Diagnostic criteria

  Heart rate > 100/minute.

  P wave is positive in D1 and D2.

  Every P wave is followed by a QRS complex.



About heart rate

  Heart rate increases from birth to the end of the 1st month; then it starts to decrease again.

  Since they have a high resting heart rate, sinus arrhythmia is rarely seen in NEWBORNs.

  Sinus arrhythmia is more common in children and adolescents.

  In the awake state, the normal range of heart rate in children is

            91-166 /minute in the first week of NEWBORNs.

            107-180 /minute at the end of the first month.

            89-151 /minute at the end of the first year.

  In an agitated or crying newborn, the heart rate may increase up to 220/minute.

  A heart rate
above 220/minute is always abnormal.



Causes of sinus tachycardia

  Hypoxia

  Hypovolemia

  Anemia

  Infection

  Fever

  Anxiety

  Decompensated heart failure



Clinical significance of sinus tachycardia

  Usually, there is an underlying cause of the sinus tachycardia.

      Treatment of the underlying cause is usually sufficient for the disappearance of the sinus tachycardia.

  Very rarely, there is no obvious cause for sinus tachycardia:
Inappropriate sinus tachycardia .

  If the patient complains of palpitation and the diagnosis is inappropriate sinus tachycardia,

      then heart rate can be decreased by the use of a beta blocker, diltiazem or verapamil.

      Such a therapy may also prevent the possible development of tachycardia-induced cardiomyopathy.




Caution

  If you cannot see P waves, do not diagnose sinus tachycardia.

  If there is a
regular tachycardia with narrow QRS complexes, the heart rate (ventricular rate) is

      about
110-130/minute and P waves are not easily noticeable, then check for the presence of

     
atrial flutter with 2:1 block.

      In such a case, look for evidence of "
sawtooth appearance" in descending half of T waves.

      In such a case, intravenous Adenosine administration may be helpful. Adenosine will result in a

      transient increase in atrioventricular (AV) block and may reveal the presence of flutter waves.

  If there is a
regular tachycardia with narrow QRS complexes, the heart rate (ventricular rate) is

      about
110-130/minute and P waves are not easily noticeable, then check for the presence of

     
ectopic atrial tachycardia with block.

      In such a case, do NOT expect to see "
sawtooth appearance".

      In such a case, intravenous Adenosine administration may be helpful. Adenosine will result in a

      transient increase in atrioventricular (AV) block and may reveal the presence of ectopic P waves.





ECG 1. Sinus tachycardia is seen above. P wave rate (atrial rate) is about 120/minute.





ECG 2. The above ECG belongs to a 22 years-old man who had received chemotherapy for AML.
ECHOcardiography showed dilated left ventricle and left atrium with depressed left ventricular systolic function
(low Ejection Fraction).
The rhythm is sinus tachycardia with a
heart rate of 136/minute.
P waves and an acceptable PR interval are seen.

Click here for a more detailed ECG





ECG 3a. The ECG above belongs to a 68 years-old man with Chronic Obstructive Pulmonary Disease (COPD).
He complains of dyspnea which worsened, recently.
His ECHOcardiogram showed normal left ventricular systolic function (normal Ejection Fraction).
The narrow QRS rhythm above has a
heart rate of 123/minute.
Is it sinus tachycardia?
Do we see P waves in lead V1?
The deflections in lead V1 cannot be P waves since they do not have an acceptable PR interval.
This ECG was recorded
just before intravenous injection of 10 mg Adenosine.
The recording time is 10:09:39.

Click here for a more detailed ECG




ECG 3b. The above ECG belongs to the same patient and shows the onset of Adenosine effect.
It was recorded at 10:10:38 and shows the rhythm one minute after the ECG 3a.
Adenosine injection results in atrioventricular (AV) block and
heart rate (ventricular rate) slows down.
When
heart rate (ventricular rate) slows down, flutter waves become clearly visible.
This is atrial flutter. The rhythm in ECG 3a was atrial flutter.
When you see a regular narrow QRS tachycardia with a heart rate (ventricular rate, QRS rate) of 110-130/minute
but with no clearly identifiable P waves, remember the possibility of atrial flutter.

