Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
➤ Gửi thông báo lỗi ⚠️ Báo cáo tài liệu vi phạmNội dung chi tiết: Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
Area and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. Abba Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2as8AbstractWhile the clinical severity of aortic stenosis (AS) is based largely on symptoms. indications for surgical aortic valve replacement (SAVR) and/or transcutaneous (TAVR > rely upon calculated estimates of the hemodynamic significance and degree of valvular stenosis. Severe AS is defined as Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2an aortic valve area (AVA) < 1.0 cm* or indexed AVA <0.6 cnr/nr, mean trans-valvular pressure gradient (AP) >40 mmHg, and/or peak trans-aortic velocitEbook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
y >4 m/s by Doppler echocardiography. Whether the above conditions must be met individually or collectively remains unclear. As noted, "area/ gradientArea and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. Abba Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2n and regardless of the presence or absence of low flow (defined as a stroke volume index on echocardiography <35 liil/ni2). However, the AVA may be in the severe range, while the gradient may be in the non-severe range. This has been referred to as area/gradient mismatch and will be discussed furth Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2er in this chapter.KeywordsAortic stenosis severity ♦ Surgical aortic valve replacement (SAVR) • Transcutaneous aortic valve replacement (TAVR) • AreaEbook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
/gradient match • Low flow area-gradient mismatchL.M. Franey, MD (S) • F.o. Wood, MD A.E. Abbas. MD. FACC. FSCAI. FSVM. FASE. RPVI (K)Department of CaArea and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. Abba Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2bbas (a beaumonl.eduSJ. Lester. MDDepartment of Medicine. Mayo Clinic.Scottsdale. AZ. USAo Springer-Verlag London 2015A.E. Abbas (ed.). Aortic Stenosis: Case-Based Diagnosis and Therapy.DOI 10.1007/978-1 -4471-5242-2-8117118L.M. Franey et al.IntroductionWhile the clinical severity of aortic stenosis Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2 (AS) is based largely on symptoms, indications for surgical aortic valve replacement (SAVR) and/or transcutaneous (TAVR) rely upon calculated estimatEbook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
es of the hemodynamic significance and degree of valvular stenosis. Severe AS is defined as an aortic valve area (AVA) <1.0 cm2 or indexed AVA <0.6 cmArea and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. Abba Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2ove conditions must be met individually or collectively remains unclear |3). As noted, "area/gradient match" occurs when both the AVA and AP fall within the severe range. This may occur regardless of the presence of normal or abnormal ejection fraction and regardless of the presence or absence of lo Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2w flow (defined as a stroke volume index on echocardiography <35 ml/nr) |4J.In the presence of measurement or assumption errors, discordance of area aEbook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
nd gradient measures of AS severity may occur. Additionally, this discordance may occur with a decrease in transvalvu-lar flow that causes a decline iArea and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. Abba Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2 such, in the presence of low flow states, clinical scenarios may arise where the AVA suggests severe AS while the AP falls within the non-severe range. We previously proposed the term "area-gradient mismatch" to describe such a clinical entity of discordant area and gradient measures of AS severity Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2 [7|. This chapter will summarize common etiologies and examples of area-gradient mismatch including errors of measurement and/or assumption, and lowEbook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
flow states with and w ithout preserved left ventricular ejection fraction (LVEF). The clinical approach to patients presenting with area-gradient misArea and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. Abba Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2alve area by Doppler echocardiography [8]. The continuity equation assumes the LVOT is circular with area equal to n r. As such, any error in measurement of the LV0T diameter is magnified exponentially |7|. Even with accurate measurement of the LVOT diameter with echocardiography, studies have show Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2n that 2D echo-derived LVOT area underestimates the true LVOT area, as assessed by CTA or 3D echocardiography by about 17 %± 16 %.Moreover, velocitiesEbook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
obtained by Doppler must have parallel intercept angles with the direction of trans-valvular flow, limiting underestimation of amplitude parameters aArea and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. Abba Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2ce of measurement error and is resolved by averaging several beats [9).With catheter-based techniques, measurement errors in cardiac output and AP may lead to errors in AVA calculations by the Gorlin formula. AP is obtained via a double lumen single catheter, dual catheters, or pull back of a single Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2 catheter across the AV. Poor balancing, air bubbles in transducers, or the positioning of the transducer either loo high or too low in relation to thEbook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
e patient may account for errors. Moreover, utilizing the pressure difference between the left ventricular catheter and the femoral line rather than tArea and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. Abba Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2s in estimating the cardiac output may also account for errors of area measurement as may occur with utilizing an erroneous constant, utilizing estimated rather than measured Oj consumption with Fick method, or using the thermodilution method with severe tricuspid regurgitation, atrial fibrillation, Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2 or low' cardiac output. Finally, reports of the flow dependency of the constant in the Gorlin equation may also explain potential measurement errorsEbook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
with flow variations.Errors of MeasurementErrors of AssumptionThe continuity equation, based on the principle conservation of mass (that flow across tArea and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. Abba Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2 measured of AVA <1.0 cm2 will still have8 Area and Gradient Mismatch: The Discordance of a Small Valve Area and Low Gradients119APmcM <40 mmHg by Doppler echocardiography I3Ị. Current clinical guidelines do not stale whether an AVA <1.0 cm2 is sufficient to determine severe stenosis, or whether a A Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2Pmc„ >40 mmHg is also required. Moreover, there is no differentiation between invasive and nonin-vasive measurements |7|. After excluding erroneous ecEbook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
hocardiographic data and low flow conditions, one catheterization study of AS patients confirmed the above scenario to be present in 48 % of area-gradArea and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. Abba Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2s 110]. By example, according to the Gorlin formula, an AVA of <0.81 cm2 results in an expected APmcjn of 40 mmHg, however with an AVA of I cm2, the expected APmean is only 28 mmHg [2, 3]. Thus, despite a calculated AVA <1 cm2 under normal flow conditions, the APmc>o may remain lower than the assume Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2d 40 mmHg (normal flow/low-gradient or NF/LG AS). Normal flow/low gradient AS is considered an early form of the disease with the best clinical prognoEbook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2
sis and a 3-year cardiac event-free survival of 66 % |4]. Nevertheless, in clinical practice APmc.jn >40 mmHg are often generated in patients with an Area and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. Abba Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2 to clinical cases of area-gradient mismatch. Such scenarios may occur with either a depressed or preserved LVEF and render lower than expected pressure gradients in the setting of an AVA <1 cm2 [3]. Ebook Aortic stenosis - Case-Based diagnosis and therapy (1st edition): Part 2Area and Gradient Mismatch: The Discordance of a Small Valve Area and Low GradientsLaura M. Franey, Steven J. Lester, Frances o. Wood, and Amr E. AbbaGọi ngay
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