Hemodynamic principles of prosthetic aortic valve evaluation in the transcatheter aortic valve replacement era

Evaluating the hemodynamic performance of aortic valve prostheses has relied primarily on echocardiography. This involves calculating the trans-prosthetic valve mean gradient (MG) and aortic valve area (AVA), and assessing for valvular and paravalvular regurgitation in a fashion similar to the native aortic valve. In conjunction with other echocardiographic and nonechocardiographic parameters, MG and AVA are used to distinguish between prosthesis stenosis, prosthesis patient mismatch, pressure recovery, increased flow, and measurement errors. This review will discuss the principles and limitations of echocardiographic evaluation of aortic valve prosthesis following surgical, and transcatheter aortic valve replacement and in comparison to invasive hemodynamics through illustrative clinical cases.     

Pitfalls in Interpreting Bioprosthetic Aortic Valve Pressure Gradients: A Cautionary Tale!

High transvalvular pressure gradients following aortic valve replacement can be caused by several possible mechanisms. We present the case of an elderly woman with an elevated pressure gradient across an aortic valve bioprosthesis in the setting of complete heart block. After consideration of the presence of complete heart block, the hemodynamic profile of the specific prosthesis, and patient‐prosthesis mismatch, only a mild degree of stenosis was found to be attributable to degeneration of the prosthesis. There is no literature quantifying the hemodynamic effect of complete heart block on the pressure gradients across bioprosthetic aortic valves. In the case presented, the transvalvular peak and mean pressure gradients were reduced by 41% and 39%, respectively, following treatment of complete heart block by insertion of a permanent pacemaker.     

Intraoperative and postoperative hemodynamic studies in patients undergoing aortic valve replacement with the Hall-Kaster cardiac disc valve prosthesis.

Intraoperative and postoperative hemodynamic measurements in the first patients to receive the Hall-Kaster cardiac disc valve prosthesis in the aortic position demonstrated the principal hemodynamic pattern of this new mechanical valve. These hemodynamic studies demonstrated favourable transvalvular gradient values and a degree of flow area utilization of the valve orifice which was close to its theoretical maximum. The Hall-Kaster prosthesis thus presented improved flow characteristics in patients undergoing aortic valve replacement, which is considered of particular importance to the patients with a narrow aortic root.     

Hemodynamic characterization of calcified stenotic human aortic valves before and after treatment with a novel aortic valve repair system

BACKGROUND AND AIM OF THE STUDY: The repair of calcified stenotic aortic valves may be a viable alternative to current valve treatments for early-stage aortic valve disease. To date, evaluation of valve repair feasibility on the benchtop has not been performed. A pulsatile flow system for testing intact human aortic valves was developed to perform quantitative hemodynamic and mechanical assessment of a new aortic valve repair approach. METHODS: Intact calcified human aortic valves were divided into two groups with effective orifice area (EOA) > or =2.0 cm2 (group I, n = 6) or <2.0 cm2 (group II, n = 6). All valves were chemically debrided in stages for up to 60 min. A subset of valves in each group was also surgically debrided. At each stage, pre- and post-treatment hemodynamic assessment and video motion analysis were performed in the pulsatile flow system at multiple levels of physiological loading. Mineral removed was quantified using atomic absorption spectroscopy. RESULTS: Progressive removal of mineral with both mechanical and chemical debridement was associated with improved hemodynamic function of calcified human aortic valves. Improvements in EOA of up to 40% and decreases in transvalvular pressure gradient (deltaP) of up to 46% were seen. No clinically relevant increases in regurgitation were observed. CONCLUSION: Repair of stenotic calcified aortic valves using surgical and chemical debridement showed that removal of calcific deposits was directly associated with improvements in valve hemodynamic function. The level of improvement was proportional to the degree of aortic valve stenosis, to the use of surgical debridement, and to the duration of chemical debridement treatment. The study results suggested that aortic valve repair warrants further investigation as an alternative to current valve treatments in patients with early to mid-stage calcific aortic valve disease.     

