Which physical examination technique is the nurse performing when using the bell of a stethoscope to hear a patients heart sound?

Evaluating a patient who presents with cardiac symptoms is a complex and multi-step process. In addition to obtaining a thorough history, a detailed cardiac examination is of paramount importance. In the era where medical technologies advance rapidly, one may think that savvy medical diagnostics such as echocardiography or cardiac CT-scan can replace a thorough cardiac exam readily. But one must remember, a combination of a comprehensive history and detailed cardiac exam can diagnose almost 80% of cardiac disease. The decline of physical exam skills in the new generation of physicians is a well-documented phenomenon.[1] A good physical exam can save lives by rapid diagnosis and treatment as most of the diagnostic studies take time to result. Here we discuss the four pillars of the cardiac exam, i.e., history taking as well as inspection, palpation, and auscultation.

Cardiac Anatomy/Physiology:

To perform a successful physical exam, one must understand the structural anatomy of the heart. The heart is a thoracic organ-confined between the lungs, above the diaphragm. It's divided into four chambers, two atria and two ventricles, respectively. The atria are separated by the interatrial septum, while the interventricular septum separates the ventricles. 

The right atrium receives deoxygenated blood from superior and inferior vena cava. It then passes through the tricuspid valve into the right ventricle. From there, deoxygenated blood transverses the pulmonic valve into the pulmonary artery through which it goes to the lungs for gas exchange. Oxygenated blood is then pushed through the pulmonary vein into the left atrium, which then goes through the mitral valve into the left ventricle. The high-pressure left-sided system then pumps the blood through the aortic valve into the aorta and throughout the body. 

The pressure of the ejected blood against the arterial wall generates blood pressure along with peripheral vascular resistance. Systolic blood pressure is the pressure when the heart is beating and is the maximum pressure in the arteries. Diastolic blood pressure is the pressure when the heart is relaxing, is the minimum pressure in the arteries, and depends on peripheral vascular resistance.[2] Blood pressure also depends on stroke volume, blood velocity, compliance of the arteries, and blood viscosity.

Heart sounds are typically portrayed as a “lub and a dub” sound. “Lub” being the first heart sound (S1), marks the beginning of systole and is generated by the turbulence caused by the closing of the mitral and tricuspid valves. “Dub” is the second heart sound (S2), marks the end of systole and the beginning of diastole and is generated by the closure of aortic and pulmonic valves. 

The position of heart valves relative to the chest wall will dictate the optimal position for auscultation. The valves are best auscultated as follows[3]:

• Aortic: second intercostal space, right sternal border

• Pulmonic: second intercostal space, left sternal border

• Tricuspid: left lower sternal border

• Mitral: fifth intercostal space, midclavicular line (cardiac apex)

History:

A thorough history and review of systems can help diagnose specific cardiac diseases and can help differentiate it from diseases of other organ systems. The important symptoms of cardiac disease are as follows. 

• Chest pain: The hallmark of cardiac disease, however, it can also result from pulmonary, GI, and musculoskeletal disorders. A detailed history is imperative to differentiate cardiac anginal chest pain from the rest. The typical description of angina is retrosternal and diffuse. Radiating to the left arm/jaw. Aching, pressure-like sensation as if “someone is sitting on the chest.” Exacerbated by exertion and relieved by rest and nitroglycerin. 

• Palpitations: This is defined as a fluttering, uncomfortable sensation in the chest that is usually associated with arrhythmias.[4] It feels as if the “heart has skipped a beat.”

• Dyspnea (shortness of breath):  Paroxysmal nocturnal dyspnea and dyspnea on exertion are usually the results of congestive heart failure. 

• Syncope: Transient loss of consciousness that results from hypoperfusion to the brain. Cardiac syncope has different etiologies. Syncope related to exertion can be due to reduced cardiac output states due to obstructive lesions such as hypertrophic obstructive cardiomyopathy, aortic stenosis, or arrhythmias.[5] Syncope of sudden onset without warning or “prodrome” is more likely to be due to arrhythmia. 

