coronary vasculature. At 2 weeks after myocardial infarction, we were able to quantify both denervation distal from the site of infarction and nerve sprouting (hyperinnervation) at the ischemic border zone of the hearts in a 3D manner. The nerve density at the ischemic border zone was more than doubled in hearts with myocardial infarction compared to intact mice hearts (3D analyses; n = 5, p<0.05).ConclusionsThere is both sympathetic hyperinnervation and denervation after myocardial infarction. Both can be visualized and quantified by a new imaging technique in transparent hearts and thereby become a useful tool in elucidating the role of the sympathetic nervous system in arrhythmias associated with myocardial infarction.

We report a case of Tangier disease with Leriche syndrome and bleeding tendency. In this male patient, nasal hemorrhage had been observed frequently throughout childhood. At 46 years old, he experienced effort angina, and coronary angiography demonstrated 75% stenosis in the right coronary artery. Orange-colored tonsils, mild hepatosplenomegaly and very low levels of serum high-density lipoprotein cholesterol (HDL-C) were observed, and the patient was diagnosed with Tangier disease. At 52 years old, effort angina recurred. Coronary angiography revealed 75% stenosis of the left main trunk, left anterior descending, and right coronary arteries. Stenosis of the brachiocephalic and right common iliac arteries was also recorded. Stents were implanted, and coronary artery bypass surgery was performed. At 53 years old, 15 months after surgery, the patient reported intermittent claudication, coldness of feet, and impotence. Aortic angiography showed progression of the stenosis at the bifurcation of the common iliac artery. The patient was diagnosed with Leriche syndrome, and aorta–left external iliac artery graft bypass surgery was performed. After surgery, oozing from subcutaneous tissue and leaking from the anastomotic region were observed. Additional analysis revealed two single-nucleotide polymorphisms (V825I and N935T) in the ATP-binding cassette transporter A1 (ABCA1) gene, and accumulation of small dense low-density lipoprotein together with low levels of HDL-C. In Tangier disease, HDL-C is markedly decreased because of ABCA1 deficiency. However, this is the first reported case to exhibit extensive atherosclerosis and bleeding tendency. This patient had atypical extensive and multiple atherosclerotic lesions, accompanied by Leriche syndrome and uncontrollable bleeding.

Coronary artery calcium (CAC) is associated with the presence of coronary artery disease (CAD) and cardiovascular risk factors. However, the relation between cardiovascular risk factors and CAD has not yet been fully elucidated in patients with a zero or low coronary artery calcium score (CACS). The purpose of this study was to evaluate the relation of cardiovascular risk factors and angina status to obstructive CAD according to categorical CACS. A total of 753 patients were enrolled in this study. CAC scoring and coronary computed tomographic angiography (CCTA) were performed with dual-source 64-slice CT scanners. The number of patients with a CACS ≤10 and ≤100 were 358 and 528, respectively. Patients with a higher CACS were older and more frequently male, and had a greater frequency of hypertension, diabetes, and hypercholesterolemia. The prevalence of obstructive CAD increased with the CACS. Among patients with a CACS ≤100, age, male gender, diabetes, hypercholesterolemia, and typical angina pectoris were related to obstructive CAD. The presence of hypercholesterolemia was relatively strongly associated with obstructive CAD (OR 6.67, 95% CI 2.91-15.3, p < 0.001) on multivariate analysis. Among patients with a CACS ≤10, men, hypercholesterolemia, and typical angina pectoris were significantly more frequent in patients with than in those without obstructive CAD (p < 0.01). Our data suggest that neither the absence nor low of coronary calcium burden may reliably exclude obstructive CAD in typical symptomatic male patients with hypercholesterolemia. This result may be useful to interpret the relation of CACS to obstructive CAD.

Ectopic foci from pulmonary veins (PVs) comprise the main trigger associated with the initiation of atrial fibrillation (AF). An abrupt anatomical narrow-to-wide transition, modeled as in vitro geometrical patterning with similar configuration in the present study, is located at the junction of PVs and the left atrium (LA). Complex cellular composition, i.e., constituent cell heterogeneity, is also observed in PVs and the PVs-LA junction. High frequency triggers accompanied with anatomical irregularity and constituent cell heterogeneity provoke impaired conduction, a prerequisite for AF genesis. However, few experiments investigating the effects of these factors on electrophysiological properties using human-based cardiomyocytes (CMs) with atrial properties have been reported. The aim of the current study was to estimate whether geometrical patterning and constituent cell heterogeneity under high frequency stimuli undergo conduction disturbance utilizing an in vitro two-dimensional (2D) monolayer preparation consisting of atrial-like CMs derived from human induced pluripotent stem cells (hiPSCs) and atrial fibroblasts (Fbs). We induced hiPSCs into atrial-like CMs using a directed cardiac differentiation protocol with the addition of all- trans retinoic acid (ATRA). The atrial-like hiPSC-derived CMs (hiPSC-CMs) and atrial Fbs were transferred in defined ratios (CMs/Fbs: 100%/0% or 70%/30%) on manually fabricated plates with or without geometrical patterning imitating the PVs-LA junction. High frequency field stimulation emulating repetitive ectopic foci originated in PVs were delivered, and the electrical propagation was assessed by optical mapping. We generated high purity CMs with or without the ATRA application. ATRA-treated hiPSC-CMs exhibited significantly higher atrial-specific properties by immunofluorescence staining, gene expression patterns, and optical action potential parameters than those of ATRA-untreated hiPSC-CMs. Electrical stimuli at a higher frequency preferentially induced impaired electrical conduction on atrial-like hiPSC-CMs monolayer preparations with an abrupt geometrical transition than on those with uniform geometry. Additionally, the application of human atrial Fbs to the geometrically patterned atrial-like hiPSC-CMs tended to further deteriorate the integrity of electrical conduction compared with those using the atrial-like hiPSC-CM alone preparations. Thus, geometrical narrow-to-wide patterning under high frequency stimuli preferentially jeopardized electrical conduction within in vitro atrial-like hiPSC-CM monolayers. Constituent cell heterogeneity represented by atrial Fbs also contributed to the further deterioration of conduction stability.

No abstract