Infective Endocarditis

Introduction

Infective endocarditis (IE) is an infection of the internal lining of the heart, mostly affecting its valvular structures.
Its presentation is non-specific meaning its often missed.
The prognosis of IE is poor because infection easily spreads to other organs or parts of the heart.

Infection develops on valvular surfaces which have sustained endothelial damage. This serves as a great nidus for infection; however, colonisation also induces further damage and thrombus formation.

This is why it can eventually mature into a growing infected vegetation.

Classification

Native Value Endocarditis

Caused by 3 key main pathogens:

Staphylococcal, which is the most common overall and associated with hospital acquired infection
Viridans group Streptococci, which is associated with community acquired IE
Enterococci

Prosthetic Valve Endocarditis

This is divided into:

Early infection which has a poor prognosis
Late infection defined as 1 year post implantation.

Right-sided Endocarditis

This is special because its rarer and highly associated intravenous drugs and Staph aureus.

The diagnosis can be made using the Modified Duke Criteria.

There are 2 parts to the Major Criteria:

Positive blood cultures in 2 separate collections
Endocardium involvement e.g. a positive echo showing vegetation.

There are 5 Minor Criteria that form the FIVER acronym:

Fever
Immunological phenomena like Osler’s nodes
Vascular phenomena like Janeway’s lesions
Infection evidence with a single positive culture
Risk factors for the disease like IV drug use.

The criteria is fulfilled if you have 2 major or all the minor criteria.

Management ideally requires a dedicated multidisciplinary endocarditis team including an infectious diseases physician, a cardiologist, and a cardiac surgeon.

IV antibiotics are the mainstay of treatment. Beta lactams are frequently used. Additionally, gentamicin helps cover for Gram-negative sepsis.

Cardiac surgery is commonly needed and indicated if it causes heart failure, significant vegetation or emboli.

History:

Inquire about features of heart failure like dypnoea on exertion, orthopnoea, and paroxysmal nocturnal dyspnoea. Look for features suggestive of emboli like stroke symptoms, chest pain and headache. Finally, constitutional symptoms like night sweats, malaise and fatigue.

Physical Examination:

On examination, specifically look for your patient’s MOJO.

Murmurs, which are found in up to 85% of patients

Osler nodes, or the ouchy nodes because they're the painful lesions on the fingers

Janeway lesions, which are painless plaques on the palms, and finally

Odd Splinters in the nails, referring to splinter haemorrhages