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Low flow low gradient aortic stenosis

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LFLG AS

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Low flow low gradient aortic stenosis

  1. 1. LOW FLOW LOW GRADIENT AORTIC STENOSIS 25-2-2016
  2. 2. OUTLINE  Introduction  Low flow Low gradient AS with Low EF  Low flow Low gradient AS with Normal EF  Normal-Flow, Low-Gradient AS.  Treatment  Conclusions LOW FLOW LOW GRADIENT AS
  3. 3. Introduction Aortic stenosis is one of the common valve disorders encountered in clinical practice and one of the most frequent indications for valve surgery. Prevalence is 2-7% over the age of 65 years Evaluation of AS is challenging of all VHD LOW FLOW LOW GRADIENT AS
  4. 4.  Long asymptomatic phase: risk of sudden death low  Mortality ↑: exertional chest pain, syncope, breathlessness  Mortality up to 12% soon after onset of symptoms  Significant AS and LV dysfunction: poor prognoses  Importantly as many as 30% of patients who have a calculated AVA in the severe range have other parameters suggesting mild or moderate disease (ie, mean gradient <30 mm Hg) LOW FLOW LOW GRADIENT AS
  5. 5. Valvular AS has three principal causes: a congenital BAV with superimposed calcification, calcification of a normal trileaflet valve, and Rheumatic disease LOW FLOW LOW GRADIENT AS
  6. 6. Major types of aortic valve stenosis. A, Normal aortic valve. B, Congenital bicuspid AS. A false raphe is present at 6 o’clock. C, Rheumatic AS. The commissures are fused with a fixed central orifice. D, Calcific degenerative AS. LOW FLOW LOW GRADIENT AS
  7. 7. STAGES OF VALVULAR AS LOW FLOW LOW GRADIENT AS
  8. 8. Nishimura RA, Otto CM, Bonow RO, et al: 2014 AHA/ACCF guideline for the management of patients with valvular heart disease: A report of the American College ofCardiology Foundation/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 63:e57, 2014. LOW FLOW LOW GRADIENT AS
  9. 9.  As the severity of AS increses there will be corresponding increase in the TVPG (ΔP) and myocardial pressure overload Though the preload reserve, the LV compensates for the increased workload until the sarcomeres stretch to their maximum diastolic length. Once the preload reserve is exhausted, increases in afterload are accompanied by a reduction in stroke volume (SV), resulting in afterload mismatch LOW FLOW LOW GRADIENT AS
  10. 10. Various Hemodynamic Metrics Used for Assessment of AS and Their Cutoff Values for Severe AS LOW FLOW LOW GRADIENT AS
  11. 11. Percentage of patients diagnosed with severe AS based on various echocardiographic criteria Minners et al Eur.HEART .journal 2008:29;1043-8 Inconsistencies of echocardiographic criteria for grading of AS LOW FLOW LOW GRADIENT AS
  12. 12. Moderate stenosis for a normal ventricle may correspond to a severe stenosis for a diseased ventricle in terms of hemodynamic load LOW FLOW LOW GRADIENT AS
  13. 13. Effect of concurrent conditions …… Left ventricular systolic dysfunction Left ventricular hypertrophy Small ventricular cavity & small LV ejects a small SV so that, even in severe AS the AS velocity and mean gradient may be lower than expected.  Continuity-equation valve area is accurate in this situation LOW FLOW LOW GRADIENT AS
  14. 14. Hypertension 35–45% of patients primarily affect flow and gradients but less AVA measurements Control of blood pressure is recommended The echocardiographic report should always include a blood pressure measurement Effect of concurrent conditions contd… LOW FLOW LOW GRADIENT AS
  15. 15. Aortic regurgitation  About 80% of adults with AS also have aortic regurgitation High transaortic volume flow rate, maximum velocity, and mean gradient will be higher than expected for a given valve area Effect of concurrent conditions contd… LOW FLOW LOW GRADIENT AS
