Continuous monitoring of myocardial acid-base status during intermittent warm blood cardioplegia

Del Nido Cardioplegia in Coronary Artery Bypass Grafting Surgery: A safe, efficacious and economic alternative to St. Thomas solution; an experience from a developing nation

INTRODUCTION

del Nido cardioplegia is a newer solution getting popular worldwide, whereas in Nepal, St. Thomas cardioplegia solution is conventionally used. There is no national recommendation on cardioplegia solutions supported by evidences from Nepalese studies. This study aimed to evaluate and compare the efficacy of these solutions in Nepalese patients undergoing coronary artery bypass grafting.

METHODS

Patients undergoing coronary revascularization, from May 2018 to December 2019, were randomized into St. Thomas and del Nido groups based on the cardioplegia administered, with 45 patients in each group. Preoperative, intraoperative, and postoperative parameters and cost of cardioplegia preparation in the two groups were compared.

RESULTS

The cardiopulmonary bypass time (106.13 ± 24.65 minutes vs 107.62 ± 18.69 minutes, p = 0.02), aortic cross clamp time (66.22 ± 15.40 minutes vs 72.07 ± 12.23 minutes, p = 0.04), volume (1059.22 ± 100.30 ml vs 1526.67 ± 271.81 ml, p < 0.001) and number of cardioplegia doses (1.00 ± 0.00 vs 2.51 ± 0.66, p < 0.001) were significantly lower with del Nido cardioplegia. A lower CPK-MB at second post-operative (59.91 ± 31.62 vs 73.82 ± 37.25, p = 0.03) and a higher left ventricle ejection fraction at discharge (56.33 ± 8.94% vs 50.45 ± 8.55%, p < 0.001) was observed in del Nido group. There was one death in St. Thomas group. ICU and hospital stay were similar in both groups. St. Thomas solution was found to be costlier than del Nido solution (USD 5.40 ± 0.96 vs USD 3.50 ± 0.34, p < 0.001).

CONCLUSION

The del Nido cardioplegia was found to be efficacious, safe and more economical alternative to St. Thomas solution.

Using near-infrared spectroscopy myocardial oximetry to monitor myocardial oxygen balance in a swine model of cardiac surgery: a descriptive study

Monitoring of the adequacy of myocardial protection with cardioplegia is nearly non-existent in clinical cardiac surgical practice and instead relies on well-defined protocols for delivery of cardioplegia often resulting in inadequate protection. We hypothesized that Near Infrared Spectroscopy technology could be useful in the monitoring of the myocardial oxygen state by attaching the monitors to the epicardium in a porcine model of cardiac surgery. The experiments were conducted with 3 different protocols of 2 pigs each for a total of 6 pigs. The objective was to induce episodic, oxygen supply-demand mismatch. Methods for decreased supply included decreasing coronary blood flow, coronary blood hypoxemia, coronary occlusion, hypovolemia, and hypotension. Methods for increase demand included rapid ventricular pacing and the administration of isoproterenol. Changes in myocardial tissue oximetry were measured and this measurement was then correlated with blood hemoglobin saturations of oxygen from coronary sinus blood samples. We found that decreases in myocardial oxygen supply or increases in demand due to any of the various experimental conditions led to decreases in both myocardial tissue oximetry and hemoglobin oxygen saturation of coronary sinus blood with recovery when the conditions were returned to baseline. Correlation between myocardial tissue oximetry and hemoglobin oxygen saturation of coronary sinus blood was moderate to strong under all tested conditions. This may have translational applications as a monitor of adequacy of myocardial protection and the detection of coronary occlusion.

The predictive value of intraoperative transit-time flow measurement parameters for early graft failure in different target territories

BACKGROUND

Early graft failure can affect the short- and long-term outcomes of patients undergoing coronary bypass grafting surgery (CABG). The aim of our study was to explore the predictive value of transit-time flow measurement (TTFM) parameters for early graft failure (before discharge) after CABG in different coronary territories and calculate the TTFM cut-off values.

METHODS

We analyzed a total of 761 grafts (360 patients) that were evaluated by intraoperative TTFM and computed tomography angiography prior to discharge. Logistic model was established to detect the parameters of TTFM to predict early graft failure and receiver operating characteristic curve analysis was used to calculate the cut-off values.

