Cell-mediated immunity has been implicated in the pathogenesis of vascular cell injury in patients with athero-sclerotic aortic aneurysms. To clarify the immunologic mechanisms involved, we examined the expression of a cytolytic factor, perforin, in infiltrating cells from aortic tissue samples taken from 6 patients with atherosclerotic aortic aneurysms. Immunohistochemical studies showed that the infiltrating cells consisted mainly of macrophages, natural killer (NK) cells, cytotoxic T lymphocytes (CTLs), and T helper cells, and that perforin was expressed in NK cells and CTLs. Immunoelectron microscopic studies demonstrated that the infiltrating cells released massive amounts of perforin directly on to the surface of arterial vascular cells. These findings provide the first direct evidence that some of the infiltrating cells in the aortic tissue consist of killer cells, and strongly suggest that these killer cells, especially NK cells and CTLs, may play a critical role in the vascular cell injury caused by atherosclerotic aortic aneurysm by releasing perforin. (Jpn Circ J 1997; 61: 965 - 970)

抄録全体を表示

The kinetics of global use-dependent conduction slowing produced by sodium channel blockers in the human heart, estimated as a change in the QRS width, are known to be similar to those of use-dependent block of the maximum rate of depolarization in in vitro studies. However, the kinetics of the regional use-dependent decrease in conductivity have not been investigated. We examined whether the rise time of the monophasic action potential would be clinically useful as a marker of the local use-dependent decrease in conductivity by sodium channel blockers. In 12 patients without organic heart disease, monophasic action potentials (MAPs) were recorded at the right ventricular endocardium using a contact electrode before and after the administration of disopyramide (n=6, 2 mg/kg, iv) or pilsicainide (class Ic agents, n=4, 1 mg/kg, iv, and n=2, 150 mg, po) while the stimulus frequency was abruptly increased from 100/min to 150/min. The rise time, defined as the interval from the pacing pulse to the first peak deflection of the monophasic action potential, and the QRS width were measured simultaneously. In the absence of the sodium channel blockers, the abrupt increase in heart rate did not alter the QRS width or the rise time. In the presence of the agents, both variables were lengthened exponentially. The rate constants of onset changes in the QRS width and the rise time were 2.1±0.5 beats and 2.1±0.4 beats after the administration of disopyramide, and 7.5±3.0 beats and 8.2±4.0 beats after pilsicainide, respectively. The rate constant of the rise time was closely correlated with that of the QRS width. The present results are very closely comparable with the onset rate constants of use-dependent block of the maximum rate of depolarization in in vitro studies. These results suggest that (1) the rise time is a good indicator of local use-dependent decrease in conductivity by sodium channel blockers in human hearts and (2) the local use-dependent decrease in conductivity has kinetics similar to those of use-dependent sodium channel blocks. (Jpn Circ J 1997; 61: 979 - 987)

抄録全体を表示

Although the Maze procedure is highly successful in restoring sinus rhythm in patients with atrial fibrillation (AF), the electrophysiologic changes that occur after the Maze procedure and its mechanism of action are still unclear. The aims of the present study were to examine the electrophysiologic changes that occur in the arrhythmogenic substrate after the Maze procedure and to evaluate the mechanism by which it prevents lone and paroxysmal AF. The modified Maze procedure was performed in 6 patients (6 men, mean age 47±7 years) with lone and paroxysmal AF. Electrophysiologic studies were performed before and 35±8 days after the Maze procedure. Atrial mapping during sinus rhythm revealed that atrial activation propagated smoothly in a concentric circle from the sinus node to other regions in the right atrium and into the coronary sinus before the Maze procedure. Following the Maze procedure, atrial activation propagated selectively through routes produced by incisions or cryoablations in all 6 patients. In addition, double and triple potentials were recorded in regions where conduction blocks were created by the Maze procedure. Neither sinus node function nor AV conduction was changed following the Maze procedure. The Maze procedure did not affect the atrial effective refractory period or the zone of fragmented atrial activity, although the conduction delay zone was increased significantly (p<0.05). AF was inducible in all 6 patients before the Maze procedure, whereas it was not inducible in any patients after the Maze procedure. The Maze procedure is effective in preventing AF without affecting sinus node function and AV conduction. Intra-atrial conduction block produced by incisions or cryoablations contributes to the prevention of AF. (Jpn Circ J 1997; 61: 988 - 996)

