Kunihiro Matsuo

Effects of an Angiotensin II Antagonist on Reperfusion Arrhythmias in Dogs

Losartan, an angiotensin II receptor antagonist with no bradykinin potentiating property, provides the opportunity to study the consequences of blocking angiotensin II. The objective of this study was to evaluate the antiarrhythmic responses of reperfusion arrhythmia to hsartan in dogs. The effects of losartan on ventricular tachyarrhythmias induced during occlusion and reperfusion of the left anterior descending coronary artery were investigated in 30 dogs. The animals were randomized to receive either losartan (n = 15) or saline (n = 15). The VF inducing threshold was measured before occlusion and after reperfusion. Losartan (50 μg/kg per min) or saline was intravenously administered 5 minutes before occlusion and continued throughout the entire study period. The incidence of ventricular tachyarrhythmias during reperfusion was lower in the losartan group than in the control group (4/15 vs 6/15). There was no significant change in VF inducing threshold between the period before occlusion and during reperfusion in the losartan group (10.9 ± 5.7 vs 11.1 ± 5.7mA, P = NS), whereas there was a significant decrease in the control group (15.5 ± 4.4 vs 7.7 ± 3.9 mA, P < 0.01). Blockade of the angiotensin II receptor has beneficial effects on reperfusion arrhythmias.

Effect of intravenous adrenaline before arrival at the hospital in out-of-hospital cardiac arrest

There is some evidence in prospective randomized clinical trials that the administration of adrenaline (AD) before admission for the treatment of out-of-hospital cardiac arrest did not improve survival to hospital discharge. The aim of this study was to evaluate our real-world experience regarding the efficacy of intravenous AD in out-of-hospital cardiac arrest at our university hospital. In this retrospective study, we enrolled and divided 644 patients into AD (AD administration before arrival at the hospital) and non-AD (no AD administration before arrival at the hospital) groups. The patient characteristics including age, sex, percentage of cardiac cause, location of cardiac arrest, and witnessed arrest were similar between the AD and non-AD groups. There were no significant differences between the AD and non-AD groups with regard to return of spontaneous circulation, survival to hospital admission, survival to hospital discharge, or good neurologic recovery at hospital discharge in all patients. In addition, we excluded the data of patients with extrinsic cause. We analyzed whether intravenous AD before arrival in patients with intrinsic cause was effective. The outcomes in the AD group were similar to those in the non-AD group. In conclusion, our study indicated that AD administration before arrival at the hospital for the treatment of out-of-hospital cardiac arrest did not improve the clinical outcome.

Wavelength index: a predictor of the response to disopyramide in paroxysmal lone atrial fibrillation.

We investigated whether the new parameter wavelength index could predict the response to chronic disopyramide therapy in patients with paroxysmal atrial fibrillation (AF). Twenty-seven patients with AF underwent electrophysiologic studies and the wavelength index was determined before and after intravenous administration of disopyramide. Then all patients were treated with oral disopyramide for 6 months. In 17 patients, AF was eliminated (group A), while it persisted in another 10 patients (group B). The ratio of the wavelength index before and after intravenous disopyramide was higher in group A than in group B. Thus, the wavelength index proved useful for predicting the response of AF to disopyramide.

Angiotensin II type 1 receptor blockers do not promote coronary collateral circulation in patients with coronary artery disease.

