Antibody persistence and immune memory in adults, 15 years after a three-dose schedule of a combined hepatitis A and B vaccine.

A combined hepatitis A and B vaccine is available since 1996. Two separate open-label primary studies evaluated the immunogenicity and safety of this hepatitis A and B vaccine (720 EI.U of HAV and 20 µg of HBsAg) in 306 healthy subjects aged 17-43 years who received three doses of the vaccine following a 0, 1, and 6 months schedule. These subjects were followed up annually for the next 15 years to evaluate long-term persistence of anti-HAV and anti-HBs antibodies. The subjects whose antibody concentrations fell below the cut-offs between Year 11 and Year 15 (anti-HAV: <15 mIU/ml; anti-HBs: <10 mIU/ml) were offered an additional dose of the appropriate monovalent hepatitis A and/or B vaccine. In subjects who received the additional vaccine dose, a blood sample was collected 1 month after vaccination. At the Year 15 time point, all subjects in Study A and Study B were seropositive for anti-HAV antibodies and 89.3% and 92.9% of subjects in the respective studies had anti-HBs antibody concentrations ≥10 mIU/ml. Four subjects (two in each study) received an additional dose of monovalent hepatitis B vaccine and mounted anamnestic responses to vaccination. No vaccine-related serious adverse events were reported. This study confirms the long-term immunogenicity of the three-dose regimen of the combined hepatitis A and B vaccine, as eliciting long-term persistence of antibodies and immune memory against hepatitis A and B for up to at least 15 years after a primary vaccination.

Molecular cloning of a ferret angiotensin II AT(1) receptor reveals the importance of position 163 for Losartan binding.

A complementary DNA for the angiotensin II (AngII) type 1 (AT(1)) receptor from Mustela putorius furo (ferret) was isolated from a ferret atria cDNA library. The cDNA encodes a protein (fAT(1)) of 359 amino acids having high homologies (93-99%) to other mammalian AT(1) receptor counterparts. When fAT(1) was expressed in COS-7 cells and photoaffinity labeled with the photoactive analogue (125)I-¿Sar(1), Bpa(8)AngII, a protein of 100 kDa was detected by autoradiography. The formation of this complex was specific since it was abolished in the presence of the AT(1) non-peptidic antagonist L-158,809. Functional analysis indicated that the fAT(1) receptor efficiently coupled to phospholipase C as demonstrated by an increase in inositol phosphate production following stimulation with AngII. Binding studies revealed that the fAT(1) receptor had a high affinity for the peptide antagonist ¿Sar(1), Ile(8)AngII (K(d) of 5. 8+/-1.4 nM) but a low affinity for the AT(1) selective non-peptidic antagonist DuP 753 (K(d) of 91+/-15.6 nM). Interestingly, when we substituted Thr(163) with an Ala residue, which occupies this position in many mammalian AT(1) receptors, we restored the high affinity of this receptor for Dup 753 (11.7+/-5.13 nM). These results suggest that position 163 of the AT(1) receptor does not contribute to the overall binding of peptidic ligands but that certain non-peptidic antagonists such as Dup 753 are clearly dependent on this position for efficient binding.

Lipoprotein abnormalities associated with cholesteryl ester transfer activity in cystic fibrosis patients: the role of essential fatty acid deficiency.

The purpose of this study was to elucidate the roles of lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP) in the lipoprotein derangement of cystic fibrosis (CF) patients with respect to their essential fatty acid (EFA) status. Triglyceride enrichment and cholesteryl ester (CE) depletion were observed in the lipoproteins of 22 CF patients. The abnormal chemical composition was more severe in 12 EFA-deficient (EFAD) than in 10 EFA-sufficient (EFAS) patients. Expressed in nmol.L-1.h-1, LCAT activity was higher (P < 0.05) in both EFAS (mean +/- SE, 92.7 +/- 1.9) and EFAD (108.8 +/- 3.0) patients than in control subjects (65.2 +/- 0.9). An equal CE transfer was recorded in the lipoprotein-deficient serum, as a source of CETP activity, in all groups studied by using normal exogenous low-density lipoprotein (LDL) and high-density lipoprotein (HDL). However, in contrast to the maximal amount of CE transferred from endogenous HDL to endogenous apolipoprotein B (apo B) in control subjects, a reduction in CETP activity was seen in CF patients and more pronounced in the EFAD group. These findings indicate that impaired lipoprotein composition may have marked effects on the transfer of CE between HDL and apo B in EFAD CF patients.