• Fatigue: While not a specific symptom of cardiac disease, this is a common symptom of chronic decreased cardiac output state, such as in congestive heart failure.

• Edema: Symmetric pitting edema of the lower extremities that worsens as the day progresses is a common symptom in patients with congestive heart failure. If the patient is bedridden, other gravity-dependent sites should be checked, such as the buttocks.[6]

Physical Exam:

Equipment needed for cardiac examination are:

• Stethoscope

• Sphygmomanometer

• Ruler

• Penlight

The cardiac exam generally includes inspection, palpation, and auscultation. The examiner should be on the right side of the bed, and the head of the bed can be slightly elevated for patient comfort. 

Inspection:

Begin by inspecting the general appearance of the patient. Then one can move on to examining the skin, nails, mouth, neck, and extremities. 

• General: Is the patient well-nourished (advanced heart failure can be associated with cachexia)? Is the patient in distress? Is breathing comfortable? 

• Skin: The skin can display many clues about cardiac disease. Inspect the temperature of the skin, cool skin points towards poor perfusion, which is many times due to reduced cardiac output. Look for xanthomata, associated with hypercholesterolemia. Acanthosis nigricans can be present in insulin resistance states, which has a strong correlation with heart disease. 

• Nails: Splinter hemorrhages are reddish-brown lines in the nail bed, which are classically associated with infective endocarditis. This finding is often non-specific and can be seen in many other conditions as well.

• Mouth: Palatal petechiae are also associated with infective endocarditis. A high arched palate is associated with congenital heart disease, such as mitral valve prolapse. 

• Neck: Abnormalities in the jugular venous pulse can lead clinicians towards diseases such as atrial fibrillation, tricuspid regurgitation, tricuspid stenosis, pulmonary artery hypertension, pulmonic stenosis, and cardiac tamponade.[7][8] Looking for jugular venous distention and performing the hepatojugular reflex can give a rough estimation of right-sided heart pressures.

• Extremities: Dependent edema is an important finding, as mentioned above. Pitting edema should be graded from 1+ to 4+, depending on the depth and how long the indentation persists.[6]

Palpation:

Palpation includes assessing the arterial pulse, measuring blood pressure, palpating any thrills on the chest, and palpating for the point of maximal impulse.

• Arterial pulse: When palpating the arterial pulse, the examiner should be able to gather the rate, rhythm, and characteristics. To determine the rate, the examiner should count the radial pulse for 30 seconds and multiply by 2. This process works to give a relatively accurate rate unless an irregularly irregular rate is present such as in atrial fibrillation, in which case, auscultation of the heart for the rate should be done. Rhythm should be determined as regular, regularly irregular, or irregularly irregular. Pulse characteristics include contour and amplitude of the pulse. Contour refers to the shape of the pressure wave; normally, it has a steep upward stroke and a smooth downward stroke. For example, a steep and robust upstroke is known as a Waterhammer pulse and is present in aortic regurgitation. The amplitude of the pulse is the highest point of the upstroke. It can vary in congestive heart failure. Of note, when palpating a carotid pulse, always auscultate to check for a bruit first.

• Blood pressure: This is doable at the bedside with a sphygmomanometer, which is a cuff with an inflatable balloon and a manometer to measure the pressure inside the balloon.  It is placed classically over the brachial artery, the cuff gets inflated, and blood pressure gets detected by the auscultatory appearance and disappearance of Korotkoff sounds.[2]

• Thrills: These are vibratory sensations felt on the skin overlying the heart, which indicates turbulence; this can be felt in loud murmurs and are necessary for murmur grading.

• Point of Maximal Impulse: To palpate the PMI, with the patient in the upright position, the examiner should place their fingertips in the fifth intercostal space in the midclavicular line. If they do not feel it there, the examiner should move their hand until they do feel it. PMI is usually within 10 cm of the midclavicular line. One should note if PMI is displaced, as this can indicate cardiomegaly.[9]

Auscultation:

Auscultation of heart sounds is the cornerstone of any physical exam. It is usually with the assistance of a stethoscope. Most stethoscopes have two areas, the bell, and the diaphragm. The bell should be applied lightly to the skin and is useful in identifying low-pitched sounds such as gallops, murmurs of AV stenosis, and bruits. The diaphragm should be pressed tightly against the skin and helps identify high-pitched sounds such as valve closures, regurgitant murmurs, and systolic clicks.

