Electrophysiological features in patients with sinus node dysfunction and vasovagal syncope.

INTRODUCTION: Syncope is a common presentation of sinus node dysfunction (SND). Some patients who receive a permanent pacemaker due to SND do not benefit from it and further diagnostic workup leads to the diagnosis of vasovagal syncope (VVS). The aim of the study was to identify electrophysiological criteria that can be used for identification of patients with SND and concurrent VVS. MATERIAL AND METHODS: Transoesophageal atrial pacing (TAP) was performed in 100 patients divided into four groups depending on symptoms and TAP results. Standard electrophysiological parameters of sinus node function and their variability were obtained in the basal state and after pharmacological autonomic blockade (AB). RESULTS: Patients with concurrent SND and VVS had a greater variability of sinoatrial conduction time assessed by Strauss' method than patients without incidents of syncope (83.2 ±53.9 vs. 34.1 ±19.6, 47.8 ±33.6 and 32.1 ±22.99). Apart from abnormal sinus node recovery time and second pause, patients with SND had bigger basal state variability of these parameters. In patients with SND and concurrent vasovagal syncope the variability of sinus node recovery time (SNRT), corrected SNRT (cSNRT) and second pause (IIP) decreased after autonomic blockade. CONCLUSIONS: Patients with concurrent SND and VVS have distinct electrophysiological features - greater sinoatrial conduction time (SACT) variability and the decrease of SNRT, cSNRT and IIP variability after AB. However, further studies in larger study groups are needed to validate our findings. Transoesophageal atrial pacing is a useful procedure in patients with syncope, especially when the coexistence of more than one cardiac cause is suspected.

Survival analysis in patients with preserved left ventricular function and standard indications for permanent cardiac pacing randomized to right ventricular apical or septal outflow tract pacing.

BACKGROUND: Optimal right ventricular (RV) pacing site in patients referred for permanent cardiac pacing remains controversial. A prospective randomized trial was done to compare long-term effect of permanent RV apex (RVA) vs RV outflow tract (RVOT) pacing on the all-cause and cardiovascular mortality. METHODS AND RESULTS: A total of 122 consecutive patients (70 men, 69 +/-11 years), with standard pacing indications were randomized to RVA (66 patients) or RVOT (56 patients) ventricular lead placement. After the 10-year follow-up period the mortality data were summarized on the basis of an intention-to-treat analysis. During the long-term follow-up, 31 patients from the RVA group died vs 24 patients in the RVOT group (hazard ratio (HR), 0.96; 95% confidence interval (CI), 0.57-1.65; P=0.89). There were 10 cardiovascular deaths in the RVA and 12 in the RVOT group (HR, 1.04; 95%CI, 0.45-2.41; P=0.93). There were no differences in the all-cause or cardiovascular mortality between the pacing sites after adjustment for age, gender, arterial hypertension, atrial fibrillation, New York Heart Association class and left ventricular end-diastolic diameter. CONCLUSIONS: The RVOT provides no additional benefit in terms of long-term survival over RVA pacing.

Right ventricular apex versus right ventricular outflow tract pacing: prospective, randomised, long-term clinical and echocardiographic evaluation.

INTRODUCTION: In patients treated with permanent pacing, the electrode is typically placed in the right ventricular apex (RVA). Published data indicate that such electrode placement leads to an unfavourable ventricular depolarization pattern, while right ventricular outflow tract (RVOT) pacing seems to be more physiological. AIM: To compare long-term effects of RVOT versus RVA pacing on clinical status, left ventricular (LV) function, and the degree of atrioventricular valve regurgitation. METHODS: Patients with indications for permanent pacing, admitted to hospital between 1996 and 1997, were randomised to receive RVA or RVOT pacing. In 2004 during a final control visit in 27 patients clinical status, echocardiographic parameters and QRS complex duration as well as NT-proBNP level were measured. Analysed parameters were compared between groups and in the case of data available during the perioperative period also their evolution in time was assessed. RESULTS: Out of 27 patients 14 were randomised to the RVA group and 13 to the RVOT group. No significant differences between groups were observed before the procedure with respect to age, gender, comorbidities or echocardiographic parameters. Mean duration of pacing did not differ significantly between the groups (89+/-9 months in RVA group vs 93+/-6 months in RVOT group, NS). In the RVA group significant LV ejection fraction decrease was observed (from 56+/-11% to 47+/-8%, p <0.05); in the RVOT group LV ejection fraction did not change (54+/-7% and 53+/-9%; NS). Progression of tricuspid valve regurgitation was also observed in the RVA group but not in the RVOT group. During the final visit NT-proBNP level was significantly higher in the RVA group: 1034+/-852 pg/ml vs 429+/-430 pg/ml (p <0.05). CONCLUSIONS: In patients with normal LV function permanent RVA pacing leads to LV systolic and diastolic function deterioration. RVOT pacing can reduce the unfavourable effect and can slow down cardiac remodelling caused by permanent RV pacing. Clinical and echocardiographic benefits observed in the RVOT group after 7 years of pacing are reflected by lower NT-proBNP levels in this group of patients.

