Optimal method for ablation of atypical AVNRT

BACKGROUND

Considering that ablation of atypical AVNRT may be unsuccessful after ablation at the right posterior septum, in this study, we aimed to present an optimal method for ablation of atypical AVNRT. Also, we evaluated the efficacy of this technique for preventing recurrences.

METHODS

This is a prospective, double-center study. It was conducted on 62 patients with atypical AVNRT referred for radiofrequency ablation. The patients were randomly divided into two groups before ablation: 1-Group A (n = 30): treated with conventional ablation at the anatomic area of the slow pathway; 2-Group B (n = 32): ablation was done 2 mm higher in the septum during fluoroscopy.

RESULTS

The mean age of patients in groups A and B were 54 ± 11.7 and 55 ± 12.2, respectively (P = 0.43). In group A, ablation was successful in 24 (80%) patients following right-sided slow pathway ablation, and the remaining patients required further treatment with either a left-side approach (N = 4, 13.3%) or ablation of additional regions (N = 2, 6.7%). In group B, ablation was successful in all patients. After a 48-month follow-up, recurrence of symptomatic atypical AVNRT was detected in 4 (13.3%) patients of group A and none of group B patients (p < 0.001).

CONCLUSION

In patients with atypical AVNRT, ablation 2 mm above the conventional area is more promising regarding success rate and recurrence of the arrhythmia.

Signal averaged ECG in patients with early repolarization

BACKGROUND

Early repolarization (ER) pattern is diagnosed when the J-point is elevated on the patient's electrocardiogram. The aim of this study was to evaluate signal-averaged electrocardiography (SAECG) in patients with ER pattern.

METHODS

Subjects were divided into three groups: 1-patients with normal ECG pattern (control group); 2-patients with J-point elevation in the inferior leads; and 3-patients with J-point elevation in non-inferior leads.

RESULTS

The mean filtered QRS duration in groups with J-point elevation in inferior leads and non-inferior leads and in the control, was 86.4 ± 23.4 msec, 84.8 ± 26.6 msec, and 85.8 ± 24.8 msec, respectively, indicating no significant difference across the three groups. The mean duration of terminal QRS < 40µV was 21.2 ± 4.2 msec, 22.8 ± 4.6 msec, and 23.1 ± 4.5 msec in the mentioned groups, respectively, without a significant difference between the groups. Additionally, the mean root-mean-square voltage of terminal 40 msec was 34.5 ± 8.3 µV, 35.3 ± 8.6µV, and 35.7 ± 9.2 µV in patients with increased J-point in inferior leads, non-inferior leads, and the control group, respectively, showing no difference between the groups.

CONCLUSION

In conclusion, we found that parameters in SAECG did not have any significant difference between patients with ER pattern and healthy individuals. Moreover, we concluded that SAECG cannot distinguish the patients with elevated J-point in inferior leads from non-inferior leads. Overall, SAECG does not appear to be a reliable diagnostic tool for the assessment of ER pattern.

Effect of Cardiac Resynchronisation Therapy on Electrical Remodelling

BACKGROUND

Cardiac resynchronisation therapy (CRT) is an accepted device therapy in patients with low ejection fraction. Beneficial effects of CRT result from mechanical remodelling. Some controversial reports suggest that CRT may also induce electrical remodelling with intrinsic QRS narrowing but still the effect of CRT on electrical remodelling is an issue for debate. The aim of our study was to evaluate the effects of CRT on intrinsic QRS duration. For clarity, our analysis was performed by the signal averaged electrocardiogram (SAECG) which is a high resolution electrocardiographic signal suitable for accurate measurement of QRS duration. Signal averaged electrocardiogram provides a better value of QRS duration compared to 12-lead ECG by the ability to detect ventricular late potentials.

METHODS

A total of 48 consecutive patients with severe systolic dysfunction and typical left bundle branch block (LBBB) were enrolled in the study prospectively. Patients were scheduled for CRT-D implantation according to the current guidelines. Intrinsic QRS duration was accurately measured by SAECG before and at least 14 months after CRT implantation.

