Value of purinic compounds in assessing sinus node dysfunction in man: a new diagnostic method.

Area of Science:

• Cardiology
• Pharmacology

Background:

• Sick sinus syndrome (SSS) diagnosis can be challenging, particularly for latent forms.
• Pharmacological tests are explored to aid in SSS diagnosis.

Purpose of the Study:

• To investigate if striadyne (STR) has a quantitatively different inhibitory effect on pathological sinus nodes compared to normal ones.
• To determine the utility of STR as a pharmacological test for diagnosing SSS.

Main Methods:

• 55 patients were divided into normal, SSS (flagrant and latent), and excess vagotonia groups.
• 30 mg of STR was injected intravenously after prophylactic temporary pacemaker insertion.
• Surface and intracavitary ECGs were recorded, evaluating sinus cycle (SC) parameters before and after STR administration.

Main Results:

• STR caused initial slowing followed by acceleration of sinus rate in all patients.
• Severe sinus cycle lengthening was observed in SSS patients (max SC 2500-11880 ms) compared to moderate lengthening in normal and vagotonia groups.
• Abnormal responses to STR were detected in 100% of flagrant SSS and 85.7% of latent SSS patients, with high statistical significance (P < 0.001).

Conclusions:

• The study demonstrates a significant quantitative difference in STR's effect on SSS sinus nodes.
• STR shows promise as a pharmacological test for diagnosing SSS, with abnormal responses observed in most SSS patients.
• Prophylactic ventricular pacing catheter insertion is recommended when using STR for SSS diagnosis.