Dependence of the Atrioventricular Conduction Time on the Conduction through the Atrioventricular Node and His-Purkinje System

The electrical depolarization of the heart passes through various structures of the cardiac conduction system, which modify its conduction to different extents. In this study, we investigated the relationship between the atrioventricular conduction time (AV interval) and its contributors, the atrioventricular node (AVN) and the His-Purkinje system (HPS), as represented by the AH and HV intervals, respectively. We also compared sex differences in these intervals and their relations. Resting intracardiac tracings lasting 5 min were obtained from 64 patients (33 women) during an invasive electrophysiological study. The aforementioned intervals were measured for all consecutive beats. The mean AH interval was 85.9 ms, HV 43.7 ms, and AV 129.6 ms. Men had longer AH (80.0 vs. 65.9 ms), HV (38.4 vs. 35.3 ms), and AV intervals (124.7 vs. 108.5 ms) than women. The AV intervals were linearly correlated with AH intervals in all patients (r² = 0.65). No significant correlation was found between AV and HV intervals in all patients (r² = 0.05). There were no sex differences in these associations. Our results suggest that the atrioventricular conduction time depends mainly on the conduction through the AVN and less on the HPS. These relations are similar in both sexes, although men had longer conduction times through the AVN, HPS, and total atrioventricular conduction time.

Double atrial potentials in left-sided accessory pathways are associated with paroxysmal atrial fibrillation

INTRODUCTION

Muscular connections between the coronary sinus (CS) and left atrium probably impact distribution of electrical activity. Double atrial potentials (DP) may be their presentation. The aim was to investigate the presence of DP in CS recordings during atrioventricular reentrant tachycardia (AVRT) and its contribution to the occurrence of paroxysmal atrial fibrillation (AF).

METHODS

A group of 247 patients with accessory pathways (AP) were screened for DP. The patients with DP during AVRT were compared to those without DP.

RESULTS

DP during AVRT were found only among the left-sided AP (AP-L). Patients with AP-L were divided into Group 1 (n  =  17) with DP during AVRT and Group 2 (n  =  108) without DP. Patients in Group 1 had higher incidence of AF in history (47.1% vs. 23.1%; P  =  0.0376), AF induced during electrophysiological (EP) study (70.6% vs. 25%; P  =  0.0002). Group 1 had higher heart rate (HR) during AVRT in the EP study (197.2 ± 27 vs. 175.1 ± 26.3 bpm; P  =  0.0019), but HR of clinical AVRT (208.5 ± 30.8 vs. 191.6 ± 27.8 bpm) was not significant different (P  =  ns). Additionally, electrical alternans of QRS amplitude during AVRT in the EP study was more frequent in Group 1 (52.9 vs. 20.4 %; P  =  0.0048).

CONCLUSION

Patients with DP and AP-L were more prone to develop AF. The presence of DP was associated with faster AVRT rate. The direction of atrium depolarization during AVRT may be different in the presence of DP and probably plays a role in development of AF in this group of patients.

The Management of Supraventricular Tachyarrhythmias in Patients with Pulmonary Arterial Hypertension

BACKGROUND

Atrial remodelling in pulmonary arterial hypertension (PAH) may lead to higher incidence of supraventricular arrhythmias (SVA). The purpose of this study was to evaluate the efficiency and safety of various methods for treatment of SVA in this group.

METHODS

This was a single centre study. Forty-eight patients (33 women and 15 men) aged 19-77 years (median 49 years) were enrolled. There were 30 patients with idiopathic PAH, 10 had PAH associated with connective tissue disease, and eight with congenital heart disease. A retrospective analysis was performed to estimate the prevalence and type of supraventricular arrhythmias, as well as efficiency and safety of treatment methods. Mean follow-up period was 28.8±17.7 months.

RESULTS

Supraventricular arrhythmias occurred in 17 patients (35%) and appeared to be atrial fibrillation, flutter or tachycardia. Supraventricular arrhythmias coexisted with elevated mean right atrial pressure in 75%. Four patients had more than one type of SVA. A flutter-like macro-reentrant form of atrial tachycardia dependent on cavo-tricuspid isthmus was found in four cases. The treatment of SVA included typical methods: antiarrhythmic drugs, direct current cardioversion (DCC), and radiofrequency (RF) ablation. All of the therapeutic methods were effective in managing acute arrhythmia. Three patients required re-ablation. Overall mortality: 14 patients (29%) in the whole study group, including six in SVA group (35%) and eight without SVA (26%).

