6.2 Cardiac Emergencies (MI, CHF, Arrhythmia, Tamponade, Shock)

Cardiac Emergencies in the Cath Lab

The ARRT CI outline's Patient Care 1.H.2 list is a crash-cart syllabus: myocardial infarction, congestive heart failure, cardiac arrhythmias, vasovagal response, hypotensive and hypertensive episodes, shock (cardiogenic, hypovolemic, septic), cardiac tamponade, flash pulmonary edema, respiratory arrest, and anaphylaxis. Anaphylaxis is treated as in 6.1 — stop the injection, oxygen, physician-directed epinephrine, fluids, airway — and is not re-taught here. This section is about recognizing the same falling blood pressure when the cause is the myocardium, the pericardium, the volume tank, or the airway.

Quick Answer: Pads on, crash cart open, suction working, times documented. Vasovagal is bradycardia plus hypotension after pain. Tamponade after perforation is hypotension with equalized diastolic pressures and right-ventricular collapse — treat with pericardiocentesis. Ventricular fibrillation (VF) during a right coronary injection is defibrillated.

Myocardial infarction and no-reflow

The patient may already be a STEMI activation. The CI-specific emergency is new injury current that starts after you are on the table: dissection from a guide catheter or wire, acute closure, no-reflow or slow-flow after balloon or stent, or embolization of thrombus. New ST elevation, a new bundle-branch block, chest pressure, and a falling arterial pressure are ischemia until the operator says otherwise. Announce the lead group and the blood pressure in closed loop. Do not warehouse the finding until a convenient cine run.

Treatment is mechanical and pharmacologic in the coronary: wiring, balloon, stent, aspiration thrombectomy, and drugs such as intracoronary nitroprusside, nicardipine, or a glycoprotein IIb/IIIa inhibitor as the operator chooses. The technologist's job is images, activated clotting time, contrast tally, and keeping defibrillation pads already on the chest so VF is a shock, not a scavenger hunt.

Congestive heart failure and flash pulmonary edema

Congestive heart failure (CHF) in the lab is high left-ventricular filling pressure meeting extra volume and extra contrast. Patients with low ejection fraction, severe aortic stenosis, ischemic mitral regurgitation, or already wet lungs decompensate when a ventriculogram, a long PCI, or a bag of saline is added.

Flash pulmonary edema is the sudden form: pink frothy sputum, collapsing SpO2, crackles, and a patient who cannot lie flat, often minutes after a contrast or volume load. Sit the patient up if the sheaths allow, apply high-flow oxygen or noninvasive positive pressure if available, stop unnecessary volume, and support blood pressure. The operator may use nitroglycerin or nitroprusside for afterload, a loop diuretic, and, if the patient is crashing, intubation and mechanical circulatory support. Another left ventriculogram is not the treatment.

Cardiac arrhythmias

VF or pulseless ventricular tachycardia during right coronary artery (RCA) injection is a classic, exam-ready event: the injection opacifies the artery, the ST segments jump, and the arterial line becomes a VF squiggle. Call VF, confirm unresponsiveness, and defibrillate. Resume CPR if a pulse does not return. Atropine is not the VF drug.

Bradyarrhythmias cluster with RCA work (the sinoatrial and atrioventricular nodal arteries) and with vasovagal stimulation: sinus arrest, high-grade atrioventricular block. Have atropine drawn and a temporary pacing wire or balloon-tipped pacer in reach. Atrial fibrillation with a rapid ventricular response after a catheter in the right atrium is treated by the operator with rate control or cardioversion if unstable. Pulseless electrical activity after perforation is tamponade until proven otherwise — organized electrical activity without a pulse is not fine VF.

Vasovagal response; hypotensive and hypertensive episodes

Vasovagal: bradycardia plus hypotension after sheath insertion, a full bladder, pain, or anxiety. The patient is diaphoretic and nauseated, often without rash or wheeze. Stop the painful stimulus, give fluids, give atropine as ordered, and elevate the legs if the airway is safe. This is not anaphylaxis and not cardiogenic shock.

Hypotension without bradycardia needs a cause: ischemia, tamponade, bleeding, anaphylaxis, oversedation, or vasodilators. Treat the cause; a blind fluid bolus into a crashing left ventricle can produce flash edema.

Hypertensive episodes after pain, restraint, or a catecholamine are real. Confirm the reading, treat pain, and use a physician-directed vasodilator only for true hypertensive emergency — end-organ threat, aortic work, or a freshly implanted device that cannot tolerate the afterload. Do not chase every 170 mm Hg systolic with a bolus during a STEMI if the patient is otherwise stable.

Shock: cardiogenic, hypovolemic, septic

Cardiogenic shock is pump failure: cold, wet or gray, high filling pressures, low cardiac output, ongoing ischemia or a mechanical complication such as ventricular septal rupture or papillary-muscle rupture. Pressors (norepinephrine commonly first), inotropes, and mechanical circulatory support — intra-aortic balloon pump (IABP) or a transvalvular pump such as Impella, conceptually — plus reperfusion. The CI technologist prepares the device table, helium or purge fluid, and documentation of insertion time.

Hypovolemic shock is an empty tank: access-site or retroperitoneal bleeding, gastrointestinal bleed on dual antiplatelet therapy, or over-diuresis. Falling hematocrit, tachycardia, and a collapsing arterial line. Fluids, blood, reverse anticoagulation as directed, and stop the bleed (section 6.3).

Septic shock is uncommon at the first stick but appears with infected devices, delayed closure, or the febrile patient who arrives from another unit. Warm (early) or cold (late) shock, fever, and a wide pulse pressure early. Cultures, source control, and vasopressors are physician-directed; the technologist's job is to recognize that this hypotension is not vasovagal.

Cardiac tamponade

Wire perforation, a distal balloon rupture, or a covered-stent attempt that still leaks can fill the pericardium. Hallmarks: hypotension, jugular distention, pulsus paradoxus, equalization of diastolic pressures (right atrial, pulmonary capillary wedge, and left-ventricular end-diastolic pressures crowding together), and right-ventricular diastolic collapse on echocardiography or intracardiac echocardiography (ICE). Electrical alternans is late and not required.

Treatment is pericardiocentesis, volume while the needle goes in, and reversal of heparin with protamine as the operator orders if the coronary is not mid-stent. A covered stent or prolonged balloon tamponade treats the hole; the pericardial drain treats the filling. Do not give a pure vasodilator for this blood pressure.

Respiratory arrest and the technologist's role

Respiratory arrest may follow oversedation, flash edema, anaphylaxis, or a post-ictal state. Open the airway, suction, bag-valve mask with oxygen, and call for intubation. The CI technologist does not wander looking for a bag-valve mask that should already be on the cart.

Before every case: defibrillation pads on (or immediately available on a chest that was already clipped), crash cart unexpired, suction tested, oxygen flowing, reversal agents and emergency drugs known, and a plan for who documents times — collapse, first shock, epinephrine, return of spontaneous circulation. During the event, one voice, closed-loop, and a written timeline. After the event, the record is part of the care.

Scenario and traps

An RCA injection produces VF. Shock first. A distal wire perforation produces hypotension with equalized pressures and ICE collapse — drain the pericardium; atropine will not fill it. A sheath stick produces a slow heart rate and a sweaty patient without ST change — vasovagal. Pink froth after a 40 mL ventriculogram in severe aortic stenosis — flash edema, not more pictures.

Traps: treating tamponade as vasovagal because both have low blood pressure. Treating VF with atropine. Treating anaphylaxis with only diphenhydramine (6.1). Installing an Impella for hypovolemic shock from an unrecognized retroperitoneal bleed.