Appleton CP, Galloway JM, Gonzalez MS, Gaballa M, Basnight MA Estimation of left ventricular filling pressures using two-dimensional and Doppler echocardiography in adult patients with cardiac disease. Additional value of analyzing left atrial size, left atrial ejection fraction and the difference in duration of pulmonary venous and mitral flow velocity at atrial contraction. J Am Coll Cardiol. 1993 Dec;22(7):1972-82.
Hsiao SH, Huang WC, Lin KL, Chiou KR, Kuo FY, Lin SK, Cheng CC Left atrial distensibility and left ventricular filling pressure in acute versus chronic severe mitral regurgitation. Am J Cardiol. 2010 Mar 1;105(5):709-15. doi: 10.1016/j.amjcard.2009.10.05
Simek CL, Feldman MD, Haber HL, Wu CC, Jayaweera AR, Kaul S Relationship between left ventricular wall thickness and left atrial size: comparison with other measures of diastolic function. J Am Soc Echocardiogr. 1995 Jan-Feb;8(1):37-47.
Studies on Assessment of Left Atrial Distensibility to Predict Late Prognosis in Consecutive Patients Received Echocardiographic Examination
Interventional studies are often prospective and are specifically tailored to evaluate direct impacts of treatment or preventive measures on disease.
Observational studies are often retrospective and are used to assess potential causation in exposure-outcome relationships and therefore influence preventive methods.
Expanded access is a means by which manufacturers make investigational new drugs available, under certain circumstances, to treat a patient(s) with a serious disease or condition who cannot participate in a controlled clinical trial.
Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.
Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.
