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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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https://t.me/med1917
22 ECG inElectrolyte Imbalance
2. A 60-year-old lady presented with history of numbness and tingling in perioral
area, ngers and toes for last vedays. She also complained of backache. On
examination, she did not seem to be in any apparent distress. Her blood pressure
was 110/84mmHg, pulse rate was 72bpm, afebrile, heart sounds were normal
and chest was clear. Her rhythm strip is given in Fig. 22.15. Identify the
abnormality.
3. A 26-year-old lady presented with history of several bouts of watery diarrhoea
and vomiting for past twenty four hours. On examination, her blood pressure was
100/60mmHg, pulse rate was 100bpm. Her rhythm strip is given in Fig.22.16.
Identify the abnormality.
4. A 57-year-old gentleman suffering from renal cell carcinoma presented with his-
tory of episodic abdominal pain, nausea and vomiting for last 3months, back-
ache and left knee pain, increased thirst, fatigue and lethargy. His rhythm strip is
given in Fig.22.17. What does the ECG show?
5. The rhythm strip in Fig.22.18 is given for spot diagnosis in nal year MBBS
examination. What is your diagnosis?
Lead II 25 mm/s. 10 mm = 1 mV
Fig. 22.15 Identify the ECG abnormality
Lead II 25 mm/s. 10 mm = 1 mV
Fig. 22.16 Identify the ECG abnormality
Lead II 25 mm/s. 10 mm = 1 mV
Fig. 22.17 Analyse the rhythm strip
Lead II 25 mm/s. 10 mm = 1 mV
22.3 Magnesium Effect
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Fig. 22.18 Analyse the rhythm strip
301
Answers
1. True 2. True 3. True 4. True 5. False 6. d 7. a 8. b 9. c 10. a
Case Studies
1. The ECG (Fig.22.14) shows hyperkalaemia. There are tall and tented T waves
in leads V4, V5 and V6. There is also widening of QRS complexes. If untreated,
the P waves will disappear; there will be further widening of QRS complex and
there may be sine wave appearance. Ventricular brillation and asystole
may follow.
This patient should be urgently given intravenous calcium to negate the cardiac toxicity. Glucose plus insulin intravenous drip should be started without
delay to increase intracellular uptake of potassium, thereby reducing serum
potassium. Cation exchange resin like sodium polystyrene sulfonate should be
started later on. The combination of ACE inhibitor and ARB may cause hyperkalaemia, especially in presence of kidney dysfunction. Hence, kidney function
should be assessed and this combination of antihypertensives should be stopped
at the earliest.
2. The rhythm strip (Fig.22.15) shows hypocalcaemia. There is Q-T interval prolongation. It is 0.52s.
Hypocalcaemia is commonly due to inadequate levels of vitamin D or parathyroid hormone or resistance to these hormones. Treatment is with oral calcium
and vitamin D supplements. It is important to correct coexisting magnesium
deciency if any.
In acute hypocalcaemia, intravenous calcium gluconate is given.
3. The ECG (Fig.22.16) shows hypokalaemia. There is U wave which is bigger in
amplitude as compared to the T wave. This signies that these are not the normal
U waves which are often seen in healthy people. The patient is suffering from
acute gastroenteritis. There is loss of potassium in watery loose stool and
vomiting.
The patient should be started intravenous potassium infusion at a rate of
10–20mEq every hour. If potassium level does not correct, look out for coexisting hypomagnesaemia. Treat acute gastroenteritis with IV uids and antiemetics.
Appropriate antibiotics may be started as early as possible if required.
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22 ECG inElectrolyte Imbalance
4. The ECG (Fig.22.17) shows hypercalcaemia. The Q-T interval is shortened. It
is 0.28s.
Hypercalcaemia in an adult patient is usually due to either hyperparathyroidism or malignancy. This patient is suffering from hypercalcaemia most likely
due to renal cell cancer. The treatment options for hypercalcaemia include IV
hydration, calcitonin, bisphosphonates, denosumab, gallium nitrate, prednisone
and haemodialysis.
5. The ECG (Fig.22.18) shows hyperkalaemia. There are tall tented T waves that
are diagnostic of hyperkalaemia.
