A study on determinants of the inducibility and maintenance of atrial fibrillation / 대한내과학회지

BACKGROUND: Atrial fibrillation (AF) is thought to beget AF by shortening atrial refractoriness and reversal of rate adaptation of atrial refractoriness. This phenomenon of electrophysiologic remodeling of the atria during AF has been reported to play a major role in inducibility and stability of AF. METHODS: Thirty-one patients with induced AF lasting >1 second during electrophysiologic study for documented or suspected supraventricular or ventricular tachycardia were included in this study. All the patients had no structural heart disease and history of AF. High right atrium (HRA) burst pacing or extra-stimulation was applied to induce AF. Eleven patients with AF sustained >or=3 min was grouped into Group I and 20 patients with AF <3 min into Group II. P wave duration and amplitude, left atrial (LA) size, atrial refractory period (ARP), intraatrial conduction time (IACT) from HRA electrode catheter to His bundle electrode catheter and characteristics of atrial activities during induced AF were compared between 2 groups. RESULTS: There was no difference in the distribution of underlying cardiac arrhythmias. P wave durations and amplitudes and echocardiographic LA sizes were similar between 2 groups. ARPs and IACTs in group I and II were similar (198.0 +/- 23.9 ms vs. 200.8 +/- 23.0 ms; 38.7 +/- 8.5 ms vs. 38.6 +/- 9.5 ms, respectively). During AF, mean interval of atrial activities in group I was significantly shorter than group II (156.6 +/- 24.2 ms vs. 187.6 +/- 28.0 ms, p<0.01). The degree of irregularity of atrial activities during AF was significantly higher in group I than group II (16.9 +/- 8.7 vs. 9.8 +/- 5.0, p<0.05). The duration of the atrial activities was wider in group I than group II (81.4 +/- 17.5 ms vs. 53.9 +/- 12.4 ms, p<0.001) and the amplitude was lower in group I than group II (56.1 +/- 36.0% vs. 109.0 +/- 51.8%, p<0.05), and the degree of fractionation was greater in group I than group II (4.8 +/- 1.1 vs. 3.2 +/- 0.5, p<0.05). CONCLUSION: These results suggest that shortening of atrial refractoriness and lengthening of local conduction time at the time of or shortly after induction of AF may play a major role in the induction and stabilization of AF.

The Effects of Anti-Platelet Agents in Preventing Coronary Stent Restenosis

BACKGROUND: Restenosis is still remained as the most important limitation in clinical practice with coronary stent. Experimental study in a porcine model and clinical study in patients with coronary artery disease were performed to test the efficacy and safety of various anti-platelet agents (Aspirin, Ticlopidine, Cilostazol) to prevent restenosis of coronary stent. METHODS: In animal study, Cilostazol 200 mg/day (Group I, n=7) or Ticlopidine 500 mg/day (Group II, n=4) in addition to Aspirin (300 mg/day) was administered to pigs from 3 days before stenting to 4 weeks after stenting. Angiographic and pathologic findings were compared at 4 weeks after stenting. In clinical study, 134 patients underwent coronary stent as Group A (46 patients with 49 lesions:39 M, 7 F:60.8+/-10.1 year) receiving 300 mg Aspirin and 200 mg Cilostazol, and Group B (88 patients with 92 lesions:63 M, 25 F:60.6+/-8.8 year) receiving 300 mg Aspirin and 500 mg Ticlopidine between Sep '97 and May '98 at Chonnam University Hospital. RESULTS: Angiographic degree of stenosis at baseline, immediately after and at 4 weeks after stent was not different between Group I and II. With the histopathologic examination of the stented artery segments 4 weeks after stenting, diameter stenosis was 44.8+/-25.5% in Group I and 64.2+/-6.7% in Group II, which was not different (p=0.054). In clinical study, clinical diagnosis and indications for stent were not different between two Groups. Acute stent thrombosis developed in one (1.1%) of Group B and subacute stent thrombosis in three (6.5%) of Group A. Restenosis of the stented coronary artery was observed in 3 (18.8%) in Group A and 10 (37.0%) in Group B (p=NS). Minimal luminal diameter was 2.17+/-1.49 mm in Group A and 2.05+/-1.15 mm in Group B (p=NS). No patient in Group A developed side effect, while 4 (4.5%) patients developed side effects including toxic hepatitis in one, gastritis in one patient and thrombocytopenia in two patients. CONCLUSION: Combination antiplatelet therapy with Cilostazol and Aspirin is equally effective and more safe in the prevention of coronary stent restenosis, compared with the conventional therapy using Ticlopidine and Aspirin.

