Monday, 17 November 2014
Coronary artery disease (CAD)
✔ ️known as atherosclerotic heart disease, atherosclerotic cardiovascular disease, coronary heart disease, ischemic heart disease (IHD), heart attacks.
✔ ️commonly known as a heart attack.
✔ ️An MI occurs when blood stops flowing properly to a part of the heart, and the heart muscle is injured because it is not receiving enough oxygen.
✔ ️Usually this is because one of the coronary arteries that supplies blood to the heart develops a blockage due to an unstable buildup of white blood cells, cholesterol and fat.
✔ ️The event is called "acute" if it is sudden and serious.
ECG Features :
✔ ️ In early STEMIs there may just be peaked T waves with ST elevation developing later.
✔ ️Hyper acute (tall) T waves, ST elevation or new LBBB occur within hours of transmural infarction.
✔ ️ST elevation in two or more adjacent ECG leads.
✔ ️This must be greater than 2 mm (0.2 mV) for males and greater than 1.5 mm (0.15mV) in females if in leads V2 and V3 or greater than 1 mm (0.1 mV) if it is in other ECG leads.
✔ ️ A left bundle branch block that is believed to be new used to be considered the same as ST elevation; however, this is no longer the case.
✔ ️T wave inversion and development of pathological Q waves follow over hours to days
Left ventricular hypertrophy (LVH)
✔ ️the thickening of the myocardium (muscle) of the left ventricle of the heart.
✔ ️LVH itself is not a disease, it is usually a marker for disease involving the heart.
✔ ️Disease processes that can cause LVH include any disease that increases the
afterload that the heart has to contract against, and some primary diseases of the
muscle of the heart.
✔ ️aortic stenosis,
✔ ️aortic insufficiency
✔ ️ hypertension.
✔ ️Primary disease of the muscle of the heart that cause LVH are known as hypertrophic cardiomyopathies, which can lead into heart failure.
✔ ️Long-standing mitral insufficiency.
ECG features :
The Sokolow-Lyon index:
S in V1 + R in V5 or V6 (whichever is larger) ≥ 35 mm (≥ 7 large squares)
R in aVL ≥ 11 mm
The Cornell voltage criteria
for the ECG diagnosis of LVH involve measurement of the sum of the R wave in lead aVL and the S wave in lead V3.
The Cornell criteria for LVH are:
S in V3 + R in aVL > 28 mm (men)
S in V3 + R in aVL > 20 mm (women)
Right ventricular hypertrophy (RVH)
✔ ️Right ventricular hypertrophy (RVH) is a form of ventricular hypertrophy affecting the right ventricle.
✔ ️Blood travels through the right ventricle to the lungs via the pulmonary arteries. If conditions occur which decrease pulmonary circulation, meaning blood does not flow well from the heart to the lungs, extra stress can be placed on the right ventricle. This can lead to right ventricular hypertrophy.
✔ ️Pulmonary hypertension
✔ ️Tetralogy of Fallot
✔ ️Pulmonary valve stenosis
✔ ️Pulmonic regurgitation
✔ ️Ventricular septal defect (VSD)
✔ ️High altitude
✔ ️Cardiac fibrosis
✔ ️Chronic obstructive pulmonary disease (COPD
✔ ️Athletic heart syndrome
ECG features :
✔ ️Right axis deviation (>90 degrees)
✔ ️Tall R-waves in RV leads; deep S-waves in LV leads
✔ ️Slight increase in QRS duration
✔ ️ST-T changes directed opposite to QRS direction (i.e., wide QRS/T angle)
✔ ️May see incomplete RBBB pattern or qR pattern in V1
✔ ️Evidence of right atrial enlargement (RAE)
Specific ECG features (assumes normal calibration of 1 mV = 10 mm):
✔ ️Any one or more of the following (if QRS duration <0.12 sec):
✔ ️Right axis deviation (>90 degrees) in presence of disease capable of causing RVH
✔ ️R in aVR > 5 mm, or
✔ ️R in aVR > Q in aVR
Any one of the following in lead V1:
R/S ratio > 1 and negative T wave qR pattern
R > 6 mm, or S < 2mm, or rSR' with R' >10 mm
Other chest lead criteria:
R in V1 + S in V5 (or V6) 10 mm
R/S ratio in V5 or V6 < 1
R in V5 or V6 < 5 mm
S in V5 or V6 > 7 mm
Sunday, 16 November 2014
✔ ️A first degree Heart block occurs when electrical impulses moving through the
Atrioventricular (AV) node are delayed (but not blocked). First degree indicates
slowed conduction without missed beats.
