[Radionuclide ventriculography for evaluating left ventricular myocardial contractility in patients with implanted...

Area of Science:

• Cardiology
• Biomedical Engineering

Background:

• Complete atrioventricular block necessitates pacing for hemodynamic stability.
• Coronary heart disease (CHD) and idiopathic conduction disturbances present unique challenges for pacemaker optimization.

Purpose of the Study:

• To determine optimal pacemaker stimulation rates for patients with CHD and idiopathic conduction disturbances.
• To evaluate the impact of different pacing rates on left ventricular contractility and ejection dynamics.

Main Methods:

• Implantation of EKC-500 pacemakers in 30 patients (16 with CHD, 14 with idiopathic conduction disturbance).
• Equilibrium radionuclide ventriculography using a nuclear stethoscope at rest and during exercise.
• Assessment of left ventricular contractility and ejection parameters at various stimulation rates.

Main Results:

• Patients with idiopathic conduction disturbances demonstrated improved left ventricular contractility at all tested rates, with optimal values between 60-70 bpm.
• In CHD patients, 60 bpm was optimal at rest, but exercise at this rate deteriorated contractility. A rate of 80 bpm yielded slight improvement via accessory mechanisms.
• Peak ejection rate was most sensitive to myocardial dysfunction; mean ejection rate served as the basic contractility index.

Conclusions:

• Optimal pacemaker settings vary significantly between patients with idiopathic conduction disturbances and those with CHD.
• Pacemaker optimization using radionuclide ventriculography is crucial for maximizing cardiac function and patient outcomes.