Adjunct Cardiac Devices Flashcards
What is an Intra-aortic balloon pump (IABP) and what is it used for?
- It is used in patients with cardiogenic shock
- The goal of the device is to is to increase coronary artery perfusion and decrease oxygen consumption.
- Is the single most widely used circulatory assist device
What are the 7 indications for using an IABP?
- Preinfarction angina refractory to pharmacological therapy – awaiting further evaluation and determination of next therapy
- AMI resulting in cardiogenic shock
- Refractory ventricular arrhythmias related to ischemia
- Severe mitral valve regurgitation as result of MI
- Severe VSD as result of MI
- Before or after heart surgery – for persistent low cardiac output
- Low cardiac output states – can be placed prophylactically in patients waiting for CABG to prevent abrupt deterioration. Also indicated in patients with severe decompensated CHF
What are the contraindications to using an IABP?
Absolute:
- Aortic aneurysm or dissection
- Bypass grafting from the aorta to peripheral vessels
- Aortic insufficiency – significant (more than mild AR) or prosthetic aortic valve
- Uncontrolled sepsis
- Severe untreated bilateral peripheral vascular disease that cannot be treated with stenting
Relative:
- Peripheral or central atherosclerosis – cholesterol embolization is rare but can result in limb loss
- Bleeding disorders, uncontrolled
- History of embolic event
- Ethical considerations including advanced age, severe LV dysfunction and multi system failure. The benefits of the IABP against QOL issues must be considered
What are the therapeutic effects of an IABP?
- Improvement of coronary artery perfusion, reduction of afterload, improved perfusion to organs
- The IABP inflates during diastole, when the AV is closed. This displaces blood backward increasing perfusion to the coronary arteries. It also displaces blood forward increasing perfusion to the vital organs
- The balloon deflates just before contraction or systole, when the AV opens. This sudden deflation reduces the pressure in the aorta decreasing afterload. Myocardial oxygen demand is reduced
What are some complications associated with an IABP?
- Lower extremity ischemia due to occlusion of the femoral artery by the catheter itself or by emboli
- Vascular laceration requiring surgical repair
- Major hemorrhage – CVA is rare however
- Displacement of the catheter due to patient movement
- Balloon perforation
- Infection
- Destruction of RBCs due to hemolysis caused by the pump
- Failure to wean
- Sepsis – is uncommon unless the IABP is left in place > 7 days
What are the weaning parameters for a patient with an IABP?
Hemodynamic support with an IABP should be continued as long as the benefits outweigh the risks. It should be removed as soon as the patient shows improvement (criteria listed below) or sooner for complications. The patient should be hemodynamically stable as evidenced by:
- Cardiac index of 2.5 L/minute or greater
- MAP 70 mmHg or higher
- Normal pulmonary capillary wedge pressure of 6-12 mmHg
- Absence of chest pain
- Normal perfusion on physical exam
- Weaning methods include decreasing the volume in the balloon with each inflation by 25% per reduction OR decrease the frequency of inflation (from every cardiac sequence to every other, to every third)
What is a pacemaker?
Electronic devices that deliver stimuli (impulses) to the cardiac muscle in an effort to maintain adequate heart rate and cardiac output when the patient’s own intrinsic pacemaker becomes insufficient
What are the indications for using a pacemaker?
- Symptomatic bradycardia (off medications) with symptoms of cerebral hypoperfusion
- Acquired complete or high grade AV heart block
- Sick sinus syndrome (atrial fibrillation with 5 second pauses)
- Atrial tachycardias
- Ventricular tachycardia
What are the complications associated with pacemakers?
- Failure to capture - no QRS is noted after the spike
- Failure to pace – no pacemaker activity when indicated by settings
- Failure to sense – random spikes occur during the patients cardiac cycle
What is an automatic internal cardioverter/defibrillator (AICD)?
Electronic device implanted to automatically intervene with life threatening arrhythmias. ICDs have been shown to decrease mortality compared to antiarrhythmic therapy in survivors of VF or hemodynamically unstable patients with VT. VF is a known common cause of sudden cardiac death (SCD) but is sometimes preceded by monomorphic or polymorphic VT. Studies have shown that the only effective approach for terminating VF is an electrical shock. This led to the development of the implantable ICD and approval by the FDA in 1985.
What are the indications for using an automatic internal cardioverter/defibrillator (AICD)?
Primary Indication:
- for SCD includes patients with CAD and an LVEF < 35% . Also, patients with known dilated or other cardiomyopathy with LVEF < 35%. These are set by Centers for Medicare and Medicaid Services (CMS). Also, patients with life threatening VT that has not responded to medical management are an indication for this therapy.
Secondary Indication:
- Patients with prior sustained VT, VF or resuscitated SCD thought to be due to VF/VT
In what situations are Automatic internal cardioverter/defibrillators (AICD) not recommended?
- Patients with VT due to a completely reversible disorder in the absence of structural heart disease. This would include patients with electrolyte imbalances, drugs or trauma
- Patients that do not have a reasonable expectation of survival with an acceptable functional status for at least 1 year
- Patients with incessant VT or VF in whom other therapies such as catheter ablation are being considered
- Patients with severe psychiatric illnesses that may be aggravated by the implantation of the device
- Patients with NYHA Class IV heart failure that is refractory to optimal medical management who are not candidates for cardiac transplantation or CRT implant
- Patients with syncope without inducible ventricular tachyarrhythmias and without structural heart disease
The special pacing mode of a pacemaker that can terminate ventricular tachycardia is_____?
Antitachycardia pacing
A patient has a VVI pacemaker in place. What does the first letter of a pacemaker code indicate?
The first letter refers to the chamber(s) paced
Examples: Atrial (A), Ventricular (V) or Dual (D).
A patient has a VVI pacemaker in place. What does the second letter of a pacemaker code indicate?
The second letter refers to the chamber(s) sensed. (A,V,D)
