In vivo transthoracic echocardiography. Representative echocardiograms of 6 week old PHD2^+/+;Cre-ER (A) and PHD2 flox/flox;Cre-ER (B) mice after Tamoxifen treatment as in Figure 4A,B. Short axis views (left panels) show evidence of left ventricular dilatation in PHD2 flox/flox mice. Representative M-mode views (right panels), in which a cross section of the short axis view is monitored over time, shows dilatation as well a depressed left ventricular function. Inactivation of PHD2 did not affect heart rate (C) or wall thickness (D), but increased end diastolic left ventricular diameter (E) and decreased fractional shortening (F). *P < .05; **P < .01. Error bars indicate 1 SD.