Atrial flutter with a large bystander segment without double potentials in the cavotricuspid isthmus

We present two cases of common-type atrial flutter with a large bystander segment without double potentials in the cavotricuspid isthmus. In both cases, right atrial angiography demonstrated a prominent pouch at the center of the isthmus. When radiofrequency energy was applied to the tricuspid side of the isthmus, delayed potentials abruptly appeared on the local electrograms. When radiofrequency energy was applied on the inferior vena cava side of the isthmus, the tachycardia was terminated. Although ablation was not applied to the bottom of the pouch, bidirectional isthmus block was achieved. These outcomes indicate that the pouch represented a bystander segment.

Removal of Coronary Sinus Intima by a Guidewire during Cardiac Resynchronization Therapy

Previously, complications associated with the placement of the left ventricular pacing lead were reported in 1.9-6% of cases. We describe a case with a stripping of venous intima from the coronary sinus by a guidewire during a left ventricular lead implantation. Judging from this case, the firm guidewire and coronary catheter should not be used within the coronary sinus.

Inhibition of beta-adrenergic signaling by intracellular AMP is independent of cell-surface adenosine receptors in rat cardiac cells

We report a novel action of intracellular adenosine monophosphate (AMP) to inhibit beta-adrenergic signaling in isolated rat ventricular myocytes. Extracellular application of adenosine or AMP suppressed isoproterenol (Iso)-induced prolongation of action potential duration (APD). This effect was completely abolished by an A(1)-receptor antagonist, DPCPX. Intracellular application of AMP, but not adenosine, attenuated Iso-induced APD prolongation. Iso-induced increases in the L-type Ca(2+) current (I(Ca,L)) were also inhibited by intracellular AMP. These inhibitory effects were not affected by either DPCPX or glibenclamide. In vitro, AMP directly inhibited PKA activity via binding to its regulatory subunit. These results suggest that intracellular AMP attenuates beta-adrenergic signaling by directly inhibiting PKA activity, independently of A(1)-purinergic receptor.

Age-related BM-MNC dysfunction hampers neovascularization

Although ischemia-induced neovascularization is reportedly impaired with aging, the effect of aged-bone marrow mononuclear cells (BM-MNCs) on neovascularization has not been investigated. The neovascularization capacity of BM-MNCs obtained from 8-week-old mice (young) was compared to those obtained from 18-month-old mice (old), both in vivo and in vitro. Neovascularization in ischemic limbs was significantly impaired in old mice. Whereas transplantation of young BM-MNCs significantly improved blood perfusion, tissue capillary density, and vascular endothelial growth factor (VEGF) production in transplanted ischemic limbs, no such effects were observed with old BM-MNCs. Old BM-MNCs also showed a significant impairment of in vitro VEGF production and migratory capacity in response to VEGF. The number of Dil/lectin-positive cells was significantly lower in old mice, but there was no difference in the number of AC133(+)/CD34(+) and CD34(+)/VEGF-R2(+) positive cells between young and old BM-MNCs. Transplantation of young BM-MNCs improved neovascularization and VEGF production in the ischemic limbs of old recipients, with results that were similar to those obtained in young recipients. These results indicate that the neovascularization capacity of transplanted BM-MNCs is impaired with aging. However, aging does not hamper the revitalization of neovascularization in the murine host in response to transplantation of young BM-MNCs.

Radiofrequency catheter ablation for atrial tachycardia originating from the left atrial appendage

A 36-year-old woman presented with drug-refractory atrial tachycardia. During the tachycardia episodes, P waves were positive in leads II, III, aVF, and V1, while they were negative in leads I and aVL. It was hard to determine whether the origin was the left atrial appendage or left superior pulmonary vein on the surface electrocardiogram. Electrophysiologic evaluation revealed that the earliest endocardial activation occurred at the base of the left atrial appendage, preceding the onset of P waves by 38 ms. On initiation of the tachycardia, a warm-up phenomenon was observed. There was a fixed relation between the coupling interval of a single extrastimulus and the return cycle length during the tachycardia. These findings suggested that the mechanism of the tachycardia was automaticity. Application of radiofrequency energy at the left atrial appendage terminated the tachycardia and it was not inducible after ablation.

Remote reperfusion lung injury is associated with AMP deaminase 3 activation and attenuated by inosine monophosphate

BACKGROUND

Remote reperfusion lung injury occurs in patients with vascular occlusion and surgical procedures. Inosine monophosphate (IMP) produced by adenosine monophosphate deaminase (AMPD) 3 is involved in the remote reperfusion injury. The purpose of the present study was to identify whether IMP administration attenuated the remote reperfusion lung injury in a skeletal muscle ischemia-reperfusion model.

METHODS AND RESULTS

A remote reperfusion lung injury was created using reperfusion after the bilateral ligation of the hind-limb. AMPD activity, myeloperoxidase (MPO) activity, IMP, AMPD3 mRNA and tumor necrosis factor (TNF)-alpha in the lungs before and after reperfusion were analyzed. Furthermore, the effects of IMP on these parameters were examined. AMPD3 mRNA, AMPD activity and IMP production in the lungs significantly increased after ischemia-reperfusion with increases in MPO activity, TNF-alpha level and decreased oxygen saturation (SpO(2)). Histological examination of the lungs demonstrated significant neutrophil infiltration and accumulation. IMP administration significantly reduced MPO activity, TNF-alpha and neutrophil infiltration, with ameliorated SpO(2).

