Ultrasonographic diagnosis of delayed atrioventricular conduction during fetal life: a reliability study

OBJECTIVE

The objective of the study was to evaluate the reliability of the 2 most commonly used ultrasonographic approaches for monitoring fetal atrioventricular conduction time (AVCT): (1) superior vena cava/ascending aorta (SVC/AA), and (2) left ventricular inflow/outflow tract (LVI/O) Doppler recordings.

STUDY DESIGN

Echographic studies from fetuses followed up for first-degree atrioventricular block (AVB-1) between 1998 and 2008 were reviewed. The ability to identify atrial contractions in the same fetuses by the SVC/AA and LVI/O approaches was analyzed.

RESULTS

Sixty-six studies of 13 fetuses with AVB-1 were available. Atrial contractions were visible in all SVC/AA studies. With the LVI/O approach, atrial contractions could not be identified in 26 studies (39%). AVCT delay was significantly greater in the nonidentifiable compared with the identifiable atrial contraction group (P < .001). Differences in heart rate and gestational age were not significant.

CONCLUSION

The LVI/O is unsuitable for prenatal screening of conduction system anomalies.

Influence of gestational age and fetal heart rate on the fetal mechanical PR interval

OBJECTIVE

The fetal mechanical PR interval obtained via pulsed Doppler has previously been demonstrated to correlate with electrocardiographic PR interval measured in the neonate. We sought to further analyze the influence of fetal heart rate and gestational age upon the fetal mechanical PR interval.

METHODS

We searched our database for mechanical PR intervals, which were obtained during fetal echocardiography performed in our antenatal diagnostic unit. We included fetuses with a normal cardiac structural survey. The mechanical PR interval is measured from the A wave of the mitral valve to the beginning of ventricular systole corresponding to the opening of the aortic valve. Linear regression curves were generated to examine the correlation of mechanical PR interval with gestational age and fetal heart rate. Analysis of variance was used to compare the mean variation across three gestational age groups: 17-21.9 weeks (n = 24), 22-25.9 weeks (n = 52) and 26-38 weeks (n = 20).

RESULTS

Mechanical PR intervals were measured in 96 fetuses with normal fetal echocardiography. The mechanical PR interval was 123.9 +/- 10.3 ms (mean +/- SD), with a range of 90-150 ms. Linear regression curves correlating mechanical PR interval with fetal heart rate and gestational age demonstrated a flat slope with R2 = 0.016, p = 0.22 and R2 = 0.0004, p = 0.85, respectively. The mechanical PR interval measured over the three gestational ages was as follows (mean +/- SD): 122.3 +/- 10.5 ms for 17-21.9 weeks; 125.0 +/- 9.6 ms for 22-25.9 weeks; and 123.1 +/- 11.9 ms for 26-38 weeks. Analysis of variance revealed no difference among the mechanical PR interval means measured over the three gestational age groups (p = 0.53).

CONCLUSIONS

Fetal mechanical PR interval ranges from 90 to 150 ms in fetuses with sonographically normal fetal cardiac structure and rate. The mechanical PR interval appears to be independent of gestational age and fetal heart rate.

