Low Transvalvular Gradient Research Articles

Transvalvular in vivo gradients of the new generation bileaflet heart valve prosthesis St. Jude Medical Regent in aortic position.

By changing the design of the St. Jude Medical Regent prosthesis in shifting both sewing cuff and retaining ring into a completely supra-annular position, the Regent valve has a greater geometric orifice for a given outer diameter. Accordingly, in vitro studies have shown increased effective orifice areas (EOAs) and lower transvalvular gradients. The aim of our study was to determine in vivo transvalvular gradients and EOAs in patients after aortic valve replacement (AVR). We investigated 75 patients at 12 to 21 months follow-up after AVR using transthoracic echocardiography. We determined left ventricular systolic and diastolic function, EOA, and transvalvular peak gradient parameters at rest. Outcomes were assessed using the NYHA classification and functional status. No patient experienced cardiac failure. The majority reported good functional status and good quality of life. Five (6.7 %) late deaths were observed within the surveillance period. At follow-up, 92 % of the patients had improved by at least one NYHA class. Transvalvular peak gradients at rest for patients with Regent valves were 25.4 +/- 7.7 mmHg, 19.2 +/- 4.6 mmHg, 15.6 +/- 5.8 mmHg, 14.6 +/- 5.5 mmHg, and 8.5 +/- 2.5 mmHg; EOAs were 1.38 +/- 0.32 cm2, 1.62 +/- 0.49 cm2, 2.24 +/- 0.83 cm2, 2.63 +/- 0.70 cm2, and 3.28 +/- 0.34 cm2 for valve sizes 19 mm, 21 mm, 23 mm, 25 mm, and 27 mm, respectively. The SJM Regent valve shows excellent in vivo hemodynamics as confirmed by echocardiography. Clinically, 92 % of the patients improved by at least one NYHA class.

Survival after aortic valve replacement for severe aortic stenosis with low transvalvular gradients and severe left ventricular dysfunction

Survival after aortic valve replacement for severe aortic stenosis with low transvalvular gradients and severe left ventricular dysfunction

Evaluation and Management of Patients With Aortic Stenosis

Case presentation: A 66-year-old man is referred to a cardiologist for the evaluation of a heart murmur. The patient claims to be entirely asymptomatic, although his wife notes that he has decreased his physical activity over the past two years because he is “getting old.” At physical examination, his blood pressure was 120/70 mm Hg; pulse, 80 bpm; respiration, 13 breaths per minute; and temperature, 99.0°F. Cardiovascular examination revealed normal central venous pressure. His carotid upstrokes were reduced in volume and delayed in upstroke. Cardiac examination revealed a forceful sustained apical impulse in its normal position. There was a 3/6 late-peaking systolic ejection murmur heard at the right upper sternal border radiating to the neck. The rest of the physical examination was unremarkable. Echo-Doppler evaluation revealed an ejection fraction of 0.60, a left ventricular free wall thickness of 1.3 cm, and a peak transaortic flow velocity of 4.5 m/s. How should this patient be managed? Should he undergo aortic valve replacement now? Should he undergo longitudinal follow-up to monitor progression of his aortic stenosis? Over the past 40 years, diagnostic techniques, substitute cardiac valves, and valve implantation surgery have undergone continued improvement, reducing the risk of the valve replacement and enhancing its benefits. Thus, the risk-benefit analysis of valve surgery has tilted in favor of increasingly early intervention for valve disease. The following is a summary incorporating this concept into the current strategy for managing patients with aortic stenosis such as the one described above. The patient with severe aortic stenosis who presents with symptoms represents the most straightforward management strategy for the disease. Survival is nearly normal until the classic symptoms of angina, syncope, or dyspnea develop.1 However, only 50% of patients who present with angina survive 5 years, whereas 50% survival is 3 years for patients who …

Survival after aortic valve replacement forsevere aortic stenosis with low transvalvular gradients and severe left ventricular dysfunction

