Jugular Venous Flow Events And Their Relationship To Jugular Venous Pulse Contours

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Next we shall consider the jugular venous flow events as related to the jugular venous pulse contours. Although the jugular venous column is in direct continuity with the right atrium, the venous system is innervated by the sympathetic system, which can influence the tone of the smooth muscles in their walls (19) and as such affect the level to which the column will rise for any given volume status ofthe individual and the corresponding right atrial pressure. With that background we shall consider the jugular flow events as they relate to the jugular venous pulse contour.

It is important to note that the descents or fall in pressure cause acceleration of venous inflow, as stated earlier. Although more volume of blood enters the heart during diastole, the flow is slower over a longer period oftime. In systole, however, the flow is much faster over a shorter period of time (first half of systole). The column of blood in the jugulars is in direct continuity with the blood in the right atrium and the right ventricle in diastole. During systole, the tricuspid valve is closed, and therefore the ventricle is excluded from this system. During the slow filling phase of diastole, the flow into the jugulars at the top of the system is matched to that entering the ventricle (Fig. 7). This represents the baseline state, at which time whatever pressure is developed is mainly determined by the ventricular distensibility (compliance) assuming that the blood volume status of the patient is normal (pre-a wave pressure) (Fig. 7A).

With the onset of right atrial contraction, the right atrium becomes smaller and, in fact, is emptying. Therefore, it is unable to accept any venous return. The flow in the superior vena cava and the jugulars decelerates and almost ceases. The continuous inflow from the periphery into the system will raise the volume and the pressure, thus causing the buildup ofthe normal a wave in the jugular (Fig. 7B). The level to which this may rise will depend on the degree of deceleration of forward flow. This, in fact, will depend on the strength ofthe right atrial contraction and the pressure generated by it. During atrial relaxation, the atrium expands causing its pressure to fall leading to flow acceleration in the jugulars.

Jugular Venous Pressure Ekg

Fig. 7. Simultaneous recordings of electrocardiogram (ECG), jugular venous pulse (JVP), and right atrial (RA) and right ventricular (RV) pressure tracings from a patient with normal right heart hemodynamics. Superimposed are diagrammatic representations of right atrium and right ventricle during various phases of the cardiac cycle. The arrows represent blood flow velocities and help explain the changes in the JVP contour relating them to right heart physiology. The thickness of the arrows relate to the velocity of flow. The columns extending upward from the heart represents the superior vena cava and the jugular complex. The arrows at the top of the columns represent steady flow from the periphery into the vena cava. Each section is shown separately in Fig. 7A—F. (Modified and reprinted from ref. 42. Copyright 2005 with permission from Excerpta Medica Inc.)

Right Ventricle Pulse Flow

Fig. 7. (A) In mid diastole (slow filling phase), the tricuspid valve is open and right ventricle (RV) and right atrium (RA) with superior vena cava (SVC) form a single chamber. The ventricle is almost full, having gone through the rapid filling phase. The slow dilatation of RV causes slow flow rate in SVC, which is matched by inflow from the periphery.

Fig. 7. (A) In mid diastole (slow filling phase), the tricuspid valve is open and right ventricle (RV) and right atrium (RA) with superior vena cava (SVC) form a single chamber. The ventricle is almost full, having gone through the rapid filling phase. The slow dilatation of RV causes slow flow rate in SVC, which is matched by inflow from the periphery.

a wave rise a wave rise

Jugular Venous Pulse

Fig. 7. (B) When the right atrium (RA) contracts, it is emptying and getting smaller and cannot accept any blood at that point in time. Flow into the heart in the superior vena cava (SVC) ceases. The blood coming into the system from the periphery causes a rise (a wave rise) in the jugular venous pulse.

Fig. 7. (B) When the right atrium (RA) contracts, it is emptying and getting smaller and cannot accept any blood at that point in time. Flow into the heart in the superior vena cava (SVC) ceases. The blood coming into the system from the periphery causes a rise (a wave rise) in the jugular venous pulse.

This is a passive flow across a pressure gradient between the higher jugular pressure and lower right atrial pressure. Since the flow velocity into the atrium at this time is faster than the continuous inflow from the periphery, the jugular contour falls, causing the x descent (Fig. 7C).

The next event to follow is ventricular systole. As explained previously, this causes an active sudden drop in right atrial pressure, almost like a suction effect. This accelerates the flow into the right atrium markedly. This also will lead to a further fall in the jugular contour (x' descent) (Fig. 7D). Although this corresponds to the right atrial x' descent, there is a transmission delay (40). The latter is accounted for by the time taken for the flow acceleration to develop in the superior vena cava and the jugulars.