Electromechanical wave imaging of normal and ischemic hearts in vivo

Electromechanical wave imaging (EWI) has recently been introduced as a noninvasive, ultrasound-based imaging modality, which could map the electrical activation of the heart in various echocardiographic planes in mice, dogs, and humans in vivo. By acquiring radio-frequency (RF) frames at very high frame rates (390-520 Hz), the onset of small, localized, transient deformations resulting from the electrical activation of the heart, i.e., generating the electromechanical wave (EMW), can be mapped. The correlation between the EMW and the electrical activation speed and pacing scheme has previously been reported. In this study, we pursue the development of EWI using both displacements and strains and analysis of the EMW properties in dogs in vivo for early detection of ischemia. EWI was performed in normal and ischemic open-chest dogs during sinus rhythm. Ischemia of increasing severity was obtained by gradually obstructing the left-anterior descending (LAD) coronary artery flow. We also introduce the novel method of motion-matching that achieves the reconstruction of the full EWI ciné-loop at very high frame rates even when the ECG may be irregular or unavailable. Incremental displacements were previously used by our group to map the EMW. This paper focuses on the associated incremental strains, which facilitate the interpretation of the EMW by relating it directly to contraction. Moreover, we define the onset of the EMW as the time, at which the incremental strains change sign after the onset of the QRS complex of the ECG. Based on this definition, isochronal representations of the EMW were generated using a semi-automated method. The isochronal representation of the EMW during sinus rhythm was reproducible and shown similar to electrical activation maps previously reported in the literature. After segmentation using a contour-tracking method, the two- and four-chamber views were imaged and displayed in bi-plane views, allowing a 3-D interpretation of the EMW. EWI was shown to be sensitive to the presence of intermediate ischemia. EWI localized the ischemic region when the LAD flow was obstructed at 60% and beyond and was capable of mapping the increase of the ischemic region size as the LAD occlusion level increased. In conclusion, the activation maps and wave patterns obtained with EWI were similar to the electrical equivalents previously reported in the literature. Moreover, EWI was found to be sensitive enough to detect and map intermediate ischemia. Those results indicate that EWI could be used to assess the conduction properties of the myocardium, and detect its ischemic onset and disease progression entirely noninvasively.

Echocardiography as a guidance in CRT management: the GPS system in a labyrinth?

Although progress has been made to understand the factors for non-responsiveness, fine tuning and comprehensive strategies are needed to make echocardiography the GPS system in cardiac resynchronization. Taking the wrong turn in the labyrinth of dyssynchrony is expensive and time consuming without improving well being of the heart failure patient. Possibly other imaging techniques could help in fine tuning cardiac resynchronization.

Fetal Doppler mechanical PR interval: correlation with fetal heart rate, gestational age and fetal sex

OBJECTIVES

To establish normal fetal values for the mechanical PR interval by pulsed-wave Doppler at 16-36 weeks of gestation, and to evaluate the influence of fetal heart rate (FHR), gestational age (GA) and fetal sex.

METHODS

Fetal mechanical PR intervals were evaluated prospectively by obstetric ultrasound examination. Healthy mothers with sonographically normal fetuses from singleton pregnancies were included. Mechanical PR intervals were measured from simultaneous mitral and aortic Doppler waveforms, from the onset of left atrial contraction (mitral A-wave) to the onset of left ventricular ejection (aortic pulse wave). Simple and multiple linear regression analyses were performed to examine the correlation between PR interval and GA, FHR and fetal sex.

RESULTS

We evaluated 336 fetuses at 16-36 weeks. The mean +/- SD FHR was 143.4 +/- 8.3 beats per min (bpm). The PR intervals had a typical Gaussian distribution with a mean +/- SD of 122.4 +/- 10.3 ms. Robust linear regression showed that the PR increased by about 0.40 ms (95% CI, 0.22-0.58) per gestational week (P < 0.001), and this relationship remained after adjustment for FHR and fetal sex. PR intervals diminished by 1.4 (95% CI, 0.75 to 2.0) ms for each 5 bpm increase in FHR (P < 0.001), independently of GA and fetal sex. No fetal sex differences were observed.

CONCLUSIONS

We provide normal fetal values for the mechanical PR interval at 16-36 weeks of gestation. Mechanical PR intervals in normal fetuses are influenced by GA and FHR independently, and both variables should be taken into account when evaluating fetuses at risk for congenital heart block.

Electrocardiographic characteristics at initial diagnosis in patients with isolated left ventricular noncompaction