Successful Coronary Interventions with the Aid of Abciximab (ReoPro (R)) in High-Risk Patients: Report of Two Cases / 대한구급학회지

Abrupt closure of coronary artery during coronary intervention is one of major limitations especially in high-risk patients. Platelets are responsible for composing acute thrombotic occlusion at the site of therapeutic arterial injury. Abciximab (platelet glycoprotein IIb/IIIa receptor blocker) might be helpful in preventing the acute thrombotic occlusion. We experienced an excellent effects of the drug in two cases of high-risk patients, unsuccessful thrombolytics and PTCA with acute occlusion. With additional use of abciximab we overcame the complications and succeeded in getting normal coronary flow and resultant successful angioplasties.

Alterations in Myocardial Perfusion and Regional Wall Motion in Patients with Permanent Pacemaker

BACKGROUND: The effect of right ventricular pacing on myocardial perfusion and regional wall motion is not well known, although some studies have suggested that it may be adverse. We investigated the effects of right ventricular pacing on myocardial perfusion and regional wall motion in patients with permanent pacemakers. METHOD: Thirty patients receiving permanent pacemakers for complete heart block or sick sinus syndrome were included in this study. All the patients showed normal coronary angiograms. Myocardial scintigraphy and two-dimensional echocardiography were performed to assess myocardial perfusion and to evaluate regional wall motion and global function of the left ventricle (LV). RESULTS: 1) Mean age was 66.2+/-8.2 (41-84) years, and the male-to-female ratio was 1 : 1.7 (11 male, 19 female). Indications for permanent pacemaker implantation were complete atrioventricular (AV) block in 21 patients and sick sinus syndrome in 9. The selected pacing modes were VVI in 14 patients, DDD in 8, VDD in 6, and AAI in 2. LV ejection fraction estimated by 2-dimensional echocardiography was 62.7+/-5.8 (53-86)%. 2) Perfusion defects were noted in 26 (87%) patients including 25 (89%) out of 28 patients with ventricular pacing modes such as VVI, DDD, and VDD, and 1 (50%) out of 2 patients with AAI mode. Locations of perfusion defects were septal in 19 (63%) patients, inferior in 17 (57%), apical in 16 (53%), lateral in 3 (10%), and anterior in 2 (7%). Extent of maximal perfusion defects was 17.0+/-9.5 (0-44)%. 3) Regional wall motion abnormalities were noted mainly over the apical region of the LV in 26 (93%) of 28 patients with ventricular pacing. However, LV ejection fraction did not differ significantly before and early after implantation of the pacemaker (62.7+/-5.8% vs. 61.0+/-5.8%, p-0.313). CONCLUSIONS: Right ventricular apical pacing frequently caused myocardial perfusion defects and regional wall motion abnormalities. These might be due to abnormal ventricular activation and abnormal interventricular septal motion. The long-term effects of these abnormalities remain to be determined, and the pacing technique to minimize these adverse effects should be developed.

The Effects of Oral Nitric Oxide Donor (Molsidomine) in Patients with Variant Angina Unresponsive to Conventional Anti-Anginal Drugs

BACKGROUND: We observed the changes of clinical characteristics after oral Molsidomine, a nitric oxide donor, in patients who have documented coronary artery spasm by ergonovine coronary angiogram and refractory to conventional anti-anginal therapy. METHOD: Molsidomine, oral nitric oxide donor, was administrated over 12 weeks in 20 patients (6 male, 14 female, 54+/-11.5 years) in order to observe the clinical effects in patients with coronary artery spasm unresponsive to nitrate and calcium channel blockers. Changes in the frequency of pain and sublingual nitroglycerin use, blood pressure, heart rate, side effects, electrocardiogram, and laboratory findings were evaluated before and after Molsidomine therapy. RESULTS: The frequencies of pain and sublingual nitroglycerin use were 3.9+/-0.9/week before treatment and decreased to 2.9+/-0.9/week at 4th week after the additional Molsidomine treatment (pre-treatment vs. 4th week; p<0.001), to 1.0+/-0.8/week at 8th week (4th week vs. 8th week; p<0.001), and to 0.7+/-0.8/week at 12th week. Systolic blood pressure decreased after treatment, but there were no significant changes in diastolic blood pressure, heart rate, resting electrocardiogram and laboratory findings. Molsidomine was discontinued in one patient because of headache. CONCLUSIONS: Molsidomine is an effective and well tolerated anti-ischemic agent in patients with variant angina refractory to conventional anti-anginal therapy.