During the latter half of systole, the descent of the base comes to a halt, thereby eliminating any further suction effect and/or drop in right atrial pressure. This will lead to a reduction in flow acceleration towards the heart. The venous inflow from the periphery will now exceed the flow into the right atrium, thereby filling the system. This will lead to a rise in jugular and atrial pressures, causing the v wave to build up (Fig. 7E). Assuming normal blood volume, the level to which this will rise in the jugulars will depend on three factors:

1. The baseline "pre-a wave pressure" in the system

2. The compliance or distensibility of the right atrium

3. The systemic venous tone, which is predominantly influenced by the state of the sympathetic tone x descent x descent

Fig. 7. (C) After atrial systole, the right atrium (RA) relaxes (x descent), thus increasing its capacity and allowing blood to flow in. This flow rate in the superior vena cava (SVC) is faster than the rate at which blood is flowing into the system from the periphery, therefore the jugular pulse is seen to fall.

Q x' descent

Q x' descent

Jugular Venous Pulse

Fig. 7. (D) In early systole as the right ventricle (RV) contracts, it gets smaller and pulls down the base. This causes almost a suction effect (x' descent) and blood rushes into the right atrium (RA). This rate of flow is much faster than the rate of peripheral inflow. This causes a sudden fall in the jugular pulse contour.

Fig. 7. (D) In early systole as the right ventricle (RV) contracts, it gets smaller and pulls down the base. This causes almost a suction effect (x' descent) and blood rushes into the right atrium (RA). This rate of flow is much faster than the rate of peripheral inflow. This causes a sudden fall in the jugular pulse contour.

Right Ventricle Pulse Flow

Fig. 7. (E) Most ejection out of the ventricle occurs during the first third of systole, and the maximum decrease in right ventricle (RV) dimension occurs during this phase. During the later part of systole, the RV size does not decrease much further. The pull on the base of the RV also is not significant at this time. By this time the RA also is full and therefore the flow in the superior vena cava (SVC) is very slow and certainly slower than blood coming from the periphery. This leads to a rise in the jugular column (v wave).

Fig. 7. (E) Most ejection out of the ventricle occurs during the first third of systole, and the maximum decrease in right ventricle (RV) dimension occurs during this phase. During the later part of systole, the RV size does not decrease much further. The pull on the base of the RV also is not significant at this time. By this time the RA also is full and therefore the flow in the superior vena cava (SVC) is very slow and certainly slower than blood coming from the periphery. This leads to a rise in the jugular column (v wave).

When the tricuspid valve opens with the onset of diastole, the ventricular pressure having fallen to zero allows flow through the development of a pressure gradient in the system. The acceleration of flow during this early phase of diastole is not as prominent as that which occurs during systole and therefore leads to a less prominent fall in pressure contour in the right atrium. In addition the right atrium, being a capacitance chamber, will get smaller in the process of emptying into the ventricle, and therefore the full flow velocity at the tricuspid valve is not reflected in the superior vena cava and the jugular system. This will result in the less prominent fall in the jugular contour (they descent) (Fig. 7F).

The normal a wave caused by the atrial contraction and the normal v wave caused by the venous filling of the atrium during later part of ventricular systole are associated with slow and small rises of pressure. They do not exceed generally 5 mmHg and are often closer to 2-3 mmHg. Such small and slow pressure buildup in the RA does not affect the jugular venous inflow velocity significantly except to cause deceleration. They do not ever cause reversal of forward flow.

Retrograde flow into the jugulars from the superior vena cava is always abnormal. No matter the mechanisms of origin, such reversal can always be shown to be associated with abnormal pressure rises in the atrium (40). This could happen during systole in the presence of normal A-V conduction because of tricuspid regurgitation if it is significant (40,49).

Physical Exam Jugular Venous Pressure

Fig. 7. (F) As the tricuspid valve opens in early diastole, blood flows passively across a pressure gradient into the right ventricle (RV) from the right atrium (RA). The pressure in the RA is the v wave pressure, and the pressure in the RV is close to zero because of active right ventricular relaxation. The flow at the tricuspid valve is, however, not fully reflected in the superior vena cava (SVC) because of the capacitance of the RA, which can shrink as it were in size as it empties into the RV. The flow in the SVC is only minimally faster than the flow coming from the periphery. The difference of the two being small, the y descent is not very prominent in the jugulars.

Fig. 7. (F) As the tricuspid valve opens in early diastole, blood flows passively across a pressure gradient into the right ventricle (RV) from the right atrium (RA). The pressure in the RA is the v wave pressure, and the pressure in the RV is close to zero because of active right ventricular relaxation. The flow at the tricuspid valve is, however, not fully reflected in the superior vena cava (SVC) because of the capacitance of the RA, which can shrink as it were in size as it empties into the RV. The flow in the SVC is only minimally faster than the flow coming from the periphery. The difference of the two being small, the y descent is not very prominent in the jugulars.

It can then eliminate the x' descent and cause an early abnormal v wave pressure rise in the atrium (Fig. 7G).

