The role of two-dimensional echocardiology in the diagnosis of infective endocarditis [corrected]

2020 ACC/AHA Guideline for the Management of Patients With Valvular Heart Disease: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This executive summary of the valvular heart disease guideline provides recommendations for clinicians to diagnose and manage valvular heart disease as well as supporting documentation to encourage their use.

METHODS

A comprehensive literature search was conducted from January 1, 2010, to March 1, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, Cochrane, Agency for Healthcare Research and Quality Reports, and other selected database relevant to this guideline. Structure: Many recommendations from the earlier valvular heart disease guidelines have been updated with new evidence and provides newer options for diagnosis and treatment of valvular heart disease. This summary includes only the recommendations from the full guideline which focus on diagnostic work-up, the timing and choice of surgical and catheter interventions, and recommendations for medical therapy. The reader is referred to the full guideline for graphical flow charts, text, and tables with additional details about the rationale for and implementation of each recommendation, and the evidence tables detailing the data considered in developing these guidelines.

Infective endocarditis in infants and children

Due to changing characteristics of infective endocarditis in the past two decades, we, retrospectively analysed 28 cases of infective endocarditis in children of age less than 15 years at Sher-i-Kashmir Institute of Medical Sciences, Soura, Srinagar from December, 1983 to November, 1993. The incidence of disease was observed as 1.5 cases/1000 children admitted with a M:F ratio of 2:1. Three patients were of age less than 2 years (group I) as 25 were above 2 years of age (group II). The two groups had significant difference in portal of entry of infection, infective microorganisms, echocardiography and prognosis. Congenital heart disease was the commonest underlying cardiac lesion in 24 (85.71%) patients. Portal of entry of infection was apparent in 35.71% only; dental route being more frequent in group II. Streptococcus viridans (in 9 cases) followed by staphylococcus aureus (in 4 cases) were the two common organisms isolated. Patients were treated, for a period of 4-6 weeks with a over all mortality rate of 25%. Factors associated with poor prognosis were age < 2 years, staphylococcal infection ad negative blood cultures. Heart failure resistant to medical therapy was a leading cause of death.

Effect of electrical stimulus parameters on the development and propagation of action potentials in short excitable fibres

Intracellular action potentials (IAPs) produced by short fibres in response to their electrical stimulation were analysed. IAPs were calculated on the basis of the Hodgkin-Huxley (1952) model by the method described by Joyner et al. (1978). Principal differences were found in processes of activation of short (semilength L less than 5 lambda) and long fibres under near-threshold stimulation. The shorter the fibre, the lower was the threshold value (Ithr). Dependence of the latency on the stimulus strength (Ist) was substantially non-linear and was affected by the fibre length. Both fibre length and stimulus strength influenced the IAP amplitude, the instantaneous propagation velocity (IPV) and the site of the first origin of the IAP (and, consequently, excitability of the short fibre membrane). With L less than or equal to 2 lambda and Ithr less than or equal to Ist less than or equal to 1.1Ithr, IPV could reach either very high values (so that all the fibre membrane fired practically simultaneously) or even negative values. The latter corresponded to the first origin of the propagated IAP, not at the site of stimulation but at the fibre termination or at a midpoint. The characters of all the above dependencies were unchanged irrespective of the manner of approaching threshold (variation of stimulus duration or its strength). Reasons for differences in processes of activation of short and long fibres are discussed in terms of electrical load and latency. Applications of the results to explain an increased jitter, velocity recovery function and velocity-diameter relationship are also discussed.