1.ATENOLOL(TENORMIN), PROPRANOLOL(INDERAL) AND CALCIUM CHANNEL BLOCKERS(CCB)
Atenolol is a B.P medicine commonly available in the pharmacy under the brand name as Tenormin.
It is technically known under the group as a Beta Receptor Blocker or simply as Beta Blocker.
Briefly we can say that beta-blockers are drugs that lower the blood pressure by lowering the heart rate by blocking beta-1 receptors of the adrenergic nervous system which is more concentrated on the cardiovascular network. The result also included dilation of the blood vessels and reduction of the heart rate.
This drug has notable effects on the ECG if overdosed.
A normal heart rhythm has been shown diagrammatically in Fig-1 above. In that, the waves P, Q, R, S, and T are clear and distinguishable.
Atenolol is a safe B.P medicine with a wider therapeutic index. It is highly water-soluble and is eliminated in the urine. It is less fat-soluble and hence it is less likely to pass into the blood-brain barrier to produce CNS effects.
But as with any other medicine if overdosed or misused by otherwise a normal person atenolol propranolol and any other beta-blocker will reduce heart rate, blood pressure followed by fatal CHF. This can be noticed in the ECG by prolonged PR segment, wider QRS complex, and elevated or depressed ST segment.
This drug has notable effects on the ECG if overdosed.
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| Fig-1 |
Atenolol is a safe B.P medicine with a wider therapeutic index. It is highly water-soluble and is eliminated in the urine. It is less fat-soluble and hence it is less likely to pass into the blood-brain barrier to produce CNS effects.
But as with any other medicine if overdosed or misused by otherwise a normal person atenolol propranolol and any other beta-blocker will reduce heart rate, blood pressure followed by fatal CHF. This can be noticed in the ECG by prolonged PR segment, wider QRS complex, and elevated or depressed ST segment.
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| Fig-2
In Fig 2 above a model, ECG has been shown with the effects of all beta-blockers such as atenolol, propranolol(Inderal), metoprolol(Lopressor)and calcium channel blockers such as diltiazem(Dilzem, Cartia), verapamil(Isoptin), amlodipine(Norvasc) and nifedipine(Procardia).
In the above ECG examine the lead-II the master lead record which shows the depressed ST segment, with a more depressed S-wave, and the absence of Q-wave.
The aVL record shows (marked by a small red squire) the absence of P, and T-wave and elongated P-R and S-T segments or intervals.
This indicates severe bradycardia (reduced heartbeat)
extremely low pressure and congestive heart failure (CHF)
 Fig 3A |
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| Fig 3B
In the above two diagrams (Fig 3A and 3B) the effects of verapamil (Isoptin) a CCB drug on ECG taken in an old man who has been overdosed by the drug.
In Fig 3A a simulated image has been explained.
Note down the marked deviation of Phase-0 more towards the right. This is because calcium channels are blocked and the entry of calcium is restricted with the result of the shortening of the plateau Phase-2.
The deviation has been explained in the down by elongated PR-interval widening of the QRS complex and the elongated ST-segment.
These changes can be easily noted in Fig-3B in the Lead-II records. The elongated intervals and segments and the QRS widening are marked by a blue rectangle.
Conclusively the ECG effects of both beta-blockers and CCBs are similar by many factors such as elongated PR-intervals, widened QRS-complex, elongated ST-segment, etc which indicates sinus bradycardia followed by CHF. Thank You |
