EXPERIMENTAL STUDY ON PERI AV-NODAL AUTOMATICITY AFTER ATRIOVENTRICULAR INTERRUPTION (AV INTERRUPTION) IN CANINE DENERVATED HEART : PROCEEDINGS OF THE 47th ANNUAL SCIENTIFIC MEETING OF THE JAPANESE CIRCULATION SOCIETY : Electrophysiology (I)
スポンサーリンク
概要
- 論文の詳細を見る
- 社団法人日本循環器学会の論文
- 1983-08-20
著者
-
KOYANAGI HITOSHI
Heart Institute of Tokyo Women's Medical College
-
Koyanagi Hitoshi
Heart Center St. Luke's International Hospital
-
Kasanuki Hiroshi
Heart Institute of Japan, Tokyo Women's Medical College
-
Koyanagi Hitoshi
The Department Of Cardiovascular Surgery The Heart Institute Of Japan Tokyo Women's Medical Uni
-
Yagi Yoko
Department Of Cardiovascular Surgery Heart Institute Of Japan Tokyo Women's Medical College
-
Yagi Yoko
Heart Institute of Japan, Tokyo Women's Medical College, Hukuyama cardiovascular Hospital
-
Kasanuki Hiroshi
Heart Institute Of Japan Department Of Cardiology (hijc) Tokyo Women's Medical University
-
Kurosawa Hiromi
Heart Institute of Japan, Tokyo Women's Medical College
-
Yagi Youko
Department Of Cardiology The Heart Institute Of Japan Tokyo Women's Medical College
-
Yagi Yoko.
Department Of Cardiology The Heart Institute Of Japan Tokyo Women's Medical College
-
Kasanuki Hiroshi
Department Of Cardiovascular Surgery Heart Institute Tokyo Women's Medical University
-
Hirosawa Koshichira
Department Of Cardiovascular Surgery The Heart Institute Of Japan Tokyo Women's Medical Univers
-
Kasanuki H
Department Of Cardiovascular Surgery The Heart Institute Of Japan Tokyo Women's Medical Univers
関連論文
- The Japanese Society of Hypertension Committee for Guidelines for the Management of Hypertension
- PJ-746 Clinical Characteristics in Acute Heart Failure Syndromes Patients with and without Atrial Fibrillation : A Preliminary Report from ATTEND Registry(PJ125,Preventive Medicine/Epidemiology/Education 3 (H),Poster Session (Japanese),The 73rd Annual Sci
- PJ-331 Day and Time of Admission, Clinical Characteristics, and Outcomes in Acute Heart Failure Syndromes : A Report from the ATTEND Registry(PJ056,Preventive Medicine/Epidemiology/Education 2 (H),Poster Session (Japanese),The 73rd Annual Scientific Meeti
- 2 Refractory VT/VF, Prospective Evaluation to Differentiate Lidocaine Efficacy from Nifekalant : RELIEF Study(Late Breaking Clinical Trials I,The 73rd Annual Scientific Meeting of The Japanese Circulation Society)
- FRS-112 Influence of the Early Ticlopidine Discontinuation on Clinical Outcomes following Sirolimmus-Eluting Stent Implantation(FRS23,Clinical Evidence of DES Era (1) (IHD),Featured Research Session (English),The 73rd Annual Scientific Meeting of The Japa
- FRS-111 Contemporary Practice Use of Sirolimus-Eluting Stents in Hemodialysis Patients : The Results from HIJ-DES Registry(FRS23,Clinical Evidence of DES Era (1) (IHD),Featured Research Session (English),The 73rd Annual Scientific Meeting of The Japanese
- 2 Prognostic Factors in Patients with Coronary Artery Disease Treated with Sirolimus-eluting Stent : The HIJ-DES registry(Current Status and Future Perspective of Drug-Eluting Stents,Plenary Session 1 (PL-1) (A),The 73rd Annual Scientific Meeting of The J
- PJ-823 The evaluation of angiographic restenotic pattern after sirolimus-eluting stents implantation in patients on hemodialysis : From the HIJC DES Registry(Coronary revascularization, PCI(26)(IHD),Poster Session(Japanese),The 72nd Annual Scientific Meet
