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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_2818_Библиотеки_им_академика_М_И_Перельмана
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320
Accessory
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24 ECG inMiscellaneous Heart Diseases
24.4 Miscellaneous Conditions
24.4.1 Preexcitation Syndrome (WPW Syndrome)
Wolff–Parkinson–White syndrome (WPW) is the prototype of preexcitation syndrome. This electrocardiographic syndrome is mainly due to an anomalous atrioventricular pathway or the accessory pathway (Fig. 24.10). This pathway is of
congenital origin and bypasses the AV node. This accessory pathway is known as
Bundle of Kent. WPW syndrome is commonly associated with Ebstein’s anomaly
and hypertrophic cardiomyopathy.
The ECG of WPW syndrome has the following features:
• Short P-R interval (< 0.12s)
• Widened QRS complex (> 0.12s)
• Delta wave: This is the slurred upstroke of QRS complex (Figs.24.11 and 24.12)
• Secondary S-T segment, T wave change
Depending upon the location of the accessory pathway in relation to the SA node
and the relative transmission characteristics of the accessory pathway and the AV
node, the morphology of the ECG may vary from a classic presentation to
near normal.
The treatment of preexcitation is mainly removal of the accessory pathway. The
pathway is detected precisely by electrophysiological studies and then it is removed
by radio frequency catheter ablation (Fig.24.13).
Fig. 24.10 The accessory
pathway
pathway
25 mm/s. 10 mm = 1 mV
24.4 Miscellaneous Conditions
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Fig. 24.11 WPW
syndrome. Note the delta
wave, short P-R interval,
wide QRS complex and the
accompanying S-T
segment, T wave change
Delta wave
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Wide QRS complex
I
aVR
V1
II
aVL
V2
Short P-R interval
III
aVF
V3
S-T
, T change
V4
Fig. 24.12 WPW syndrome. This ECG is taken from a 40-year-old gentleman who presented with
PSVT.After termination of PSVT, the ECG revealed WPW syndrome. Note the wide QRS complexes with delta waves and short P-R interval
V5
V6
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SA
A
cathete
Radio frequency
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24 ECG inMiscellaneous Heart Diseases
node
blation
r
AV node
Fig. 24.13 Radiofrequency catheter ablation of bypass tract
discharge
24.4.2 Myocarditis
Myocarditis is acute infection of the myocardium. Almost any acute infectious disease may involve the myocardium. Myocarditis may be due to viral or bacterial
origin. It is very frequently a part of rheumatic fever. The ECG features are:
• S-T segment, T wave changes in chest leads
• First-degree heart block or defective intraventricular conduction
• Prolongation of Q-Tc interval
• Various types of arrhythmias
• QRS abnormalities that may mimic myocardial infarction
24.4.3 Cardiac Trauma
ECG changes may be seen in both penetrating and non-penetrating cardiac trauma.
The ECG abnormalities may be the following:
• Various types of arrhythmias
• Non-specic S-T segment, T wave changes
• Features similar to pericarditis
• Changes of myocardial infarction
25 mm/s. 10 mm = 1 mV
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323
24.4.4 Cardiac Malignancy
Primary cardiac malignancy is rare but metastasis to heart is not uncommon. Cardiac
malignancy is often not diagnosed in life. The ECG features of cardiac malignancy
are the following:
• Atrial or ventricular arrhythmias
• Features similar to pericarditis
• Features similar to myocardial infarction
24.4.5 Hypertrophic Cardiomyopathy
Hypertrophic cardiomyopathy (HOCM) is characterized by asymmetric hypertrophy of the left ventricle. The interventricular septum is markedly hypertrophied.
The ECG features are the following:
• Features of LVH and rarely of RVH.Due to septal hypertrophy, there are deep
and narrow Q waves in left and inferior oriented leads (Fig.24.14).
• Intraventricular conduction defects in the form of bundle branch block or LAHB.
• Enlargement of left and/or right atrium.
• Prolongation of P-R and Q-Tc interval.
• Cardiac arrhythmias.
