 Lung Doppler signals will be recorded in sitting position from selected locations over the right chest wall. If the subject is unable to sit in a chair, the headrest of the patients bed will be tilted upwards to about 45 degrees. Regarding the decompensated left HF patients, the first measurement of LDS will take place as soon as possible after admission to the emergency medicine department, providing the patient has been adequately treated and stabilized and is willing and able to sign an informed consent form. The LDS measurement will be repeated twice more at the EMD at 1 hour intervals. LDS will be recorded only once for the compensated patients and the non-CHF controls. 