Clinical Characteristics of Korea Women with Ischemic Heart Disease

BACKGROUND: The prevalence of ischemic heart diseases (IHD) has increased remarkably during the past 10 years in Korea. Because only few reports on risk factors of IHD in Korean women exist, the aim of this study was to determine the clinical characteristics (including risk factors) of IHD in Korean women. METHODS: Fifty-six female patients and 122 (out of 655) of male patients with significant coronary artery stenosis were included in this study. There were 12 cases of angina pectoris and 35 cases of myocardial infarction in the 56 female patients. There were 54 cases of angina pectoris and 68 cases of myocardial infarction in the 122 male patients. Age and sexdistributions, risk factors of atherosclerosis, and coronary angiographic findings were compared between the female and male patients. RESULTS: The female patients were older than the male patients (63+/-8 years vs. 58+/-4 years, p or = 2) was greater in men than in women (43% vs. 25%, p<0.05). Hypertension was more prevalent (66% vs. 11%, p<0.001) and smoking was less (65% vs. 11%, p<0.001) in women than men. After age adjustment, hypertension was more frequent in women, and smoking was more in men (p=0.001). On coronary angiograms there were no difference in the morphology of coronary artery stenosis, the distribution of culprit vessels, and the number of vessels involved between women and men, In terms of therapeutic modalities, there were no differences between women and men in our study. CONCLUSIONS: In Koean women with IHD, hypertension is more common and smoking is less common. However, coronary artery lesion morphology and distribution are comparable between women and men.

Comparison of Porcine Corinary Stent Restenosis between MAC (Maximum Arterial Re-Creation)and Palmaz-Schatz Stent

BACKGROUND: Coronary stents are effective in the treatment of acute complications after angioplasty and the prevention of restenosis. However, complications may arise posttreatment, the major cinical problems are stent thrombosis and restenosis. All coronary stents are imported from western countries and are not covered by medical insurance in Korea. Korean stents should be developed to reduce patient's economic burden. METHODS: We placed five Maximum Arterial Re-Creation (MAC) and five Palmaz-Schatz (PS) stents in ten porcine coronary arteries. Stent and artery diameter ratio was 1.3 : 1.0. Follow-up coronary angiogram and histopathologic examinations were performed four weeks after stent overdilation injury. RESULTS: All of the stented arteries were patent on follow-up coronary angiograms. Angiographic diameter stenosis was 23.1+/-9.2% in MAC stents and 18.5+/-12.3% in PS stents and pathologic area stenosis was 35.6+/-11.4% in MAC stent and 39.8+/-9.9% in PS stent at 4 weeks after stenting, which were not different between two stents. Maximal intimal thickness (0.28+/-0.12 vs. 0.36+/-0.17mm) and neointimal area (1.83+/-1.01mm2 vs. 1.50+/-0.65mm2) were not different between MAC and PS stent. CONCLUSIONS: MAC stents are as effective as PS stents in the prevention of stent restenosis in a porcine stent restenosis model.

The Early Results of Clinical and Angiographic Follow-up after Coronary Interventions for Restenotic Lesions

BACKGROUND: Coronary intervention is a well established treatment of ischemic heart diseases. However, acute arterial occlusion and restenosis have remained as the principal limitations of coronary intervention. This study was aimed to analyze the acute and long-term, and the clinical angiographic results of the coronary intervention for restenotic lesions. METHOD: Between March 1996 and July 1997 at Chonnam University Hospital, second interventions were performed in one hundred restenotic coronary lesions of ninety patients (age 58.5+/-9.0 year, M:F = 5:1), i.e. percutaneous transluminal coronary angioplasty (PTCA) or stent implantation for the treatment of restenosis. RESULTS: 1) Initial interventions were PTCA in 75 lesions (Group I) and stent in 25 lesions (Group II). There were no differences in clinical manifestations, angiographic findings and follow-up period between the two groups. 2) The method of the second intervention for the restenotic lesions after PTCA were either PTCA or stent implantation ; in Group I PTCA was performed in 27 (37%) lesions and stent in 46 (63%), In Group II, PTCA was performed in 20 (91%) lesions and stent in 2 (9%) lesions. The overall success rate of the second intervention for the restenotic lesion was 96%. 3) Follow-up angiogram at 5.5+/-2.9 months after the second intervention revealed the second restenosis rates of 44% (8/18) after stent and 50% (7/14) after PTCA. CONCLUSION: Second intervention for restenotic lesion can be performed with high success rate. Second restenosis rate are not different between the PTCA and stent groups.