Isolated ventricular noncompaction (IVNC) is a primary cardiomyopathy characterized by a specific morphologic pattern. Patients with IVNC can develop various arrhythmic complications such as life-threatening ventricular arrhythmias, as well as heart failure or systemic embolic events. The present study was designed to comprehensively analyze the electrocardiographic (ECG) pattern at the initial diagnosis in patients with IVNC and to investigate their correlation with the clinical features and echocardiographic findings. Electrocardiograms from the initial diagnosis of IVNC were available for 78 patients from March 1995 to November 2008. The most common findings were intraventricular conduction delay (especially left bundle branch block), voltage signs of left ventricular (LV) hypertrophy, and repolarization abnormalities. An entirely normal electrocardiogram was present in 10 subjects (13%). However, no ECG findings or patterns specific for IVNC were found. A striking overlap was observed between the presence of intraventricular conduction delay (left bundle branch block, in particular), atrial conduction delay (PR interval prolongation or atrioventricular block), and prolongation of the QTc and reduced systolic LV function and LV/left atrial dilation. Moreover, patients with ECG voltage signs of LV hypertrophy more often presented with, or had a history of, systemic embolic events. In conclusion, our results have provided a comprehensive analysis of ECG findings of patients newly diagnosed with IVNC. Although intraventricular conduction delay, repolarization abnormalities, and LV hypertrophy are frequently present, no ECG patterns specific for IVNC at the first presentation with the disease were found. Whether these findings have prognostic implications needs to be investigated in long-term controlled studies.

Absence of additional improvement in outcome of patients receiving cardiac resynchronization therapy paced at the most delayed left ventricular region

BACKGROUND

The choice of the optimal left ventricular (LV) pacing site remains an issue in patients requiring cardiac resynchronization therapy (CRT).

AIM

This prospective study compared the outcome of patients paced at the most delayed LV region with that of patients paced at any other LV site.

METHODS

Forty-four patients with severe heart failure underwent three-dimensional (3D) echocardiography before implantation and 3 days after implantation of a CRT device, to determine the most delayed LV region during spontaneous rhythm and during right ventricular pacing. The patients were divided subsequently into four groups: group 1 (n=19), LV lead placed at the most delayed echocardiographic site in spontaneous rhythm; group 2 (n=25), LV lead placed at any other site; group 3 (n=21), LV lead placed at the most delayed echocardiographic site during right ventricular pacing; group 4 (n=23), LV lead placed at any other site.

RESULTS

No significant differences were observed between the four groups before implantation. After 6 months of CRT, no significant differences were observed between groups 1 and 2 or between groups 3 and 4 in terms of change in New York Heart Association functional class, Minnesota living with heart failure questionnaire, 6-minute walk test, peak exercise oxygen consumption, 3D ventricular dyssynchrony and 3D LV ejection fraction.

CONCLUSION

Implantation of the LV lead in the most delayed region of the left ventricle determined by 3D echocardiography did not result in additional improvement in symptoms or LV function.

The relationship of myocardial contraction and electrical excitation--the correlation between scintigraphic phase image analysis and electrophysiologic mapping

BACKGROUND

Phase imaging derived from equilibrium radionuclide angiography presents the ventricular contraction sequence. It has been widely but only indirectly correlated with the sequence of electrical myocardial activation.

OBJECTIVES

We sought to determine the specific relationship between the sequence of phase progression and the sequence of myocardial activation, contraction and conduction, in order to document a noninvasive method that could monitor both.

METHODS

In 7 normal and 9 infarcted dogs, the sequence of phase angle was correlated with the epicardial activation map in 126 episodes of sinus rhythm and pacing from three ventricular sites.

RESULTS

In each episode, the site of earliest phase angle was identical to the focus of initial epicardial activation. Similarly, the serial contraction pattern by phase image analysis matched the electrical epicardial activation sequence completely or demonstrated good agreement in approximately 85% of pacing episodes, without differences between normal or infarct groups.

CONCLUSIONS

A noninvasive method to accurately determine the sequence of contraction may serve as a surrogate for the associated electrical activation sequence or be applied to identify their differences.