Echocardiographic and hemodynamic features of severe aortic regurgitation with diastolic opening of the aortic valve

Severe aortic regurgitation may be associated with premature aortic valve opening. Several possible etiologies for this diastolic opening have been suggested. We present a patient with hemodynamic data, M-mode and 2-D echocardiography in the setting of severe aortic regurgitation and diastolic aortic valve opening. Our data lead us to conclude that aortic valve opening in this situation is neither from passive flotation nor dependent on atrial systole. We believe that active ventricular recoil mechanisms can facilitate increases in diastolic ventricular pressure which then can transiently exceed aortic pressure in the setting of severe aortic regurgitation. This hemodynamic observation suggests that the valve opening is an active process.     

Current status of the Beall, Bjork-Shiley, Braunwald-Cutter, Lillehei-Kaster and Smeloff-Cutter cardiac valve prostheses

The Starr-Edwards ball valve prosthesis is generally the standard by which other cardiac valve substitutes are compared. This report reviews information pertaining to several prostheses—the Beall mitral valve and the Bjork-Shiley, Braunwald-Cutter, Lillehei-Kaster and Smeloff-Cutter aortic and mitral valves—considered by some to have specific advantages over the Starr-Edwards valves.

Hospital and late mortality rates after valve replacement are comparable for the four aortic valve prostheses reviewed and depend more on patient selection than on the specific prosthesis utilized. Extensive clinical experience with the Bjork-Shiley aortic valve indicates that this prosthesis offers hemodynamic advantages over ball valve prostheses, especially in patients with a small aortic root. Clinical experience with the Lillehei-Kaster pivoting disc prosthesis has been less extensive, but this model provides theoretical hemodynamic advantages similar to those of the Bjork-Shiley aortic valve prosthesis. Problems associated with cloth wear and the unexpectedly slow rate, in man, of tissue ingrowth into the fabric of the Braunwald-Cutter aortic valve prosthesis have been discouraging, although this prosthesis has been associated with a very low thromboembolic rate in patients receiving anticoagulant therapy. The Smeloff-Cutter aortic prosthesis is hemodynamically similar to the Starr-Edwards prosthesis and has been proved to be a reliable and durable aortic valve substitute over the past several years.

Mortality after mitral valve replacement is also largely influenced by factors other than prosthetic valve design. On the basis of postoperative data, the five mitral valve prostheses reviewed do not appear to have substantial hemodynamic differences. For patients with a small left ventricular cavity the low profile prostheses, such as the Beall, Bjork-Shiley and Lillehei-Kaster, may be advantageous.

Most available evidence indicates that patients receiving aortic or mitral valve prostheses should be given anticoagulant therapy postoperatively.     

Pseudocoarctation of the aortic arch associated with bicuspid aortic valve lesion: is it a surgical entity?

Three patients with bicuspid aortic valve lesion associated with pseudocoarctation of the aortic arch are presented. At operation, 2 had a bicuspid calcified stenotic aortic valve, and one a bicuspid non-calcified incompetent aortic valve. All required replacement of the diseased aortic valve. The pseudocoarctation was not corrected because it caused no hemodynamic abnormality.     

Interpretation of cardiac pathophysiology from pressure waveform analysis: percutaneous balloon valvuloplasty.

The hemodynamic findings of aortic, mitral and pulmonary balloon valvuloplasty serve to identify classical valvular lesions and their responses to graded or abrupt catheter dilation techniques. The production of mild insufficiency after valve dilation is generally well tolerated. Severe valvular insufficiency produces the expected hemodynamic alterations, but acute decompensation may be witnessed over brief periods of time. The use of extra stiff guidewires across dilated valves, especially the aortic valve, may also produce an exaggerated hemodynamic picture of insufficiency. Although gradients may be reduced, the effect of valve dilation on aortic valve area is generally small. A discussion of factors influencing valve area calculations will be the subject of a future "Rounds."     

