Kazuhiro Yajima

Inhibition of endothelium-dependent hyperpolarization by endothelial prostanoids in guinea-pig coronary artery.

In smooth muscle of the circumflex coronary artery of guinea‐pig, acetylcholine (ACh, 10−6 M) produced an endothelium‐dependent hyperpolarization consisting of two components. An initial component that occurs in the presence of ACh and a slow component that developed after ACh had been withdrawn. Each component of the hyperpolarization was accompanied by an increase in membrane conductance. Indomethacin (5×10−6 M) or diclofenac (10−6 M), both inhibitors of cyclooxygenase, abolished only the slow hyperpolarization. The initial hyperpolarization was not inhibited by diclofenac nor by nitroarginine, an inhibitor of nitric oxide synthase. Both components of the ACh‐induced hyperpolarization were abolished in the presence of atropine (10−6 M) or high‐K solution ([K+]0=29.4 mM). The interval between ACh‐stimulation required to generate an initial hyperpolarization of reproducible amplitude was 20 min or greater, but it was reduced to less than 5 min after inhibiting cyclooxygenase activity. Conditioning stimulation of the artery with substance P (10−7 M) also caused a long duration (about 20 min) inhibition of the ACh‐response. The amplitude of the hyperpolarization generated by Y‐26763, a K+‐channel opener, was reproducible within 10 min after withdrawal of ACh. Exogenously applied prostacyclin (PGI2) hyperpolarized the membrane and reduced membrane resistance in concentrations over 2.8×10−9M. At concentrations below threshold for hyperpolarization and when no alteration of membrane resistance occurred, PGI2 inhibited the initial component of the ACh‐induced hyperpolarization. It is concluded that endothelial prostanoids, possibly PGI2, have an inhibitory action on the release of endothelium‐derived hyperpolarizing factor.

Impact of matrix metalloproteinase-2 levels on long-term outcome following pharmacological or electrical cardioversion in patients with atrial fibrillation

AIMS The aim of this study was to evaluate the role of matrix metalloproteinases (MMPs) for the prediction of long-term maintenance of sinus rhythm (SR) after cardioversion in atrial fibrillation (AF). METHODS AND RESULTS The study comprised 102 patients with AF. Pharmacological cardioversion was attempted for a 4-week period with anti-arrhythmic drugs in all patients. Those who failed medication underwent electrical cardioversion. Blood samples for biomarkers and echocardiographic data were obtained at baseline. Thirty-four patients (33.3%) converted to SR by pharmacological (n = 22) and electrical (n = 12) cardioversion and maintained it (SR group). The remaining 68 patients were refractory to the AF (RAF) group including recurrence (n = 22) and unsuccessful treatment (n = 46) after electrical/pharmacological cardioversion. Refractory AF was significantly associated with the duration of AF, hypertension, left atrial diameter, brain natriuretic peptide, MMP-2, and tissue inhibitor of MMP-2. For both multivariable logistic regression analysis and stepwise forward selection procedure, the duration of AF >5 months [odds ratio (OR) 15.32] and MMP-2 >767.0 ng/mL (OR 4.84) were significantly associated with RAF. CONCLUSION Our study suggests that elevated MMP-2 and longer AF duration increased the risk for difficulty in restoring SR in AF patients. Stratification of subjects according to the MMP-2 level may therefore be important for the effective management of AF.