RESULTS

The mean intrinsic QRS duration remained unchanged during follow-up (from 149.9±13.8ms to 149.6±18.4ms; P= 0.3). Among 32 CRT responder patients, the mean intrinsic QRS duration remained unchanged during follow-up. Also, the mean intrinsic QRS duration showed no significant changes in 16 CRT non-responders.

CONCLUSION

Structural remodelling induced by CRT does not necessarily translate into decrease of intrinsic ventricular activation. Despite significant left ventricular recovery, electrical characteristics of the left ventricular conduction system cannot generally be expected to recuperate.

Genetic analysis of cardiac SCN5A Gene in Iranian patients with hereditary cardiac arrhythmias

Objective:

SCN5A encodes alpha subunit of the major sodium channel (Nav1.5) in human cardiac tissue. Malfunction of this cardiac sodium channel is associated with a variety of cardiac arrhythmias and myocardial inherited diseases.

Methods:

Fifty-three members from three families each diagnosed with long-QT syndrome type 3 (LQTS3), Brugada syndrome (BrS), or sick sinus syndrome (SSS) were included in this observational, cross-sectional study. In this study, we analyzed the sequences of coding region of the SCN5A gene.

Results:

Eleven members of the LQTS family (39%) showed p.Gln1507-Lys1508-Pro1509del mutation, 8 of BrS family (50%) showed p.Arg222Ter nonsense mutation, and 5 of 9 SSS family members (55%) showed a novel p.Met1498Arg mutation in the SCN5A gene.

Conclusion:

p.Gln1507-Lys1508-Pro1509del mutation, p.Arg222Ter nonsense mutation, and p.Met1498Arg in LQTS, BrS, and SSS, respectively, are reported for the first time in the Iranian population. Information regarding underlying genetic defects would be necessary for verifying certain clinically diagnosed arrhythmia types, carrier screening in affected families, and more precise therapy of the patients are required. (Anatol J Cardiol 2016; 16: 170-4)

Idiopathic right atrial enlargement

A 26-year-old man presented with lower extremity edema and abdominal protrusion associated with dyspnea for 5 years, which had increased 7 months earlier. Echocardiography demonstrated a huge right atrium of 19.5 × 15.2 cm with a thick smoke pattern and severe tricuspid regurgitation. Magnetic resonance imaging confirmed intact pericardium. A pulmonary perfusion scan demonstrated multiple perfusion defects, suggesting recurrent small pulmonary emboli. Idiopathic enlargement of the right atrium was diagnosed. The patient declined surgery.

Positive Brugada challenge test in V1 R-V3 R as a predictor of malignant prognosis in Brugada patients

BACKGROUND

The Brugada syndrome is a heterogeneous genetic disease that predisposes to life-threatening ventricular tachyarrhythmias and sudden cardiac death (SCD). The only proven way to prolong the survival of patients with Brugada syndrome is to implant an implantable cardioverter-defibrillator (ICD). This should be implanted for high-risk patients only.

METHOD

The patients with type 2 or 3 Brugada ECG pattern were selected for the study. We evaluated 126 patients with Brugada type ECG patterns. Nineteen patients had positive response. Those who had positive result in right side located leads had poorer prognosis.

CONCLUSION

Positive flecainide challenge test in right side located pericordial leads can be used as a predictor of poor prognosis in Brugada patients. This can be evaluated in another research for its role in the implantation of ICD. Also, the oral flecainide is not sensitive enough to rule out the presence of Brugada syndrome and it should not be trusted as a screening test for suspected cases.

Electrocardiographic, electrophysiologic, and anatomical features of ventricular tachycardia originating from noncoronary cusp

In this article, we report 2 young patients (a 15-year-old adolescent girl and a 25-year-old man) with drug-refractory palpitations. Admission electrocardiograms showed runs of ventricular tachycardia with left bundle-branch block morphology, left inferior axis, early precordial QRS transition, and positive QRS complex in lead I. In right ventricular mapping, the earliest activation site was found in the His bundle region. Aortic root mapping showed a very early fractionated ventricular signal with large atrial potential and no His potential in the noncoronary cusp region. Radiofrequency energy application in this region resulted in tachycardia termination within 5 to 10 seconds. During a 3- to 6-month follow-up period, the patients remained asymptomatic, and the electrocardiogram showed no ventricular arrhythmias.

