Michael Scharfschwerdt

A new sinus prosthesis for aortic valve-sparing surgery maintaining the shape of the root at systemic pressure.

PURPOSE We describe a new prosthetic graft aiming to restore normal valve configuration in systemic circulation. In vitro evaluation data and first clinical results are presented. DESCRIPTION The aortic valve consists of three separate leaflets and sinuses of Valsalva interconnected through three straight interleaflet triangles. This shape has important implications on valve function. EVALUATION In vitro tests showed nearly normal hemodynamics, although root distensibility was decreased and bending deformation of the leaflets was increased due to the nonflexibility of the graft material. However, the anatomical shape of the aortic root was well preserved in vitro and also in vivo without contact of leaflets to the prosthesis wall. CONCLUSIONS This new sinus prosthesis maintains normal configuration of the aortic root with three distinct sinuses of Valsalva and straight commissural pillars in systemic circulation. The noncompliant material induces abnormal leaflet bending during systole, but leaflets do not collide with the wall of prosthesis.

Influence of clamp duration and pressure on endothelial damage in aortic cross-clamping.

Aortic cross-clamping during cardiac operations may injure the vessel wall and cause tissue lesions. This experimental study analyses the influence of the intravascular and external pressure and the duration of aortic cross-clamping on endothelial tissue damage. Fresh porcine aortas (n=20) were tested with intravascular pressures from 30 to 80 mmHg. The external clamp pressure, necessary to occlude the aorta, was applied by using the second cog of a commercial aortic clamp and cross-clamping was performed for 1 and 30 min. The observed pressure curves were compared to the histological findings. For occlusion of the aorta, an external pressure of at least 10-fold higher than the intravascular pressure (max. 812 mmHg) had to be applied. After 30 min of clamping, a complete endothelial destruction was observed, irrespective of intra-aortic pressure. The aortic media remained intact. After 1 min clamping, fractions of intact endothelial cells were left, ranging from 40 to 70% at different intra-aortic pressures. These results indicate that endothelial tissue lesions due to aortic cross-clamping are not avoidable, even in moderate clamp application. The duration of aortic cross-clamping but not intravascular pressure is the pivotal factor. The integrity of the aortic media can be preserved if low-force cross-clamping is achieved.

First clinical results with the new sinus prosthesis used for valve-sparing aortic root replacement.

OBJECTIVES Sinuses of Valsalva are important in assuring the physiological function of the aortic valve. This study evaluates short-term clinical results of the reimplantation technique for aortic valve-sparing root replacement using a new prosthesis with three separate sinuses of Valsalva (sinus prosthesis). METHODS Between February 2009 and February 2011, a total of 23 patients (20 m/3 f; mean age 52 ± 14.8 years; range 24-70 years) with aortic root aneurysm underwent aortic valve-sparing procedures according to the David reimplantation technique using the new sinus prosthesis. Eighteen patients had tricuspid and five patients bicuspid aortic valves. All patients received clinical as well as echocardiographic examinations postoperatively (mean 13 ± 9.3 months; 0.3-28 months). RESULTS There was no death and no reoperation of the aortic valve. At latest follow-up, most patients were in New York Heart Association class I (n = 22; 95.7%). In 95.7% aortic valve regurgitation (AR) was 0 or 1+; one patient had AR 2+. Pressure gradients were between the normal range (mean pressure gradient 4.7 ± 1.9 mmHg). Echocardiographic images demonstrate physiological aortic root dimensions and configuration with three separate sinuses of Valsalva without systolic contact of leaflets to the wall. CONCLUSIONS The new sinus prosthesis provides near normal root geometry and hemodynamics in valve-sparing aortic root replacement using the reimplantation technique, applicable for tricuspid and also bicuspid aortic valves.

