One morning during my routine rounds I got a call from the causality. The resident was panicking and I could almost hear his heartbeat through the phone!
He said “madam there is a patient here, who is 64yrs, brought with sudden loss of consciousness. Has no chest pain or sweating but has been having a few similar episodes like this in the last 6 months. This time the episode is a bit prolonged and he hit his head on the ground while he fell down.
I rushed to the ER and found him conscious but a bit drowsy. His heart rate was at 40/min, other vital parameters were normal.
We went ahead with the ECG and found that it showed a complete heart block. We explained to the relatives about the disease and the appropriate treatment for the same. A look of suspicion and disbelief was quite evident from the face of his son !
Despite explaining the pathology and the cause of the same, he had a plethora of doubts as to whether it is a heart attack, whether angiogram needs to be done, stents etc, etc.
This lack of awareness is what prompted me to write this…
What is bradycardia?
The heart missing a beat and maidens sooning may be romantic in literature but nightmarish to a cardiologist!
It simply means a low heart rate. By definition it is a heart rate below 60/min. There are innumerable innocuous conditions which can cause bradycardia.
This could be because one is an athlete or one does regular exercise by which the heart pumping is very efficient and the stroke volume is high. It could be due to various other reasons like hypothyroidism or certain drugs like beta blockers.
The ones which require attention are those which lead to recurrent loss of consciousness, often associated with injury. The cardiac causes for the same include dysfunction of the sinus node and AV node
When is bradycardia significant?
Bradycardia is said to be significant, if it is associated with symptoms like loss of consciousness, excessive tiredness, giddiness etc
How is it diagnosed and evaluated?
A block in the impulse formation and conduction anywhere along the conduction system can lead to heart blocks. A disorder in the impulse formation leads to sinus node dysfunction and varying degrees of conduction problems along the conduction system causes atrioventricular (av blocks).
The basic investigations include ECG, Echocardiogram and 24 hour ECG monitoring (holter). After getting a diagnosis from the ECG, if the rate is very low and the patient is drowsy like in the case which I mentioned earlier, an emergency temporary pacing lead is placed inside the heart via a vein via the groin or the neck.
A temporary pacing circuit
Once the temporary lead is in position, certain parameters are checked which may reverse the underlying condition.
For instance, stopping a drug which can cause bradycardia, checking for electrolytes and correction if required. If no correctable cause is identified, the patient needs to undergo a permanent pacemaker implantation.
The procedure is done under local anesthesia, with a small pocket near the left collar bone, which is the battery compartment.
The leads are connected to the chambers inside the heart through veins (subclavian veins). The leads are screwed inside the heart and the other end of the lead is connected to the battery.
The advice given should be strictly adhered to or else it can lead to several complications.
Further follow up of the pacemaker can be done with a magnet placed over the device using a pacing system analyser (PSA). This is done as an outpatient procedure, at specified intervals as directed by the physician
Pacemaker implantation is a routine procedure done with a certain amount of expertise in the field. The procedure carries only as much risk as any other cardiac procedure. The patient needs to be fully compliant with instructions given by the physician during the implant as well the post implant period.
Special issues like obtaining an MRI scan while on a device, can be addressed to the physician.
Most of the current generation of pacemakers are designed to be MRI compatible if that property is installed in the device. The decision regarding the same can be made at the time of implant.
Rapid advances on a day to day basis is happening to this technology. Pacemakers without leads, remote monitoring systems in pacemakers, advanced heart failure devices (CRT) and implantable defibrillators(ICD) are readily available.
In short pacemakers are the “pace setters” of the heart. A timely implantation can save many lives.