I
V1
Fig. 24.14 HOCM.The ECG shows evidence of LVH in precordial as well as limb leads. There
are deep dagger shaped narrow Q waves in leads II, III, aVF and leads V5 and lead V6
V2
II
III
V3
aVR
V4
aVL
V5
aVF
V6
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24 ECG inMiscellaneous Heart Diseases
24.4.6 Parasystole
Parasystole is a type of dual rhythm where two pacemakers together but independent of each other govern the rhythm of the heart. In normal condition, the sinus
pacemaker that is the SA node controls the heart rhythm. The sinus pacemaker
prematurely discharges all the other slower and subsidiary pacemakers. Thus, it can
be said that the sinus pacemaker dominates over the other potential pacemakers.
However, in some cases the subsidiary pacemakers develop the property to protect
themselves from the effect of the sinus or other dominant pacemaker and they are
not affected by the dominant pacemaker. In those conditions, the two pacemakers
together but independent of each other govern the rhythm of the heart and this is
known as parasystole. The commonest parasystole is ventricular parasystole. The
ECG features are:
• Varying coupling interval. It is the interval between the ventricular ectopic beat
and the preceding sinus beat. In simple ventricular extrasystoles, the coupling
intervals are constant, but in parasystole they vary.
• The intervals between ectopic beats are in multiples of shortest interectopic
interval.
• Fusion beats.
24.4.7 Dextrocardia
Dextrocardia is congenital malposition of heart. The left ventricle and left atrium
are present in the right side of right ventricle and right atrium. The right atrium is on
the left side and the aortic knob is on the right side. The ECG features of dextrocardia are the following:
• Inverted P waves in leads I and aVL.
• QRS complexes are upright in leads II, III and aVF.
• QRS complexes are negative in leads I and aVL.
• The P, QRS and T waves in aVL resemble that of aVR and vice versa (Fig.24.15).
• R wave is prominent in lead V1 and the height of R wave gradually diminishes
in lead V6, because the lead V1 overlies left ventricle and lead V6 overlies right
ventricle.
• The P, QRS and T waves in leads V4R and V5R resemble that of leads V4 and V5.
• The QRS axis is the mirror image of the normal QRS axis (+60°), i.e. +120°.
V4R
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I III
V1 V2
25 mm/s. 10 mm = 1 mV
V3R
Fig. 24.15 Dextrocardia. Note the negative complexes in lead aVL and positive complexes in
lead aVR
II
V3
V5R V6R
aVR
V4
aVL aVF
V5 V6
24.4.8 Dextroversion
Dextroversion is congenital malposition of heart. The heart is displaced to right and
the ventricles are rotated in counterclockwise direction. The ventricles and the atria
are not transposed. The aorta is in normal position. QRS vector is directed more
anteriorly because of counterclockwise rotation of heart. The T wave is inverted in
lead I (Fig.24.16).
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V5 V6
V1 V2
V3
V4
V1 V2
V3
V4
V5 V6
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24 ECG inMiscellaneous Heart Diseases
I III
25 mm/s. 10 mm = 1 mV
Fig. 24.16 Dextroversion
I III
II
II
25 mm/s. 10 mm = 1 mV
aVR
aVR
aVL aVF
aVL aVF
Fig. 24.17 Technical dextrocardia
24.4.9 Technical Dextrocardia
Technical dextrocardia is the term used when ECG is recorded by mistake in which
the right and the left arm electrodes are interchanged with each other. There are
features of dextrocardia in limb leads (Fig.24.17). The recordings in chest leads
are normal.
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24.4.10 Brugada Syndrome
Brugada syndrome is an inherited, rare, life threatening disease that predisposes to
fatal cardiac arrhythmias. It is more common in males than females. It is often
responsible for sudden cardiac death. The main ECG features are:
• Right bundle branch block
• S-T segment elevation in leads V1–V3
Three different ECG patterns have been described in Brugada syndrome patients:
• Type 1: Coved S-T segment elevations greater than 2mm accompanied with an
inverted T wave (Fig.24.18)
• Type 2: Saddleback-shaped S-T segment elevation greater than 2mm
• Type 3: Saddle-back shaped S-T segment elevations less than 2mm
I
V1
25 mm/s. 10 mm = 1 mV
Fig. 24.18 Brugada syndrome. Coved S-T segment elevation >2mm in leads V1–V3 followed by
a negative T wave
II
V2 V3
III
aVR
V4
aVL aVF
V5
V6
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24 ECG inMiscellaneous Heart Diseases
Tips and Tricks
• If you nd P mitrale, suspect mitral stenosis.
