CARDIOVASCULAR ASSESSMENT CONTINUED
Discussion of Heart Sounds
The loudness and intensity of heart sounds are important when you are listening. S1 and S2 are heard at different levels of loudness, depending upon where you listen on the chest. The loudness of S1 is mainly determined by the position of the heart valves when ventricles contract. If valve leaflets are wide open at the time of contraction, the sound is very loud. The loudness of the sound is also affected by the pressure of the blood. It is this pressure that “slams” the valves shut and generates the sound. If you recall that the interval between S1 and S2 corresponds to the systolic phase, then a murmur that is heard between S1 and S2 would be called a systolic murmur. Then a diastolic murmur would be called a murmur heard between S2 and S1, which corresponds to the diastolic phase of the cardiac cycle.
Next, these two murmurs, systolic and diastolic, can further be pinpointed by describing exactly when in the phase it occurs.
The murmur can be described as:
| early systolic | midsystolic | late systolic |
| early diastolic | middiastolic | late diastolic |
These above terms describe murmurs in the exact position that they fall in the phase. For example, an early systolic murmur would be “timed” as occurring early in the phase of systole; and so on for all the phases. Another term called holosystolic (also pansystolic), is used to for a murmur heard throughout the entire systolic phase (S1 to S2). Holodiastolic will be used to refer to the murmur heard throughout the entire diastolic phase (S2 to S1).
The timing of the murmur above is very difficult to assess in some patients. In other patients, the timing will be very easy to assess. An important factor is that the nurse have experience in listening to a variety of “normal” variations of normal heart sounds. It is this author’s opinion that most nurses with little experience listening to what a normal heart sounds like, will not have much success in determining the timing of heart murmurs. You must first listen to many different normal heart sounds. Once you have some experience at differentiating normal S1 and S2 sounds, then you will be able to identify abnormal sounds, and to determine the timing of those abnormal sounds. The valves are at their widest when blood is actually filling into the ventricle. As the ventricle fills and the atria empty, the leaflets of the valve begin to close or to narrow. At that point, when the atria are empty, the ventricle is contracting and slams the valve shut. This is the dynamic force behind the loudness and intensity of the heart sounds.
Other factors affect closure. Exercise, fever, anemia and other factors can affect heart rate and the force of the closure of the valves. Loudness, of course, is also affected.
Note the following changes due to disease:
- Mitral Stenosis - loud S1 and delayed closing of valve
- Heart Block - varying intensity of S1 and S2 due to incomplete emptying of the atria, leaflets and may be partially open at some times, completely open at others
- Atrial flutter; fibrillation - sounds vary in intensity for the same reason as above
- Bundle Branch Block – S1 may be widely split (two separate sounds make up S1) S2 can also be affected
- Normal Respirations – physiological splitting of S2 during late part of inspiration
- Pulmonic Stenosis – delayed emptying of right side—can cause splitting of S2
- Atrial-Septal Defect – causes delayed emptying of right side of heart, as in above condition, splitting of S2 will occur
- Hypertension – increases back pressure on aortic valve, causes increase in loudness of S2
These are some disease conditions and the resulting change in the heart sounds. The term murmur refers generally to any “extra” or unusual heart sound. Most nurses will not be expected to fully “diagnose” all murmurs and/or abnormal heart sounds. However, the nurse should be able to recognize whether or not the two normal sounds are present, and if they are not, what sounds that are present, should be described carefully.
When charting heart sounds for your nurse’s notes, chart only the sounds that are abnormal. Chart basic information such as heart rate, rhythm, intensity and abnormal sounds. Describe carefully their location in the cycle. Describe any coincidental factors that may be influencing the rhythm such as respirations or movement of the patient. For murmurs, chart where it occurs in the cardiac cycle, loudness, pitch, the location of where it is heard the best and other locations where it can be heard.
Also record the general type of sound heard and if anything makes the sound change in any way. For example, if you reposition the patient, does the sound change. If the patient happened to breathe deeply and the sound changed; all these would be notable events.
Following is a guide to auscultation of sounds of the heart. It is only a guide, and should be used with existing guidelines at your facility. The methods of charting are different at each hospital, so are responsibility levels for each type of nurse. Always use terms which are acceptable at your facility. If a heart sound or murmur is accompanied by adverse clinical symptoms, results should be reported.
GUIDE TO AUSCULTATION OF HEART SOUNDS
Step I Prepare patient
Have patient relax, remove cloths from waste up, cover with gown and provide for privacy
Step II Vital Signs
Record vital signs, TPR and Blood Pressure, note any abnormalities
Step III Heart Rate
Listen to apical pulse and record the rate, even though you already took the radial pulse rate from the above step; note any abnormal sounds while listening to apex
Step IV Rhythm
Determine the regularity of rhythm; regular or irregular?
- Is the irregularity due to respirations
- Auscultate at the points mentioned on previous page (6 points)
- Listen especially for any murmurs you previously heard
- Timing – describe where the sound is heard in the cardiac cycle
Step V Sounds
Describe carefully the sound heard that is abnormal. Is it a “rubbing sound” or a “clicking sound” or “swooshing” or other? Chart the sound just as you heard it. This course is not designed to make you a cardiologist, but the nurse should be able to recognize and chart anything abnormal in the cardiac cycle
Loudness of heart murmurs:
Once you have determined the timing and other gross characteristics of the murmur, you should determine and record the loudness. Loudness is graded on a numerical scale as shown below. Grade I is the softest and Grade VI is the loudest. *Remember, however, that you will see other scales used to measure loudness. Some authorities use a scale of I, II, III, IV. Some others use a scale of only I, II, III; so be aware of the scale that is generally used at your facility and apply the same principles to it.
