Optimal myocardial preservation with an acalcemic crystalloid cardioplegic solution

The effect of the calcium and oxygen contents of a hyperkalemic glucose-containing cardioplegic solution on myocardial preservation was examined in the isolated working rat heart. The cardioplegic solution was delivered at 4 degrees C every 15 minutes during 2 hours of arrest, maintaining a myocardial temperature of 8 degrees +/- 2 degrees C. Hearts were reperfused in the Langendorff mode for 15 minutes and then resumed the working mode for a further 30 minutes. Groups of hearts were given the oxygenated cardioplegic solution containing an ionized calcium concentration of 0, 0.25, 0.75, or 1.25 mmol/L or the same solution nitrogenated to reduce the oxygen content and containing 0 or 0.75 mmol ionized calcium per liter. The myocardial adenosine triphosphate concentrations at the end of arrest in these six groups of hearts were 15.6 +/- 1.2, 9.5 +/- 0.5, 8.2 +/- 1.1, 4.9 +/- 1.8, 10.1 +/- 2.0, and 1.6 +/- 0.4 nmol/mg dry weight, respectively. At 5 minutes of working reperfusion, the percentages of prearrest aortic flow were 80 +/- 2, 62 +/- 4, 33 +/- 6, 37 +/- 5, 48 +/- 7 and 46 +/- 8, respectively. The differences among the groups in adenosine triphosphate concentrations and in functional recovery diminished during reperfusion. In hearts given the hypoxic calcium-containing solution, there was a marked increase in coronary vascular resistance during the administration of successive doses of cardioplegic solution, which was rapidly reversible upon reperfusion. These data indicate that hearts given the acalcemic oxygenated solution had better adenosine triphosphate preservation during arrest and better functional recovery than hearts in any other group. Addition of calcium to the oxygenated cardioplegic solution decreased adenosine triphosphate preservation and functional recovery. Oxygenation of the acalcemic solution increased adenosine triphosphate preservation and functional recovery. The lowest adenosine triphosphate levels at end arrest were observed in hearts given the hypoxic calcium-containing solution. In the setting of hypothermia and multidose administration, the addition of calcium to a cardioplegic solution resulted in increased energy depletion during arrest and depressed recovery.     

Functional and histologic changes in vein grafts exposed to crystalloid potassium cardioplegic solution

A canine external jugular vein to iliac artery interposition model was devised to evaluate the potential deleterious effects of cold potassium cardioplegic solution exposure to saphenous vein grafts during aortocoronary bypass procedures. The right jugular vein was harvested from 11 animals and halved, one segment being perfused with 1 liter of normal saline solution (NS) at 4 degrees C over a period of 31.7 +/- 2.5 min at a perfusion pressure of 50.5 +/- 2.6 mm Hg, and the other segment perfused with 1 liter of crystalloid potassium cardioplegic solution (CP) at 4 degrees C over a period of 24.8 +/- 3.2 min at a perfusion pressure of 53.0 +/- 1.5 mm Hg. The measured differences in the perfusion times and pressures were not significant at P less than 0.05. The grafts were then interposed into the iliac artery systems of their respective animals, and transgraft pressure gradients were measured by direct needle puncture technique and found to be 12.6 +/- 5.9 mm Hg for the CP-treated grafts and 19.9 +/- 9.6 mm Hg for the NS-treated grafts. At the time of graft harvest 7.4 +/- 0.23 months later transgraft pressure gradients were again measured and found to be 2.5 +/- 1.8 mm Hg for the CP-treated and 2.9 +/- 1.7 mm Hg for the NS-treated grafts.(ABSTRACT TRUNCATED AT 250 WORDS)     

The addition of glutathione (YM737) to a crystalloid cardioplegic solution enhances myocardial protection

