Prea wave Pressure

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This is the pressure in diastole during the slow filling phase when the RV and the RA pressures become equal. During this phase the atrium and the right ventricle are one chamber on account of the open tricuspid valve. The level at which this equalization is achieved is determined by the compliance of the RV and the surrounding pericardium (Fig 7A).

The RV compliance implies the distensibility of the endocardium, myocardium, as well as epicardium. It can become abnormal and less distensible whenever pathological

Fig.9. Normal Jugular Venous Pulse (JVP), showing a dominant fall during systole due to the x and the x' descents. The c wave in the JVP is usually a carotid pulse artefact unlike the c wave noted on the RA pressure tracing.

processes develop in any portion of the RV wall. These processes could be in the form of hypertrophy (thickening of the myocardial fibres) such as those caused secondary to excessive pressure load (e.g., pulmonary hypertension or pulmonary stenosis). It could be in the form of inflammatory process such as myocarditis, of an infiltrative nature as in amyloidosis, ischemia, and infarction (RV infarction is usually rare but could occur when the right coronary artery becomes occluded quite proximally before the RV branch origin; this is usually associated with an infero-posterior wall LV infarction), or fibrosis, which may supervene in the course of any of the pathological processes. This diastolic dysfunction can coexist with or without a systolic dysfunction (Figs. 10 and 11).

If the RV has in fact developed systolic dysfunction and failure, this will further aggravate the diastolic dysfunction, which often precedes systolic dysfunction. If the systolic emptying is poor, the ventricular volume will be higher at the end of systole and therefore its pressure will rise quickly to high levels with diastolic inflow.

If the RV wall is surrounded by a thick and fibrotic or calcific pericardium (e.g., chronic constrictive pericarditis) or a pericardial sac filled with fluid under some pressure (e.g., acute or subacute pericarditis with pericardial effusion), easy diastolic expansion of the ventricle will not be possible, leading to a higherpre-a wave pressure for any degree of filling.

The pre-a wave pressure sets the baseline for the a wave and v wave pressures (47). If it becomes elevated, as under the conditions listed above, one would expect higher a wave and v wave pressures in the atrial pressure pulse.

Elevated pre-a wave pressure would be reflected in the jugulars as an elevated jugular venous pressure as judged by the assessment of the level of the top of the jugular pulsations in relation to the sternal angle (see JVP Videofiles 2-4 in Jugular Venous Pulse on the Companion CD).

RV Infarction

RV Infarction

Fig.10. Simultaneous recordings of RA and RV pressures in mmHg. from a patient with Right Ventricular (RV) infarction, along with Jugular Venous Pulse (JVP). Note the double descents x' = y pattern in both the JVP and the RA pressure curve. Arrow points to the pre a wave pressure (Reproduced with kind permission from ref. 47.)

Fig.10. Simultaneous recordings of RA and RV pressures in mmHg. from a patient with Right Ventricular (RV) infarction, along with Jugular Venous Pulse (JVP). Note the double descents x' = y pattern in both the JVP and the RA pressure curve. Arrow points to the pre a wave pressure (Reproduced with kind permission from ref. 47.)

Fig. 11. Simultaneous recordings of jugular venous flow (JVF) velocity and right ventricular (RV) and right atrial (RA) pressures from a patient with RV infarction. Note the prolonged PR interval on electrocardiogram (ECG). Because of RV infarction, the RV contractility is poor and the x' descent is also poor. The x descent is well separated from the X descent because of the long PR. Note the atrial relaxation flow on JVF corresponding to x descent. The y descent is dominant and so is the corresponding Df in JVF. Small arrow indicates pre-a wave pressure. (Reproduced with kind permission from ref. 47.)

Fig. 11. Simultaneous recordings of jugular venous flow (JVF) velocity and right ventricular (RV) and right atrial (RA) pressures from a patient with RV infarction. Note the prolonged PR interval on electrocardiogram (ECG). Because of RV infarction, the RV contractility is poor and the x' descent is also poor. The x descent is well separated from the X descent because of the long PR. Note the atrial relaxation flow on JVF corresponding to x descent. The y descent is dominant and so is the corresponding Df in JVF. Small arrow indicates pre-a wave pressure. (Reproduced with kind permission from ref. 47.)

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