ECG Features :
✔ ️Look for rhythm that is regular, with heart rate that is the underlying rate.
✔ ️Notice that the P wave is normal.
✔ ️The PR interval is prolonged (>0.20 sec).
✔ ️The QRS is normal (0.06-0.10 sec).
✔ ️PR Interval is Prolonged (>0.20 sec)
✔ ️QRS is Normal (0.06-0.10 sec)
✔ ️A first degree AV block occurs when electrical impulses moving through the
Atrioventricular (AV) node are delayed (but not blocked).
✔ ️First degree indicates slowed conduction without missed beats.
1) Second degree Heart Block Type I Wenckebach
✔ ️ it is a condition where the atrioventricular node conducts each successive impulse
earlier and earlier. The PQ interval prolongs from beat to beat up until a drop-out of
one QRS complex. The following impulse will then be conducted normally and the
cycle to begin again. Thus the presence of second-degree AV block is diagnosed
when one or more (but not all) of the atrial impulses fail to conduct to the ventricles.
ECG Features :
✔ ️Look for rhythm that is irregular but with progressively longer PR interval lengthening,
with heart rate that is the underlying rate.
✔ ️Notice that the P wave is normal.
✔ ️The PR interval is progressively longer until a QRS complex is missed, then cycle
✔ ️The QRS is normal (0.06-0.10 sec).
2) Second degree Heart Block Type II Mobitz
✔ ️it is characterized by intermittently non-conducted P waves which are not preceded by
PR prolongation and are not followed by PR shortening.
✔ ️Mobitz II is usually caused by conduction failure/delay of the His-Purkinje system.
✔ ️In three out of four cases, this conduction block is located distal to the Bundle of His,
creating wide QRS complexes.
✔ ️In the other 25% of cases, the block is located within the Bundle of His, producing
narrower QRS complexes.
ECG Features :
✔ ️Look for rhythm that is regular (atrial) and irregular (ventricular), with heart rate that is
characterised by atrial rate usually faster than ventricular rate (usually slow).
✔ ️Notice that the P wave is normal form, but more p waves than QRS complexes.
✔ ️The PR interval is normal or prolonged.
✔ ️The QRS is normal or wide.
✔ ️None of the SA node impulses reach the ventricles.
✔ ️The ventricles will typically compensate by their own pacemaking, known as an escape
✔ ️Thus the atria and ventricles will beat independently and this can be observed on the
✔ ️The P waves (atrial beating) and QRS complex (ventricles) are unrelated in time.
✔ ️The PR interval will be variable.
ECG Features :
✔ ️Look for rhythm that is regular, but atrial and ventricular rhythms are independent, with
heart rate that is characterised by atrial rate usually normal and faster than ventricular
✔ ️Notice that the P wave is normal shape and size, may appear within QRS complexes.
✔ ️The PR interval is absent: the atria and ventricles beat independently.
✔ ️The QRS is normal, but wide if junctional escape focus.
Friday, 14 November 2014
Cardiac dysarhythmia (also known as arrhythmia or irregular heartbeat) is any of a group of conditions in which the electrical activity of the heart is irregular or is faster or slower than normal.