The effectiveness of a glutathione preparation, YM737, as a free radical scavenger when added to hypothermic (4°C) crystalloid cardioplegic solution was evaluated in this study. Rabbit hearts were preserved for 3 h in cardioplegic arrest by infusing 20 ml crystalloid cardioplegic solution initially, with additional 10-ml boluses administered every 30 min, while maintaining a myocardial temperature of 10°C. They were then reperfused with Krebs-Henseleit bicarbonate buffer at 37°C in a perfusion circuit for 60 min. The hearts were divided into two groups of six: One in which crystalloid cardioplegic solution was perfused (group 1); and one in which crystalloid cardioplegic solution containing YM737 1 mg/ml was perfused (group 2). The postischemic developed pressure (mmHg) in group 2 was significantly greater than that in group 1 after 60 min of reperfusion, being 44.8 ± 8.4 versus 87.8 ± 5.2 in groups 1 and 2, respectively (P < 0.01). Moreover, group 2 exhibited significantly lower postischemic left ventricular compliance after 60 min than group 1 (P < 0.01) and a significantly higher postischemic peak LV dp/dt (mmHg/sec) after 60 min of reperfusion, being 925 ± 213 versus 1,550 ± 111 in groups 1 and 2, respectively (P < 0.05). Based on the comparisons of postischemic hemodynamics it was concluded that the addition of glutathione to crystalloid cardioplegic solution does in fact enhance myocardial protection.     

Role played by oxygen in myocardial protection with crystalloid cardioplegic solution

To evaluate the importance of the oxygen dissolved in crystalloid cardioplegic solution, the protective effects of oxygenated glucose-insulin-potassium cardioplegic solution (O2-GIK) (oxygen tension greater than 600 mm Hg) on the isolated working guinea pig heart were compared with those of deoxygenated (N2-GIK) (oxygen tension less than 10 mm Hg) and aerated GIK solution (GIK) (oxygen tension = 140 to 160 mm Hg). Hearts were subjected to 180 minutes of ischemia with intermittent infusions (every 30 minutes) of cold cardioplegic solution, followed by 30 minutes of normothermic reperfusion. The O2-GIK solution tended to maintain high-energy phosphates at higher levels during ischemia, and resulted in the best recovery of cardiac function. Though not as effective as O2-GIK, GIK solution produced protective effects; N2-GIK solution failed to exert such effects. These results strongly suggest that the protective effects of crystalloid cardioplegic solution are due primarily to the oxygen dissolved in it; anaerobic metabolism or washout of the metabolites plays a minor part.     

Improved myocardial recovery after cardioplegic arrest with an oxygenated crystalloid solution

Possible enhancement of myocardial protection by oxygenation of a crystalloid cardioplegic solution was evaluated in a three-part study. In Part I, canine hearts underwent ischemia followed by heterogeneous cardioplegic arrest for 45 to 60 minutes. Oxygenation led to improved recovery in the left anterior descending region (47% versus 86% recovery, p less than 0.05) (15 minutes of ischemia) and in the circumflex region (9.5% versus 52% recovery, p less than 0.05) (30 minutes of ischemia). Part II was a blind prospective randomized study in 12 patients. It examined creatine kinase, myoglobin, and lactate as well as coronary sinus flow, oxygen consumption, and cardiac work 1 hour after aortic cross-clamping during atrial and during ventricular pacing. No significant difference was demonstrable between control and oxygenated solutions. In Part III, 57 coronary bypass patients were protected with a nonoxygenated solution while 94 patients received an identical oxygenated solution. Twelve-hour creatine kinase levels were similar in the nonoxygenated (9.5 +/- 16 IU, +/- standard deviation) and oxygenated (11 +/- 22 IU) groups if the cross-clamp interval was 28 minutes or less. In patients subjected to longer than 28 minutes of arrest, the 12 hour creatine kinase MB levels were more than twice as high in the nonoxygenated group (26.5 +/- 26 IU) compared to the oxygenated group (9.9 +/- 14 IU, p less than 0.05). In this canine model of heterogeneous cardioplegia and in the routine conduct of coronary bypass operations, oxygenated crystalloid cardioplegia is superior to an identical nonoxygenated solution.     