- -145- CLINICAL CONSIDERATION OF LEFT VENTRICULAR ASSIST SYSTEM FOR CARDIOGENIC SHOCK AFTER ACUTE MYOCARDIAL INFARCTION : Myocardial Infarction, Valvular Heart Disease : FREE COMMUNICATIONS(I) : PROCEEDINGS OF THE 51th ANNUAL SCIENTIFIC MEETING OF THE JAPA
- PE-210 Ca antagonist, Nifedipine, Inhibits Human Monocyte Cox-2 Expression and Thromboxane Synthesis Induced by Activated Platelets.(Infection/Inflammation/Immunity(02)(H),Poster Session(English),The 72nd Annual Scientific Meeting of the Japanese Circulat
- OJ-168 Incidence of death from of hemorrhage among Japanese patients treated with warfarin for mechanical valve replacement : Comparison for endemic rate(Thromboembolism / Antithrombotic therapy / Thrombolysis(02)(H),Oral Presentation (Japanese),The 72nd
- PJ-148 Aspirin-resistant Tromboxane Biosynthesis via Introducing Platelet COX-2 Expression in Patients with Acute Coronary Syndrome(Acute coronary syndrome, basic/clinical-8, The 71st Annual Scientific Meeting of the Japanese Circulation Society)
- PJ-139 Significant Increase of Anticoagulation-related Bleeding in Patients Requiring Lower Warfarin Dosage to Achieve Therapeutic Anticoagulation(Thromboembolism/Antithrombotic therapy/Thrombolysis-4, The 71st Annual Scientific Meeting of the Japanese Ci
- PJ-083 Long-term Results of Dual-chamber (DDD) Pacing in Symptomatic Hypertrophic Obstructive Cardiomyopathy (HOCM)(Cardiac function, basic/clinical-3, The 71st Annual Scientific Meeting of the Japanese Circulation Society)
- PJ-348 Utility of ECG-gated MDCT to Differentiate Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) from Ventricular Tachyarrhythmia(PJ059,CT/MRI (Myocardium) 1 (I),Poster Session (Japanese),The 73rd Annual Scientific Meeting of The Japanese Circulat
- PJ-200 Depression Persists in Patients with Implantable Cardioverter Defibrillator in Long Term(PJ034,Stress-psychosomatic Medicine (H),Poster Session (Japanese),The 73rd Annual Scientific Meeting of The Japanese Circulation Society)
- OJ-015 Psycological distress in patients with Implantable Cardioverter Defibrillator(Autonomic nervous system(02)(H),Oral Presentation(Japanese),The 72nd Annual Scientific Meeting of the Japanese Circulation Society)
- Role of Systemic Inflammation and Glycemic Control for Aspirin-Resistant Thromboxane Biosynthesis in Patients with Coronary Artery Disease (Angina Pectoris, Basic/Clinical 2 (IHD), The 69th Annual Scientific Meeting of the Japanese Circulation Society)
- PJ-064 Evaluation of Myocardial Damage by Magnetic Resonance Imaging in Patients with Duchenne Muscular Dystrophy(PJ011,CT/MRI (Myocardium) 4 (I),Poster Session (Japanese),The 73rd Annual Scientific Meeting of The Japanese Circulation Society)
- OJ-209 Localization of Mitral Valve Prolapse Affects the Geometry of the Mitral Annulus(OJ35,Valvular Heart Disease/Pericarditis/Cardiac Tumor 1 (M),Oral Presentation (Japanese),The 73rd Annual Scientific Meeting of The Japanese Circulation Society)
- 6 Prevalence and Characteristics of Depression in Cardiovascular Patients in Japan(Is Stress a Risk of Cardiovascular Disease?,Symposium 22 (SY-22) (I),The 73rd Annual Scientific Meeting of The Japanese Circulation Society)
- PE-359 A New Index of Diastolic Dysfunction in Mitral Regurgitation(PE060,Valvular Heart Disease (M),Poster Session (English),The 73rd Annual Scientific Meeting of The Japanese Circulation Society)
