28/10/2009 1

ECG OF THE WEEK

M7 UNIT

Prof. Dr. P. Vijayaraghavan’s unit

By Dr. J. Stalin Roy

28/10/2009 2

Background

• 17 yr old female presented with history of consumption of detergent bleach ‘ala’ (around 50ml)

• Her only complaint was retrosternal and epigastric burning sensation.

• Routine evaluation was done.• Her ECG is shown in the following slide.

28/10/2009 3

•Normal sinus rhythm

•Rate 85,

•Normal P wave,

•PR interval

•Normal QRS axis, morphology,

•ST, T normal,

•QTc = 400/(0.70)½ = 478ms

320ms (0.32sec)

ECG taken on the 1st day

28/10/2009 4

•PR interval has normalized to

140 ms (0.14 sec)

ECG taken on the 3rd day

28/10/2009 5

• This is a rare case presenting with first degree AV block after consuming ‘ALA’ bleach, the main component of which is sodium hypochlorite & amine oxide.

• The block subsided after two days spontaneously probably after complete elimination of the toxin from the body

• There are no previous reports in medical literature implicating hypochlorite in AV blocks.

28/10/2009 6

Sodium hypochlorite poisoning

• Ingestion of small volumes of sodium hypochlorite causes burns to the mouth and throat, gastrointestinal irritation, nausea and vomiting.

• Aspiration of liquid may lead to pulmonary complications such ARDS.

• Exposure to higher concentrations may lead to tachypnoea, cyanosis, swelling of the airway, and in severe cases, pulmonary oedema and respiratory failure

• Sodium hypochlorite is corrosive and may cause skin blisters.

• Ocular exposure can cause irritation, pain, lacrimation and photophobia.

28/10/2009 7

First-degree AV block

• First-degree atrioventricular (AV) block is defined as a PR interval exceeding 0.20 seconds.

28/10/2009 8

Causes

• Athletic training• Acute MI• Idiopathic degenerative diseases of the

conduction system• Lev disease• Lenègre disease

• Drugs: • Calcium channel blockers, • Beta-blockers, • Digoxin, • Amiodarone

28/10/2009 9

• Mitral or aortic valve annulus calcification • Infectious disease:

• Infective endocarditis, • Diphtheria, • Rheumatic fever, • Chagas disease,• Lyme disease, • Tuberculosis

28/10/2009 10

• Collagen vascular disease: • Rheumatoid arthritis• systemic lupus erythematous• scleroderma

• Fetuses of pregnant women who are anti-SSA/Ro positive.

• Infiltrative diseases such as amyloidosis or sarcoidosis

• Myotonic dystrophy• Iatrogenic

28/10/2009 11

• Signs • Asymptomatic at rest. • Markedly prolonged PR interval may reduce

exercise tolerance in patients with left ventricular systolic dysfunction.

• Syncope may result from transient high-degree AV block and in those with infranodal block and wide QRS complex.

• Symptoms • The intensity of the first heart sound (S1) is

decreased in patients with first-degree AV block.

• Patients with first-degree AV block may have a short, soft, blowing, diastolic murmur heard at the cardiac apex. The diastolic murmur is thought to be related to antegrade flow through closing mitral valve leaflets that are stiffer than normal.

28/10/2009 12

Workup • Imaging:

• In patients with first-degree AV block and left ventricular systolic dysfunction, Doppler ultrasound may be used to document an improvement in cardiac output during dual-chamber pacing.

• This may provide evidence for the appropriateness of implanting a permanent pacemaker.

• His bundle ECG: • This is necessary only in patients with

symptomatic first-degree AV block and a wide QRS complex.

• Is used to locate the site of the block in these patients.

• As many as 50% of patients show an infranodal conduction delay.

28/10/2009 13

Treatment

• Patients with asymptomatic first-degree AV block need no treatment

• In patients with symptomatic first-degree AV block medications with potential for AV block must be discontinued if possible.• Permanent electronic pacemakers may be

indicated in those with the following:• Severe bradycardia• Syncope associated with infranodal block• Left ventricular systolic dysfunction, when a

shorter AV delay has been shown to improve hemodynamic condition

• Medications

28/10/2009 14

• Complications• Progression to higher degrees of AV block

• Reduction in left ventricular stroke volume and

cardiac output

• Pseudo-pacemaker syndrome

• Prognosis• Isolated first-degree AV block carries no

increased risk of mortality.

• Patients with first-degree AV block and

infranodal blocks have increased risk of

progression to complete AV block.

28/10/2009 15

Pseudo pacemaker syndrome

• AV dyssynchrony syndrome • Found in

• Extremely prolonged first-degree AV block• Nodal rhythm more rapid than the atrial rate, as

might occur in children with sinus node dysfunction after congenital defect repair

• Hypertrophic cardiomyopathy with complete AV block

• Due to loss of physiologic timing of atrial and ventricular contractions resulting in loss of ‘atrial kick’

• Treatment :• Treat the AV block• Some improvement with Atropine

28/10/2009 16