Chapter 23
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Digitalis Effect andToxicity
Learning Objectives
After studying this chapter, the reader will learn about:
• Digitalis effect
• Digitalis toxicity
23.1 Digitalis Effect
Digitalis (digoxin) is one of the commonest drugs to produce changes in
ECG.Digitalis is water soluble and is highly concentrated in the myocardium. It
inuences the repolarization of myocardium. The serum level of digitalis, at a standard dose, in which no toxicity is seen is 1.0–1.5ng/mL.The ECG change produced
at this level is called digitalis effect. The ECG changes are:
• S-T segment depression
• Decrease in magnitude of T wave
• Decrease in Q-T interval
• Prolongation of P-R interval
23.1.1 S-T Segment Depression
The S-T segment is depressed. The J point remains at isoelectric level. After that the
S-T segment slopes downwards with a sharp terminal rise and blends with the T
wave. This produces the mirror image of a correction mark or reverse check sign
(Figs. 23.1, 23.2, 23.3 and 23.4). The depression of S-T segment has also been
Ltd. 2024
T. K. Koley, Rapid Review of ECG,
https://doi.org/10.1007/978-981-99-9116-7_23
303© The Author(s), under exclusive license to Springer Nature Singapore Pte
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Fig. 23.1 Digitalis effect
23 Digitalis Effect andToxicity
Lead II
25 mm/s. 10 mm = 1 mV
V1
25 mm/s. 10 mm = 1 mV
Fig. 23.2 Digitalis effect. Note the reverse check sign in leads V5 and V6
V2
V3
V4
V5
V6
described as a scooped S-T segment depression. The S-T segment often has a
scooped conguration also. If the J point is also depressed, it indicates digitalis
toxicity. This change is mainly seen in the leads with the tall R waves, i.e. the epicardial leads. If this change is also seen in leads with dominantly negative QRS
complex, then it may be a sign of digitalis toxicity.
23.1.2 Decrease inMagnitude ofT Wave
In digitalis effect, the T wave is slightly diminished in magnitude but the direction
remains unchanged. Along with a depressed S-T segment often the T wave seems to
be dragged down. In digitalis toxicity, the amplitude of T wave is decreased and
often it is inverted. However, it should be kept in mind that the T wave may be
inverted due to preexisting coronary artery disease. In digitalis effect, the T wave is
depressed and rises above the baseline before becoming isoelectric, but in digitalis
toxicity, the T wave does not rise above the baseline. See Fig.23.4. Sometimes digi-
talis may cause slight increase in amplitude of U wave.
25 mm/s. 10 mm = 1 mV
23.1 Digitalis Effect
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IIII
II
aVR aVL aVF
25 mm/s. 10 mm = 1 mV
V1 V2
Fig. 23.3 Digitalis effect. Note the reverse check sign best seen in leads I, II and note the terminal
positivity of the inverted T wave in leads II, V3 to V6
V3
V4
V5 V6
Fig. 23.4 Diagrams of digitalis toxicity and digitalis effect. (A) Reverse check sign. Note the
terminal positivity of the T wave. (B) Scooped S-T segment. The depressed S-T segment is shown
with an arrow. (C) Digitalis toxicity. Note that the terminal part of the T wave does not rise above
the baseline. (D) Digitalis toxicity. Note that the terminal part of the T wave does not rise above the
baseline. The J point is also depressed. It can also be due to primary T wave abnormality due to
coronary artery disease
abc d
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23 Digitalis Effect andToxicity
23.1.3 Decrease inQ-T Interval
Digitalis decreases the duration of electrical systole. The Q-T interval is shortened
in digitalis effect because the refractory period of ventricular myocardium is shortened. This change is seen early during digitalization and does not represent digitalis
toxicity. The refractory period of atrial myocardium is also shortened, but it is difcult to measure directly. It is however important to remember that digitalis
increases the refractory period of SA and AV node.
23.1.4 Prolongation ofP-R Interval
Digitalis causes vagal stimulation which reduces AV conduction. As a result, the
P-R interval is prolonged within the range of 0.02–0.30s. It also slows down the
ventricular rate.
Tips and Tricks
• Look for reverse check sign and scooped S-T segment to diagnose digitalis effect.
23.2 Digitalis Toxicity
The serum level of digitalis is usually more than 2–3ng/mL when the features of
digitalis toxicity appear in the ECG.Hypokalaemia due to diuretic therapy is one of
the most common factors that precipitates digitalis toxicity. The various ECG
changes are:
23.2.1 S-T Segment Depression
There is downsloping S-T segment depression like digitalis effect, but along with it
there is depression of the J point also and there is no terminal positivity of the
inverted T wave (Fig.23.5). The T wave does not rise above the baseline.
23.2.2 Cardiac Arrhythmia
Almost any type of cardiac arrhythmia is seen in digitalis toxicity. The arrhythmias
commonly seen are sinus bradycardia, rst-degree AV block, ventricular extrasystoles (uniform and multiform) and ventricular bigeminy. Wenckebach type of block
may be seen. Complete heart block, SA block, AV dissociation, AV junctional
23.1 Digitalis Effect
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Lead II 25 mm/s. 10 mm = 1 mV
Fig. 23.5 Digitalis toxicity. There is S-T segment depression with reverse check sign. The J point
is depressed with T wave inversion. The terminal part of T wave does not rise above the baseline.