- Successful treatment of a patient with severe pulmonary hypertension due to perivalvular leakage at aortic and mitral positions after aortic and mitral valve replacement
- Fibroblast sheets co-cultured with endothelial progenitor cells improve cardiac function of infarcted hearts
- PJ-883 Usefulness of Non-invasive Hemodynamic Measurement in the Clinic for the Choice of Optimum Antihypertensive Drug in Essential Hypertension(Hypertension, clinical(10)(H),Poster Session(Japanese),The 72nd Annual Scientific Meeting of the Japanese Cir
- PJ-191 The effect of aortic root surgery on the hemodynamics in aortic regurgitation(Valvular heart disease/Pericarditis/Cardiac tumor(03)(M),Poster Session(Japanese),The 72nd Annual Scientific Meeting of the Japanese Circulation Society)
- PJ-162 Significant Effects of EPA on Aortic Medial Calcification in the Vascular Calcification Model Rats(Peripheral circulation/Vascular disease(06)(H),Poster Session(Japanese),The 72nd Annual Scientific Meeting of the Japanese Circulation Society)
- PE-154 Dehydroepiandrosterone-sulfate (DHEAS) Deficiency Contributes to CD4T Cell-Induced Endothelial Apoptosis in Perimenopausal Women(Atherosclerosis, basic(04)(IHD),Poster Session(English),The 72nd Annual Scientific Meeting of the Japanese Circulation
- PE-125 Soluble TRAIL in Peripheral Blood is a Novel Marker for Acute Coronary Syndromes(Acute coronary syndrome, basic/clinical(03)(IHD),Poster Session(English),The 72nd Annual Scientific Meeting of the Japanese Circulation Society)
- PE-111 Ten years long-term prognostic evaluation by I-123 MIBG scintigraphy in dilated cardiomyopathy(Nuclear cardiology(03)(I),Poster Session(English),The 72nd Annual Scientific Meeting of the Japanese Circulation Society)
- PE-028 Roles of TRAIL-Expressing CD4 T Cells and its Receptor DR5 in Vulnerable Plaque(Atherosclerosis, basic(03)(IHD),Poster Session(English),The 72nd Annual Scientific Meeting of the Japanese Circulation Society)
- OE-238 Adult Murine Heart Derived Clonal Expanded Sca-1 Positive Cell Sheet Ameliorates Cardiac Dysfunction after Myocardial Infarction(Regeneration(angiogenesis/myocardial regeneration)(01)(M),Oral Presentation(English),The 72nd Annual Scientific Meeting
- Factors Governing Re-Infarction in Patients with Myocardial Infarction in Japan
- Follow-up of 2, 733 Japanese Patients with Myocardial Infarction
- REVIEW OF 50 CASES OF AORTITIS SYNDROME ESPECIALLY ON CARDIAC AND PULMONARY ARTERY INVOLVEMENT : (Part II)
- Percutaneous Transluminal Coronary Angioplasty for Postoperative Left Coronary Artery Stenosis Following Surgical Reconstruction of Congenital Atresia of the Left Main Coronary Artery
- Management of late atrial tachyarrhythmia long after Fontan operation
- PJ-745 How do You Act in Case of Acute Chest Sipmptoms : Questionare for Patients with Coronary Risk Factors(PJ125,Preventive Medicine/Epidemiology/Education 3 (H),Poster Session (Japanese),The 73rd Annual Scientific Meeting of The Japanese Circulation So
- PE-201 Vector-projected 187-channel Electrocardiogram can Evaluate an Alternance of T-wave Current Density and Disptribution(PE034,ECG/Body Surface Potential Mapping/Holter (A),Poster Session (English),The 73rd Annual Scientific Meeting of The Japanese Ci
- PE-194 The Initial Experience of Transvenous Leads Extraction Assisted by the Excimer Laser System(PE033,Arrhythmia, Others (Clinical/Diagnosis/Treatment) 3 (A),Poster Session (English),The 73rd Annual Scientific Meeting of The Japanese Circulation Societ