Cardiac activation mapping using ultrasound current source density imaging (UCSDI)

We describe the first mapping of biological current in a live heart using ultrasound current source density imaging (UCSDI). Ablation procedures that treat severe heart arrhythmias require detailed maps of the cardiac activation wave. The conventional procedure is time-consuming and limited by its poor spatial resolution (5-10 mm). UCSDI can potentially improve on existing mapping procedures. It is based on a pressure-induced change in resistivity known as the acousto-electric (AE) effect, which is spatially confined to the ultrasound focus. Data from 2 experiments are presented. A 540 kHz ultrasonic transducer (f/# = 1, focal length = 90 mm, pulse repetition frequency = 1600 Hz) was scanned over an isolated rabbit heart perfused with an excitation-contraction decoupler to reduce motion significantly while retaining electric function. Tungsten electrodes inserted in the left ventricle recorded simultaneously the AE signal and the low-frequency electrocardiogram (ECG). UCSDI displayed spatial and temporal patterns consistent with the spreading activation wave. The propagation velocity estimated from UCSDI was 0.25 +/- 0.05 mm/ms, comparable to the values obtained with the ECG signals. The maximum AE signal-to-noise ratio after filtering was 18 dB, with an equivalent detection threshold of 0.1 mA/ cm(2). This study demonstrates that UCSDI is a potentially powerful technique for mapping current flow and biopotentials in the heart.

[Intrauterine treatment of incomplete fetal heart block in a mother with Sjögren syndrome]

BACKGROUND

Isolated fetal heart block is considered as an immunological disorder in the majority of cases. Mothers of affected fetuses often suffer from connective tissue disease (Sjögren syndrome or Lupus erythematodes). All of them test positive for anti-SS-A (anti Ro) and/or anti-SS-B (anti La) antibodies. Once established, third-degree congenital heart block is permanent and often requires a pacemaker.

CASE

We report on a pregnancy in a mother with Sjögren syndrome which was complicated by the development of incomplete fetal heart block, diagnosed by pulsed wave Doppler echocardiography. We started oral dexamethasone treatment to reduce immune-mediated fetal cardiac damage and to prevent complications like hydrops fetalis.

CONCLUSION

Detection of isolated fetal heart block is possible with pulsed Doppler sonography, but there are no clear recommendations for treatment.

Noninvasive three-dimensional cardiac activation imaging from body surface potential maps: a computational and experimental study on a rabbit model

Three-dimensional (3-D) cardiac activation imaging (3-DCAI) is a recently developed technique that aims at imaging the activation sequence throughout the the ventricular myocardium. 3-DCAI entails the modeling and estimation of the cardiac equivalent current density (ECD) distribution from which the activation time at any myocardial site is determined as the time point with the peak amplitude of local ECD estimates. In this paper, we report, for the first time, an in vivo validation study assessing the feasibility of 3-DCAI in comparison with the 3-D intracardiac mapping, for a group of four healthy rabbits undergoing the ventricular pacing from various locations. During the experiments, the body surface potentials and the intramural bipolar electrical recordings were simultaneously measured in a closed-chest condition. The ventricular activation sequence noninvasively imaged from the body surface measurements by using 3-DCAI was generally in agreement with that obtained from the invasive intramural recordings. The quantitative comparison between them showed a root mean square (rms) error of 7.42 +/-0.61 ms, a relative error (RE) of 0.24 +/-0.03, and a localization error (LE) of 5.47 +/-1.57 mm. The experimental results were also consistent with our computer simulations conducted in well-controlled and realistic conditions. The present study suggest that 3-DCAI can noninvasively capture some important features of ventricular excitation (e.g., the activation origin and the activation sequence), and has the potential of becoming a useful imaging tool aiding cardiovascular research and clinical diagnosis of cardiac diseases.

Model-based imaging of cardiac apparent conductivity and local conduction velocity for diagnosis and planning of therapy

We present an adaptive algorithm which uses a fast electrophysiological (EP) model to estimate apparent electrical conductivity and local conduction velocity from noncontact mapping of the endocardial surface potential. Development of such functional imaging revealing hidden parameters of the heart can be instrumental for improved diagnosis and planning of therapy for cardiac arrhythmia and heart failure, for example during procedures such as radio-frequency ablation and cardiac resynchronisation therapy. The proposed model is validated on synthetic data and applied to clinical data derived using hybrid X-ray/magnetic resonance imaging. We demonstrate a qualitative match between the estimated conductivity parameter and pathology locations in the human left ventricle. We also present a proof of concept for an electrophysiological model which utilizes the estimated apparent conductivity parameter to simulate the effect of pacing different ventricular sites. This approach opens up possibilities to directly integrate modelling in the cardiac EP laboratory.

