Segment 1 Opening credits. Shots of foxgloves growing wild in British woodland. A commentary explains that in 1785 the physician William Withering published his findings of the foxglove as a diuretic, useful in dropsy and having an effect on the heart. In the 1890s Mackenzie furthered this research, his ink polygraph enabled him to record venus and arterial pulses and he found that digitalis was effective in auricular fibrillation. A patient with cardiac failure is shown, with close shots of her irregular pulsation in the neck area. Time start: 00:00:00:00 Time end: 00:04:19:00 Length: 00:04:19:00
Segment 2 On the discovery of digitoxin, gitoxin and finally digoxin. In 1869 digitoxin was isolated - a diagram shows the structure of the molecule, a glycoside. In 1928 gitoxin was discovered - the molecular structure is shown, but this compound was too insoluble to be useful. Digitalis Lanata was found to have very high concentration of these glycosides and in 1929 further research was carried out at the Wellcome chemical works. The process of extracting the glycosides from Digitalis lanata at the Wellcome chemical works is shown and separation by repeat recrystalisaton from various solvents is demonstrated. Fractions are examined and a third substance found, digoxin, the molecular structure of which is shown. Large scale production of digoxin begins. We see Digitalis Latana growing in fields and the harvesting of the leaves. Pure digoxin is produced and then made ready for clinical use. There are production line shots of ampoules and tablets; routine tests to ensure batch purity are shown. Time start: 00:04:19:00 Time end: 00:10:34:09 Length: 00:06:15:08
Segment 3 Pharmacology and clinical use. Diagrams of the heart showing the contraction and conduction mechanism and laboratory scenes of a rabbit heart set up in a warm chamber with ventricles contracting. Digoxin is introduced and the ventricular contractions are shown to increase. The experiment is carried out on isolated rabbit auricles, whereby artificial heart failure is brought about, digoxin is introduced and contractions increase. It is inferred that digoxin brings about increased energy utilisation in the heart muscle. This action is valuable in congestive heart failure. Time start: 00:10:34:09 Time end: 00:14:34.03 Length: 00:03:59:23
Segment 4 The slowing of conduction by digoxin is shown on a frog heart, toxic levels are given, affecting the rhythm of the heartbeat until it eventually stops. A mammalian heart has similar results from digoxin but leads to ventricular fibrillation in the terminal stage. Clinical doses of digoxin are given, introducing a delay as the wave passes from auricle to ventricle, not affecting the heart rhythm, although the delay appears on an electrocardiogram. Time start: 00:14:34.03 Time end: 00:18:09:00 Length: 00:03:34:26
Segment 5 This clip shows the clinical use of digoxin. Animated diagrams show the effect of the same dose on a heart with auricular fibrillation, digoxin slows the contraction so that the ventricles can be properly filled between beats. Digoxin is especially useful in congestive heart failure, auricular fibrillation and auricular flutter, and paroxysmal tachycardia. A patient with congestive heart failure after hypertension is shown - the venus congestion in the neck is seen and oedema on the legs. She is given digoxin and after four days the venus congestion has disappeared and the oedema cleared completely. Time start: 00:18:09:00 Time end: 00:23:13:01 Length: 00:05:04:01
Segment 6 Side effects of an overdose of digoxin are outlined. Another patient with severe congestive heart failure is seen in respiratory distress, her jugular veins are engorged and the pulsation irregular. She is given digoxin intravenously. A few weeks later she looking well and is shown painting watercolours at home. Various close shots of Digitalis Lanata. Time start: 00:23:13:01 Time end: 00:25:24:24 Length: 00:02:11:22