Background: Patients with heart failure (HF) often inadequately perceive their symptoms. This may be because the medical terms do not match the somatic changes experienced by patients. To improve symptom perception, healthcare professionals must understand the somatic changes as perceived by patients. Objective: This study aims to analyze patients' narratives about somatic changes in patients with HF by text mining and to clarify the overall description of somatic changes using patients' expressions. Methods: Semistructured interviews were conducted on 21 patients hospitalized for acute exacerbation of HF. Qualitative data obtained from the interviews were analyzed by content analysis through text mining. Results: Among the 21 patients, 76.2% were men. The mean (SD) age was 71.3 (13.7) years. The most frequently used terms were "breath," "distressed," "feet," and "ha-ha (gasping sound)" (46, 40, 29, and 28 times, respectively). The somatic changes noticed by patients could be categorized into medical jargon such as "dyspnea on exertion," "exercise intolerance," "fatigue," "paroxysmal nocturnal dyspnea," "frequent urination," "increased sputum," "weight gain," "feet and face edema," "abdominal edema," and "ankle edema." However, the expressions of somatic changes used by the patients were diverse. Conclusions: The findings of patientspecific expressions of symptoms suggest that there is a need to assess symptoms not only using medical jargon but also by focusing on patient-specific expressions.