Intracardiac echocardiography-facilitated ablation of a left-lateral bypass tract in a patient with atrial septal aneurysm

Intracardiac echocardiography (ICE) has been used as an adjunctive tool during electrophysiological procedures, mainly to increase the safety of transseptal puncture. We present the case of a young patient with a left-lateral bypass tract and atrial septal aneurysm, in whom ICE delineated the underlying anatomy, excluded the presence of thrombus and facilitated access to the left atrium through a small atrial septal defect, avoiding the risk of needle puncture for interatrial septal crossing.

[Clinical implications and angiographic and electrocardiographic correlation of ST segment elevation in leads V7-V9 in patients with ST elevation myocardial infarction]

INTRODUCTION

The clinical significance and clinical characteristics of patients with myocardial infarction involving the posterior wall of the left ventricle is not well-defined. The angiographic findings and their correlation with the eletrocardiographic (ECG) findings may be of high therapeutic importance.

METHODS

We retrospectively studied consecutive patients with ST elevation myocardial infarction on the admission ECG to the intensive cardiac care. We studied the clinical and demographic characteristics, the clinical course in-hospital and the clinical outcome (including infarct size, congestive heart failure and significant mitral insufficiency). All patients underwent coronary angiography during the index admission. We correlated the ECG findings on admission to the angiographic findings.

RESULTS

We studied 198 patients with mean age of 57 +/- 12 years (range 30-88 years), 158 men (79.8%) and 40 women (20.2%). Myocardial infarction involving the inferior wall was noted in 119 patients, of whom 68 had inferior wall myocardial infarction only, and 51 had inferior and lateral wall involvement (leads I, AVL and/or V5-V6). Only 4 patients (2%) had ST elevation in leads V7-V9 only. The left ventricular ejection fraction was lowest in patients with anterior wall myocardial infarction (41% +/- 6) compared to myocardial infarction with the posterior wall involved (44% +/- 8) or myocardial infarction with the inferior wall only (54% +/- 6) (p = 0.023). The largest infarct size by peak creatine phosphokinase was found in the inferoposterior myocardial infarction group, significantly larger from inferior infarction only, and similar to that of anterior myocardial infarction. The incidence of congestive heart failure was slightly more in anterior myocardial infarction; however, significant mitral valve insufficiency was higher in patients with posterior wall involvement, yet with no statistical significance. The infarct related artery causing posterior myocardial infarction was significantly more frequent in the right coronary artery (57.1%) compared to the left circumflex artery (37.5%) (p < 0.01).

CONCLUSIONS

The major artery causing involvement of the posterior wall is the right coronary artery. In patients with myocardial infarction involving the posterior wall, infarct size is similar to that of anterior wall myocardial infarction, and with similar complications rate. However, the incidence of significant mitral valve insufficiency and congestive heart failure is high in patients with posterior wall involvement. Posterior leads assessment should be conducted routinely in patients with suspected myocardial infarction.

Association of visual hallucinations with reduction of MIBG cardiac uptake in Parkinson's disease

BACKGROUND

Postganglionic cardiac sympathetic denervation is evident in patients with Parkinson's disease (PD) and iodine-123 metaiodobenzylguanidine ((123)I-MIBG) cardiac scintigraphy has proven to be a useful tool for diagnosis of PD.

OBJECTIVE

To elucidate the factors associated with severity of cardiac sympathetic nerve dysfunction in PD patients.

METHODS

We investigated 95 PD patients hospitalized in the Department of Neurology at Tottori University Hospital. (123)I-MIBG cardiac scintigraphy was performed on each patient and the early and delayed heart to mediastinum (H/M) ratios and washout rate (WR) of (123)I-MIBG cardiac scintigraphy were calculated. Independent predictive variables for parameters of (123)I-MIBG cardiac scintigraphy were analyzed by multivariate regression analysis.

RESULTS

Multivariate regression analysis revealed that the presence of visual hallucinations (VH) and the patient's age at the time of evaluation independently predicted the early or delayed H/M ratio. Analysis of covariance, adjusted for the age of the patients as covariates, revealed that the early and delayed H/M ratios of PD patients with VH but no dementia, as well as PD patients with dementia were significantly lower than the ratios in PD patients with no VH or dementia.

