Okay, let's tackle this question. The patient is a 30-year-old woman with sudden onset of breathlessness, anxiety, palpitations, and a feeling of impending doom. Physical exam is normal. The key here is to figure out the most likely diagnosis.

First, I need to consider the symptoms. Sudden onset of these symptoms, especially the feeling of impending doom, makes me think of a panic attack. Panic attacks often present with these symptoms and can occur without any physical cause. The physical exam being normal supports this because there's no underlying organic issue like a heart attack or pulmonary embolism to be found.

But wait, other differentials come to mind. Anxiety disorders vs. panic attacks. Also, maybe hypoglycemia, but there's no mention of sweating or hunger. Hyperthyroidism could cause palpitations, but again, the physical exam is normal. Maybe a cardiac issue like arrhythmia, but the exam is normal, so maybe not. Pheochromocytoma? That can cause episodic palpitations and anxiety, but again, the physical exam would show signs like hypertension.

The core concept here is recognizing the classic presentation of a panic attack. Panic attacks are characterized by sudden episodes of intense fear that trigger severe physical reactions when there is no real danger. The DSM-5 criteria include symptoms like palpitations, sweating, trembling, shortness of breath, and a fear of losing control or dying.

The correct answer is likely panic attack. The other options are less likely because they either present with different symptoms or have physical findings. For example, a myocardial infarction would have chest pain and possibly abnormal EKG, which isn't mentioned here. Hyperventilation syndrome can cause similar symptoms, but it's usually due to excessive breathing leading to respiratory alkalosis, which might not be as sudden. Also, the feeling of impending doom is more specific to panic attacks.

So, the key points are the sudden onset, the specific symptoms, and the normal physical exam. The clinical pearl here is to remember that panic attacks can mimic other conditions but the presence of a normal exam and the specific constellation of symptoms point towards it.

**Core Concept**
This question tests recognition of **panic disorder** as a cause of acute somatic and psychological symptoms in a young, otherwise healthy individual. Key features include sudden onset, autonomic hyperactivity (palpitations, breathlessness), and a normal physical exam, distinguishing it from life-threatening conditions like myocardial infarction or pulmonary embolism.

**Why the Correct Answer is Right**
Panic attacks are defined by **sudden, intense fear** with peak severity within minutes, accompanied by symptoms like palpitations, dyspnea, chest pain, and a sense of impending doom. These episodes are **not linked to specific triggers** and occur in the absence of organic pathology. The normal physical exam rules out cardiac, pulmonary, or metabolic causes (e.g., hypoglycemia), supporting a diagnosis of **panic disorder**. The DSM-5 criteria emphasize the abrupt onset and the constellation of somatic and psychological symptoms.

**Why Each Wrong Option is Incorrect**
**Option A:** *Myocardial infarction* would present with chest pain, ECG changes, and elevated cardiac biomarkers, which are absent here.
**Option B:** *Hyperventilation syndrome* can mimic panic attacks but typically

✓ Correct Answer: A. Panic attack