Diagnostic accuracy of cardiac markers for myocardial damage after radiofrequency catheter ablation

AimsThis study compares serum markers of myocardial damage incurred during radiofrequency catheter ablation (RFCA).Methods and resultsBlood was sampled from 34 patients with atrial flutter (n = 16), atrioventricular nodal reentrant tachycardia (AVNRT; n = 13), and Wolff–Parkinson–White syndrome (WPW; n = 5) to measure creatine kinase MB subfraction (CK-MB), human heart-type fatty acid protein (h-FABP), and cardiac troponin T (cTnT) values at baseline and after RFCA. The controls comprised 12 patients without significant elevation of all myocardial markers during electrophysiological study (EPS) without RFCA. h-FABP values did not elevate significantly, whereas CK-MB and cTnT demonstrated significant change after RFCA (P < 0.001). Neither peak h-FABP nor CK-MB correlated with following RFCA parameters: delivery duration, number of RFCA discharges, and cumulative RFCA energy. In contrast, correlations were significant between mean peak values of cTnT and these RFCA parameters (all P < 0.05). The sensitivity (71.6%) and specificity (35.6%) of h-FABP were inferior to those of cTnT (93.3% and 89.8%, respectively).Conclusionh-FABP is an insensitive and less specific marker of myocardial damage in RFCA much along the lines of CK-MB and when compared with the proven accuracy of cTnT.

A rare case of tako-tsubo cardiomyopathy with variable forms of left ventricular dysfunction: A new entity

We report a rare case of an 83-year-old woman with tako-tsubo cardiomyopathy, who presented with variable forms of left ventricular dysfunction during her clinical course. The distribution regional wall-motion abnormalities of the left ventricle on echocardiography had changed from a mid-ventricular ballooning type to the apical ballooning type 3 days from the onset. We suggest that these findings may indicate a new or variant entity of tako-tsubo cardiomyopathy.

Transient mid-ventricular ballooning syndrome complicated by syncope: A variant of tako-tsubo cardiomyopathy

Tako-tsubo cardiomyopathy, also called transient left ventricular apical ballooning, is a clinical entity first described in Japan. This syndrome is triggered by emotional or physical stress and mimics an acute coronary syndrome, although the coronary arteries are essentially normal. Recently, several reports have described variant forms of tako-tsubo cardiomyopathy, such as inverted tako-tsubo and mid-ventricular ballooning cardiomyopathy. We describe a case herein of an 87-year-old woman who presented a variant form of tako-tsubo cardiomyopathy complicated by syncope. Our findings may contribute to an elucidation of the mechanism underlying tako-tsubo cardiomyopathy.

The recurrence of tako-tsubo cardiomyopathy complicated by cardiogenic shock: A case report

Tako-tsubo cardiomyopathy is a stress-related cardiomyopathy which occurs in postmenopausal women after severe emotional stress. Although no evidence supporting specific treatment with tako-tsubo cardiomyopathy has been established, the prognosis is considered favorable with normalization of wall motion abnormalities within weeks. In addition, recurrence of this syndrome seems to be rare. Now, we report a recurrent case of tako-tsubo cardiomyopathy complicated by cardiogenic shock after repeated emotional stress.

Paradoxical brain embolism caused by pulmonary arteriovenous fistula and coincident pulmonary embolism--a case report.

The authors encountered a very rare case of paradoxical brain embolism resulting from pulmonary arteriovenous fistula and coincident pulmonary embolism. Enhanced computed tomography was useful for diagnosing this infrequent condition.

Coronary Artery Spasm during Cryoballoon Ablation in a Patient with Atrial Fibrillation

The patient was a 63-year-old man with drug-resistant atrial fibrillation who developed coronary spasm during cryoballoon ablation (CBA). CBA was started from the left inferior pulmonary vein. ST elevations in II, III, and aVf, with reciprocal ST depressions in V2-5, occurred in association with chest pain just after balloon rewarming and deflation, and the patients blood pressure fell to 50 mmHg. Coronary angiography revealed 90% diffuse stenosis from the orifice of segment 1 to segment 4 in the right coronary artery. The stenosis and ST elevations improved after the intracoronary injection of nitroglycerine. Using continuous peripheral intravenous coronary vasodilation, we electrically isolated the other pulmonary veins with CBA without incident.

