Cardiac Assist Devices PDF

Cardiac Assist Devices Melody Vetica, DNP, CRNA  ECMO is a device that can support respiratory and circulatory systems of patients during situations extreme stress Extracorporeal It has the similar function of...

Cardiac Assist Devices Melody Vetica, DNP, CRNA  ECMO is a device that can support respiratory and circulatory systems of patients during situations extreme stress Extracorporeal It has the similar function of CPB Membrane Oxygenator Two types: Venovenous and Venoarterial Temporary measure lasting days to weeks  Venovenous: VV Indicated for respiratory failure Improves gas exchange along with protective ventilation Single double lumen catheter into IJ with tip in IVC; blood drains from IVC and SVC into oxygenator and is reinfused in second lumen that is pointed toward the tricuspid valve Double femoral cannula: tip near the RA and reinfused to opposite femoral vein  Venoarterial: VA Provides both gas exchange and hemodynamic support Blood drained from vein and reinfused into an artery under pressure Uses: Cardiogenic shock Failure to wean from CPB Allograft failure after heart or lung transplant Pulmonary embolism Sepsis Peripartum cardiomyopathy Hybrid: venoarterial and venous Residual native cardiac function pumps deoxygenated blood into the ascending aorta; affects cerebral profusion Add second reperfusion limb into the IJ If peripheral cannulation does not prove adequate support, then central cannulation is necessary; similar to CPB RA drainage with aorta or pulmonary venous repurfussion  Retrograde blood flow from reinfused blood Causes increased can cause increased myocardia oxygen left ventricular demand afterload; LVEDP Left Percutaneous or ventricular surgical placement of a left ventricular Can lead to statis and venting ‘vent’ will divert some blood back to the thrombosis ECMO circuit Also helps reduce upper body hypoxemia Venovenous ECMO: Bridge to recovery for respiratory failure ARDS most common reason Primary graft dysfunction post transplant ( usually need VA) Acute hypercapnic respiratory failure Can prevent mechanical ventilation Minimize risk of VALI Minimize risk of pneumonia Give aerosolized medications Early mobilization Bridge to Transplant No destination device, reserved pts. on transplant list  Cardiogenic shock Acute MI and fulminant myocarditis (best VA ECMO: outcome) Temporary measure if cannot wean from CPB Bridge to Primary graft failure recovery for cardiac Extracorporeal CPR Better for ‘younger’ age? failure Decompensated PHTN  Bridge to Ventricular Assist Device or transplant Duration 1-2 weeks Assess neurological and other organ systems recovery When unclear recovery possibility, ends up a bridge to decision Management Protective ventilation Anticoagulants No standards set Before insertion-ACT 180-200 secs Heparin combined with ECMO leads to thrombocytopenia (ie, HIT) If VV flow rates >3L/min, may not need anticoagulation (VV has lower risk of embolization) Weaning is different for VV and VA VV Incremental decrease in sweep flow Blood flow reduced very cautiously May stop sweep flow for 30 minutes to assess respiratory work and function VA Minimize vasopressors and inotropes Blood flow reduced ( less than 2L/min to avoid thrombosis) Decrease in sweep flow can cause hypoxemia with R to L shunt If needed can turn into a VV for continued respiratory suppoet  Hematologic Heparin Induced Thrombocytopenia: HIT Acquired von Willebrand disease Complications DIC Infection Limb ischemia Vascular perforation Other Considerations Cost Ethical Need good EBP guidelines DNR No end device for respiratory failure Intra-aortic balloon pump: IABP One of the simplest and most commonly used assist devices Easily done at the bedside using femoral artery Many are put in by interventional cardiologists in the cath lab if there is a large proximal lesion to support patient for open heart Size based on patient height- 20-50 ml balloons  Basic operation of IABP Placed in the descending aorta Allows intrinsic cardiac ejection with synchronized counter pulsation Inflated at onset of diastole Displaces proximal from the balloon toward the coronary arteries Thereby increases diastolic BP perfusion At onset of systole balloon deflates; creates a ‘vacuum’ to reduce afterload-decreases O2 demand and some increase in CO  Tip placed at the junction of aortic arch and descending aorta (use TEE to determine position) Synchronizes with the QRS complex or dicrotic notch on a- line wave form Usually set at 1:2 ratio Stroke volume of balloon Determined by patient size Typically set at 50-60% of patient’s ideal stroke volume Balloon filling time decreased with tachycardia Contraindications for placement AI During balloon inflation, increase pressure on aortic valve causes increased insufficiency Results in LV distention Sepsis Severe vascular disease  Not usually required first few hours after Management of CPB anticoagulation If post open heart, no anticoagulation until chest tube drainage less then 100-150ml/h When heparinized, get ACT q 4-6 hours If 1:1 ratio, may not heparinize Complications Vascular (most common) *high risk with vascular disease Limb ischemia Compartment syndrome Mesenteric infarction Aorta perforation or dissection Infection Neurologic Thrombocytopenia Device malfunction  Left Ventricular Assist Device (most common): LVAD Right Ventricular Assist Device: Ventricular RVAD Assist Devices Both ventricles : BiVAD  With an LVAD, blood is drawn out of the left Difference ventricle, into the pump, then into the aorta, and on to the body. (Oxygenated blood) between RVAD and With an RVAD, blood is drawn out of the right LVAD ventricle, into the pump, then into the pulmonary artery, and on to the lungs to pick up oxygen. (Unoxygenated blood) VADs are classified as: Short or long term Intra, extra, or Location paracorporeal Continuous Type of flow Pulsatile Axial (newer)  Types of therapy Bridge to transplant On list for transplant and have failed inotrope or conventional therapy Destination therapy Do not meet the criteria for transplant 2- year survival rate 58% CMS approved  Continuous flow Advantages Smaller, easier to implant Less dissection Less blood loss Reduced infection rate Disadvantages Types of Do not have valves; need minimum flow to prevent stasis flow Some devices cause von Willebrand’s disease Minimal arterial pulse, even with full flow Intraoperative considerations Standard monitors and TEE Arterial line in large artery Monitor cerebral oxygenation Most VADs are continuous flow TEE to assess Aortic valve competency LV thrombus Patent foramen ovale RV function Many patients will also have a pacer or ICD Large bore peripheral and central IV Continue inotrope infusions Prone to exaggerated BP drop on induction Due to increased sympathetic tone Preemptive norepinephrine Avoid nitrous (many will have PHTN) Many have RV failure For example, cisatricurium may be the muscle relaxant of choice  CPB without cardiac arrest Either RA or LA cannulation for short term Surgical LV apex used for long term Technique use Initiation of support device Ventilation established Heart gradually filled When only LVAD, there can be pulmonary obstruction caused by PVR which increases the chance of RV dysfunction A mild AI can become significant (needs aortic valve repaired before implantation) Intracardiac shunt: PFO Present in 20% of population (asymptomatic) When LA an LV are ‘unloaded’, pressure in LA is greater than RA therefore opening foramen ovale and causing a R to L shunt Inotrope support: dobutamine, milrinone, and epinephrine Vasopressin is a good choice for BP control because it does not constrict pulmonary vasculature ** Implantation of an isolated RVAD is rare (usually BiVAD)  Hemorrhage Thromboembolism Infection Device malfunction Complications Management of VAD in non-cardiac surgery Decern type of device Continuous flow devices are pre-load dependent and after-load sensitive Position of patient can affect device function Clotting status Warfarin changed to heparin Prepare for blood component therapy Consider NIRS technology to monitor cerebral perfusion (continuous flow) TAH