In this chapter we discuss three non-coronary complications: hypotension, radiation skin injury, and contrast-induced acute kidney injury (CI-AKI).
Continuous careful monitoring of the pressure and electrocardiographic tracing is critical for enhancing the safety of PCI ( Section 2.2 ). Awareness of the differential diagnostic algorithm if hypotension occurs during angiography or PCI can facilitate rapid decision making and initiation of corrective actions.
The appearance of low blood pressure on hemodynamic monitoring does not necessarily mean that the patient’s systemic blood pressure is low, as “hypotension” could be due to technical issues ( Fig. 28.1 ). Therefore, when hypotension occurs, it should be immediately assessed to determine whether the patient is truly hypotensive or not. If the patient’s systemic blood pressure is indeed low, the differential diagnosis should be immediately considered to allow prompt diagnosis and treatment.
(Systemic pressure is normal, but appears low on the arterial pressure tracing)
Hemostatic valve of the Y-connector is open.
Connection between catheter and pressure transducer is open or has air in the line.
Pressure dampening. This is common, especially in patients with ostial coronary lesions and with use of large guide catheters, such as 8 French. Dampening can be masked when side hole guide catheters are used, hence the latter should never be used to engage the left main coronary artery (with the exception of ostial left main CTOs), as they can mask ischemia and lead to patient hemodynamic collapse.
Catheter obstruction by air, thrombus, or contrast (contrast can cause pressure dampening, especially in 4 and 5 French catheters). The catheter should be aspirated. If aspiration fails, the catheter should be removed without performing any injection.
Bulky equipment within the catheter.
There are three major causes of true hypotension: hypovolemia, cardiac failure, and peripheral vasodilation ( Fig. 28.1 ). If the cause of hypotension is not immediately apparent, right heart catheterization can be very useful for determining the cause of hypotension.
Hypovolemia is most commonly caused by bleeding. Inspection of the access sites may reveal a hematoma. Fluoroscopy of the bladder may demonstrate the “dented bladder” sign ( Fig. 29.3 ) that suggests retroperitoneal hematoma.
Cardiac output is the product of (stroke volume)×(heart rate). Decreased stroke volume may be due to: (1) left or right ventricular dysfunction, which is most commonly caused by ischemia; (2) valvular abnormalities, such as acute valvular regurgitation; and (3) pericardial tamponade.
Amplatz catheters (and deeply curved EBU catheters) may push the aortic cusp open and cause acute aortic regurgitation ( Fig. 28.2 ); simple guide catheter repositioning can immediately correct the hypotension.
Both tachyarrhythmias and bradyarrhythmias can also reduce cardiac output.
Peripheral vasodilation may be due to a vasovagal reaction, a systemic anaphylactic reaction, or medication administration, such as nitroglycerin (especially if the patient had been recently exposed to phosphodiesterase 5 inhibitors) or verapamil (intracoronary or intraarterial for preventing radial spasm).
Preventing false hypotension can be accomplished using meticulous techniques:
Careful assessment and verification of all connections.
Meticulous care in clearing the catheter after insertion.
Avoiding deep catheter engagement causing dampening.
Preventing true hypotension can be achieved via careful planning of the procedure and attention to each step, as follows:
Careful arterial access technique and use of radial access, as well as avoiding excessive anticoagulation can decrease the risk of bleeding.
Adequate pre-procedural hydration.
Considering prophylactic hemodynamic support in high-risk patients undergoing PCI, as described in Chapter 14 : Hemodynamic Support.
Preventing prolonged coronary artery occlusion will minimize ischemia.
Avoiding perforations and the resultant tamponade.
Adequate premedication for patients with contrast allergy will decrease the risk of anaphylactic shock ( Section 3.3 ).
Early diagnosis and correction of tachyarrhythmias and bradyarrhythmias.
Adequate sedation and hydration may minimize the risk of a vasovagal reaction.
Avoiding excessive doses of nitroglycerin and other vasodilators.
Immediate and complete treatment of the underlying cause is best for correcting hypotension, but may not always be feasible, for example, in patients who develop acute vessel closure that cannot be recanalized. Therefore, concomitant implementation of measures that can increase the systemic blood pressure and maintain systemic perfusion is often needed.
Maintain systemic perfusion
While treating the underlying cause of hypotension, administration of vasopressors and inotropes and in some patients initiation of mechanical circulatory support ( Chapter 14 : Hemodynamic Support) may be necessary. If the patient develops cardiac arrest, cardiopulmonary resuscitation is performed (ideally using an automated system, such as the Lucas system), followed by veno-arterial extracorporeal membrane oxygenation (VA-ECMO) initiation if the patient does not promptly recover.
