The future of interventional therapy in cardiology

This satellite symposium was organised and sponsored by Siemens AG Medical Solutions and chaired by P.J. de Feyter (Rotterdam, the Netherlands) and D.J. Pennell (London, UK). The purpose of this symposium was to discuss the current status and the future directions in interventional cardiology, with particular emphasis on the role of imaging in performing interventional procedures.     

Congenital diverticulum of the left atrium

Two cases of congenital diverticulum of the left atrial appendage are described. The first patient was a 3-year-old girl who had a cerebral embolism. The second patient was a 3(1/2)-year-old girl with signs of pericarditis. Treatment consisted of excising the diverticula. The limited literature on diverticulum of the left atrium as a congenital abnormality is also briefly reviewed.     

Review of skin dose calculation software in interventional cardiology

PurposeIn interventional cardiology, patients may be exposed to high doses to the skin resulting in skin burns following single or multiple procedures. Reviewing and analysing available software (online or offline) may help medical physicists assessing the maximum skin dose to the patient together with the dose distribution during (or after) these procedures.Method and resultsCapabilities and accuracy of available software were analysed through an extensive bibliography search and contacts with both vendor and authors. Their markedly differed among developers.In total, 22 software were identified and reviewed according to their algorithms and their capabilities. Special attention was dedicated to their main features and limitations of interest for the intended clinical use.While the accuracy of the 12 software products validated with measurements on phantoms was acceptable (within ± 25%), the agreement was poor for the two products validated on patients (within ± 43% and ± 76%, respectively). In addition, no software has been validated on angiographic units from all manufacturers, though several software developers claimed vendor-independent transportability. Only one software allows for multiple procedures dose calculation.ConclusionLarge differences among vendors made it clear that work remains to be done before an accurate and reliable skin dose mapping is available for all patients.     

Establishing the European diagnostic reference levels for interventional cardiology

Interventional cardiac procedures may be associated with high patient doses and therefore require special attention to protect the patients from radiation injuries such as skin erythema, cardiovascular tissue reactions or radiation-induced cancer. In this study, patient exposure data is collected from 13 countries (37 clinics and nearly 50 interventional rooms) and for 10 different procedures. Dose data was collected from a total of 14,922 interventional cardiology procedures. Based on these data European diagnostic reference levels (DRL) for air kerma-area product are suggested for coronary angiography (CA, DRL = 35 Gy cm²), percutaneous coronary intervention (PCI, 85 Gy cm²), transcatheter aortic valve implantation (TAVI, 130 Gy cm²), electrophysiological procedures (12 Gy cm²) and pacemaker implantations. Pacemaker implantations were further divided into single-chamber (2.5 Gy cm²) and dual chamber (3.5 Gy cm²) procedures and implantations of cardiac resynchronization therapy pacemaker (18 Gy cm²). Results show that relatively new techniques such as TAVI and treatment of chronic total occlusion (CTO) often produce relatively high doses, and thus emphasises the need for use of an optimization tool such as DRL to assist in reducing patient exposure. The generic DRL presented here facilitate comparison of patient exposure in interventional cardiology.     

Remodeling of the left atrium in pacing-induced atrial cardiomyopathy

Rapid atrial pacing produces atrial systolic and diastolic failure characterized by absent atrial booster pump function, increased atrial chamber stiffness, enhanced atrial conduit function, and atrial enlargement. However, the processes underlying these abnormalities are poorly understood. Therefore, we examined left atrial myocardium from dogs with rapid pacing-induced atrial failure (400 bpm for 6 weeks) and from control dogs. Western blotting was used to determine the levels of proteins involved in calcium homeostasis (SERCA 2A, phospholamban, Na⁺-Ca²⁺ exchanger). Matrix metalloproteinase (MMP) activity was measured using gelatin and casein zymography, and levels of tissue inhibitor of metalloproteinase-4 (TIMP-4) and the TIMP-4 complexed with MMPs were measured with Western blot analysis. There were no differences in SERCA 2A or Na⁺-Ca²⁺ exchanger protein levels, but phospholamban level was significantly decreased in atrial samples from rapidly paced dogs (51.2 ± 7.8 vs. 77.0 ± 10.0, p < 0.01). The activity of MMP-9 was selectively and significantly increased by 50%, and the level of complexed TIMP-4 protein was significantly decreased by 50% in samples from dogs with atrial failure. Thus, rapid pacing-induced atrial failure is associated with differential changes in MMP activity, an unchanged number of calcium pumps, and compensatory changes in the level of phospholamban.     

A fatal free floating thrombus in left atrium

An 81 year old woman, diagnosed with rheumatic mitral valve disease and atrial fibrillation ten years previous, was admitted due to a right carotid transient ischemic attack and a acute coronary syndrome. No ST elevation was noted in the region supplied by the anterior descending artery coronary (troponin T increased and anterolateral negative waves T). In recent years years, she had maintained with (anticoagulants) an INR of 2.5-3.5; however, in the previous month the INR had dropped to 1.8. The transthoracic echocardiography showed an anterolateral hypokinesis and a globular hyperechoic mass of 2 x 4 cm which appeared to be a free floating thrombus in the dilated left atrium. This occasionally caused occlusion of the mitral valve, which itself had a severe rheumatic stenosis of approximately 1 cm2. Due to the high risk of occlusion of the mitral valve and systemic embolisms, the mitral valve replacement and thrombectomy was recommend to the patient. The patient refused this treatment and subsequently died 5 days later. This case emphasizes the importance of a suitable level of anticoagulation (INR between 2,5 and 3,5) in patients with mitral stenosis and chronic atrial fibrillation. These cases have a the high risk of thromboembolism, and urgent surgery is mandatory when a free floating left atrial thrombus is observed.