Biventricular pacing demonstrates similar effects in elderly and younger patients with advanced heart failure in the mid-term follow-up.

BACKGROUND: Biventricular (BIV) pacing has been shown to improve haemodynamics and functional status of patients (pts) with advanced chronic heart failure (CHF). No study has determined the effects of BIV in relation to the age of pts. AIM: To compare the clinical outcome in two groups of pts: > or =65 years (yrs) and <65 yrs referred for BIV pacing in our centre with at least 6 months of follow-up. METHODS: Among 15 pts > or =65 yrs and 16 pts <65 yrs successfully implanted with a BIV pacemaker, 12 and 15 pts, respectively, completed 6-month follow-up. Evaluation included change of NYHA class, 6-minute walking distance (6-minWD), drug therapy, QRS duration and echocardiographic parameters. The need for hospitalisation due to the worsening of CHF symptoms, assessed 6 months before and 6 months after BIV pacing, was compared. During long-term follow-up survival and complications related to this therapy were analysed. RESULTS: In both groups after 6 months of BIV pacing clinical improvement was observed, as demonstrated by the reduction in NYHA class (p <0.005), average duration of hospitalisation due to CHF (p <0.05) and diuretics doses (p <0.05). The comparison of changes in these parameters between the two groups, as well as of changes in 6-minWD and echocardiographic parameters, did not show significant difference. BIV pacing enabled an increase in the dosage of beta-blockers (in 50% pts > or =65 yrs and 60% pts <65 yrs), as well as of ACEI or ARB (25% and 40% pts, respectively). Survival was 80% in 15 pts > or =65 yrs during 16+/-15 months of follow-up and 81% in 16 pts v65 yrs during 22+/-14 months. All complications occurred in the 30-day post-operative period with similar frequency in both groups, also when LV lead-related complications were compared. CONCLUSIONS: In the mid-term follow-up BIV pacing demonstrates similar improvement in clinical status and exercise tolerance in elderly pts > or =65 yrs, as compared with pts <65 yrs. In both groups BIV pacing reduced the need for hospitalisation due to worsening of CHF symptoms, and enabled beneficial changes in the pharmacological treatment. Elderly patients are not at risk of more frequent complications associated with BIV pacing.

Comparison of defibrillation efficacy using implantable cardioverter-defibrillator with single- or dual-coil defibrillation leads and active can.

INTRODUCTION: The reduction of defibrillation threshold (DFT) in patients treated with an implantable cardioverter-defibrillator increases patients' safety and prolongs ICD battery life. AIM: To evaluate the possibility of reducing the defibrillation threshold in ICDs with an active can and an additional atrial defibrillation coil instead of the typical intracardiac single-coil lead. METHOD: This study involved 138 patients (36 F and 102 M, mean age 54+/-15 years) including 62 subjects with dual-coil defibrillation lead (group A) and 76 ones with single-coil defibrillation lead (group B). No statistically significant differences with respect to age, left ventricular function, main disease or exacerbation of heart failure according to the NYHA functional class were observed between groups. The defibrillation threshold was measured using the DFT+ protocol. RESULTS: No significant differences between groups were identified with respect to pacing and sensing parameters. The comparison of DFT values between the two studied groups revealed significant improvement (by 14% mean) of defibrillation efficacy in group A. In group A, the mean DFT was 9.8+/-4.6 J (3-20 J) and mean defibrillation resistance - 45+/-7 W (32-73 W), whereas in group B: 11.45+/-5.25 J (3-28 J) and 72+/-12.8 W (38-106 W), respectively. In 93% of patients from group A, DFT was below 15 J, in comparison to 81% of patients from group B (p=0.046). The odds ratio of a higher defibrillation threshold (l15 J) in group A vs. group B was 0.3 (95% confidence interval: 0.09-0.98). The DFT reduction associated with modified ICD system use was independent of following clinical parameters: patient age, gender, main disease, end-diastolic left ventricular diameter, left ventricular ejection fraction, NYHA functional class and concomitant treatment with antiarrhythmic agents. CONCLUSIONS: Modification of the electric field during defibrillation, achieved with the use of active-can ICDs with dual-coil defibrillation leads, allows a reduction of DFT by 14%. At the same time, it reduces the risk of a higher (> or =15 J) DFT by three times compared to patients with a standard single-coil defibrillation lead.

