Part II: Assessment Techniques, Con't.
A heart murmur is a very general term used to describe any one of the verity of abnormal sounds heard in the heart due to turbulent or rapid blood flow through the heart, great blood vessels, and/or heart valves (whether the heart valves are normal or are diseased). Most nurses associate murmurs with an abnormal heart valve. However, there are a variety of other conditions that can cause murmurs. Murmurs can also be caused by the forward flow of blood across a constricted or otherwise irregular valve, or into a dilated heart chamber or dilated vessel. They can also be caused by the backward flow of blood through an incompetent valve or a septal defect murmurs are usually described as a “rushing” or “swooshing” sound. Murmurs are usually related to defect in valves or ventricular septal defect, or atrial septal defect.
When ausculatining murmurs, the nurse should record the timing, characteristics, location, and radiation of the murmur. Characteristics include: loudness, intensity, pitch, and quality of the murmur. These assessment factors are discussed in more detail later in the course.
The bell of the stethoscope may be used for low frequency sounds (they are better amplified by the bell). S3 and S4 gallops are generally low-pitched sounds and are heard best with the bell of the stethoscope while the patient is stretched out on his left side. Many nurses prefer to auscultate the heart sounds a second time with the bell of the stethoscope in order to detect any sounds that might be missed with the diaphragm. S3 gallop, the ventricular gallop, occurs at the end of ventricular systole. It is often caused by the sound of blood prematurely rushing into the ventricle that is stiff or dilated due to heart failure, coronary artery disease, or pulmonary hypertension.
Sounds described as “clicks” are extra sounds often heard in those patients with mitral valve prolapsed, aortic stenosis, or those with prosthetic heart valves. Opening “snaps” are usually caused by mitral stenosis or stenosis of the tricuspid valves.
Sounds referred to as “rubs” occur when the visceral and parietal layers of the pericardium rub together. The sound is produced when inflammation is present due to uremic pericarditis, myocardial infarction, or other inflammatory condition.
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 recal that the interval between S1and S2 corresponds to the systolic phase, then a murmer that is heard between S1 and S2 wuld be called a systolic murmur. Then a diastolic murmur would be called a murmer 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 descriving exactly when in the phase it occurs. The murmur can be described as:
These above terms describe murmurs in the exact position that they fall I 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 called pansystolic), is used to describe a murmur heard throughout the entire systolic phase (S1 to S2). Similarly, 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 has experience in listening to a variety of “normal” variation of normal heart sounds. 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 sat 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 and affect heart rate and force of the closure of the valves. Loudness, of course, is also affected. Note the following changes due to disease:
These are some disease conditions and the resulting change in the heart sounds. The term murmur refers generally to any “extra” or unusual heart sounds. Most nurses will not be expected of 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 from your nurses’ 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 I the cardiac cycle, loudness, pitch, the location of the 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 world 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 Ausculation of Heart Sounds
S1: Supine or lying with upper body slightly elevated.
S2 Supine or lying with upper body slightly elevated.
S1: Start at mitral or tricuspid area; loudest at apex (mitral).
S1 S1 split best heard at lower left sterna border.
Differentiating S1 from S2
S1 occurs with the downstroke of the R wave on the EKG. It also occurs simultaneously with the carotid impulse upstroke.
S2 Follow the T wave on the EKG and occurs as the carotid pulse wave fades.
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
All of the ratings are very subjective.
Intensity of heart murmurs:
Further characteristics of murmurs include the quality and the pitch. The quality of a murmur may be described as harsh, blowing, musical, rumbling. The pitch may be described as high or low pitched. Other terms may also be used, such as: dull-sounding, sharp, and others. In many cases, the nurse may simply describe how the murmur sounds to you. Be very descriptive and try to use established terms. However, you should also be precise in location and changes I the sounds that you hear. Do not be afraid to say “it is a swooshing murmur when the patient is lying on left side, than has a “tapping” sound with sitting upright.” 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 filing. There are two periods of this rapid ventricular filling in the cardiac cycle. These are: early diastole, shortly after the opening of the atriventricular valves; and immediately prior to the onset of systole just s the atria contract. This explains why there are two murmurs heart in mitrial 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, this opening of the mitral valve is silent. In the presence of mitral stenosis, there is a sharp, high-pitched click that can be ausculated. 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 fall thereafter thought diastole. The sound produced is described as regurgitation. The murmur usually beings 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 at 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 an in children. In the case of a pathological S3, it may be noted with ether vent of damage to the myocardium. This heart sound, when ausculated, sounds like the gallop of a horse. Indeed, it is described as a gallop. The S3 creates and 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 dispensability 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, as stated, and the possible presence of early congestive heart failure.
An arrhythmia is described as an abnormal heartbeat. An arrhythmia might be caused by one or more of several different factors:
The “average” person’s heart rate is usually 70 – 100 beats per minute (BPM). However, we all know that some persons may have a normal heart rate that is slightly higher or lower then 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 innervations increases the rate at which the SA node fires. The parasympathetic nervous innervation decreases the rate of firing and subsequently the heart rate 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 nods. 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 are usually 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 now immediate danger to the patient.
Factors that affect the sympathetic nervous system are: anxiety, fear, fever, extreme physical exercise, other. 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 history of the patient before ausculating the heart. Compare findings to normal heart sounds. Then, report findings, especially if the patient has adverse symptoms, such as cyanosis or some other important symptoms.