  16. 16. High cardiac output Relatively high gradients in the presence of mild or moderate AS The shape of the CWD spectrum with a very early peak may help to quantify the severity correctly Ascending aorta Aortic root dilation Coarctation of aorta LOW FLOW LOW GRADIENT AS
  17. 17. The transaortic gradient depends upon the severity of the stenosis and upon flow rate, which is determined by the stroke volume and systolic ejection period GRADIENT = Flow Dependent Variable Gradient calculation- Small reduction in flow can cause great reductions in gradient LOW FLOW LOW GRADIENT AS
  18. 18. AVA calculation is a standard and must be incorporated into a comprehensive evaluation of AS severity AVA= Flow independent variable LOW FLOW LOW GRADIENT AS
  19. 19.  The gradients across a stenosd valve are a squared function of flow, even a modest decrease in flow may lead to an important reduction in gradient, even if the stenosis is very severe. Symptomatic patients with severe AS generally have a substantial improvement in symptoms and increased survival after AVR.  Precise assessment of both the severity of valve stenosis and the degree of myocardial impairment is thus crucial for good therapeutic management. LOW FLOW LOW GRADIENT AS
  20. 20. LOW FLOW LOW GRADIENT AS
  21. 21. Prevalence of low flow state Low EF 5- 10 % of all patients of AVA < 1.0 Preserved EF 10-25 % of all patients of AVA < 1.0 Pibarot P, Dumesnil J. Low-Flow, Low-Gradient Aortic Stenosis With Normal and Depressed Left Ventricular Ejection Fraction. J Am Coll Cardiol 2012;60:1845–53 LOW FLOW LOW GRADIENT AS
  22. 22. Till 2007 low flow due to Low EF Now Low flow can also be with Preserved EF “new entity” Paradoxical Low flow AS Hachicha Z, Dumesnil JG, Bogaty P, Pibarot P. Paradoxical low flow, low gradient severe aortic stenosis despite preserved ejection fraction is associated with higher afterload and reduced survival. Circulation 2007;115:2856–64 Pibarot P, Dumesnil J. Low-Flow, Low-Gradient Aortic Stenosis With Normal and Depressed Left Ventricular Ejection Fraction. J Am Coll Cardiol 2012;60:1845–53 LOW FLOW LOW GRADIENT AS
  23. 23. TYPES OF LOW FLOW AS LOW FLOW LOW GRADIENT AS
  24. 24. Classical Low Flow Low Gradient AS with Low EF LOW FLOW LOW GRADIENT AS
  25. 25. Prevalence of LF –LG –AS with Low EF  A LF-LG severe AS with Low LVEF may be observed in approximately 5% to 10% of patients with severe AS.  Such patients are classically characterized by a dilated LV with markedly decreased LV systolic function, most often due to IHD and/or to after load mismatch  Prognosis is usually poor (survival rates 50% at 3-year follow-up) if treated medically, but operative risk is high (6% to 33%) if treated surgically LOW FLOW LOW GRADIENT AS
  26. 26. LF LG AS with Low EF Low LVEF, LF-LG severe AS is generally characterized by the combination of an EOA≤1.0 cm2 or ≤0.6 cm2/m2 when indexed for BSA, a low mean transvalvular gradient (i.e.,<40 mm Hg) and a low LVEF (≤40%), causing an LF state. LOW FLOW LOW GRADIENT AS
  27. 27. Several criteria have been proposed in the literature to define the LF state in AS, including a cardiac index <3.0 l/min/m2 and a stroke volume index < 35 ml/m2 Given that the gradient essentially depends on the flow per beat (i.e., the stroke volume) rather than on the flow per minute (i.e., the cardiac output), the former is the most frequently used parameter in this context LOW FLOW LOW GRADIENT AS
  28. 28. Patients with critical AS, severe LV dysfunction, and low cardiac output (low TVG) often create diagnostic dilemmas for the clinician because their clinical presentation and hemodynamic data may be indistinguishable from those of patients with a DCMP and a calcified valve that is not severely stenotic. LOW FLOW LOW GRADIENT AS
  29. 29. The main diagnostic challenge in LF-LG AS with low LVEF is to distinguish true severe from Pseudo severe AS.  In the former, the primary culprit is deemed to be the valve disease, and the LV dysfunction is a secondary or concomitant phenomenon. LOW FLOW LOW GRADIENT AS