CONCLUSIONS

Along with the activation of AMPD3, ischemia-reperfusion-induced lung inflammation is associated with increased MPO activity and TNF-alpha level. IMP significantly decreased the lung injury, MPO activity, TNF-alpha and increased SpO(2). These findings may lead to the development of a new therapeutic strategy for remote reperfusion lung injury.

Plasma levels of uridine correlate with blood pressure and indicators of myogenic purine degradation and insulin resistance in hypertensive patients

BACKGROUND

The relationship between plasma uridine levels and blood pressure (BP), and indicators of muscular purine degradation and insulin resistance (IR) has been evaluated in hypertensive (HT) patients.

METHODS AND RESULTS

In 36 HT patients and 10 normotensive subjects, seated BP was measured, and blood samples were drawn after overnight fast. In 18 of the HT patients, the semi-ischemic forearm test was performed to examine the release of hypoxanthine, ammonium and lactate. Plasma uridine levels were significantly higher than in the normotensive subjects. Fasting plasma insulin levels and homeostasis model assessment of IR correlated with plasma uridine levels in the HT patients. Plasma uridine levels showed a significant correlation with hypoxanthine, ammonia and lactate released from the semi-ischemic exercising muscles of the HT patients.

CONCLUSIONS

Taken together with the positive correlation with indicators of IR, it is suggested that plasma uridine levels in HT are responsible for purine degradation and IR in skeletal muscles.

Catabolism of adenine nucleotides favors adenosine production following exercise in patients with chronic heart failure

BACKGROUND

Adenosine 5'-triphosphate is catabolized to adenosine 5'-monophosphate (AMP), which is further degraded by 2 pathways: deamination to inosine 5'-monophosphate and ammonia by AMP deaminase, or dephosphorylation to adenosine and inorganic phosphate by 5'-nucleotidase. Because adenosine is believed to be cardioprotective and we have reported that ammonia production decreased after exercise in patients with chronic heart failure (CHF), we determined if plasma adenosine levels after exercise increases in patients with CHF.

METHODS AND RESULTS

Maximal ergometer exercise tests with expired gas analysis were performed in 51 patients with CHF (age = 61 +/- 2 years, New York Heart Association [NYHA] class I/II/III = 19/18/14) and 20 age-matched normal controls. Serial changes in both plasma ammonia and adenosine levels were determined. The ratio for delta ammonia to peak work rate became smaller (control, NYHA I/II/III: 0.59 +/- 0.13/0.41 +/- 0.06/0.37 +/- 0.10/0.22 +/- 0.11 microg/dL x watts, respectively) and the ratio for delta adenosine to peak work rate was significantly higher in class III CHF (control, NYHA I/II/III: 0.93 +/- 0.21/0.86 +/- 0.14/1.11 +/- 0.27/2.92 +/- 0.67 nmol/L x watts, respectively).

CONCLUSION

In patients with CHF after exercise, the plasma levels of adenosine increased along with the decrease in the plasma levels of ammonia. Considering the physiologic cardioprotective actions of adenosine, the enhanced adenosine production after exercise may be an important adaptive response in patients with CHF.

Status of Uric Acid Management in Hypertensive Subjects

Hyperuricemia in hypertensive subjects has been considered one of risk factors of cardiovascular diseases. We investigated the status of uric acid management in 799 hypertensive subjects (432 females and 367 males; mean age 70.9 years) managed by 43 doctors (19 cardiologists and 24 noncardiologists; 25 private practice doctors and 18 hospital doctors). The serum uric acid level was available in 85.7% of the patients. This availability was equivalent regardless of facility size, and more cardiologists than noncardiologists monitored this information. The prevalence of hyperuricemia was 17.5% and was higher in men and in patients with high triglyceridemia, left ventricular hypertrophy, renal dysfunction, proteinuria, and smokers, but was not higher in subjects with chronic heart failure, diabetes mellitus, and those with prescriptions for diuretics and beta-blockers. The average serum uric acid level was higher in men and patients with chronic heart failure, renal dysfunction, high triglyceridemia, low high-density cholesterolemia, smokers, and subjects prescribed beta-blockers. Fifty percent of hyperuricemic patients were medicated, and 48.6% of them cleared the uric acid target level (6 mg/dL). No differences were observed in the treatment rate or the achievement rate of the target between genders, concurrent diseases, and physician specialties. Although doctors, especially cardiologists, have a high concern for the serum uric acid level, they do not intervene intensively, and specific treatment for individual patterns is not routinely given. Thus, more attention to uric acid management is necessary in hypertensive subjects to prevent cardiovascular diseases.

