Decreased postsystolic contraction during warm water immersion. A patient with left bundle branch block demonstrates a different pattern of the left atrioventricular plane recording on land compared with water. 2A. Standing position on land, AVPD 3.5 mm, post-systolic contraction 6.1 mm. 2B. Standing position in warm water, AVPD 8.2 mm, post-systolic contraction 1.4 mm. 1) Start of LV contraction; 2) end of LV contraction; 3) start of early diastolic filling; 4) end of diastolic filling, beginning of diastasis; 5) end of diastasis, beginning of atrial contraction; 6) end of atrial contraction. 7) start of next contraction. AVPD: atrioventricular plane, SC: systolic contraction, PSC: post-systolic contraction.