part III

Simplified ECG part III : 

Simplified ECG part III Sayed Syleem, MSc Cardiologist Kafr Saad central hospital 2010

و في الأرضِ آياتٌ للموقنينَ * و في أنفُسِكم أفلا تُبْصِرونَ * : 

و في الأرضِ آياتٌ للموقنينَ * و في أنفُسِكم أفلا تُبْصِرونَ * الذاريات 20 و 21

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N ormal sinus rhythm E ach P wave is followed by a QRS P wave rate 60 - 90 bpm with <10% variation rate <60 = sinus bradycardia rate >100 = sinus tachycardia variation >10% = sinus arrhythmia

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Normal P waves H eight < 2.5 mm in lead II W idth < 0.11 s in lead II for abnormal P waves ( RAE , LAE , PACs , hyperkalaemia )

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N ormal PR interval 0.12 - 0.20 s (3 - 5 small squares) for short PR segment consider WPW syndrome or LGL syndrome (other causes - Duchenne muscular dystrophy, type II glycogen storage disease, HOCM ) for long PR interval consider first degree HB and trifasicular ' block

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N ormal QRS complex < 0.12 s duration (3 small squares ) for abnormally wide QRS consider BBB , ventricular rhythm, WPW, hyperkalaemia … N o pathological Q waves N o evidence of LVH or RVH

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N ormal QT interval Calculate the corrected QT interval ( QTc ) by dividing the QT interval by the square root of the preceeding R - R interval. Normally= 0.42 - 0.44 s. Causes of long QT interval MI, myocarditis , diffuse myocardial disease H ypocalcaemia , hypothyrodism S ubarachnoid haemorrhage , I ntracerebral haemorrhage D rugs (e.g. sotalol , amiodarone ) H ereditary Romano Ward syndrome Jervill -Lange -Nielson syndrome

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N ormal ST segment N o elevation or depression C auses of elevation include acute MI ( anterior , inferior ), LBBB , normal variants (athletic heart), acute pericarditis C auses of depression include myocardial ischaemia , digoxin effect , ventricular hypertrophy , acute posterior MI , pulmonary embolus , LBBB

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N ormal T wave C auses of tall T waves include: hyperkalaemia , hyperacute MI and LBBB C auses of small, flattened or inverted T waves are numerous and include: ischaemia , age, race, hyperventilation, anxiety, drinking iced water, LVH , drugs ( digoxin ), pericarditis , PE , intraventricular conduction delay ( RBBB ) and electrolyte disturbance.

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Bazett's Formula : QT c = (QT)/ SqRoot RR (in seconds) Poor Man's Guide to upper limits of QT: For HR = 70 bpm , QT < 0.40 sec; for every 10 bpm increase above 70 subtract 0.02 sec, a for every 10 bpm decrease below 70 add 0.02 sec. QTc

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Normal q-waves reflect normal septal activation (beginning on the LV septum); they are narrow (<0.04s duration) and small (<25% the amplitude of the R wave). They are often seen in leads I and aVL when the QRS axis is to the left of +60 o , and in leads II , III , aVF when the QRS axis is to the right of +60 o . Q-wave

Right Atrial Enlargement : 

Right Atrial Enlargement The P wave in leads II, II and aVF is peaked with a height greater than 2.5mm. "P pulmonale " The P wave axis is +75 or greater. The positive aspect of the P wave in lead V1 or V2 is >1.5mm in height.

Left atrial enlargement : 

Left atrial enlargement Negative phase of PV1>0.04 sec — sensitivity 83 percent; specificity 80 percent Negative phase of PV1>1 mm — sensitivity 60 percent; specificity 93 percent P-terminal force >0.04 mm/sec — sensitivity 69 percent; specificity 93 percent Notched P, interpeak interval >0.04 sec — sensitivity 15 percent; specificity 100 percent P wave duration >0.11 sec — sensitivity 33 percent; specificity 88 percent P wave/PR duration >1.6 — sensitivity 31 percent; specificity 64 percent

Biatrial Enlargement: 

Biatrial Enlargement A large biphasic P wave in lead V1 with the initial component greater than 1.5mm in height and  the terminal component at least 1mm in depth and 0.04 sec in duration. A P wave amplitude of >2.5mm and duration of >0.12 seconds in the limb leads. II.

Right Ventricular Hypertrophy: 

Right Ventricular Hypertrophy Right axis deviation of +110 or more R/S ratio > 1 in lead V1 R wave lead V1 < 7mm S wave lead V1 < 2mm qR in V1 rSR ' V1 with R' >10mm

Left Ventricular Hypertrophy: 

Left Ventricular Hypertrophy Limb Leads (Low sensitivity, high specificity) R wave lead I + S wave lead III > 25 mm R wave aVL > 11mm R wave aVF > 20mm S wave in aVR > 14mm Precordial Leads (High sensitivity, low specificity) R wave V5 or V6 > 26mm R wave V5 or V6 + S wave in V1 > 35mm Largest R wave + largest S wave in precordial leads > 45mm

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Other criteria Sokolow + Lyon (Am Heart J, 1949;37:161) S V1+ R V5 or V6 > 35 mm Cornell criteria (Circulation, 1987;3: 565-72) SV3 + R avl > 28 mm in men SV3 + R avl > 20 mm in women Framingham criteria (Circulation,1990; 81:815-820) R avl > 11mm, R V4-6 > 25mm S V1-3 > 25 mm, S V1 or V2 + R V5 or V6 > 35 mm, R I + S III > 25 mm Romhilt + Estes (Am Heart J, 1986:75:752-58) Point score system

Biventricular Hypertrophy: 

Biventricular Hypertrophy One or more criteria for both left and right ventricular hypertrophy LVH in the precordial leads with an axis > +90 o

Left Ventricular Strain: 

Left Ventricular Strain Left ventricular hypertrophy is often associated with ST depression and deep T wave inversion. These changes occur in the left precordial leads, V5 and V6.

Right Ventricular Strain: 

Right Ventricular Strain Right ventricular hypertrophy can be associated with ST depression and T wave inversion in the right precordial leads, V1 - V3.

Low Voltage: 

Low Voltage Voltage of entire QRS complex in all limb leads < 5mm. Voltage of entire QRS complex in all precordial leads < 10mm.

The END next..( Part IV): 

The END next..( Part IV)