Failed Valve-In-Valve Transcatheter Aortic Valve Implantation

In 2004, a 68-year-old man received aortocoronary bypass surgery and a 23-mm Hancock porcine bioprosthesis (Medtronic, Minneapolis, Minnesota). Six years later, in January 2011, cardiac re-evaluation was performed due to progressive dyspnea. Invasive angiography showed open bypass grafts and severe

Impact of progressive sinotubular junction dilatation on valve competence of the 3F Aortic and Sorin Solo stentless bioprosthetic heart valves

OBJECTIVE The use of stentless bioprostheses for aortic valve replacement provides excellent haemodynamics; however, these valves bear the potential risk of progressive regurgitation over time. To overcome this disadvantage, a new generation of pericardial stentless prostheses has been developed. This study aims to assess the tolerance of such bioprotheses against progressive sinotubular junction dilatation. METHODS Five specimens of both the 3F Aortic and Sorin Solo stentless bioprotheses (diameter 25 mm) were investigated in a pulsatile flow simulator incorporating a device for gradual expansion of the sinotubular junction diameter. Closing characteristics were obtained by high-speed video imaging and the corresponding regurgitations were determined by ultrasonic flow measurements. The diameters D(R), at which primary distinct regurgitation occurs, were correlated to the original diameters D(A) and expressed as percentage values. RESULTS The highest tolerance against sinotubular junction dilatation was found for the 3F Aortic (156+/-5%) compared to the Sorin Solo (145+/-6%, p=0.0127) bioprothesis. Visualisation of the valves revealed strong leaflet folding at labelled diameter, similar in both valve types. CONCLUSIONS New-generation pericardial stentless bioprotheses provide favourable adaptability to sinotubular junction dilatation, more pronounced for the 3F prosthesis. Whether undue leaflet folding caused by the redundant tissue influences long-term function remains to be established.

Nanocoating with titanium reduces iC3b- and granulocyte-activating immune response against glutaraldehyde-fixed bovine pericardium: a new technique to improve biologic heart valve prosthesis durability?

OBJECTIVES An IgG and granulocyte-activating immune response with secondary dystrophic calcification might be the reason glutaraldehyde (GA)-fixed xenograft valves fail, especially in young patients, who are more immunocompetent than the elderly. Titanium nanocoating on GA-fixed bovine pericardium was tested for its ability to prevent major immunoreactions. METHODS The immune activity of platelets from GA-fixed bovine pericardium with different treatment procedures was evaluated using the blood from 5 human donors: group I (n = 5), GA fixed as the control; group 2 (n = 5), detoxified with 10% citric acid; group 3 (n = 5), 10% citric acid, aldehyde-dehydrogenase, and a physical plasma treatment; and group 4 (n = 5), treated the same as group 3, but with an additional titanium coat 30 nm in thickness. Titanium deposition was visualized using scanning electron microscopy. IgG deposits (iC3b) were shown by immunostaining and documented as colored pixels (red). The pixels were evaluated electronically. Attracted granulocytes (polymorphonuclear leukocytes) were counted in front of the titanium-coated surface. RESULTS IC3b deposits and polymorphonuclear leukocytes within control group 1 were defined as 100%; in group 2, iC3b was 149% ± 34% and polymorphonuclear leukocytes were 89%, in group 3, IC3b was 102% ± 24% and polymorphonuclear leukocytes were 47%; and in group 4, IC3b had decreased to 38.49% ± 21% (P < .05) and polymorphonuclear leukocyte activation had decreased to 6.3% (P ≤ .01). CONCLUSIONS Titanium coating significantly reduced the iC3b and granulocyte activating immune response of GA-fixed pericardium. Therefore, it might prevent relevant immunorejection and increase the durability of GA-fixed bioprosthetic heart valves.

A novel rigid annuloplasty ring for aortic valve reconstruction: an in vitro investigation.