Effects of radiofrequency catheter ablation on patients with permanent pacemakers.

The objective of this study was to assess the effects of radiofrequency energy application on implanted pacemaker functions. Radiofrequency (RF) catheter ablation may cause pacemaker dysfunction due to electromagnetic interferences. The effects of RF on pacemaker behavior were studied in a series of 38 pacemakers, implanted 18 +/- 26 months prior to a RF procedure using either a right ventricular approach (AV node ablation, n = 35) or a left ventricular approach (left concealed accessory pathway ablation, n = 1; VT ablation, n = 2). The 38 patients (mean age 65 +/- 9 years) included 20 men and 18 women. Before energy applications, the 23 different pacemaker models were programmed to the VVI mode at the lowest available rate. The continuous surface ECG was recorded throughout the procedure. Thorough testing of the devices was performed before and after each RF delivery. Unusual pacemaker responses occurred in 20 of the 38 cases studied (53%). The impact of RF delivery was unpredictable, and variable dysfunctions were observed at different times for a given patient or could vary for a given model. Unusual pacemaker responses included pacemaker inhibition (n = 8), untoggled backup mode (n = 3), electromagnetic interference noise mode (n = 3), temporary RF-induced pacemaker tachycardia (n = 2), erratic behavior (n = 1), oversensing of RF onset and offset (n = 8), and transient loss of ventricular capture, (n = 1). Postablation, most devices automatically toggled back to full functionality. The three devices in the untoggled backup mode had to be reprogrammed to obtain normal operations. At the end of the procedure, pacing thresholds remained unchanged in all but one patient, in whom the increase in ventricular threshold was due to a nicked lead. In conclusion, implanted pacemakers frequently exhibit transient, unpredictable responses to RF energy application. Although all pacemaker functions were restored postablation, some devices had to be reset manually. The anomalies observed during the RF application argue for the simultaneous use of an external pacemaker in pacing-dependent patients.

Etiology and prevention of pulmonary complications following beta-mimetic mediated tocolysis.

OBJECTIVES: This study documents biological (haematocrit variations) and therapeutic parameters (salbutamol doses, volumes perfused) in two groups tocolysed with salbutamol, one with and the other without APO in order to define the risk factors linked to APO and to establish a standard protocol of management. STUDY DESIGN: This retrospective study includes data from 68 intravenous salbutamol tocolysis with four resulting APOs, carried out between January 1st, 1993 and December 31st, 1995. RESULTS: There was an excessive level of salbutamol administered over 48 h in the complicated APO-group (122.5+/-52 mg) opposed to the non-APO group (44.9 21 mg) as well as an overload of perfused solute (3.1+/-1.11) versus (1.9+/-1.11). Blood hemodilution was demonstrated in the APO group with a decrease of haematocrit by over 10% between the admission and the control value. No other risk factor was found. CONCLUSION: Tocolysis should be administered at the lowest possible perfusion rate with incremental doses as long as the heart rate stays under 120 beats/min and stopped after 48 h. Administration of maximal 11 of solute perfused/day is recommended. For the patient's follow-up we estimate daily input and output fluid to avoid hydric overload, and a daily control of haematocrit whose variation must be less than 10%.

[Paradoxal lowering of parasympathetic indices in myasthenic patients]. / Diminution paradoxale des paramètres parasympathiques chez les patients myasthéniques.

Myasthenia gravis is an autoimmune disease presenting antibodies developed against the nicotinic receptors of acetylcholine. The aim of this study was to evaluate heart rate variability in these patients. Heart rate variability was studied with 24 hour Holter recordings. Eighteen myasthenic patients, 7 men and 11 women, under pyridostigmine treatment, with an average age of 40 years (25 to 63 years) were aged and gender matched to a control group of 18 healthy subjects. All patients exhibited normal cardiac status and Doppler echocardiography. The following parameters were collected over 24 hours and the data further differentiated between night and day: for the temporal domain: heart rate, SDNN, pNN50, rMSSD; and for the spectral domain: total power, high frequency (HF) and low frequency (LF) power. The mean heart rate was slightly higher in the myasthenic group (non significant), due to a less marked nocturnal bradycardia. There was a decrease in the observed absolute values of SDNN as well as temporal and spectral parasympathetic indices (pNN50, rMSSD, HF) (p < 0.01) over the 24 hour period. The results were more significant during the night. Cardiac parasympathetic modulation is significantly modified in myasthenic patients. Considering that lack of bradycardia argues against an over active vagal tone, three hypothesis are discussed that favor of a low vagal tone: antibodies effects on the nicotinic receptors of the autonomic nervous system, respiratory impairment and a desensitization of the acetylcholine receptors.

