Objectives of our research are: Cardiac electrophysiological properties of paroxysmal atrial fibrillation patients. Evaluation of short-term outcomes of radio frequency ablation of paroxysmal atrial fibrillation.
MINISTRY MINISTRY OF EDUCATION AND TRANING OF NATIONAL DEFENCE MILITARY MEDICAL UNIVERSITY PHAM TRAN LINH STUDY ON ELECTROPHYSIOLOGICAL PROPERTIES AND THE EFFICACY OF CATHETER – BASED RADIO FREQUENCY ABLATION OF PAROXYSMAL ATRIAL FIBRILLATION Speciality: Medical Cardiology Code: 62720141 ABSTRACT OF MEDICAL PHD THESIS HA NOI – 2016 Training institution: MILITARY MEDICAL UNIVERSITY Instructors: 1. NGUYEN LAN VIET, MD.PHD.Prof 2. PHAM QUOC KHANH, MD.PHD The 1st opponent: Doan Van De, MD.PHD.Prof The 2nd opponent: Do Doan Loi, MD.PHD.Prof. The 3rd opponent: Tran Van Riep, MD.PHD.Prof This thesis will be presented at the commission for theses of Military Medical University At hours of day month year This thesis may be found at: 1. The National Library 2. The Library of Military Medical University 3. The Library of Bach mai General Hospital LIST OF PUBLISHED SCIENTIFIC WORKS RELATED TO THE THESIS 1. Pham Tran Linh, Pham Quoc Khanh, Nguyen Lan Viet (2015), "Initial evaluation of the effectiveness of catheter – based radio frequency ablation of paroxysmal atrial fibrillation", journal of Vietnamese Medical, 429 (2), pp. 144 150 2. Pham Tran Linh, Pham Quoc Khanh, Nguyen Lan Viet (2015), "Clinical manifestations and electrophysiologic features in patients with paroxysmal atrial fibrillation", journal of Vietnamese Medical, 430 (1), pp. 159 165 INTRODUCTION Atrial fibrillation (AF) is one of the most common types of arrhythmia. AF is associated with a wide range of complications in clinical practice and may contribute to 5% of stroke cases a year. Mortality may increase to 34% in patients with heart failure if AF is concomitant. It is known that AF increases in the prevalence with advancing age. The incidence of AF is approximately 0.1% in the patients under 40 years of age while it approaches 1.5 – 2% in the group over 60 years of age. It was the first time in 1994 when Haissaguerre utilized the radio frequency (RF) energy as a therapy for AF patients. Nevertheless, this method had limitations such as low successful rate of 33 – 60%, high rate of complications, long procedure time (5 – 6 hours) In 1996, Pappone used a three dimensional mapping system named CARTO to facilitate the therapy of AF with RF energy CARTO system has brought higher efficacy in the treatment of AF as it guarantees high successful rate and low complication rate The system has been upgrading so far to vast the utility in RF ablation of AF as the most advanced curing method for the disease. Back to 1998 when RF energy was first settled in Vietnam Heart Institute – Bach Mai Hospital, then was widespreaded to other heart centers up and down the country, launching the initiation for the interventional rhythmology in Vietnam However, paroxysmal AF has not been treated with RF energy as a routine procedure in Vietnam. Some questions have been raised to require the answers. What are the electrophysiological properties of the paroxysmal AF in Vietnamese patients ? What are the posibilities to utilize the therapy and its limitations ? What are the optimal indications for Vietnamese patients ? What are the early outcomes and the followup results ? In contributing to bring this method into routine practice in Vietnam, we conduct a research named “Electrophysiological properties and the efficacy of catheter – based radio frequency ablation of paroxysmal atrial fibrillation” Objectives of our research are: Cardiac electrophysiological properties of paroxysmal atrial fibrillation patients. Evaluation of shortterm outcomes of radio frequency ablation of paroxysmal atrial fibrillation. * Contributions of the research: Paroxysmal atrial fibrillation often originates from the four pulmonary veins with 83.3% were from left pulmonary veins and rarely comes from right atrium. In episodes of atrial fibrillation, the average AA intervals were 196.8 ms and VV intervals were 574.4 ms. Radio frequency ablation of paroxysmal atrial fibrillation has a high successful rate. Sinus