Clinical predictors of defibrillation threshold in patients with implantable cardioverter-defibrillators.

BACKGROUND: Safety of patients with malignant ventricular arrhythmias, treated with implantable cardioverter defibrillators (ICD), depends on the possibility of immediate and effective intracardiac defibrillation. It is especially important in those patients in whom there is a risk of increased defibrillation threshold (DFT) of ventricular fibrillation (VF). Thus, it is important to know whether some clinical parameters may predict a high DFT. AIM: To assess the relationship between DFT and clinical, demographic and anthropometric parameters, type and progression of underlying disease as well as antiarrhythmic therapy used in ICD recipients. METHODS: The study group consisted of 168 patients (47 females, 121 males, mean age 55+/-15 years, range 15-82 years) who were selected to receive an ICD. DFT was systematically tested during ICD implantation in all patients. Various clinical, demographic, anthropometric and echocardiographic parameters were analysed as the function of DFT value, examining their accuracy in predicting a high (> or =15 J) or a low (<15 J) DFT, using logistic regression model. RESULTS: Univariate analysis revealed that DFT value was significantly related to the following parameters: idiopathic VF, dilated cardiomyopathy, amiodarone therapy and the use of beta blockers. There was a significant correlation between DFT and LVEDD, height, LVEF and impedance of defibrillating system. Multivariate analysis showed that amiodarone therapy, height, impedance of defibrillating system and LVEDD were independently related to the DFT value. Parameters which predicted a high (> or =15 J) DFT, consisted of amiodarone therapy (p=0.005), height (p=0.01), LVEDD (p=0.01), LVEF (p=0.03), dilated cardiomyopathy (p=0.01) and body surface area (p=0.049). Amiodarone therapy occurred to be the only parameter which independently predicted a high DFT (odds ratio 2.78; 95% confidence interval 1.19-6.5). CONCLUSIONS: Tall stature, enhanced LVEDD, decreased LVEF and amiodarone therapy increase the risk of a high DFT in ICD recipients. Chronic amiodarone therapy increases three times the risk of elevated DFT. In patients with already implanted ICD in whom amiodarone is started, reassessment of DFT following administration of a loading dose of the drug is required.

Different predictive values of electrophysiological testing and autonomic assessment in patients surviving a sustained arrhythmic episode.

BACKGROUND: Recent data suggest that the electrophysiological study (EPS) has limited value in the identification of high risk patients, so the aim of the present study was to evaluate if non-invasive measurement of baroreflex sensitivity (BRS), a marker of autonomic balance, provides additional prognostic information in patients surviving a sustained arrhythmic episode. METHODS AND RESULTS: The study group comprised 112 post myocardial infarction patients consecutively referred for EPS following documented ventricular fibrillation (VF) (20), sustained ventricular tachycardia (VT) (74) or a syncopal episode with subsequently documented non-sustained VT at Holter monitoring (18). BRS was assessed according to the transfer function method. A cardioverter - defibrillator (ICD) was implanted in 97 patients. During follow-up (median 315 days), appropriate ICD discharge occurred in 53 patients, and 3 more patients died suddenly. Sustained VT was induced in 84% and 77% of patients who did or did not develop arrhythmia at follow-up (p=0.34). No differences were found in age, sex, infarct site, drug therapy, resting RR interval or cycle of induced VT. Left ventricular ejection fraction (LVEF) < or =35%, New York Heart Association (NYHA) class >2 and BRS < or =3.3 ms/mmHg were found to be univariate predictors of arrhythmia recurrence. Multivariate models were obtained after grouping patients according to a moderately or severely depressed LVEF. Among the patients with LVEF < or =35%, BRS < or =3.3 ms/mmHg emerged as the only significant risk predictor of arrhythmia occurrence (sensitivity, specificity, positive and negative predictive value = 79%, 74%, 83% and 68%, respectively), whereas NYHA class >2 was a significant predictor among patients with LVEF >35%. CONCLUSIONS: Noninvasive BRS, but not EPS, is of value in predicting VT/VF episode recurrence in patients surviving a major arrhythmic event.

