ECG CHANGES IN HOCM

Dr.suryakala2nd year pg

General medicine

ECG Manifestations in HCM

• Ventricular hypertrophy• Intraventricular conduction defects : Left

anterior hemiblock and bundle branch block• Left and/or right atrial abnormality• ECG resembling WPW syndrome• Prolongation of QT interval• Disturbances of cardiac rhytm

Ventricular hypertrophy

May affect one or more of the following regions:• The interventricular septum• The left free wall• Apical and Paraseptal regions• Right ventricle

SEPTAL HYPERTROPHY• Deep and norrow q waves in leads V2-6,II and III and aVF• Frontal plane q wave axis is directed to -1300

• Prominent initial r wave in lead V1.This, together with findings listed under Indicate an initial 0.04s QRS vector which is directed superiorly, to

the right and slightly anteriorly Left axis deviation, mean frontal QRS axis is directed to about –450

S wave in lead V1 is not increased in magnitude The R wave in left precordial leads is of low amplitude Tendencty to low QRS amplitude throughout.

The manifestation of abnormal q waves in the absence of any evidence of left free-wall hypertrophy indicates dominant septal hypertrophy

Left Ventricular hypertrophy• Deep S waves in leads V1-3• Tall R waves in leads V5-6• Sum of S wave in leads V1 and tall R waves in leads V6 is equal to

70mm(Normal <35mm)• Depth of S wave in lead V1 is 30mm(Normal <20mm)• Total QRS is >301mm(Normal <175mm)• Amplitude of R wave in V6 is greater than V5(Reverse is normal)• Systolic overload is reflected by inverted T waves in the left oriented

leads.HCM is Suggested by Association of right atrial abnormality and left ventricular hypertrophy Ths short PR interval Shelf like nagulation of the ST segments in standard lead I,V5 and V6

APICAL HCM

• P waves are normal• Frontal QRS axis is directed to +70• Tall R waves in V4-6• Epicardial injury is reflected by elevated ST segments in

lead II and leads aVF, and V2-6• ST segments have an initial horizontality , forming a

characteristic initial ‘shelf’, with a well marked ST-T angle in leads V3-6

• Myocardial ischemia reflected by symmetrical, sharply, pointed inverted T waves in leads V3-6

RIGHT VENTRICULAR HCM

• Right axis deviation – Mean frontal plan QRS axis is usually in the right inferior quadrant, and may even be found in the region of +/-1800

• Right ventricular systolic overload – reflected by tall R waves and inverted T waves in the right precordial leads

• Right atrial enlargement – tall and peaked P waves particularly lead II

• Complete or incomplete right bundle branch block

INTRA VENTRICULAR CONDUCTUION DEFECTS

Left anterior hemiblock – • In about one third cases frontal QRS axis is deviated to

the left usually to -300

• Even more significant sign of HCM , if manifests in childLeft bundle branch block – Incomplete heart bundle branch block is frequent

association, earliest manifestation is the disappearance of the small normal initial q wave in the left oriented leads.

Atrial abnormality

• Reflect manifestations of left/right atrial abnormality

• Biatrial abnormality manifest with tall, wide and notched P waves, particularly lead II

• An uncommon combination of right atrial abnormality with left ventricular hypertrophy or strain is very suggestive of HCM

Disorders of cardiac rhythm

• HCM is associated with increased incidence of cardiac arrhytmias, even in asymptomatic individuals

• Include Ventricular premature complexes, paroxysmal ventricular tachycardia, which may cause sudden cardiac death

• Less commonly, supreventricular tachycardia and atrial fibrillation

EVOLUTION OF ECG CHANGES IN HCM

Common changes in order of frequency Left ventricular hypertrophy Left atrial abnormality Pathological q waves Prolongation of corrected QT interval Right ventricular hypertrophy

Regression of ECG features with disappearance of pathological q waves or disappearance of left ventricular hypertrophy In absence of newly developed pathological q waves in minority.

Evolution of ECG changes tends to occur more commonly in patients with left ventricular obstruction at diagnosis, younger age at diagnosis and with longer follow up periods

ROLE OF ECG IN SCREENING OF HCM

• Invaluable tool in mass screening of population where echocardiography is not cost effective.

• Ecg manifestations may be the initial manifestation of hemolytic crisis, appearing even before LV hypertrophy is detectable by echocardiogram.

• ECG is more sensitive than ECHO during family screening for identifying non-hypertrophic carriers of certain mutations especially TnT, TnI, MBPC

• Pathological Q waves and repolarisation abnormalities are highly specific, and are often present in children with sarcomere protein gene mutations before the development of echocardiographic LV hypertrophy.