CONCLUSIONS

In patients with PAH DCC, pharmacological cardioversion and RF ablation can be applied safely and effectively. Flutter-like macro-reentrant atrial tachycardia dependent on cavo-tricuspid isthmus is observed in this group. It is more challenging, but possible, to successfully treat this arrhythmia with RF ablation.

[Unusual epicardial location of ventricular ectopy in left ventricular outflow tract, cured with RF ablation from the great cardiac vein]

The case report refers to a 54-year-old woman with a drug-refractory premature ventricular contractions (total number of ventricular ectopy: 40,851 beats/24 h) where an ectopy focus was localised in epicardial part of the left ventricular outflow tract. Successful radiofrequency ablation with the open-irrigated-tip catheter was performed at the site of earliest activation in the great cardiac vein.

[Unusual picture of pacemaker leads in patient after Senning procedure]

We present a case of a 21-year-old man after Senning operation admitted to our hospital for transvenous implantation of a dual chamber pacemaker. The presence of persistent left superior vena cava enabled us to implant the desired dual chamber pacemaker. It is an extremely unusual situation when two pacemaker leads utilise two different routes to the heart: superior caval vein - atrial baffle - ventricle and persistent left superior caval vein - atrium.

[ST segment elevation typical for Brugada syndrome after intracoronary acetylocholine injection with retrosternal pain in history]

Chest pain is mainly linked with acute coronary syndrome, but sometimes it can be the only manifestation of ventricular tachycardia. We present a case of a young man who was diagnosed with Brugada syndrome after intracoronary acetylocholine injection, with negative test with flecanaide. First manifestation of a disease was a chest pain.

[Contribution of atrioventricular node inputs on orthodromic atrioventricular reentrant tachycardia cycle length]

We describe a 21-year-old woman with a previous history of orthodromic AVRT and overt preexcitation. Electrophysiological study revealed the presence of a left-sided accessory pathway. During an orthodromic AVRT a spontaneous sudden change in heart rate (141 to 202 beats/min) without any change of the QRS morphology was noted due to a decrease in AH interval (from AH=227 ms to AH=100 ms). We explained this phenomenon as the sudden change of the inferior inputs to superior in the AV node.

["Benign" atrial arrhythmias exacerbated by physical activity as a cause of cardiomyopathy]

We describe a 39-year-old man with premature atrial contractions at rest, in whom tachycardia was exacerbated by exercise into long-lasting atrial tachycardia of 150 beats/min with changeable grade of AV conduction. The feeling of irregular heart beating was the only symptom of arrhythmia and was well tolerated for many years. However, the signs of tachycardia-mediated cardiomyopathy with heart failure developed over several years. Successful RF ablation of focal atrial tachycardia using the CARTO system was performed. After 5 months of follow-up the patient is free from arrhythmia with a significant improvement of the HF.

[Atrioventricular nodal tachycardia with left-sided slow pathway treated with RF ablation]

We present a case of 10-year-old boy with AVNRT. The tachycardia had prolonged RP interval (160 ms) and HA time (135 ms). The application at the rim of the coronary sinus resulted in accelerated junctional rhythm and retrograde block followed by transiently prolonged atrioventricular conduction. The mapping of the mitral annulus transeptally presented no 'slow potentials'. The electrode was then inserted retrogradely through the aorta and slow potentials were recorded on the septal aspect of the left atrium. Two RF applications at this site were successful. The patient was followed for three years without recurrence of arrhythmia.

[Presyncope caused by non-sustained ventricular tachycardia. Significance of RF ablation]

We describe a case of a 55-year-old man with episodes of presyncope caused by non-sustained ventricular tachycardia (ns-VT). Symptoms of significant weakness started when he was 30-year-old. In the last 2 years there was a substantial increase in frequency of presyncope from 2 per month to 8 per week. He does not have palpitations. Standard ECG, echocardiography and coronary angiography were normal. During an exercise test ns-VT 220/min (5 s, 20 x QRS) with LBBB morphology was documented. Successful RF ablation of ns-VT using the CARTO system was performed. During 4-month follow-up the patient remains free from ventricular arrhythmia.