Justifying an obstetrics early discharge program.

A clinical conclusion from a research article, applied hypothetically to a nursing administration problem, demonstrates the importance of applying research to practice and sharing the results with the profession at large. This proposal identifies a needed service, its market and the means to implement the service--developing an early discharge program for mothers and their newborns.

[I am a flying psychiatrist.]. / Je suis un psychiatre volant.

This article deals with the personal experience of the author as a travelling psychiatrist from Montreal into the north west territory of Province of Quebec. The first part presents a day's work under these circumstances. Than follows a brief historical review of what has been accomplish in Quebec and more particularly in the north west area concerning the development of psychiatric services. The travelling type of practice is then related to some trends and theories in community psychiatry. Next, I have tried to explore the internal motivation of the psychiatrist as well as of those who expect his visit. Finally, drawing from this experience as well as from other similar experiences, I try to set down some guidelines that should be helpful in organizing psychiatry on a more permanent basis and in integrating better the efforts of travelling and permanent psychiatrists in remote areas.

Measurement of numicro and nue events in an off-axis horn-focused neutrino beam.

We report the first observation of off-axis neutrino interactions in the MiniBooNE detector from the NuMI beam line at Fermilab. The MiniBooNE detector is located 745 m from the NuMI production target, at 110 mrad angle (6.3 degrees) with respect to the NuMI beam axis. Samples of charged-current quasielastic numicro and nue interactions are analyzed and found to be in agreement with expectation. This provides a direct verification of the expected pion and kaon contributions to the neutrino flux and validates the modeling of the NuMI off-axis beam.

Safe and effective placement of two bipolar silicone leads in the cephalic vein using a hydrophilic guidewire and a split introducer.

The cephalic vein (CV) is preferable to the subclavian vein for implanting permanent pacing leads because of fewer complications. Unfortunately, this access is unusable in a substantial number of patients. This prospective study evaluates a technique to increase CV access for the placement of two silicone bipolar leads used in DDD pulse generator implants. A standard cephalic cutdown was performed under local anesthesia and a hydrophilic guidewire (HGW) threaded in the CV. The first (ventricular) bipolar lead was then introduced and positioned. When possible, introduction of the second (atrial) lead followed the same direct access. A failed introduction led to a modified procedure (MP) relying on a "split" introducer (8-9 Fr Plastimed) advanced with a circular motion over the HGW, then removal of the dilator, removal of the HGW, insertion of the pacing lead into the sheath with placement in the right atrium, followed by sheath withdrawal. Over an 18-month period, 90 consecutive patients had DDD pacemakers implanted. The CV was accessible in 76 (84.5%) of 90 patients and the direct introduction of the ventricular lead was obtained in 74 (97.4%) of these. Atrialization proceeded as follows: direct access CV in 14 (18%) of 76 patients, MP access in 54 (71%) of 76 patients, and MP failure in 8 (11%) of 76 patients. Overall, this approach allowed cephalic dual insertion in 68 (89%) of 76 patients. In conclusion, the modified procedure presented in this study allows a dual catheterization with bipolar leads in 89% of patients when a CV is available. This significantly improves the success rate for dual bipolar lead implants in this configuration.

Tilt table testing of young adult patients: improved speed and sensitivity using an isoproterenol bolus and a continuous 60 degrees tilt.

The tilt table is a diagnostic device used to induce vagal syncope and determine etiology. Sensitivity enhancing techniques, such as the administration of isoproterenol, can be applied to children and young adults to compensate for the otherwise low sensitivity (20%-30%) observed in that population. This study describes an improved test that offers a simplified approach while decreasing the amount of time involved by up to 50%, without compromising sensitivity. This 45-minute procedure relies on sensitization with isoproterenol administered as a 2- to 80 micrograms bolus instead of a continuous infusion. The isoproterenol is injected at the 30th minute of a 45-minute 60 degrees tilt test without returning the patient to the supine position. In this study, the isoproterenol bolus tilt test was found to be "positive" in 24 of 30 patients reporting unexplained syncope: 10 cases before the 30th minute (11.2 +/- 8.4 min) and 14 cases after administration of 5.1 +/- 1.9 micrograms of isoproterenol.