• If you nd concave upwards S-T segment elevation, think of acute pericarditis.
• If you nd electric alternans, think of pericardial effusion.
• If you nd rSR’ complex in lead V1 with right axis deviation, think of ostium
secundum ASD.
• If you detect short P-R interval, think of WPW syndrome. Next you should look
for presence of delta wave.
• If you nd QRS complex negative in aVL and positive in lead aVF, think of
dextrocardia.
• If you nd coved S-T segment elevation in leads V1–V3 with T wave inversion,
think of the possibility of Brugada syndrome.
Self-Assessment Questions
1. Mitral stenosis is typically associated with a wide and notched P wave on the
ECG.True or false?
2. Pericardial effusion can lead to low voltage QRS complexes on the ECG.True
or false?
3. Rheumatic heart disease can cause a prolonged P-R interval and sinus tachycar-
dia on the ECG.True or false?
4. P-R interval is more than 0.2s in WPW syndrome. True or false?
5. Features of RVH in ECG are seen in Fallot’s tetralogy. True or false?
6. Dextrocardia is most commonly associated with:
a. Atrial brillation b. Negative complexes in lead aVL c. Sinus bradycar-
dia d. Complete heart block
7. WPW syndrome is characterized by:
a. Prolonged P-R interval b. Delta waves c. Tall R waves in V1 d.
Absent P waves
8. ECG ndings in ostium secundum ASD may include:
a. Right axis deviation b. Left bundle branch block c. Peaked T waves in
precordial leads d. Deep S waves in lead V1
9. VSD can lead to which ECG abnormality?
a. Left ventricular hypertrophy b. Prolonged P-R interval c. Tall R waves in
V1 d. Upsloping S-T segment depression
10. In pericarditis ECG shows:
a. S-T segment elevation with concavity upwards b. S-T segment is isoelec-
tric c. S-T segment elevation with convexity upwards d. Tall T waves
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Case Studies
1. A 35-year-old gentleman presented with history of fever for vedays followed
by retrosternal, sharp chest pain which increases on lying down. The pain
improves upon sitting up and bending forward. On auscultation, a supercial
scratchy sound is audible over the precordium. Pulse rate was 110bpm and
blood pressure was 110/70mmHg and temperature was 100.2°F.His ECG is
given in Fig.24.19. What is your diagnosis?
2. A 6-year-old male child suffering from cough and cold for twodays was exam-
ined by a paediatrician. A soft ejection systolic murmur was audible over the
pulmonary area and a wide xed splitting of second heart sound was detected.
His ECG is given in Fig.24.20. What is your diagnosis?
3. A 30-year-old gentleman presented with history of three episodes of palpitation
over last oneyear. Each episode lasted for about two minutes and stopped of its
own. He has no history of hypertension, diabetes or dyslipidaemia. Physical
examination was unremarkable. His ECG is given in Fig.24.21. What is your
diagnosis?
4. A 45-year-old gentleman suffering from pulmonary tuberculosis presented with
history of fatigue, swelling of feet, chest pain and breathlessness that improves
on sitting up. Examination revealed mufed heart sound, blood pressure of
96/70mmHg and pulse rate 114bpm, temperature 99°F.Chest X-ray showed
nonhomogeneous opacities in left apex and water bottle shaped cardiac shadow.
His rhythm strip is given in Fig.24.22. Identify the rhythm and name the condition in which you will get it.
I
V1 V2
25 mm/s. 10 mm = 1 mV
Fig. 24.19 Interpret the ECG
II
III
V3
aVR
V4
aVL
V5
aVF
V6
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