- PE-048 Insulin Treatments Overweigh the Beneficial Effect of Sirolimus Eluting Stent(PE008,Coronary Revascularization, PCI (DES) 1 (IHD),Poster Session (English),The 73rd Annual Scientific Meeting of The Japanese Circulation Society)
- PJ-792 The Clinical Predictors of High Defibrillation Threshold in Implantable Cardioverter Defibrillators : Is there hint in the Chest X-ray?(Arrhythmia, therapy(22)(A),Poster Session(Japanese),The 72nd Annual Scientific Meeting of the Japanese Circulati
- PJ-788 Measures for the Patients with High Defibrillation Threshold and the Outcome(Arrhythmia, therapy(22)(A),Poster Session(Japanese),The 72nd Annual Scientific Meeting of the Japanese Circulation Society)
- PJ-761 Glycated Hemoglobin and Risk of Cardiovascular Events in Patients without Diabetes in the Heart Institute of Japan Acute Myocardial Infarction(Acute myocardial infarction, clinical(diagnosis / treatment)(12)(IHD),Poster Session(Japanese),The 72nd A
- PJ-650 Predictors of Restenosis in the Patients with Hemodialysis who Underwent Coronary Intervention with Sirolimus Eluting Stents(Coronary revascularization, PCI(23)(IHD),Poster Session(Japanese),The 72nd Annual Scientific Meeting of the Japanese Circul
- Hemodynamic Response to Exercise in Patients 2 to 6 Years after Rastelli Operation
- PULMONARY HYPERTENSION IN COMPLETE TRANSPOSITION OF THE GREAT ARTERIES ASSOCIATED WITH VENTRICULAR SEPTAL DEFECT : Congenital Heart Disease : PROCEEDINGS OF THE 50th ANNUAL SCIENTIFIC MEETING OF THE JAPANESE CIRCULATION SOCIETY
- JUXTA-DUCTAL LEFT PULMONARY ARTERY STENOSIS IN PULMONARY ATRESIA : ANGIOGRAPHIC FINDINGS, NATURAL HISTORY AND MORPHOGENESIS : Congenital Heart Disease, Kawasaki Disease : FREE COMMUNICATIONS (VI) : PROCEEDINGS OF THE 49th ANNUAL SCIENTIFIC MEETING OF THE
- 2 Management of "Anticipated" Admissions in Adult Congenital Heart Disease Clinic(Patient Menagement System for Adult Congenital Heart Disease,Symposium 19 (SY-19) (M),The 73rd Annual Scientific Meeting of The Japanese Circulation Society)
- Anatomy and Surgical Treatment of Endocardial Cushion Defect
- PJ-268 Quantitative analysis of the coronary artery stent's inside diameter in 16 Slice MDCT(X-ray/CT/MRI/DSA4 (I) : PJ45)(Poster Session (Japanese))
- PE-048 Percutaneous Closure of Interatrial Communications in Patients with Presumed Paradoxical Embolism for Secondary Prevention(Thromboembolism/Thrombolysis 1 (IHD) : PE9)(Poster Session (English))
- OJ-158 Transmural Extent of Delayed-hyperenhancement on MRI predicts Left Ventricular Function in Subacute and Chronic Phase in Reperfused Anterior Myocardial Infarction(X-ray/CT/MRI/DSA2 (I) : OJ19)(Oral Presentation (Japanese))
- Insight for Treating Aortic Intramural Hematoma : Location of Entry Site Still Can Predict Clinical Outcome and Need for Surgery
- Effectiveness and Safety of ATP Stress Perfusion MR Imaging Compared with Exercise Stress Scintigraphy to Evaluate De-Novo Coronary Artery Lesions
- Clinical Characteristics and Outcome of Hospitalized Patients With Congestive Heart Failure : Results of the HIJC-HF Registry
- Surgery of Ascending Aorta and/or Aortic Arch Using Deep Hypothermic Circulatory Arrest with Retrograde Cerebral Perfusion and Open Technique
