The limits of cardiac preservation with University of Wisconsin solution

Clinical assessment of prolonged myocardial preservation for patients with a severely dilated heart

BACKGROUND

The purpose of this study was to compare the myocardial protective effect of histidine-tryptophan-potassium and glucose-insulin-potassium cardioplegic solutions in patients with a dilated heart (left ventricular diastolic diameter > 55 mm, left ventricular systolic diameter > 45 mm) associated with prolonged cross-clamp time (longer than 200 minutes).

METHODS

We selected 20 patients with dilated hearts due to severe aortic regurgitation. Glucose-insulin-potassium cardioplegia was used in 11 patients and histidine-tryptophan-potassium cardioplegia was used in 9 patients.

RESULTS

After operation, the cardiac index was significantly increased in the histidine-tryptophan-potassium group (p < 0.05). Postoperative percent fractional shortening was 13.4% +/- 3.1% in the glucose-insulin-potassium group and 23.6% +/- 2.6% in the histidine-tryptophan-potassium group (p < 0.05). Creatine kinase levels were significantly lower in the histidine-tryptophan-potassium group than that in the glucose-insulin-potassium group (p < 0.05). The incidence of ventricular arrhythmia (higher than Lown's grade 2) was lower in the histidine-tryptophan-potassium group.

CONCLUSIONS

These data support the superiority of the histidine-tryptophan-potassium method over the glucose-insulin-potassium method for protection of the dilated heart during prolonged ischemia in open heart operations.

University of Wisconsin solution preserves myocardial calcium current response to isoproterenol in isolated canine ventricular myocytes

BACKGROUND

University of Wisconsin (UW) solution has been shown to be an effective solution for cold storage of various organs. This study was designed to evaluate the subcellular protective mechanism of UW solution during cardiac myocyte storage using patch-clamp techniques for the first time as a tool for the detection of myocyte viability.

METHODS AND RESULTS

The protective effects of UW solution on the preservation of dihydropyridine-sensitive Ca2+ channel current response to catecholamine were evaluated in canine cardiac ventricular cells by measurement of single channel open probability. Single ventricular myocytes were isolated and stored in UW solution, in Stanford (SF) solution, or in St Thomas' (ST) solution at 4 degrees C for 2, 6, 12, and 24 hours, and after each storage period, recordings were made of cell-attached single Ca2+ channel currents. When 0.1 mumol/L isoproterenol was applied, percent mean open probability of the Ca2+ channel tested in freshly isolated cells was 167 +/- 4% (n = 24) of controls (100%). The response was decrescent with increased duration of the hypothermic storage and was only 130 +/- 12% (n = 4) after 24 hours of storage in SF solution and 135 +/- 9% (n = 7) in ST solution. However, it was significantly highly preserved as much as 165 +/- 9% (n = 6) in UW solution. Ca2+ channel kinetics and channel conductance were not changed after up to 24 hours of hypothermic storage.

CONCLUSIONS

Hypothermic storage of canine cardiac myocytes in UW solution preserved beta-adrenergic response, which suggests that UW solution during cold storage preserved high-energy phosphates in myocytes that are responsible for Ca2+ channel phosphorylations.

Cardiac storage with University of Wisconsin solution and a nucleoside-transport blocker

Findings from previous investigations conducted at this institution and others have suggested that University of Wisconsin solution (UWS) is preferable for the prolonged hypothermic storage of hearts before transplantation. The benefit seen with UWS may in part be related to the inclusion of adenosine (5 mmol/L) in the UWS. To investigate whether further manipulations of adenosine metabolism might enhance myocardial protection, studies were initially conducted using cultured myocytes, followed by confirmatory experiments using isolated rat hearts. Cultured human ventricular myocytes (7 to 8 dishes/group) were stored for 12 hours at 0 degrees C in unmodified UWS or UWS supplemented with increasing concentrations (1 to 100 mumol/L) of the nucleoside-transport blocker p-nitrobenzylthioinosine. The adenosine triphosphate concentrations were found to be enhanced with nucleoside-transport inhibition, with the best results achieved with the 1- and 3-mumol/L groups (control, 3.37 +/- 0.41 nmol/micrograms DNA; UWS, 2.89 +/- 1.31 nmol/micrograms DNA; 1 mumol/L, 5.91 +/- 3.23 nmol/micrograms DNA; 3 mumol/L, 7.86 +/- 3.45 nmol/micrograms DNA; p < 0.05 versus control or UWS group). Isolated rodent hearts from Sprague-Dawley rats were prepared on a Langendorff apparatus with an intraventricular balloon and subsequently stored for 8 hours at 0 degrees C in unmodified UWS (13 hearts/group) or UWS supplemented with 1 or 3 mumol/L of p-nitrobenzylthioinosine (9 to 10 hearts/group).(ABSTRACT TRUNCATED AT 250 WORDS)