to reduce leading to a reduction of systemic blood flow; this causes tiredness. Reduced exercise tolerance: symptoms also caused by decreased systemic (oxygenated blood to the rest of the body) flow. Just as with fatigue, when the patient has MS and the blood flows from the left atrium to the right atrium, the forward blood flow into the left ventricle is reduced leading to a reduction of systemic blood flow; this causes tiredness and hence a reduced exercise tolerance. Weight gain: this is commonly found in patients with large ASD and can be a symptom of developing right-sided heart failure. As there is a chronically increased left-to-right blood flow through the atria, this will lead in the future to right-sided heart failure. Ankle edema: This is also caused by a large ASD and has the same symptoms and causes as seen in weight gain and right upper quadrant pain. As blood flow is not happening correctly and the heart is pumping under strain, pooling of blood and fluid will happen in the ankles. Right upper quadrant pain: Also caused by large ASD; has same symptoms and underlying causes as weight gain and ankle edema. Ascites: Ascite is known as abnormal buildup of fluid in spaces between abdomen lining and abdominal organs. Same symptoms and causes as weight, gain, ankle edema, and right upper quadrant pain. Less common symptoms Paroxysmal nocturnal dyspnea, orthopnea, and hemoptysis (sign of pulmonary venous congestion): this symptoms are less frequent in Lutembacher's syndrome and are more associated with MS and small ASD or patients who develop reverse Lutembacher's syndrome. This symptom is caused by mitral stenosis. Related disorders Eisenmenger syndrome Ventricular Septal Defect Mitral regurgitation Ebstein disease Causes Lutembacher is caused indirectly by heart damage or disorders. Lutembacher's syndrome is caused by either birth defects where the heart fails to close all holes in the walls between the atria or from an episode of rheumatic fever where damage is done to the heart valves such as the mitral valve and resultant in an opening of heart wall between atria. With Lutembacher's syndrome, a fetus or infant is usually seen to have a hole in their heart wall (interatrial) separating their right and left atria. Normally during fetal development, blood bypasses the lungs and is oxygenated from the placenta. Blood passes from the umbilical cord and flows into the left atrium through an opening called the foramen