Clinical Characteristics of Coronary Interventions in Old Aged Patients

BACKGROUND: Coronary intervention is one of well established therapeutic modalities for patients with ischemic heart diseases. With the prolonged life expectancy and changes in dietary habits in Korea, the number and percentage of elderly patients with ischemic heart disease have increased in interventional coronary therapies. METHOD: There were 1762 patients (age> or = 70 years : 253, age<70 years: 1509) who underwent diagnostic coronary angiogram at Chonnam University Hospital between Jan '96 and Jun '97. We compared clinical characteristics, coronary lesion morphology, success rates and complications of coronary interventions in control and aged groups. RESULTS: 1) Female patients were more prevalent in aged group (43 %; 145 male, 108 female) than in the control group (35%; 982 male, 527 female, p<0.05). 2) The diagnostic sensitivity of coronary angiogram was higher in the aged (169/253, 67 %) than in control group (738/1509, 49 %, p<0.05). Multivessel diseases were more prevalent in the aged (65 %) than in the control groups (49%). 3) Coronary interventions were performed less frequently in the aged group (119/169, 70 %) than in the control group (605/738, 82%, p<0.05). The success rates of PTCA were not different between in the aged (89%) and control (93%) groups, and the success rates in stenting was also not different between the aged (98%) and control (99%) groups. 4) Procedure-related complications (4.6 vs. 7.6 %) and mortalities (0.5 vs 0.8 %) during and after coronary interventions were not different in control and elderly groups. CONCLUSION: Coronary interventions in patients older than 70 years can be performed with high success and low complication rates ; the results do not differ from those of younger patients.

Two Cases of Sliding Hiatal and Morgagni Hernia Mimicking Pericardial Lipomas

The differential diagnosis between pericardial and non-cardiac masses may be sometimes difficult in the evaluation of chest mass adjacent to the heart. One misdiagnosed case of non-cardiac mass as a pericardial mass turned out to be a hernia. When the contents of hernia originate from the gastrointestinal tract, the diagnosis is made easily by air-fluid shadow on plain chest roentgenogram. Morgagni hernia is usually detected on plain chest roentgenograms as a smooth, supradiaphragmatic shadow at the right pericardiophrenic angle. In the case of Morgagni hernia, in which the contents are only the omentum, it is necessary to differentiate the hernia from mediastinal fatty tumors. We report two cases of hiatal and Morgagni hernia containing omentum which were misdiagnosed as pericardial masses.

Predictors for In-stent Restenosis after Coronary Microstent II Implantation

BACKGROUND: Coronary stent is known as an effective treatment in the intimal dissection after angioplasty and the prevention of restenosis. However, in-stent restenosis still remains a major concern in clinical stenting. METHOD: The Microstents were placed in 151 patients from May '96 to Aug '97 and performed follow-up coronary angiograms in 49 (32.5%) patients. To identify the clinical, angiographic and procedure-related variables that predict late restenosis within the stented artery, 49 patients (58+/-8 year:38 M, 11 F) were studied. Indications for stenting were 25 de novo (52.8%), 9 restenotic (18.7%), 8 suboptimal PTCA (16.7%) and 6 bail-out lesions (12.6%). All patients were treated with aspirin and ticlopidine for one month after stenting. The follow-up angiograms were obtained at 5+/-3 months and variables of 13 patients with restenosis were compared with those of 36 patients without restenosis. RESULTS: The in-stent restenosis rate was 26.5%. Univariate logistic regression analysis was used to determine how in-stent restenosis was influenced. Clinical diagnosis, presence of risk factors, lipid profiles, numbers of involved vessels, target arteries, lesion length, lesion types, stent length, maximal inflation pressure, predilation balloon size, reference vascular diameter, minimal luminal diameter, and stent to artery diameter ratio were analyzed. Among these variables, only lesion length before stent implantation was a predictor for in-stent restenosis (19.9+/-11.1 mm vs. 10.9+/-7.3 mm, p=.017). CONCLUSION: Lesion length before Microstent II implantation is the single predictor of late in-stent restenosis.

Clinical Experiences of Coronary MAC (Maximum Arterial Re-Creation) Stent

BACKGROUND AND OBJECTIVES: We previously reported the effects of MAC (Maximum Arterial Re-Creation) stent on stent restenosis in a porcine model. The clinical trial was performed in patients with ischemic heart disease after MAC stent implantation. MATERIALS AND METHOD: We analyzed the clinical and angiographic results in 20 patients in 22 lesions (15 M, 5 F, 59+/-11 year), who underwent MAC stent at Chonnam University Hospital between Nov '97 and Aug '98. Clinical diagnosis was 13 unstable angina (65%), 6 acute myocardial infarction (30%) and 1 old myocardial infarction (5%). RESULTS: Indications for stent were 3 de novo lesion (13.6%), 7 restenosis (31.8%), 8 suboptimal angioplasty result (36.4%) and 4 bail-out procedure (18.2%). Target stented coronary arteries were 15 left anterior descending coronary arteries (67.3%), 2 left circumflex coronary arteries (9.1%) and 5 right coronary arteries (22.7%). Morphologic types were 13 type B1 (59.1%), 5 B2 (22.7%) and 4 C (18.2%). Minimal luminal diameter (MLD) before stent was 0.75+/-0.35 mm and percent diameter stenosis (DS) was 75+/-11.5%, which were improved 2.97+/-0.28 mm in MLD and 2.79+/-5.4% in DS after stent. MAC stent was placed successfully in all patients and one case of acute stent thrombosis was improved after ReoPro infusion. Mean follow-up period was 5.2+/-3.2 months and 100 % event-free survival was observed in all patients. Follow-up coronary angiography was performed in 5 patients and showed no stent restenosis. CONCLUSION: The MAC stent is one of effective and safe devices in the treatment of coronary artery diseases without significant complications and target vessel revascularization.

