Translation guide
The medical condition where the heart cannot pump enough blood. In Japanese, the standard term is 心不全 (shinfuzen). The more dramatic 'heart attack' is a different concept (心臓発作).
The chronic or acute inability of the heart to pump sufficient blood.
Standard medical term for heart failure. Used in both formal and everyday contexts.
父は心不全で入院しました。
My father was hospitalized for heart failure.
Literally 'the heart is weakened'. A more colloquial way to describe the condition, often used in conversation.
祖母は心臓が弱っていて、あまり動けません。
My grandmother has heart failure and can't move around much.
More technical phrasing, 'cardiac insufficiency'. Used in medical reports or formal explanations.
心臓の機能不全が進行しています。
The heart failure is progressing.
Heart failure (心不全) is not the same as a heart attack (心臓発作 or 心筋梗塞). Using 心臓発作 for chronic heart failure will cause confusion.