The examiner should perform auscultation in four standard positions; supine, left lateral decubitus, upright, upright leaning forward. Generally, the examiner should start with the patient in the supine position and listen to all the cardiac areas in the aortic, pulmonic, tricuspid, and mitral regions in the locations previously described for S1 and S2 sounds and any systolic murmurs. While auscultating at the Left lower sternal border, one should determine if there is an S3 or S4 heart sound heard. S3 heart sound can be physiologic in children and athletes but can also be heard in patients with heart failure. S4 heart sound is produced from blood ejecting into a stiff ventricle and is also present in heart failure. The examiner should then turn the patient into the lateral decubitus position to listen for the low pitched diastolic murmur of mitral stenosis. The patient then turns upright, and all the areas are examined with the diaphragm of the stethoscope to listen for S1 and S2 sounds and any systolic and diastolic murmurs. The patient then should be leaned forward and asked to hold their breath; the examiner should then listen for the murmur of aortic regurgitation as well as any friction rubs. These sounds are extracardiac, usually originating in the pleura or the pericardium, and have a sound similar to scratching on sandpaper. These may result when there is irritation of these membranes as in pleuritis or pericarditis. Of note, the examiner should pay close attention to the influence of breathing on the nature and intensity of heart sounds. Most murmurs coming from the right side of the heart become accentuated with inspiration. 

With auscultation of heart sounds, the examiner must be able to identify and describe murmurs. Murmurs can be either systolic or diastolic, so their timing relative to S1 and S2 is crucial. The timing of the heart sounds corresponding to the carotid pulse can help reliably identify S1 and S2. The sound that precedes the carotid pulse is S1, whereas the sound that follows it is S2. For this to work, only the carotid pulse should be used, not the radial, as there is a significant delay between the sound of S2 and the pulsation. 

If a murmur is present, the following features require inspection; timing, location, radiation, duration, intensity, pitch, quality, relation to respiration, and maneuvers such as Valsalva or hand grip.[10] The timing of murmurs relative to systole and diastole is critical, i.e., a murmur beginning with S1, lasting through to S2, is likely a holosystolic or pansystolic murmur. A systolic ejection murmur begins with S1 but ends before S2. Does the murmur peak, or is it uniform throughout? The murmur of aortic stenosis classically is described as a crescendo decrescendo murmur; it has a peak in the middle.[10] Examiner must also identify in which area the murmur is bed heard and whether the murmur has radiation to other areas such as the axilla, neck, or back. The murmur should then be graded on a level from I to VI. The Levine murmur grading system is the gold standard of documenting intensity[11]

• I: lowest intensity, often not audible

• II: soft but heard in all positions

• III: Moderate intensity, heard easily but no thrill

• IV: Moderate intensity, with a thrill

• V: High intensity, easily audible with a stethoscope lightly placed on the chest, with a thrill

• VI: Highest intensity, audible with the stethoscope not touching the skin, with a thrill

In an era of rapidly advancing medical diagnostic technology, it can be easy to overlook history and physical examination. Clinicians must be proficient in these skills to develop differentials and THEN order tests to confirm or refute differentials. Many diseases can be diagnosed solely based on good history taking and physical exam skills. The cardiac examination, in particular, is of vital significance when it comes to a thorough evaluation of the heart and differentiating between cardiac disease and diseases of other origins. Furthermore, the physical contact between the clinician and the patient during an encounter can also help create a psychological bond that provides reassurance and generates trust.

All healthcare workers should know how to perform a physical exam. The cardiac exam can quickly provide important information that can aid in the rapid diagnosis of many life-threatening diseases. In the inpatient setting, the cardiac exam should be a part of routine history and physical during admission and should be done daily. In the outpatient setting, the cardiac exam is still the most appropriate method to screen for cardiac disease and establish a diagnosis.