ObjectivesWe sought to assess whether aortic valve replacement (AVR) among patients with severe aortic stenosis (AS), severe left ventricular (LV) dysfunction and a low transvalvular gradient (TVG) is associated with improved survival. BackgroundThe optimal management of patients with severe AS with severe LV dysfunction and a low TVG remains controversial. MethodsBetween 1990 and 1998, we evaluated 68 patients who underwent AVR at our institution (AVR group) and 89 patients who did not undergo AVR (control group), with an aortic valve area ≤0.75 cm2, LV ejection fraction ≤35% and mean gradient ≤30 mm Hg. Using propensity analysis, survival was compared between a cohort of 39 patients in the AVR group and 56 patients in the control group. ResultsDespite well-matched baseline characteristics among propensity-matched patients, the one- and four-year survival rates were markedly improved in patients in the AVR group (82% and 78%), as compared with patients in the control group (41% and 15%; p < 0.0001). By multivariable analysis, the main predictor of improved survival was AVR (adjusted risk ratio 0.19, 95% confidence interval 0.09 to 0.39; p < 0.0001). The only other predictors of mortality were age and the serum creatinine level. ConclusionsAmong select patients with severe AS, severe LV dysfunction and a low TVG, AVR was associated with significantly improved survival.

Aortic valve surgery in patients with left ventricular dysfunction

Patient with advanced left ventricular dysfunction and heart failure symptoms, either secondary to severe aortic stenosis and a low transvalvular gradient, or chronic aortic insufficiency are sometimes referred for cardiac transplantation. Now, with improvements in both myocardial protection and better valve prostheses, aortic valve surgery for patients with even the most advanced ventricular dysfunction can be performed with low risk. Copyright 2002, Elsevier Science (USA). All rights reserved.

Aortic stenosis with severe left ventricular dysfunction and low transvalvular pressure gradients: risk stratification by low-dose dobutamine echocardiography

Aortic stenosis with severe left ventricular dysfunction and low transvalvular pressure gradients: risk stratification by low-dose dobutamine echocardiography

The Clinical Significance of QTc Dispersion Measurement for Risk of Syncope in Patients with Aortic Stenosis.

(1) To evaluate the clinical usefulness of QTc dispersion determination in aortic stenosis and (2) to compare the effects of QTc dispersion on the occurrence risk of syncope in aortic stenosis. QT interval dispersion has long been known to be a marker of dispersion of ventricular repolarization and, hence, electrical instability. Additionally, it has been shown that these patients have a propensity to ventricular tachyarrhythmic syncope. The study included 86 patients with aortic stenosis who underwent left-heart catheterization and coronary angiography during investigation of syncope, as well as 30 control subjects. The patients were characterized with regards to the presence or absence of a history of syncope and the severity of aortic stenosis (the degree of peak transvalvular gradient). In addition, QT dispersion measurements were corrected for heart rate according to Bazett's formula and both were measured. QTc dispersion was greater in patients with aortic stenosis than in the control subjects (60 +/- 13 msec vs 38 +/- 12 msec, P < 0.001). Similarly, QTc dispersion was greater in the patients with a history of syncope than in the patients with no history of syncope (68 +/- 12 msec vs 53 +/- 10 msec, P < 0.001). In addition, QTc dispersion values were greater in the patients with a high transvalvular gradient than in the patients with a low transvalvular gradient (65 +/- 12 msec vs 50 +/- 9 msec, P < 0.001). Multivariate logistic regression analysis showed that only an increased QTc dispersion had significant value for the risk of syncope in aortic stenosis. An increased QTc dispersion increases the occurrence risk for syncope in aortic stenosis. These results suggest that high values of QTc dispersion are a sensitive noninvasive marker for determining the risk for syncope in aortic stenosis.

Aortic stenosis with severe left ventricular dysfunction and low transvalvular pressure gradients: Risk stratification by low-dose dobutamine echocardiography