BACKGROUND Remodeling of the dilated valve annulus with a prosthetic ring for repair of valve insufficiency is a well-established concept in mitral and tricuspid valve surgery and may also be suitable for aortic valve reconstruction. A novel rigid aortic annuloplasty ring was tested in vitro. METHODS Ten fresh porcine aortic roots were investigated in a pulsatile flow simulator before surgery (group N), after patch dilatation of the annulus (group D), and after reconstruction using a rigid annuloplasty ring (group R). The ring was designed to (1) prevent contact with the leaflets, reducing the risk of contact injury, (2) be applicable to all valve phenotypes, (3) prevent injury to the conduction bundle, and (4) be implantable from inside the aortic root (subvalvular). For each group pressure gradient, leakage volume, and coaptation height were measured. RESULTS With the annuloplasty ring, regurgitation volume decreased from -8.50 ± 1.91 mL (group D) to -4.75 ± 1.66 mL (group R; p < 0.0003), not different from group N. Coaptation height of the leaflets increased from 0.62 ± 0.08 mm (group D) to 0.77 ± 0.11 mm (group R; p < 0.005), similar to group N. Mean pressure gradient increased from 2.98 ± 0.38 mm Hg (group D) to 3.72 ± 0.40 mm Hg (group R; p < 0.0001). CONCLUSIONS This novel aortic annuloplasty ring has the potential for supporting aortic valve reconstruction by remodeling the subvalvular area.

Automatic measuring of quality criteria for heart valves

Patients suffering from a heart valve deficiency are often treated by replacing the valve with an artificial or biological implant. In case of biological implants, the use of porcine heart valves is common. Quality assessment and inspection methods are mandatory to supply the patients (and also medical research) with only the best such xenograft implants thus reducing the number of follow-up surgeries to replace worn-up valves. We describe an approach for automatic in-vitro evaluation of prosthetic heart valves in an artificial circulation system. We show how to measure the orifice area during a heart cycle to obtain an orifice curve. Different quality parameters are then estimated on such curves.

Automatic In-Vitro Orifice Area Determination and Fluttering Analysis for Tricuspid Heart Valves

Patients suffering from a tricuspid heart valve deficiency are often treated by replacing the valve with artificial or biological implants. In case of biological implants, the use of porcine heart valves is common. To supply patients with the best such xenograft implants, quality assessment and inspection methods for biological heart valves are necessary. We describe initial approaches to automatically testing tricuspid heart valves in-vitro in an artificial circulation system. We use two criteria to judge the quality of the valve, i.e. the evolution of the orifice area during a heart cycle and the fluttering of the valve leaflets in the stream.

Does Undersizing of Transcatheter Aortic Valve Bioprostheses during Valve-in-Valve Implantation Avoid Coronary Obstruction? An In Vitro Study.

Background The transcatheter aortic valve‐in‐valve implantation (TAViVI) is an evolving treatment strategy for degenerated surgical aortic valve bioprostheses (SAVBs) in patients with high operative risk. Although hemodynamics is excellent, there is some concern regarding coronary obstruction, especially in SAVB with externally mounted leaflet tissue, such as the Trifecta (St. Jude Medical Inc., St. Paul, Minnesota, United States). We investigated coronary flow and hydrodynamics before and after TAViVI in a SAVB with externally mounted leaflet tissue (St. Jude Medical, Trifecta) with an undersized transcatheter aortic valve bioprosthesis (Edwards Sapien XT; Edwards Lifesciences LLC, Irvine, California, United States) in an in vitro study. Materials and Methods An aortic root model was constructed incorporating geometric dimensions known as risk factors for coronary obstruction. Investigating the validity of this model, we primarily performed recommended TAViVI with the Sapien XT (size 26 mm) in a Trifecta (size 25 mm) in a mock circulation. Thereafter, hydrodynamic performance and coronary flow (left/right coronary diastolic flow [lCF/rCF]) after TAViVI with an undersized Sapien XT (size 23 mm) in a Trifecta (size 25 mm) were investigated at two different coronary ostia heights (COHs, 8 and 10 mm). Results Validation of the model led to significant coronary obstruction (p < 0.001). Undersized TAViVI showed no significant reduction with respect to coronary flow (lCF: COH 8 mm, 0.90‐0.87 mL/stroke; COH 10 mm, 0.89‐0.82 mL/stroke and rCF: COH 8 mm, 0.64‐0.60 mL/stroke; COH 10 mm, 0.62‐0.58 mL/stroke). Mean transvalvular gradients (4‐5 mm Hg, p < 0.001) increased significantly after TAViVI. Conclusions In our in vitro model, undersized TAViVI with the balloon‐expandable Sapien XT into a modern generation SAVB (Trifecta) successfully avoided coronary flow obstruction.