Category Archives: Cardiology

SVT

Supraventricular tachycardia – where abnormal rhythm initiated above atrioventricular node, so narrow complex (with normal conduction down bundles of His). Typically rate over 220, with abrupt onset (can be inferred from history).

ECG showing SVT and effect of adenosine
SVT showing effect of adenosine

Accessory pathway that bypasses the AVN is the usual reason, esp infants, but nodal reentrants quite common in older kids. Get a 12 lead before doing anything, unless absolutely impossible.

An accessory pathway usually has a delta wave (upsloping PR). If retrograde conduction, then inverted P wave seen immediately after the QRS. If a nodal reentrant, P wave is subsumed into QRS complex.

If decompensated then synchronised cardioversion (under IM/IN ketamine).

Vagal manoeuvres do work, such as doing a valsalva manoeuvre (get child to blow through straw!), bag of icy water held to face (count to 5). Older kids can stand on their hands! Carotid sinus massage is the least effective.

But best to go straight to IV adenosine if access available. Adenosine causes sinus arrest, which feels terrifying for child. Within a few seconds, wears off and spontaneous return of rhythm, hopefully a normal one. Can also induce wheeze. Give in antecubital fossa, so as close to heart as possible.

Starting dose lower if over 1yr. Then increase by 50-100mcg/kg each time. If adenosine doesn’t work:

  • check max dose (different for neonates and older children, 12mg max)
  • check rapid bolus and flush
  • check diagnosis is correct.

Digoxin is good for babies and infants but needs 2 loading doses 6 hours apart, and you may not get a result until then. Propanolol is contraindicated in asthma. Amiodarone should be used before 3rd shock. Verapamil is contraindicated under 1 year as can cause arrest.

Prognosis

SVT usually settles down by 6-12 months but may recur around the age of 8yrs. Onset outside infancy will probably not resolve spontaneously. Prevention needs to be discussed: some families will be happy just treating episodes as they occur. Otherwise use digoxin in infancy to prevent, propanolol later.

Rare forms

Rare forms:

  • Permanent form of Junctional Reciprocating Tachycardia (PFJRT) – chronic SVT, so may go unrecognised and then cause cardiomyopathy. The accessory pathway is resistant to DC shock and adenosine. Inverted P wave seen.
  • Ectopic atrial tachycardia – due to an ectopic focus. May also be chronic. Demonstrates warm up and slow down in rate, whereas others tend to have fixed rate. First degree block seen. Resistant to DC shock and adenosine.
  • Atrial flutter usually seen only in congenital heart disease but does occur in neonates with normal hearts! In which case it tends not to recur. Ventricular rate divides neatly into 300.
  • Atrial fibrillation – needs anticoagulation before DC conversion so control rate first with digoxin while loading warfarin.

Fabry’s disease

Alpha-galactosidase defect, one of the lysosomal storage disorders, with accumulation in various tissues.

X-linked but females get disease, so not correct to call them carriers.

Classically, “pain attacks”, affecting the extremities. In the abdomen, can mimic appendicitis. Due to accumulation in nerves. Since nothing to really see on examination, easily misdiagnosed as functional.

Other features:

  • Renal impairment and failure.
  • Angiokeratomas – a more specific feature, but not always present, and seen in other lysosomal disorders.
  • Corneal changes
  • Cerebrovascular and cardiac problems

[Omim]

Hypertension

In children under 10, high BP is usually secondary to an underlying disease or condition. Primary hypertension increasingly recognised in older, obese children.

Do repeated measurements, ideally automated home BP monitoring, before diagnosing hypertension. Check manually as well as with automated device. Beware “white coat effect”, even if not clearly anxious.

Use appropriate cuff size – cuff should cover at least 75% of the upper arm from the acromion to the olecranon (should be sufficient space at the antecubital fossa to apply stethoscope!) .  An inappropriately small cuff will overestimate BP.

Long list of causes, so follow the clues.

Family history important, of course.

Examination

So needs thorough history and examination, including:

  • Fundi
  • Bruits, radiofemoral delay
  • Neck for goitre

Complications

Consider then end organ effects –

  • Proteinuria, high creatinine
  • Retinopathy
  • Left ventricular hypertrophy, cardiac failure
  • Abnormal tone and reflexes, cranial nerve deficits if severe

Management

Depends on how high, whether other risk factors (diabetes, chronic kidney disease), symptoms and evidence of end organ damage.

Initially low salt diet, weight loss (if obese).  Remember other morbidities related to obesity.

Acute hypertension might need frusomide and/or nifedipine.

Long term treatment is only going to be started if no improvement with lifestyle measures. Target BP depends on risk factors, as above.

[2016 European Society for Hypertension guidelines]

Cardiomyopathy

Uncommon, but often tricky to recognise, potentially lethal.

Multiple causes:

  • Viral esp enterovirus
  • Genetic
  • Metabolic
  • Autoimmune
  • Chagas, Diphtheria important in other countries

Presents with anorexia, vomiting, breathlessness. Can be abdo pain (gut ischaemia?). Chest pain unusual, young children may struggle to describe anyway. Syncope or palpitations if arrhythmia. Confusion and agitation if acidotic.

