Atropine , the extract from the Belladona plant is an important cardiovascular drug. It’s presence is vital in every crash carts . This unassuming molecule probably has saved more cardiac lifes than any other drug . It provides immediate remedy for many of the bradycardias .It works like a magic. The physician buys time with this molecule and proceed on to resuscitate or plan other interventional procedures. It is most powerful antiarrhytmic agent known .It is an irony , many of the standard cardiac texts do not even mention this while discussing anti arrhythmic agents .
In this era of hyped cardiac care , the sartans , 2b3a inhitors , the fondaparinux’s making merry ! we have no spare time to realise , more cardiac deaths have been prevented by atropine than all these drugs put together. It is still working like a bull across the coronary care units and cath lab world over. While many mediocre drugs enjoy a big bash time for possibly saving few occasional lives , the atropine like drugs never get the due recognition among cardiac literature for the simple reason , it being a cheap generic drug.This drug is available for few rupees , no marketing no advertisements, no celebrations.
Mechanism of action
The biochemical mediator : Acetyl choline
Site of action : It blocks the M2 (Muscaranic receptors) .
We will confine to the cardiovascular actions.
- SA nodal acceleration
- AV nodal accelerated conduction
Effect on ECG
Short PR interval
Life saving situations in cath labs in CCU.
Vagus nerve richly innervate the heart and blood vessels . Acute coronary syndromes especially involving the infero posterior territory raises the vagal tone , and can in severe bradycardia and hypotension. In cath labs , as we manipulate cardiac structures with wires and catheters there is always a potential to elicit the vascular reflex .It can occur any where between the access point , femoral or radial artery to coronary arteries .
Further , whenever the pain intensity is more , the central pain integrating centre in brain stem and thalamus has a spill over effect into the vagal nucleus .
What happens if a vaso vagal reaction is left untreated ?
We have often made the term “vaso vagal reaction” appear as an innocuous entity. The main reason for this perception is due to the common occurrence of “vaso vagal syncope” which is largely a benign entity in the general population .This fact has sensitised our brains . One should distinctly realise the vaso vagal syncope that occurs in healthy people standing in erect posture , from vagal reactions that occurs in lying patient with a diseased heart in a cath lab or CCU.In the classical vaso vagal syncope , assuming the recumbent posture is the treatment and it counters the hemodyanmic imbalance .No drug is required here. So the common vagal syncope can never be compared with potentially dangerous vagal reflex that occur in CCUs and cath labs. If not recognised earlier and immediately countered it can lead on to asystole and death .Many of the delayed deaths post PCI during sheath removal or an episode of vomiting are directly related to this.
Atropine is the Savior here . Can you imagine a world without atropine .
The other reason we had always considered vaso vagal reactions lightly is that the poor atropine is always available in the side selfs and it acts rapidly and promptly with almost 100 % success reversing the vagal action in less than 60 seconds .
How often we here this “Oh it’s a brady . . . push 2cc atropine . . . given sir, the rate has picked up . . .”
If only atropine has a failure rate of say 50% we would have realised the full impact of vaso vagal shocks (See … how we struggle with No reflow with no effective drug available !)
Is there any other alternative treatment for vaso vagal shock other than atropine ?
No. (I guess so . . .Readers may correct me )
Other uses of atropine in cardiac practice
- During stress testing along with dobutamine to increase the heart rate.
- It can be used to differentiate AV blocks the two types of 2nd degree AV block. The mobitz type 2 worsens while type one accelerates.
Non cardiac uses.
Ophthalmology, pre anesthetic medication, bronchial asthma, various poisoning.
What is the future for this molecule ?
Remain bright . But only very few companies make this molecule. It is a drug that can not fill the cash boxes but it is a drug to keep the human heart running at times of crises . The only threat to this drug is the possibility of it being replaced with a modified patented version of this great molecule !
The evolution of medicine is based on strong foundations put upon by clinical acumen by great medical men of past generation. Atropine was developed by such people and it has withstood the test of time. This drug probably has saved ( and continue to save) many lives than any other drug in cardiology . It should be recalled , another great cardiac drug called digoxin has almost succumbed to modern medical forces .Let us keep developing new molecules , we shall also pay tributes to some of the unassuming drugs in cardiology .