Sunday, September 5, 2010

Post CABG arrythmias/AF

Following a CABG there are usually two peak times in the incidence of arrhythmia's. The first in the operating room and the second usually is between the second and fifth post-op days. The underlying problems of why there is usually arrhythmia's is still unclear. But many describe them due to the effects of circulating catecholamines, changes in the autonomic nervous system tone, changes in the electrolyte imbalance, myocardial ischemia or just irritation of the heart.

Other several factors may include flux changes of the electrolytes within in K+, MG+, CA+, and maybe Dig tox effects.

Atrial Fibrillation is the most common arrhythmia following cardiac surgery, the best management strategies is yet to be defined. Even if the patient has been on prophylactic Dig, beta blockers, transient A-Fib occurs in at least 25%-30%of patients after CABG.

New methods have been now utilized as FedMedic described. If the patient is hemodynamically stable some use of Verapamil (5mg SIVP) q every 5 minutes upt to 3-4 doses. Newer in the past 5-10 yrs is Dilitizem (Cardizem 0.25mg-0.35mg/kg bolus over 2 minutes). Esmolol (Brevibloc ) is Beta1 blocker, a newer med primarily used for SVT as well. The problem is sudden discontinuation can lead to increase . The dose is dysrhythmias usually 50 mcg/kg to 200 mcg/kg and one has to perform a "loading dose: first with a maintenance drip followed. Dosage needs to be recalculated if they are already on Beta blocker up to 50%. Some of the cardiologist I am in rotation with loves the stuff, and the other despises it.. so I have seen mix results, personally I have seen it abolish SVT in lieu of cardioversion. Professionally, have not seen it used that much for A-fib with RVR, but understand it is an alternative.

The pacemaker is newer device that has brought an alternative way for those with chronic A-fib, that is resistant to other therapy. One of the physicians father is one of the inventor of the bi-chamber pacer and as well experimental cutaneous plasty ablation that re-routes the pathway.

SVT, is also another post CABG side effect, as well as ventricular arrhythmias. Although new conduction defects may develop up to 45% of patients following cardiac surgery, the majority are usually transient and related to the use of cold cardioplegia, hypothermia, and electrolytes shifting.

Of course other dangers include P.E.'s , arterial spasms, myocardial ischemia. Almost all patients have a pericardial effusion. These effusions may develop into cardiac tamponade post-op and has to be considered in patients that of course have JVD, muffled heart tones, pulse paradoxus ( (Beck's Triad) and or hypotension.

The other problem that I did not realize was so prominent was mediastinitis, which occurs about within 2 weeks. the usually represent fever and purulent discharge from sternal wound.

Risk factors from this is usually from prolong cardiopulmonary bypass time, excessive bleeding, and poor cardiac output. Usually, the incidence of mediastinitis is increased with both the internal mammary arteries are used bilaterally for use of conduits. Many Doc's prefer to use only to use the left internal mammary artery, especially in geriatric, and diabetics, who may already have a wound healing problem.

Usually, one obtains wound cultures as well as blood cultures and seek specific growth. Staphylococcus aureus (Staph) is the usual culprit.

The most common medication are usually as described from airway goddess described. More common are angiotensin-converting enzyme (ACE) inhibitors
and anticoagulants such as Coumadin, or Plavix. The problem with ACE is they can cause problems on the glomerular capillary pressure as well the patient has already been through nephrotoxic drugs, radiocontrast med's (they glow in the dark) and cholesterol plaque med.'s this can screw up the kidneys and cause renal failure.

Even though these procedures are considered "routine" and occur daily nationwide, and over all most do not have "drastic" effects, Surgeon and EMS needs to be cautious aware of potential patients

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