Heart rate and blood pressure variability in patients implanted with rate-responsive pacemaker.

Rate-responsive pacemakers (PMs) aim at having pacing rates as similar to physiological cardiac rhythms as possible. The pacemaker INOS(2+)-CLS (Biotronik, Germany) implements a closed loop strategy (CLS) based on indirect measures of right ventricle contractility using intracardiac impedance signal. The contractility is, in turn, related to the autonomic nervous system control to the heart. Aim of this study was to evaluate the 24h beat-to-beat heart rate and blood pressure profiles in patients implanted with CLS rate adaptive PM. 24h ECG and arterial pressure waveform acquisition were performed by a digital Holter system by the Portapres equipment, respectively. A proper-designed algorithm was developed to classify PM pacing modalities. For each beat we estimated the heart rate (HR), and the systolic and diastolic pressure values (SP, DP). So far, 6 patients have been studied: 4 patients have been analyzed both with and without rate responsive modalities (DDD-R and DDD, respectively); 2 patients have been studied only with rate-responsive modality. Results obtained in 6 patients show that this rate adaptive PM accurately preserve the heart rate and blood pressure variability throughout the 24h. In particular, the rate adaptation of PM based on impedance measurements succeeds in maintaining the spontaneous HR, SP and DP on a beat-to-beat basis.

Impact of Closed-Loop Stimulation, overdrive pacing, DDDR pacing mode on atrial tachyarrhythmia burden in Brady-Tachy Syndrome. A randomized study.

AIMS: Atrial overdrive pacing algorithms increase Atrial Pacing Percentage (APP) to reduce Atrial Tachyarrhythmia (AT) recurrences in patients with Brady-Tachy Syndrome (BTS). This study aimed to compare AT burden and APP in BTS patients treated with conventional DDDR pacing, DDD+ overdrive or Closed-Loop Stimulation (CLS). METHODS AND RESULTS: One hundred and forty-nine BTS patients were included (72 male, mean age 74+/-9), who received a dual chamber pacemaker (Philos DR or Inos 2+CLS, Biotronik GmbH, Berlin, Germany) programmed in DDD at 70min(-1). At 1-month follow-up, DDDR, DDD+ or CLS algorithms were activated according to randomization. Follow-up visits for data collection were performed at 4 and 7 months. Non parametric statistical tests (Kruskal-Wallis H-test, Dunn test, Spearman coefficient) were used to analyse not-normally-distributed samples. At 7 months, AT burden was significantly lower in CLS group (20.3+/-63.1min/day, P<0.01) compared to DDDR (56.0+/-184.0min/day) and DDD+ group (63.1+/-113.8min/day). APP was higher in CLS (89.0+/-13.2%) and in DDD+ group (97.9+/-2.7%) than in DDDR group (71.1+/-26.7%, P<0.001). The correlation found between AT burden and APP was very weak: at 7-month follow-up the Spearman coefficient was -0.29 (P=NS) in CLS, -0.52 (P<0.01) in DDD+, -0.22 (P=NS) in DDDR. CONCLUSIONS: CLS pacing was associated with a significantly lower AT burden,compared to the other pacing algorithms. Moreover APP was significantly higher in DDD+ and in CLS mode, than in DDDR. APP weakly correlated with AT burden only in DDD+ mode, though the lowest AT burden level was obtained in the CLS group where no significant correlation was found.

Electrocardiographic pattern of Brugada syndrome disclosed by a febrile illness: clinical and therapeutic implications.

BACKGROUND: Recent studies have identified a direct link between the ionic mechanisms responsible for the electrocardiographic (ECG) pattern of the Brugada syndrome (BS) and the in vitro experimental temperature, pointing to the possibility that some BS patients may display the ECG phenotype only during a febrile state, being in this setting at risk of lethal arrhythmias. CASE REPORT: A 53-year-old man referred to the emergency room for abdominal pain and fever. The ECG showed dome-shaped ST-segment elevation in V1-V3, as in the typical BS. The personal and family history were unremarkable for syncope and sudden death and physical, laboratory and ultrasound examinations were negative. On day 3, at normal body temperature, the patient's ECG returned to normal and the ECG abnormalities were later reproduced with intravenous flecainide. The patient refused the implantation of a loop recorder and was discharged after 6 days. He has remained asymptomatic during 2 years of follow-up. CONCLUSIONS: The typical ECG phenotype of BS disclosed by a febrile illness confirms the in vitro experimental data that previously established a correlation between ECG pattern of BS and temperature variations. The clinical and therapeutic implications of these findings are discussed.