  30. 30. The predominant factor in pseudosevere AS is deemed to be myocardial disease, and AS severity is overestimated due to incomplete opening of the valve in relation to the LF state. Distinction between these two entities is essential because patients with true severe AS generally benefit from AVR, whereas those with pseudo severe AS may not benefit. LOW FLOW LOW GRADIENT AS
  31. 31. PATHOPHYSIOLOGY  Low Flow secondary to Low EF  Low EF is due to myocardial dysfunction “whether this myocardial dysfunction is -secondary to AS -secondary to other causes, or -primary myocardial disease, needs to be evaluated” LV dysfunction in patients with AS is referred to as primary if decreased function is caused primarily by factors other than a stenotic aortic valve.  secondary if decreased function results directly from the valvular lesion. LOW FLOW LOW GRADIENT AS
  32. 32. -DCMP(1O Myocardial Dysfunction) -Ischemic Heart Disease -HTN Heart Disease (After load mismatch) In these patients, AVA was misjudged as <1.0 due to incomplete opening of AV due to low EF and  labelled as “PSEUDO SEVERE AS” LOW FLOW LOW GRADIENT AS
  33. 33. “ True severe AS” Removal of the only afterload-AS can lead to dramatic improvements in patients’ symtoms/survival compared to medical therapy alone LOW FLOW LOW GRADIENT AS
  34. 34. DIAGNOSIS First suspicion Gradient-AVA Mismatch during routine echo Gradient < 40 mmhg, AVA <1.0, EF <40 % • Dobutamine stress echo LOW FLOW LOW GRADIENT AS
  35. 35. LOW FLOW LOW GRADIENT AS
  36. 36.  The term “flow reserve” is utilized rather than “contractile reserve” because several mechanisms not necessarily related to intrinsic contractility may contribute to the lack of stroke volume increase during DSE. 1) afterload mismatch due to an imbalance between the severity of the stenosis and myocardial reserve 2) inadequate increase of myocardial blood flow due to associated CAD; and/or 3) irreversible myocardial damage due to previous myocardial infarction or extensive myocardial fibrosis. LOW FLOW LOW GRADIENT AS
  37. 37. DSE  De Filippi et al. were the first to demonstrate that low-dose (up to 20 µg/kg/min) DSE) may be used in these patients to assess the presence of LV flow reserve and to distinguish true versus pseudo severe stenosis.  The use of DSE for this purpose has received a Class IIa (Level of Evidence: B) recommendation in the (ACC/AHA-ESC/EACTS) guidelines DeFilippi CR, Willett DL, Brickner E, et al. Usefulness of dobutamine echocardiography in distinguishing severe from nonsevere valvular aortic stenosis in patients with depressed left ventricular function and low transvalvular gradients. Am J Cardiol 1995;75:191–4. LOW FLOW LOW GRADIENT AS
  38. 38. Provides information on the changes in aortic velocity, mean gradient, and valve area as flow rate increases. Measure of the contractile response to dobutamine Helpful to differentiate two clinical situations Severe AS with LV systolic dysfunction Moderate AS with another cause of LV dysfunction LOW FLOW LOW GRADIENT AS
  39. 39. Low dose protocol up to 20 µg/kg/mt We look for three things: -Flow reserve -Change in EOA -Change in Gradient and velocity LOW FLOW LOW GRADIENT AS
  40. 40.  The Dobutamine infusion protocol consisted of 8-min increments of 2.5 to 5 µg/kg/min, starting at 2.5 µg/kg/min up to a maximum dosage of 20 µg/kg/min.  At high doses there is likelihood of dobutamine- induced LVOT obstruction and drop in BP and arrhythmias during the test.  The infusion should be stopped as soon as Positive result is obtained Heart rate begins to rise more than 10–20 bpm over baseline or exceeds 100bpm LOW FLOW LOW GRADIENT AS
