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Coronary vasomotor tone: determinants and effect on coronary angioplasty
1George Hyman Research Building, Room 117, 108 Irving Street, N.W., Washington, D.C., 20010, USA. drott@starpower.net.
Insights
Coronary artery diameter increases during angioplasty due to resting vasomotor tone, often leading to undersized balloon selection. This study quantifies the increase and identifies factors influencing it, improving procedural outcomes.
Area of Science:
- Cardiology
- Interventional Cardiology
- Medical Imaging
Background:
- Coronary artery reference diameters increase during percutaneous transluminal coronary angioplasty (PTCA).
- Balloon selection often relies on pre-procedure diagnostic angiography, which may not reflect the true diameter due to resting vasomotor tone.
- Undersized balloon selection can lead to suboptimal angioplasty results.
Purpose of the Study:
- To quantify coronary artery vasodilatation over baseline angiography.
- To assess the impact of this vasodilatation on balloon size selection during PTCA.
- To identify clinical and treatment variables contributing to resting vasomotor tone.
Main Methods:
- Quantitative coronary angiography (QCA) was employed to measure coronary artery diameters.
- Analysis of pre-PTCA clinical and treatment variables to determine their influence on resting vasomotor tone.
Main Results:
- Post-PTCA reference diameters significantly increased compared to baseline (proximal: 13.6%, distal: 24.8%).
- Initial balloon diameter was smaller than the post-PTCA proximal segment by an average of 12.6%.
- Age < 65 years and pre-PTCA beta-blocker use were associated with increased baseline vasomotor tone.
Conclusions:
- Routine diagnostic angiography underestimates true coronary artery diameter.
- Resting vasomotor tone causes an approximate 13% increase in coronary reference segment diameter during successful PTCA.
- Underestimation necessitated a larger balloon in 16.5% of cases, highlighting the need for accurate diameter assessment.
Background:
Coronary artery reference diameters increase during coronary angioplasty (PTCA). However, in clinical practice, balloon selection is often based on a preceding diagnostic coronary angiogram. It is common to find that the initially selected balloon is undersized due to resting vasomotor tone. This may contribute to a suboptimal angioplasty result.
Methods:
Quantitative coronary angiography (QCA) was used to determine the magnitude of coronary artery vasodilatation over baseline angiography and its impact on balloon size choice. Pre-PTCA clinical and treatment variables were analyzed for their potential contribution to resting vasomotor tone.
Results:
QCA of reference coronary diameters was performed in a group of 103 patients undergoing PTCA. Post PTCA proximal and distal reference diameters significantly increased over baseline. The average increase of the proximal segment was 0.368 mm (13.6%) p < 0. 001 and of the distal segment 0.567 mm (24.8%) p < 0.001. The initial nominal balloon diameter was smaller than the post PTCA proximal segment by an average of 0.34 mm (12.6%) p < 0.001. Of the clinical and treatment variables examined age < 65 years and pre-PTCA beta blocker use, significantly affected baseline vasomotor tone p < 0.05.
Conclusions:
Routine diagnostic angiography underestimates the true diameter of the coronary artery. Due to baseline vasomotor tone, coronary reference segments can be expected to increase approximately 13% in diameter during successful PTCA. Patients under 65 years of age and those using beta-blockers may have a significantly increased baseline vasomotor tone. Underestimation of coronary artery diameter based on initial angiography necessitated a second, larger balloon in 16.5% of cases.
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