The heartbeat may be too fast (over 100 beats per minute) or too slow (less than 60 beats per minute), and may be regular or irregular.
|Above is the ECG for "sinus arrhythmia".|
Classification of arrhythmia :
-Premature Atrial Contractions (PACs)
-Wandering Atrial Pacemaker
-Multifocal atrial tachycardia
-Atrial fibrillation (Afib)
2) Junctional arrhythmias
-Supraventricular tachycardia (SVT)
-AV nodal reentrant tachycardia is the most common cause of -
Paroxysmal Supra-ventricular Tachycardia (PSVT)
-Premature junctional contraction
-Premature ventricular contractions (PVCs), sometimes called
ventricular extra beats (VEBs)
-Premature ventricular beats occurring after every normal beat are
termed "ventricular bigeminy"
-PVCs that occur at intervals of 2 normal beats to 1 PVC are
termed "PVCs in trigeminy"
-Accelerated idioventricular rhythm
-Monomorphic Ventricular tachycardia
-Polymorphic ventricular tachycardia
4) Heart blocks
i. First degree heart block, which manifests as PR prolongation
ii. Second degree heart block
-Type 1 Second degree heart block, also known as Mobitz I or Wenckebach
-Type 2 Second degree heart block, also known as Mobitz II
iii. Third degree heart block, also known as complete heart block.
Abnormalities of normal sinus, it can be :
i. "sinus tachycardia"
✔ ️ Rate >100.
✔ ️ Causes: Anaemia, anxiety, exercise, pain, high T°, sepsis, hypovolaemia, heart failure, pulmonary embolism, pregnancy, thyrotoxicosis, beri beri, CO2 retention, autonomic neuropathy, sympathomimetics.
ii. "sinus bradycardia"
✔ ️ Rate <60.
✔ ️ Causes: Physical fitness, vasovagal attacks, sick sinus syndrome, acute MI (esp. inferior), drugs
(beta- blockers, digoxin, amiodarone, verapam- il), hypothyroidism, hypothermia, high intracranial pressure, cholestasis.
But in "sinus arrhythmia",
✔ ️ it is disturbances of cardiac rhythm or arrhythmias are:
• Often benign (but may reflect underlying heart disease)
• Often intermittent, causing diagnostic difficulty
• Occasionally severe, causing cardiac compromise.
✔ ️ causes are :
1) Cardiac: MI, coronary artery disease, LV aneurysm, mitral valve disease, cardiomyopathy, pericarditis, myocarditis, aberrant conduction pathways.
2) Non- cardiac: Caffeine, smoking, alcohol, pneumonia, drugs (Bete2-agonists, digoxin, L-dopa, tricyclics, doxorubicin), metabolic imbalance (K+, Ca2+,Mg2+, hypoxia, hypercapnia, metabolic acidosis, thyroid disease), and phaeochromocytoma.
Saturday, 8 November 2014
The electrocardiogram (ECG or EKG) is a diagnostic tool that is routinely used to assess the
electrical and muscular functions of the heart. The electrocardiogram can measure the rate
and rhythm of the heartbeat, as well as provide indirect evidence of blood flow to the heart
The electrocardiogram translates the heart's electrical activity into line tracings on paper.
The spikes and dips in the line tracings are called waves.
• The P wave is a record of the electrical activity through the upper heart chambers
• The QRS complex is a record of the movement of electrical impulses through the
lower heart chambers (ventricles).
• The ST segment shows when the ventricle is contracting but no electricity is flowing
through it. The ST segment usually appears as a straight, level line between the QRS
complex and the T wave.
• The T wave shows when the lower heart chambers are resetting electrically and
preparing for their next muscle contraction.
Heart Function and the ECG
Electrode leads on the chest wall are able to detect electrical impulses that are generated by
the heart.. By interpreting the tracing, the physician can learn about the heart rate and
rhythm as well as blood flow to the ventricles (indirectly).