Effects of Antiplatelet Agents in the Prevention of Ventricular Tachyarrhythmias during Acute Myocardial Ischemia in the Rats

BACKGROUND: Aspirin, one of the antiplatelet agents, improves the survival rate after myocardial infarction. This beneficial effect is known to be obtained in part by the antiarrhythmic action of aspirin. It is not known whether other antiplatelet agents have such effects. This study was performed to compare the effects of aspirin, ticlopidine, and abciximab (platelet glycoprotein IIb/IIIa receptor antagonist) on the ischemia-induced arrhythmias with a rat model of cardiac regional ischemia. METHODS: Experiments were performed in 4 groups of rats. The 4 groups were as follows : control, n=10:aspirin-pretreated, 300 mg/kg po for 1 week:ticlopidine-pretreated, 200 mg/kg po for 1 wk:abciximab-pretreated, 2 mg/kg iv 10-20 minutes before experiment. The electrocardiogram and blood pressure were recorded during 20 minutes. The time to the onset of ST-segment elevation and ventricular tachyarrhythmias, frequency and incidence of ventricular tachyarrhythmias, and death rate were assessed during acute myocardial ischemia induced by ligation of proximal left anterior descending coronary artery in anesthetized rats. RESULTS: Platelet aggregations to ADP were significantly lower in aspirin (42.8%), ticlopidine (43.8%), and abciximab group (34.0%) than in control group (66.4%). The frequencies of sustained ventricular tachycardia (VT) were 6.8+/-3.6 in control, 3.6+/-3.8 aspirin, 4.7+/-3.7 ticlopidine, and 1.4+/-2.5 abciximab group. The frequency of sustained VT in the abciximab group was significantly lower than in control group. The incidences of ventricular arrhythmias for 20 min were 10/10 for VT and 8/10 for ventricular fibrillation (VF) in control group, 7/10 for VT and 3/10 for VF in aspirin group, 10/10 for VT and 3/10 for VF in ticlopidine group, and 5/10 for VT and 4/10 for VF in abciximab group. The incidences of cardiac death during 20 min were 8/10 in control group, 4/10 in aspirin group, 2/10 in ticlopidine group and 5/10 in abciximab group. The incidence of VT in the abciximab group was significantly lower than in control group, incidences of VF in the aspirin and ticlopidine groups were significantly lower than in control group, and death rate in ticlopidine group was significantly lower than in control group. CONCLUSION: The present study suggested that aspirin, ticlopidine, and abciximab could prevent ventricular tachycardia or ventricular fibrillation in a rat model of cardiac regional ischemia and their antiarrhythmic effects improve the survival rate.

Effects of Antiplatelet Agents in the Prevention of Ventricular Tachyarrhythmias during Acute Myocardial Ischemia in the Rats