Clinical and electrocardiographic predictors of positive response to the intravenous sodium channel blockers in patients suspected of the Brugada syndrome

BACKGROUND/OBJECTIVES

Sodium channel blockers are used to unmask the diagnostic ECG pattern of the Brugada syndrome (BrS) in case of a non-diagnostic baseline ECG. The aim of the study was to determine clinical and ECG predictors of a positive challenge test in patients suspected to the BrS.

METHODS

A total of 106 consecutive patients (91 men; mean age, 35 ± 12 years) suspected of the BrS underwent the intravenous sodium channel blocker challenge test with procainamide or flecainide.

RESULTS

Of the 106 patients, positive tests were detected in 20 (19%) patients. During test, a transient episode of a second-degree atrioventricular block and isolated ventricular ectopies were observed in 1 (0.9%) and 2 (1.9%) patients, respectively. A QRS prolongation ≥ 30% was observed in 4 (3.8%) patients. Baseline QRS duration in V1 ≥ 110 ms had a sensitivity of 70% and a specificity of 80% for a positive response. An ST-segment elevation ≥ 0.17 mV in V2 had a sensitivity of 60% and a specificity of 82% for a positive response. Of the multiple clinical and ECG variables entered into a binary logistic regression analysis, a history of syncope (P=0.001), previous cardiac arrest (P=0.001), baseline QRS duration in V1 ≥ 110 ms (P=0.001), and baseline ST-segment elevation in V2 ≥ 0.17 mV (P=0.012) emerged as the independent predictors of a positive response to the intravenous challenge with sodium channel blockers.

CONCLUSION

The results of the sodium channel blocker challenge test can be predicted by clinical presentation and baseline ECG features.

Left atrial volume: a novel predictor of hepatopulmonary syndrome

OBJECTIVES

We studied patients with hepato-pulmonary syndrome (HPS). We found that HPS is frequently present in patients with left atrial enlargement. The aim of this prospective study was to evaluate the possible correlation between left atrial volume and HPS.

METHODS

Adult patients (>18 yr old) with biopsy proven liver cirrhosis who were referred for liver transplantation were enrolled in the study. Diagnosis of HPS was established when the following points were fulfilled: (a) the presence of chronic liver disease, (b) increased alveolar-arterial difference (AaDO(2)), (c) intrapulmonary vascular dilatation, and (d) absence of primary cardiac or pulmonary disease.

RESULTS

We enrolled 41 patients (mean age 47.1 +/- 10.6 yr) diagnosed with HPS. Also 108 Child-Pugh score matched cirrhotic patients (mean age 49.2 +/- 9.3 yr) who have negative contrast echocardiography and normal age-related AaDO(2) were selected as a control group for the purpose of comparison of left atrial volume (LAV). LAV was significantly greater in patients with HPS compared to the control group (55.1 +/- 7.5 mL vs 37.1 +/- 9.3 mL, P < 0.05). The area under the receiver-operating characteristic (ROC) curve for LAV was 0.903 (Cut point >/= 50 mL, sensitivity 86.3%, specificity 81.2%).

CONCLUSION

In the context of liver cirrhosis, LAV >/= 50 mL is a simple and feasible parameter to detect HPS.

Clinical predictors of atrial fibrillation in Brugada syndrome

AIMS

Atrial arrhythmias have been reported in patients with Brugada syndrome. The aim of this study was to evaluate clinical predictors of atrial fibrillation (AF) in Brugada syndrome.