Picture of rhythm strip showing a normal 12-lead ECG
Rate refers to how fast the heart beats. Normally, the SA node generates an electrical
impulse 60-100 times per minute. Bradycardia (brady=slow+cardia=heart) describes a heart
rate less than 60 beats per minute. Tachycardia (tachy=fast+cardia=heart) describes a heart
rate faster than 100 beats per minute.
Rhythm refers to the type of heartbeat. Normally, the heart beats in a sinus rhythm with
each electrical impulse generated by the SA node resulting in a ventricular contraction, or
There are 8 steps method to interprete a rhythm strip:
• Step 1: Determine the rhythm
-For atrial rhythm, measure the P-P intervals
-To determine the ventricular rhythm measure the intervals between two consecutive R
waves in the QRS complexes.
• Step 2: Determine the rate
• Step 3: Evaluate the P wave
• Step 4: Measure the PR interval
• Step 5: Determine the QRS complex duration
• Step 6: Examine the T waves
• Step 7: Measure the QT interval duration
• Step 8: Check for ectopic beats and other abnormalities
What makes sinus rhythm normal?
1. Atrial and ventricular rhythms are regular.
2. Atrial and ventricular rates fall between 60 and 100 beats/minute, the SA node’s
normal firing rate, and all impulses are conducted to the ventricles.
3. P waves are rounded, smooth, and upright in lead II, signaling that a sinus impulse has
reached the atria.
4. The PR interval is normal (0.12 to 0.20 second), indicating that the impulse is
following normal conduction pathways.
5. The QRS complex is of normal duration (less than 0.12 second), representing normal
ventricular impulse conduction and recovery.
6. The T wave is upright in lead II, confirming that normal repolarization has taken place.
7. The QT interval is within normal limits (0.36 to 0.44 second).
8. No ectopic or aberrant beats occur.
There are a variety of abnormal electrical rhythms, some are normal variants and some are
potentially dangerous. Some electrical rhythms do not generate a heartbeat and are the
cause of sudden death.
Examples of heart rhythms include:
• Normal sinus rhythm
• Sinus tachycardia
• Sinus bradycardia
• Atrial fibrillation
• Atrial flutter
• Ventricular tachycardia
• Ventricular fibrillation
There can also be delays in transmission of the electrical impulse anywhere in the system,
including the SA node, the atria, the AV node, or in the ventricles. Some aberrant impulses
cause normal variants of the heart rhythm and others can be potentially life threatening.
Some examples include:
• 1st degree AV block
• 2nd degree AV block, type I (Wenckebach)
• 2nd degree AV block, type II
• 3rd degree AV block or complete heart block
• Right bundle branch block
• Left bundle branch block
There can also be short circuits that can lead to abnormal electrical pathways in the heart
causing abnormalities of rate and rhythm. Wolfe-Parkinson-White (WPW) syndrome is a
condition where an abnormal accessory pathway at the AV node causes tachycardia.
The ECG tracing can also provide information about whether the heart muscle cells are
conducting electricity appropriately. By analyzing the shape of the electrical waves, the
physician may be able to determine if there is decreased blood flow to parts of the heart
muscle. The presence of an acute blockage associated with a myocardial infarction or heart
attack can be determined as well. That's one of the reasons that an ECG is done as soon as
possible when a patient presents with chest pain.
Reasons to Have an ECG
The ECG is used to assess heart function. Patients who complain of chest pain or shortness of
breath will often have an ECG as one of the first tests to help determine if there is an acute
myocardial infarction or heart attack present. Even if there is no heart attack, the ECG can
help decide whether the pain is due to angina or narrowing of blood vessels to the heart
muscle (atherosclerosis). It is important to realize that an initial ECG may be normal even if
there is heart disease present. Serial EKGs may be needed over time to find an abnormality.
ECGs are often performed when a patient complains of lightheadedness, palpitations, or
syncope (passing out) since abnormal heart rate and rhythms may affect the heart's ability to
pump blood and provide the body with oxygen.