  41. 41. Monin JL, Monchi M, Gest V, Duval-Moulin AM Dubois-Rande JL, Gueret P. Aortic stenosis with severe left ventricular dysfunction and low transvalvular pressure gradients: risk stratification by low-dose dobutamine echocardiography. J Am Coll Cardiol. 2001;37:2101–2107LOW FLOW LOW GRADIENT AS
  42. 42. Role in decision-making in adults with AS is controversial and the findings recommend as reliable are Stress findings of true severe stenosis AVA<1cm² Jet velocity>4m/s Mean gradient>40mm of Hg Nishimura RA et al. Circulation 2002;106:809-13. Lack of contractile reserve- Failure of LVEF to ↑ by 20% is a poor prognostic sign Monin JL et al. Circulation 2003;108:319-24.. LOW FLOW LOW GRADIENT AS
  43. 43.  Several parameters and criteria have been proposed in the literature to identify patients with pseudosevere AS during DSE, • Including a peak stress mean gradient ≤30 or ≤40 mm Hg depending on studies, a peak stress EOA >1.0 or 1.2 cm2, and/or an absolute increase in EOA >0.3 cm2 thus, the optimal cutoff values remain to be determined. • The prevalence of pseudosevere AS is reported to be between 20% and 30% LOW FLOW LOW GRADIENT AS
  44. 44.  In patients with fixed AS, dobutamine induced an increase in peak velocity, mean TVPG, and valve resistance and no change in valve area.  Therefore, DSE clearly can help to differentiate patients with fixed LG AS (who will benefit from AVR) from those with pseudo-AS (in whom AVR is not indicated). Monin J, Quéré J, NMonchi M, et al. Low-gradient aortic stenosis operative risk stratification and predictors for long-term outcome: a multicenter study using dobutamine stress hemodynamics. Circulation. 2003;108:319– 324. LOW FLOW LOW GRADIENT AS
  45. 45. Subjects with LG AS who manifest an increase in peak velocity (>0.6 m/s), SV (>20%), or mean TVPG (>10 mm Hg) with DSE have LV flow reserve and would benefit from AVR. In contrast, the absence of these changes with DSE identifies patients without LV flow reserve whose operative risk might be high. LOW FLOW LOW GRADIENT AS
  46. 46. Patients with no LV flow reserve are defined by a percent increase in SV <20% during DSE or catheterization , and have higher operative mortality (22% to 33%) than those with flow reserve (5% to 8%).  They have a higher prevalence of multivessel CAD The absence of LV contractile reserve should not preclude consideration of AVR surgery in symptomatic subjects with severe AS and a TVPG.  Even for these individuals, valve replacement surgery is the treatment of choice. LOW FLOW LOW GRADIENT AS
  47. 47. Some patients shows an ambiguous response to DSE (e.g., a peak gradient of 29 mm Hg and an EOA of 0.8 cm2) due to variable increases in flow , and interpreting the changes in EOA and gradients without considering the relative changes in flow may often be problematic. LOW FLOW LOW GRADIENT AS
  48. 48. The differentiation between true and pseudo- AS may be improved by using other noninvasive parameters, such as the projected valve area at a normal flow rate An echo method that attempts to control for the variable augmentation of transaortic flow induced by dobutamine. LOW FLOW LOW GRADIENT AS
  49. 49. Projected EOA  The investigators of the TOPAS(Truly or Pseudo-Severe AS) study proposed new parameter that is the Projected EOA that would have occurred at a standardized flow rate of 250 ml/s (EOA proj).  This new parameter has been shown to be more closely related to actual AS severity, impairment of myocardial blood flow, LV flow reserve, and survival than the traditional DSE parameters.  The full potential of the EOAProj remains to be determined by future studies LOW FLOW LOW GRADIENT AS
  50. 50. Patients with no increase in SV may nonetheless have an increase in mean flow rate sufficient to allow a reliable measurement of EOA Proj; this is due to shortening of LV ejection time in relation to an increase in heart rate  However, there are 10% to 20% of patients in whom the increase in flow rate is insufficient to allow calculation of EOA Proj LOW FLOW LOW GRADIENT AS