The effect of adding mannitol or albumin to a crystalloid cardioplegic solution: a prospective, randomized clinical study

To determine if the myocardial protection afforded by a cold crystalloid potassium cardioplegic solution could be improved by the addition of either mannitol or albumin, a prospective clinical study was undertaken in which 58 patients undergoing elective aortocoronary bypass were randomized to one of three groups. Each group featured a different cardioplegic solution. The solutions were a standard potassium crystalloid solution, a solution containing mannitol sufficient to raise the osmolality by 20 to 30 mOsm, and a solution containing 5% albumin. Preoperative, intraoperative, and postoperative evaluation included serial measurements of ejection fraction, myocardial-specific isoenzyme, and hemodynamic indexes of performance. Electrocardiographic evaluation for perioperative myocardial infarction and the need for postoperative inotropic and mechanical support were also included. No differences were found among the groups. Therefore, although the use of mannitol or albumin has been shown to be beneficial in an experimental setting, superiority of either additive could not be demonstrated clinically.     

A clinical comparative study between crystalloid and blood-based St Thomas' hospital cardioplegic solution.

OBJECTIVE: Myocardial protection with blood cardioplegia during cardiac surgery is increasingly preferred, but few studies have compared the protective effects of crystalloid cardioplegia to the same solution with blood as the only variable. This clinical study compared the protective effects of crystalloid or blood-based St. Thomas' Hospital cardioplegic solution No. 1. METHODS: Fifty higher risk patients undergoing elective coronary artery bypass surgery, with an ejection fraction less than 40%, were randomly allocated to receive cold (4 degrees C) intermittent crystalloid St. Thomas' No. 1 cardioplegia (n = 25), or a similar blood-based solution (n = 25) with a haematocrit of 10-12%. We determined (1) peri-operative and post-operative arrhythmias, (2) left and right ventricular function (24 h) using the thermodilution technique, (3) left ventricular high-energy phosphate content sampled before ischaemia, the end of ischaemia and the end of bypass. RESULTS: Pre-operative haemodynamic data, aortic cross-clamp and bypass times were similar in both groups of patients; there was no mortality. At the end of ischaemia there were no differences in ATP content between groups but creatine phosphate was maintained at a significantly (P < 0.007) higher level in the blood-based St. Thomas' cardioplegia group than the crystalloid St. Thomas' cardioplegia group (20+/-2 (SE) vs. 13+/-1 micromol/g dry wt, respectively). Return to spontaneous sinus rhythm was significantly (P = 0.002) increased in the blood-based St. Thomas' cardioplegia group (96%) compared to the crystalloid St. Thomas' cardioplegia group (60%). Early post-operative ventricular dysfunction occurred in both groups, but normal LV function (stroke work index) recovered significantly (P = 0.043) more rapidly (by 2 h) in the blood-based St. Thomas' cardioplegia group of patients. CONCLUSIONS: In a higher risk (EF < 40%) group of patients undergoing elective cardiac surgery, addition of blood to an established crystalloid cardioplegic solution significantly enhanced myocardial protection by reducing arrhythmias, improving rate of recovery of function and maintaining myocardial high-energy phosphate content during ischaemia.     

A flexible system for combined retrograde and antegrade delivery of blood or crystalloid cardioplegic solution

A flexible but simple cardioplegic delivery system has been designed that offers the advantages of alternating antegrade and retrograde delivery or blood and crystalloid (Plegisol? solution) cardioplegia to optimize myocardial preservation. Initial antegrade delivery of crystalloid cardioplegic solution achieves rapid cardiac arrest while subsequent retrograde delivery with blood cardioplegia improves myocardial protection due to uniform distribution of the solution. Occasionally, temporary transferral from blood to crystalloid is indicated to clarify the surgical field. This system is designed to allow the repeated rapid switching from crystalloid to blood cardioplegia or vice versa using the antegrade or retrograde routes.     

Myocardial protection with Hamburg oxygenated crystalloid cardioplegic solution for multiple coronary bypass and multivalvular replacement

