1902-1904

Mackenzie, in association and with support of Dutchman Karl Wenckebach and fellow Scotsman Sir Arthur Keith (who dissected Mackenzie’s hearts at London Hospital), documents and explains ventricular extra-systole as cause of continuous heart irregularity. In Inception of the rhythm of the heart by the ventricle as the cause of continuous irregularity (BMJ, 1904), Mackenzie concluded that “when the rhythm of the heart originates at the auricles, or at the auricular mouths of the veins, it is always regular. When, however, the ventricle takes on the inception of the rhythm the heart is always irregular” (Mair, 123ff; quote at 134).