OBJECTIVESWe sought to assess risk stratification by using dobutamine stress echocardiography (DSE) in patients with aortic stenosis (AS) and severe left ventricular (LV) dysfunction.BACKGROUNDFew data are available on risk stratification for valve replacement in patients with AS, LV dysfunction and low transvalvular gradients.METHODSLow-dose DSE was performed in 45 patients (16 women and 29 men; median [quartile range] age in years: 75 [69 to 79]; left ventricular ejection fraction: 0.29 [0.23 to 0.32]; aortic valve area [cm2]: 0.7 [0.5 to 0.8]; mean transaortic gradient [mm Hg]: 26 [21 to 33]). Patients were classified into two groups: group I (n = 32, LV contractile reserve on DSE) and group II (n = 13, no contractile reserve). Valve replacement was performed in 24 and 6 patients in groups I and II, respectively.RESULTSPerioperative mortality was 8% in group I and 50% in group II (p = 0.014). Survival at five years after the operation was 88% in group I. Compared with medical therapy, valve surgery was associated with better long-term survival in group I (hazard ratio for death [HR-D] 0.13, 95% confidence interval [CI] 0.002 to 0.49) and reduced survival in group II (HR-D 19.6, 95% CI 2.7 to 142). The effect of valve surgery on survival remained significant in both groups after adjustment for age, diabetes, respiratory disease and hypertension. Medical therapy had the same effect in both groups.CONCLUSIONSIn patients with AS, LV dysfunction and low transvalvular gradients, contractile reserve on DSE is associated with a low operative risk and good long-term prognosis after valve surgery. In contrast, operative mortality remains high in the absence of contractile reserve.

Association of coronary risk factors with progression of valvular aortic stenosis in older persons

timation” of catheter gradients by Doppler ultrasound in patients with aortic stenosis: a predictable manifestation of pressure recovery. J Am Coll Cardiol 1999;33:1655–1661. 6. Gardin JM, Henry WL, Savage DD, Ware JH, Burn C, Borer JS. Echocardiographic measurements in normal subjects: evaluation of an adult population without clinically apparent heart disease. J Clin Ultrasound 1979;7:439–447. 7. Drexler M, Erkel R, Muller U, Wittlich N, Mohr-Kahaly S, Meyer J. Measurement of intracardiac dimensions and structures in normal subjects by transesophageal echocardiography. Am J Cardiol 1990;65:1491–1496. 8. Skjaerpe T, Hegrenaes L, Hatte L. Noninvasive estimation of valve area in patients with aortic stenosis by Doppler ultrasound and two-dimensional echocardiography. Circualtion1985;72:810–818. 9. Perry GJ, Helineke F, Nanda NC, Byard C, Soto B. Evaluation of aortic insufficiency by Doppler color flow mapping. J Am Coll Cardiol 1987;9:952–959. 10. Pasipoularides A, Murgo JP, Bird JJ, Craig WE. Fluid dynamics of aortic stenosis: mechanisms for the presence of subvalvular pressure gradients. Am J Physiol1984;246:H542–H550. 11. Connolly HM, Oh JK, Schaff HV, Roger VL, Osborn SL, Hodge DO, Tajik AJ. Severe aortic stenosis with low transvalvular gradient and severe left ventricular dysfunction. Result of aortic valve replacement in 52 patients. Circulation 2000;101:1940–1946.

Aortic valve replacement with the Toronto SPV bioprosthesis

The Toronto SPV is a Dacron covered stentless porcine aortic prosthesis used for aortic valve replacement (AVR). We implanted this valve in 53 patients with a mean age of 58 years. The predominant valve lesion was aortic stenosis in 39 patients, insufficiency in 13 and a failed bioprosthesis in one. Six patients also had mitral valve disease and 18 had coronary artery disease. There was one operative death. Patients have been followed for four to 58 months, mean 27 months. There have been two late deaths but neither one was valve related. The actuarial survival at four years was 92% +/- 5%. Two patients required reoperation for reasons other than failure of the stentless aortic valve. There have been no thromboembolic complications. No patient had had infective endocarditis. Doppler echocardiographic assessment of the stentless valve revealed excellent effective valve areas and low transvalvular gradients. A few patients developed mild aortic insufficiency after implantation of the valve, but this problem has been practically eradicated by correct sizing of the prosthesis. AVR with the Toronto SPV provides excellent functional and hemodynamic results. This bioprosthesis seems to be associated with an extremely low rate of valve related complications. These findings justify its continued use, but further follow up is needed to determine its durability.