- Use of Arterial Grafts for Coronary Revascularization : Experience of 2987 Anastomoses
- Surgery for Complications Due to Myocardial Infarction : 50th Annual Scientific Session of the Japanese Circulation Society
- -361- "EPICARDIAL APPROACH" FOR WPW SYNDROME (TYPE A) WITHOUT CARDIOPULMONARY BYPASS
- -279-SURGICAL THERAPY FOR VENTRICULAR TACHYCARDIA/FIBRILLATION ASSOCIATED WITH VENTRICULAR ANEURYSM
- 2 How to Promote Coexistence of Child Raising and Medical Research for Female Cardiologists(How to Avoid Women Cardiologists from Quitting Their Job,Symposium 20 (SY-20) (A),The 73rd Annual Scientific Meeting of The Japanese Circulation Society)
- Fibroblast Cell Sheets Co-cultured with Endothelial Progenitor Cells Improve Cardiac Function of Infarcted Heart(Tissue Engineering (H), The 69th Annual Scientific Meeting of the Japanese Circulation Society)
- PE-087 Growth hormone promotes hypertrophy of the myocardial tissue graft(Tissue Engineering (H) : PE15)(Poster Session (English))
- THE CHANGE IN BREATHING PATTERN ASSOCIATED WITH PULMONARY HYPERTENTION IN MITRAL STENOSIS : Valvular Heart Disease, Pulmonary Circulation : FREE COMMUNICATIONS (VI) : PROCEEDINGS OF THE 49th ANNUAL SCIENTIFIC MEETING OF THE JAPANESE CIRCULATION SOCIETY
- Familial Sick Sinus Syndrome With Atrioventricular Conduction Disturbance
- MEASUREMENT OF AORTIC VALVE PRESSURE GRADIENT WITHOUT INSERTING A CATHETER INTO THE LEFT VENTRICLE : Valvular Heart Disease, Pulmonary Circulation : FREE COMMUNICATIONS (VI) : PROCEEDINGS OF THE 49th ANNUAL SCIENTIFIC MEETING OF THE JAPANESE CIRCULATION S
- PHONOCARDIOGRAPHIC AND ANGIOCARDIOGRAPHIC EVALUATION OF VALVE OPENING OF MITRAL BIOPROSTHESIS : Valvular Heart Disease, Extracorporeal Circulation : III : 48 Annual Scientific Meeting, Japanese Circulation Society
- -0283-EFFICACY AND INDICATION OF SURGICAL MODIFICATION OF ATRIOVENTRICULAR NODAL CONDUCTION TO TREAT VARIOUS KINDS OF PAROXYSMAL SUPRAVENTRICULAR TACHYCARDIAS
- CLASSIFICATION OF THE SICK SINUS SYNDROME ACCORDING TO OVERDRIVE SUPPRESSION : Ist Auditorium : PROCEEDINGS OF THE 40TH ANNUAL MEETING OF THE JAPANESE CIRCULATION SOCIETY
- Efficacy and Limitations of CCU : from Surgical Standpoints : The Effectiveness and Limitations of Coronary Care Unit
- St. Jude Medical Prosthetic Aortic Valve Malfunction Due to Pannus Formation
- Mid-Term Follow Up Results of Japanese Heart Transplant Patients Operated in UCLA Medical Center
- Effects of Immunosuppressants on Platelet-Derived Growth Factor-A Chain mRNA Expression and Coronary Arteriosclerosis in Rat Cardiac Allografts
- IS029 EXPERIENCE OF HEART REPLACEMENT FOR THE PATIENTS WITH END-STAGE OF CARDIAC FAILURE
- -P48-NONINVASIVE DETECTION OF REJECTION OF RAT'S TRANSPLANTED HEARTS WITH IODINE-125-LABELED ANTI-MYOSIN ANTIBODY : RI : FREE COMMUNICATIONS(III) : PROCEEDINGS OF THE 53th ANNUAL SCIENTIFIC MEETING OF THE JAPANESE CIRCULATION SOCIETY
- Echocardiographically Evaluated Site of Attachment of Atrial Myxoma May Predict Recurrence
- ON THE POSSIBILITY OF SAVING PATIENTS WITH VENTRICULAR FREE WALL RUPTURE FOLLOWING ACUTE MYOCARDIAL INFARCTION : Ischemic Heart Disease (III) : III : 48 Annual Scientific Meeting, Japanese Circulation Society
- ISOZYMIC CHANGES IN MYOSIN OF HUMAN VENTRICULAR MYOCARDIUM INDUCED BY OVERLOAD. IMMUNOHISTOCHEMICAL STUDY USING MONOCLONAL ANTIBODY : Myocardial Biochemistry : PROCEEDINGS OF THE 50th ANNUAL SCIENTIFIC MEETING OF THE JAPANESE CIRCULATION SOCIETY
