Complete embolization of a mechanical aortic valve during trail running-a case report with a lucky ending.

Background: Complete embolization of a prosthetic heart valve is extremely rare and dangerous. This case reports a total embolization of a mechanical aortic valve and contributes to the literature regarding the diagnostic challenges related to infective endocarditis and follow-up after valvular surgery. Case summary: A 28-year-old male 11.5 years status-post a mechanical aortic valve replacement presented with acute onset of chest pain and dyspnoea while jogging. The patient lost consciousness and went into cardiopulmonary arrest with acute pulmonary oedema and circulatory shock. An echocardiogram revealed an empty aortic annulus, and a chest radiograph showed an embolized valve in the aortic arch. The patient underwent emergent removal of the embolized valve and replacement with a new mechanical aortic valve. The patient survived with minimal sequelae. At a 3-month follow-up, he had resumed work, and the only sequelae were mild left ventricular dysfunction and minor vision loss. Although he experienced no warning signs or symptoms, the most likely aetiology for embolization of the valvular prosthesis was infective endocarditis, which was revealed by re-evaluation of an echocardiogram recorded 1 month before the presentation which demonstrated a subtle motion abnormality of the valve. Conclusions: We present a case of a late complete embolization of a mechanical aortic valve most likely caused by asymptomatic infective endocarditis. The case illustrates the challenges in follow-up after valvular surgery and highlights the ultimate benefit of a well-functioning pre-hospital to hospital chain.

Reliability and agreement of point-of-care carotid artery examinations by experts using hand-held ultrasound devices in patients with ischaemic stroke or transitory ischaemic attack.

OBJECTIVES: To investigate the reliability and agreement of hand-held ultrasound devices (HUDs) compared with conventional duplex ultrasound (HIGH) in examination for carotid stenosis in patients with suspected transitory ischaemic attack (TIA) or ischaemic stroke. METHODS: Cardiologists, experienced in carotid ultrasound, examined patients admitted to a community hospital with suspected stroke or TIA. Patients were first examined by an HUD and second by HIGH as per usual care. Different operators performed HUD and HIGH blinded to each other. On clinical discretion, CT angiography (CTA) was performed, and analysed by a radiologist blinded to the results from the ultrasound. RESULTS: Of 80 patients included, 9 (11%) were found to have >50% internal carotid artery (ICA) stenosis on reference examination. Agreement for classification of the degree of ICA stenosis was good for HUD versus HIGH (weighted Kappa 0.76) and HUD versus CTA (weighted Kappa 0.66). Agreement between HUD and HIGH examinations was excellent when ICA was classified as <50% diameter stenosis by HUD (99% agreement), but significantly lower when ICA diameter stenosis was classified as >50% by HUD (OR 0.15, 95% CI 0.06 to 0.42). Overall, HUD tended to overestimate the degree of carotid stenoses rather than underestimate (p=0.048). CONCLUSION: Hand-held carotid ultrasound performed by experts demonstrated good agreement with conventional duplex ultrasound. The use of HUDs was reliable for ruling out significant carotid artery disease, but less reliable for ruling in significant disease.

Feasibility and Clinical Impact of Point-of-Care Carotid Artery Examinations by Experts using Hand-Held Ultrasound Devices in Patients with Ischemic Stroke or Transitory Ischemic Attack.

BACKGROUND AND PURPOSE: To evaluate the feasibility and clinical influence of carotid artery examinations in patients admitted with stroke or TIA with hand-held ultrasound by experts, to identify individuals not in need of further carotid artery diagnostics. MATERIALS AND METHODS: Cardiologists experienced in carotid ultrasound examined 80 patients admitted to a stroke unit with suspected stroke or TIA with hand-held ultrasound devices (HUD). Grey scale and color Doppler images were stored using a GE Vscan with dual probe (phased array and linear transducer). High-end triplex ultrasound performed by a cardiologist, blinded to the details of the HUD study, was performed in all patients and used as reference. Computer tomography angiography was performed when clinically indicated. RESULTS: Stroke or TIA was diagnosed in 62 (78%) patients. Age was median (range) 72 (23-93) years. A significant stenosis (> 50% diameter reduction) was ruled out in 61 (76%) of patients by the HUD examinations. Sensitivity and specificity for diagnosing a significant stenosis was 92% and 93%, respectively. One of 12 significant stenoses was missed by HUD. All four patients in need of surgery were identified by the HUD examination. Sensitivity and specificity to identify a significant stenosis by HUD was 87% and 83%, respectively, compared to CT angiography. CONCLUSION: HUD examinations of the carotid arteries by experts, using hand-held ultrasound devices, were feasible and may reduce the need for high-end diagnostic imaging of the carotid vessels in patients with stroke and TIA. Thus, HUD may improve diagnostic workflow in stroke units in the future.

Handheld ultrasound in training - The future is getting smaller!