Combined (n-3 and n-6) essential fatty deficiency is a potent modulator of plasma lipids, lipoprotein composition, and lipolytic enzymes.

Essential fatty acids (EFA) are important structural and functional components of cell membranes. Their deficiency has been associated with several clinical and biochemical abnormalities. In the present study, the lipid profile as well as the concentration, composition, and metabolism of lipoproteins were examined in rats rendered EFA-deficient over a period of 12 weeks. Changes in plasma fatty acids mainly induced an increase of palmitoleic (16:1 n-7) and eicosatrienoic (20:3 n-9) acids, while linoleic (18:2 n-6), arachidonic (20:4 n-6), linolenic (18:3 n-3), and docosahexaenoic (22:6 n-3) acids were decreased. The results show increased concentrations of free fatty acids (FFA) (P less than 0.001), triglycerides (P less than 0.001), total cholesterol (P less than 0.02), free cholesterol (P less than 0.005), and phospholipids (P less than 0.05) when compared to pair-fed controls. Similar levels of cholesteryl esters were found in the two groups, and lecithin: cholesterol acyltransferase activity (nmol/100 microliters plasma per h) (8.98 +/- 1.44 vs 8.72 +/- 0.50) did not differ. On the other hand, postheparin extrahepatic lipoprotein lipase (LPL) activity was significantly (P less than 0.002) decreased (5.96 +/- 0.29 vs 7.29 +/- 0.68 mumol FFA/ml per h) and could account for the hypertriglyceridemia as well for the relative triglyceride enrichment of very low density lipoprotein, intermediate density lipoprotein, and low density lipoprotein particles. This enzymatic depletion of LPL was mainly due to the adipose tissue, since a higher level (P less than 0.001) of hepatic lipase (325.8 +/- 16.0 vs 130.8 +/- 9.5 nmol FFA/mg protein per h) was found in liver acetone powder extracts.(ABSTRACT TRUNCATED AT 250 WORDS)

Factors associated with early atrial fibrillation after ablation of common atrial flutter. A single centre prospective study.

BACKGROUND: The occurrence of early atrial fibrillation (< or = 6 months) after ablation of common atrial flutter is of clinical significance. Variables predicting this evolution in ablated patients without a previous atrial fibrillation history have not been fully investigated. OBJECTIVES: The aim of the present study was: (1) to identify predictive factors of early atrial fibrillation (< or = 6 months) in the overall population following atrial flutter catheter ablation; (2) to identify predictive variables of early atrial fibrillation following (< or = 6 months) atrial flutter catheter ablation within a subgroup of patients without documented prior atrial fibrillation. METHODS: This study prospectively included 96 consecutive patients (age 65 +/- 13 years; 18 women) over a 12-month period. Their counterclockwise flutter was ablated by radiofrequency, by the same operator, with an 8-mm-tip catheter. Clinical, electrophysiological and echocardiographic data were collected and 27 variables were retained for analysis: age; gender; type of atrial flutter (permanent vs paroxysmal); symptom duration (months +/- SD); pre-ablation history of atrial fibrillation; structural heart disease; left ventricular ejection fraction (%); left atrial size (mm); cava--tricuspid isthmus dimension; septal isthmus dimension; systolic pulmonary pressure > or < or = 30 mmHg; right atrial area; left atrial area; isthmus block; number of radiofrequency applications (+/- SD); antiarrhythmic drugs at discharge; left ventricular diastolic diameter; left ventricular systolic diameter; left ventricular telediastolic volume; left ventricular telesystolic volume; A-wave velocity (cm . s(-1)); E-wave velocity (cm . s(-1)); E/A; isovolumetric relaxation time; E-wave deceleration time; significant mitral regurgitation and flutter cycle length (ms). RESULTS: Of the 96 consecutive ablated patients, early atrial fibrillation was documented in 16 patients (17%). Atrial fibrillation occurred 30 +/- 46 days (range 1 to 171 days) after ablation. Univariate analysis associated an early occurrence of atrial fibrillation with: atrial fibrillation history, left ventricular ejection fraction, left atrial size, left ventricular telesystolic volume, A-wave velocity, significant mitral regurgitation and flutter cycle length. Multivariate analysis using a Cox model found that the only independent predictors of early atrial fibrillation were left ventricular ejection fraction and pre-ablation history of atrial fibrillation. In the subgroup without prior atrial fibrillation history (n=63; 66%), the only independent predictor of early atrial fibrillation was the presence of a significant mitral regurgitation. CONCLUSIONS: In a subgroup of patients without atrial fibrillation history, 8% of patients revealed an early atrial fibrillation. Mitral regurgitation is a strong predictive factor of early atrial fibrillation occurrence with 80% sensitivity, 78% specificity and 98% negative predictive value. These data should be considered in post-ablation management.

