Prosthetic Heart Valves Flashcards
Two main types of prosthetic valves are
bioprosthetic valves: biological tissue valves - the animal tissue is chemically treated for tissue preservation and to prevent immunologic reactions
mechanical valves: synthetic valves
Valve repairs with valvular rings are utilized when possible, particularly in cases of ________ repair. Common brand names include:
MV
Carpentier rings
Duran rings
Bioprosthetic Prosthesis
Once implanted, tissue valves are estimated last ________, so this is a big consideration in the selection of process.
10-15 years
Bioprosthetic Prosthesis
Suitable for patients in whom…..
- long-term durability is less important = elderly patients
- chronic anticoagulant is not advised or those at an increased risk for thromboembolism
Mechanical Prosthesis
components of mechanical valves
titanium
carbon compounds
Teflon
Mechanical Prosthesis
advantage vs disadvantage
advantage: durability (last 30+ years)
disadvantage: increased risk of blood clots - constant use of anticoagulant is required and regular monitoring of the prothrombin through labs is also required
Mechanical Prosthesis
suitable for patients in whom….
- children, young adults EXCEPT women in childbearing years
- with renal failure, a small valve annulus, a high re-operative risk, or another reason for anticoagulation i.e. AFib
- requiring Ao Rt replacement due to aortic dissection/severe AR
Bioprosthetic (Tissue) Valves
3 types of Biprosthetic Valves are:
- heterograft (xenograft): transform animal to human
- autograft (self-to-self): transform from one position to another on the same individual
- homograft (allograft): transfer from one human to another
Bioprosthetic (Tissue) Valves
Heterograft (xenograft) biprosthetic valves are further broken down to 2 types, and they are:
stented heterograft
stentless heterograft
Bioprosthetic (Tissue) Valves
Stented heterografts include (2):
Porcine (pig) valve: uses three leaflets mounted on a supporting stent
Bovine (cow) pericardial valve: uses bovine pericardium mounted on a supporting stent
Bioprosthetic (Tissue) Valves
Stenless heterografts were developed to improve _____ and _____ of the bioprosthetic valve; also made from _____ or _____.
- hemodynamics
- durability
- porcine aortic valves
- bovine pericardium
Bioprosthetic (Tissue) Valves
Common brand names for heterograft bioprosthetic valves are:
Medtronic
Carpentier-Edward
Hancock
Edwards Prima Plus
Tronto SPV
Ionescu-Shiley (now discontinue)
Bioprosthetic (Tissue) Valves
Autograft (self-to-self) transfers from one position to another on the same individual. The individual’s ____ valve annulus & trunk are excised and relocated to the aortic valve position; involves repositioning the coronary arteries known as the _____.
pulmonic
Ross procedure
Bioprosthetic (Tissue) Valves
For Autograft (self-to-self), _______ is prepared and utilized as a bioprosthetic heart valve.
fascia lata (thigh muscle covering)
Bioprosthetic (Tissue) Valves
Homograft (allograft) involves transfers from one human to another and is developed from a/n ______ or _______.
It can be stented or stentless and appears very similar to a native valve.
aortic valve
dura mater (brain covering)
Percutaneous Bioprosthesis involves ______ which is a minimally invasive procedure that uses a balloon catheter with a stent-mounted valve crimped its tip.
TAVR (Transcatheter Aortic Valve Replacement): is thead from the femoral artery in th groin, to the aorta, and across AoV. Once the compressed valve is placed over the diseased AoV, the balloon at the end of the catheter is inflated. The expanded valve pushes aside the diseased leaflets and becomes anchored in the valve opening.
TAVR
Assessment of the native valve, calcification, and _annulus diamete_r are crucial prior to deployment. ____ is superior to TTE; however, _____ is the test of choice.
TEE
MSCT (multi-slice computed topography) : a recently developed technique for assessing the function of the heart and coronary arteries non-invasively. Cardiac MSCT uses X-ray beams and a liquid dye to form a 3-D image of the heart and vessels.
TAVR is preferred in _______
high risk surgical patients in attempt to improve their quality of life
Bioprosthetic Valve complications:
- calcification/degeneration with age
- all prosthetic valves are inherently stenotic
- thrombus results from particles that become trapped on the stents or leaflets - might lead to obstruction/stenosis/regurgitation
- PVE (prosthetic vale endocarditis) results from areas of turbulent flow
- perivalvular leak
- dehiscence
- valve annulus abnormality i.e. abscess - leading to dehiscence and perivalvular leak
- physiologic prosthetic regurgitation is common (*single, small, central jet is considered normal)
Bioprosthetic (Tissue) Valves
advantages
- Less obstructive; better hemodynamics
- Fewer complications due to thromboembolism
- May not require anticoagulation
Bioprosthetic (Tissue) Valves
disadvantages
- Less durable than mechanical valves (10-15 years)
- Leaflets may become regurgitant or stenotic due to tissue degeneration and calcification
- Limited availability of homografts
- PVE (prosthetic valve endocarditis) turbulent flow creates a perfect environment for bacteria to latch on faster
- Perivalvular leaks may be caused by dehiscence
- Valve annulus problems such as ring abscess may cause a leak or dehiscence
Bioprosthetic (Tissue) Valves
common stented valve names & their characteristics
- Hancock (porcine or bovine pericardium)
- Carpentier-Edwards
porcine-3 leaflets mounted on a supporting stent
bovine-pericardial valve uses bovine pericardium mounted on a support stent
central flow, trivial/no regurgitation
Bioprosthetic (Tissue) Valves
common stentless valve names (*intended for aortic or pulmonary position) their characteristics
- St. Jude Tronto
- Medtronic Freestyle
- Biocor
- Edwards Prima
- Shiley (discontinued)
improved hemodynamics and durability (porcine & bovine)
porcine, very low mean gradient
Bioprosthetic (Tissue) Valves
Percutaneous Bioprosthetic
TAVR
What is autograft and its characteristics?
