Diastolic dysfunction is a relatively new clinical diagnosis being made in patients where the observed echocardiographic findings are deemed to be consistent with abnormalities of left ventricular (LV) filling. Left ventricular filling is dependent on the complex interaction of three processes: LV relaxation, LV compliance, and left atrial (LA) contraction. 1 Left ventricular relaxation is an active process involving the uptake of Ca ?? into the sarcoplasmic reticulum by the sarcoendoplasmic reticulum Ca ?? ATPase pump and removal of Ca ?? from the cell by way of the sodium-calcium exchanger. Sarcoendoplasmic reticulum Ca ?? ATPase pump expression and activity is reduced in the cardiomyocyte (and diastolic function is altered) with the onset of senescence, hypertrophy, and heart failure. Left ventricular compliance is a measure of the relationship between LV volume and LV pressure development during LV filling (dV/dp). Left ventricular compliance is influenced by: 1) the presence of ventricular hypertrophy; 2) the functional state of the right ventricle (direct diastolic ventricular interaction), since both ventricles share the septum as a common wall; and 3) the properties of the pericardium. 2 Abnormal LV compliance is a feature of longstanding poorly-controlled hypertension, 3 right ventricular dysfunction, 4 and pericardial disease. 2 In the presence of abnormal LV relaxation and/or compliance, LA contraction assumes a key role in maintaining LV filling. Under physiological conditions in youthful individuals, atrial contraction contributes approximately 20% of the total filling volume of the LV; whereas, in patients with LV diastolic dysfunction, LA contraction may account for over 50% of LV volume at enddiastole. 1 Absence of LA contraction, as occurs with the development of atrial fibrillation, is a harbinger of heart failure and is a marker of an increased risk of premature death. 5 The occurrence of abnormal LV relaxation and compliance, as a consequence of hypertensive heart disease, is one of the most common determinants of LA enlargement, poor LA contractile function, and LA dysrhythmia development. 6