What is the arterial pressure when the left ventricle is at the peak of its contraction?
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The cardiac cycle represents the hemodynamic and electric changes that occur in systole and diastole. It has many phases. Phases of the Cardiac Cycle
Heart SoundsNormal pressures in various chambers of the heart The first heart sound (S1) represents closure of the atrioventricular (mitral and tricuspid) valves as the ventricular pressures exceed atrial pressures at the beginning of systole (point a). S1 is normally a single sound because mitral and tricuspid valve closure occurs almost simultaneously. Clinically, S1 corresponds to the pulse. The second heart sound (S2) represents closure of the semilunar (aortic and pulmonary) valves (point d). S2 is normally split because the aortic valve (A2) closes before the pulmonary valve (P2). The closing pressure (the diastolic arterial pressure) on the left is 80 mmHg as compared to only 10 mmHg on the right. This higher closing pressure leads to earlier closure of the aortic valve. In addition, the more muscular and stiff "less compliant" left ventricle (LV) empties earlier than the right ventricle. The venous return to the right ventricle (RV) increases during inspiration due to negative intrathoracic pressure and P2 is even more delayed, so it is normal for the split of the second heart sound to widen during inspiration and to narrow during expiration. Clinically, this is more remarkable with slow heart rates. The third heart sound (S3) represents a transition from rapid to slow ventricular filling in early diastole. S3 may be heard in normal children. The fourth heart sound (S4) is an abnormal late diastolic sound caused by forcible atrial contraction in the presence of decreased ventricular compliance.
Abnormally wide splitting of S2 may occur in: a) RV volume overload, such as atrial septal defect (ASD) and anomalous pulmonary venous connection. In these cases, the split is usually wide and "fixed" with no difference between inspiration and expiration due to fixed RV volume (see ASD section) b) RV outflow obstruction, such as pulmonary stenosis (PS) c) Delayed RV depolarization such as complete right bundle branch block Narrow splitting of S2 occurs in: a) Pulmonary hypertension as the pulmonary valve closes earlier due to high pulmonary resistance b) Mild to moderate aortic stenosis as the A2 is delayed Single S2 may occur: a) If one of the semilunar valves is missing, as in pulmonary or aortic valve atresia and truncus arteriosus b) If both valves close simultaneously as in pulmonary hypertension with equal pulmonary and aortic arterial pressures c) If both valves close simultaneously as in double outlet single ventricle or in large VSD with equal ventricular pressures d) Posterior displacement of the pulmonary valve away from the chest wall as in d-TGA Paradoxical splitting of S2 (P2 is heard before A2) occurs in: a) Severe aortic stenosis b) Left bundle branch block In both conditions, the aortic valve (A2) closes after the pulmonary valve (P2). Since the respiration only affects P2, its effect in paradoxical splitting is the opposite of normal, i.e. inspiration causes narrow splitting while expiration causes wide splitting of S2. Heart MurmursMurmurs are additional sounds generated by turbulent blood flow in the heart and blood vessels. Murmurs may be systolic, diastolic or continuous. Grading of systolic mumers based on thier intensity
Systolic murmurs are the most common types of murmurs in children and based on their timing within systole, they are classified into: a) Systolic ejection murmurs (SEM, crescendo-decrescendo) result from turbulent blood flow due to obstruction (actual or relative) across the semilunar valves, outflow tracts or arteries. The murmur is heard shortly after S1 (pulse). The intensity of the murmur increases as more blood flows across an obstruction and then decreases (crescendo-decrescendo or diamond shaped). Innocent murmurs are the most common cause of SEM (see below). Other causes include stenotic lesions (aortic and pulmonary stenosis, coarctation of the aorta, Tetralogy of Fallot (TOF)) or relative pulmonary stenosis due to increased flow from an ASD
Crescendo decrescendo murmur b) Holosystolic (regurgitant) murmurs start at the beginning of S1 (pulse) and continue to S2. Examples: ventricular septal defect (VSD), mitral and tricuspid valve regurgitation.
Holosystolic murmur c) Decrescendo systolic murmur is a subtype of holosystolic murmur that may be heard in patients with small VSDs. In the latter part of systole, the small VSD may close or become so small to not allow discernible flow through and the murmur is no longer audible.
Decrescendo murmur Diastolic murmurs are usually abnormal, and may be early, mid or late diastolic.
Continuous murmurs are heard during both systole and diastole. They occur when there is a constant shunt between a high and low pressure blood vessel. Examples: patent ductus arteriosus (PDA) and systemic arterio-venous fistulas. This may also occur in surgically placed shunts such as a Blalock-Tauussig (BT) shunt between the aorta and the pulmonary artery. Innocent murmurs are common in children and have the following characteristics:
Summary of Heart Murmurs What is the peak pressure in the left ventricle?Normal Pressures in the Heart and Great Vessels. What is arterial pressure at the peak of ventricular contraction called?Systolic pressure is the maximum blood pressure during contraction of the ventricles; diastolic pressure is the minimum pressure recorded just prior to the next contraction. The blood pressure is usually written as the systolic pressure over the diastolic pressure (e.g., 120/80 mm Hg).
What pressure does the left ventricle generated during a contraction?When the left ventricle (LV) contracts, it generates a systolic blood pressure of 100-140 millimeters of Hg (mm Hg). The aortic diastolic pressure is usually 60-90 mm Hg. The LV/aortic pressure gradient causes blood to pass through the aortic valve.
What is the normal peak pressure of the left ventricle quizlet?In order to initiate ventricular ejection into the aorta, the left ventricle must at first overcome 70 mmHg, but as volume continues to flow into the aorta, the pressure rises up to 120 mmHg. At peak systole, to continue blood flow into the aorta, ventricular pressure must exceed 120 mmHg.
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