DEFINITON OF ENDOCARDITIS
ENDOCARDITIS….It is the inflammation of the endocardium chiefly involving the valve structure.
TYPES OF ENDOCARDITIS
It may be infective or non-infective. Infective endocarditis may be due to bacteria, fungi or rickettsiae and clinically might be of acute or subacute in its course. The non- infective variety is seen in cases of rheumatic fever, lupus erythematosus, post-myocardial infarction, etc. The acute variety is rare now-a-days because of antibiotics and chemotherapeutic agents. It is caused by streptococci, staphylococci, pneumococci, etc. and may affect a normal valve. The subacute variety is comparatively common and is caused by Streptococcus viridans in 90% of the cases, Other organisms are Streptococcus faecalis, Staphylococcus aeruginosa, Staphylococcus epidermidis, Pseudomonas aeruginosa, Salmonella, Brucella, Haemophilus, Q fever, Candida albicans. Recently of course in most of the cases apart from Streptococcus viridans, nonhaemolytic and microaerophilic streptococci are found. Staphylococcus pyogenes and Staph. albus are seen in narcotic drug addicts and postoperative cases. Infection of normal valve is very rare and seen in drug addicts. Staph. Aureus is the commonest organism. Infection of the previously damaged valves is mostly due to Strep. viridans. However, infection of the prosthetic valves is often due to both coagulase positive and negative staphylococci when infection occurs within 2 months of surgery; but in late onset infections, streptococci are the commonest offending organisms.
1 Rheumatic valve disease: Mitral and aortic valve lesions chiefly, producing regurgitant disease.
- Congenital heart disease e.g. ventricular septal defect patent ductus arteriosus, bicuspid aortic valve, tetralogy of Fallot, etc. In ASD and pulmonary stenosis bacterial endocarditis usually does not occur. But in the former diseases it may occur in presence of mitral stenosis
- Minor surgical procedures in the teeth, tonsils or gums (50% of cases) less often after urinary, pelvic or cardiac surgery.
- Upper respiratory tract infection.
- Prosthetic valves.
Left side of the heart is affected in over 90% of the cases. Right side of the heart is rarely affected-the two common causes are use of unsterile syringe (for intravenous medication, in subjects addicted to drugs) and VSD, SLE may also affect the tricuspid valve (Libmann-Sach’s diseases)
Infective endocarditis does not usually occur in presence of atrial fibrillation, congestive cardiac failure and in syphilitic heart disease.
Onset is gradual
- Malaise, fatigue, lethargy.
- Fever of low grade type is present persistently.
- Pain in the loin due to renal lesion.
- Rarely coma, convulsion, paralysis.
- Features of systemic embolic episodes.
Moderate to several anemia with pallor of a called ‘café-au-lait’ may be present. Temperature is raised. There may be mild jaundice. Pulse shows tachycardia. Clubbing (10%-20 % ) is present and painful. It may disappear after treatment. Petechial haemorrhages (10%-40% ) may be present in the skin and particularly in conjunctivae. These are produced either due to weakness and aneurysmal dilatation of capillaries or due to embolisation. In the latter cases a white centre is present. Splinter or subungual haemorrhages (10%) and Horder’s lines are seen under nails. They are linear in shape (4-5 mm). Jeneway’s lesions (10%) are small erythematous sometimes haemorrhagic non tender lesions in palms and soles due to embolic phenomenon.
Osler’s nodes (10%)
These are semitender nodules 0.5 to 1.5 cm in diameter on the palmar and planter aspects of finger and toe tips caused as results of minute emboli of the cutaneous superficial terminal vessels or by arteritis of smaller vessels with immune complex deposition.
EXAMINATION OF THE HEART
This always reveals some organic disease in the form of congenital or acquired rheumatic heart disease. So, usually a murmur is present (80%). Thus it is a common saying that no murmur, no bacterial endocarditis. But sometimes the signs may be masked due to vegetations on the valve cusps and murmurs are not only changed in their characters but may disappear altogether. After dislodgement of vegetations, murmurs may reappear with their proper characteristics. Signs of heart failure may develop during recovery.
EXAMINATION OF ABDOMEN
Spleen is enlarged (50% cases) and tender. Friction sound may be audible over spleen due to perisplenitis when infarction is present.
EXAMINATION OF KIDNEY
Renal angle may be tender which may be due to renal infarction.
