Figure 3. Normal cardiac function after loss of TBX5 in the VCS.

(A and B) Cardiac function, assessed by M-mode echocardiography, of Tbx5^fl/fl controls (A) and Tbx5^minKCreERT2 littermates (B) administered tamoxifen at 6–7 weeks of age and studied 4–5 weeks later in sinus rhythm. No functional difference between mutant and control mice was detected. (C) A Tbx5^minKCreERT2 animal with episodic spontaneous ventricular tachycardia demonstrated rapid recovery of ventricular function during sinus beats (asterisks) that followed tachycardic episodes.