Small extra-adrenal pheochromocytoma causing severe hypertension in an elderly patient

We report the case of a 67-year-old woman with severe hypertension caused by an extra-adrenal pheochromocytoma. The tumor was detected by 131I metaiodobenzylguanidine scintigraphy and it was found to be small (2 cm ø) by enhanced CT. After the extirpation of the tumor, the blood pressure of the patient immediately normalized. It should be taken into account that a small extra-adrenal pheochromocytoma can be one of the causes of secondary hypertension in elderly patients. Since small extra-adrenal pheochromocytomas are difficult to detect, it is also important to perform suitable examinations to establish the diagnosis. Furthermore, we emphasize the importance of an accurate diagnosis in elderly patients with pheochromocytoma, for they often have less symptomatology and more severe cardiovascular complications due to refractory hypertension than younger patients.

Delayed onset of beating and decreased expression of T-type Ca2+ channel in mouse ES cell-derived cardiocytes carrying human chromosome 21

The mouse ES cell line hcgp7/#21, which carries a human chromosome 21 (hChr.21), was used as an in vitro model to examine the effects of hChr.21 on cardiomyocyte differentiation. Cardiomyocytes derived from hcgp7/#21 showed a significant delay in the onset of spontaneous beating. The number of Nkx2.5/GFP(+) cardiac progenitor cells was comparable to that in control ES cells and they also expressed comparable mRNA levels for mesodermal markers, cardiac specific transcription factors, contractile proteins, and L-type Ca(2+) channels. However, cells from hcgp7/#21 expressed significantly reduced levels of mRNA for Cav3.1 and Cav3.2, which was consistent with the decreased number of cells expressing T-type Ca(2+) channels and decreased T-type Ca(2+) channel currents. These findings suggest that the presence of human chromosome 21 suppresses expression of T-type Ca(2+) channels in cardiomyocytes during differentiation, which may be responsible for delayed onset of spontaneous beating.

Autoperipheral blood mononuclear cell transplantation improved giant ulcers due to chronic arteriosclerosis obliterans

We report the case of a 74-year-old man with Fontaine stage IV chronic arteriosclerosis obliterans who had been suffering from inveterate giant skin ulcers on the dorsum and heel of the right foot. As conventional medical treatments had not improved these ulcers and surgical treatment was considered unfeasible, amputation of the right lower limb below the knee appeared to represent the only option. The patient was admitted to Tottori University Hospital to attempt a new angiogenic therapy using auto-mononuclear cell transplantation to avoid amputation. On admission, neither right ankle blood pressure nor transcutaneous partial pressure of oxygen at the right toe were detectable. The patient had a history of multiple cerebral infarctions, and collection of mononuclear cells from bone marrow was considered too difficult, so collection of peripheral blood mononuclear cells was selected. Transcutaneous partial pressure of oxygen and skin temperature in the treated limb started to improve from 2 weeks after implantation. Ulcer size was recognizably reduced by 1 month after treatment. Partial auto-skin implantation on the right heel was performed 2 months after treatment, and the giant skin ulcer was finally completely covered. No adverse effects were noted during follow-up lasting 1 year. These results suggest that peripheral blood mononuclear cell implantation may offer a suitable alternative rescue therapy for patients with critical limb ischemia whose general condition is not good.

Ventricular tachycardias and dilated cardiomyopathy caused by Fabry disease

Women with Fabry disease are considered to have a good prognosis. Here we report the clinical history of a female patient with severe Fabry disease before and after referral to our hospital. She was diagnosed to have a cardiac variant of Fabry disease since a left ventricular endomyocardial biopsy revealed specific features of this disease and that cardiac involvement was the sole manifestation. She developed sustained ventricular tachycardia and dilated cardiomyopathy requiring oral administration of amiodarone and a cardiac defibrillator implant.

Allopurinol Reduces Neointimal Hyperplasia in the Carotid Artery Ligation Model in Spontaneously Hypertensive Rats

Uric acid and oxidative stress promote cardiovascular diseases, including atherosclerosis and hypertension. Xanthine oxidase, through which uric acid is generated, is a free-radical generating enzyme. The aim of the current study was to investigate whether allopurinol, an inhibitor of xanthine oxidase activity, affects vascular remodeling and vascular smooth muscle cell (VSMC) proliferation. In the carotid artery ligation model using spontaneously hypertensive rats (SHR), treatment with allopurinol induced a reduction in the neointima/media ratio by 27% (38.5+/-34.3% in the control group and 28.1 20.8% in the allopurinol-treated group, respectively, p<0.01) without alterations in vascular circumference at 3 weeks after ligation when compared to the control. Allopurinol lowered the serum uric acid concentration (147.0+/-3.6 micromol/l in the control group and 16.1+/-3.6 micromol/l in the allopurinol-treated group, respectively p<0.01) and xanthine oxidase activity, but not the blood pressure. In an in vitro study, high concentrations of uric acid (100 and 200 micromol/l) stimulated VSMC growth, but there was no stimulation of these cells by a low concentration of uric acid (50 micromol/I) or by any of three concentrations of xanthine (50, 100 and 200 micromol/l). In addition, allopurinol (5 micromol/I) had no effect on the cell growth. In conclusion, uric acid is a potent stimulator of VSMC proliferation, and allopurinol prevented vascular remodeling in SHR at least in part by inhibiting uric acid concentration.