We evaluated myocardial protection with Hamburg oxygenated crystalloid cardioplegic solution in a double study. Part I was a prospective metabolic study, measuring myocardial adenosine triphosphate (ATP) and creatine phosphate (CP) contents before and after ischemia in 30 coronary bypass (CABG) patients. During ischemia, CP levels decreased significantly, whereas ATP did not. After 10 minute of reperfusion, mean ATP contents were 90% of preischemic values and CP levels increased to 85% of preischemic values. Spontaneous myocardial defibrillation was seen in 93.3% of patients. Part II included evaluation of early postischemic myocardial function in 228 patients, 48 with multiple valve replacement (MUVR) and 180 with CABG. Spontaneous myocardial defibrillation was seen in 90.3%. Cardiac index, measured before and 1 and 12 hours after surgery, increased significantly in the postischemic period (from 1.95 +/- 0.9 to 2.5 +/- 0.7 l/min m2 in MUVR, p 0.04; from 2.2 +/- 0.6 to 2.7 +/- 0.7 l/min/m2 in CABG, p 0.01). Myocardial infarction frequency was 3% among CABG patients, and unrelated to the number of distal anastomosis or to aortic cross-clamp time. Early postoperative mortality was 6.2% for MUVR and 0.5% for CABG. Thus, oxygenated cardioplegia with Hamburg solution preserves high-energy phosphate compounds and prevents ischemic injury, with excellent short-term clinical results.     

An asanguineous reperfusion solution. An effective adjunct to cardioplegic protection in high-risk valve operations

The protection afforded by cardioplegia during elective ischemic arrest can be partly compromised by a reperfusion injury, which may impede the recovery of cardiac function. We previously showed experimentally that this postischemic damage could be largely avoided by an appropriate crystalloid reperfusate. The present study was thus undertaken to assess the effects of this "reperfusion solution" clinically. One hundred twelve patients undergoing valve replacement with the aid of hypothermic cardioplegia (K+ 12 mEq, Mg2+ 26 mEq) were prospectively divided in two groups: Group I (n = 49) received an unmodified blood reperfusate. In Group II (n = 63), 1 L of the reperfusion solution was delivered just prior to removal of the aortic clamp. The formulation of the reperfusion solution adhered to the following principles: (1) maintenance of cardioplegia (K+ = 15 mEq), (2) replenishment of Ca2+ stores (Ca2+ = 2.5 mEq), (3) substrate provision (glutamate = 2,942 gm), (4) buffering (pH = 7.70 at 28 degrees C), and (5) hyperosmolarity (370 mOsm). The two groups were matched for preoperative data except for a higher incidence of isolated aortic valve replacement (p = 0.01) in Group II. Also, the cross-clamp time (mean +/- standard error of the mean) was longer in Group II (94 +/- 4 minutes versus 63 +/- 4 minutes, p less than 10(-6]. The reperfusion solution was found to increase both the rate and extent of postischemic functional recovery, as evidenced by (1) a lower proportion of catecholamine-supported patients 48 hours after operation (9/63 [14.28%] versus 16/49 [32.6%] in the control group [p less than 0.03]) and (2) a lower amount (gamma/kg/min) of dobutamine required to achieve stable hemodynamics (11 +/- 1 versus 26 +/- 6 in the control group [p less than 0.03]). A similar recovery pattern was noted in the high-risk subgroup of patients with mitral valve disease. Further, serial postoperative hemodynamic measurements were performed in 31 randomly selected patients (10 control and 21 reperfused). Although the reperfused patients were found to be at higher risk because of lower preoperative cardiac indices and longer cross-clamp times, they consistently achieved better postoperative hemodynamics with a lower incidence of catecholamine support. This hemodynamic improvement was particularly reflected by a higher left ventricular stroke work index throughout the postoperative course, the difference being significant 6 hours and 12 hours postoperatively.(ABSTRACT TRUNCATED AT 400 WORDS)     

Endothelial cell damage following crystalloid cardioplegic solution infusion. Scanning electron microscope study of coronary bypass grafts

Scanning electron microscope studies of coronary bypass grafts were carried out in six routine bypass operations. Infusion of the initial crystalloid cardioplegic medium into the aortic root after aortic cross clamping was performed in every case. In two cases, pieces of aorta below and above the cross-clamped site, le, having and not having had contact with the crystalloid cardioplegic medium, were studied. The endothelial lining of the veins showed normal structure following distention with blood. Following infusion with a crystalloid cardioplegic solution, the endothelial cells had almost completely vanished and the flow surface was composed mainly of collagen fibers. The aortic samples taken from below the cross-clamp site showed similar destruction of the endothelium that was observed in vein grafts after crystalloid cardioplegic solution infusion, whereas the aortic samples taken from above the cross-clamp site disclosed normal endothelium.     