- Tissue(valve) transferred or transplanted from one location to another within one’s own body
- Ross procedure – native pulmonary valve sewn into aortic position
- Central flow
- Valve retains ability to grow
- Trivial or no regurgitation
- Very low mean gradient
What is homograft and its characteristics?
- Tissue (valve) transplanted from a human donor
- Typically harvested as a block of tissue (aortic valve, root, and ascending aorta) and trimmed as needed
- Central flow
- Trivial or no regurgitation
- very low mean gradient
Classification and Characteristics Mechanical Valves
What type of valve is this and its characteristics?
Bileaflet Tilting Disk
- Two semicircular disks attached to a rigid valve ring by small hinges
- Flaps pivot open 75o - 90 o
- Two large lateral and one small central orifices create central flow
- Least obstructive/stenotic mechanical prosthesis; allows more laminar blood flow
- Normal leakage volume at margin of central discs and at the periphery between disc and sewing ring.
Classification and Characteristics Mechanical Valves
Most common bileaflet mechaical valve brand names in the US?
St. Jude
*note: CarboMedics, ATS Open Pivot, On-X, and Conform-X are the other brand names
Classification and Characteristics Mechanical Valves
What type of valve is this and its characteristics?
Tilting (single) disk
- Single circular disk rotates within a rigid annulus, with the disk secured by lateral or central metal struts that is mounted on a sewing ring
- creates major & minor orifice
- Disc tilts from 60o - 80o to open a major and minor orifice.
- Low velocity, normal leakage volume; predominantly central with smaller peripheral jets
- Bjork-Shiley disc was the original (discontinued)
Classification and Characteristics Mechanical Valves
Common tilting mechaical valve brand names?
Bjork-Shiley (discontinued)
Medtronic- Hall
Omnicarbon
Lillehei-Kaster
Classification and Characteristics Mechanical Valves
What type of valve is this and its characteristics?
Ball cage (aka: caged ball): Starr-Edwards
- Circular sewing ring with several metal struts that “cage” a small hollow ball
- Rarely used after 1980
- Blood flows around the spherical occlude
- Changes in chamber pressure causes ball to move back and forth
- Least optimal hemodynamics
- Normal closing volume regurgitation
- High profile limits use in patients with small ventricles.
what is valve conduits?
creating a channel for conveying blood flow via mechanical or tissue prosthesis attached to a vessel graft
What is Ross procedure?
a diseased aortic valve is replaced with the person’s own pulmonary valve. A pulmonary allograft is used to replace the patient’s own pulmonary valve.
What is Fontan extracardiac?
direct connection of the SVC to the pulmonary arteries and placement of a tube graft outside of the heart from the IVC to the pulmonary arteries.
Mechanical Valves complications:
- all prosthetic valves are inherently stenotic
- physiologic regurgitation is common *The amount is determined by the make and model
- thrombus results from particles that become trapped and proliferate on the stents or disks
- Pannus ( a fibrous ingrowth of tissue) may lead to regurgitation and/or stenosis
- perivalvular leak - abnormal and may cause for concern
- dehiscence - occurs if the sutures in the sewing ring loosen or break. This causes the valve to rock and may lead to perivalvular leak
- abnormalities of valve annulus i.e. abscess
- PVE
- mechanical failure
- hemolysis - RBCs become damages as they pass through the mechanical valve
A baseline echo should be acquired soon after (within 30 days) the valve repair/replacement. Comparison of serial echo exams is vital to recognize new abnormalities versus pre-existing abnormalities.
T or F ?
T
Prosthetic Valve Dysfunction
stenosis/obstruction etiology
- Gradient varies with : Valve type, Valve size, Anatomic position, Cardiac output
- Etiology of obstruction: Leaflet changes (thickening or calcification), Thrombus or pannus growth, Patient-prosthesis mismatch
What is Perivalvular (Periprosthetic) regurgitation?
- Leakage from outside the sewing ring
- Usually eccentric, high velocity and turbulent flow
- Usually due to valve bed abnormalities or endocarditis
Prosthetic Regurgitation
Thromboembolism: Higher risk with
- Mechanical valves
- Atrial fibrillation
- Large LA
- LV dysfunction
Prosthetic Regurgitation
Hemolysis / anemia caused by
- Mechanical trauma to red blood cells
- Some degree present with all mechanical prostheses
- Periprosthetic leaks, eccentric regurgitant jets, and obstruction are common culprits (cause of defect)