Evaluation of JVP

Transcript of the video: Now we will discuss the basic principles of evaluation of jugular venous pressure and jugular venous pulse. These are assessed in the internal jugular vein and not in the external jugular vein. To revise the anatomy lessons, this is the external jugular vein and this is the internal jugular vein. Now, why we should not be looking at external jugual vein, though it is much easier to find out is that, in lower portion, it may be kinked so that it may not reflect the true right atrial pressure. The whole purpose of assessing the jugular venous pressure and pulse is that it reflects the right atrial pressure and hence the filling pressure of the right ventricle. So, if this is obstructed lower down, then there is no point in assessing it. So you have to look carefully at the pulsations of the internal jugular vein which you will be able to find out with some experience. And you know that the pulsations are laterally and view from a side will be better, to assess the wave form of the jugular venous pulse. So that is the importance of assessing internal jugular vein.

Jugular venous pressure can be assessed in the sitting position if the venous column is easily visible in the root of the neck. But, if it is not visible, you have to keep the person in the slanting position, usually at 45 degrees.  And, the vertical level above the sternal angle is measured. That is the vertical height of the venous column above the sternal angle. Sternal angle is usually about 5 centimeters above the mid right atrial region. Right atrial pressures are measured from the mid sternal (error: mid thoracic) level, that is in the cathlab, you measure the distance between anterior and posterior chest wall, and keep the transducer at the level of the mid thoracic level. And that will be the approximate level of the tricuspid valve, the reference point for measuring right atrial pressure. The pressure from there, to the sternal angle, the difference will be 5 centimeters of water. So, if you measure from sternal angle, suppose the jugular venous pressure is 5 cm, then the right atrial pressure will be 10 centimeters of water. And that will be approximately 10 mm of mercury, though it is not exact. And, after measuring the jugular venous pressure, you will also look at the pulsations of the jugular vein. The pulsations are better seen laterally and you may have to shine a light from the side of the neck to see the venous pulsations very well.

You can also check the rise in jugular venous pressure by giving compression in the upper abdomen, in the right upper quadrant and the increase in jugular venous pressure by abdominal compression is known as abdomino-jugular reflux, also called hepatojugular reflux, because an enlarged liver in this region will get compressed by compressing the upper abdomen. But actually it is the increased intra-abdominal pressure, which is transmitted to the inferior vena cava and from there into the right atrium and into the jugular venous column. Usually in a normal person if you give compression, the slight rise will occur and it will come down on sustained compression because heart will take care of the extra load. But a failing right heart will not be able to take care of the extra load and there will be a sustained elevation. This is abdominojugular reflux or hepatojugular reflux, sometimes used when when you have a borderline case. But while compressing here in a patient with heart failure, it can elicit pain because there could be tender hepatomegaly in patients with heart failure.

Another important aspect is to look at the respiratory variation in jugular venous pressure and pulsations. In inspiration, normally jugular venous pressure decreases, but amplitude of pulsation increases. If there is an inspiratory increase in jugular venous pressure, it is known as a positive Kussmaul sign, increase in inspiratory jugular venous pressure. That occurs in right heart failure and constrictive pericarditis. Constrictive pericarditis is an important cause for Kussmaul sign or inspiratory increase in jugular venous pressure. Then, these are the important waves to be looked at in the jugular venous pulsation. The first positive wave is the A wave, and on inspection we will see only A and V waves. You will not see the C wave. C wave in jugular venous pulsation is due to carotid artefact, due to the pulsation of the carotid artery beneath it. In right atrial tracing, this occurs at the time of right ventricular contraction, with bulging upwards of the tricuspid valve. But these are not seen, C waves are not seen in jugular venous pulse when you examine visually, only in tracings. And the descent after the A wave, A wave occurs due to atrial contraction, V wave is due to ventricular filling, so the descent after the A wave is known as the X descent. And if there is a C wave, the descent after the X is known as X prime descent. And the descent after the V wave is the Y wave, sorry, Y descent. X descent, X prime descent and Y descent. The X prime descent is absent in tricuspid regurgitation in which, C and V waves fuse together. The Y descent is shallow in tricuspid stenosis, and absent in cardiac tamponade. On the other hand, the Y descent is very prominent in constrictive pericarditis, and it is known as Friedreich’s sign. An often asked question is, how will you differentiate between venous pulsation and arterial pulsation. So the answer is areterial pulsations are better felt than seen, while venous pulsations are better seen than felt. Then, venous pulsation has a definite upper level. Arterial pulsation has only one wave during systole usually. But venous pulsation has multiple waves, as you can see, at least two waves are seen during each cardiac cycle. Then occasionally, when the venous pressure is very high, you may not be able to see the upper level. If it is very high, then it will go up to the ear lobe. So if you see laterally, you see the internal jugular pulsations. Sometimes you may be seeing the pulsation of the ear lobe. And, always better to put the patient in standing position if jugular venous pressure is high to see the upper level. But in a very sick patient, this is not possible.