抄録全体を表示

We surveyed Japanese experience of coil occlusion of patent ductus arteriosus up to 30 September 1996 by sending questionnaires to 175 hospitals. Thirty-four hospitals reported outcome data for 231 procedures in 218 patients. Successful implantation was achieved in 94% and acute complete closure of the ductus occurred in 71% of those in whom implantation of the coil was successful. Of the latter, 83% reported late complete closure. When those patients who underwent reocclusion for residual shunt are included, 89% attained complete closure. No life-threatening complications have occurred so far. Late reopening was reported in 3 cases. Although the angiographic type of ductus was significantly related to successful implantation (p<0.01), there was no significant correlation with complete occlusion. Ductuses with a minimum diameter greater than 3 mm had a decreased chance of successful implantation, whereas those less than 2 mm had a greater incidence of complete closure. (Jpn Circ J 1997; 61: 997 - 1003)

抄録全体を表示

In order to elucidate the principal cause and actual circumstances of sudden cardiac death in Japan, especially among people in the prime of life, we investigated 133 out of 161 autopsied patients (82.6%) (106 men and 27 women, mean age 47.5 years). Coronary artery disease (CAD) was the most frequently detected disorder (50 cases, 37.6%), and included 15 cases of acute myocardial infarction (AMI) (11.3%). We found that CAD was less frequent among younger patients than in Western countries: 10.0% in subjects in their twenties and 22.2% among subjects in their thirties. The left anterior descending artery (LAD) was the vessel most often affected by infarction (47.0%), but the proportion of LAD lesions was not different from that in AMI patients who were survived for least 1 day after the attack. In conclusion, CAD was infrequent among patients aged 20-39 years in comparison with Western countries and LAD was the most commonly affected vessel, but the proportion was not different from that found among AMI patients who survived for at least 1 day after the attack. (Jpn Circ J 1997; 61: 1004 - 1010)

抄録全体を表示

The use of the internal mammary artery (IMA) in coronary artery bypass surgery has increased substantially over the past 20 years, being at present the conduit of choice for most patients. Complications associated with its use occur occasionally and include life-threatening postoperative ischemia or the revascularized myocardium. We reviewed the records of 1,971 consecutive patients who underwent coronary artery bypass grafting over a 5-year period. All operations included an IMA graft to the left anterior descending coronary artery. Twenty-eight of these patients (1.4%) underwent additional placement of a vein graft on the same region as a salvage maneuver for suspected hypoperfusion as a result of IMA failure. All 28 patients showed life-threatening hemodynamic compromise. Twenty-two of the 28 patients (79%) survived. This was the result of immediate surgical correction, which reversed their hemodynamic instability. IMA hypoperfusion was found more frequently in reoperations and in women and diabetic patients. This syndrome is the result of an imbalance between IMA flow and myocardial demand, causing sudden and unexpected myocardial failure. Its detection and expeditious treatment can successfully modify a serious and potentially lethal clinical situation. (Jpn Circ J 1997; 61: 1011 - 1014)

抄録全体を表示

Although pulmonary venous (PV) flow is closely related to left atrial (LA) pressure dynamics, few investigators have discussed it in relation to LA functions, ie, reservoir, conduit, and booster pump functions. We examined changes in PV flow rate, LA dimension, and left ventricular filling volume in 11 dogs, and assessed the effects of multistaged volume loading on PV flow and LA functions. Systolic PV flow rate (S) increased significantly and reached a plateau, reflecting a limited LA reservoir function. Diastolic PV flow rate (D) increased significantly with an increase in LA pressure. S/D ratio increased non-significantly from 0.87±0.07 before volume loading to 0.96±0.08 until S reached a plateau and then decreased to 0.76±0.08 (p<0.05) because of a significant increase in D without an increase in S at the higher stages of volume loading. During atrial contraction, increases in LA active shortening and left ventricular filling volume were limited, indicating a limited LA forward ejection. The difference between PV flow rate just before and at the end of atrial contraction increased and correlated positively with left ventricular end-diastolic pressure (r=0.57, p<0.01). PV flow varies according to the degree of volume loading and reflects LA functions, which exhibit limited increases in response to volume loading. (Jpn Circ J 1997; 61: 1015 - 1020)