- Biventricular Pacing Reduces Ventricular Arrhythmias in Patients with Severe Chronic Heart Failure
- Survival Improvement with Combination Therapy of Implantable Cardioverter-Defibrillator and β Blockers in Patients with Life-Threatening Ventricular Arrhythmias
- CHANGES OF SKIN TEMPERATURE AFTER PERCUTANEOUS TRANSVENOUS MITRAL COMMISSUROTOMY (PTMC) : Pulmonary, Peripheral, Cerebral Circulation : 53 Annual Scientific Meeting, Japanese Circulation Society
- SURGICAL TREATMENT FOR REFRACTORY ECTOPIC ATRIAL TACHYCARDIA : Arrhythmias : 53 Annual Scientific Meeting, Japanese Circulation Society
- The Role of Prosthetic Valves in the Treatment of Valvular Disease of the Heart : With Particular Attention to the Quality of Life after Valve Replacement : PANEL DISCUSSION ON VARIOUS PROBLEMS IN VALVE REPLACEMENT
- USEFULNESS OF ELECTROPHYSIOLOGIC STUDY FOR LOCATING MULTIPLE KENT BUNDLES : Arrhythmias : 53 Annual Scientific Meeting, Japanese Circulation Society
- -210-DIAGNOSIS OF THE SITE OF KENT'S BUNDLE BY BODY SURFACE MAPPING : AN EXPERIMENTAL STUDY USING IN SITU ISOLATED BEATING HEART MODEL
- EXPERIMENTAL STUDY ON INTRAATRIAL CONDUCTION DISTURVANCE AND SECONDARY PACEMAKER AFTER ATRIAL INCISION OR EXCISION : Arrhythmias (IV) : FREE COMMUNICATIONS (VI) : PROCEEDINGS OF THE 49th ANNUAL SCIENTIFIC MEETING OF THE JAPANESE CIRCULATION SOCIETY
- CLINICAL SIGNIFICANCE OF NONPHARMACOLOGICAL THERAPY FOR VENTRICULAR TACHYARRHYTHMIAS IN PATIENTS WITH DILATED CARDIOMYOPATHY
- -1176-NON-INVASIVE DETECTION OF REJECTION OF RAT'S TRANSPLANTED HEARTS WITH INDIUM-111 LABELED LYMPHOCYTE : THE 54th ANNUAL SCIENTIFIC MEETING OF THE JAPANESE CIRCULATION SOCIETY
- TO PROVE THE EFFICACY OF PHARMACOLOGICAL DENERVATION IN THE CANINE HEART WITH DOUBLE HEART MODEL : PROCEEDINGS OF THE 47th ANNUAL SCIENTIFIC MEETING OF THE JAPANESE CIRCULATION SOCIETY : Electrophysiology (I)
- Strategies for Survival in Non-lschemic Cardiomyopathy Patients with Ventricular Arrhythmias
- Acute Aortic Dissection in a Patient With Idiopathic Dilated Cardiomyopathy
- THE EFFECTS OF DIGITALIS ON AUTOMATICITY AND CONDUCTIVITY IN THE SICK SINUS SYNDROME : IIIrd Auditorium
- The Effect of Self-efficacy on Quality of Life and Psychological Stress Responses in Heart Failure Patients
- The Status of Lipid Management in 1,836 Patients with Coronary Artery Disease : A multicenter survey to evaluate the percentage of Japanese coronary artery disease patients achieving the target low-density lipoprotein cholesterol level specified by the Ja
- CLINICAL SIGNIFICANCE OF ANTITACHYCARDIA PACING THERAPY IN PATIENTS WITH A THIRD-GENERATION IMPLANTABLE CARDIOVERTER-DEFIBRILLATOR
- CARDIAC ELECTRICAL SUPPRESSION DUE TO YOUNG'S SOLUSION AND ITS RECOVERY DURING REPERFUSION IN CANINE DENERVATED HEART : Valvular Heart Disease, Extracorporeal Circulation : III : 48 Annual Scientific Meeting, Japanese Circulation Society
- EXPERIMENTAL STUDY ON PERI AV-NODAL AUTOMATICITY AFTER ATRIOVENTRICULAR INTERRUPTION (AV INTERRUPTION) IN CANINE DENERVATED HEART : PROCEEDINGS OF THE 47th ANNUAL SCIENTIFIC MEETING OF THE JAPANESE CIRCULATION SOCIETY : Electrophysiology (I)
- PHARMACOLOGICAL STUDY AFTER EXPERIMENTAL ATRIOVENTRICULAR INTERRUPTION : Arrhythmia : 46th Annual Scientific Meeting, Japanese Circulation Society
- Angiographic Evidence of Left Main Trunk Spasm as a Possible Cause of Syndrome X