Correlation of ST-segment depression during ambulatory electrocardiographic monitoring with myocardial perfusion and left ventricular function

To assess the relation between silent ischemia and objective markers of ischemia we compared ambulatory electrocardiographic (AECG) monitoring, exercise stress testing, and technetium-99m methoxyisobutyl isonitrile single-photon emission computed tomography (SPECT) in 68 patients with coronary artery disease. ST-segment depression at AECG monitoring occurred in 40%, exercise testing was positive in 88%, and SPECT was abnormal in 98% of patients. Patients with ST-segment depression had a higher incidence of 3-vessel disease (70% vs 45%, p = 0.04), shorter duration of exercise (267 +/- 109 vs 416 +/- 167 seconds, p < 0.01), lower workload achieved (5.1 +/- 1.9 vs 7.6 +/- 2.8 METs, p < 0.0002), and a greater extent of ischemia at scintigraphy (p = 0.01). Patients with a total ischemic time of >30 minutes in a 24-hour period had a lower ejection fraction (48 +/- 21% vs 70 +/- 9%, p = 0.001), a higher perfusion index at rest (2.4 +/- 0.6 vs 1.6 +/- 0.6, p = 0.001), and a greater number of segments with fixed perfusion defects (4.1 +/- 3.7 vs 1.3 +/- 1.8, p = 0.02) in comparison with those who had a shorter ischemic time. We conclude that AECG monitoring fails to identify a substantial proportion of patients with objective markers of ischemia; however, ST-segment depression reflects more significant disease. Longer total ischemic time correlates with the area of myocardial damage but not with other markers of ischemia.

[Evaluation of the antihypertensive efficacy of urapidil in the treatment of hypertension emergencies]

Hypertensive crisis is defined as an acute elevation of the blood pressure involving the risk of life. Agents used to the treatment of hypertensive emergencies should lower the blood pressure under control and produce minimal adverse effect. The aim of this study was to evaluate the antihypertensive efficacy of urapidil i.v. in hypertensive emergencies. Twenty three patients (pts) with the hypertensive crisis in association with ischaemic heart disease and/or acute left ventricular failure were studied. Urapidil was given intravenously in the emergent treatment to the group of 23 pts in the mean dose of 50 mg. Systolic (RRs) diastolic blood pressure (RRd) and heart rate were measured within 4 hours after the drug administration. In this group of pts the significant decrease in RRs and RRd after 2 min. of administration of urapidil was observed and the maximum effect (p < 0.05) occurred within 40 min. The heart rate decreased by 8% and was significantly different (p < 0 > 05) at the maximum point of the drug action. Urapidil administered in 25-75 mg i.v. appeared an effective antihypertensive agent in more than 90% of patients with hypertensive emergencies. What was striking, no reflex tachycardia was observed after i.v. administration of urapidil despite its antihypertensive action.

[Non-invasive evaluation of function in both cardiac ventricles and arrhythmias in patients with dilated cardiomyopathy]

Resting echocardiography with M-mode technique under the control of bidimensional picture and pulsating Doppler ultra sound and a 24-hour ECG with Holter technique were performed in 19 patients with dilated cardiomyopathy (6 females and 13 males; mean age 46 years, mean duration of the disease 23 months). A group of 7 patients with electrocardiographic features of the left ventricle hypertrophy, according to Sokolov index, was distinguished and compared with a group of patients without ventricular hypertrophy. The symptoms of pulmonary hypertension with progressing dilatation and failure of the right cardiac ventricle were found in patients with dilated cardiomyopathy without coexisting hypertrophy, despite of significant deterioration of the contractive function. Cardiac arrhythmias and thrombotic disorders which are hazardous for life were significantly more frequent (78% and 22%, respectively) in this group. Percentage of sudden deaths in these patients was high (56%).

[Value of two-dimensional echocardiography in predicting the clinical course and fates of patients 2 years after myocardial infarction]

133 patients with acute myocardial infarction, admitted to hospital 24 hours or less from the beginning of chest pain were investigated. Two-dimensional echocardiography (ECHO 2D) was performed 1-2, 3-5, 7-10, 21-28 days and 3, 6, 9, 12, 18 and 24 months after myocardial infarction. Relations between ECHO parameters, clinical course and prognosis. 2 years after myocardial infarction were analysed. Worse clinical course and prognosis during 2 years after myocardial infarction predict high values of 1) asynergy index (greater than or equal to 1), 2) percentage of asynergy segments (greater than or equal to 50) and 3) percentage of left ventricular (LV) akinetic and (or) dyskinetic segments (greater than or equal to 37.5). Right ventricular asynergy and maintenance or increase of LV asynergy degree aggravate clinical course and prognosis too.