METHODS AND RESULTS

Patients diagnosed with Brugada ECG pattern were enrolled in the study. Type 1, 2, and 3 Brugada ECG pattern was found in 28, 56, and 31 patients, respectively. A total of 85 healthy age and gender-matched subjects were selected as a control group. Mean age, maximum P-wave duration (P(max)), P-wave dispersion (P(disp)), and left atrial dimension were not significantly different between patients and controls. There were no differences between P(max), P(disp), and left atrial dimension of the type 1, 2, and 3 Brugada patients. Spontaneous paroxysmal AF was detected in 15 of 28 type 1 Brugada patients (53%) and none of the type 2 and 3 Brugada patients. All 15 patients with AF had at least one episode of paroxysmal AF and none of the patients showed persistent or chronic AF. All 15 patients who had paroxysmal AF had previous life threatening cardiac events. In contrast, paroxysmal AF did not occur in type 1 Brugada patients without previous life threatening cardiac events. In multiple regression analysis, only the occurrence of previous life threatening cardiac events was a risk factor for paroxysmal AF (P = 0.0001).

CONCLUSION

It is concluded that the most important predictor of AF in Brugada syndrome is the occurrence of previous life threatening cardiac events.

aVR sign as a risk factor for life-threatening arrhythmic events in patients with Brugada syndrome

BACKGROUND

Risk stratification in Brugada syndrome (BS) is controversial, especially in asymptomatic individuals.

OBJECTIVE

The aim of this study was to evaluate the significance of lead aVR in patients with BS.

METHODS

Twenty-four patients with the electrocardiogram pattern of BS (24 male, mean age 32.1 +/- 13.6 years) and 24 healthy age- and gender-matched controls were studied.

RESULTS

Thirteen patients were symptomatic. The R-wave amplitude or R/q ratio in lead aVR was significantly greater in patients experiencing a recurrence compared with those who did not. The aVR sign was defined as R wave >/= 0.3 mV or R/q >/= 0.75 in lead aVR. Most of the recurrences (78%) were in patients with present aVR sign; 84% of BS patients with present aVR sign had events during follow-up. In contrast, only 27% of BS patients with absent aVR sign had events during follow-up.

CONCLUSION

Our study shows significant correlation between a prominent R wave in lead aVR (aVR sign) and risk for development of arrhythmic events in BS. In the presence of BS, prominent R wave in lead aVR may reflect more right ventricular conduction delay and subsequently more electrical heterogeneity, which in turn is responsible for a higher risk of arrhythmia.

Prevalence of Brugada sign in patients presenting with palpitation in southern Iran

AIMS

Brugada syndrome is a cardiac channel abnormality that is associated with a high risk of ventricular fibrillation and sudden cardiac death and characterized by an electrocardiographic pattern of right bundle branch block and transient or persistent ST-segment elevation in leads V1-V3. No data regarding the frequency of Brugada syndrome exist in an Iranian population. The aim of this study was to determine the frequency of Brugada-type ECG pattern in southern Iran.

METHODS AND RESULTS

All patients presenting with palpitation were enrolled in the study. A Brugada-type ECG pattern was determined according to the criteria recommended by European Heart Association Molecular Basis of Arrhythmias Study Group. A total of 3895 patients (mean age 38.2 +/- 11.9 years, 54% women) met all study criteria. One hundred patients (2.56%) had Brugada-type ECG pattern. Of these, 21 patients (0.54%) had definite Brugada sign (Type 1 or Types 2 and 3 with conversion to Type 1 following procainamide test). Of 21 patients with definite Brugada sign, eight had Brugada syndrome, four had history of syncope, two had coved-type ECG in the family, one had polymorphic ventricular tachycardia, and one had history of sudden cardiac death in the family. Five patients underwent ICD implantation. The incidence of a Brugada-type ECG pattern was 2.43% in subjects between 17 and 30 years and 0.13% in subjects >30 years (P = 0.01).

CONCLUSION

Frequency of Brugada sign in an Iranian population presenting with palpitation is greater than some European countries and lower than a Japanese urban population.

