Leadless Pacemakers: Current Achievements and Future Perspectives.

Despite the technological advances in pacemaker technology, the transvenous implanted leads are still considered the Achilles' heel of this rhythm-control therapy. The leadless permanent pacemaker system was developed as an option to bypass the weakness of the transvenous approach. Advances in battery technology and deep miniaturisation of electronics now offer the opportunity to implant the whole pacemaker system into the right ventricle. This review aims to provide a comprehensive report on the advent of leadless pacemakers, their clinical usefulness and the future perspectives of this disruptive and promising technology. Further research is required before some of these technologies are safely and routinely used in clinical practice.

Electro-Mechanical Alterations in Atrial Fibrillation: Structural, Electrical, and Functional Correlates.

Atrial fibrillation is the most common arrhythmia encountered in clinical practice affecting both patients' survival and well-being. Apart from aging, many cardiovascular risk factors may cause structural remodeling of the atrial myocardium leading to atrial fibrillation development. Structural remodelling refers to the development of atrial fibrosis, as well as to alterations in atrial size and cellular ultrastructure. The latter includes myolysis, the development of glycogen accumulation, altered Connexin expression, subcellular changes, and sinus rhythm alterations. The structural remodeling of the atrial myocardium is commonly associated with the presence of interatrial block. On the other hand, prolongation of the interatrial conduction time is encountered when atrial pressure is acutely increased. Electrical correlates of conduction disturbances include alterations in P wave parameters, such as partial or advanced interatrial block, alterations in P wave axis, voltage, area, morphology, or abnormal electrophysiological characteristics, such as alterations in bipolar or unipolar voltage mapping, electrogram fractionation, endo-epicardial asynchrony of the atrial wall, or slower cardiac conduction velocity. Functional correlates of conduction disturbances may incorporate alterations in left atrial diameter, volume, or strain. Echocardiography or cardiac magnetic resonance imaging (MRI) is commonly used to assess these parameters. Finally, the echocardiography-derived total atrial conduction time (PA-TDI duration) may reflect both atrial electrical and structural alterations.

Transvenous extraction of cardiac rhythm device leads: a report of the experience from a single referral centre in Greece.

INTRODUCTION: As rates of implanted cardiac electronic devices continue to rise, lead extraction procedures are crucial for the management of complications. The optimal method for such procedures has been constantly debated. We sought to review our experience of lead extraction using a conventional technique. METHODS: This was a retrospective study of lead extraction procedures in a major referral centre in Greece. Leads were extracted in a series of 66 consecutive patients (69% men, age range 53-90 years) who visited our centre between August 2008 and June 2012. The extraction procedure was performed in the catheterization lab with a widely used system composed of a locking stylet and sheath. RESULTS: A total of 120 leads were extracted (51 atrial, 69 ventricular) including 19 defibrillator leads and 9 coronary sinus leads. The most frequent indication for lead extraction was infective endocarditis (28 patients, 42%), followed by generator pocket infection (22 patients, 33%), and lead malfunction (16 patients, 24%). Extraction was achieved through the venous entry-site approach in all procedures. The leads were completely extracted in 65 patients (98.5%). Only one complication was recorded: perforation of the right atrium in one patient (1.5%), who eventually underwent emergency cardiac surgery with a good outcome. CONCLUSIONS: Our data confirm that a conventional mechanical technique is highly effective for successful extraction of all types of implanted cardiac electronic device leads and is associated with very limited complications.

Primary prevention of sudden cardiac death in a nonischemic dilated cardiomyopathy population: reappraisal of the role of programmed ventricular stimulation.

BACKGROUND: We considered the role of programmed ventricular stimulation in primary prevention of sudden cardiac death in an idiopathic dilated cardiomyopathy population. METHODS AND RESULTS: One hundred fifty-eight patients with idiopathic dilated cardiomyopathy underwent programmed ventricular stimulation. Ventricular tachycardia/ventricular fibrillation was triggered in 44 patients (group I, 27.8%) versus 114 patients (group II), where ventricular tachycardia/ventricular fibrillation was not induced. Sixty-nine patients with idiopathic dilated cardiomyopathy underwent implantable cardioverter-defibrillator (ICD) implantation: 41/44 in group I and 28/114 in group II. The major end points of the study were overall mortality and appropriate ICD activation. Overall mortality during the 46.9 months of mean follow-up was not significantly different between the 2 groups. Patients with left ventricular ejection fraction ≤35% (n=119) demonstrated a higher overall mortality rate compared with the patients with left ventricular ejection fraction >35% (n=39; 16.8% versus 10.3%, log-rank P=0.025). Advanced New York Heart Association class (III and IV versus I and II) was the single independent and strongest prognostic factor of overall mortality (hazard ratio, 11.909; P<0.001; confidence interval, 3.106-45.65), as well as of cardiac mortality (hazard ratio, 14.787; P=0.001; confidence interval, 2.958-73.922). Among ICD recipients, ICD activation rate was significantly higher in group I compared with group II (30 of 41 patients-73.2% versus 5 of 28 patients-17.9%; log-rank P=0.001), either in the form of antitachycardia pacing (68.3% versus 17.9%; log-rank P=0.001) or in the shock delivery form (51.2% versus 17.9%; log-rank P=0.05). Induction of ventricular tachycardia/ventricular fibrillation during programmed ventricular stimulation in contrast to left ventricular ejection fraction was the single independent prognostic factor for future ICD activation (hazard ratio, 4.195; P=0.007; confidence interval, 1.467-11.994). CONCLUSIONS: Inducibility of ventricular tachycardia/ventricular fibrillation was associated with an increased likelihood of subsequent ICD activation and sudden cardiac death surrogate.