CONCLUSION

Cardiac sympathetic dysfunction may be associated with the presence of VH in PD patients.

Noninvasive estimation of three-dimensional cardiac electrical activities from body surface potential maps

A noninvasive three-dimensional (3D) cardiac electrical imaging (3DCEI) approach, which can estimate the location of the initiation site (IS) of activation and the resultant 3D activation sequence (AS) from body surface potential maps (BSPMs), was validated in an intact large mammalian model (swine) during acute ventricular pacing. Body surface potential mapping and intracavitary noncontact mapping (NCM) were performed simultaneously during pacing from both right ventricular (RV) sites (intramural) and left ventricular (LV) sites (endocardial). Subsequent 3DCEI analyses were performed on the measured BSPMs. In total, 5 RV and 5 LV sites from control and heart failure animals were paced. The averaged localization error of the RV and LV sites were 7.0+/-1.1 mm and 6.6+/-1.9 mm, respectively. The endocardial ASs as a subset of the estimated 3D ASs by 3DCEI were consistent with those reconstructed from the NCM system. The present experimental results demonstrate that the noninvasive 3DCEI approach can localize the initiation site and estimate cardiac activation sequence with good accuracy in an in vivo setting, under control, paced and/or diseased conditions.

Intracardiac echocardiography in electrophysiology

Intracardiac echocardiography (ICE) broadens the spectrum of echocardiographic techniques. Modern 10F sector echocardiographic catheters introduced into the right atrium allow high quality imaging of all cardiac structures, including pulse and continuous wave Doppler and/or color Doppler. The main indication for ICE appears to be monitoring of catheter ablation of complex arrhythmic substrates such atrial fibrillation, postincisional tachycardias and ventricular tachycardias. The other important role of ICE is the early diagnosis and prevention of complications during ablation procedures. These include those occurring during transseptal catheterization, damage to cardiac structures, left atrial thrombus formation, pulmonary venous stenosis, esophageal injury and pericardial effusion.

N-Terminal Pro Brain Natriuretic Peptide to Predict Prognosis in Dilated Cardiomyopathy with Sinus Rhythm

AIMS

To assess the value of plasma NT proBNP levels for predicting adverse outcomes in patients with dilated cardiomyopathy (DCM).

METHODS

Seventy-eight patients with DCM (EF <40%) with sinus rhythm were enrolled. All patients had undergone echocardiographic examination, coronary angiography, and cardiac catheterisation. Blood samples for plasma NT proBNP levels were taken at rest following echocardiographic examination. Patients were followed up for 660+/-270 days for clinical endpoints defined as; death from worsening heart failure, sudden cardiac death and heart transplantation (Tx).

RESULTS

Clinical end points were observed in 19 patients (5 Tx, 4 sudden cardiac death, 10 death from worsening heart failure). Variables associated with an increased hazard of clinical endpoints in univariate analysis were log NT proBNP, age, NYHA functional class, left ventricle ejection fraction, mitral valve effective regurgitation orifice area, and E wave deceleration time. The plasma level of NT proBNP (Hazard ratio=2.5 [95% CI: 1.3-4.7], p=0.0024) and age (hazard ratio=0.94 [95% CI: 0.90-0.98], p=0.0005) were the independent variables associated with an increased risk of clinical endpoints. NT proBNP plasma level >4500 pg/ml detected patients with clinical endpoints with a sensitivity, and specificity of 72%, 80%, respectively. The event free survival was found to be significantly lower in patients with NT proBNP levels >4500 pg/ml.

CONCLUSION

NT proBNP seems to be a strong predictor of adverse outcomes in patients with DCM with sinus rhythm and may be used as a reliable biological marker in risk stratification.

