Aortic regurgitation management: a systematic review of clinical practice guidelines and recommendations

Guidelines for the diagnosis and management of aortic regurgitation (AR) contain recommendations that do not always match. We systematically reviewed clinical practice guidelines and summarized similarities and differences in the recommendations as well as gaps in evidence on the management of AR. We searched MEDLINE and Embase (1 January 2011 to 1 September 2021), Google Scholar, and websites of relevant organizations for contemporary guidelines that were rigorously developed as assessed by the Appraisal of Guidelines for Research and Evaluation II tool. Three guidelines met our inclusion criteria. There was consensus on the definition of severe AR and use of echocardiography and of multimodality imaging for diagnosis, with emphasis on comprehensive assessment by the heart valve team to assess suitability and choice of intervention. Surgery is indicated in all symptomatic patients and aortic valve replacement is the cornerstone of treatment. There is consistency in the frequency of follow-up of patients, and safety of non-cardiac surgery in patients without indications for surgery. Discrepancies exist in recommendations for 3D imaging and the use of global longitudinal strain and biomarkers. Cut-offs for left ventricular ejection fraction and size for recommending surgery in severe asymptomatic AR also vary. There are no specific AR cut-offs for high-risk surgery and the role of percutaneous intervention is yet undefined. Recommendations on the treatment of mixed valvular disease are sparse and lack robust prospective data.

Feasibility and reproducibility of right ventricle stress echocardiography and its capability to assess the right ventricle contractile reserve of patient with at least trivial tricuspid regurgitation

Funding Acknowledgements

Type of funding sources: None.

BACKGROUND. Stress echocardiography (SE) is widely used for the assessment of left ventricular (LV) function, diagnostic and prognostic stratification of patients with coronary artery disease and for assessment of mitral and aortic valve disease. However, the assessment of the right ventricle (RV) in general, and in particular in regard to the contractile reserve of the RV in patients with tricuspid valve (TV) disease is an area that has not been previously explored in adult patients. The physiology and function of the RV is different than that of the LV and the use of SE provides the possibility to test both systolic and diastolic function of the RV in response to increased loading conditions. This can potentially be used to assess the RV function prior to surgery  and to predict which subset of patients may benefit from intervention on the TV before the RV displays signs of failure

PURPOSE. We therefore propose a study to investigate the potential use of SE for the assessment of RV function in adult patients. The aim is to evaluate the feasibility of RV SE in any patients with more than trivial tricuspid regurgitation (TR) and to assess the presence and degree of RV contractile reserve.

METHODS. We enrolled 81 patients undergoing a phisical or dobutamine SE for CV risk stratification or chest pain. Inclusion criteria were age≥ 18 years, normal baseline RV function (FAC> 35%, TAPSE> 16 mm). Exclusion criteria were presence of RV dysfunction, pulmonary stress hypertension, positive stress test for left myocardial ischemia, presence of moderate or severe valvular disease, grade III or higher diastolic dysfunction at baseline, severe respiratory, renal or hepatic dysfunction. We evaluated the average values of TAPSE, fractional area change (FAC), S wave, sPAP (pulmonary systolic blood pressure), RV strain during baseline and at the peak of the effort. We also assessed the reproducibility of these measurement between two different expert operators (blind analysis).

RESULTS. We were able to measure the RV parameters both during baseline and at the peak of the effort in all patients, demonstrating an excellent feasibility. Differences in parameters collected at baseline and at peak were assessed using paired Wilcoxon signed rank test. All variables showed a statistical significant increase (p < 0.001) at peak compared to the baseline. Average percentage increases at peak were 31.1% for TAPSE, 24,8% for FAC, 50,6% for S wave, 55,2% for PAPS and 39.8 % for RV strain. Bland-Altman method was used to evaluate the agreement between measurements collected by two separate operators and it showed  good Intraclass Correlation Coefficients  (Figure).

CONCLUSIONS. RV SE proved to be feasible and showed little inter-operator variability  in patients with at least trivial TR. It provided valuable informations about RV contractile  reserve that may help stratifying the risk of RV failure in patients undergoing TV surgery.

Abstract Figure

Anisotropic spin relaxation in graphene

Spin relaxation in graphene is investigated in electrical graphene spin valve devices in the nonlocal geometry. Ferromagnetic electrodes with in-plane magnetizations inject spins parallel to the graphene layer. They are subject to Hanle spin precession under a magnetic field B applied perpendicular to the graphene layer. Fields above 1.5 T force the magnetization direction of the ferromagnetic contacts to align to the field, allowing injection of spins perpendicular to the graphene plane. A comparison of the spin signals at B=0 and B=2 T shows a 20% decrease in spin relaxation time for spins perpendicular to the graphene layer compared to spins parallel to the layer. We analyze the results in terms of the different strengths of the spin-orbit effective fields in the in-plane and out-of-plane directions and discuss the role of the Elliott-Yafet and Dyakonov-Perel mechanisms for spin relaxation.

All-optical probe of coherent spin waves

A novel, all-optical method to excite and detect spin waves in magnetic materials is presented. By exploiting the temperature dependence of the magnetic anisotropy, an ultrashort laser pulse is efficiently converted in a picosecond "anisotropy field" pulse that triggers a coherent precession of the magnetization. Recording the temporal evolution of the precessing spins by a time-delayed probe-pulse provides a quantitative method to study locally the magnetic anisotropy, as well as switching and damping phenomena in micromagnetic structures. Applications to nickel and permalloy ( Ni80Fe20) films are discussed, particularly showing the possibility to explore standing spin waves in thin films.