The major elements of the cardiac exam include observation, palpation and, most importantly, auscultation (percussion is omitted). As with all other areas of the physical exam, establishing adequate exposure and a quiet environment are critical. Initially, the patient should rest supine with the upper body elevated 30 to 45 degrees. Most exam tables have an adjustable top. If not, use 2 or 3 pillows. Remember that although assessment of pulse and blood pressure are discussed in the vital signs section they are actually important elements of the cardiac exam.
The evaluation of the cardiovascular system focuses on the heart, but should also include an assessment for disease in the arterial system throughout the body. Atherosclerosis, the most common cardiovascular ailment in the western world, is a systemic disease. As such, appropriate evaluation requires a broad assessment.
Assessment for distention of the right Internal Jugular vein (IJ) is a difficult skill. Its importance lies in the fact that the IJ is in straight-line communication with the right atrium. The IJ can therefore function as a manometer, with distention indicating elevation of Central Venous Pressure (CVP). This in turn is an important marker of intravascular volume status and related cardiac function. The focus here is on simply determining whether or not Jugular Venous Distention (JVD) is present. A discussion of the a, c and v waves that make up the jugular venous pulsations can be found elsewhere. These are quite difficult to detect for even the most seasoned physician.
Why is JVD so hard to assess The IJ lies deep to skin and soft tissues, which can provide quite a bit of cover. Additionally, this blood vessel is under much lower pressure then the adjacent, pulsating carotid artery. It therefore takes a sharp eye to identify the relatively weak, transmitted venous impulses.
A few things to remember:
- Think anatomically. The right IJ runs between the two heads (sternal and clavicular) of the sternocleidomastoid muscle (SCM) and up in front of the ear. This muscle can be identified by asking the patient to turn their head to the left and into your hand while you provide resistance to the movement. The two heads form the sides of a small triangle, with the clavicle making up the bottom edge. You should be able to feel a shallow defect formed by the borders of these landmarks. Note, you are trying to identify impulses originating from the IJ and transmitted to the overlying skin in this area. You can't actually see the IJ. The External Jugular (EJ) runs in an oblique direction across the sternocleidomastoid and, in contrast to the IJ, can usually be directly visualized. If the EJ is not readily apparent, have the patient look to the left and valsalva. This usually makes it quite obvious. EJ distention is not always a reliable indicator of elevated CVP as valves, designed to prevent the retrograde flow of blood, can exist within this vessel causing it to appear engorged even when CVP is normal. It also makes several turns prior to connecting with the central venous system and is thus not in a direct line with the right atrium.
- Take your time. Look at the area in question for several minutes while the patient's head is turned to the left. The carotid artery is adjacent to the IJ, lying just medial to it. If you are unsure whether a pulsation is caused by the carotid or the IJ, place your hand on the patient's radial artery and use this as a reference. The carotid impulse coincides with the palpated radial artery pulsation and is characterized by a single upstroke timed with systole. The venous impulse (at least when the patient is in sinus rhythm and there is no tricuspid regurgitation) has three components, each associated with the aforementioned a, c and v waves. When these are transmitted to the skin, they create a series of flickers that are visible diffusely within the overlying skin. In contrast, the carotid causes a single up and down pulsation. Furthermore, the carotid is palpable. The IJ is not and can, in fact, be obliterated by applying pressure in the area where it emerges above the clavicle.
- Search along the entire projected course of the IJ as the top of the pressure wave (which is the point that you are trying to identify) may be higher then where you are looking. In fact, if the patient's CVP is markedly elevated, you may not be able to identify the top of the wave unless they are positioned with their trunk elevated at 45 degrees or more (else their will be no identifiable "top" of the column as the entire IJ will be engorged). After you've found the top of the wave, see what effect sitting straight up and lying down flat have on the height of the column. Sitting should cause it to appear at a lower point in the neck, while lying has the opposite effect. Realize that these maneuvers do not change the actual value of the central venous pressure. They simply alter the position of the top of the pulsations in relation to other structures in the neck and chest.
- Shine a pen light tangentially across the neck. This sometimes helps to accentuate the pulsations.
- If you are still uncertain, apply gentle pressure to the right upper quadrant of the abdomen for 5 to 10 seconds. This elicits Hepato-Jugular Reflux which, in pathologic states, will cause blood that has pooled in the liver to flow in a retrograde fashion and fill out the IJ, making the transmitted pulsations more apparent. Make sure that you are looking in the right area when you push as the best time to detect any change in the height of this column of blood is immediately after you apply hepatic pressure.
- Once you identify JVD, try to estimate how high in cm the top of the column is above the Angle of Louis. The angle is the site of the joint which connects the manubrium with the rest of the sternum. First identify the supra-sternal notch, a concavity at the top of the manubrium. Then walk your fingers downward until you detect a subtle change in the angle of the bone, which is approximately 4 to 5 cm below the notch. This is roughly at the level of the 2nd intercostal space. The vertical distance from the top of the column to this angle is added to 5cm, the rough vertical distance from the angle to the right atrium with the patient lying at a 45 degree angle. The sum is an estimate of the CVP. However, if you can simply determine with some accuracy whether JVD is present or not, you will be way ahead of he game! Normal is 7-9 cm.