MEDICATIONS THAT AFFECTS YOUR ECG-1

DIGOXIN

Brand Name:Lanoxin,Digitek

Digoxin is the drug that is used frequently to patients suffering from Congestive Heart Failure.

Digitalis Lanata or purpura is a foxglove plant that gives many glycosides out of which digoxin is the drug more commonly used for CHF.

Nowadays this drug is replaced by many second and third-generation drugs because of its serious side effects.
Digoxin increases the contractility of the heart muscles by Na+/Ca++ ion exchanges.

Digoxin toxicity can be easily studied through ECG. Its toxicity on the heart would be reflected in ECG.

SEE THE ST-SEGMENT DEPRESSION

See in the above figure the ST-segment depression which is the main effect of digoxin. Digoxin causes calcium to build up in the myocytes which cause a slow down of the heart rate (chronotropic) but increases the strength of the contraction (inotropic). The toxic dose of the digoxin leads to an ischemic effect (angina) and that is reflected in ECG as the ST-segment depression.

Digoxin may give the wrong impression in ECG taken in a person with angina on exercise. It gives a normal ST impression instead of depression.

Digoxin Toxicity:-

1.Fatigue, tiredness, and malaise

2.Visual disturbances              

3.Nausea and Vomiting           

4.Digestive problems

5.Abdominal Pain                 

ECG READING EXERCISES-L-MODEL ECG IN CONGESTIVE HEART FAILURE

ECG IN CHF

Note in the above figure the enlarged right and left ventricles. This is the main cause for CHF
CHF is a condition in which the heart is unable to pump the blood sufficiently to the metabolic demand of the body.

Causes:-                               

1.Heart Attack.

2.High B.P

3.Arrhythmia (tachycardia, bradycardia)

4.Defective heart valves

The above causes may either impair the blood output by weakening the heart muscle  (Arrhythmia and Heart Attack) or impose heavy workload on the heart by increasing arterial resistance (Hypertension)

Symptoms:-

1. Left-sided CHF causes lung enlargement, and dyspnea(difficult breathing)

2. Right-sided CHF causes liver enlargement and peripheral edema.

Complementary Physiologic Mechanism:-

1.Increased heartbeat(Adrenergic domination)

2.Reduced kidney blood supply that causes increased salt retention by aldosterone.

3.Enlarged heart(Myocardial Megaly)

Model ECG in CHF:-

Fig-1

In the Fig-1 two models of ECG, rhythms have been shown. One is normal and the other is recorded in CHF. Both are in lead-II.
Usually heart failure can be diagnosed by X-ray which can clearly picture out the enlarged heart.
In ECG this enlarged ventricles can be identified by the uptrend elongated tall R-wave and a widened QRS complex as shown in above Fig-1 by the green lines and the red circles. The QT-interval is also widened which is marked by blue lines in the above Fig-1.
Correction Options:-
1.Improve heart muscle contracting ability

2. Reduce Preload.
3. Reduce arterial resistance after load.
Medicines:-
1.Cardiac Glycosides (Digoxin)
2.Bipyridines
3.Beta-blockers
4.ACE-Inhibitors
5.Vasodilators
6.Diuretics.Continued...