[Attempt to assess the risk of recurrence of life-threatening ventricular arrhythmia using simple non-invasive tests]. / Próba oceny ryzyka nawrotu zlosliwej arytmii komorowej na podstawie prostych nieinwazyjnych badan diagnostycznych.

UNLABELLED: Baroreflex sensitivity (BRS), as assessed using phenylephrine method, and depressed 24-hour heart rate variability (HRV) have been shown to be powerful predictors of life-threatening ventricular arrhythmias. However, before these tests are widely used, their methodology has to be simplified. The aim of this study was to assess the prognostic value of simple non-invasive BRS parameter (Robbe index, BRS-RI) and short-term HRV, together with left ventricular ejection fraction (LVEF) and late potentials (LP) assessment in patients after myocardial infarction (MI) with documented history of ventricular tachycardia (VT) and ventricular fibrillation (VF). MATERIAL AND METHODS: The observation was conducted on 53 patients after MI with documented VT or VF. They were was divided into two groups: with or without recurrence arrhythmia. During the follow-up malignant ventricular arrhythmia events occurred in 31 patients VT/VF(+), no VT or VF was recorded in the 22 subjects VT/VF(-). In all patients the following parameters were analyzed: BRS-RI (transfer function, 0.07-0.14 Hz), HRV parameters such as: SDNN, rMSSD, pNN50, LF LF (NU), LF/HF. Additionally, LVEF and LP were assessed. RESULTS: In the VT/VF(+) and VT/VF(-) groups, values of analyzed parameters were: BRS-RI: 4.4 +/- 2.5 and 8.4 +/- 6.1 ms/mm Hg (p=0.03); BRS-RI < or = 3 ms/mm Hg: 8/15 and 2/16 (p=0.02); SDNN: 23.0 +/- 18.0 and 20.0 +/- 11.6 ms (p=0.99); rMSSD: 70.9 +/- 69.8 and 34.1 +/- 30.2 ms (p=0.34); pNN50: 10.7 +/- 14.6 and 4.4 +/- 9.0% (p=0.7); LF: 204.5 +/- 509.7 and 160.7 +/- 265.8 ms2 (p=0.95); LF (NU): 0.5 +/- 0.4 and 0.5 +/- 0.3 (NU) (p=0.77); LF/HF: 1.3 +/- 1.2 and 2.1 +/- 2.2 (p=0.49); LVEF: 32.5 +/- 9.1 and 39.8 +/- 13.3% (p=0.03); LP: 19/24 and 15/19 (p=0.99). The only indices of prognostic values were Robbe-index and LVEF. Their prognostic value in prediction of arrhythmic event occurrence was independent of each other's and of age, time elapsed from MI and number of MI (p=0.007). Non-diagnostic values of BRS-RI were found in 22 patients (42%). CONCLUSIONS: Among the evaluated indices, only LVEF and Robbe-index have prognostic value in prediction of life-threatening ventricular arrhythmia recurrence after myocardial infarction. However, a high percentage of non-diagnostic values obtained in BRS-RI assessment limits the usefulness of this index.

[Electrical remodeling in a patient with biventricular pacemaker]. / Remodeling elektryczny u leczonego stymulacja dwukomorowa.

Electrical remodelling in a patient with biventricular pacemaker - a case report. A case of a 70-year-old patient with dilated cardiomyopathy is presented. The patient underwent biventricular pacemaker implantation and improved markedly. Indications for resynchronisation therapy are discussed.

[Remodeling of coronary arteries examined by arteries intravascular ultrasonography]. / Remodeling tetnic wiencowych badany za pomoca ultrasonografii wewnatrznaczyniowej.