Predictive factors of ventricular fibrillation triggered by pause-dependent torsades de pointes associated with acquired long QT interval: role of QT dispersion and left ventricular function.

INTRODUCTION: Death due to acquired torsades de pointes usually is caused by ventricular fibrillation (VF), but the contributing factors to VF triggered by pause-dependent torsades de pointes are not understood. METHODS AND RESULTS: We evaluated 91 patients who fulfilled four criteria: (1) pause-dependent torsades de pointes; (2) prolonged QT interval and/or corrected QT (QTc) (>0.44 sec); (3) long-short initiation sequence; and (4) conditions known to induce pause-dependent torsades de pointes. There were 38 patients with a documented VF (group I) and 53 without VF (group II). Absolute and relative dispersions of QT and QTc were calculated based on the 12-lead standard ECG. Group I differed from group II with regard to myocardial infarction history (32% vs 13%; P = 0.035), left ventricular ejection fraction (44% +/- 14% vs 65% +/- 9%; P < 0.0001), presence of structural heart disease (100% vs 20.8%; P < 0.0001), QT mean (591 +/- 73 msec vs 514 +/- 78 msec; P < 0.0001), QTc mean (563 +/- 76 msec vs 508 +/- 90 msec; P = 0.002), absolute QT dispersion (166 +/- 56 msec vs 84 +/- 49 msec; P < 0.0001), relative QT dispersion (9.9% +/- 3.5% vs 6.3% +/- 3.2%; P < 0.0001), absolute QTc dispersion (158 +/- 57 msec vs 81 +/- 44 msec; P < 0.0001), and relative QTc dispersion (9.9% +/- 3.6% vs 6.2% +/- 3%; P < 0.0001). Multiple regression analysis showed that ejection fraction (P = 0.0001), presence of structural heart disease (P < 0.0001), and relative QTc dispersion (P = 0.038) were the only independent predictors of VF. CONCLUSION: Left ventricular function, presence of structural heart disease, and QTc relative dispersion should be evaluated carefully in patients with conditions susceptible to inducing torsades de pointes.

Optimizing the hemodynamic performance of the DDD pacemaker: impact of the atrioventricular delay on the pulmonary venous flow pattern.

UNLABELLED: This study evaluated the impact of the atrioventricular delay (AVD) on the pulmonary venous flow pattern (PVFP). METHODS: Transthoracic Doppler PVFP were obtained during atrial and ventricular pacing at a fixed rate of 70 beats/min in 20 patients equipped with a DDD pacemaker, diastolic dysfunction linked to an impaired relaxation, a mean ejection fraction of 49%, and AV block. Two subgroups were analyzed equally: group I: seven patients with a normal ejection fraction and group II: 13 patients with decreased ejection fraction. Three different AVDs were studied: short (50 ms), intermediate (150 ms), and long (250 ms). RESULTS: As the AVD increased, the diastolic filling time and the peak atrial reverse flow wave decreased (P < 0.001). There was a decreasing D wave and no significant change in the peak velocity of the S wave. The S wave became biphasic in all patients at the longest AVD of 250 ms. The systolic (S) velocity time integral (VTI) of the pulmonary wave and the systolic/total PVF-VTI ratio increased significantly (P < 0.001). A similar response was seen in both group of patients. CONCLUSIONS: These data correlated the AVD with PVFP, supplying critical systolic information completing the diastolic data obtained from mitral Doppler patterns. These systolic measurements were especially useful for patients with heart failure and a DDD pacemaker, in order to obtain the longest diastolic filling time at the lowest atrial pressure.

