Prosthetic Heart Valves

Indications for valve replacement:

• valvular stenosis

• valvular regurgitation

  • prolapse

  • perforated leaflet

• aortic dissection w/ severe AI

2 types of prosthetic valves:

• Bioprosthetic

• Mechanical

Types of Bioprosthetic valves:

• Auto-graft

• Homograft / Allograft

• Heterograft / Xenograft

Auto-graft

• a bioprosthetic self-transplant valve

  • valve moved from one position to another within the same pt

  • most common is the “Ross Procedure”

Homograft / Allograft

• bioprosthetic transfer from one human to another

  • valve is removed from another person (after death) and transplanted into the recipient

Heterograft / Xenograft

• bioprosthetic transfer from animal to human

  • tissue from an animal of a different species

    • “hetero” = different

    • “xeno” = foreign

Types of Heterografts / Xenografts:

1. Porcine

2. Bovine

Porcine Xenograft

• Bioprosthetic

• a pig’s AoV is placed on stents and attached to a sewing ring

• most commonly used for MV replacement

  • will have 3 leaflets

• Manufacturers:

  • Hancock

  • Carpentier-Edwards

  • Intact

Bovine Hetrograft

• bioprosthetic

• a cow’s pericardium made into a tri-leaflet valve and mounted on stents and sewing ring

• most commonly used for AoV replacement

• Manufacturers:

  • Carpentier-Edwards

  • Mitroflow

  • Ionescu-Shiley

    • taken off market

Hetrograft AKA:

Xenograft

Ross Procedure

• PV placed in AoV position of same pt

  • auto-graft used for high pressure side

  • homograft used for low pressure side

• usually performed on children

  • must be <40 y/o

Advantage of Ross Procedure:

pt’s valve will grow w/ rest of body

Disadvantage of Ross Procedure:

• if there’s a congenital AoV deformity

  • PV may be deformed too

Complications of Bioprosthetic Valves:

• calcification / degeneration

  • 30% of porcine replaced after 15 years

• dehiscence

  • “bursting open” / falling apart

• regurg

• perivalvular leak / regurg

• stenosis

• infective endocarditis

• thrombus

• pseudoaneurysm

• ring abscess

  • found at annulus

Bioprosthetic valves s/p cardiac surgery:

• septal motion should be paradoxical

• normal septal motion <6 months s/p cardiac surgery may indicate sig MR or AI

Bioprosthetic Valve M-Mode findings:

• usually limited

• used for timing

  • opening/closure of prosthesis

• coarse flutter of leaflets

  • abnormal if seen

2D findings of Bioprosthetic Valves:

• identify:

  • leaflet thickness

    • >3mm is abnormal

  • leaflet motion

  • thrombus

  • calcification

  • dehiscence

  • vegetation

• evaluate LV function

Drawbacks of Mechanical Valves:

• produce an audible click

• increased risk of thrombosis + vegetation

  • using an un-natural and metal material

• limited anticoagulant properties

  • pt required to take Coumadin for life

Benefits of Mechanical Valves:

Will last longer than the patient

Basic parts of Mechanical Valves:

• ball

• cage

  • houses / catches ball

• disc

• strut

  • arm that attaches disc to apparatus

• sewing ring

  • sutures anchor the sewing ring of prosthesis to the native annulus

Types of Mechanical Valves:

• Ball and Cage

• Tilting Disc

• Bileaflet Tilting Disc

Ball and Cage Valve

• mechanical valve

• first type implanted in humans

• not used anymore

  • Starr-Edwards

Tilting Disc Valve

• mechanical valve

• single leaflet

  • Medtronic Hall

  • Omniscience

  • Bjork-Shiley

    • no longer sold in US d/t arm breakage

Bileaflet Tilting Disc Valve

• 90% of mechanical valves used today

  • St. Jude is leading manufacturer

  • Carbomedics

Mechanical Valve M-mode findings:

ring down artifact

Mechanical Valves 2D findings:

• produce shadowing and reverberation

• appearance will vary d/t:

  • angle of insertion by surgeon

  • type of valve used

• TTE can be difficult

  • take extra time to evaluate and image

TEE Evaluation of Mechanical Valves:

• method of choice

• assess regurg

  • may be masked by prosthesis on TEE

• assess anatomic detail:

  • LA appendange

  • thrombus / vege

  • ring abscess

  • pseudoaneurysm

• intraoperative monitoring for:

  • perivalvular leak

  • regurg

  • dysfunction

Symptoms of Mechanical Valve Malfunction:

• may be asymptomatic

• CHF

• fatigue

• SOB d/t pulmonary emboli

Structural changes of Mechanical Valve Malfunction:

• ball or disc may crack

• “Variance”

  • occurs when the ball or disc loses shape and no longer fits within the struts or cage

• strut’s arm has been noted to break off

Mechanical Valve Malfunction may cause:

• thrombus formation

• abscess formation

• endocarditis

• regurg

  • may require surgical correction

• perivalvular leak

• dehiscence

Thrombus formation w/ Mechanical Valve malfunction:

• most common dysfunction of mechanic valves

• usually located at sewing ring

• can cause PE or stroke

• may result in regurg or stenosis

• reason single disc is no longer used

Abscess formation w/ Mechanical Valve malfunction:

• may occur near the sewing ring

• sonolucent center

Endocarditis w/ Mechanical Valve malfunction:

• increased risk b/c valve is foreign

• vegetation may form

• may restrict valve closure

  • causes regurg

• test blood once a month

“Dehiscence” w/ Mechanical Valve malfunction:

• rupture of one or more of the sutures that anchor the sewing ring of prosthesis to annulus

  • “rocking of the valve” appearance

• usually occurs soon after surgery

• may be d/t infection eroding valve

• may be associated w/ abscess formation

Doppler of Prosthetic Valves

• prosthetic valves are mildly stenotic by nature

  • doppler values are different

• degree of obstruction depends on:

  • type

  • size

  • location

• baseline study w/ Dp values

  • important to obtain s/p surgery

    • usually within 30 days

  • make note of best trdx location for accurate d/u exams

• At least 5 beats should be utilized/recorded to obtain hemodynamic Dp measurements

Prosthetic Mitral Valves

• obtain optimal MV Dp signal from apex

  • valve clicks/slaps should be seen

• determine peak velocity

  • >2.5 m/s = abnormal

• determine peak and mean pressure gradients

  • mpg >10 mmHg = abnormal

• determine MVA using P½T method

  • PHT >180 ms = abnormal

  • MVA <1.8 cm² = abnormal

• determine presence + severity of MR

Prosthetic Aortic Valves

• obtain optimal AoV Dp signal

  • pedoff probe

  • usually apical or RPS

• determine peak and mean pressure gradient

  • ppg >45 mmHg = abnormal

  • mpg >15 mmHg = abnormal

• determine AVA using Continuity Equation

  • if LVOT diameter is difficult to determine, use:

    • 2.0 cm for M

    • 1.8 cm for F

  • not accurate w/ co-existent AI

  • some labs may not use AVA

    • use only peak/ mean grad’s

Prosthetic Tricuspid Valves

• tissue valves most com’ly used

  • reduces incidence of thrombosis + pulmonary emboli risk

• Assess for complications

Prosthetic Tricuspid Valve Doppler Findings:

• determine TV Area

  • perform as would MVA

• find peak and mean pressure gradient

• determine presence and severity of TR

Prosthetic Pulmonic Valves

• rarely replaced

  • bioprosthetic used

• assess for complications

Prosthetic Pulmonic Valve Doppler Findings:

• determine peak velocity

  • >2.5 m/s = abnormal

• determine presence + severity of PI

Cloth Covered Rings

• Form of Ring Prosthesis

• used for valve repair w/o replacement

  • usually b/c annulus has been stretched out

• usually Teflon / Dacron material

• always note repair / replacement on Hx

What position are Cloth Covered Rings most commonly used in?

• MV / TV position

  • ring is sutured into position + will add support to annulus

Cloth Covered Rings Echo appearance:

• may be similar to MAC

  • MAC rarely affects AMVL

TAVR / TAVI

• transcatheter aortic valve replacement

• transcatheter aortic valve implantation

• newest procedure for valve replacement

Post TAVR Auscultation

“Honking” murmur → like a goose