  51. 51. Projected EOA TOPAS (True or Pseudo Severe AS) STUDY LOW FLOW LOW GRADIENT AS
  52. 52. CT AV Calcium Scoring Cueff et al. suggested that a score >1,650 Agatston units provides good accuracy (93 % sensitive, 75 % specific) to distinguish true severe from pseudosevere AS LOW FLOW LOW GRADIENT AS
  53. 53. LOW FLOW LOW GRADIENT AS
  54. 54. Treatment Symptomatic status Valvular severity “Any symptomatic severe AS, Irrespective of EF and Flow reserve , has to be Intervened (class I)” WITHOUT AVR, 1 YR. MORTALITY IS 30-50% (Turina et al EhJ 1987)LOW FLOW LOW GRADIENT AS
  55. 55. Severe ‘Asymptomatic’ AS WITH LOW EF Recommendation: AVR for patients who have no symptoms and whose left ventricular EF is less than 50% (class I C) LOW FLOW LOW GRADIENT AS
  56. 56. The ACC/AHA guidelines (2014 )& ESC/ EACTS guidelines support the utilization of AVR (Class IIa; Level of Evidence: C) in the subset of patients with LV flow reserve LOW FLOW LOW GRADIENT AS
  57. 57. • In the ESC/EACTS guidelines AVR received a Class IIb (Level of Evidence: B) recommendation for patients with low LVEF, LF-LG AS, and no LV flow reserve. LOW FLOW LOW GRADIENT AS
  58. 58. • EURO SCORE, STS SCORE • PERIOP RISK- FLOW RESERVE (+)=5-8%,FLOW RESERVE (-)=30%*LOW FLOW LOW GRADIENT AS
  59. 59. Concerns after AVR Patient-Prosthesis Mismatch Low EF patients are known to be more vulnerable than patients with normal LVEF to the excess in LV load Can cause acute decompensation of LV or inadequate improvement of LV functions after AVR LOW FLOW LOW GRADIENT AS
  60. 60. Role of TAVI Operative risk for SAVR is generally very high in absence of flow reserve TAVI - valuable alternative in these patients Recent studies reported a greater and more rapid improvement of LVEF in patients treated by TAVR than those treated by surgical AVR * Rationale related to a lesser incidence of patient–prosthesis mismatch. LOW FLOW LOW GRADIENT AS
  61. 61. In contrast, TAVR associated with a higher incidence of paravalvular regurgitation, stroke, vascular complications which may eventually have a negative impact on outcomes *Clavel et al. Circulation 2010;122:1928 –36 Further randomized studies comparing surgery versus TAVR in LF-LG AS patients are warranted. LOW FLOW LOW GRADIENT AS
  62. 62. LOW FLOW LOW GRADIENT AS
  63. 63. • Normal flow reserve: Medical followup every 6 months vs AVR (ESC class IIa)–based on the clinician’s judgement • Low flow reserve: 1.IHD-OMT ± revascularisation 2.HTN- to be treated 3.Optimal heart failure management strategy 4.AVR (ESC class IIb) LOW FLOW LOW GRADIENT AS
  64. 64. Prognosis  Concomitant CAD  Low EF severe AS compared to Normal EF severe AS have higher peri op mortality rates (6-33%), depending on presence of myocardial contractile reserve (5-8%) or not (22- 33%)  But irrespective of degree of myocardial dysfunction or contractile reserve, the patients benefit more from AVR than medical treatment only “Severe LV dysfunction is not a CI for AVR, albeit the high risk of surgery in these patients” LOW FLOW LOW GRADIENT AS
  65. 65. Group I= Flow reserve + Group II= Flow reserve - LOW FLOW LOW GRADIENT AS
  66. 66. Prognstic factors  Reduced functional capacity as assessed by Duke Activity Score Index (<20) or by 6-MWT (<320 m),  Presence of CAD  More severe stenosis as assessed by EOA Proj< 1.2 cm2,  Reduced peak stress LVEF (<35%)  A high plasma BNP level (>550 pg/ml) would also appear to be a powerful predictor of mortality in patients with LF-LG AS regardless of treatment (medical vs. surgical) or the presence and/or absence of flow reserve LOW FLOW LOW GRADIENT AS
  67. 67. Predictors of late mortality Preop. Contractile reserve EuroSCORE, STS score, Atrial fibrillation, Multivessel CAD, Low pre-operative gradient, High plasma levels of BNP, and Patient–prosthesis mismatch Myocardial viabilty Myocardial fibrosis LOW FLOW LOW GRADIENT AS
