T wave alternans (TWA) is a periodic beat-to-beat variation in the amplitude or shape of the T wave in an electrocardiogram TWA was first described in 1908. At that time, only large variations could be detected. Those large TWAs were associated with increased susceptibility to lethal ventricular tachycardias.
Electrical alternans is an electrocardiographic phenomenon of alternation of QRS complex amplitude or axis between beats and a possible wandering base-line. It is seen in cardiac tamponade and severe pericardial effusion and is thought to be related to changes in the ventricular electrical axis due to fluid in the pericardium, as the heart essentially wobbles in the fluid filled pericardial sac.
Pulsus alternans is a physical finding with arterial pulse waveform showing alternating strong and weak beats. It is almost always indicative of left ventricular systolic impairment, and carries a poor prognosis.
Grandisonia alternans is a species of caecilian in the family Indotyphlidae, endemic to the Seychelles islands of Mahé, Praslin, Frégate, and La Digue.
Philbertia alternans is a species of sea snail, a marine gastropod mollusk in the family Turridae.
Calosoma alternans is a species of ground beetle in the subfamily of Carabinae. It was described by Johan Christian Fabricius in 1792.
Cymindis alternans is a species of ground beetle in the subfamily Harpalinae. It was described by Rambur in 1837.
Orthogonius alternans is a species of ground beetle in the subfamily Orthogoniinae. It was described by Wiedemann in 1823.
Onciderini is a tribe of longhorn beetles of the Lamiinae subfamily.
Megachile alternans is a species of bee in the family Megachilidae. It was described by Friese in 1922.
Agapanthia alternans is a species of beetle in the family Cerambycidae. It was described by Fischer von Waldheim in 1842.
Mimosybra alternans is a species of beetle in the family Cerambycidae. It was described by Breuning in 1973.
Sybra alternans is a species of beetle in the family Cerambycidae. It was described by Wiedemann in 1823. It is known from Myanmar, Thailand, Laos, Cambodia, Vietnam, Malaysia, Taiwan, Indonesia, Mariana Islands, Caroline Islands, Marshall Islands, and the Philippines. It was introduced in Hawaii in 1917, as well as Florida. Its diet includes plants such as Ananas comosus, Canavalia ensiformis, Musa × paradisiaca, Ocimum basilicum, Phaseolus vulgaris, Pittosporum tobira, Vachellia farnesiana, and Xanthium strumarium.
Melanothrix alternans is a moth in the Eupterotidae family. It was described by Pagenstecher in 1890. It is found in the Philippines (Palawan) and on Borneo. The habitat consists of hill dipterocarp forests and wet heath forests.
Clivina alternans is a species of ground beetle in the subfamily Scaritinae. It was described by Darlington in 1971.
Cremnosterna alternans is a species of beetle in the family Cerambycidae. It was described by Stephan von Breuning and Itzinger in 1943.
Sternotomis alternans is a species of beetle in the family Cerambycidae. It was described by Stephan von Breuning in 1959.
Brachinus alternans is a species of ground beetle in the family Carabidae. It is found in Central America and North America.
Egira alternans, the alternate woodling, is a species of cutworm or dart moth in the family Noctuidae. It is found in North America.
Temnostoma alternans is a species of syrphid fly in the family Syrphidae.