Detection of the cardiac activation sequence by novel echocardiographic tissue tracking method

Asynchronous cardiac activation leads to decreased pumping efficiency. Quantifying the activation sequence may optimize both the selection of patients for cardiac resynchronization therapy (CRT) and its efficacy. The feasibility of assessing the directivity and the degree of synchronous activation with ultrasound was examined. A tissue tracking method (CEB, GE-Ultrasound, AFI, GE Healthcare Inc., Wauwatosa, WI, USA) provided the regional strain profiles. The first maxima in systole of the regional circumferential strains were considered as the activation times. An integrative vector (SDV) describes the activation synchrony and directivity. In six open-chest sheep, activation maps and SDV were calculated in short-axis planes of the left ventricle for normal activation and induced pacings from the anterior and lateral free walls. Both magnitude and angle of the SDV were statistically different (p < 0.05) for the different pacings. Localization of the pacing site was 3 degrees +/- 18 degrees from true position. Conclusions were that motion analysis in echocardiograms provides insightful information regarding the activation process and may enhance procedures such as CRT.

Usefulness and safety of transcatheter ablation of atrial fibrillation in patients with hypertrophic cardiomyopathy

Atrial fibrillation (AF) is common in patients with hypertrophic cardiomyopathy (HC) and predicts adverse outcome. Radiofrequency catheter ablation (RFCA) represents a potentially advantageous alternative to lifelong pharmacologic treatment. However, its efficacy in patients with HC is not established. In the present study, the feasibility, safety, and efficacy of RFCA of AF in patients with HC were evaluated. Twenty-six patients with HC with paroxysmal (n = 13) or permanent (n = 13) AF refractory to antiarrhythmic therapy (age 58 +/- 11 years, time from AF onset 7.3 +/- 6.2 years, left atrial volume 170 +/- 48 ml) underwent RFCA. A schema with pulmonary vein isolation plus linear lesions was used. No major periprocedural complication occurred. One patient died from a hemorrhagic stroke 4 weeks after RFCA while in sinus rhythm. During a 19 +/- 10-month follow-up, 9 of the remaining 25 patients (36%) experienced recurrence of AF (despite repeated RFCA in 3) and were considered failures, whereas 16 remained in sinus rhythm (i.e., 64% overall success rate). Ten of these 16 patients were off antiarrhythmic drug therapy at final evaluation. RFCA was highly successful in patients with paroxysmal AF (77% success rate compared with 50% in the subgroup with permanent AF). Patients with restoration of sinus rhythm showed marked symptomatic improvement (final New York Heart Association functional class 1.2 +/- 0.5 vs 1.7 +/- 0.7 before the procedure, p = 0.003). Conversely, patients for whom RFCA failed showed no change (final functional class 1.9 +/- 0.8 vs 1.7 +/- 0.9 before the procedure, p = 0.59). In conclusion, in most studied patients with HC, RFCA proved a safe and effective therapeutic option for AF, improved functional status, and was able to reduce or postpone the need for long-term pharmacologic treatment.

Vagal responses induced by endocardial left atrial autonomic ganglion stimulation before and after pulmonary vein antrum isolation for atrial fibrillation

BACKGROUND

Elimination of vagal inputs into the left atrium (LA) may be necessary for successful catheter ablation of atrial fibrillation (AF). These vagal inputs are clustered in autonomic ganglia (AG) that are close to the pulmonary vein antrum (PVA) borders, but whether standard intracardiac echocardiography (ICE)-guided PVA isolation (PVAI) affects these inputs is unknown.

OBJECTIVE

The purpose of this study was to assess whether standard ICE-guided PVAI affects vagal responses induced by endocardial AG stimulation in the LA.

METHODS

Twenty consecutive patients undergoing first-time PVAI (group 1) and 20 consecutive patients undergoing repeat PVAI for AF recurrence (group 2) were enrolled in the study. Before ablation, electrical stimulation (20 Hz, pulse duration 10 ms, voltage range 12-20 V) was performed through an 8-mm-tip ablation catheter. Based on prior data, regions around all four PVA borders were carefully mapped and stimulated to localize AG inputs. A positive stimulated vagal response was defined as atrioventricular (AV) block, asystole, or increase in mean RR interval by >50%. Locations of positive vagal responses were recorded wth biplane fluoroscopy and CARTO. All patients then underwent standard ICE-guided PVAI by an operator blinded to the locations of vagal responses. Stimulation of the AG locations was then repeated postablation.