  68. 68. Low-Flow, Low-Gradient AS With Normal LVEF LOW FLOW LOW GRADIENT AS
  69. 69. Low-Flow, Low-Gradient AS With Normal LVEF  Normally patients with severe AS and preserved LVEF should necessarily have a high transvalvular gradient.  However a substantial proportion of patients with severe AS on the basis of EOA ≤ 1.0 cm2 and/or indexed EOA ≤0.6 cm2/m2 might develop a restrictive physiology, resulting in low cardiac output (i.e., stroke volume index <35 ml/m2) and lower than expected TVG (i.e., <40 mm Hg) despite the presence of a preserved LVEF (i.e., >50%); this clinical entity was labeled “paradoxical” LF-LG AS Hachicha Z, Dumesnil JG, Bogaty P, Pibarot P. Paradoxical low flow, low gradient severe aortic stenosis despite preserved ejection fraction isassociated with higher afterload and reduced survival. Circulation 2007;115:2856–64 LOW FLOW LOW GRADIENT AS
  70. 70. First reported in 2007 by Hacicha et al. in 512 pts. (Circulation) Echo Parameters: -Mean gradient < 40 mmhg, -AVA < 1.0 cm2, -Flow <35 ml/mt2, -EF≥50 % LOW FLOW LOW GRADIENT AS
  71. 71. LOW FLOW LOW GRADIENT AS
  72. 72. MG is directly proportional to the square of transvalvular flow, even small reductions in SV can result in significant reductions in the pressure gradient. SV reductions can occur even in the presence of apparently normal LVEF LOW FLOW LOW GRADIENT AS
  73. 73. Pathophysiology of Paradoxical LF LG AS It shares many pathophysiological and clinical similarities with normal LVEF heart failure The prevalence of these entities increases with older age, female gender, and concomitant presence of systemic HTN. Both entities are also characterized by a restrictive physiology, whereby LV pump function and thus SV are markedly reduced despite a preserved LVEF. LOW FLOW LOW GRADIENT AS
  74. 74.  Reduced systemic arterial compliance (SAC) is a frequent occurrence in elderly patients with AS in which SAC independently contributes to increased after load and decreased LV function.  In particular, patients with a markedly increased afterload as a result of the combination of severe AS and reduced SAC were observed to have decreased CO, which resulted in lower TVG and pseudo normalization of peripheral BP. LOW FLOW LOW GRADIENT AS
  75. 75.  The distinctive features of this entity are: more pronounced LV concentric remodeling and myocardial fibrosis both contributing to reduce the size, compliance, and filling of the LV.  Marked reduction in intrinsic LV systolic function, not evidenced by the LVEF, but rather by other more sensitive parameters directly measuring LV mid-wall or longitudinal axis shortening.  Longitudinal shortening is reduced to a larger extent in these patients due to more advanced fibrosis in the subendocardial layers.  Reduced LV longitudinal shortening was measured using either systolic mitral ring displacement or tissue Doppler imaging LOW FLOW LOW GRADIENT AS
  76. 76. Several studies reported that these patients have a worse prognosis than those with moderate AS or normal flow severe AS Mode of presentation of this entity often complicates the assessment of AS severity and therapeutic decision making LOW FLOW LOW GRADIENT AS
  77. 77.  The decrease in SV is primarily due to deficient ventricular filling in relation with the smaller cavity size rather than deficient ventricular emptying.  A normal LVEF should not be construed as being equivalent to normal LV flow output. LOW FLOW LOW GRADIENT AS
  78. 78. “Normal LVEF Does Not Mean Normal Myocardial Function” LVEF is a late and insensitive marker for study of LV functions Not too far that LVEF will be replaced by other better markers of LV function LOW FLOW LOW GRADIENT AS
  79. 79. Myocardial fibrosis Restrictive physiology Small LV cavity Resembles heart failure with preserved EF Pseudo-normalization of blood pressure Impaired LV function yet normal EF (around 50-60%) LOW FLOW LOW GRADIENT AS