Pharmacokinetics of gallic acid and its relative bioavailability from tea in healthy humans

Gallic acid (GA), a food component that is especially abundant in tea, is an antimutagenic, anticarcinogenic and anti-inflammatory agent. We conducted a study using acidum gallicum tablets that contained 10% GA and 90% glucose and a black tea brew that contained 93% of its GA in free form to determine the pharmacokinetics and relative bioavailability of GA in healthy humans. After the administration of a single oral dose of acidum gallicum tablets or tea (each containing 0.3 mmol GA) to 10 volunteers, plasma and urine samples were collected over various time intervals. Concentrations of GA and its metabolite, 4-O-methylgallic acid (4OMGA), were determined, and the pharmacokinetic parameters were calculated. GA from both the tablets and tea was rapidly absorbed and eliminated with mean half-lives of 1.19 +/- 0.07 and 1.06 +/- 0.06 h and mean maximum concentrations of 1.83 +/- 0.16 and 2.09 +/- 0.22 micromol/L (plasma), respectively. After oral administration of the tablets and black tea, 36.4 +/- 4.5 and 39.6 +/- 5.1% of the GA dose were extracted in urine as GA and 4OMGA, respectively. The relative bioavailability of GA from tea compared with that from the tablets was 1.06 +/- 0.26, showing that GA is as available from drinking tea as it is from swallowing tablets of GA.

Role of nitric oxide in the synthesis of guanidinosuccinic acid, an activator of the N-methyl-D-aspartate receptor

BACKGROUND

We propose that reactive oxygen and argininosuccinic acid (ASA) form guanidinosuccinic acid (GSA). An alternative to this hypothesis is the so-called guanidine cycle, which consists of a series of hydroxyurea derivatives that serve as intermediates in a pathway leading from urea to GSA. We compare the role of the guanidine cycle to that of nitric oxide (NO) in the synthesis of GSA.

METHODS

The members of the guanidine cycle (hydroxyurea, hydroxylamine plus homoserine, L-canaline, and L-canavanine) were incubated with isolated rat hepatocytes. The known NO donors, NOR-2, NOC-7, and SIN-1, were incubated with ASA in vitro. Ornithine, arginine, or citrulline, which increase arginine, a precursor of NO, were incubated with isolated rat hepatocytes. GSA was determined by high-performance liquid chromatography.

RESULTS

None of guanidine cycle members except for urea formed GSA. SIN-1, which generates superoxide and NO formed GSA, but other simple NO donors, did not. Both carboxy-PTIO, a scavenger of NO, and dimethyl sulfoxide, a hydroxyl radical scavenger, completely inhibited GSA synthesis by SIN-1. GSA formation by SIN-1 reached a maximum at 0.5 mmol/L and decreased at higher concentrations. GSA synthesis, stimulated by urea in isolated hepatocytes, was inhibited by ornithine, arginine, or citrulline with ammonia, but not by ornithine without ammonia, where arginine production is limited.

CONCLUSION

GSA is formed from ASA and the hydroxyl radical. When arginine increased in hepatocytes, GSA synthesis decreased. These data suggest that increased NO, which results from high concentrations of arginine, or SIN-1 scavenges the hydroxyl radical. This may explain the decreased GSA synthesis in inborn errors of the urea cycle where ASA is decreased, and also the diminished GSA excretion in arginemia.

The role of protein kinase C in the increased generation in isolated rat hepatocytes of the hydroxyl radical by puromycin aminonucleoside

Puromycin aminonucleoside (PAN) has been known to induce proteinuria. The increased generation of reactive oxygen species (ROS) has been implicated in this toxicity of PAN. We have reported that PAN increases the synthesis of methylguanidine (MG) and creatol which are the products of the reaction of creatinine and the hydroxyl radical in isolated rat hepatocytes. However, the mechanism for the increased ROS induced by PAN is still unclear. In this paper, we investigate the role of protein kinase C (PKC) on the PAN induced reactive oxygen generation in isolated rat hepatocytes. Isolated hepatocytes were incubated in Krebs-Henseleit bicarbonate buffer containing 3% BSA, 16.6 mM creatinine and tested reagents. MG and creatol were determined by high-performance liquid chromatography using 9,10-phenanthrenequinone for the post-labeling. PAN increased MG and creatol synthesis in isolated rat hepatocytes by 60%. 1-(5-Isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7), a PKC inhibitor, at 10 and 100 microM significantly inhibited MG and creatol synthesis with or without PAN. The inhibition rate is dose dependent from 10 to 100 microM. H1004, a reagent used as control for H-7, did not affect (at 10 microM) or increased little (at 100 microM) the synthesis of MG and creatol. Ro31-8425, a potent PKC inhibitor, significantly inhibited (at 10 microM) MG synthesis in the presence of PAN. PKC in the membrane fraction, a marker of PKC activation, increased over the initial concentration by a factor of 1.65-fold at 60 min incubation and 2.16-fold at 120 min with PAN, while it changed little without PAN. These results indicate that PAN activates PKC resulting in increased hydroxyl radical generation in isolated rat hepatocytes.