Treat underlying cause
Hypovolemia : Normal saline administration and blood transfusion in case of bleeding. If bleeding is due to an arterial access complication, a balloon should be inflated to stop active bleeding, followed by endovascular or surgical repair, as described in Chapter 29 – Vascular Access Complications.
Myocardial dysfunction : This is usually caused by ischemia and can be improved with coronary revascularization and in some cases with mechanical circulatory support.
Valvular disease : Although acute mitral or aortic regurgitation may benefit from vasodilator administration, they are often poorly tolerated requiring urgent or emergent surgery. Acute mechanical circulatory support may also improve hemodynamics, such as an intraaortic balloon pump for acute mitral regurgitation.
Pericardial disease : Tamponade is treated with pericardiocentesis. If the patient has myocardial rupture (usually in the setting of acute myocardial infarction) emergency surgery is needed.
Arrhythmias : Arrhythmias occurring in the cardiac catheterization laboratory are usually due to ischemia, hence treatment of ischemia will improve or correct them. Arrhythmias often occur after reperfusion (post-reperfusion arrhythmias). Bradycardia and atrioventricular block is often caused by medication administration, such as adenosine ( Section 3.2.4 ), however the duration of action of adenosine is very short.
Peripheral vasodilation : Epinephrine for anaphylactic shock and fluid administration.
Radiation skin injury
Excessive radiation dose can result in deterministic complications (e.g., radiation skin injury), but can also lead to stochastic complications (e.g., cancer or birth defects) . Significant technological developments can help reduce radiation dose .
Deterministic radiation effects, such as skin injury and cataracts, correlate directly with the air kerma dose to a particular skin area ( Fig. 28.3 ) .
The following AK dose thresholds are important to remember :
<5 Gray : Below this threshold skin injury is unlikely to occur.
5–10 Gray : Skin injury is possible.
10–15 Gray : Skin injury is likely, requiring physicist assessment of the case.
>15 Gray : This is considered a sentinel event by the Joint Commission for Hospital Accreditation and requires reporting to the regulatory authorities in the U.S.
Preventing radiation skin injury can be achieved by limiting the overall radiation dose and by rotating the image intensifier to distribute the radiation dose to various skin areas ( Fig. 28.4 ).
Reducing patient (and operator) radiation dose can be achieved both before and after the procedure:
Before the procedure
Careful planning of the procedure can prevent unnecessary steps, facilitate procedural success and minimize contrast and radiation dose. Careful procedural planning applies not only to complex procedures, such as chronic total occlusion interventions , but every procedure. For example, carefully studying the location of aorto-coronary bypass grafts on previous angiograms can expedite bypass graft engagement. Catheterization in very obese patients should be performed with newer X-ray systems.
Newer X-ray machines achieve satisfactory image quality with lower radiation dose .
This is an add-on device to the X-ray system that allows the operator to identify a part of the screen to view in full resolution, while reducing radiation dose rate to the other parts of the screen, resulting in lower (but still adequate) image resolution in those areas and ≈75% radiation dose reduction.
Zero Gravity (reduces operator dose only)
The Zero Gravity ceiling-suspended lead (Biotronik) not only provides radiation protection to the operator, but also obviates the need for wearing lead and the associated orthopedic injuries.
Robotic PCI (reduces operator dose only)
Robotic PCI (CorPath, Corindus) allows near elimination of operator radiation dose , but is currently available only at a few centers.
The EggNest-XR System (Egg Medical) includes a series of shields that reduce scatter radiation.
During the procedure
Do not use radiation unless absolutely necessary
No pedal “lag time”
The “heavy foot” syndrome is defined as using X-ray when it is not needed, for example, when the operator is not looking at the screen! A “lag time” in releasing the pedal is common, especially in early stages of training, and should be a major focus for improvement.
Use balloon and wire markers
When advancing equipment through the guide catheter, use the balloon, wire, and stent shaft markers to determine if the device is close to the tip of the guide catheter at which time fluoroscopy is needed. Knowing the length of the guide catheter is critical, since using the more proximal marker in 90 cm guide catheters may result in the device exiting the guide catheter before the marker reaches the Y-connector.
Use trapping technique for equipment exchanges
The trapping technique ( Section 8.9.1 ) allows secure equipment exchanges while minimizing use of X-ray.
Cineangiography exposes the patient to ≈10× higher dose compared to fluoroscopy and is not reflected in the fluoroscopy time. The “image store” or “fluoro save” function, is available in most modern X-ray equipment ( Fig. 28.5 ) and should be used instead of cine to document balloon and stent inflations.