  80. 80.  Distinguishing features of PLF when compared with NF patients are: (i) a higher level of global LV haemodynamic load reflected by higher valvulo-arterial impedance (Zva) (ii) smaller and relatively thicker ventricles; (iii) lower values for LV mid-wall radius shortening consistent with more pronounced intrinsic myocardial dysfunction (iv) a tendency to have a lower LVEF although remaining within the normal range. LOW FLOW LOW GRADIENT AS
  81. 81. Overall, these findings are consistent with a greater and probably more long standing increase in LV haemo dynamic load resulting in more pronounced concentric LV remodeling. These patients also have a significantly poorer prognosis than patients with NF; as well, their prognosis is also much poorer if treated medically rather than surgically LOW FLOW LOW GRADIENT AS
  82. 82. Valvulo-Arterial impedance (Zva  The LV in degenerative AS is often facing a double load, i.e. valvular plus vascular.  Zva parameter represents the cost in mmHg for each ml of blood indexed for BSA pumped by the LV.  Z va can easily be estimated during Doppler echo by adding the mean aortic gradient to the pepipheral systolic pressure measured by sphygmomanometry and dividing the result by SVi and it has been shown to be superior to the standard indices of AS severity in predicting LV dysfunction and patient outcome LOW FLOW LOW GRADIENT AS
  83. 83. Global LV afterload As a measure of global LV afterload valvulo arterial impedence is measured by the formula Zva= SBP+MAVG SVI Zva represents the valvular and arterial factors that oppose the ventricular ejection. LOW FLOW LOW GRADIENT AS
  84. 84. The global hemodynamic load imposed on the LV results from the summation of the valvular load and the arterial load. This global load can be estimated by calculating the valvulo arterial impedance. In patients with medium or large size ascending aorta, the impedance can be calculated with the standard Doppler mean gradient in place of the net mean gradient. LOW FLOW LOW GRADIENT AS
  85. 85. A measurement of “afterload” Just quantifies the total load, that helps in prognostication Values > 3.5 Zva (mmHg·mL-1·m2) call for reduction in load- (both valvular and vascular) Does not differentiate between the type of load –valvular vs vascular Does not differentiate moderate vs severe AS LOW FLOW LOW GRADIENT AS
  86. 86. Several studies reported that the level of global LV hemodynamic load, (Zva), is consistently much higher than that observed in patients with normal flow severe AS LOW FLOW LOW GRADIENT AS
  87. 87. Paradoxical LF LG AS Over all survival is impaired compared to NF Hachicha et al. Circulation. 2007;115:2856 -64 LOW FLOW LOW GRADIENT AS
  88. 88.  Markedly lower survival if medically treated, as compared with those who underwent AVR Hachicha et al. Circulation. 2007;115:2856 -64 LOW FLOW LOW GRADIENT AS
  89. 89. J Am Coll Cardiol Img. 2013;6(2):175-183 LOW FLOW LOW GRADIENT AS
  90. 90. AVAproj = AVApeak – AVArest x (250 -Qrest )+ AVArest Qpeak – Qrest Q= mean transvalvular flow rate Q= stroke volume LV ejection time, LOW FLOW LOW GRADIENT AS
  91. 91. Diagnosis Paradoxical LFLG AS • Step 1 ----Is the patient symptomatic NO --- exercise test --conservative management YES  Step 2 is the patient HTN YES ---optimise Anti HTN Rx and reasses NO or controlled HTN  Step 3 Is stenosis severe or pseudo severe DSE MDCT AVC (>1200 AU Female >2000AU Male)AVR LOW FLOW LOW GRADIENT AS
  92. 92. Differential diagnosis Patients with paradoxical LF-LG AS should always be distinguished from patients with True severe AS based on EOA <1.0 cm2 and LG (i.e.<40 mm Hg) but normal flow (i.e., stroke volume index >35 ml/m2) The features of restrictive physiology or of a marked increase in Zva are conspicuously absent LOW FLOW LOW GRADIENT AS