maintenance rate was reached at 88.1% just after procedures and 74.3% after 12 months of followup. Recurrence rate was 11.4% and complication rate was 4.7% with no death. * Structure of the thesis: The thesis consists of 136 pages (not including appendix and list of references), 50 tables, 10 graphs and 33 figures There are 132 reference documents, including 12 in Vietnamese and 120 in English. There are 3 pages for the part of Introduction, 36 pages for Overview, 21 pages for Object and Methodology, 33 pages for Research Result, 39 pages for Discussion, 3 pages for Conclusion, 1 page for Suggestion. CHAPTER 1 OVERVIEW 1.1 ELECTROPHYSIOLOGICAL PROPERTIES OF THE LEFT ATRIUM ANATOMY AND CARDIAC CONDUCTION SYSTEM 1.1.1 Left atrium anatomy: left atrium is bordered by the pulmonary venoatrial junctions, atrioventricular junction at the mitral orifice, the left appendage and the septal part. Left atrium’s walls and atrial septum: left atrium’s walls include anterior wall, superior wall, free wall (lateral wall), posterior wall and septal wall Atrial muscle: the left atrium consists of three layers: epicardium, atrial muscle and endocardium. The atrial musculature is constructed by circumferential and longitudinal muscular bundles. Those bundles contribute to the formation of pectinate muscles of the atrium. Pulmonary veins and ostia: all four pulmonary veins enter the left atrium at the posterior wall. In most of cases, those pulmonary veins are separated. 1.1.2. Conduction system: Sinus node, internodal pathways, atrioventricular node, His bundle and branches, Purkinje fibers. 1.2. ELECTROPHYSIOLOGICAL PROPERTIES AND CONDUCTION SYSTEM Including activation potential, excitability, automaticity, conductivity and refractoriness. 1.3. PATHOPHYSIOLOGY IN ATRIAL FIBRILLATION 1.3.1. Electrophysiological mechanisms: 3 mechanisms for AF has been explained: Single micro reentrant stable circuits Frequently macro reentrant unstable circuits. Single automatic focus firing short interval impulses. 1.3.2 Hemodynamic Consequences: hemodynamic consequences of AF result from multi factors such as loss of atrial contraction, irregular ventricular response, rapid ventricular rate, coronary hypoperfusion. 1.3.3. Mechanisms of thrombosis in AF: Pathophysiology of thrombosis in patients with AF is complicated Virchow’s triad contributes factors in leading to thrombosis: blood stasis, alteration of vessels’ intimal function and blood hypercoagulability. 1.4. DIAGNOSIS OF ATRIAL FIBRILLATION 1.4.1. Classification of AF based on clinical settings: Paroxysmal AF: AF that terminates spontaneously or with intervention within 7 days of onset, commonly within 48 hours. Persistent AF: AF that sustains over 7 days from onset and be terminated by pharmacological or directcurrent cardioversion. Permanent AF: is persistent AF that can not terminate by pharmacological or directcurrent cardioversion. 1.4.2 Etiology: valvular heart diseases (mitral stenosis or mitral regurgitation), coronary artery diseases, left ventricular dysfunction, hypertension, left ventricular hypertrophy, congenital heart diseases including atrial septal defect, transposition of great vessels …; hyperthyroidism, idiopathic AF … 1.4.3. Diagnosis: diagnosis of AF bases on routine electrocardiograms. Some investigations can be doned to diagnose the etiology of AF including thyroid hormones, echocardiography, chest Xray, stress test, 24 hour ECG monitoring, event recorder, electrophysiological study 1.4.4 Principles of treatment: rhythm control and thrombosis prevention Based on the classification of AF, medications, interventional procedures or other methods can be chosen. 