We previously reported that angiotensin-converting enzyme inhibitors (ACE-Is) promote collateral circulation in patients with coronary artery disease (CAD). There have been many reports on the beneficial effects of angiotensin II type 1 receptor blockers (ARBs) on the cardiac microvasculature. Therefore, the following studies were performed to evaluate the association between treatment with an ARB and the enhancement of coronary collateral circulation as assessed by the Rentrop Score (RS) (Study 1) and to compare these results to those obtained with an ACE-I (Study 2). The subjects were 456 patients with angina who underwent coronary angiography. Study 1: Those who had one (1-V), two (2-V) or three significantly stenosed vessels (3-V) and who received only an ARB without any other anti-hypertensive medication were defined as the ARB group (n=81), and age-, sex- and body mass index–matched subjects (n=146) were selected as a comparative group. There were no significant differences in the percentage of patients with RS≥1 between the two groups. Study 2: Those who received an ACE-I as the only anti-hypertensive treatment were defined as the ACE-I group (n=67), which was matched to the ARB group in Study 1. The percentage of patients with RS≥1 in the ACE-I group was significantly higher than that in the ARB group as assessed by a Cochran-Mantel-Haenszel analysis. In addition, patients with 3-V disease who were treated with an ACE-I, but not an ARB, were most likely (odds ratio [confidence Interval]): 27.7 [4.8–161.0]) to show enhanced collateral circulation, as assessed by a multiple logistic regression analysis. These results suggest that treatment with an ACE-I, but not treatment with an ARB, was associated with the enhancement of collateral circulation in patients with CAD.

Effects of Verapamil on Electrophysiological Properties in Paroxysmal Atrial Fibrillation

Verapamil is used to control ventricular response during atrial fibrillation (AF). Limited data is available on the effects of verapamil on atrial vuinerability in human AF. The effects of intravenous verapamil (0.15 mg/kg) on electrophysiological properties of the atrium were investigated in 12 patients with documented paroxysmal AF by electrophysiological studies. Sinus cycle length, sinus node recovery time, and the effective refractory period of the right atrium were not significantly affected by verapamil. The intraatrial conduction delay zone was significantly increased (33 ± 20 msec before verapamil versus 50 ± 22 msec after verapamil, P < 0.01, and the maximal intraatrial conduction delay was also significantly prolonged by verapamil, both to the His bundle region (30 ±12 msec before verapamil versus 42 ± 15 msec after verapamil. P < 0.01) and to the coronary sinus (40 ± 15 msec before verapamil versus 53 ± 17 msec after verapamil, P < 0.01). The fragmented atrial activity zone was significantly increased (15 ± 14 msec before verapamil versus 25 ± 22 msec after verapamil, P < 0.02), and the percentile fragmented atrial activity was also significantiy increased by verapami] (149 ± 18 msec before verapamil versus 174 ± 44 msec after verapamil, P < 0.05). The repetitive atriaJ firing zone remained unchanged. Sustained AF spontaneousiy occurred in only one patient after the administration of verapamil. Thus, verapamil may modulate the abnormal atrial electrophysiology in paroxysmal AF, and wouid favor production of atrial reentry.

Mechanism of Antiarrhythmic Effects of Class Ic Drugs in Paroxysmal Atrial Fibrillation in Man

While class Ic antiarrhythmic drugs are effective in treating patients with atrial fibrillation, their mechanism of action is poorly understood. We performed electrophysiological studies before and after their administration to 22 patients with paroxysmal atrial fibrillation. Atrial refractoriness, maximal interatrial conduction delay and the wavelength index were measured at two basic cycle lengths (600 or 400 ms). Both drugs studied increased atrial refractoriness and wavelength index. Flecainide reduced the maximal interatrial conduction delay, but pilsicainide did not. Each drug increased the wavelength index in a tachycardia-dependent manner. Class Ic drugs may reduce atrial vulnerability by increasing the wavelength of the reentrant circuit during periods of rapid heart rate.

Intensive LOwering of BlOod pressure and low-density lipoprotein ChOlesterol with statin theraPy (LOBOCOP) may improve neointimal formation after coronary stenting in patients with coronary artery disease.