抄録全体を表示

To examine whether amiloride protects against ischemia-induced or reperfusion-induced damage to the heart, mechanical and metabolic studies were performed in the isolated, working rat heart. Ischemia decreased both mechanical function and the tissue levels of high-energy phosphates and increased the tissue levels of free fatty acids (FFAs). Reperfusion restored the levels of high-energy phosphates but further increased FFA accumulation. For this reason, accumulation of FFAs was used as an indicator of both ischemia-induced and reperfusion-induced damage. Drugs were added to the perfusion solution 5 min before ischemia until the end of ischemia (pre) or until 10 min after reperfusion (pre+post). Diltiazem (1 or 5 μmol/L pre) decreased the mechanical function of the non-ischemic heart and attenuated both ischemia-induced and reperfusion-induced accumulation of FFAs. Amiloride (50 μmol/L pre) did not affect the mechanical function of the non-ischemic heart or attenuate ischemia-induced or reperfusion-induced FFA accumulation effectively. However, amiloride (50 μmol/L pre+post) did markedly attenuate the reperfusion-induced accumulation of FFAs. In conclusion, diltiazem attenuates both ischemia-induced and reperfusion-induced myocardial damage, probably through its energy-sparing effect as a result of a decrease in mechanical function before ischemia. In contrast, amiloride attenuates only the reperfusion-induced myocardial damage through mechanisms other than the energy-sparing effect. (Jpn Circ J 1997; 61: 1021 - 1029)

抄録全体を表示

In endothelial cells, bradykinin stimulates the release of intracellular Ca²⁺, which is followed by the entry of extracellular Ca²⁺ into the cells. However, the mechanism underlying this Ca²⁺ entry is not well understood. To investigate the possible implication of tyrosine kinases in bradykinin-mediated Ca²⁺ signaling in endothelial cells, cultured porcine aortic endothelial cells were loaded with fura-2/AM, and Mn²⁺ influx into the cells was determined by the quenching of fluorescence intensity of fura-2 at 360 nm excitation. The tyrosine kinase inhibitors genistein and herbimycin A attenuated not only Ca²⁺ influx but also Mn²⁺ influx from the extracellular space without affecting the release of Ca²⁺ from internal stores in bradykinin-treated cells. In contrast to tyrosine kinase inhibitors, the tyrosine phosphatase inhibitor vanadate stimulated Ca²⁺ influx as well as Mn²⁺ influx. On the other hand, both an inactive analog of genistein, daidzein, and an inhibitor of diacylglycerol (DAG) kinase, ethylene glycol dioctanoate, were without effect on [Ca²⁺]_i following the stimulation of agonist. These findings suggest that tyrosine kinase is involved in the regulation of cation influx in endothelial cells. (Jpn Circ J 1997; 61: 1030 - 1036)

抄録全体を表示

The feasibility of using the heparin-bound percutaneous cardiopulmonary support system (PCPS) for pro-longed extracorporeal circulation in patients with acute severe myocarditis is demonstrated. The case histories of 2 patients with cardiogenic shock caused by acute myocarditis are presented; both were successfully treated with long-term PCPS using a newly developed heparin-binding oxygenator and circuits without changing the oxygenator. The courses of both patients remain uneventful more than 12 months after discharge. We also discuss the clinical aspects of using heparin-bound PCPS in patients with acute severe myocarditis. (Jpn Circ J 1997; 61: 1037 - 1042)

抄録全体を表示

We describe a patient with a right coronary arteriovenous fistula in whom magnetic resonance imaging (MRI) was useful in establishing the diagnosis. In a 36-year-old woman, T1 spin echo MRI demonstrated a massively dilated coronary arteriovenous fistula connecting the right coronary artery to the right atrium. The cine field echo technique showed a continuous shunt flow within the fistula as documented by the flow void throughout the cardiac cycle. These findings were confirmed by cardiac catheterization. We conclude that MRI is useful not only in detecting a coronary arteriovenous fistula but also in identifying its origin and the drainage site. (Jpn Circ J 1997; 61: 1043 - 1046)

抄録全体を表示