Related Experiment Videos
The mechanism of hypotension following angiography
Insights
Hypotension after contrast media injection in angiography differs by procedure. Myocardial depression is key in coronary angiography, while peripheral vasodilation dominates aortic root injection hypotension.
Area of Science:
- Cardiovascular Physiology
- Diagnostic Imaging
Background:
- Hypotension following intracardiac contrast media injection is multifactorial.
- The primary cause (myocardial depression vs. peripheral vasodilation) in different angiography types remains unclear.
Purpose of the Study:
- To differentiate the mechanisms of hypotension induced by selective coronary angiography versus aortic root angiography.
Main Methods:
- Anesthetized dogs underwent either selective left coronary artery injection or aortic root injection of Renografin-76.
- Hemodynamic parameters including heart rate, arterial pressures, and left ventricular pressures (peak dp/dt, dp/dt-40) were continuously monitored.
Main Results:
- Selective coronary injection caused immediate hypotension linked to myocardial depression.
- Aortic root injection showed a biphasic blood pressure response, with initial depression followed by recovery, implicating peripheral vasodilation as the main cause of later hypotension.
- Left ventricular end-diastolic pressure increased in both procedures.
Conclusions:
- The mechanism of hypotension is dependent on the type of contrast angiography performed.
- Myocardial depression is primary in selective coronary angiography.
- Peripheral vasodilation is the likely primary mechanism in aortic root angiography-induced hypotension.
Abstract:
The hypotension observed following the intracardiac injection of contrast media is believed to be the result of myocardial depression, peripheral vasodilatation, or both. It is unclear which of these factors is primarily involved in different types of angiography. To assess this problem, Renografin-76 was injected into the aortic root of 15 anesthetized dogs (1 ml/kg) and into the left coronary artery (3-5 ml) in 18 dogs. The heart rate, the systolic and diastolic arterial pressures, left ventricular pressure, peak dp/dt and dp/dt-40 were monitored continuously until return to baseline. Following selective left coronary artery injection, both systolic and diastolic pressures decreased maximally at 5 seconds with parallel changes in peak dp/dt and dp/dt-40. Following the aortic root injection, the blood pressure response was biphasic, increasing at 5 seconds and decreasing maximally at 20 seconds. The corresponding changes in peak dp/dt and dp/dt-40 were initial depression at 5 seconds with quick return to baseline and increase above control at the time of maximal hypotension. The left ventricular end diastolic pressure rose maximally at 5 to 10 seconds for both coronary and aortic injections. The mechanism of hypotension, therefore, varies with the type of angiography. Myocardial depression appears to be a primary factor with selective coronary angiography. However, with aortic root injection, myocardial contractility, although initially depressed, is already improved at the time of maximal hypotension, and thus peripheral vasocilatation is probably the prime mechanism of the hypotension.