Dr.S.Venkatesan MD

Bradycardia is a common cardiac arhythmia. Sinus bradycardia  is  often considered an arrhythmia from a disciplined heart. It denotes high vagal tone .  A  heart rate  of  40 , some times even 35 is well tolerated . But bradycardia due to heart blocks are dangerous.

Sinus bradycardia can not get lower than 30/mt or so , as invariably either the  junction or the  ventricle , escapes with its own rhythm. Near syncope, dizziness , giddiness followed by  syncope  occur as the  heart rate  slows progressively below this level .It is often taught humans can not survive  when the heart  rate  goes below 10/mt .

Case report :

Here is middle-aged man who  presented  with a history of  recurrent syncope over a period of  3 days . He has no  history of CAD.

As he entered  the ER, this ECG was recorded.

At this pint of time  , when the ECG was recorded,  he was  conscious and talking ,  only to complain  of  little dizziness. After seeing this ECG , he was immediately put on a  temporary pacemaker.

Note : The ECG shows a single qrs complex per tracing of 10  sec duration .Ie HR of 6 /mt.One qrs complex for 50 large squares !  .Divide  300/50 and HR is 6 . Note also the p waves fire at 150/mt due to atropine effect .

The procedure  took 15 minutes to perform  , he was comfortable  and was administered atropine , and isoprenaline *, which increased his heart rate  from  6/mt to 10/mt .

Later he went on to receive a permanent pacemaker a week later.

* Temporary trans-cutaneous pacing using paddle stickers  is  an another  modality available in such situations where trans-venous pacing is  likely to be delayed  .

Message from this case

Cardiology’s  ultimate  moment of glory and truth  is experienced  when a  life  is saved with  a pacemaker.

Extreme bardycardias are  often  fatal , but here is a patient with  dangerously  low heart rate , still not resulting in asystole  or brady induced VT/VF . We had adequate  time to plan a strategy . Severe bradycardias  need not result in cardiac  arrest always.  Some hearts  have amazing capacity   and their  fighting spirit   amazes  us !  .It should be noted that , the above example may be  an exception than a rule .