Arrhythmogenic right ventricular cardiomyopathy: the challenge of genetic interpretation in clinically suspected cases.

This is the case of a 43-year-old Caucasian man with frequent episodes of paroxysmal atrial fibrillation (AF) and normal resting electrocardiogram (ECG), who fulfilled two minor diagnostic criteria for arrhythmogenic right ventricular cardiomyopathy (ARVC): late potentials by signal-averaged ECG and regional right ventricular outflow tract (RVOT) dyskinesia with mildly dilated RVOT end-diastolic diameter. Genetic test results revealed a disease-associated missense mutation in DSC2 (p.E102K), adding a major diagnostic criterion according to recently published modified Task Force Criteria. However, 2 years after successful ablative therapy for AF, the patient remains completely asymptomatic, without any clinical signs of ARVC. Both ventricular and supraventricular arrhythmias had vanished after AF ablation. Our patient mainly suffered AF without significant ventricular arrhythmias, a very uncommon clinical presentation of ARVC.

Continuity equation is the echocardiographic method of choice to assess degenerative mitral stenosis.

We present a rare case of a patient with severe, symptomatic degenerative calcific mitral stenosis (MS). Calcification of mitral valve annulus (MVA) is a frequent finding in elderly patients. It can be isolated or associated more often with mitral valve insufficiency than MS. In rare cases, it results in severe MS. An accurate measurement of MVA in degenerative calcific MS is problematic because the limiting orifice is near the annulus and not at the leaflet tips as in rheumatic MS. Continuity equation is the best echocardiographic method to assess the MVA in degenerative MS, correlating well with invasive methods. Real-time three-dimensional echocardiography is a promising tool and provides an accurate measurement of MVA in calcific MS, with a very good correlation compared to continuity equation. On the other hand, the use of pressure half-time is often inaccurate and should be avoided, while two-dimensional planimetry is difficult and not reliable in degenerative MS. The values of mean gradient and systolic pulmonary artery pressure depend on several factors and should be only supportive signs and should not be considered as surrogate markers of the severity of MS.

Specific electrocardiographic features associated with Cushing's disease.

OBJECTIVE: Hypercortisolaemia is associated with an increased risk of cardiovascular disease (CVD), either through a direct action on the myocardium or by increased traditional cardiovascular risk factors. The aim of this study was to investigate whether the alterations in the ECG in Cushing's disease (CD) are predictable from risk factor analysis alone. DESIGN: In 79 patients with a diagnosis of CD, retrospectively recruited, ECG features [corrected for heart rate QT (QTc), QTc dispersion (QTcd), left ventricular hypertrophy (ECG-LVH), right ventricular hypertrophy (ECG-RVH)], systolic (SBP) and diastolic (DBP) blood pressure were assessed. Biochemical, hormonal (cortisol at 09·00 h or cortisol day curve, CDC) and carbohydrate abnormalities (CHA), history of hypertension and cardiovascular disease were recorded. For comparison reasons, a group of 42 healthy subjects matched for gender, age and body mass index previously subjected to ECG assessment were selected. RESULTS: In patients with CD, we noted the following prevalence: metabolic syndrome 39%, hypertension 81%, CVD 21·5%, hypercholesterolaemia 37%, hypertriglyceridaemia 29%, CHA 41%, but a history of cardiac dysrhythmia was only noted in a single patient. No difference in QTc or QTcd was shown between patients with normal or low potassium levels. QTcd >50 ms was associated with both increased ECG-LVH and ECG-RVH. When compared to the control group, patients had longer QTcd (P < 0·001), more prevalent LVH (P < 0·001) and RVH (P = 0·001), and higher SBP and DBP (P < 0·001), but similar QTc. Both CD and ECG evidence of LVH predicted prolonged QTcd, but the association of CD with a prolonged QTcd was independent of other risk factors, including hypertension. CONCLUSIONS: Prolonged QTcd in association with ECG evidence of LVH appears to be the specific feature of CD. This may be relevant in the choice of medical therapy for CD and for consideration of treatment of the comorbidities that are associated with hypercortisolaemia.

Mechanistic insights into arrhythmogenic right ventricular cardiomyopathy caused by desmocollin-2 mutations.

AIMS: Recent immunohistochemical studies observed the loss of plakoglobin (PG) from the intercalated disc (ID) as a hallmark of arrhythmogenic right ventricular cardiomyopathy (ARVC), suggesting a final common pathway for this disease. However, the underlying molecular processes are poorly understood. METHODS AND RESULTS: We have identified novel mutations in the desmosomal cadherin desmocollin 2 (DSC2 R203C, L229X, T275M, and G371fsX378). The two missense mutations (DSC2 R203C and T275M) have been functionally characterized, together with a previously reported frameshift variant (DSC2 A897fsX900), to examine their pathogenic potential towards PG's functions at the ID. The three mutant proteins were transiently expressed in various cellular systems and assayed for expression, processing, localization, and binding to other desmosomal components in comparison to wild-type DSC2a protein. The two missense mutations showed defects in proteolytic cleavage, a process which is required for the functional activation of mature cadherins. In both cases, this is thought to cause a reduction of functional DSC2 at the desmosomes in cardiac cells. In contrast, the frameshift variant was incorporated into cardiac desmosomes; however, it showed reduced binding to PG. CONCLUSION: Despite different modes of action, for all three variants, the reduced ability to provide a ligand for PG at the desmosomes was observed. This is in agreement with the reduced intensity of PG at these structures observed in ARVC patients.