Cavotricuspid isthmus mapping to assess bidirectional block during common atrial flutter radiofrequency ablation.

BACKGROUND: We sought to compare published methods to an alternative approach ascertaining cavotricuspid isthmus (CTI) block during atrial flutter ablation. METHODS AND RESULTS: In 39 consecutive patients who underwent an atrial flutter ablation procedure, a 24-pole mapping catheter was positioned so that 2 adjacent dipoles were bracketing the targeted CTI line of block (LOB), with proximal dipoles lateral to the LOB and distal dipoles in the coronary sinus. Two pacing sites were lateral (positions A and B) and 2 were septal (positions C and D) to the LOB, with locations A and D closest to the LOB. A resulting CTI block was accepted when 3 criteria were fulfilled: (1) complete reversal of the right atrial depolarization on the 24-pole catheter when pacing in the coronary sinus, (2) conduction delays from A to D greater than from B to D, and (3) conduction delays from D to A greater than from C to A. A successful CTI block was obtained in all patients. Before CTI block was obtained, a progressive CTI conduction delay was observed in 11 patients (28.2%). During the procedure, the 3 criteria defined above were either all present or all absent. CONCLUSIONS: This study establishes that reversal of the atrial depolarization sequence up to the LOB is a definitive and mandatory criteria of successful atrial flutter ablation.

Accuracy and limitations of published algorithms using the twelve-lead electrocardiogram to localize overt atrioventricular accessory pathways.

INTRODUCTION: The purpose of this study was to evaluate the accuracy and limitations of published algorithms using the 12-lead ECG to localize AV accessory pathways (APs). METHODS AND RESULTS: The 11 relevant algorithms found in the literature (MEDLINE database and major scientific sessions) were tested on a series of 266 consecutive patients who successfully underwent radiofrequency catheter ablation of a single overt AV AP. The positive predictive values (PPV) of the algorithms in applicable patients were significantly lower for algorithms with > 6 accessory location sites (40.6% +/- 10.9% vs 61.2% +/- 8.0%; P < 0.03) and show a tendency for algorithms not relying on delta wave polarity but on QRS polarity only (36.6% +/- 11.2% vs 52.3% +/- 13.1%; P = 0.09). The PPV in applicable patients is related to the AP location (P < 0.001) and ranked from the highest to the lowest as follows: left lateral (mean PPV = 86.3%), posteroseptal (mean PPV = 65.2%), right anteroseptal (mean PPV = 45.2%), and right posterolateral (mean PPV = 23.4%). CONCLUSION: Our study suggests that the accuracy of algorithms relying on the 12-lead ECG depends on AP locations as defined in the algorithms and on the number of AP sites. The accuracy tends to be lower when delta wave polarity is not included in the algorithm's architecture. This should be considered when using these algorithms or when building new ones.

Correlation between electrogram morphology and standard criteria to validate bidirectional cavotricuspid block in common atrial flutter ablation.

AIM: Assessment of a bidirectional conduction block within the cavotricuspid isthmus (CTI) is critical during radiofrequency (RF) atrial flutter (AF) ablation. We investigated the use of bipolar atrial electrogram (BAE) morphology as an additional criterion identifying CTI block and tested it against two recognized criteria: differential pacing and reversal of the right atrial depolarization sequence during coronary sinus (CS) pacing. METHODS AND RESULTS: An RF ablation procedure was performed during 600 ms CS pacing in 100 consecutive patients with a common AF. BAE recorded along the CTI were continuously monitored. CTI conduction block was achieved by RF ablation in all patients and a clear change in BAE polarity in the Electrogram recorded by the dipoles located on the CTI and immediately lateral to the intended line of block (RS to QR pattern) associated with a confirmed CTI conduction block was observed in all cases. BAE morphology changes predicted bidirectional CTI conduction blocks with a 100% positive and a 100% negative predictive value. At a mean follow-up of 33 +/- 11 months, there was a 5% AF recurrence rate. CONCLUSIONS: Our study suggests that morphological changes in BAE recorded at sites lateral and adjacent to the target line of block may be used as a unique and robust criterion to validate CTI conduction block during AF ablation procedure.