Grade I Soft
Grade II Medium Soft
Grade III Loud **All of these ratings are very subjective
Grade IV Medium Loud
Grade V Louder
Grade VI Loudest
| Intensity of heart murmurs: | |
| Crescendo | begins softly and becomes louder |
| Decrescendo | begins loudly and becomes softer |
| Crescendo/Decrescendo | begins softly, peaks at a certain intensity and then becomes soft again |
| Decrescendo/Crescendo | begins loudly, becomes softer, then becomes loud again |
| Bolosystolic or (pansystolic) | stays same intensity through systole and diastole |
| Bolodiastolic | the same intensity throughout diastole; pandiastolic murmur |
Further characteristics of murmurs include the quality and pitch. The quality of a murmur may be harsh, blowing, musical or rumbling. The pitch may be described as high or low pitched. Other terms may also be: dull-sounding, sharp, others. In many cases, you may simply describe how the murmur sounds to you. Be descriptive and try to use established terms. However, be precise in location and changes in the sounds that you hear. Do not be afraid to say, “it is a swooshing murmur when the patient is lying on left side, and has a ‘tapping” sound when sitting up”. Describe exactly what you hear.
Types of Murmurs:
The heart murmur associated with mitral stenosis is caused by the flow of blood across the constricted mitral valve during the period of rapid ventricular filling. There are two periods of this rapid ventricular filling in the cardiac cycle. These are: early diastole, shortly after the opening of the atrioventricular valves; and immediately prior to the onset of systole just as the atria contract. This explains why there are two murmurs heard in mitral stenosis. The first is an early to middiastolic murmur and a presystolic murmur. There is also another distinct sound heard with the condition of mitral stenosis. This sound is referred to as the opening snap of mitral stenosis. Normally, the opening of the mitral valve is silent. In the presence of mitral stenosis, there is a sharp, high-pitched click can be auscultated. The click is best heard between the apex and the lower left sterna border.
The murmur of aortic insufficiency is caused by the backward flow of blood from the aorta into the left ventricle across an aortic valve that is incompetent. This backward pressure exerted by the blood in the aorta is the greatest, just after the closure of the aortic valve and progressively falls thereafter throughout diastole. The sound produced is described as regurgitation. The murmur usually begins immediately after S2 and can progress throughout the entire diastole. This murmur is best heard at the base of the heart and will often radiate to the apex.
The murmur will usually be very high pitched and will usually have a “blowing” quality; although it many times has a very harsh quality to the sound and may be very loud.
The third heart sound, S3 was discussed earlier as being normal in some adults and in children. In the case of a pathological S3, it may be noted with the event of damage to the myocardium. This heart sound, when auscultated, sounds like the gallop of a horse. Indeed, it is described as a gallop. The S3 creates an extra heart sound that can be rapid and very distinctive. The S3 G (S3 Gallop) is caused by early diastolic vibrations that are probably the result of ventricular distensibility associated with the myocardial damage. The S3 G can be best heard at the apex as a short, low-pitched sound. It may possibly be palpated, since it is associated with the ventricle and can create a “thrust” from the heart. A gallop rhythm is very suggestive of myocardial damage and the possible presence of early congestive heart failure.
Cardiac Arrhythmias:
An arrhythmia is described as an abnormal heartbeat. It might be caused by one or more of several factors:
- SA node – variation of the rate of discharge of the node
- Conduction defect – an abnormality of conduction of electrical impulses from sinoatrial node through the heart
- Myocardial irritability – initiation of contraction of heart muscle by impulse on a random area of the heart, other than SA node
The “average” person’s heart rate is usually 70 to 100 BPM, Beats Per Minute. However, we all know that some persons may have a normal heart rate that is slightly higher or lower than these normal ranges. Of course metabolism, exercise and other factors will affect a person’s normal heart rate. A rapid heart rate is called tachycardia, and a slower than normal rate is called bradycardia.
When assessing a patient’s heart rate, you must consider that the heart rate is also controlled by the sympathetic and parasympathetic nervous systems. The sympathetic nervous innervation increases the rate at which the SA node fires. The parasympathetic nervous innervation decrease the rate of firing and subsequently the heart rate slows. Normally, these two influences keep the heart rate in balance and produce a normal heart rate. However, in disease conditions, either or both of these nerves may dominate and produce a fast or a slowed heart rate.
The normal heart beat is also referred to as sinus rhythm, or being initiated in the sinoatrial node. Very specifically, if the rate is normal and the heart beat is a sinus rhythm, it is called “normal sinus rhythm”. Using this terminology, it would be easy to see why a rapid, but otherwise normal (sinus) rhythm, is called sinus tachycardia. Conversely, a slow, but otherwise normal (sinus) rhythm, is called sinus bradycardia. Both of these arrhythmias are not normal, but they usually are not severe or life-threatening.
The nurse might easily understand that sinus tachycardia could be caused as a normal reaction to anxiety. In fact, just being sick and in the hospital might produce anxiety and also sinus tachycardia. The nurse would need to assess the patient very carefully if a rapid heart rate is present; especially if there are no adverse clinical signs or symptoms present. Of course, an EKG tracing and interpretation would be necessary to absolutely confirm that only sinus tachycardia is present, and that there is no immediate danger to the patient.
Factors that affect the sympathetic nervous system are: anxiety, fear, fever, extreme physical exercise, others. These conditions will generally cause an increase in the sympathetic stimulation of the SA node and subsequently, tachycardia.
Factors that affect the parasympathetic nervous system will induce a slowed heart rate. The parasympathetic nervous system exerts its influence through the vagus nerve. This stimulation of the vagus nerve will cause bradycardia.
In summary, prepare the patient; take vital signs and the history of the patient before you auscultate the heart. Compare your findings to what a normal heart sounds like. Then, report findings, especially if the patient has adverse clinical systems, such as cyanosis or some other important symptom.