EXAMINATION OF THE NERVOUS SYSTEM
Neurological signs are mostly due to embolic episodes or due mycotic aneurysms. There may be coma, convulsion or hemiplegia. Ophthalmoscopic examination shows yellow elliptical canoe-shaped haemorrhage with a central white spot, called Roth’s spot (10%). This is due to immune complex deposition.
Acute infective Endocarditis
This ually occurs in intravenous drug abusers or following acute suppurative infection, e.g. Pneumonia or Meningitis. Thus it involves normal valves. When tricuspid valve is involved, pulmonary complications and embolic manifestations occur. However, systemic embolisation is rare. The onset is acute and course is more fulminant. Duration is from days to weeks. The common causative organism is Staph. aureus. As valve perforation and destruction or chordal rupture occur quickly, cardiac failure is very common. It is frequently overlooked when it comes at the height or some other suppurative illnesses. At the outset of the disease, murmur may be absent which gradually develops as valve damage progresses. When ventricular septum is involved, AV block with or without syncope may develop. In presence of septic abscess of the myocardium, sudden AV block, Bundle branch block or hemiblock may develop. Prognosis is worse than subacute type.
- Repeated blood culture (two blood cultures daily for 3-5 days) may reveal growth of causative organisms. Blood culture is positive in more than 90% of cases in absence of previous antibiotic therapy. Special culture technique may also be helpful. Culture is negative when infection is due to fungus or for organisms which require special media or do not grow in artificial media.
- Routine blood examination shows hypochromic anemia and high ESR in 90% of cases, CRP is high.
- Urine examination shows albumin, RBC and cast.
- Blood urea and creatinine may be high.
- Electrocardiogram may show non-specific T wave changes and sometimes a prolonged P-R interval apart from changes due to valve injuries.
- Echocardiogram may sometimes show vegetations on the affected valves in 30%-75 % of cases. Transoesophageal echo is more sensitive than two dimensional or M mode echocardiography. Leaflet perforation and periprosthetic fistula formation may be seen also. The sensitivity of TTE is less than TEE (65% in TTE; 90%-100% in TEE).
In cases with early diagnosis prognosis is good. Prognosis is serious if diagnosis is delayed when usually embolic episodes, heart failure, uraemia, severe anemia, etc. usher in.
This is recommended in cases of prosthetic cardiac valves, congenital heart diseases mentioned above, Rheumatic valvular diseases, Mitral valve prolapse syndrome, Aortic valve sclerosis, Hypertrophic cardiomyopathy or when there is history of previous bacterial endocarditis. Prophylaxis is also recommended in the following procedures.
- Dental extraction.
- Dilatation of oesophagus/urethra.
- Cystoscopy, bronchoscopy.
- Vaginal delivery in presence of infection.
- Surgery involving intestine, lung, gall bladder, prostate. urinary tract, uterus.
- Sclerotherapy for varices.
- Cardiac surgery and catheterisation.
- Prolonged intravenous injections.
When culture and sensitivity reports are pending one may start a regime which will act against Staphylo, Strepto and Enterococci. Such a regime is Nafcillin/Oxacillin 1.5 gm every 4 hours plus Penicillin 2-3 million unit every 4 hours plus Gentamycin 1 mg/ kg every 8 hours. But when culture report comes the following plan for particular organism should be started.
For Strep. viridans Penicillin G 3 million units IV every 4 hours for 4 weeks to be given. But the total duration may be curtailed to 2 weeks if Gentamycin 1 mg/kg IM or IV every 8 hours is added. Ceftriaxone 2 gm IM or IV daily for 4 weeks as also effective. When there is allergy to Penicillin, Cefazolin 1 gm IV 8 hourly for 4 weeks or Vancomycin 15 mg/kg 12 Hourly for 4 weeks can be given. In cases with prosthetic valve the duration of therapy must be for 6 weeks.
For Methicillin sensitive Staph. aureus Nafcillin/Oxacillin 2 gm I V every 4 hours for 4-6 weeks is the ideal regimen. In penicillin allergic cases Cefazolin 2 gm every 8 hourS or Vancomycin 15 mg/kg IV every 12 hours may be given. During this treatment with heavy dose of Penicillin there may be pecipitation of heart failure, cerebral oedema, haemolytic anemia and even low grade pyrexia. Relapse may occur in 5%- 10% of cases. In Methicillin resistant cases Vancomycin 30 mg/24 hours IV in two divided doses for 4-6 weeks is good.
Apart from Penicillin in the above dose Inj. Streptomycin or Inj. Gentamycin must be included in the regime to prevent relapse. Ampicillin 2 gm I V 4 hourly kg 12 hourly can also be used.