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Pulmonary Circulation
Published in Wilmer W Nichols, Michael F O'Rourke, Elazer R Edelman, Charalambos Vlachopoulos, McDonald's Blood Flow in Arteries, 2022
Like the systemic circulation, the pulmonary circulation receives the same blood flow from the heart with the same periodicity and at the same time. There the similarity ends. The main functional difference was stressed by Harvey in 1628, i.e. that the pulmonary arteries carry blue venous blood, and the ascending aorta carries red oxygenated blood. From the hemodynamic point of view, the main differences between the right and left heart circulations are as follows.
Electrophysiology
Published in A. Bakiya, K. Kamalanand, R. L. J. De Britto, Mechano-Electric Correlations in the Human Physiological System, 2021
A. Bakiya, K. Kamalanand, R. L. J. De Britto
The cardiopulmonary system consists of blood vessels that carry nutrients and oxygen to the tissues and removes carbon dioxide from the tissues in the human body (Humphrey & McCulloch, 2003; Alberts et al., 1994). Blood is transported from the heart through the arteries and the veins transport blood back to the heart. The heart consists of two chambers on the top (right ventricle and left ventricle) and two chambers on the bottom (right atrium and left atrium). The atrioventricular valves separates the atria from the ventricles. Tricuspid valve separates the right atrium from the right ventricle, mitral valve separates the left atrium from the left ventricle, pulmonary valve situates between right ventricle and pulmonary artery, which carries blood to the lung and aortic valve situated between the left ventricle and the aorta which carries blood to the body (Bronzino, 2000). Figure 3.9 shows the schematic diagram of heart circulation and there are two components of blood circulation in the system, namely, pulmonary and systemic circulation (Humphrey, 2002; Opie, 1998; Milnor, 1990). In pulmonary circulation, pulmonary artery transports blood from heart to the lungs. The blood picks up oxygen and releases carbon dioxide at the lungs. The blood returns to the heart through the pulmonary vein. In the systemic circulation, aorta carries oxygenated blood from the heart to the other parts of the body through capillaries. The vena cava transports deoxygenated blood from other parts of the body to the heart.
Basic medicine: physiology
Published in Roy Palmer, Diana Wetherill, Medicine for Lawyers, 2020
The heart is the muscular pump that drives blood around the body. It has long been known that blood will spurt from a cut artery under high pressure, but it was thought to oscillate to and fro until William Harvey showed that blood circulates from small arterial branches through tiny vessels in the tissues (capillaries) before being collected by veins and returned to the heart The dynamo behind this circulation is the heart, which contracts 60–80 times per minute throughout an individual’s life. The heart contains four chambers and is responsible for two separate circulatory systems (Figure 1.1). The systemic circulation supplies all the organs in the body with oxygenated blood, while the pulmonary circulation delivers exhausted blood to the lungs where it is replenished with oxygen. The heart chambers comprise two atria which collect the blood and pass it through valves into the two ventricles, which contract forcefully to distribute blood throughout the body. The cardiac cycle consists of diastole, the phase of filling, and systole in which contraction of the atria is immediately followed by contraction of the ventricles.
Neurologic conditions in Hereditary Hemorrhagic Telangiectasia with pulmonary arteriovenous malformations: Database study
Published in Canadian Journal of Respiratory, Critical Care, and Sleep Medicine, 2023
Chester Lau, Joel Agarwal, Ben Vandermeer, W. Ted Allison, Thomas Jeerakathil, Dilini Vethanayagam
An estimated 35–40% of HHT subjects have pulmonary arteriovenous malformations (PAVMs), consisting of abnormal connections between the feeding artery(ies) and draining vein(s).9 These fragile and dilated vessels allow blood contents from the pulmonary circulation to bypass capillary beds and travel toward the systemic circulation, preventing gas exchange.9,12 PAVMs result in the physiologic consequence of intrapulmonary right-to-left shunt (RLS), causing air and/or particulate emboli to traverse through the bloodstream into the cerebral vessels.13 This may lead to a plethora of neurological conditions, including migraines, seizures, ischemic (embolic) stroke, transient ischemic attack (TIA) and cerebral abscess.14 These neurologic conditions may also be dependent on PAVM shunt grade.9,13,15–17 Other clinical features of PAVMs include clubbing, dyspnea and hypoxemia; however, many patients with PAVMs are asymptomatic.12
The role of serial right heart catheterization in risk stratification and management of pulmonary arterial hypertension
Published in Expert Review of Cardiovascular Therapy, 2022
Dikshya Sharma, Ravi J Shah, Jayakumar Sreenivasan, Paritosh Kafle, Rahul Gupta, Avi Levine, Gregg M. Lanier, Wilbert S. Aronow
Pulmonary arterial hypertension (PAH) is a severe and progressive disease associated with increased vascular resistance in the pulmonary circulation. Despite the significant advancement of multiple medical therapies for treatment over the past couple of decades, management requires treatment by a specialist knowledgeable in the disease state and advanced treatment modalities, and prognosis remains guarded in most cases. A more recent change in the treatment of PAH includes regular assessment of disease progression and clinical risk, and escalation of therapy as indicated to reduce the risk of adverse outcomes. Early risk assessment is crucial to identifying the highest risk patients, who may need advanced therapies such as parenteral medications or lung transplantation, and in timely initiation of pharmacotherapy.
Right Ventricular-Pulmonary Arterial Coupling and Outcomes in Heart Failure and Valvular Heart Disease
Published in Structural Heart, 2021
Bahira Shahim, Rebecca T. Hahn
Compared with the systemic circulation, pulmonary circulation has a much lower vascular resistance, greater pulmonary artery distensibility, and a lower peripheral pulse wave reflection coefficient.12 Pulmonary vascular impedance reflects the opposition to pulsatile flow, and determines, together with pulmonary vascular resistance (PVR), the RV afterload.9 RV afterload is reflected by arterial elastance (Ea), a load-independent measure of “total” ventricular afterload (both pulsatile and resistive components). It is measured as RV end-systolic pressure divided by stroke volume.24 PVR is a measure of the resistance of both capillaries and veins and is calculated as the difference between the mean pulmonary arterial pressure and pulmonary capillary wedge pressure, divided by the cardiac output. In the normal RV, mean pulmonary artery pressure is a reasonable approximation of end-systolic pressure. Thus, in the normal RV Ea could be estimated as PVR x heart rate.25 Although PVR represents only the resistive component of Ea, and pulmonary arterial compliance represents the pulsatile component, the latter contributes only ~23% to total afterload26 in normal patients and those with arterial pulmonary hypertension (PH) and support the use of the simplified formula. However, if post-capillary PH is present, the pulsatile component of Ea increases27 and stroke work is significantly reduced.28 Taking into account both resistive and pulsatile components of Ea may then be more important.