[Left ventricular hemodynamics in patients with sick sinus syndrome: analysis by 99mTc-RBC cardiac pool scintigraphy with forward and backward multiple gated method (FBMG)].

The left ventricular (LV) systolic and diastolic functions in 31 patients with sick sinus syndrome (types I and II) were analyzed using LV time activity curves obtained by a 99mTc-RBC cardiac pool scintigraphy-forward and backward multiple gated study (FBMG) and compared with those in controls. On A-V sequential pacing (rate, 70 bpm; A-V delay, 150 msec), LV-peak ejection rate (PER) and peak filling rate (PFR) were significantly decreased compared to those in normal controls. As pacing rate was increased, PFR decreased significantly in patients in whom PER was decreased. The etiology of disturbed LV systolic and diastolic functions in patients with sick sinus syndrome remains unknown. No patient had significant organic coronary artery disease or other cardiac disorder. On the other hand, the frequency of vasospastic angina was higher in this group than in the controls. We suspect that sick sinus syndrome and vasospastic angina probably share a common pathophysiology. In patients with sick sinus syndrome, LV systolic and diastolic functions are impaired at rest and during A-V sequential pacing.