Recovery of contractility of viable myocardium during inotropic stimulation is not dependent on an increase of myocardial blood flow in the absence of collateral filling.

OBJECTIVES: The purpose of this study was to determine whether contractile recovery induced by dobutamine in dysfunctioning viable myocardium supplied by nearly occluded vessels is related to an increase in blood flow in the absence of collaterals. BACKGROUND: Dobutamine is used to improve contractility in ventricular dysfunction during acute myocardial infarction. However, it is unclear whether a significant increase in regional blood flow may be involved in dobutamine effect. METHODS: Twenty patients with 5- to 10-day old anterior infarction and > or =90% left anterior descending coronary artery stenosis underwent 99mTc-Sestamibi tomography (to assess myocardial perfusion) at rest and during low dose (5 to 10 microg/kg/min) dobutamine echocardiography. Rest echocardiography and scintigraphy were repeated >1 month after revascularization. Nine patients had collaterals to the infarcted territory (group A), and 11 did not (group B). RESULTS: Baseline wall motion score was similar in both groups (score 15.9+/-1.3 vs. 17.4+/-2.0, p = NS), whereas significant changes at dobutamine and postrevascularization studies were detected (F[2,30] = 409.79, p < 0.0001). Wall motion score improved significantly (p < 0.001) in group A both at dobutamine (-5.3+/-2.2) and at postrevascularization study (-5.5+/-1.9), as well as in group B (-3.9+/-2.8 and -4.5+/-2.4, respectively). Baseline 99mTc-Sestamibi uptake was similar in both groups (62.9+/-9.7% vs. 60.3+/-10.4%, p = NS), whereas at dobutamine and postrevascularization studies a significant change (F[2,30] = 65.17, p < 0.0001) and interaction between the two groups (F[2,30] = 33.14, p < 0.0001) were present. Tracer uptake increased significantly in group A both at dobutamine (+ 10.9+/-7.9%, p < 0.001) and at postrevascularization study (12.1+/-8.7%, p < 0.001). Conversely, group B patients showed no change in tracer uptake after dobutamine test (-0.4+/-5.8, p = NS), but only after revascularization (+8.8+/-7.2%, p < 0.001). CONCLUSIONS: The increase in contractility induced by low dose dobutamine infusion in dysfunctional viable myocardium supplied by nearly occluded vessels occurs even in the absence of a significant increase in blood flow.

Recognizing and managing permanent junctional reciprocating tachycardia in the catheter ablation era.

There is general agreement that an orthodromic AV reentry using a concealed slow conducting accessory pathway as the retrograde limb of the circuit constitutes the underlying mechanism of the permanent form of junctional reciprocating tachycardia (PJRT). In this arrhythmia, the standard ECG typically shows a "long R-P' tachycardia" with retrograde P wave negative in the inferior leads. A careful electrophysiologic evaluation is necessary to confirm the diagnosis of PJRT. Recent reports have demonstrated that the radiofrequency current catheter technique provides a safe and highly effective therapeutic tool for patients suffering from this arrhythmia.

Iatrogenic pneumohemomediastinum mimicking cardiac tamponade: a complication of catheter ablation procedure.

We describe a patient who developed cardiac tamponade during electrophysiological mapping aimed at ablating an atrioventricular accessory pathway. Transesophageal echocardiography showed compression of the left pulmonary veins due to pneumohemomediastinum secondary to left subclavian vein cannulation.

Permanent mechanical catheter ablation of an accessory pathway in a child.

Permanent mechanical ablation of an accessory atrioventricular pathway was observed in an infant during intracavitary electrophysiological mapping. The persistent lack of preexcitation was confirmed during a 15-month follow-up period.

Coronary air embolism complicating accessory pathway catheter ablation: detection by echocardiography.

Percutaneous radiofrequency catheter ablation has been recently introduced for treatment of Wolff-Parkinson-White syndrome. Access to left free-wall atrioventricular accessory pathways can be obtained either via retrograde cardiac catheterization or via the transseptal procedure, which allows ablation of the accessory pathway at its ventricular or atrial insertion, respectively. We describe a patient with Wolff-Parkinson-White syndrome in whom coronary air embolism occurred as a complication of transseptal percutaneous radiofrequency catheter ablation. The diagnosis was made by two-dimensional echocardiography showing a marked echocontrast effect in the posterior wall and in the posterior half of the interventricular septum. A grossly evident breakage of the rubber seal of the vascular sheath was supposed to be the cause of air insinuation. This report suggests that the transseptal approach should be used with caution in performing percutaneous radiofrequency catheter ablation to avoid the risk of air embolization. Two-dimensional echocardiography is an ideal tool to detect this complication.