Formation of guanidinosuccinic acid, a stable nitric oxide mimic, from argininosuccinic acid and nitric oxide-derived free radicals

Guanidinosuccinic acid (GSA) is noted for its nitric oxide (NO) mimicking actions such as vasodilatation and activation of the N-methyl-D-aspartate (NMDA) receptor. We have reported that GSA is the product of argininosuccinate (ASA) and some reactive oxygen species, mainly the hydroxyl radical. We tested for GSA synthesis in the presence of NO donors. ASA (1 mM) was incubated with NOR-2, NOC-7 or 3-morpholinosydomine hydrochloride (SIN-1) at 37 degrees C. GSA was determined by HPLC using a cationic resin for separation and phenanthrenequinone as an indicator. Neither NOR-2 or NOC-7 formed GSA. SIN-1, on the other hand, generates NO and the superoxide anion which, in turn, generated peroxynitrite which was then converted to the hydroxyl radical. Incubation of ASA with SIN-1 leads, via this route, to GSA. When ASA was incubated with 1 mM SIN-1, the amount of GSA produced depended on the incubation time and the concentration of ASA. Among the tested SIN-1 concentrations, from 0.5 to 5 mM, GSA synthesis was maximum at 0.5 mM and decreased with increasing concentrations of SIN-1. Carboxy-PTIO, a NO scavenger, completely inhibited GSA synthesis. SOD, a superoxide scavenger, decreased GSA synthesis by 20%, and catalase inhibited GSA synthesis only by 12%; DMSO, a hydroxyl radical scavenger completely inhibited GSA synthesis in the presence of SIN-1. These data suggest that the hydroxyl radical derived from a combination of NO and the superoxide anion generates GSA, a stable NO mimic. Meanwhile, synthesis of GSA by NO produces reactive oxygen and activates the NMDA receptor that generates NO from GSA, suggesting a positive feed back mechanism.

Determination of gallic acid and its metabolites in human plasma and urine by high-performance liquid chromatography

Gallic acid occurs naturally in plants and has been found to be pharmacologically active as antioxidant, antimutagenic and anticarcinogenic agent. In this work, the metabolism of gallic acid in the human body was investigated. Two methods were developed for the identification and determination of gallic acid and its phenolic metabolites in human plasma and urine by reversed-phase high-performance liquid chromatography using UV detection and involving isocratic elution. One of these methods enables the simultaneous separation and determination of gallic acid (GA), 4-O-methylgallic acid (4OMGA), pyrogallol (PY), 2-O-methylpyrogallol (2OMPY) and resorcinol (RE) in biological fluids. This method is of interest because it allows the separation of a large number of phenolic compounds by isocratic elution using a solution of 4.4 x 10(-3) M phosphoric acid in water as mobile phase. The analysis time for this method, however, is not optimal (57 min). After oral administration of 50 mg GA, 4OMGA rapidly appeared in the plasma and urine besides unchanged GA. Other phenolic compounds, PY, 2OMPY and RE, were not detected. The second method was developed to determine GA and 4OMGA with a short analysis time (25 min).

Determination of some pharmacologically active phenolic acids in juices by high-performance liquid chromatography

Several phenolic acids, e.g. caffeic acid, chlorogenic acid, ferulic acid, gallic acid and ellagic acid, which occur naturally, are inhibitors of carcinogenesis. In this paper we present a new method for the simultaneous determination of all of these compounds, except ellagic acid, in juices by reversed-phase high-performance liquid chromatography (HPLC) using ultraviolet detection and involving isocratic elution, and we have devised an HPLC method for the determination of ellagic acid in juices. The experimental results showed that cherry juice contains a high concentration of chlorogenic acid and the content of bound gallic acid in black and green grape juices is high compared to that of other phenolic acids.