BACKGROUND: Aspirin, one of the antiplatelet agents, improves the survival rate after myocardial infarction. This beneficial effect is known to be obtained in part by the antiarrhythmic action of aspirin. It is not known whether other antiplatelet agents have such effects. This study was performed to compare the effects of aspirin, ticlopidine, and abciximab (platelet glycoprotein IIb/IIIa receptor antagonist) on the ischemia-induced arrhythmias with a rat model of cardiac regional ischemia. METHODS: Experiments were performed in 4 groups of rats. The 4 groups were as follows : control, n=10:aspirin-pretreated, 300 mg/kg po for 1 week:ticlopidine-pretreated, 200 mg/kg po for 1 wk:abciximab-pretreated, 2 mg/kg iv 10-20 minutes before experiment. The electrocardiogram and blood pressure were recorded during 20 minutes. The time to the onset of ST-segment elevation and ventricular tachyarrhythmias, frequency and incidence of ventricular tachyarrhythmias, and death rate were assessed during acute myocardial ischemia induced by ligation of proximal left anterior descending coronary artery in anesthetized rats. RESULTS: Platelet aggregations to ADP were significantly lower in aspirin (42.8%), ticlopidine (43.8%), and abciximab group (34.0%) than in control group (66.4%). The frequencies of sustained ventricular tachycardia (VT) were 6.8+/-3.6 in control, 3.6+/-3.8 aspirin, 4.7+/-3.7 ticlopidine, and 1.4+/-2.5 abciximab group. The frequency of sustained VT in the abciximab group was significantly lower than in control group. The incidences of ventricular arrhythmias for 20 min were 10/10 for VT and 8/10 for ventricular fibrillation (VF) in control group, 7/10 for VT and 3/10 for VF in aspirin group, 10/10 for VT and 3/10 for VF in ticlopidine group, and 5/10 for VT and 4/10 for VF in abciximab group. The incidences of cardiac death during 20 min were 8/10 in control group, 4/10 in aspirin group, 2/10 in ticlopidine group and 5/10 in abciximab group. The incidence of VT in the abciximab group was significantly lower than in control group, incidences of VF in the aspirin and ticlopidine groups were significantly lower than in control group, and death rate in ticlopidine group was significantly lower than in control group. CONCLUSION: The present study suggested that aspirin, ticlopidine, and abciximab could prevent ventricular tachycardia or ventricular fibrillation in a rat model of cardiac regional ischemia and their antiarrhythmic effects improve the survival rate.

The Effects of Therapeutic Duration of Combined Antiplatelets, Aspirin and Ticlopidine, on Coronary Stent Restenosis

BACKGROUND: One of most important mechanisms of coronary stent restenosis is neointimal hyperplasia. Although the process of neointima formation is not fully understood, a special role has been advocated for adherent platelets. Previous studies have shown a clear benefit with combined antiplatelet therapy such as aspirin plus ticlopidine in reducing the rate of thrombotic occlusions of stented vessels. The purpose of this study was to evaluate the effects of duration of antiplatelet regimens on coronary stent restenosis. METHODS: After successful placement of coronary artery stents in 222 patients, we performed follow-up coronary angiograms in 99 patients (42.3%). Forty-six patients were randomly assi-gned to receive aspirin and ticlopidine for four weeks (Group I: 54+/-9 years: M 38, F 8) and 48 patients for 6 months (Group II: 58+/-8 years: M 38, F 10). RESULTS: There were no significant differences in clinical and procedural variables or coronary lesion characteristics before and after stenting. At 6 months after stenting, minimal luminal diameter was 2.16+/-0.93mm in Group I and 2.04+/-1.07mm in Group II (p-0.57). Late lumen loss was 0.80+/-1.07mm in Group I and 0.92+/-1.11mm (p-0.58) in Group II. The stent restenosis rate of Group I at 28.3% and that of Group II at 29.2% were not statistically significant between the two groups (p-0.92). CONCLUSIONS: The therapeutic duration of combined antiplatelet regimen with aspirin and ticlopidine after coronary stent does not affect stent restenosis rate.

Effective Approaches to Successful Target Sites in Catheter Ablation of the Right-side Accessory Pathways / 대한내과학회지

BACKGROUND: Although radiofrequency catheter ablation (CA) of the accessory pathway (AP) is very effective and safe, it has been reported that CA is more difficult in the right-side AP than the left-side AP, requiring the refinement of the conventional CA technique for the right-side AP. This study was, therefore, aimed to develop an effective technique for CA of the right-side AP. METHODS: Fifty right-side APs in 45 patients which underwent CA were included in this study. The locations of APs were divided into 8 regions (anteroseptal, mid septal, posteroseptal, posterior, posterolateral, lateral, anterolateral, and anterior). After localizing APs, CA of the APs was attempted via the inferior vena cava (IVC) in all patients. If CA attempt via the IVC for more than 1 hour was failed, then CA was tried via the superior vena cava (SVC). Successful CA was defined as permanent loss of AP conduction even during infusion of isoproterenol (1-4microg/min). The ways of approaching the ablation catheter to the successful target sites were classified into over-the-tricuspid valve approach (OV) via the IVC (IVC-OV), OV via the SVC (SVC-OV), under-the-tricuspid valve (UV) approach via the IVC (IVC-UV), and UV via the SVC (SVC-UV) and evaluated according to the AP locations. RESULTS: The locations of the APs were anteroseptal in 5 APs, mid septal in 6, posteroseptal in 12, posterior in 3, posterolateral in 5, right lateral in 11, anterolateral in 4, and anterior in 4. Forty-eight (96.0%) of 50 APs were successfully ablated; 35 (70.0%) with primary IVC approaches and 13 (26.0%) with secondary SVC approaches. As a successful approach, IVC-OV was 26 (54.2%); IVC-UV, 9 (18.8%); SVC-OV, 4 (8.3%), and SVC-UV, 9 (18.8%). Secondary SVC approaches were required 7 (70.0%) in the lateral APs, 2 (50.0%) in the anterolateral APs, 1 (25.0%) of the posterolateral APs, 1 (25.0%) in the anterior APs, 1 (20.0%) of the anteroseptal APs, and 1 (8.3%) in the posteroseptal APs but none in the midseptal and posterior APs. SVC-UV approach was used in 9 (69.2%) in 13 APs which were ablated with SVC approach. CONCLUSIONS: The ways of approach to successful target site in CA of the right-side APs are different according to the location and SVC approaches are frequently required in ablation of the lateral or anterolateral APs. Therefore, SVC approaches should be considered in these locations if the initial IVC approaches are not successful.