There is pronged P-R interval (0.28s) and the third PQRST complex is missing indicating SA block
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rhythm and ventricular brillation may be observed sometimes. Nonparoxysmal
atrial tachycardia with variable AV block is characteristic of digitalis toxicity. Atrial
utter, atrial brillation and Mobitz type II second degree AV block are the least
likely of all the arrhythmias to be caused by digoxin toxicity. The various ECG
changes in digitalis toxicity are summarized in Box 23.1.
Box 23.1 Changes in Digitalis Toxicity
S-T segment depression (including J point depression)
T wave inversion
Sinus bradycardia
Uniform or multiform ventricular extrasystoles
Ventricular tachycardia, utter and brillation
Paroxysmal atrial tachycardia
SA block
Bundle branch block
First, second and third degree AV block
Atrial utter and brillation
Digitalis toxicity is manifested by anorexia, nausea, vomiting, yellow vision, etc.
The toxicity commonly occurs because of a narrow therapeutic window. Toxicity is
seen when serum level exceeds 2ng/mL.Coadministration of quinidine, verapamil,
amiodarone and propafenone predisposes to toxicity.
Tips and Tricks
• If you nd S-T segment downsloping depression with depression of J point and
T wave inversion think of digitalis toxicity.
• If you nd S-T segment depression with T wave inversion always rule out myocardial ischaemia before considering it a case of digitalis toxicity.
Self-Assessment Questions
1. Digitalis toxicity can result in a characteristic scooped S-T segment depression
in the ECG.True or false?
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23 Digitalis Effect andToxicity
2. Digitalis effect is commonly associated with an increased risk of atrial brilla-
tion in the ECG.True or false?
3. Digoxin toxicity may cause ventricular tachycardia on the ECG.True or false?
4. Digitalis toxicity is precipitated by hyperkalaemia. True or false?
5. Which of the following ECG ndings is typically associated with chronic
digitalis use?
a. Bradycardia b. S-T segment depression c. Presence of J waves d.
Atrioventricular block
6. Which of the following is seen in an ECG in patients with digitalis effect?
a. Prolonged Q-T interval b. Mild prolongation of P-R interval c. Increased
QRS complex duration d. Elevated S-T segment
7. Which ECG abnormality is commonly observed in patients with digoxin
toxicity?
a. Sinus bradycardia b. Sinus tachycardia c. Ventricular brillation d.
Normal sinus rhythm
8. The ECG nding of digitalis toxicity can mimic which cardiac condition?
a. Ventricular septal defect b. Brugada syndrome c. Wolff-Parkinson- White
syndrome d. Acute myocardial ischaemia
9. Digoxin effect can result in the appearance of “reversed tick” or “Salvador
Dali” sign, which is characterized by:
a. Biphasic T waves b. Peaked T waves c. S-T segment depression d. Absent
T waves
10. Digoxin intoxication may lead to:
a. Ventricular bigeminy b. AV junctional rhythm c. Sinus node depres-
sion d. All of the above
Case Studies
1. A 63-year-old gentleman was prescribed some medicine and was taking it for
past veyears. Previously, he was taking it once daily but for last sixmonths he
had been taking it twice daily by mistake. Now he complains of nausea, vomiting
and yellow vision. He had two rhythm strips with him. One strip was recorded
2 years back (Fig. 23.6) and another was recorded 5days back (Fig. 23.7).
Examine both the rhythm strips and make your diagnosis.
2. Examine the rhythm strip given in Fig.23.8. Identify it.
Lead II 25 mm/s. 10 mm = 1 mV
Lead II 25 mm/s. 10 mm = 1 mV
23.1 Digitalis Effect
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Fig. 23.6 Rhythm strip recorded 2years back
Lead II 25 mm/s. 10 mm = 1 mV
Fig. 23.7 Rhythm strip recorded 5days back
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Fig. 23.8 Analyse the rhythm strip
Answers
1. True 2. False 3. True 4. False 5. b 6. b 7. a 8. d 9. c 10. d
Case Studies
1. The patient has complained of nausea, vomiting and yellow vision. This indicates that most likely the patient was taking digitalis. The rhythm strip in
Fig.23.6 shows digitalis effect. There is reverse check sign of downsloping S-T
segment depression. The T wave rises above the baseline. The P-R interval
is 0.22s.
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