[Non-pharmacological treatment of arrhythmia]. / Terapia non farmacologica delle aritmie.

During the past decade, a variety of innovative procedures and devices for non-pharmacological treatment of tachyarrhythmias have been proposed. Recent improvements in the implantable cardioverter/defibrillators and transcatheter ablative techniques have resulted in a revolution of the therapeutic approach in ventricular and supraventricular tachyarrhythmias, respectively, providing a valuable alternative to conventional antiarrhythmic surgery. Indeed, the selection criteria for surgery for tachyarrhythmias have been revised, and this therapeutic option is considered appropriate only for selected patients with postinfarction ventricular tachycardia. Ther implantable cardioverter/defibrillator has proved effective in conversion of life-threatening tachyarrhythmias, leading a dramatic decrease in the incidence of sudden death in high risk subjects. Thus, with further refinements, a wide use of this therapeutic modality can be anticipated. Transcatheter ablation has become the first-line option in the most common forms of supraventricular tachycardias, such as accessory pathway-mediated tachycardia and AV nodal reentry. More recently, encouraging results of this technique in common atrial flutter and ectopic atrial tachycardia have been reported, although confirmation with larger series and longer follow-up is needed. In general, results of catheter ablation in ventricular tachycardia have been disappointing, with the exception of bundle branch reentry and idiopathic ventricular tachycardia, in which a high success rate is reported. An increasingly important role of these therapeutic modalities is expected. In the meanwhile, due to their evolutional character and the specific competence required for their use, such procedures should be performed exclusively in well trained centers.

Curative radiofrequency catheter ablation for permanent junctional reciprocating tachycardia.

Two patients with the permanent form of junctional reciprocating tachycardia successfully treated with the radiofrequency catheter ablation technique are described. In both patients a reentrant tachycardia utilizing a concealed slow conducting posterior septal accessory pathway for retrograde conduction was demonstrated. Radiofrequency current was delivered below the coronary sinus orifice. The procedure resulted in ablation of the accessory pathway conduction in both patients. During the follow-up, both patients remained free from tachycardia on no medication. This report demonstrates that the arrhythmogenic substrate of the permanent junctional reciprocating tachycardia can be easily suppressed by means of the radiofrequency catheter technique.

Resting and ambulatory ECG predictors of mode of death in dilated cardiomyopathy.

With the purpose of verifying whether the electrocardiogram (ECG) pattern alone can predict the mode of death in dilated cardiomyopathy, data from 12-lead ECGs and 48-hour arrhythmia monitoring were evaluated in 67 patients with dilated cardiomyopathy. During a mean follow-up period of 3 +/- 2 years, death from congestive heart failure occurred in 18 patients (27%), whereas 10 (15%) died suddenly (NS). Multivariate analysis showed that left bundle branch block (p < 0.001) and left atrial enlargement (p < 0.001) were independently related to death from congestive heart failure. Ventricular arrhythmias of Lown grade 4A or 4B (p < 0.001) and repolarization time, as assessed by QTc-QRS interval (p < 0.05), were independent predictors of sudden death. It is concluded that ECG features alone may be helpful for risk factor characterization of dilated cardiomyopathy patients, provided that multiple ECG criteria are utilized at time of diagnosis.

Transcatheter ablation of the accessory pathway in 2 patients with life-threatening tachyarrhythmias.

Successful transcatheter ablation of an accessory pathway in 2 patients with life-threatening tachyarrhythmias is reported. In both cases, electrophysiological evaluation documented the posterior septal location of the anomalous atrioventricular connection. Radiofrequency current energy was delivered just below the coronary sinus orifice, and resulted in disappearance of preexcitation. During the follow-up, both patients remained free from tachyarrhythmias on no medication, and serial electrocardiographic recordings confirmed the persistent absence of preexcitation. It is concluded that ablation of accessory pathways can be accomplished easily and without risk by means of the radiofrequency catheter technique. This therapeutic modality requires a short hospitalization and can be recommended as the first option in patients with the Wolff-Parkinson-White syndrome.