Ischemic myocardial protection. Comparison of nonoxygenated crystalloid, oxygenated crystalloid, and oxygenated fluorocarbon cardioplegic solutions

This study was designed to compare myocardial protection with a nonoxygenated crystalloid solution, an oxygenated crystalloid solution, and an oxygenated fluorocarbon cardioplegic solution. Postischemic ventricular performance was studied in three equal (N = 7) groups of dogs subjected to 120 minutes of global ischemia induced at an average myocardial temperature of 18.5 degrees +/- 1.4 degrees C (range 17.0 degrees to 21.0 degrees C). Left ventricular global and regional function was evaluated by sonomicrometry and micromanometers before ischemia and at 45 and 60 minutes after ischemia. Stroke volume index, left ventricular pressure-minor external diameter loop area, percent shortening, first derivative of left ventricular pressure, mean velocity of circumferential fiber shortening, and the slope of the end-systolic pressure were used to evaluate myocardial contractility. In vitro oxygen content of the three cardioplegic solutions was measured at a mean injection temperature of 8.3 degrees +/- 0.6 degrees C: 0.8 +/- 0.1 vol% (nonoxygenated crystalloid cardioplegia), 3.2 +/- 0.2 vol% (oxygenated crystalloid cardioplegia), and 6.2 +/- 0.2 vol% (oxygenated fluorocarbon cardioplegia). Recovery of global and regional function was significantly (p less than 0.05) better with both oxygenated solutions than with the nonoxygenated solution. Differences between the oxygenated crystalloid and fluorocarbon groups were not significant. We conclude: (1) Compared to nonoxygenated crystalloid cardioplegia, oxygenated crystalloid and oxygenated fluorocarbon cardioplegic solutions gave superior myocardial protection during 2 hours of ischemic arrest; (2) no difference was found in protective effects between an oxygenated crystalloid and an oxygenated fluorocarbon solution.     

Effects of cardioplegic solutions on coronary artery and myocardium--comparison of the glucose-insulin-potassium solution and the St. Thomas' Hospital cardioplegic solution

Effects of two cardioplegic solutions on coronary artery and myocardium were experimentally investigated in three types of preparations. In the isolated perfused guinea pig heart, infusion of Glucose-Insulin-Potassium (GIK) solution (37 degrees C) caused contraction of coronary artery, whereas the St. Thomas' Hospital cardioplegic solution (37 degrees C) produced vasodilation. At the end of 30 minutes reperfusion after continuous infusion of cardioplegic solution, the St. Thomas' Hospital cardioplegic solution produced a greater recovery of cardiac function than GIK solution. In the isolated pig coronary artery, vasoconstriction caused by high potassium content was diminished by addition of magnesium in concentration dependent manner. In the electrophysiological examination, the membrane potential of the guinea pig papillary muscle was recorded by means of conventional glass microelectrodes. Though GIK solution produced greater depolarization of resting membrane potential than the St. Thomas' Hospital cardioplegic solution, effects of the two different cardioplegic solution was not so different after reperfusion of Tyrode solution. The St. Thomas' Hospital cardioplegic solution resulted in greater recovery of contracting activity after reperfusion than GIK solution. These data suggest that GIK solution causes coronary vasoconstriction and has deleterious effects on myocardium and that the St. Thomas' Hospital cardioplegic solution has a vasodilating action and produced a greater myocardial protection than GIK solution.     

Experimental evaluation of myocardial protective effect of prostacyclin analog (OP-41483) as an adjunct to cardioplegic solution

