Mechanisms involved in symptomatic myocardial bridging

Background.In patients with extensive myocardial bridging, evaluation of its clinical significance remains a challenge. Hypothesis.Sequential invasive testing is feasible and gives more insight into the pathophysiological mechanism of bridging-related angina. Methods.Twelve patients with chest pain, proven ischaemia and extensive myocardial bridging were assessed. Myocardial bridging was evaluated at rest, during intracoronary acetylcholine infusion, through coronary flow velocity and flow reserve measurements, and during dobutamine stress. Results.The mean length of the bridging segment was 24.9 mm (QCA; range 8.4-48.0 mm). Acetylcholine infusion caused severe vasospasm in two patients. In these two patients anginal symptoms were related to vasospasm and sequential testing was discontinued. In the remaining ten patients sequential testing was continued. Coronary flow reserve was normal in all patients: 3.3±0.6. In six patients reliable quantitative measurements could be performed during dobutamine stress. The mean systolic diameter of the bridging segment was 1.6±0.4 at baseline and 1.3±0.3 during dobutamine stress (mean of differences 0.38 (95% CI 0.1-0.7)). The difference between the diastolic and systolic diameter in the bridging segment increased from 0.3±0.2 mm at baseline to 1.0±0.5 mm during dobutamine infusion (mean of differences 0.6 (95% CI 0.3 to 0.9)). Conclusion.Sequential testing for bridging is feasible and may disclose endothelial dysfunction or spasm as an underlying mechanism in a minority of patients. Coronary flow reserve was preserved. Dobutamine stress unmasked further lumen reduction and may give further insight into the clinical significance of myocardial bridging in individual patients. (Neth Heart J 2008;16:10-5.)     

Evaluation of global left ventricular function assessment of non-fluorescent electromechanical endocardial mapping compared with biplane left ventricular contrast angiography

Background. Little is known about the diagnostic accuracy of global LV function assessment by electromechanical endocardial mapping (EEM). The aim of the present study was to determine the relationship between global left ventricular (LV) function measured by EEM and biplane left ventricular contrast angiography (LVA) after ST-elevation myocardial infarction (STEMI). Methods. Thirty-seven patients underwent LVA and EEM during routine coronary angiography four months after primary percutaneous intervention for STEMI. Global LV function parameters were available from both techniques in all patients. LVA was regarded as reference standard. Results. All procedures were carried out without adverse events. Average age was 55±10 years and 84% were male. EEM showed an overestimation of end-diastolic volume (EDV) and end-systolic volume (ESV) of 6.5 ml and 25.5 ml, respectively. Correlation (r) was 0.84 (p<0.001) for EDV and 0.74 (p<0.001) for ESV. Average left ventricular ejection fraction (LVEF) measured by EEM was 17.2% point (±11.3% point) lower compared with LVA (r=0.69, p<0.001). Conclusion. Although global functional parameters by EEM correlated well with LVA, the relatively large differences in terms of absolute values for ventricular volumes and LVEF render the two techniques non-interchangeable for global LV-function-data. (Neth Heart J 2010;18:72–77.)     

Usefulness of remote magnetic navigation for ablation of ventricular arrhythmias originating from outflow regions

Monomorphic ventricular tachycardia (VT) and symptomatic monomorphic PVCs originating from the region of the right and left outflow tracts are increasingly treated by radiofrequency (RF) catheter ablation. Technical difficulties in catheter manipulation to access these outflow tract areas, very accurate mapping and reliable catheter stability are key issues for a successful treatment in this vulnerable region. VT ablation from the aortic sinus cusp (ASC) in particular carries a significant risk of perforation, of creating left coronary artery injury and of damage to the aorta and the aortic valve. This case series describes RF ablation of VT originating in the outflow region using the remote magnetic navigation system (MNS). Potential advantages of the MNS are catheter flexibility, steering accuracy and reproducibility to navigate to a desired location with a low probability of perforating the myocardium. This report supports the idea of using advanced MNS technology during RF ablation in regions which are difficult to reach and thin walled, such as parts of the outflow tract and the ASC. (Neth Heart J 2009;17:245–9.)     

Managing low profile - left main transmural laceration

Perforation of the left main stem is a rare complication associated with combined aortic valve replacement and by-pass surgery. One-year following aortic valve replacement a 70-year-old male presented with chest pain. This was related to a slowly expanding haematoma caused by a low profile chronic perforation of the left main. Subsequently, a tailored percutaneous modification of the main stem was performed. At three months follow-up, he had no complaints and selective coronary angiography confirmed the successful sealing of the perforation with a concomitant regression of the prior haematoma.     

How to target uncertainty in Dutch invasive cardiovascular care

Current meetings of the Netherlands Society of Cardiology and the Working Group on Intervention Cardiology have shown that new strategic developments in the Dutch healthcare system have created much turbulence and uncertainty amongst members of the organisations. Both on-site and off-site new cardiac centres with and without surgical backup, respectively, are arising or being planned throughout the Netherlands. These strategic adaptations are related to service delivery failure, despite appropriate quality measures. To understand the reasoning behind this uncertainty and how to deal with it, we need to explore its origin and thinking. Its rationale is based on the assumption that each organisation relies on its ability to survive through innovation and transformation. Cardiologists and cardiac surgeons are key players in a large group of stakeholders participating in the chain of cardiovascular care. In addition, the Dutch healthcare system is deeply embedded in a historical sociopolitical environment. This may explain why ongoing uncertainty may beget more uncertainty. What are the consequences for the content of the route forward?     

Fast and slow narrow complex tachycardia in one patient: two of a kind?

A 35-year-old female was referred to our hospital. For more than ten years, she had had complaints of two types of paroxysmal palpitations, both with a sudden onset. The first type was rapid and often accompanied by light-headedness; the second she described as much less rapid, better tolerated, and often terminated by the Valsalva manoeuvre. The incidence and duration of both types of paroxysms were increasing. In the emergency room of the referring hospital, the tachycardia was terminated with intravenous verapamil.The electrophysiological study revealed normal conduction parameters. Premature atrial beats (due to catheter manipulation) or delivered atrial extra stimuli over a wide range easily induced two types of tachycardia.AV node modification by radiofrequency ablation using the posterior approach was performed. With this approach, RF ablation of the caudal extension of the AV node is performed, which modifies the slow pathway, so that the reentrant circuit is interrupted. After this intervention, no tachycardia whatsoever could be induced and during followup (8 months), no recurrent arrhythmia of any kind occurred.