Usefulness of a "Push Technique" for Atrial Lead Implantation

BACKGROUND AND OBJECTIVES: Dual-chamber pacing is commonly used as a pacing mode maintaining at-rioventricular synchrony. However, traditional technique for atrial J lead implantation is relatively time-consuming and not easy to get optimal sites for both atrial and ventricular leads, especially for less-experienced operators. We developed a new "push technique" for atrial J lead implantation. MATERIALS AND METHOD: This study included sixty-two consecutive patients (26 males 36 females, 55+/-10 years, 56 patients received DDD and 6 received AAI pacemakers) from Jan. 1992 through Dec. 1996. Atrial J leads were implanted using a "push technique", that is, simply advancing a straightened lead while holding the stylet in the pacing lead at the junction of the superior vena cava and the right atrium. We evaluated the early and long-term result of atrial J lead implantation by the "push technique". RESULTS: 1) Atrial leads were successfully inserted by the first or second trial of the "push technique" in the 62 patients (100%). The sensed P wave amplitude was 3.1+/-1.0 mV, pacing threshold 0.6+/-0.2 V at the pulse width of 0.5 ms, impedance 547.4+/-118.5 ohms at 5 V. 2) During follow-up of 28.1+/-15.7 months, significant changes in the pacing parameters and the dislodgement of atrial leads were not seen. CONCLUSION: The early and long-term result of atrial J lead implantation by the "push technique" was excellent. This "push technique" can be used as an easy alternative technique for atrial J lead implantation.

Electrophysiologic Factors Responsible for the Induction of AV Nodal Reentrant Tachycardia / 대한내과학회지

OBJECTIVES: Although a subtle balance between conduction time of the antgrade slow pathway and refractory period of the retrograde fast pathway is known to play the most critical role in the induction of AV nodal reentrant tachycardia(AVNRT), other electrophysiologic factors such as concealed conduction in to the fast pathway have been suggested to be responsible. The present study was performed to determine the electrophysiologic factors responsible for the induction of AVNRT. METHODS: Total 34 subjects undergoing electrophysiologic study(EPS) including 9 normal subjects(SAVNP), 7 subjects with dual AV nodal pathways(DAVNP) but no inducible AVNBT, and 18 inducible AVNRT patients were included in this study. EPS was performed using the conventional technique. To evaluate the presence of concealed conduction into the fast AV nodal pathway(FP) and its effects on the effective refractory period(ERP) of the FP (FP-ERP) to a subsequent impulse, single(A2) and double atrial extrastimuli(A2A3) were given. FP-ERP of conducted A2 [FP-ERP-A2(+)] was measured with a second atrial extrastimulus(A3) following a first atrial extrastimulus(A2), which was delivered at a coupling interval 20-30ms longer than FP-ERP. ERPs of non-conducted A2 [FP-ERP-A(-)] was measured with A3 following A2 at coupling intervals 20 ms shorter than FP-ERP. Concealed conduction was considered to be present when A1A3 interval of A3 blocked at the FP with a longest A2A3 interval was longer than FP-ERP. Concealment index(CI)-1 and CI-2 were calculated by dividing FP-ERP-A2(-) by FP-ERP-A2(+) and FP-ERP, respectively. In addition, relationship between antegrade slow pathway conduction time(A2H2) and retrograde fast pathway conduction time(HA), retrograde AV conduction system block cycle length(VA-BCL), and retrograde AV conduction system EBP(VA-ERP) was evaluated by a regression analysis. RESULTS: Concealed conduction was present in all the subjects. CI-1 was 0.63 +/- 0.04 and CI-2, 0.79 +/- 0.04 in SAVNP and 0.67 +/- 0.11, 0.68 +/- 0.07 respectively, in AVNRT patients in whom the antegrade slow pathway(SP) was ablated with catheter ablation, showing no significant difference in CI between 2 groups. At the time of induction of AVNRT with A2, A2H2. was significantly correlated with FP-ERP and FP-CT(r=OA43, p=0.04; r=0.507, p=0,02, respectively). By multivariate regression analysis, it was derived that A2H2 should be greater than "0.79 FP-ERP+1.57 FP-CT-0.44 HA-190(ms)" (r=0.71, p<0.05). CONCLUSION: Induction of typical AVNRT with A2 is determined by conduction time of the slow pathway, refractory period and conduction velocity of the fast pathway, and concealed conduction into the fast pathway.

