Diagnosis of Sudden Dyspnoea with ECG and V/Q Scan Findings

The patient presents with sudden dyspnoea, a critical symptom often associated with acute cardiopulmonary events. Key findings guide the diagnosis:

• Patient Profile: A 60-year-old hypertensive male with a recent history of stroke (2 weeks prior). This history suggests potential immobility, a risk factor for deep vein thrombosis (DVT).
• Symptom: Sudden onset of dyspnoea points towards an acute event rather than a slowly progressing condition.
• ECG Findings: The presence of the \(S_{1}Q_{3}T_{3}\)$ pattern on the ECG is highly suggestive of acute right ventricular strain. This pattern typically indicates increased pressure or volume overload in the right heart.
• V/Q Scan Findings: Major areas of reduced perfusion on the ventilation/perfusion (V/Q) scan directly indicate blocked blood flow to lung segments, characteristic of pulmonary embolism.

Evaluating Probable Diagnoses

Considering the clinical picture and investigation results:

• Pulmonary Thromboembolism (PTE): This diagnosis aligns perfectly. Sudden dyspnoea is a classic symptom. The risk factors (immobility post-stroke, hypertension) predispose the patient to DVT, which can lead to PTE. The \(S_{1}Q_{3}T_{3}\)$ pattern reflects the right heart strain caused by the embolism obstructing pulmonary arteries. The V/Q scan finding of reduced perfusion is a hallmark of PTE.
• Pneumothorax: While causing sudden dyspnoea, pneumothorax typically presents with diminished breath sounds on the affected side and may show mediastinal shift. V/Q scan findings would likely show absent perfusion in the collapsed area. The specific ECG pattern is less common.
• Congestive Cardiac Failure (CCF): CCF usually presents with gradual onset dyspnoea, orthopnoea, and peripheral oedema. While hypertension is a risk factor, the sudden onset and specific ECG/V/Q findings are less typical for CCF compared to PTE.
• Psychogenic Dysfunction: This is a diagnosis of exclusion and unlikely given the objective ECG and V/Q scan findings indicating a significant physiological abnormality.

Therefore, the combination of sudden dyspnoea, history suggestive of DVT risk, the specific \(S_{1}Q_{3}T_{3}\)$ ECG pattern, and reduced perfusion on V/Q scan strongly indicates Pulmonary Thromboembolism.