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To The Editor:Although the title is ABC of ECG, and reflects an
approach as though one is learning the alphabet in elementary school,
there are certain important basic medical conditions that affect the ECG,
not clearly defined in these papers in the BMJ.
1- High levels of serum potassium(5-7meq/l) usually produce
peaked T waves and diminished QRS voltage with IVCD.
At 8-10meq/l, the P wave may disappear and the QRS may become widened
simulating a sine wave(1). Clinically hyperkalemia is noted in end
stage renal and other conditions.
2- Low levels of serum potassium(3-2meq/l): The T wave is of low voltage
with a prominent U wave. Clinically noted in severe diarrhea, addisons,
aldosteronism, diuretic therapy etc.(1)
3- Low and high serum calcium levels also affect the QT interval.
4- Class 1A drugs(quinidine, procainamide etc) influence the duration of
the QT interval. Also tricyclics antidepressants and class 111
drugs(amiodarone,sedatole)(2).
5- Other clinical situations have definite ECG patterns such as
stroke(hemorrahge) and generalized body hypothermia(2).
6- Finally, pericadial tamponade and emphysema produce low QRS voltage,
and the latter poor R wave across the V leads(2).
References: 1-Sodi-Pallares et al,Electrcardiography and
Vectorcardiography in Clinical Cardiopulmonary Physiology.
2nd edition., New York: Grunn and Stratton, 1960.
2- Personal observations, and from various sources collected
from the medical literature, lectures etc.
Competing interests:
No competing interests
26 May 2002
Munir E Nassar, M.D.
consultant physician
17 Cobblefield Way, Pittsford, New york 14534-2566
Metabolic and other conditions affecting the ECG
To The Editor:Although the title is ABC of ECG, and reflects an
approach as though one is learning the alphabet in elementary school,
there are certain important basic medical conditions that affect the ECG,
not clearly defined in these papers in the BMJ.
1- High levels of serum potassium(5-7meq/l) usually produce
peaked T waves and diminished QRS voltage with IVCD.
At 8-10meq/l, the P wave may disappear and the QRS may become widened
simulating a sine wave(1). Clinically hyperkalemia is noted in end
stage renal and other conditions.
2- Low levels of serum potassium(3-2meq/l): The T wave is of low voltage
with a prominent U wave. Clinically noted in severe diarrhea, addisons,
aldosteronism, diuretic therapy etc.(1)
3- Low and high serum calcium levels also affect the QT interval.
4- Class 1A drugs(quinidine, procainamide etc) influence the duration of
the QT interval. Also tricyclics antidepressants and class 111
drugs(amiodarone,sedatole)(2).
5- Other clinical situations have definite ECG patterns such as
stroke(hemorrahge) and generalized body hypothermia(2).
6- Finally, pericadial tamponade and emphysema produce low QRS voltage,
and the latter poor R wave across the V leads(2).
References: 1-Sodi-Pallares et al,Electrcardiography and
Vectorcardiography in Clinical Cardiopulmonary Physiology.
2nd edition., New York: Grunn and Stratton, 1960.
2- Personal observations, and from various sources collected
from the medical literature, lectures etc.
Competing interests: No competing interests