RESULTS

The overall early graft failure was 3.5%. The results demonstrated that compared with off-pump CABG, mean graft flow volume was higher (28.0 vs 21.0 mL/min, p = 0.000), but pulse index (PI) (2.3 vs 2.5, p = 0.049) and diastolic flow fraction (DF) (68.0% vs 71.0%, p = 0.001) were lower in on-pump CABGs. DF (73.0% vs 65.5%, p = 0.000) of arterial grafts was higher than that of venous grafts. DF (72.0% vs 62.0%, p = 0.000) in left was higher than that in the right coronary artery territories. The results of multivariate logistic analysis showed that not only in the overall (OR 1.18, 95% CI 1.07-1.30, p = 0.001), but also the left (OR 1.21, 95% CI 1.03-1.41, p = 0.017) and right (OR 1.15, 95% CI 1.03-1.29, p = 0.017) coronary artery target territories, PI was a risk factor for early graft failure and the cut-off value was 3.4, 3.4, and 3.6, respectively. For grafts in left target territories, the results showed that DF (OR 0.94, 95% CI 0.91-0.97, p = 0.000) just in the univariate analysis was a risk factor that affected graft failure.

CONCLUSIONS

The overall early graft failure was about 3.5%. High PI value is a risk factor for early graft failure in not only overall grafts but in grafts of different target territories. DF might be more useful for the quality evaluation of grafts in left than in right target territories.

Influence of coronary territory on flow profiles of saphenous vein grafts

Background

Differing perfusion of the left and right ventricular coronary territory may influence flow-profiles of saphenous vein grafts (SVGs). We compared flow parameters, measured by transit-time flowmetry (TTFM), in left- and right-sided SVGs during coronary artery by-pass grafting (CABG).

Methods

Routine TTFM measurements were obtained in 167 SVGs to the left territory (55%) and 134 SVGs to the right territory (total of 301 SVGs in 207 patients). The four standard TTFM parameters, [mean graft flow (MGF), pulsatility index (PI), percentage diastolic filling (%DF), and percentage backward flow (%BF)] were compared. Differences in flow parameters were also examined according to surgical technique (on- vs. off-pump).

Results

No significant difference between coronary territories was found for MGF, PI and %BF. However, a higher %DF was noted in left-sided SVGs in the overall cohort as well as in the on-pump (both p < 0.001) and the off-pump cohorts (p = 0.07). Further, a significantly higher %BF was found in SVGs performed off-pump to the left territory (1.2 ± 2.5 vs. 2.3 ± 3.0, p = 0.023). In a multivariate regression analysis, anastomosing a SVG to the left territory was weakly associated with higher PI (OR = 0.36, p = 0.026) and strongly associated with higher %DF (OR = 5.1, p < 0.001). No significant association was found for MGF, PI, %DF or %BF in either the on-pump nor the off-pump cohorts.

Conclusions

Although statistically significant, the established differences in TTFM parameters between left- and right-sided vein grafts were small and unlikely to be of clinical relevance.

Comparison of del Nido cardioplegia and St. Thomas Hospital solution - two types of cardioplegia in adult cardiac surgery

INTRODUCTION

St. Thomas' cardioplegic solution No. 2 (ST), although most widely used in adult cardiac surgery, needs to be given at short intervals, causing additional myocardial injury.

AIM

To determine whether del Nido (DN) cardioplegia, with longer periods of arrest, provides equivalent myocardial protection as compared to ST.

MATERIAL AND METHODS

The study population comprised 100 patients who underwent elective coronary artery bypass grafting (CABG) or double valve replacement (DVR) surgery between January 2015 and January 2016. The patients were divided into two groups based on the type of cardioplegia administered during surgery: 1) intermittent ST (ST, n = 50) and 2) DN cardioplegia (DN, n = 50). We compared the aortic cross clamp (CC) and cardiopulmonary bypass (CPB) times, number of intra-operative DC shocks required, and postoperative changes in left ventricular ejection fraction (LVEF) in the two groups.

RESULTS

The aortic cross clamp and bypass times were shorter with DN (110.15 ±36.84 vs. 133.56 ±35.66 and 158.60 ±39.92 vs. 179.81 ±42.36 min respectively, p < 0.05). Fewer cardioplegia doses were required in the DN group vs. the ST group (1.38 ±0.59 vs. 4.15 ±1.26; p = 0.001), while a single cardioplegia dose was given to 35 DN patients (70%) vs. 0 ST patients (p < 0.001). Postoperative LVEF was better preserved in the DN group.

CONCLUSIONS

The use of DN leads to shorter cross clamp and CPB times, reduces cardioplegia dosage, and provides potentially better myocardial protection in terms of LVEF preservation, with a safety profile comparable to ST cardioplegia.

The Great Britain and Ireland perspective: current perfusion safety issues, preparing for the future

The Great Britain and Ireland (GBI) recommendations for standards of monitoring and alarms during cardio-pulmonary bypass (CPB) came into force in January 2004. While perfusion departments in Great Britain and Ireland should now have a good baseline level of safety, it is important that department-specific safety is also considered. Patient safety is paramount, but safety within our speciality must also take into account the protection of the perfusionists’ health and the protection of their careers. These different aspects of safety are fundamentally interrelated.