Sometimes, the jugulars may be engorged, but non pulsatile. So it is important to check pulsatility along with the engorgement. So this is a schematic represention of superior vena caval obstruction, which causes enlarged, non pulsatile jugulars. Obstruction could be due to tumour or even a thrombus. Thrombus can sometimes occur when there is a central venous catheter or a multiple pacemaker or defibrillator leads there that can cause thrombus formation. Any hypercoagulable state also, there is a possibility of thrombus formation in the superior vena cava. But more common is mediastinal masses causing compression and obstruction to the superior vena cava, causing superior vena cava syndrome, with dilated, non pulsatile neck veins.

We noted that prominent V waves or CV waves can occur in tricupsid regurgitation. A prominent A wave can occur when the atrium is hypertrophied. Right atrial hypertrophy as in tricuspid stenosis, pulmonary stenosis and pulmonary hypertension. But in a VSD with pulmonary hypertension A wave is not prominent. So a prominent A wave in a complex congenital heart disease situation would indicate that interventricular septum is intact. It will not occur in the presence of a large VSD which equalizes both right ventricular and left ventricular pressures. And, if the P waves occur during ventricular systole, as in complete heart block, it can produce cannon waves. This is between the peak of R and end of T, is the electrical systole of the ventricle. So, if a P wave occurs in this segment, there will be atrial contraction against a closed tricuspid valve, producing cannon waves, very prominent waves, jugular venous pulses will be very prominent and in this situation also, because both these are occurring during systole. That is known as cannon waves. But, please remember that even though the classical situation for a cannon wave is complete heart block, the most common cause of a cannon wave is not complete heart block, rather, it is due to ventricular ectopy. Suppose a ventricular ectopy occurs in this region, so that P wave and ventricular systole are simultaneous, then it will cause cannon waves. Ventricular ectopics being much more common than complete heart block in the general population, you are more likely to see cannon waves due to ventricular ectopics than complete heart block. Both these are irregular cannon waves. It will not occur for every cardiac cycle. This cardiac cycle there will be no cannon wave, because P is before the QRS complex. These two there will be. In this case also, most probably it will not be there, because P wave occurred almost at the end of T wave. So by the time after the electromechanical delay, when the atrium contracts, ventricle will be in diastole. There are situations in which there can be regular cannon waves. One is ventricular tachycardia with regular retrograde activation. Second is junctional tachycarida. Then sometimes, prolonged first degree AV block. Suppose this is a little more prolonge, this P will come here. That can also cause regular cannon waves. Especially, in patients with rheumatic fever, PR interval is prolonged and there is sinus tachycardia. So, instead of QRS being here, it will be here and the P wave will be here. So, rheumatic fever is one situation where you may see regular cannon waves because, first degree AV block in the presence of sinus tachycardia, P encroaches on to the previous systole.