When atrial and ventricular contraction are dissociated as in certain abnormal heart rhythms (e.g., complete A-V block with a ventricular rhythm independent and often slower than the blocked atrial complexes of sinus node origin), simultaneous atrial and ventricular contraction could occur, resulting in abnormal pressure waves termed the "cannon" waves. The atrial contraction occurs against a closed tricuspid valve, leading to sudden development of high atrial pressure. During the cannon waves, the high atrial pressure is associated with reversal of flow in the jugulars in systole (40). The reversed flow into the jugulars added to the normal inflow from the periphery cause increased filling of the jugular-superior vena caval system, resulting in the abnormally prominent waves (Fig. 7H).

Flow reversal can also occur in diastole. Very powerful atrial contractions may occasionally result in high a wave pressure in the RA (often in the range of15 mmHg or more), which could also be shown to be associated with reversal of forward flow during the end-diastolic phase (40). This could happen in tricuspid stenosis, which is a rare condition,

Measure The Pulse The Neck

Fig. 7. (G) Simultaneous recordings of electrocardiogram (ECG), phonocardiogram (Phono), jugular venous pulse (JVP), and the jugular venous flow velocity (JVF) from a patient with tricuspid regurgitation. It shows the systolic retrograde flow (Ret Sf) from the right ventricle (RV) into the right atrium (RA). This reverses the flow in superior vena cava (SVC), giving rise to a prominent rise in jugular pulse contour ("cv" wave). The Ret Sf abolishes the effect of the descent of the base during RV contraction. In addition, the retrograde flow into the RA because of RV contraction raises the v wave pressure to higher levels. During the early filling phase of diastole when the RV pressure falls to zero, there is a higher gradient of pressures between the RA and the RV, which makes the fall steep (prominent y descent).

Fig. 7. (G) Simultaneous recordings of electrocardiogram (ECG), phonocardiogram (Phono), jugular venous pulse (JVP), and the jugular venous flow velocity (JVF) from a patient with tricuspid regurgitation. It shows the systolic retrograde flow (Ret Sf) from the right ventricle (RV) into the right atrium (RA). This reverses the flow in superior vena cava (SVC), giving rise to a prominent rise in jugular pulse contour ("cv" wave). The Ret Sf abolishes the effect of the descent of the base during RV contraction. In addition, the retrograde flow into the RA because of RV contraction raises the v wave pressure to higher levels. During the early filling phase of diastole when the RV pressure falls to zero, there is a higher gradient of pressures between the RA and the RV, which makes the fall steep (prominent y descent).

Jvp Physical Exam

Fig. 7. (H) Simultaneous recordings of electrocardiogram (ECG), jugular venous pulse (JVP), and jugular venous flow velocities (JVF) from a patient with a permanent pacemaker. It shows a regular ventricular rhythm caused by ventricular pacing with independent P waves with atrioventricular dissociation. Arrows on ECG point to P waves. The bigger arrows on JVF indicate atrial relaxation flows corresponding to x descents. In the first beat, P and QRS are synchronous, giving rise to retrograde flow into SVC and causing a cannon wave. Note that the duration of the cannon wave is shorter than the duration of the v wave of tricuspid regurgitation shown in Fig. 7G. Because of the varying P and QRS relationship, the x, x', and y descents change from beat to beat. In the second beat the P and QRS relationship is basically normal with a normal PR interval, and the x, x', and y descents are normal. In the last beat the PR is long and the x descent is well separated from the x' descent.

Jugular Venous Pulse

Fig.8. Jugular venous pulse (JVP) from a patient with well-compensated severe pulmonary hypertension with right ventricular (RV) hypertrophy and decreased compliance. The RV systolic pressure is between 90 and 100 mmHg. Note the prominent a wave on the JVP. The a wave rise is almost as fast as the descent. The overlying diagrams depict the events at different phases of the cardiac cycle. The first diagram shows the retrograde flow into the SVC during atrial contraction. The x - x' descent combination is still the most prominent descent. (Modified and reprinted from ref. 41. Copyright 2005 with permission from Excerpta Medica Inc.)

Fig.8. Jugular venous pulse (JVP) from a patient with well-compensated severe pulmonary hypertension with right ventricular (RV) hypertrophy and decreased compliance. The RV systolic pressure is between 90 and 100 mmHg. Note the prominent a wave on the JVP. The a wave rise is almost as fast as the descent. The overlying diagrams depict the events at different phases of the cardiac cycle. The first diagram shows the retrograde flow into the SVC during atrial contraction. The x - x' descent combination is still the most prominent descent. (Modified and reprinted from ref. 41. Copyright 2005 with permission from Excerpta Medica Inc.)

and in patients with severe decrease in RV compliance. In the latter patients, the RV is unable to dilate completely to accept blood from the contracting right atrium and the blood has no choice but to flow back into the venae cavae (Fig.8).

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