Outcome and follow-up of aortic valve replacement with the freestyle stentless bioprosthesis

Background. The aim of this study was to determine the morbidity, mortality, and hemodynamics after implantation of the Freestyle stentless bioprosthesis in the aortic position. Methods. A total of 280 patients were operated on from June 1993 to July 1999 as part of a multicenter investigation. Factors influencing hospital mortality and long-term survival were assessed by logistic regression and Cox proportional hazards analysis. Patients were evaluated postoperatively at discharge, at 3 to 6 months, and yearly by clinical examination and color flow Doppler echocardiography. Results. Hospital mortality in this group was relatively high (9.6%). Logistic regression analysis showed that cross-clamp time, age, myocardial infarction, diabetes, left ventricular hypertrophy, coronary artery disease, New York Heart Association class III or IV and female gender were the independent predictive factors. According to the Kaplan-Meier method, the 4-year survival for hospital survivors was 94%. In the multivariate Cox proportional hazard analysis, only coronary artery disease proved to be prognostic. During follow-up, 11 patients developed paravalvular leakage due to prosthetic dehiscence at the side of the noncoronary cusp. Performance of the prosthesis as assessed by echocardiography was excellent. Mean gradient decreased significantly between discharge and follow-up at 3 to 6 months. At 1-year follow-up trivial regurgitation was found in 6 patients (3%) and mild regurgitation in 4 (2%). Regurgitation did not increase with time. The effective orifice area increased significantly from discharge to follow-up at 3 to 6 months. Conclusions. Hospital mortality after implantation of a stentless bioprosthesis was higher compared to conventional prosthesis. A high incidence of prosthesis dehiscence at the proximal suture line was found, which was probably due to technique. Hemodynamic performance up to 3 years showed low transvalvular gradients. There is echocardiographic evidence for reduction of left ventricular hypertrophy and improvement of left ventricular function.

Stentless aortic valve replacement with freestyle or Toronto SPV: an early comparison

Background. Stentless aortic xenograft valves have been developed to overcome the disadvantages of conventional stented prostheses. We have implanted two new aortic bioprostheses: the Medtronic Freestyle and the St. Jude Toronto SPV. Early results are compared. Methods. Forty-four Freestyle valves were implanted using a freestanding total root technique. Fourteen subcoronary Toronto SPV bioprostheses were implanted. Sixty-four percent of both groups (28 of 44 Freestyle and 9 of 14 Toronto SPV) underwent concurrent procedures. Results. Ischemic time was 117 ± 21 minutes for Freestyle and 124 ± 19 minutes for Toronto SPV. There were no operative deaths or valve-related reoperations. Aortic valve area was 1.83 ± 0.51 cm 2 for Freestyle and 1.80 ± 0.51 cm 2 ( p = 0.89) for Toronto SPV. Transvalvular gradient was 8.03 ± 4.09 mm Hg for Freestyle and 12.4 ± 1.82 mm Hg ( p = 0.002) for the Toronto SPV. Aortic regurgitation was not experienced in any Freestyle patients, while Toronto SPV patients were graded as none to trace 79% (11 of 14), mild 14% (2 of 14), and moderate 7% (1 of 14). Conclusions. Aortic valve replacement with the Freestyle and Toronto SPV required equal time for implantation and had equal effective orifice areas. Freestyle had lower transvalvular gradient and less aortic insufficiency without increasing morbidity or mortality.

Severe aortic stenosis with low transvalvular gradient and severe left ventricular dysfunction:result of aortic valve replacement in 52 patients.

The outcome of aortic valve replacement in patients with severe aortic stenosis, low transvalvular gradient, and severe left ventricular dysfunction is not well known. Between 1985 and 1995, 52 patients with left ventricular ejection fraction (EF) < or =35% and aortic stenosis with transvalvular mean gradient <30 mm Hg underwent aortic valve replacement. The mean (+/-SD) preoperative characteristics included EF, 26+/-8%; aortic valve mean gradient, 23+/-4 mm Hg; aortic valve area, 0.7+/-0.2 cm(2); and cardiac output, 3.7+/-1.2 L/min. Simultaneous coronary artery bypass graft surgery was performed in 32 patients (62%). Perioperative (30-day) mortality was 21% (11 of 52 patients). Ten additional patients died during follow-up. Advanced age (P=0.048) and small aortic prosthesis size (P=0.03) were significant predictors of hospital mortality by univariate analysis. By multivariate analysis, the only predictor of surgical mortality was smaller prosthesis size. The only predictor of postoperative survival was improvement in postoperative functional class (P=0.04). Postoperative functional improvement occurred in most patients. Postoperative EF was assessed in 93% of survivors; 74% demonstrated improvement. Positive change in EF was related to smaller preoperative aortic valve area and female sex. Despite severe left ventricular dysfunction, low transvalvular mean gradient, and increased operative mortality, aortic valve replacement was associated with improved functional status. Postoperative survival was related to younger patient age and larger aortic prosthesis size, and medium-term survival was related to improved postoperative functional class.