A case of floating thrombus in the ascending aorta that caused recurrent peripheral arterial embolic events

We report the case of a 62-year-old man with recurrent arterial embolisms to his arms caused by a thrombosis of the ascending aorta. He had developed a left brachial artery embolism 8 years previously, but presented with a right brachial artery embolus on this occasion. A clot-like mass was seen in the ascending aorta on computed tomography without significant atherosclerosis. Magnetic resonance imaging identified multiple asymptomatic cerebral infarctions. Therefore, we surgically removed the thrombus in the ascending aorta, which was an organized fibrin clot. Pathologically, atherosclerosis and plaque formation were evident at the intima where the clot attached. Clot formation was considered to be due to local arteriosclerosis. We report a case of thrombosis of the ascending aorta causing multiple and recurrent arterial embolisms. The patient had no evidence of coagulation disorders, and arteriosclerotic risk factors such as hypertension, diabetes mellitus, and dyslipidemia were absent. Thus, thrombosis may develop in patients without traditional risk factors. <Learning objective: We report a case of thrombosis of the ascending aorta causing multiple and recurrent arterial embolisms. The patient had no evidence of coagulation disorders, and arteriosclerotic risk factors such as hypertension, diabetes mellitus, and dyslipidemia were absent. Thus, thrombosis may develop in patients without traditional risk factors.>.

Increased Serum Triglyceride Clearance and Elevated High-Density Lipoprotein 2 and 3 Cholesterol During Treatment of Primary Hypertriglyceridemia with Bezafibrate

BACKGROUND Hypertriglyceridemia accompanied by low levels of high-density lipoprotein cholesterol (HDL-C) is a risk factor for coronary artery disease. High-density lipoprotein 2 (HDL2) and 3 (HDL3) are believed to suppress the progress of atherosclerosis through reverse cholesterol transport. As a result, peripheral tissues can be protected against excessive accumulation of cholesterol. Although bezafibrate is known to accelerate the increase of HDL-C, results are not standardized regarding increases of HDL3 and HDL2 subfractions. OBJECTIVE This study assessed the effects of bezafibrate on serum triglyceride (TG) fractional clearance rate (K2) and HDL2 and HDL3 cholesterol (HDL2-C and HDL3-C, respectively) levels in patients with primary hypertriglyceridemia (serum TG ≥150 mg/dL). METHODS Outpatients with primary hypertriglyceridemia were enrolled in this 8-week study conducted at the Third Department of Internal Medicine, Nagoya City University Hospital (Nagoya, Japan). Oral bezafibrate was administered at a dose of 400 mg/d (200-mg tablet BID, morning and evening) for 8 weeks. After 8 weeks, serum levels of total cholesterol (TC), TG, HDL-C, HDL2-C, and HDL3-C were measured. A fat emulsion tolerance test to assess K2 and measurements of plasma lipoprotein lipase (LPL) mass, LPL activity, and hepatic triglyceride lipase (HTGL) activity in postheparin plasma were performed before bezafibrate administration and after the course of treatment. RESULTS Sixteen patients (10 men, 6 women; mean [SD] age, 54 [12] years [range, 30-69 years]; mean [SD] body mass index, 23 [2] kg/m(2)) entered the study. The following findings were observed in male and female patients after 8 weeks of treatment. A statistically significant reduction was observed in mean serum TG level (P<0.01). Significant increases were seen in HDL-C, HDL2-C, and HDL3-C (all P<0.01), K2 (P<0.01), and in plasma LPL mass (P<0.01) and LPL activity (P<0.05). TC level and HTGL activity did not change significantly. No adverse effects related to the use of bezafibrate were documented. CONCLUSIONS In this study, bezafibrate treatment resulted in significant decreases in serum TG level and significant increases in HDL2-C and HDL3-C levels and plasma LPL mass and activity. We hypothesize that bezafibrate may increase HDL3-C by promoting TG-rich lipoprotein catabolism and may increase HDL2-C by promoting the conversion of HDL3 to HDL2.