  93. 93.  The discordance between EOA and gradient may be explained by one or more of the following. 1) measurement errors: that is, underestimation of stroke volume and AVA and/or underestimation of gradient 2) small body size: AS severity may be overestimated in a patient with a small body surface area if EOA is not indexed for body surface area 3) inherent inconsistencies in the guidelines criteria LOW FLOW LOW GRADIENT AS
  94. 94. Therapeutic management and outcome  A class IIa recommendation for AVR in the patients with paradoxical LF-LG and evidence of severe AS is however included in the recent ACC/AHA& ESC/EACTS guidelines.  Theoretically these patients were at higher operative risk given their myocardial impairment and their increased risk of having patient–prosthesis mismatch due to their small LV cavity. LOW FLOW LOW GRADIENT AS
  95. 95.  2014 ACCC guidelines class IIa C indication for AVR  “This subgroup of patients seems to be at a more advanced stage and has a poorer prognosis if treated medically rather than surgically”  It remains to be determined if TAVI could not be a better alternative in these patients Tarantini G, Covolo E, Razzolini R, et al. The Annals of Thoracic Surgery, Volume 91(6) LOW FLOW, NORMAL EF, SEVERE AS LOW FLOW LOW GRADIENT AS
  96. 96. The advantage of surgery is still present when other variables such as CAD are taken into account by performing propensity score– matched analysis.  It remains to be determined if TAVR could not be a better alternative in these patients. LOW FLOW LOW GRADIENT AS
  97. 97. Prognosis of paradoxical LF LG AS Worse than moderate AS (albeit contradictory reports) Worse than severe AS with high gradient group lower overall 3-year survival (76% versus 86%) (P<0.006 in 512 patients By Hacicha et al.) Two-fold increase in mortality and an almost 50% lower referral rate for AVR in the low- gradient AS compared to the high gradient group (Barasch et al) LOW FLOW LOW GRADIENT AS
  98. 98. Normal-Flow, Low-Gradient AS. Patients with preserved LVEF, normal flow, LG but small EOA (often between 0.8 and 1.0 cm2) are generally patients with moderate-to- severe AS who have an EOA– gradient discordance due to an inherent inconsistency in the guidelines criteria and/or to a small body size. LOW FLOW LOW GRADIENT AS
  99. 99.  However, these patients were an heterogeneous group, likely comprising without distinction patients with paradoxical LF AS and patients with normal-flow, LG AS in conjunction with measurement error, small body size, and/or inconsistencies due to the guidelines criteria.  Among patients with EOA <1.0 cm2, the Paradoxical LF LG AS were found to have the worse prognosis and the Normal flow LG AS the best prognosis. LOW FLOW LOW GRADIENT AS
  100. 100. LOW FLOW LOW GRADIENT AS
  101. 101. Typical Characteristics of the 3 Main Entities of Severe AS LOW FLOW LOW GRADIENT AS
  102. 102. LOW FLOW LOW GRADIENT AS
  103. 103. LOW FLOW LOW GRADIENT AS
  104. 104. CONCLUSIONS LF-LG AS with either normal or reduced LVEF is among the most challenging of situations encountered in patients with VHD. DSE greatly aids risk stratification and clinical decision making in patients with low LVEF, LF-LG AS. LOW FLOW LOW GRADIENT AS
  105. 105. Paradoxical LF-LG AS despite normal LVEF is a recently described entity that has been shown to be associated with a more advanced stage of the disease and worse prognosis. TAVR may eventually prove to be an attractive alternative to surgical AVR in both types of LF-LG severe AS, but this remains to be confirmed by future randomized studies. LOW FLOW LOW GRADIENT AS
  106. 106. Low flow/ Low gradient AS with preserved LVEF is due to intrinsic myocardial dysfunction as evidenced by Speckle Tracking imaging  Valve calcification and serum BNP may be helpful for clinical decision making LOW FLOW LOW GRADIENT AS
  107. 107. LOW FLOW LOW GRADIENT AS

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