Click here for a more detailed ECG




ECG 3c. The above ECG belongs to the same patient and shows disappearance of Adenosine effect.
It was recorded at 10:10:49 (10 seconds after the ECG 3b).
With the disappearance of Adenosine effect,
heart rate (ventricular rate) increases again.
With the disappearance of Adenosine effect,
flutter waves become difficult to notice.

Click here for a more detailed ECG





ECG 4. The ECG above belongs to a 37 years-old man with overt anxiety.
Heart rate (ventricular rate) is 132/minute.
No sawtooth appearance is seen. The rhythm is
sinus tachycardia.
P waves and (acceptable) PR interval are clearly seen.
On the other hand, the ECG 3a did not show clear P waves even though the heart rate was 123/minute.

Click here for a more detailed ECG





ECG 5. The ECG above belongs to a 79 years-old man with chronic obstructive pulmonary disease (COPD).
His heart rate (ventricular rate) is 122/minute.
Now, what do you think about the rhythm in the above ECG?
Do you see clear P waves and (an acceptable) PR interval?
Do you see sawtooth appearance (
or at least some evidence of it)?
:))
It's clear, isn't it?

Click here for a more detailed ECG





ECG 6. The ECG above is from a 35 years-old man with atypical resting chest pain.
Heart rate (ventricular rate) is 122/minute.
P waves and (acceptable) PR interval are clearly seen.
Sawtooth appearance is not seen.
The rhythm is sinus tachycardia.
Many leads show
PR depression while lead aVR shows PR elevation.
The clinical and ECG findings of this patient suggested the diagnosis of pericarditis.

Click here for a more detailed ECG





ECG 7. The ECG above is from a 47 years-old man.
Heart rate (ventricular rate) is 148/minute.
P waves and PR interval are clearly seen.
Even though the heart rate is high (148/minute),
P waves are still seen.
Sawtooth appearance is not seen.
The rhythm is sinus tachycardia.

Click here for a more detailed ECG





ECG 8. The ECG above is from a 27 years-old man with chronic renal failure.
It was recorded a few hours after renal transplantation.
At the same time, his serum potassium level was measured as 5.1 mEq/L.
The rhythm is sinus tachycardia. The
T waves and the P waves are clearly visible.

Click here for a more detailed ECG





ECG 9a. The ECG above belongs to a 85 years-old woman with coronary artery disease.
She complains of palpitation. Right bundle branch block is seen.
The heart rate is 121/minute. What is the rhythm?
Is it sinus tachycardia? Can you see the P waves?
Do you think that the PR interval is normal? Is it sinus tachycardia?
At a ventricular rate of 121/minute, it is easy to misdiagnose this rhyhtm as sinus tachycardia, at first glance.

Click here for a more detailed ECG




ECG 9b. The ECG above belongs to the same woman.
It was recorded 30 seconds after the ECG 9a.
What is the rhythm?
Do you see the P waves? Do you think that the PR interval is normal?
Do you think that there is sawtooth appearance?

Click here for a more detailed ECG




ECG 9c. The above rhythm tracing belongs to the same woman.
It was
recorded at a calibration of 20 mm/mV to better see the details.
P waves are clearly seen. Atrial rate (P wave rate) is 240/minute.
Not all P waves are conducted to ventricles. This is
ectopic atrial tachycardia with block.
This is not atrial flutter, there is no sawtooth appearance: a flat baseline between the P waves is seen.
Since frequent temporary increases in AV block level revealed ectopic P waves, we did not need to use Adenosine
in this patient.

Click here for a more detailed ECG




ECG 9d. The above rhythm tracing belongs to the same woman.
It was
recorded at a calibration of 10 mm/mV
P waves are seen. Not all P waves are conducted to the ventricles.
This is
ectopic atrial tachycardia with block.
Since frequent temporary increases in AV block level revealed ectopic P waves, we did not need to use Adenosine
in this patient.

Click here for a more detailed ECG