Postoperative disc entrapment following cardiac valve replacement--a report of ten cases

The sudden jamming of a prosthetic valve disc is one cause for postoperative hemodynamic deterioration. This complication occurred in 10 instances (2% of disc valves implanted), resulting in 4 fatalities. In 6 patients the disc entrapment was a complication following mitral valve replacement, and in 4 others the malfunction followed aortic valve surgery. The entrapment of the disc occurred on the second postoperative day in 3 patients. Two of these were due to an unresected chordal strand becoming wedged between the disc and valve rim of a Bj?rk-Shiley mitral prosthesis and resulted in death. In the third patient, the aortic valve disc became attached to the Bj?rk-Shiley composite aortic graft following the repair of an aortic dissection. A firm blood clot had formed between the graft and the oversewn aortic wall. This patient recovered after cardiopulmonary resuscitation and subsequent reoperation. The remaining cases developed while the patients were still either on the operating table or in the recovery room. The mechanisms of the disc entrapments are presented and the significance of an early correct diagnosis and urgent surgical correction is underlined.     

Heart failure and "inoperable" aortic stenosis: staged balloon aortic valvuloplasty and aortic valve bypass

The prognosis for patients with symptomatic aortic stenosis is poor but is improved significantly by surgical aortic valve replacement. Unfortunately, many patients are refused surgery because of age, comorbidities, and hemodynamic instability. This report describes the successful use of balloon aortic valvuloplasty as a bridge to aortic valve bypass surgery (apicoaortic conduit) in an elderly patient with class IV congestive heart failure and severe left ventricular systolic dysfunction as a consequence of aortic stenosis who was not a candidate for traditional surgical valve replacement.     

Immediate results and long-term follow-up after repeat balloon aortic valvuloplasty

Balloon aortic valvuloplasty (BAV) was performed in 219 elderly patients with aortic stenosis between December 1985 and April 1990. Forty-three patients underwent repeat BAV for symptomatic restenosis of the aortic valve 13±8 mo following initial BAV. To evaluate the outcome following initial and repeat BAV, hemodynamic results were analyzed according to the following subgroups: BAV 1-initial BAV for all patients (n = 219); BAV 1/1-initial BAV in those who had only one BAV (n = 176); BAV 1/2-the initial BAV in those who had repeat BAV (n = 43); and BAV 2-repeat BAV (n = 43). The mean age of patients undergoing BAV 2 was 82±6 yr compared to 78±10 yr for all patients undergoing BAV 1 (p = .01). At the time of BAV 1 there was no difference in baseline or post-valvuloplasty aortic valve area (AVA) or peak aortic valve gradient (AVG) for patients having BAV 1/1 compared to those having BAV 1/2. However, for patients having repeat BAV, although the magnitude of the hemodynamic improvement of BAV 1/2 (AVA increased from 0.6 to 0.9 cm², AVG decreased from 65 to 34 mm Hg, p<.001) was similar to the magnitude of the hemodynamic improvement of BAV 2 (AVA increased from 0.5 to 0.8 cm², AVG decreased from 65 to 34 mm Hg, p<.001), the baseline AVA (0.5 cm² at BAV 2 vs. 0.6 at BAV 1/2) and the post-valvuloplasty AVA (0.8 cm² at BAV 2 vs. 0.9 at BAV 1/2) were significantly smaller (p<.004). There were no major complications in patients undergoing repeat BAV. Median event-free survival was 12 mo after initial BAV and 8 mo after repeat BAV (p = .09). In conclusion, repeat BAV results in similar immediate hemodynamic improvement and event-free survival compared to initial BAV. However, baseline aortic valve area and gradient prior to repeat BAV are significantly worse than those prior to initial BAV, suggesting that balloon-induced injury to the aortic valve may offer only a temporary hiatus from the natural history of aortic stenosis.     

