MedGen

Right bundle branch block (RBBB) represents an abnormality in the intraventricular electrical conduction system of the human heart, generating enlarged QRS and modified vectors on the electrocardiogram (ECG). Incomplete RBBB (IRBBB) is defined by (i) QRS duration between 110 and 120 ms in adults; (ii) rsr, rsR, or rSR in leads V1 or V2. The R or r deflection is usually wider than the initial R wave. In a minority of patients, a wide and often notched R wave pattern may be seen in leads V1 and/or V2; (iii) S wave of greater duration than R wave or greater than 40 ms in leads I and V6 in adults; and (iv) Normal R peak time in leads V5 and V6 but greater than 50 ms in lead V1. The first 3 criteria should be present to make the diagnosis. When a pure dominant R wave with or without a notch is present in V1, criterion 4 should be satisfied. [from HPO]

An electrocardiographic finding, in the absence of left ventricular hypertrophy (LVH) and left bundle branch block pattern on ECG, of either a) new (or presumed new) ST elevation at the J point in two contiguous leads with the following cut-points: greater than or equal to 0.1 mV in all leads other than leads V2-V3 where the following cut points apply: greater than or equal to 0.2 mV in men age greater than or equal to 40 years, greater than or equal to 0.25 mV in men age greater than 40 years, or greater than or equal to 0.15 mV in women; or b) new (or presumed new) horizontal or down-sloping ST depression greater than or equal to 0.05 mV in two contiguous leads, and/or T wave inversion greater than or equal to 0.1 mV in two contiguous leads with a prominent R wave, or R/S ratio greater than 1. (Thygesen K, Alpert JS, Jaffe AS, et al.: the Writing Group on behalf of the Joint ESC/ACCF/AHA/WHF Task Force for the Universal Definition of Myocardial Infarction. J Am Coll Cardiol 60(16):1-18, 2012) [from NCI]

A purine nucleotide analogue antibiotic isolated from the bacterium Streptomyces antibioticus. Also known as 2''-deoxycoformycin, pentostatin binds to and inhibits adenine deaminase (ADA), an enzyme essential to purine metabolism; ADA activity is greatest in cells of the lymphoid system with T-cells having higher activity than B-cells and T-cell malignancies higher ADA activity than B-cell malignancies. Pentostatin inhibition of ADA appears to result in elevated intracellular levels of dATP which may block DNA synthesis through the inhibition of ribonucleotide reductase. This agent may also inhibit RNA synthesis and may selectively deplete CD26+ lymphocytes. (NCI04) [from NCI]