UNLABELLED: In most papers atherosclerotic remodelling was assessed in one segment of each studied artery. Such mode of study makes impossible to investigate the homogeneity of the remodelling. The aim of the study was intravital assessment by means of intravascular ultrasonography (IVUS) of the incidence of positive and negative remodelling in coronary artery segments and verification of the hypothesis that remodelling is inhomogeneous within the same artery. METHOD: Remodelling was assessed quantitatively by IVUS (3.5 F; 20 MHz Visions Five-64 F/X catheters, Oracle In-Vision Imaging System, Endosonics Corp. USA) in 48 segments of 27 coronary arteries. On the base of the difference between total vessel area (TA) at lesion site and reference cross-section (plaque area < 35%) remodelling was classified as negative, positive or absent. In 13 arteries out of 27 studied arteries more than 1 segment was assessed, containing both cross-section with > 50% stenosis and reference cross-section. RESULTS: Positive, negative and absent remodelling was observed in 54%, 29% and 17% of segments, respectively. The analysis revealed two different types of remodelling in 7 out of 13 arteries with several analysed segments. This finding demonstrates that remodelling is inhomogenous within the artery (p < 0.006). CONCLUSIONS: Compensatory enlargement is the most common response of coronary arteries to atherosclerotic plaque development followed by negative remodelling and absence of remodelling. Not homogenous remodelling within the same artery suggests a prominent role of local factors in determining the type of response of the artery to plaque accumulation.

Left ventricle systolic volume in vasovagal syncope patients.

One of the hypotheses put forward concerning the mechanism of vasovagal syncope is that the vagal afferent fibres are activated during vigorous contractions against a partly empty left ventricle. The aim of the study was to confirm this hypothesis by using 2D echocardiography during a head-up tilt test. The study was carried out on 39 patients (17 male, 22 female, age range 21-64 years), all with a history of recurrent syncope. The patients were examined using a 2D echo to measure the end-diastolic and end-systolic volume before the head-up tilt test after the Westminster protocol (45 min/60 grade) and every five minutes after tilting. T patients during head-up tilt test had a positive response and 32 proved negative. A reduction of both the end-diastolic and end-systolic volumes of the left ventricle was noticed. There was no significant difference in the degree of ejection fraction reduction. The difference in ejection fraction reduction between the two groups was similarly non-significant. It was also noticed that the patients with a positive response had more vigorous contractions than those with a negative test. The decision was therefore taken to use a different parameter for the left ventricle contraction, namely the LV posterior wall slope. As this parameter is partly dependent on time, its use in confirming the extremely vigorous nature of the contractions was considered appropriate. Only 6 patients were tested using this parameter. A tendency towards greater left ventricle posterior wall slope values, both before and during tilting was noticed in the group of patients with vasovagal reaction. Our data shows that vigorous contraction is probably less responsible for vasovagal syncope release than left ventricle volume reduction.

Hemodynamic effects of alternative atrial pacing sites in patients with paroxysmal atrial fibrillation.

Recently, multisite atrial pacing has been suggested as an alternative therapy to prevent recurrences of paroxysmal atrial fibrillation (PAF). A study was conducted to compare the acute effects of biatrial (BiA), left atrial (LA), and right atrial appendage (RAA) pacing on cardiac hemodynamics. In 14 patients with PAF and a BiA pacemaker (with leads in the RAA and coronary sinus), cardiac output (CO), right (RV) and left ventricular (LV) filling, RA-LA contraction delay [PA(m-t)] and the difference in A wave duration [Adif(m-p)] at the level of the mitral valve (Adurm) and pulmonary veins (Adurp) during RAA, BiA, and LA pacing were examined by echo-Doppler measurements. The atrial pacing site did not affect the CO. LA, but not BiA, pacing resulted in delayed RA contraction in comparison with RAA pacing with significant diminution of the RA contribution to RV filling. With LA pacing, the usual right-to-left atrial contraction sequence was reversed (PA(m-t): 8 +/- 7 ms control; 5 +/- 30 ms RAA; -10 +/- 21 ms BiA; -72 +/- 36 ms LA; LA versus control versus RAA and versus BiA, P < 0.001. LA and BiA pacing prolonged Adurp (LA 186 +/- 52 ms, BiA 180 +/- 45 ms, RAA 153 +/- 49 ms; LA and BiA vs RAA, P < 0.01). Thus Adurp exceeded Adurm [Adif (m-p): control 38 +/- 40 ms, RAA 7 +/- 42 ms, BiA -12 +/- 43 ms, LA -20 +/- 44 ms; control vs RAA, BiA, and LA; and RAA vs LA, P < 0.05]. The study showed that (1) the atrial pacing site has no influence on global cardiac performance; (2) the hemodynamic effect of BiA pacing is not superior to that of RAA pacing, and LA pacing can even be deleterious; (3) LA pacing reverses the usual right-to-left atrial contraction sequence and reduces the RA contribution to RV filling; (4) BiA and LA pacing prolong Adurp due to an altered activation pattern, decreased pulmonary venous return, or increased LA pressure.