A 48-year-old woman from Mumbai with a history of rheumatic fever presents with palpitations and dyspnea. On examination, she has an early diastolic decrescendo murmur at the left sternal border, a wide pulse pressure (systolic 160 mmHg, diastolic 50 mmHg), and a water-hammer pulse. Chest X-ray shows cardiomegaly with a prominent ascending aorta. Which investigation is most appropriate to assess the severity of aortic regurgitation and quantify the degree of left ventricular dilatation?

Explanation

## Investigation of Choice for Aortic Regurgitation Severity and LV Assessment ### Clinical Context The patient presents with classic features of severe aortic regurgitation (AR): early diastolic murmur, wide pulse pressure, water-hammer pulse, and signs of LV dilatation (cardiomegaly on CXR). The clinical presentation suggests hemodynamically significant AR. ### Why Transthoracic Echocardiography with Doppler is Correct **Key Point:** Transthoracic echocardiography with Doppler is the **first-line, non-invasive investigation** for assessing AR severity and quantifying LV dimensions and function. **High-Yield:** Doppler echocardiography provides: - **AR severity grading** using: - Jet width / LVOT diameter ratio - Pressure half-time (PHT) of AR jet - Regurgitant volume and regurgitant fraction - Holodiastolic flow reversal in the descending aorta (sign of severe AR) - **LV dimensions:** LV end-diastolic diameter (LVEDD), LV end-systolic diameter (LVESD) - **LV function:** LV ejection fraction (LVEF) - **Associated findings:** aortic root diameter, aortic valve morphology, other valvular lesions **Clinical Pearl:** Severity grading of aortic regurgitation: | Parameter | Mild | Moderate | Severe | |-----------|------|----------|--------| | Jet width / LVOT | <25% | 25–65% | >65% | | PHT (ms) | >500 | 200–500 | <200 | | Regurgitant volume (mL/beat) | <30 | 30–59 | ≥60 | | Regurgitant fraction (%) | <30 | 30–49 | ≥50 | | Holodiastolic flow reversal (descending aorta) | Absent | Absent | Present | **Key Point:** LV dilatation assessment is critical for management decisions: - LVEDD >55 mm or LVEF <50% → surgery indicated even if asymptomatic - LVEDD 50–55 mm → close follow-up with serial echocardiography **Mnemonic: SEVERE AR** — **S**ystolic flow reversal in descending aorta, **E**jection fraction decline, **V**olume regurgitant >60 mL, **E**nd-diastolic diameter >55 mm, **R**egurgitant fraction >50%, **E**arly closure of mitral valve. ### Why Transthoracic Echo is First-Line - Non-invasive, no radiation - High sensitivity and specificity (>90%) - Provides both structural and hemodynamic data - Guides timing of surgical intervention - Can be repeated serially for follow-up [cite:Harrison 21e Ch 282] --- ## Why Other Options Are Not Ideal **Cardiac MRI:** Excellent for detailed anatomical assessment and quantification of regurgitant volume, but it is not first-line. Reserved for cases where echocardiography is inconclusive, assessment of aortic root anatomy (e.g., in Marfan syndrome), or when precise LV volumes are needed for research. More time-consuming and costly. **Aortic root angiography:** Invasive and primarily used to visualize aortic root anatomy and assess coronary ostia before surgery. Not indicated for initial severity assessment of AR or LV function evaluation. **Radionuclide ventriculography:** Can assess LVEF and regurgitant fraction but provides limited anatomical detail, requires radiation, and is not first-line for valvular disease assessment. Largely replaced by echocardiography and cardiac MRI.