11 Couplet PACs 203.1 ± 684.4 0 – 3.850 Triplet PACs 32.7 ± 64.7 0 – 288 Atrial Tachycardia 10.4 ± 399.3 0 – 258 3.2 ELECTROPHYSIOLOGICAL CHARACTERISTICS IN PATENTS WITH PAROXYSMAL AF 3.2.1. At baseline with sinus rhythm 3.2.1.1. Basic intervals Table 3.5. Basic intervals ≤ 60 y > 60 y (n=25) (n=17) Basic cycle length (ms) 760.2±188 PA intervals (ms) Index P Overall 886.7±113 0.021 810.8 ± 172.9 21.0 ± 5.1 23.9 ± 5.2 0.124 26.7 ± 8.6 AH intervals (ms) 91.7 ± 18.3 88.1 ± 12.3 0.092 90.5 ± 15.9 His duration (ms) 19.0 ± 6.9 18.1 ± 2.9 0.488 18.7 ± 5.6 HV intervals (ms) 47.4 ± 5.7 48.1 ± 3.9 0.618 47.7 ± 5.0 91.3 ± 11.9 91.2 ± 13.4 0.975 91.3 ± 12.4 389.3 ± 42.2 391.4±29.3 0.834 390.2 ± 30.7 QRS duration (ms) QT intervals (ms) 42 patients were divided into 2 groups based on age. A group consisted patients ≤ 60 years of age and the other one consisting 12 patients > 60 years of age. The basic cycle length of patients ≤ 60 years of age were significantly shorter than those of > 60 years of age There was no significant difference between the measurements of other intervals. 3.2.1.2. Electrophysiological study of sinus node function Table 3.6. Sinus node recovery time (SNRT)and corrected sinus node recovery time (cSNRT) based on age and gender Index Male (n=36) Gender Female (n=6) ≤ 60 (n=25) Age > 60 (n=17) Overall (n=42) SNRT (ms) 1181.8 ± 201.0 1120.7 ± 170.6 1140.6 ± 190.5 1222.0 ± 200.9 1173.9 ± 196.4 p 0.52 0.20 cSNRT (ms) p 310.8 ± 143.2 0.169 403.7 ± 89.2 319.8 ± 114.1 0.881 326.8 ± 174.9 322.7 ± 140.1 There was no significant difference in the SNRT between the male and female group (p > 0.05) No significant difference was found between the cSNRT of the patients > 60 years of age and the patients ≤ 60 years of age 3.2.1.3 Effective refractory periods (ERP) of the atrium and ventricle Table 3.7. ERP of the atrium and ventricle Index Atrial ERP (ms) Ventricular ERP (ms) Atrio ventricular dissociation point (ms) ≤ 60 y (n=25)1 198.7 ± 19.4 218.7 ± 58.7 395.3 ± 21.0 13 > 60 y (n=17)2 215.6 ± 15.9 222.5 ± 15.3 426.3 ± 73.5 Overall (n=42) 205.6 ± 19.7 220.3 ± 17.2 407.9 ± 66.1 P1,2 0.007 0.505 0.001 The atrial ERP and ventricular ERP were within the normal range. There was no significant difference between two groups of age The atrial ERP of the patients ≤ 60 years of age was significantly shorter than the group of > 60 years of age with p = 0.007. 3.2.2. Electrophysiological characteristics in AF Atrial programmed electrical stimulations were performed to induce AF and then action potentials were recorded at different locations in the left atrium. 3.2.2.1. Locations of PACs triggering episodes of AF Table 3.8. Locations of PACs triggering AF (n=42) Location Number % Superior vena cava 4.8 Inferior vena cava 0 Right atrial isthmus 4.8 Left superior PV 35 83.3 Left inferior PV 30 71.4 Right superior PV 33 78.6 Right inferior PV 31 73.8 Right atrium Left atrium 14 Left appendage 16.7 Left atrial isthmus 4.8 Over 70% of PACs originated from pulmonary veins, whilst up to 83.3% of those were from left superior PA 3.2.2.2. Interval recordings in AF Table 3.9. Interval recordings based on group of age Index Average AA intervals (ms) Shortest AA intervals (ms) Longest AA intervals (ms) Average VV intervals (ms) Shortest VV intervals (ms) Longest VV intervals (ms) ≤ 60 y (n=25) > 60 y (n=17) P Overall (n=42) 201.1 ± 35.7 194.7 ± 41.7 0.629 196.8 ± 39.5 135.6 ± 39.4 123.1 ± 29.9 0.261 127.3 ± 33.4 263.1 ± 51.5 249.8 ± 38.1 0.346 254.2 ± 42.9 543.7±104.4 589.8 ±107.8 0.194 574.4 ±107.6 350.0 ± 88.6 415.3 ±102.2 0.049 393.5 ±101.7 813.8±191.5 827.6 ±205.0 0.834 823.0 ±198.4 The role of AV conduction is important in reducing the impulses travelling from atria to ventricles to maintain tolerant ventricular response 3.3. RESULTS OF PAROXYSMAL ATRIAL FIBRILLATION ABLATION 3.3.1. Results of procedures 3.3.1.1. Procedure time Table 3.10. Procedure time Index Overall (n=42) Procedure time 288.8 ± 60.4 Other PV isolation ablation sites (n=28) (n=14) 293.6 ± 58.9 265.0 ± 68.8 P 0.173 ... properties of paroxysmal? ? atrial? ?fibrillation? ?patients. Evaluation of shortterm outcomes of radio frequency? ? ablation? ?of? ?paroxysmal? ?atrial? ?fibrillation. * Contributions? ?of? ?the? ?research: ... ? ?Electrophysiological properties and the efficacy of catheter – based radio frequency ablation? ?of? ?paroxysmal? ?atrial? ?fibrillation? ?? Objectives? ?of? ?our research are: Cardiac electrophysiological. .. Pham Tran Linh, Pham Quoc Khanh, Nguyen Lan Viet (2015), "Initial evaluation? ?of? ?the? ?effectiveness? ?of? ?catheter? ?–? ?based? ?radio? ? frequency? ?ablation? ?of? ?paroxysmal? ?atrial? ?fibrillation" , journal? ?of Vietnamese? ?Medical, 429 (2), pp. 144 150