Transient acute severe aortic regurgitation complicating balloon aortic valvuloplasty

Transient, acute severe aortic regurgitation documented by hemodynamic and Dopplerechocardiographic assessment was observed in an elderly woman immediately following balloon aortic valvuloplasty for critical aortic stenosis. Aortic regurgitation responded to medical therapy and resolved within 24 hr. Potential mechanisms are discussed. We suspect that an oversized balloon to aortic ring area stretched the annulus, separating the valve cusps and resulting in severe regurgitation, which rapidly normalized.     

The fate of aortic valve homografts 12 to 17 years after implantation

Results of long-term follow-up of an early cohort of patients receiving aortic valve homografts for aortic stenosis and aortic insufficiency are presented. All patients were operated upon by a single surgeon from 1966 to 1971. Eighty-three patients underwent insertion of 85 homograft aortic valves. Homografts were sterilized with either betapropiolactone (39 valves) or gamma irradiation (41 valves) and were inserted following storage in nutrient medium (16 valves) or after cryopreservation (51 valves). All homograft valves were sutured in the subcoronary position using a freehand technique. There was a 55 percent 15-year actuarial patient survival and a 16 percent 15-year actuarial homograft survival in this cohort. Homograft valve failure occurred gradually allowing the patients to be observed until they developed hemodynamic compromise at which time elective valve replacement was performed.     

Radiation-associated valvular disease

The prevalence of radiation-associated cardiac disease is increasing due to prolonged survival following mediastinal irradiation. Side effects of radiation include pericarditis, accelerated coronary artery disease, myocardial fibrosis and valvular injury. We evaluated the cases of three young patients with evidence of significant valvular disease following mediastinal irradiation. One patient underwent the first reported successful aortic and mitral valve replacement for radiation-associated valvular disease (RAVD) as well as concurrent coronary artery revascularization. A review of the literature revealed 35 reported cases of RAVD, with only one successful case of valve replacement that was limited to the aortic valve. Asymptomatic RAVD is diagnosed 11.5 years after mediastinal irradiation compared with 16.5 years for symptomatic patients, emphasizing that long-term follow-up is important for patients receiving mediastinal irradiation. This study defines a continuum of valvular disease following radiation that begins with mild asymptomatic valvular thickening and progresses to severe valvular fibrosis with hemodynamic compromise requiring surgical intervention.     

Transcatheter aortic valve in valve implantation with bioprosthetic valve fracture

Valve‐in‐valve transcatheter aortic valve replacement (VIV TAVR) has emerged as a preferable option for high surgical risk patients requiring redo aortic valve replacement. However, VIV TAVR may restrict flow, especially in small native aortic valves. To remedy this, bioprosthetic valve fracture has been utilized to increase the effective orifice area and improve hemodynamics. We present three cases in which bioprosthetic valve fracture was used to increase hemodynamic flow in VIV TAVR procedures.     

Percutaneous closure of complex paravalvular aortic root pseudoaneurysm and aorta-cavitary fistulas

Native aortic valve or its prosthetic valve endocarditis can extend to the adjacent periannular areas and erode into nearby cardiac chambers, leading to pseudoaneurysm and aorta-cavitary fistulas respectively. The later usually leads to acute cardiac failure and hemodynamic instability requiring an urgent surgical intervention. However rarely this might pass unnoticed and the patient might present later with cardiac murmur. Percutaneous device closure of aortic pseudoaneurysm, ruptured sinus of Valsalva aneurysm, aorta-pulmonary window, paravalvular leaks, and aorta-cavitary fistula have been reported. We present a 59-year-old female who developed a large aortic root pseudoaneurysm with biventricular communication aorta-cavitary fistulas presenting late following aortic prosthetic valve endocarditis. She underwent successful percutaneous device closure of her pseudoaneurysm and aorta-cavitary fistulas using two Amplatzer Duct Occluders. This case illustrates a challenging combination of aortic root pseudoaneurysm and biventricular aorta-cavitary fistulas that was successfully treated with percutaneous procedure.     

