Coronary flow and reactivity, but not arrhythmia vulnerability, are affected by cardioplegia during cardiopulmonary bypass in piglets

Relevance and Recommendations for the Application of Cardioplegic Solutions in Cardiopulmonary Bypass Surgery in Pigs

Cardioplegic solutions play a major role in cardiac surgery due to the fact that they create a silent operating field and protect the myocardium against ischemia and reperfusion injury. For studies on cardioplegic solutions, it is important to compare their effects and to have a valid platform for preclinical testing of new cardioplegic solutions and their additives. Due to the strong anatomical and physiological cardiovascular similarities between pigs and humans, porcine models are suitable for investigating the effects of cardioplegic solutions. This review provides an overview of the results of the application of cardioplegic solutions in adult or pediatric pig models over the past 25 years. The advantages, disadvantages, limitations, and refinement strategies of these models are discussed.

Review findings included diminished coronary flow reserve after surgery in children with congenital heart disease and inflammation

AIM

The aim of this review was to develop a deeper knowledge of the physiology of coronary blood flow and coronary flow reserve in young patients with congenital heart disease and inflammatory diseases.

METHODS

We searched for papers published in English on coronary blood flow and coronary flow reserve using the PubMed and Google search databases. This identified 42 papers extending back to 1976 and a book from 2008 (Davis et al. Microcirculation. Boston, MA: Elsevier, 2008: 161-284).

RESULTS

Our review showed that the implications of coronary blood flow and coronary flow reserve in paediatric patients with congenital heart disease and inflammatory diseases are still not fully understood. However, a key finding was that coronary flow reserve was diminished in patients with congenital heart disease and inflammation after surgery, with or without a cardiopulmonary bypass. Other findings discussed by this review relate to volume and pressure overload in acyanotic congenital heart disease, reduced myocardial perfusion and cyanotic congenital heart disease.

CONCLUSION

We still have much to discover about paediatric patients with congenital heart disease and inflammatory diseases. Understanding the pathophysiology of coronary blood flow could help the postoperative treatment of such patients.

The inflammatory state provokes sexual dimorphism in left ventricular and electrocardiographic effects of chronic cyclosporine in rats

Although cardiotoxicity has been recognized as an adverse effect of cyclosporine A (CSA), no information exists regarding sex specificity of CSA cardiotoxicity. We tested the hypothesis that left ventricular (LV) and electrocardiographic (ECG) effects of CSA and related inflammatory/histopathological derangements are sex related. CSA reduced the LV slope of end-systolic pressure volume relationship and increased isovolumic relaxation constant. These effects were more pronounced in male compared to female rats, suggesting LV systolic and diastolic dysfunction. ECG recordings showed elevated ST segments and increased QTc and T peak trend intervals in CSA-treated male rats, markers of LV ischemia and arrhythmogenesis. In female rats, CSA delayed AV conduction, as reflected by prolonged PR interval. Other sex-related effects for CSA included (i) increased blood cholesterol, and reduced rates of rise and fall in LV pressure and nuclear factor kappa B and angiotensin receptors type 1 expressions in male rats, and (ii) increased LV adiponectin in females. Histopatholgically, CSA caused vascular congestion, blood extravasation, and pyknotic or even absent nuclei in both sexes. In conclusion, rats exhibit sex-independent susceptibility to negative LV and histopathological influences of CSA. These effects become more intensified in male rats, perhaps on account of aggravated ischemic and inflammatory milieus.

Coronary flow dynamics in children after repair of Tetralogy of Fallot

OBJECTIVES

To assess the possible effect of a stiff right ventricle on the coronary flow (CF) in patients with post-operative Tetralogy of Fallot (TOF).

BACKGROUND

Right ventricular restrictive physiology i.e. forward flow during atrial contraction (RVRP), is characteristic to many patients with post-operative TOF.

METHODS

A total of 34 patients with TOF anatomically corrected through transatrial repair were included. Coronary flow parameters were registered with transthoracic Doppler echocardiography from posterior descending (PDCA) and left anterior descending (LAD) coronary arteries in the same patient in 24/34 (71%) patients. Twenty age-matched healthy children were used as controls. Cardiac magnetic resonance (CMR) imaging was used to detect myocardial fibrosis, RV volume, and RVRP.

RESULTS

The mean age at investigation was 10.2 ± 2.8 years. RV end diastolic and end systolic volumes indexed for BSA were larger in patients with RVRP (p=0.002 and 0.008 respectively). Peak flow velocity in diastole and flow velocity time integral was increased in patients compared to controls. They were increased in the LAD in patients with fibrosis of RV (n=11) compared to patients without fibrosis (n=9) (p=0.01 and 0.047 respectively). LAD coronary flow was especially increased in patients with RVRP (n=9) as compared with those without (n=11), (p=0.006).

CONCLUSIONS

Patients at mid-term followup after correction of TOF show increase of coronary flow. This increase is more pronounced in patients with fibrosis and RVRP of the RV.