Successful Coronary Stent Implantation without Systemic Heparin Therapy: Use of Local Heparin Delivery

BACKGROUND: Acute or subacute stent thrombosis, bleeding complications and restenosis remain major clinical concerns in coronary stenting despite high pressure inflation and intravascular ultrasound guidance. A new strategy of local heparin delivery may maintain sustained local concentration and limit systemic complications. To observe the feasibility and efficacy of local heparin delivery in stenting, local heparin deliveries were performed in stented patients. METHOD: Heparin was delivered(5,000 Units, 1.0ml/min over 10 min) using the Dispatch Catheter, after predilation of target lesons in 10 patients(4 unstable angina, 6 acute myocardial infarction, mean age 52+/-7 yr) in the left anterior descending artery without systemic heparin loading. After local heparin delivery. Palmaz-Schatz stents were placed using standard methods. APTT and CK were checked at 1hr, 3hrs and 24 hrs after local heparin delivery and stenting. Follow-up coronary angiograms were done at 48 hrs and 6 months after stenting. RESULTS: All patients had no ischemic symptoms or ECG changes during and after local heparin delivery. All APTT and CK values were unchanged at 3 hrs and 24 hrs after local heparin delivery and stenting. Follow-up quantitative coronary angiograms at 48 hrs and 6 months showed all stents patent, with TIMI III distal flow, and without intra-stent thrombus(%diameter stenosis : 79.4+/-4.2% before predilation, 32.9+/-7.7% after predilation, 32.4+/-13.1% after local delivery, 14.2+/-2.3% immediately after stenting, 13.9+/-2.5% at 48 hrs and 21.7+/-8.8% at 6 months after stenting). CONCLUSION: Intracoronary stenting may be performed safely and effectively without systemic heparin therapy by using local heparin prior to stent implantation. Long-term stent patency and lack of coronary events appear favorable.

A Study on Electrophysiologic Mechanism and Clinical Characteristics of Paroxysmal Supraventricular Tachycardia / 대한내과학회지

OBJECTIVES: Accurate diagnosis of the mechanism and origin site of paroxysmal supraventricular tachycardia(PSVT) can be made using electrophysiologic study(EPS). Recently, radiofrequency catheter ablation technique has been introduced and widely used for the definitive treatment of various forms of PSVT, thereby precise determination of the mechanism of PSVT can be possible. It has been known that atrioventricular reentry tachycardia (AVRT) using concealed bypass tract is more frequent than atrioventricular nodal reentry tachycardia (AVNRT) in Korea. But it is not certain that those studies represent actual distribution of PSVT in Korea. This study was designed to determine the mechanism and clinical characteristics of PSVT in Korea. METHODS: We investigated 136patients in whom electrophysiolosic study was performed from October 1992 through October 1994 at the Chonnam National University Hospital, the only tertiary referral center of the Kwangju-Chonnam area of Korea. RESULTS: 1) The electrophysiologic mechanism of PSVT was AVNRT in 44patients(32.4%), WPW syndrome in 46(33.8%), AVRT using concealed bypass tract in 40(29.4%), sinoatrial nodal reentry tachycardia (SANRT) in 4(2.9%), and automatic atrial tachycardia(AAT) in 2(1.5%), ensuing that AVNRT is most common mechanism of PSVT with no preexcitation during sinus rhythm. 2) Male is more frequent than female in AVNRT, WPW syndrome, and AVRT, which was most prominent in WPW syndrome. 3) The first episode of symptom occured at the age of 34.9 +/- 17.3 years in AVNRT, 25.5 +/- 13.3 years in WPW and 26.3 +/- 15.0 years in AVRT(p<0.05). There was no significant difference in the duration of symptom. The tachycardia rate in WPW syndrome was 183.6 +/- 23.9 per minute and AVRT was 186.7 +/- 38.0 per minute, which were faster than that of AVNRT(161.7 +/- 28.6/min)(p<0.05). 4) There was no significant difference in the presenting symptoms and in the provocation factors between AVNRT and AVRT. CONCLUSION: AVNIlT is most common mechanism of PSVT with no preexcitation during sinus rhythm, developed at older age than WPW syndorme and AVRT, and had lower tachycardia rate than WPW syndrome and AVRT.