View clinical trials related to Fontan Physiology.
Filter by:In patients with Fontan circulation blood is not pumped to the lungs from a ventricle. Instead the superior vena cava and inferior vena cava is connected to the pulmonary artery and blood flow to the lungs occurs passively along this Fontan pathway. This passive blood flow to the lungs occurs best when the patient is breathing on their own (spontaneous ventilation). However for certain surgeries and procedures patients need to have an endotracheal tube inserted and need to be muscle relaxed and receive positive pressure ventilation. Prior studies have shown that positive pressure ventilation can reduce blood flow to the lungs and consequently blood returning to the heart resulting in less blood pumped out to the rest of the body (cardiac output). The purpose of this study is to investigate if changing the volume of the positive pressure ventilation (tidal volume) affects blood flow to the lungs and cardiac output in patients with Fontan circulation.
The goal of this study is to evaluate if vasopressin can elevate systemic arterial blood pressures without having a significant effect on pulmonary arterial pressures. Because patients who have undergone Fontan procedures rely on low pressures across the pulmonary vascular bed to maintain cardiac output, vasoactive agents that concomitantly increase systemic and pulmonary pressures may have a deleterious effect in this specific patient population. Hypothesis: In patients with Fontan physiology, vasopressin will increase systemic BP by 20% above baseline, without increasing the transpulmonary gradient.
The human heart has 4 chambers: 2 collecting chambers (atria) and 2 pumping chambers (ventricles) to allow blood flow within two distinct circuits: "pulmonary" and "systemic". The pulmonary circuit directs the blood to the lungs to receive oxygen and the systemic circuit delivers oxygen-rich blood throughout the body. In children born with a single ventricle, blood from these two circuits mixes within the heart resulting in lower oxygen levels in the blood delivered to the body (cyanosis). The Fontan procedure is a palliative surgery which bypasses the need for a ventricle to deliver blood to the lungs, as blood from the body flows passively to the lungs by a man-made connection (whereby two large body veins [cavae] are sewn to the pulmonary arteries), thereby preventing mixing of blood through restoration of two distinct circuits without mixing of blood. Although the Fontan operation effectively eliminates cyanosis and enables survival into adulthood, increased systemic venous pressure is an unavoidable systemic complication and low cardiac output (CO) is pervasive finding. Despite excellent pediatric surgical results, the risk of late complications and death dramatically increases in the decades following Fontan surgery. A chronically low CO state secondary to decreased forward flow of blood to the lungs can result in end-organ dysfunction and shortened life expectancy. Short of heart transplantation, deemed suitable only for a minority of patients, effective therapies for low CO are largely absent. The investigators aim to investigate a novel, non-invasive, ambulatory therapy which can augment CO. Specifically, external suction is applied intermittently to the chest wall, much like a vacuum, to increase CO, called negative pressure ventilation (NPV) using a Cuirass® ventilator (Hayek Medical). Although used in patients with lung disease, the investigators' proposal is to evaluate this novel, portable, ventilation system would be the first study of its kind in adults with congenital heart disease, specifically those with a Fontan palliation.