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Page 1: Introduction to Diastology

  • Diastolic Function

    • Diastole consists of four phases:

      • Isovolumic Relaxation Time (IVRT)

      • Rapid Filling

      • Diastasis

      • Atrial Contraction

    • Divided into two main parts: "passive" and "active" filling.

  • Phases of Diastole

    • Rapid Filling:

      • Occurs when ventricular pressure drops below atrial pressure.

      • Results from the relaxation (expansion) of myocardium.

      • Ventricles pull blood in through AV valves, termed passive filling.

    • Atrial Contraction:

      • Atria contract to push blood into ventricles, termed active filling.

  • Impaired Relaxation

    • Refers to difficulties in the myocardium's ability to relax and expand properly.

    • Leads to impaired early relaxation, the first type of diastolic dysfunction.

Page 2: Restricted Filling and Assessment

  • Restrictive Filling

    • Second phase (Atrial Contraction) depends on the ventricles' compliance.

    • Compliance: the ventricles' ability to stretch to accommodate blood.

    • Loss of compliance leading to restricted filling is termed restrictive filling, the second type of diastolic dysfunction.

    • Commonly, impaired early relaxation progresses to pseudonormal then to restrictive filling.

  • Assessment of Diastolic Function

    • Eight different measurements to assess diastolic function, including Doppler measurements.

    • Focus is primarily on left heart diastolic function.

Page 3: Measurements for Diastolic Function

  • 1. Mitral Inflow: E/A Ratio

    • Use pulsed-wave Doppler on mitral valve during diastole with Apical 4-Chamber view.

    • E-wave (first peak, larger) and A-wave (second peak, smaller) measured.

    • E/A ratio is calculated by dividing E peak velocity by A peak velocity.

      • Normal range: 0.8 - 1.5.

      • In older patients (>65 years), E wave typically smaller than A wave but ratio should not drop below 0.75.

  • 2. Mitral Inflow: Deceleration Time (DT)

    • Measure the time from peak E wave to baseline.

    • Normal DT should be between 140 - 220 ms.

    • Values outside of this range could indicate diastolic dysfunction.

Page 4: Pulmonary Vein Measurements

  • 3. Pulmonary Vein: AR Velocity

    • Use pulsed-wave Doppler on the pulmonary vein.

    • Triphasic waveform: S, D (early diastole), and AR (atrial reversal).

    • Normally, S > D and AR peak velocity should be < 35 cm/s.

  • 4. Pulmonary Vein: AR Duration

    • Measure duration of AR wave compared to mitral A wave.

    • AR duration should not exceed mitral A wave duration by more than 30 ms.

Page 5: Tissue Doppler and IVRT

  • 5. Tissue Doppler: E/e' Ratio

    • Assess motion at inferior septal and antero-lateral walls of the left ventricle using tissue Doppler.

    • Measure wall motion related to E peak from mitral inflow.

    • e' normal velocity should be > 10 cm/s and not more than 8 times smaller than the E wave.

  • 6. IVRT Duration

    • IVRT marks the time with all valves closed at the beginning of diastole.

    • Measure between peaks of aortic and mitral valve flows.

    • Normal duration is 70 - 100 ms; deviations indicate dysfunction.

Page 6: Left Atrial Volume Measurement

  • 7. Left Atrial Volume

    • Measure LA volume at end systole using the biplane Simpson method.

    • Normal range is 18 - 58 mL with indexed volume of 16 - 28 mL/m².

    • Focus on dilation as an indicator of diastolic dysfunction, particularly restrictive filling.

Page 7: Color M-Mode Method

  • 8. Color M-Mode: Inflow Velocity Propagation Slope (CMM-Vp)

    • Perform this analysis using an Apical 4-Chamber view and color M-mode displayed simultaneously.

    • Look at flow jets and their slope for diastolic function assessment.

    • Normal propagation slope should be > 45 cm/s; a slope < 45 cm/s indicates diastolic dysfunction.

Introduction to Diastology

Diastolic function refers to the phase of the cardiac cycle when the heart chambers fill with blood. Diastole consists of four key phases: Isovolumic Relaxation Time (IVRT), Rapid Filling, Diastasis, and Atrial Contraction. This process is divided into two main parts: "passive" and "active" filling. Rapid filling occurs when ventricular pressure drops below atrial pressure, resulting from the relaxation and expansion of the myocardium, allowing the ventricles to pull blood in through the atrioventricular (AV) valves. This phase is termed passive filling. Following this, the atria contract to push blood into the ventricles, known as active filling.

Impaired relaxation in the myocardium can lead to difficulties in proper relaxation and expansion, manifesting as impaired early relaxation, the first type of diastolic dysfunction. Restrictive filling, the second type of dysfunction, arises during atrial contraction when the ventricles can no longer stretch adequately to accommodate blood—a phenomenon referred to as compliance. Commonly, the progression of impaired early relaxation leads to a pseudonormal pattern and finally to restrictive filling.

Assessment of diastolic function is performed through eight different measurements, focusing primarily on left heart diastolic function. Key measurements include the Mitral Inflow E/A Ratio obtained using pulsed-wave Doppler on the mitral valve in the apical 4-chamber view. The E-wave is the first peak and is typically larger than the A-wave, and the E/A ratio is calculated by dividing the E peak velocity by the A peak velocity, with a normal range between 0.8 and 1.5. In older patients above 65 years, the E wave is usually smaller than the A wave, but the ratio should not drop below 0.75.

The Mitral Inflow Deceleration Time (DT) is measured from the peak E wave to baseline, with a normal range between 140 and 220 ms; values beyond this range may indicate diastolic dysfunction. Pulmonary vein measurements are also crucial; for instance, the AR Velocity is assessed with pulsed-wave Doppler, where a normal triphasic waveform shows that S is greater than D, and AR peak velocity should be less than 35 cm/s. Moreover, the duration of the AR wave should not exceed that of the mitral A wave by more than 30 ms.

The Tissue Doppler E/e' Ratio is assessed by observing motion in the inferior septal and antero-lateral walls of the left ventricle, with normal e' velocities exceeding 10 cm/s and not being more than eight times smaller than the E wave. Additionally, IVRT duration is measured between the peaks of aortic and mitral valve flows, with normal values ranging from 70 to 100 ms, deviations indicating dysfunction.

Left atrial volume, measured at end systole using the biplane Simpson method, also plays a critical role; the normal range is between 18 and 58 mL, and the indexed volume is 16 to 28 mL/m², where dilation is indicative of diastolic dysfunction, particularly restrictive filling. Finally, the Color M-Mode method assesses the Inflow Velocity Propagation Slope (CMM-Vp) using the Apical 4-Chamber view, where a normal slope should be more than 45 cm/s and a slope less than 45 cm/s indicates diastolic dysfunction.