Traditional ultrasound teaching is normally delivered using large, costly and often quite advanced cart-based systems. These carts are often large systems on wheels, usually limited to the departments that own them i.e. clinics, wards or radiology. Portability has been further improved by the development of laptop style systems, which are easier to wheel in-between patients/departments. In our experience and anecdotally, many of these systems can be intimidating to the novice and can lead to early attrition or poor uptake of ultrasound into clinical practice. Carts can also restrict the amount of training deliverable to practitioners, as they are limited in number due to cost and can take quite some time to boot up, reducing convenience. This dogma is being progressively changed with the advent of smaller handheld devices, some clearly within the financial grasps of most practitioners, and even to the point of medical schools offering students their own personal device.1,2 This relative inexpensiveness can lead to the purchase of these devices for novelty and convenience, over need. Obvious caution is needed in these circumstances, but with increased ease of purchase, better availability and inbuilt simplicity, ultrasound learning can be seamlessly integrated into day-to-day practice. This review discusses how one of the most disruptive innovations in modern medicine is changing ultrasound from a classic imaging modality to become integrated as the fifth pillar of clinical examination, and how these new devices can serve as springboards to more advanced ultrasound training. In fact, within what has become a bigger area of clinical examination, things are getting smaller.

Translation of Simultaneous Vessel Wall Motion and Vectorial Blood Flow Imaging in Healthy and Diseased Carotids to the Clinic: A Pilot Study.

This study aims to investigate the clinical feasibility of simultaneous extraction of vessel wall motion and vectorial blood flow at high frame rates for both extraction of clinical markers and visual inspection. If available in the clinic, such a technique would allow a better estimation of plaque vulnerability and improved evaluation of the overall arterial health of patients. In this study, both healthy volunteers and patients were recruited and scanned using a planewave acquisition scheme that provided a data set of 43 carotid recordings in total. The vessel wall motion was extracted based on the complex autocorrelation of the signals received, while the vector flow was extracted using the transverse oscillation technique. Wall motion and vector flow were extracted at high frame rates, which allowed for a visual appreciation of tissue movement and blood flow simultaneously. Several clinical markers were extracted, and visual inspections of the wall motion and flow were conducted. From all the potential markers, young healthy volunteers had smaller artery diameter (7.72 mm) compared with diseased patients (9.56 mm) ( p -value ≤ 0.001), 66% of diseased patients had backflow compared with less than 10% for the other patients ( p -value ≤ 0.05), a carotid with a pulse wave velocity extracted from the wall velocity greater than 7 m/s was always a diseased vessel, and the peak wall shear rate decreased as the risk increases. Based on both the pathological markers and the visual inspection of tissue motion and vector flow, we conclude that the clinical feasibility of this approach is demonstrated. Larger and more disease-specific studies using such an approach will lead to better understanding and evaluation of vessels, which can translate to future use in the clinic.

Maximum Velocity Estimation in Coronary Arteries Using 3-D Tracking Doppler.

Several challenges currently prevent the use of Doppler echocardiography to assess blood flow in the coronary arteries. Due to the anatomy of the coronary tree, out-of-plane flow and high beam-to-flow angles easily occur. Transit-time broadening in regions with high velocities leads to overestimation of the maximum velocity envelope, which is a standard clinical parameter for flow quantification. In this paper, a commercial ultrasound system was locally modified to perform trans-thoracic, 3-D high frame-rate imaging of the coronary arteries. The imaging sequence was then combined with 3-D tracking Doppler for retrospective estimation of maximum velocities. Results from simulations showed that 3-D tracking Doppler delivers sonograms with better velocity resolution and spectral SNR compared to conventional pulsed wave (PW) Doppler. Results were confirmed using in vitro recordings. Further simulations based on realistic coronary flow data showed that 3-D tracking Doppler can provide improved performance compared to PW Doppler, suggesting a potential benefit to patients. In vivo feasibility of the method was also shown in a healthy volunteer.

Maximum velocity estimation in coronary arteries using 3D tracking Doppler.

Several challenges currently prevent the use of Doppler echocardiography to assess blood flow in the coronary arteries. Due to the anatomy of the coronary tree, out-of-plane flow and high beam-to-flow angles easily occur. Transit time broadening in regions with high velocities leads to overestimation of the maximum velocity envelope, which is a standard clinical parameter for flow quantification. In this work, a commercial ultrasound system was locally modified to perform trans-thoracic, 3D high frame-rate imaging of the coronary arteries. The imaging sequence was then combined with 3D tracking Doppler for retrospective estimation of maximum velocities. Results from simulations showed that 3D tracking Doppler delivers sonograms with better velocity resolution and spectral SNR compared to conventional PW Doppler. Results were confirmed using in vitro recordings. Further simulations based on realistic coronary flow data showed that 3D tracking Doppler can provide improved performance compared to PW Doppler, suggesting a potential benefit on patients. In vivo feasibility of the method was also shown in a healthy volunteer.