This paper focuses on the importance of careful assessment, implementation and documentation when a new component or technique is being introduced to the CPB circuit, even when the aim is to increase safety.

Knowledge of the civil justice system and the trends in medical negligence claims are an integral part of perfusionist safety. Perfusion in Great Britain and Ireland is rightly striving for professional recognition from the Health Professions Council (HPC). As we raise the profile of perfusion, we educate more people about the importance of our role and level of responsibility within the cardiac operating team. This will increase the potential for medical negligence claims to be directed specifically at our speciality. All these issues are discussed in detail.

Cold intermittent cardioplegia reduces the acidosis during prolonged cardiac surgery with cardiopulmonary bypass

The effect on acid-base balance efficacy of intermittent warm and cold blood cardioplegia (IWBC, ICBC) was assessed in 44 patients who underwent cardiac surgery with prolonged aortic cross clamping. With this purpose a customized multi sensor probe was inserted in the coronary sinus, and pH, PO(2), PCO(2) and temperature were continuously measured at 1 Hz sampling rate. The mean cross-clamping time was of 76 ± 26 min on 19 IWBC cases and of 80 ± 24 min on 14 ICBC cases. With IWBC perfusion, at the end of every ischemic period, the lowest pH and PO(2) progressively decreased and the maximal PCO(2) increased. During ICBC the minimum of pH and PO(2) and maximum of PCO2 at the end of different ischemic period during time were constant, also during long cross-clamping time. With IWBC, myocardial ischemia seemed not completely reversed by standardized reperfusions, as reflected by steady deterioration of PCO(2) and pH after each reperfusion.

Early systemic effects of hind limb ischemia-reperfusion on hemodynamics and acid–base balance in the rat

We investigated the systemic hemodynamic effects and the early arteriovenous acid-base changes after 2-h tourniquet ischemia on left hind limb in rats during the first hour of reperfusion. The right femoral artery and vein were prepared and catheterized for direct blood pressure monitoring and blood sampling. In ischemia-reperfusion group, 5 min before releasing the tourniquet and during the first hour of the reperfusion (5', 10', 15', 30', 45', and 60'), arterial and venous blood samples were taken in parallel with a sham operated control group. In the ischemia-reperfusion group venous pH continuously decreased during reperfusion and was significantly lower compared to control and base in the 60th min, while arterial pH remained almost unchanged. PCO2 and pO2 showed moderate signs of a parallel respiratory compensation. Mean arterial pressure decreased almost by 20%, heart rate slightly increased during reperfusion. Our data indicates that besides the general effects anesthesia, limb ischemia-reperfusion results in hemodynamic and acid-base changes during the first hour of reperfusion.

Transit time flow measurement in on-pump and off-pump coronary artery surgery

OBJECTIVE

Transit time flow measurement is frequently used during coronary artery bypass with and without cardiopulmonary bypass to detect graft dysfunction resulting from technical errors.

METHODS

Intraoperative transit time flow measurement measurements of 896 patients requiring surgery for double- or triple-vessel disease were reviewed retrospectively. Six-hundred and ninety-five patients were operated on-pump (Group A: coronary artery bypass with cardiopulmonary bypass), and 201 patients off-pump (Group B: coronary artery bypass without cardiopulmonary bypass). Transit time flow measurement measurements were analyzed for mean flow (mL/min). In total, measurements of 2247 grafts were analyzed.

RESULTS

Transit time flow measurement flows were lower in coronary artery bypass without cardiopulmonary bypass patients (left internal thoracic artery to left anterior descending artery: Group A, 37 [31, 40] mL/min vs Group B, 24 [20, 26] mL/min; saphenous vein graft to left anterior descending artery: Group A, 46.5 [40, 56] mL/min vs Group B, 21 [14, 57] mL/min. Troponin I release was reduced in the coronary artery bypass without cardiopulmonary bypass patients, with median values of 7.8 [7.0, 8.3] microg/L in Group A and 1.2 [0.9, 2.3] microg/L in Group B.

CONCLUSION

Evaluation of transit time flow measurement is valuable in determining coronary graft patency after coronary artery bypass with cardiopulmonary bypass and coronary artery bypass without cardiopulmonary bypass. Decreased troponin I release suggests a myocardial benefit of coronary artery bypass without cardiopulmonary bypass compared to coronary artery bypass with cardiopulmonary bypass, although the intraoperative transit time flow measurement flow measurements are markedly lower.