Adenosine and lidocaine: A new concept in nondepolarizing surgical myocardial arrest, protection, and preservation
Depolarizing potassium cardioplegia has been increasingly linked to left ventricular dysfunction, arrhythmia, and microvascular damage. We tested a new polarizing normokalemic cardioplegic solution employing adenosine and lidocaine as the arresting, protecting, and preserving cardioprotective combination. Adenosine hyperpolarizes the myocyte by A1 receptor activation, and lidocaine blocks the sodium fast channels.Methods
Isolated perfused rat hearts were switched from the working mode to the Langendorff (nonworking) mode and arrested for 30 minutes, 2 hours, or 4 hours with 200 μmol/L adenosine and 500 μmol/L lidocaine in Krebs-Henseleit buffer (10 mmol/L glucose, pH 7.7, at 37°C) or modified St Thomas' Hospital solution no. 2, both delivered at 70 mm Hg and 37°C (arrest temperature 22°C to 35°C).Results
Adenosine and lidocaine hearts achieved faster mechanical arrest in (25 ± 2 seconds, n = 23) compared with St Thomas' Hospital solution hearts (70 ± 5 seconds, n = 24; P = .001). After 30 minutes of arrest, both groups developed comparable aortic flow at ∼5 minutes of reperfusion. After 2 and 4 hours of arrest (cardioplegic solution delivered every 20 minutes for 2 minutes at 37°C), only 50% (4 of 8) and 14% (1 of 7) of St Thomas' Hospital solution hearts recovered aortic flow, respectively. All adenosine and lidocaine hearts arrested for 2 hours (n = 7) and 4 hours (n = 9) recovered 70% to 80% of their prearrest aortic flows. Similarly, heart rate, systolic pressures, and rate-pressure products recovered to 85% to 100% and coronary flows recovered to 70% to 80% of prearrest values. Coronary vascular resistance during delivery of cardioplegic solution was significantly lower (P < .05) after 2 and 4 hours in hearts arrested with adenosine and lidocaine cardioplegic solution compared with hearts arrested with St Thomas' Hospital solution.Conclusions
We conclude that adenosine and lidocaine polarizing cardioplegic solution confers superior cardiac protection during arrest and recovery compared with hyperkalemic depolarizing St Thomas' Hospital cardioplegic solution.