Cardiovascular Concept Lab Notes

Cardiovascular Concept Lab Physiology of the Heart  The heart consists of 4 chambers: the right & left atria which receive blood, & the right & left ventricles which pump it out. o The right atrium (RA) receives the systemic venous return from the inferior vena cava (IVC) & superior vena cava (SVC). This blood is deoxygenated from its travel through the body. The RA collects this blood & directs it into the right ventricle (RV) through the tricuspid valve. o The right ventricle (RV) is the pumping chamber on the right side of the heart. It pumps the deoxygenated blood through the pulmonic valve into the pulmonary artery (PA). From there the two main branches of the PA deliver the pulmonary cardiac output to the lungs for oxygenation. o The left atrium (LA) collects the pulmonary venous return from four main pulmonary veins. Remember these veins contain oxygenated blood (while systemic veins contain deoxygenated blood). The LA directs this blood through the mitral valve into the left ventricle (LV). o The left ventricle (LV) is the pumping chamber on the left side of the heart. Generating roughly 5x the pressure of the RV, it pumps the oxygenated blood through the Aortic Valve into the Aorta (Ao), & throughout the body.  The four cardiac valves are vital to the movement of blood in the heart. By opening & closing at specific moments within the cardiac cycle they prevent the backflow of blood. o Normal heart sounds are caused by changes in blood flow as the valves close. The first heart sound (S1) occurs when the mitral & tricuspid valves close. The second heart sound (S2) happens when the closing of the aortic & pulmonic valves. Areas of Auscultation  While listening to (auscultating) heart sounds, it is standard practice to use a stethoscope. o When auscultating for the aortic area, place your stethoscope on the 2nd right intercostal space at the upper right sternal border. o When auscultating for the pulmonic area, place your stethoscope on the 2nd left intercostal space at the upper left sternal border. o When auscultating for Erb’s point, place your stethoscope on the 3rd left intercostal space at the medial left sternal border. It can only be heard in the left lateral recumbent position. o When auscultating for the tricuspid area, place your stethoscope on the 4th left intercostal space at the left sternal border. o When auscultating for the mitral area (sometimes called the apical area), place your stethoscope at the apex of the heart on the 5th left intercostal space at the midclavicular line. Precordium Assessment Sounds       Ventricular Gallop (S3) o A ventricular gallop is the third heart sound, S3. This low frequency vibration occurs after S1 & S2 & seems to result from the change in blood flow in diastole when rapid filling ends & slow filling starts. o When listening for S3, the heart sounds resemble the pronunciations of the word Ken-TUCK-y, with the y representing S3. S3 has been described as testing “the auscultatory skills of the examiner” because of its low frequency & intensity as well as interference of the normal sounds in the chest from the lungs & abdomen. It is best heard with the bell of the stethoscope. Sometimes it is normally heard in those under the age of 40 & trained athletes. Atrial Gallop (S4) o An atrial gallop is the fourth heart sound, S4. It is a low frequency sound that occurs in late diastolic filling due to atrial contraction. This causes vibrations in the ventricular walls & happens just before S1, making it difficult to hear. o If loud, it can indicate pathology, & it resembles the pronunciation of the word TEN – nes – see (where the TEN is S4). When it is clearly heard it can indicate an increased resistance to ventricular filling. Sometimes S4 can occur normally in people older than 40, especially after exercise. Tachycardia (rapid resting heart rate) o Considered an arrhythmia, or disorder of the normal cardiac rhythm, Tachycardia is a resting heart rate (HR) of over 100 beats per minute. o There are a number of factors that can cause tachycardia. Some of these factors are not particularly serious & have no associated health complications (such as tachycardia from stress due to illness). However more serious issues can arise if tachycardia is chronic & left untreated. Heart function can be disrupted & serious complications can arise. Bradycardia (slow resting heart rate) o Also, an arrhythmia, Bradycardia is a resting heart rate (HR) of less than 60 beats per minute. o In many situations bradycardia does not cause any symptoms or complications (i.e., healthy, young athletes have slower heart rates). However, it can be a sign of dysfunction of the heart’s electrical system. Pericardial Friction Rub o Pericardial friction rub is a sound generated from inflammation of the pericardial sac as it rubs against the linings surrounding the heart, & not really a heart sound. o Pericarditis is an inflammatory disease of the pericardium, which causes the membranes to become sticky, producing friction when the heart beats or when the patient breathes. This friction produces the sound known as pericardial friction rub. It is a scratching, grating, high frequency sound that is heard in both systole & diastole. It is seeming to be best heard with the diaphragm of the stethoscope at the left lower sternal border. Murmurs o Abnormal heat sounds can also include murmurs, which are produced by turbulent blood flow. Murmurs are normally heard during auscultation, & they take practice to identify. o Innocent (or functional) murmurs are non-cardiac murmurs related to pregnancy, hyperthyroidism, exercise, & anemia. It is most often heard in children. This type of murmur is normally heard with systole in the pulmonic precordial area. o Pathological murmurs are due to congenital or valvular defects. Specific valvular defects can be identified by their timing (during S, systolic, S, diastolic) & the auscultation region where they are heard.