Aortic Valve Replacement With the Freestyle Stentless Bioprosthesis

Background —Stentless aortic valves were designed to provide a more physiological flow pattern and lower transvalvular gradient, which may have an important bearing on postoperative left ventricular function and remodeling. In this study, we prospectively analyzed the 5-year clinical results with the Freestyle valve (Medtronic, Inc) and its hemodynamic performance by serial echocardiography. Methods and Results —Between January 1993 and August 1997, 95 patients with a mean age of 75 years underwent aortic valve replacement with the Freestyle prosthesis. Sixty-four percent of patients received valves ≤23 mm, and 37% had concomitant coronary artery bypass grafting. Average follow-up was 44±18 months (mean±SD), and echocardiography was performed preoperatively, at discharge, at 3 to 6 months, and annually thereafter. The 30-day operative mortality rate was 3%, with an overall actuarial survival rate of 80±6% (mean±SEM) at 5 years. Of the 10 late deaths, only 2 were cardiac related, thereby yielding a freedom from cardiac mortality of 94±3% after 5 years. No patient required reoperation on the aortic valve for any reason, including structural degeneration, nonstructural dysfunction, or prosthetic valve endocarditis. There were 9 thromboembolic and 3 anticoagulant-related bleeding events, none of which was fatal. The actuarial freedom from valve-related morbidity and mortality was 79±4% at 5 years. Hemodynamically, the mean transvalvular gradient significantly decreased after valve replacement and was reduced further by 41% by 6 months with a corresponding increase in effective orifice area. Left ventricular mass index fell to 75% of the preoperative value by 2 years. Conclusions —The Freestyle stentless valve can be implanted safely in the elderly with excellent midterm clinical results. It has superb hemodynamics in terms of residual transvalvular gradient, effective orifice area, and regression of left ventricular hypertrophy.

Stentless xenograft aortic valves.

Replacement of the diseased aortic valve represents one of the triumphs of cardiac surgery; however, the perfect valve substitute continues to elude surgeons after almost four decades of clinical experience. The characteristics of the ideal valve substitute include the following: central flow capacity, low transvalvular gradient, low thrombogenicity, durability, easy availability, resistance to infection, non-immunogenicity, and easy implantability. The pulmonary autograft first performed by Ross (Lancet 1967, 2:956-958) came closest to achieving these goals, but creates a double valve procedure for single valve disease. Aortic valve replacement (AVR) with homograft aortic valve was introduced by Ross in 1962 (Lancet 1962, 2:487) and Barratt-Boyes in 1964 (Thorax 1964, 19:131-150). Like the pulmonary autograft, homograft AVR results in an excellent hemodynamic outcome but suffers from limitations of graft availability, lack of durability, and difficulty with implantation. Mechanical valves and stented tissue valves allow "off the shelf" easy availability as well as easy implantability. These valves are unfortunately intrinsically obstructed to some extent because of the space occupied by the stent and sewing ring. Stent mounted tissue valves also continue to exhibit limited durability. Stentless xenograft aortic valves have been developed as a compromise between these ends of the valve spectrum to allow excellent hemodynamics and hopefully improved durability while allowing "off the shelf" availability in a variety of standard sizes. We examine the rationale for use of the stentless xenograft aortic valve, the clinical development of this valve, and the surgical techniques of implantation.

Evolving Concepts about Aortic Stenosis

Concepts about the management of aortic stenosis have evolved over the last several years. Concerns about the safety of exercise, positive inotropic drugs, and afterload reduction have been based on the expected exponential relationship of pressure and flow predicted by the Gorlin equation. However, in most patients, even those with severe stenosis, transvalvular pressure gradient increases much less than predicted with increases in cardiac output. Furthermore, data show that exercise testing usually can be performed safely and often provides helpful information about functional status and symptoms. In addition, positive inotropes and afterload-reducing drugs, when initiated cautiously, are often beneficial for these patients. Based on newly available data, physicians are encouraged to wait until symptoms develop before replacing the aortic valve in patients with severe stenosis. Patients with severe aortic stenosis but low transvalvular gradients because of left ventricular dysfunction should have functional testing with dobutamine or nitroprusside. If an increase in flow produces only a minimal increase in transvalvular velocity or pressure gradient, the patient is less likely to benefit from surgery. Risk for noncardiac surgery may not be as high as previously reported in most patients with aortic stenosis; again, functional testing can play an important role in their clinical assessment.