Heart will eventually enlarge but may not be apparent initially. Inappropriate tachycardia; breathlessness with clear lungs and CXR (not always acidosis), esp with exertion. Hypotension.

May be new murmur eg MR if heart enlarged.

Small complexes, ST changes, q waves on ECG. Troponins may be high, LFTs deranged, renal impairment as secondary effects.

Echo diagnostic.

Start inotropes (peripheral possible). Various mechanical aids eg Berlin Heart, ECMO.

Alagille Syndrome

Autosomal dominant condition (70% sporadic) with characteristic facies, biliary hypoplasia, vertebral and cardiac abnormalities. JAG1 gene.

Paucity of intrahepatic bile ducts so typically prolonged jaundice, but depending on how many ducts, may not be obvious in first few months. Jaundice gradually improves, but only minority clear completely. 30% progress to cirrhosis.

Posterior embryotoxon (white ring at periphery of cornea) is a clue, but seen in 10% of normal population so not specific.

Cardiac includes pulmonary stenosis, Tetralogy of Fallot.

Facies: broad forehead, triangular face, deepset eyes, long nose with bulbous tip.

Butterfly vertebrae characteristic (asymptomatic – see on chest x-ray).

Other:

  • Renal Tubular Acidosis, renal cysts
  • Growth failure
  • Pancreatic insufficiency

Murmurs

An added sound heard when listening with a stethoscope, distinct from heart sounds or other clicks or snaps.

Can indicate a structural abnormality.  But can be heard in normal hearts too, esp kids.

Still’s murmur

Or “innocent” murmur.  Characteristic vibratory, crescendo-decrescendo sound, loudest along left sternal border.  Never louder than grade 3.  Typically gets quieter when child stands up (you would not expect a murmur caused by a structural abnormality to change).

Venous hum

Another innocent one, a rumble heard in the upper chest, disappears when lying down, or when neck turned or neck veins occluded gently.

Pulmonary flow murmur

Pulmonary valve closest to anterior chest wall, which might explain why you sometimes hear this.  Might be confused with pulmonary stenosis or subaortic membrane.

Prolonged QT interval

An abnormal finding on ECG.

QT interval changes with heart rate, so usually calculated as corrected QT (QTc), where average QT is divided by square root of RR interval (ie 1 second, if heart rate 60).

Associated with dysrhythmia, especially torsades de pointes (polymorphic ventricular tachycardia).

Seen with:

  • Genetic predisposition – Long QT syndrome
  • Certain drugs – antipsychotics (eg chlorpromazine, quetiapine), antiarrhythmics (!?), tricyclic antidepressants (eg amitriptyline), other antidepressants (eg citalopram, venlafaxine), antihistamines (terfenadine, but also loratadine, diphenhydramine, astemizole), macrolides, quinine.

Cerebral Arteriovenous malformation (AVM)

Present with hydrocephalus or else cardiac failure in neonatal period. Clue is that heart is structurally normal!

Life time risk of haemorrhage is high, presenting with headache or seizure.  Annual rate about 6%.  Focal neuro signs rare prior to haemorrhage!  Risk slightly higher in deep locations eg basal ganglia.

Once haemorrhage has occurred, risk of further haemorrhage increases significantly.  Microsurgery, radiosurgery or embolization techniques used alone or in combination.

 

Rheumatic fever

Rare in developed world now, still common in underdeveloped world, or at least in underdeveloped communities eg Aboriginal Australians.  Prob also genetic susceptibility.

Caused by Group A streptococcus.  Important cause of acquired heart valve disease.  Can recur.

Probably cross reactivity between specific Group A strep M proteins and human tissues.

Diagnosis

Jones criteria:

  • Major
    • Carditis eg new murmur.  Mitral most commonly, classically apical blowing pan-systolic.  Aortic next most common.
    • Arthritis esp large joints.  Migratory.
    • Subcutaneous nodules – these are the most uncommon major criterium.  Typically over extensor surfaces of joints, 0.5-2cm, symmetrical.
    • Sydenhams chorea
    • Erythema marginatum – not specific to rheumatic fever.  Serpiginous or annual eruption, can look similar to erythema multiforme. Provoked by warmth eg bath.  Non pruritic.
  • Minor
    • Fever
    • Arthralgia
    • Prolonged PR interval on ECG
    • Elevated CRP/ESR
  • 2 major or 1 major plus 2 minor, plus confirmation of group A streptococcal infection eg positive culture, high ASO titre sufficient for diagnosis.

Note that initial infection may be subclinical eg pharyngitis, erysipelas. Symptoms of rheumatic fever develop 10 days to several weeks later. Chorea can appear months later.  Low threshold for echo as carditis can also be subclinical.

UFMG rating scale for assessing function.

