Is blood cardioplegia superior to crystalloid cardioplegia?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether blood cardioplegia is clinically superior to crystalloid cardioplegia for myocardial protection. Altogether 501 papers were identified. We selected 22 papers that represented the best evidence to answer the question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. This is a difficult topic to review, as the techniques studied in the many trials performed vary widely. Factors which may vary include warm or cold blood cardioplegia, antegrade and retrograde administration, systemic hypothermia or normothermia, topical heart cooling, high and low potassium solutions, 'hot shots', warm induction, volume of cardioplegia, patient factors and bypass times. However, three papers stand out. The meta-analysis of 34 randomised trials by Prof Fremes (2006) found a significantly lower incidence of low output syndrome (LOS) and CK-MB release with blood cardioplegia. He found no differences in myocardial infarction or mortality. This meta-analysis was confounded, however, by the fact that he was unable to extract data on LOS and CK-MB from the two largest trials which contributed over half the patients in his paper and are significantly larger than all other studies. The first paper by Ovrum (2006) randomised 1440 patients to antegrade cold blood or crystalloid and found no clinical differences, and the second paper by Martin (1994) of 1001 patients compared warm blood to cold crystalloid but the study had to be stopped due to a high incidence of neurological events in the warm blood group. We reviewed a further 18 randomised trials reporting over 50 patients. Of these, 10 reported some statistically significant clinical outcomes in favour of blood cardioplegia and five reported statistically significant differences in enzyme release in favour of blood cardioplegia. A recent survey of UK practice found that 56% of surgeons use cold blood cardioplegia, 14% use warm blood cardioplegia, 14% use crystalloid cardioplegia, 21% use retrograde infusion and 16% do not use any cardioplegia. The papers presented in our review support most of these practices!     

Should amiodarone or lidocaine be given to patients who arrest after cardiac surgery and fail to cardiovert from ventricular fibrillation?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether the administration of amiodarone or lidocaine in patients with refractory VT/VF after cardiac surgery results in successful cardioversion. Altogether more than 434 papers were found using the reported search, from which 23 articles were used to answer the clinical question. No randomized trials have been found in which amiodarone was studied in patients with refractory VF/VT after cardiac surgery. Recommendations on the use of amiodarone in patients with refractory VF/VT in both European and American 2005 Guidelines on Resuscitation are mainly based on expert consensus and are supported by a few randomized trials in patients with out-of-hospital cardiac arrest. We would therefore recommend that amiodarone is the first line drug that should be used in patients with refractory ventricular arrhythmias after cardiac surgery that persist after three failed attempts at cardioversion. Lidocaine should only be used if amiodarone is not available or if its use is contraindicated. Amiodarone should be administered as an intravenous bolus of 300 mg after the third unsuccessful shock.     

What is the patency of the short saphenous vein when used for coronary artery bypass grafting?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was what the patency of the short saphenous vein is, when used for coronary artery bypass grafting. Altogether 347 papers were found using the reported search, of which nine represented the best evidence to answer the clinical question. The authors, journal, date and country of publication, patient group studied, study type, relevant outcomes and results of these papers are tabulated. We conclude that small reports give a two-year patency of 77% and a six-year patency of 65% and duplex studies show that the short saphenous vein may be from 2.8 mm to 4.2 mm in diameter. However, caution should be applied when considering these patency rates as they are derived from individual studies of <40 patients. The lesser saphenous vein may be considered as an alternative to brachial or cephalic vein in patients with unsuitable long saphenous vein, and unsuitable mammary, radial or gastroepiploic arteries.     

Should patients undergoing coronary artery bypass grafting with mild to moderate ischaemic mitral regurgitation also undergo mitral valve repair or replacement?

A best evidence topic in cardiac surgery was written according to a structured protocol. The question addressed was whether mitral valve repair at the time of coronary artery bypass grafting (CABG) in patients with coronary artery disease and mild to moderate mitral insufficiency improves short and long-term outcome. Altogether 465 papers were found using the reported search, of which 16 presented the best evidence to answer the clinical question. The author, journal, date and country of publication, patient group studied, study type, relevant outcomes, results, and study weaknesses of these papers are tabulated. We conclude that there is good evidence to suggest that moderate mitral regurgitation in patients undergoing isolated CABG adversely affects survival and mitral regurgitation does not reliably improve after CABG alone. Unfortunately, the evidence to support mitral valve repair at the time of CABG to improve long-term survival is still weak. On balance, patients with moderate ischaemic mitral regurgitation having CABG should have mitral repair at the same time, although the evidence to support this is weaker than one might like.     

Pulmonary thromboendarterectomy.

Pulmonary thromboendarterectomy (PTE) provides a curative alternative to the otherwise fatal condition of chronic thromboembolic pulmonary hypertension (CTEPH). However, the condition is under-diagnosed due to a lack of awareness. An acceptable operative mortality of around 10% and long-term survival exceeding medical therapy or transplantation makes PTE a favourable choice for the treatment of CTEPH. Outcome is further optimised if the disease is diagnosed early and patients referred to specialised centres. An increase in the number of surgical procedures will also contribute to lower the mortality associated with this condition.