Outcome of Aortic Valve Replacement in Patients With Aortic Stenosis and Low Transvalvular Gradient

Outcome of Aortic Valve Replacement in Patients With Aortic Stenosis and Low Transvalvular Gradient

Outcome of aortic valve replacement in patients with aortic stenosis and low transvalvular gradient

Outcome of aortic valve replacement in patients with aortic stenosis and low transvalvular gradient

Stress echocardiography beyond coronary artery disease.

Doppler echocardiography has become the major diagnostic tool of evaluation of valvular heart disease and the cardiomyopathies because of its ability to provide valuable haemodynamic information accurately and non-invasively. It is therefore ideally suited for haemodynamic stress testing in these patients. In aortic stenosis, dobutamine echocardiography can distinguish severe from non-severe stenosis in patients with depressed left ventricular function, low transvalvular gradients, and a relatively small (flow-related) valve area at baseline. Patients with non-severe aortic stenosis increase cardiac output and valve area with dobutamine infusion while the transvalvular gradient does not change significantly. In severe aortic stenosis, the pressure gradient increases significantly with stroke volume, but valve area does not. In patients who fail to increase stroke volume (absent contractile reserve) and therefore do not show a change in haemodynamics, the severity of the lesion is 'indeterminate'; these patients are characterized by a very poor prognosis. In mitral stenosis, patients can be identified who increase valve area during exercise, which is the fundamental mechanism by which stroke volume can be increased in mitral stenosis. The increase in pulmonary artery pressure during exercise (assessed from tricuspid regurgitant signal) can be dramatically different in patients with comparable resting haemodynamics; therefore exercise echocardiography provides information which cannot be obtained from resting measurements alone and can help to guide medical and surgical therapy. Whether stress echocardiography may be similarly helpful in patients with regurgitant lesions is still a subject of investigation. Exercise Doppler echocardiographic studies following aortic valve replacement (small valves) can identify impairment of systolic and diastolic function indicative of 'valve prosthesis-patient mismatch'. In hypertrophic cardiomyopathy the dynamics of outflow obstruction can be assessed following exercise or pharmacological intervention. In dilative cardiomyopathy, contractile reserve can be assessed by dobutamine echocardiography which may help in evaluating prognosis, guiding heart failure therapy, and monitoring therapy with cardiotoxic chemotherapeutic agents.

The CryoLife-O'Brien composite stentless porcine aortic xenograft valve in 118 patients.

The CryoLife-O'Brien stentless valve is a composite trileaflet porcine aortic valve. It is assembled from 3 non-coronary leaflets and has no foreign material support. It is therefore truly stentless. From December 1992 to January 1996, 118 patients with aortic valve replacement had a CryoLife-O'Brien stentless valve inserted at the Prince Charles Hospital, Brisbane. The mean age was 73 years (range 59-89) and 54% were men. Most patients had aortic stenosis secondary to a calcific degenerative valve. Follow-up is 100% with hematological and echocardiographic studies before discharge, at 6 months, and at 12-18 months. Five deaths (2 early and 3 late) have occurred and morbidity includes 3 strokes, 1 peripheral embolism, 3 perivalvular leaks, and 1 patient with late endocarditis. Valve performance has been good, with low transvalvular gradients and only a trace or no regurgitation in over 95% of patients after 18 months. No structural deterioration or hemolysis has occurred. Echocardiographic surveillance confirms a very effective central orifice. Short-term results show that the overall performance of the CryoLife-O'Brien stentless valve has been very satisfactory, with low mortality and morbidity in this elderly group of patients. The benefits include the absence of prosthetic material, wide leaflet coaptation, and a quick and easy insertion. Long-term anticoagulation is not necessary. It is particularly suitable for elderly patients with a symmetrical aortic root.