Treatment

Antibiotics – Treat with penicillin,  this does not however affect clinical course but hopefully prevents further spread of that particular bug. Traditionally single dose intramuscular Penicillin G Benzathine.

NSAIDs for joint pain.  Usually dramatic response, if not then reconsider diagnosis!

Valproate for chorea, possibly steroids – see Sydenham’s.

Aspirin and/or Steroids for carditis, but not much evidence.  Diuretics, ACE inhibitors for cardiac failure.

Long term treatment

Recurrence with progression of valve damage is the main concern, and well recognized.  Regular intramuscular penicillin (benzathine pencillin G) every 2-3 weeks has the lowest recurrence rates but oral penicillin V more acceptable.  Erythromycin or cephalexin if allergic.

WHO recommendations:

  • Rheumatic fever without carditis: 5 years after last attack or until age 18 (whichever is longer)
  • Rheumatic fever with carditis but without residual disease: 10 years after last attack or until age 25 (whichever is longer)
  • Residual valve disease or valve replacement: lifelong

American heart association guidelines vary slightly.

Familial Hypercholesterolaemia

Usually LDL receptor gene mutations (on liver, for removing lipids from blood). One Apo-B mutation (on LDL) identified.  Least common is PCSK9 mutation – higher degradation of receptor, most severe.

If normal BMI, elevated LDL, autosomal dom inheritance, normal TFTs then 95% LDL receptor defect.

If one sibling has a LDL double that of another sibling, 99.8% LDL receptor mutation.

Highly heterogeneous in UK, over a 1000 mutations.

Estimated 1/500 in most countries [but in Denmark found 1/137, Holland has found 1 in 232].  So prob only 12% of cases identified in UK, even less in young individuals!

DNA screening cf lipid testing cost effective (and enhances cascade screening).  Using LDL only, 8-15% false neg and pos, due to overlapping of ranges.  Gene scoring (using SNPs) for mutation neg clinical cases helps to find polygenic cases. But 40% less risk of disease so cascade testing less effective.

American college of med genetics have recommended that familial hypercholesterolaemia (FH) mutations detected on whole genome should be reported to patient.

Cases of sudden cardiac death in 4-6yr olds reported in homozygous.  Heterozygous cases still important – 100X coronary risk age 20-40yrs…

Diagnosis

Diagnosis in childhood could save 50 healthy life years!!!  Dutch cascade screening since 1994 stopped last year. Only 1/3 of known paed cases came clinically, hence big gap in case finding.

Simon Broome criteria – (else use Dutch system) distinguishes Definite FH vs Possible.

  • Definite = DNA pos for known mutation, else tendon xanthomata (personal or 1st or 2nd deg relative) plus cholesterol as below.
  • Possible = cholesterol concentrations as below PLUS:
    • Family history of myocardial infarction: aged younger than 50 years in second-degree relative or aged younger than 60 years in first-degree relative.
    • Family history of raised total cholesterol: greater than 7.5 mmol/l in adult first- or second-degree relative or greater than 6.7 mmol/l in child, brother or sister aged younger than 16 years.

Cholesterol cut offs for Simon Broome

Total cholesterol LDL-C
Child/young person > 6.7 mmol/l > 4.0 mmol/l
Adults > 7.5 mmol/l > 4.9 mmol/l

Refer both definite and possible cases for DNA testing. Plus there are age/sex specific cholesterol cut offs for relative of a known case where DNA is negative.  NICE standard is that children with possible FH should be offered diagnostic tests by age 10.

Given how prevalent use of statins is now, it’s harder to get a positive family history! So history of grandparents more important! 10% have no family history

Only 4% of heterozygotes have xanthomas (can be in buttock cleft, but only look if found elsewhere!). Arcus at 6 oclock in children, all round in adults. Palpable in Achilles tendon rather than seen? Pain in achilles often reported! Resolve with treatment.

Management

NL guidelines – 5-7yr diet etc only.  Diet with plant sterols can drop LDL by 7%

Over 10yrs, treatment (high dose, low dose, combination) depends on mutation and LDL. Most experience with pravastatin.

LDL apheresis as treatment.

Excellent safety and tolerance of statins. Significant reduction within 2 years.

Like any regular medication, compare it to toothbrushing.  Do both at the same time!

Most cardiologists don’t consider FH when high cholesterol found. Nurses? Via labs?

Check growth, puberty, healthy lifestyle. Update family pedigree, contraception.

Smoking confers massive additional risk.  Albert Wiegman has had a 5yr old admitting to smoking…

Treating from age 6.

Outcome

10yr follow up submitted – mean age 24yrs. 7 already older than the age their parent had event. LDL still higher than sibs.

 

Boys have higher risk of cardiac death then girls, but smoking gives girls worse risk than boys.

Intima media thickness – increases year on year, so earlier treatment the better?  Even before age 8 significantly different from non FH.

 

In NICE audit, majority of children not on treatment, and being seen in adult lipid clinics.

No evidence that low fat diets etc are affecting growth (limited numbers so far).

Homozygous FH being recommended as rare disease, so deserving of national specialist service.