Lecture 24: Rheumatic Heart Disease Flashcards
what is the pathway of rheumatic heart disease
starts as a sore throat caused by B-haemolytic strep
this can develop into acute rheumatic fever which is due to an immune response which leads to hospitalisation.
- this is notified to the Medical Officer of Health
then rheumatic heart disease can develop which causes damage to the heart valves and other parts of the heart. this is not notifiable
rheumatic heart disease can lead to heart failure
what is acute rheumatic fever?
It is caused by Group A (serogroup) B-haemolytic streptococcal throat infections (streptococcus progenies) which triggers a generalised host immune response
symptoms include:
Arthritis, chorea, erythema marginatum, and subcutaneous nodules
Sydenhams chorea is characterised by emotional lability, uncoordinated movements and muscular weakness
- ARF is a notifiable disease in NZ
how is ARF diagnosed?
there a specific criteria for ARF but it is a clinical diagnosis
what can acute rheumatic fever cause?
ARF can go on to cause Rheymatic Heart Disease
which includes:
- myocarditis
- pericarditis
- involvement of heart valves (thickened or scarred valves)
what happens to the valves during RHD?
most common lesions are to the mitral and aortic valves and include stenosis (narrowing) and regurgitation (backflow)
- Blood comes in from lungs into left atrium
- Left atrium pumps blood into left ventricle
- When ventricle contracts we want blood into aorta (not back into atrium)
- Mitral valve stops blood going back into left atrium
- Valve stop blood going into wrong direction
how is RHD treated?
Rheumatic heart disease leads to a lifelong increased risk of bacterial endocarditis
treatment with antibiotics reduces the risk of bacterial endocarditis and recurrence of ARF (usually is monthly intramuscular injections of penicillin)
antiobiotics may be required at the time of dental, oral and other procedures
- ongoing dental care is essential!
what are the risk factors of RHD?
(this card doesn’t include distal risk factors but make sure to talk about both cards when answering a question)
Preceding GAS (group A strep) infections of throat and skin which may initiate ARF
Environmental risk factors:
- number of social contact
- household crowding and bed sharing
- household resources (e.g. for washing, teeth cleaning, laundry etc)
- housing conditions (e.g. damp and cold)
- environmental tobacco smoke exposure
- exposire to biting insects
- skin injuries
Healthcare factors:
- health literacy and healthcare access
health and nutrition factors;
- health status, oral health status and services, nutrition
social determinants:
- income, education, housing tenure
predisposed host factors:
- demographic, inherited and early development
organism factors:
- molecular typing data
what are the preventions for the RHD pathway?
We want the stages of rheumatic fever from progressing onto the next
for sore throat:
- primary and primordial preventions
- reduce poverty and overcrowding, improve housing
- improve access to health care
- education
- sore throat clinics in schools and neibourhoods
for acute rheumatic fever:
- antibiotic treatments for sore throats
- no vaccine available but it would be good
for rheumatic heart disease:
- identification is important
- penicillin injections monthly
- antibiotic prophylaxis
- register
what are the primary prevention guidelines from the Caridac Society of Australia and New Zealand for Rheumatic fever?
Primary prevention of rheumetic fever:
- primary prevention of acute rheumatic fever in antibiotic therapy of group A streptococcal infections
what are the secondary preventions from the cardiac society and australia and NZ for rheumatic fever?
- month injections of benzylpenicillin for minimum of 10 years after most recent episode of ARF or until age 21+ years (whichever is longer)
- the purpose of this is to prevent colonisation or infection of the upper respiratory tract with group A steptococci and the development of recurrent attacks of RF
- secondary prophlaxis is mandatory for all patients who have had an attack of RF, whether or not they have residual rheumatic valvular heart disease
what screening exists for the steps of the RHD pathway?
Sore throat has throat swabs to identify if the sore throat is bacterial or viral and if it is GAS
Acute rheumatic fever is a clinical diagnosis
Rheumatic heart disease has Ausculation (listening for heart murmurs) and echocardiograms
- NZ HAS NO SCREENING PROGRAMMES FOR ACR-
what is the descriptive epidemiology of rheumatic heart disease?
- don’t confused with acute rheumatic fever-
- RHD is now uncommon in high income countries - globally the incidence of RHD has decreased 9% between 1990 and 2017
- the highest mortality has been seen in oceania (pacific islands), south asia, and central sub-suharan africa
- there is a relatively high prevalence among indigenous populations in New Zealand, australia and USA (shows inequity)
- NZ has high prevalence among pacific people
- female has higher prevalence than males
what does this show?
age-standardised DALYs due to RHD in 2019
south asia has very high DALYs compared to rest of the world
- so does central african republic, zimbabwe, and PNG
what does this show?
age-standardised DALYs due to rheumatic heart disease in 2019 by region
oceania has very high DALYs compared to other regions
so does south asia
australisia is low compared to these
what does this show?
from 1995-2014 there has been an increase in hospitalisation due to RHD
- there has been a decreased in deaths
in 2011 NZ set a NZ Rheumatic fever prevention programme, but we didn’t see the decline that we had hoped for
what does this show
ARF incidence by ethnicty and year, initial hospitalisaition rate per 100,000 5-14 year olds from 1995-2014
- non maori and non pacific has remained very stable and relatively low
maori and pacific ethnicities have seen and increase over the years
- clear highlight of inequities!
what does this show
deprivation vs hospilisations due to ARF and ethnicity
- low deprivation score is associated with higher hospitalisation rates per 100,00
- maori and pacific ethniciteis in lower deciles experience higher hospitalisation rates compared to nonmaori and non pacific
- important inequities highlighted
what does this show
ARF impacts mostly young people!
mainly 6-18 year olds
CVD is normally a disease of aging, but ARF is an exception!
what does this show
- high incidence in auckland, east cape and porirua
corresponds with DHB deprivation data
- highlights that this is a disease of poverty
break down this diagram
the causal pathway of ARF and RHD (blue):
Gas exposure -> GAS infection e.g. pharyngitis, skin infection -> ARF -> RHD -> death
risk factors include:
- fixed host factors e.g. demographics, genetics
- GAS characteristics e.g. emm-type
important risk factors:
- social contact (e.g. household crowding)
- household resources (e.g. washing, bedding)
- housing conditions
- health literacy
- health sector access
- health status