Emergent use of retrograde left ventricular support in patients after transcatheter aortic valve replacement

Transcatheter aortic valve replacement (TAVR) is currently a therapeutic alternative to open aortic valve replacement for high‐risk patients with severe symptomatic aortic valve stenosis. The procedure is associated with some life‐threatening complications including circulatory collapse which may require temporary hemodynamic support. We describe our experience with the use of the Impella 2.5 system to provide emergent left ventricular support in cases of hemodynamic collapse after TAVR with the Edwards SAPIEN prosthesis.© 2012 Wiley Periodicals, Inc.     

Immediate results and long-term follow-up after repeat balloon aortic valvuloplasty.

Balloon aortic valvuloplasty (BAV) was performed in 219 elderly patients with aortic stenosis between December 1985 and April 1990. Forty-three patients underwent repeat BAV for symptomatic restenosis of the aortic valve 13 +/- 8 mo following initial BAV. To evaluate the outcome following initial and repeat BAV, hemodynamic results were analyzed according to the following subgroups: BAV 1--initial BAV for all patients (n = 219); BAV 1/1--initial BAV in those who had only one BAV (n = 176); BAV 1/2--the initial BAV in those who had repeat BAV (n = 43); and BAV 2--repeat BAV (n = 43). The mean age of patients undergoing BAV 2 was 82 +/- 6 yr compared to 78 +/- 10 yr for all patients undergoing BAV 1 (p = .01). At the time of BAV 1 there was no difference in baseline or post-valvuloplasty aortic valve area (AVA) or peak aortic valve gradient (AVG) for patients having BAV 1/1 compared to those having BAV 1/2. However, for patients having repeat BAV, although the magnitude of the hemodynamic improvement of BAV 1/2 (AVA increased from 0.6 to 0.9 cm2, AVG decreased from 68 to 34 mm Hg, p less than .001) was similar to the magnitude of the hemodynamic improvement of BAV 2 (AVA increased from 0.5 to 0.8 cm2, AVG decreased from 65 to 34 mm Hg, p less than .001), the baseline AVA (0.5 cm2 at BAV 2 vs. 0.6 at BAV 1/2) and the post-valvuloplasty AVA (0.8 cm2 at BAV 2 vs. 0.9 at BAV 1/2) were significantly smaller (p less than .004).(ABSTRACT TRUNCATED AT 250 WORDS)     

Association of aortic dilation with regurgitant, stenotic and functionally normal bicuspid aortic valves.

To determine whether aortic root dilation associated with a bicuspid aortic valve occurs independently of valvular hemodynamic abnormality, aortic root dimensions were measured by two-dimensional echocardiography in 83 adults with a functionally normal (n = 19), mildly regurgitant (n = 26), severely regurgitant (n = 27) or stenotic (n = 11) bicuspid aortic valve and compared with findings in normal subjects matched for age and gender. Aortic root measurements were made at four levels: anulus, sinuses of Valsalva, supraaortic ridge and proximal ascending aorta. Seventy-one percent of patients with a bicuspid aortic valve were men. When compared with control subjects, all hemodynamic subgroups showed a significantly larger aortic root size at three levels: sinuses of Valsalva, supraaortic ridge and proximal ascending aorta (p less than 0.05 to p less than 0.001). The prevalence of aortic root enlargement among all hemodynamic subgroups ranged from 9% to 59% at the level of the anulus, 36% to 78% at the sinuses, 47% to 79% at the supraaortic ridge and 50% to 64% in the ascending aorta. Thus, there is a high prevalence of aortic root enlargement in patients with a bicuspid aortic valve that occurs irrespective of altered hemodynamics or age. These findings support the hypothesis that bicuspid aortic valve and aortic root dilation may reflect a common developmental defect.