RESULTS

Patients (age 54 +/- 11 years, 30% female, ejection fraction 54% +/- 7%) had a history of paroxysmal (75%) and persistent (25%) AF. In group 1, vagal responses were induced in all 20 patients around a mean of 3.8 +/- 0.4 PVAs per patient. The most common response was asystole (53%), mean RR slowing >50% (28%), and AV block (20%). Postablation, vagal responses could no longer be induced in all 20 patients. A diminished response was induced (RR slowing <50%) in 2/20 patients around one PVA each. In group 2, vagal responses were not induced in any of the 20 repeat patients. Stimulation capture postablation was confirmed because transient, nonsustained (<30 seconds) AF or atrial flutter was induced in all 40 patients with stimulation, whether vagal responses were induced or not.

CONCLUSIONS

Standard ICE-guided PVAI eliminates vagal responses induced by AG stimulation. Responses are not seen in patients presenting for repeat PVAI, despite clinical recurrence of AF.

Prevalence of Dyssynchrony Derived from Echocardiographic Criteria in Heart Failure Patients with Normal or Prolonged QRS Duration

Cardiac resynchronization therapy (CRT) for heart failure is targeted at specific patients with mechanical dyssynchrony. We aimed to evaluate the prevalence of dyssynchrony in heart failure patients with either normal or prolonged QRS duration using Doppler imaging. Sixty heart failure patients with idiopathic dilated cardiomyopathy (30 with prolonged QRS duration 30 with normal QRS duration) underwent standard echocardiography and tissue Doppler imaging examinations. Difference between left and right ventricular pre-ejection intervals of more than 40 msec was considered a marker of interventricular dyssynchrony. Intraventricular dyssynchrony was defined as a delay of 60 msec between the time to peak velocities of the septum and left ventricular lateral wall. Patients who have either intra- or interventricular dyssynchrony were defined as with cardiac dyssynchrony. Dyssynchrony was observed in 7 (23.3%) heart failure patients with normal QRS duration versus 26 (86.7%) patients with prolonged QRS duration. There was significant difference between the prevalence of dyssynchrony derived from echo criteria in two groups (P<0.05). Although patients with prolonged QRS duration have a high prevalence of dyssynchrony, yet some still have good cardiac synchronicity. Moreover, dyssynchrony also exists in a small percentage of heart failure patients with normal QRS duration. To identify the potential responders for CRT, both QRS duration and cardiac synchronicity should be assessed.

Assessment of cardiac asynchrony by radionuclide phase analysis: correlation with ventricular function in patients with narrow or prolonged QRS interval

BACKGROUND

Conflicting data exist on the relation between the synchronism of cardiac contraction and ventricular function.

AIM AND METHODS

A resting radionuclide ventriculography (RNV) was performed in 380 consecutive patients to evaluate the relationship between the synchronism of cardiac contraction and ventricular function.

RESULTS

A significant, non-linear, relation was found between LVEF and intra-ventricular asynchrony or QRS, but not between inter-ventricular asynchrony and LVEF. A linear correlation was observed between QRS and intra-ventricular or inter-ventricular asynchrony. Intra-ventricular asynchrony was identified as the major, independent, determinant of LV function. With the increase in QRS duration, a decrease in LVEF (p<0.001), and a worsening of either intra-ventricular (p<0.001) or inter-ventricular synchronism (p<0.05), was documented. However, 48% of patients with QRS 120-150 ms had abnormal inter-ventricular and 42% abnormal intra-ventricular synchronism, while 27% of patients with QRS>150 ms had normal inter-ventricular and 25% normal intra-ventricular synchronism.

CONCLUSIONS

Intra-ventricular asynchrony was identified as the major determinant of ventricular dysfunction. A consistent proportion of patients had asynchrony despite preserved QRS duration or normal synchronism with a QRS>150 ms. Fourier phase analysis of RNV may detect asynchrony better than QRS. The role of RNV for detection of individual patients who may most benefit from resynchronization therapy requires additional investigations.