ObjectiveThis prospective study was carried out to evaluate the benefits of intensive lowering of low-density lipoprotein cholesterol (LDL-C) with statin and intensive blood pressure (BP)-lowering therapy as aggressive medical interventions after stent implantation. MethodsFifty-four patients with coronary artery disease initially received statin immediately after successful stent implantation. They were divided into intensive therapy (IT group, n = 27; therapeutic target levels of LDL-C and BP were 60 mg/dl and <120/80 mmHg at follow-up coronary angiography, respectively, 6–8 months after stent implantation) and conventional therapy groups (CT group, n = 27; target levels of LDL-C and BP were 100 mg/dl and <130/85 mmHg, respectively). Additional antihypertensive therapy with angiotensin II type 1 receptor blockers was begun according to the BP levels. ResultsThere were significant differences in the levels of LDL-C at follow-up between the IT and CT groups [average, 68±10 (cut-off value,≥83.4) mg/dl and 102±14 (<83.4) mg/dl, respectively]. Percentage diameter stenosis (P = 0.039) and diastolic BP (P = 0.005) in the IT group were significantly decreased compared with those in the CT group at follow-up. In addition, percentage diameter stenosis was most significantly related to the level of LDL-C (P = 0.03) among other metabolic factors (BP, body mass index, triglyceride, high-density lipoprotein cholesterol, hemoglobin A1c, and adiponectin) at follow-up as assessed by a stepwise multivariable regression analysis. ConclusionThese results suggest that intensive lowering of LDL-C by statin decreased the neointimal formation after stent implantation, and an LDL-C level of at least 83.4 mg/dl was the most acceptable clinical therapeutic target at follow-up.

Percutaneous cardiopulmonary support for pulmonary thromboembolism caused by large uterine leiomyomata

OBJECTIVE Acute pulmonary thromboembolism (PTE) is a common illness that causes death and disability. Deep vein thrombosis (DVT) is often found in patients with a large myomatous uterus, and can occasionally result in acute PTE. Here, we describe the achievement of a favorable outcome in a case of acute PTE. CASE REPORT The patient presented with acute PTE caused by a large uterine leiomyoma, without DVT of the lower extremities. Percutaneous cardiopulmonary support (PCPS) was used as an adjunct to thrombolytic therapy to treat the right ventricular thrombus with acute PTE. According to emergency practice, PCPS was initiated, and the patient was successfully treated with thrombolytic and anticoagulant therapy associated with total abdominal hysterectomy. CONCLUSIONS This case suggests that PCPS can lead to favorable clinical outcomes in patients with large uterine leiomyomata and severe PTE.

Electrophysiological Properties in Paroxysmal Atrial Fibrillation Complicated with the Wolff-Parkinson-White Syndrome: Comparison with Paroxysmal Atrial Fibrillation Alone

Electrophysiological studies were performed in 26 patients with atrial fibrillation (AF). Thirteen patients had the Wolff-Parkinson-White (WPW) syndrome (group A), and another 13 patients did not have the WPW syndrome (group B). The right atrium effective refractory period was significantly shorter in group A than in group B. The wavelength index which was defined as the ratio of the refractory period to the conduction delay was significantly lower in group A than in group B. Accordingly, patients in group A had a greater tendency to produce atrial reentry than those in group B.

Coarctation of the aorta with some collaterals presenting as aortic dissection detected by 64-MDCT

Coarctation of the aorta with aortic dissection is sometimes seen in cases of Turner syndrome, and most cases are type A aortic dissection, whereas coarctation of the aorta with type B aortic dissection is unusual. Only two cases of coarctation of the aorta presenting as aortic dissection have been reported in Japan, and only a few cases have been reported worldwide. We report here a case of coarctation of the aorta with some collaterals presenting as aortic dissection (type B) detected by 64-multidetector row computed tomography (MDCT). A 36-year-old man was brought to the emergency room complaining of sudden chest pain and back pain. Since he showed highly developed collaterals, he might never have exhibited symptoms or any limits on movement. Three-dimensional image reconstruction enabled detection of the coarctation of the aorta with some collaterals and aortic dissection in the best projection, and enabled assessment of precise anatomical relationship. In the present case, MDCT gave more useful information than cardiac catheterization for planning the surgical repair of coarctation of the aorta with some collaterals presenting as aortic dissection.