Prosthetic Heart Valves Workup

Updated: Feb 18, 2015
  • Author: Eric M Kardon, MD, FACEP; Chief Editor: Richard A Lange, MD, MBA  more...
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Workup

Laboratory Studies

Complete blood count

Hemolysis may cause anemia. In this case, microscopic evidence of hemolysis should be present. A sudden increase in hemolysis may signal a perivalvular leak. [19]

A hematocrit lower than 34% is present in 74% of patients with PVE and is the most common hematologic finding.

A WBC count lower than 12,000 is present in as many as 54% of patients with PVE.

BUN/creatinine levels

Glomerulonephritis and acute renal failure may complicate PVE.

Urinalysis

Hematuria is present in 57% of patients with PVE.

Blood cultures

Culture results are positive in multiple samples in 97% of patients with PVE. Blood cultures should be held for 3 weeks. Multiple blood cultures should be taken.

Prothrombin time (PT)/international normalized ratio (INR)

Recommendations vary as to the target INR. The following is offered as a general guideline, but remember that therapy must be individualized.

Bioprosthetic valves

INR 2-3 for 3 months following implantation; anticoagulation may then be discontinued unless the patient has another indication, such as atrial fibrillation or development of prosthetic valve thrombosis.

Mechanical valves

Aortic valve INR is 2-3; mitral valve INR is 2.5-3.5; Patients with atrial fibrillation should be kept at the higher end of this range. [5] In patients with low hemorrhage risk, low-dose aspirin is recommended in addition to warfarin. [5]

Nontherapeutic values should raise the suspicion of valve thrombosis or systemic embolization.

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Procedures

Certain procedures may cause bacteremia and thereby increase the chance of PVE. The emergency physician must be up to date with the latest prophylaxis guidelines. See Deterrence/Prevention.

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Chest Radiography

An overpenetrated anteroposterior chest radiograph helps to delineate the valvular morphology and whether or not the valve and occluder are intact. In more stable patients, a lateral chest film helps identify the valve position and type.

The following are descriptions of the radiographic appearance of the more commonly seen valves.

Starr-Edwards caged ball valve

The base ring is radiopaque, as is the cage.

There are 3 struts for the aortic valve, and there are 4 struts for the mitral or tricuspid valve

The silastic ball is impregnated with barium that is mildly radiopaque (but not in all models).

Bjork-Shiley tilting disc valve

Although the Bjork-Shiley tilting disc valve has been discontinued, many patients still have these valves implanted.

The base ring and struts are radiopaque. Two U-shaped struts project into base ring.

The edge of the occluder disc is also radiopaque.

Medtronic-Hall tilting disc valve

The base ring is radiopaque.

Radiopaque struts that project into base ring: 3 small ones and 1 large hook-shaped one.

The occluder disc is mildly opaque but often cannot be seen.

Alliance Monostrut valve

The occluder has a radiopaque rim; the base ring and two struts are radiopaque.

St. Jude medical bileaflet valve

Mildly radiopaque leaflets are best seen when viewed on end. These are seen as radiopaque lines when the leaflets are fully open.

The base ring is not visualized on most models. The valve may not be visualized on some radiographs.

CarboMedics bileaflet valves

The valve housing and leaflets are radiopaque and easily visible.

Carpentier-Edwards porcine valve

The tall serpiginous wire support is the only visualized portion.

Hancock porcine valve

The radiopaque base ring is the only visible part in some models.

Other models have radiopaque stent markers with or without a visible base ring.

Ionescu-Shiley bovine pericardial valve

The base ring and wide fenestrated stents are one piece.

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Echocardiography

Acoustic shadowing originating from the components of the prosthetic valve can severely limit the image of the valve itself as well as any pathologic process such as regurgitant streams, vegetations, and thrombosis. This is especially true with valves in the mitral position.

Two-dimensional and Doppler echocardiography, while not as reliable, may demonstrate perivalvular leaks, vegetations, and inadequate valve/occluder movement.

Two-dimensional echocardiography and Doppler echocardiography can detect the presence of acute valvular regurgitation and grade the severity.

Transesophageal echocardiography has emerged as the imaging study of choice in patients with a suspected prosthetic valve complication. This applies especially to prosthetic mitral valves, where transthoracic Doppler is often insensitive. Adequately excluding prosthetic valve regurgitation with a transthoracic echocardiogram is difficult.

In cases where any significant suspicion of valvular stenosis or regurgitation exists, an unremarkable transthoracic echocardiogram is unlikely to be sufficient to adequately rule out a pathologic process.

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Cinefluorography

Cinefluorography may detect impaired occluder movement but often cannot readily determine the etiology.

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Electrocardiography

An atrioventricular (AV) block may indicate the presence of a myocardial abscess. A fever and new AV block is considered PVE until proven otherwise.

AV block may also complicate TAVI, although this usually occurs early in the postoperative period.

Atrial fibrillation is common in mitral valve replacement and may cause hemodynamic compromise.

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