A stable prostacyclin analog (OP-41483) was evaluated for myocardial protective effect against global ischemia with the use of cardioplegia. Isolated canine hearts (n = 25) were exposed to 60 minutes of warm (37 degrees C) global ischemia after the arrest by crystalloid cardioplegia. Prostaglandin analog was given in three different ways: preadministration (700 ng/kg body weight per minute) before ischemia for 30 minutes (group I, n = 5), given as a component of cardioplegic solution (600 ng/ml, group II, n, = 6), and post-administration (25 ng/kg body weight per minute) during reperfusion for 30 minutes (group III, n = 7). During reperfusion, coronary sinus blood flow, 6-keto-prostaglandin F1 alpha in coronary sinus blood, and myocardial oxygen consumption were measured during reperfusion. As a result, groups II and III showed significantly better global left ventricular function (developed pressure, maximum dP/dt, and diastolic compliance) than the control group (without prostaglandin analog, n = 7) and group I. Myocardial oxygen consumption at reperfusion (1 minute) was significantly larger in group II than in the control group. 6-keto-prostaglandin F1 alpha flux was significantly larger in group II than in the other three groups during reperfusion. The results indicated that prostaglandin analog has a beneficial effect on myocardial protection under global ischemia with cardioplegia, particularly when used as a component of cardioplegic solution and also during reperfusion. The mechanism may relate to the cytoprotective effect (including protection of endothelium with enhanced endogenous prostacyclin production at reperfusion and also to the modulation of reperfusion per se.     

Effect of an oxygen-enriched solution and multiple dosing of antegrade crystalloid cardioplegic solution on myocardial metabolism during coronary artery bypass graft operations.

The metabolic effect of excessive oxygenation and frequency of administration of antegrade crystalloid cardioplegic solution was assessed in 33 patients undergoing routine coronary artery bypass graft operations. Four patient groups were designed in which the initial aortic root injection was 1000 ml and then 100 ml administered through the vein grafts after completion of each distal anastomosis. The groups were divided as follows: group 1, single dose, normally oxygenated cardioplegic solution infused via the aortic root; group 2, single dose, high oxygen content cardioplegic solution infused via the aortic root; group 3, normally oxygenated cardioplegic solution with additional 250 ml doses via the aortic root every 20 minutes; group 4, high oxygen content cardioplegic solution with additional 250 ml doses via the aortic root every 20 minutes. In all groups myocardial mean septal temperature showed an immediate fall to approximately 11 degrees C with the initial aortic root doses and then a gradual rewarming to approximately 20 degrees C during the crossclamp period (mean 58.6 minutes). Metabolic parameters measured or calculated from the coronary sinus effluent were myocardial oxygen extraction, lactate production, base deficit, inorganic phosphate, glucose, potassium, creatine kinase (total and myocardial band fraction), and catecholamine production. There was no statistically significant difference in any of these determinations between each patient group. Furthermore, myocardial recovery, myocardial performance, and postoperative recovery characteristics were not different. We conclude that single or multidose aortic root crystalloid cardioplegic solution (either oxygen enriched or normally oxygenated) is equally effective in routine coronary artery bypass graft operations when septal temperatures are maintained between 15 degrees and 21 degrees C for a total arrest time of 60 minutes or less. In this study, increasing the volume cardioplegic solution given in multiple doses appeared to offer no significant metabolic or functional advantage in patients without complications who had satisfactory left ventricular function.     

Effect of pH shifts induced by oxygenating crystalloid cardioplegic solutions

Oxygenation of a bicarbonate-containing crystalloid cardioplegic solution alters the partial pressure of both oxygen (O2) and carbon dioxide (CO2). Therefore, oxygenating St. Thomas' Hospital II plus glucose (11 mmol/L) cardioplegic solution with 95% O2 + 5% CO2 induces a pH shift to 7.0 (10 degrees C) as opposed to pH 9.3 with 100% O2. In an isolated working rat heart model, we show that pH 7.0 (10 degrees C) improves mechanical postischemic recovery in the absence or presence of O2. However, in the absence of O2, pH 7.0 appears to inhibit glycolysis and diminish the stability of cellular membranes. The provision of O2 independently improved mechanical recovery and at pH 7.0, improved the preservation of the sarcolemma. Increasing the O2 content by including a perfluorocarbon (FC-43) in the oxygenated St. Thomas' plus glucose cardioplegia is not additionally beneficial. St. Thomas' Hospital plus glucose cardioplegic solution should be oxygenated, but with 95% O2 + 5% CO2 and not 100% O2.     

Transesophageal echocardiographic evaluation of aortic valve integrity with antegrade crystalloid cardioplegic solution used as an imaging agent.

Forceful intravascular injection of crystalloid causes microbubble (cavitation) formation. The resulting ultrasound-opaque medium is widely used in echocardiography as a source of contrast. The following study was performed to determine the feasibility of using antegrade crystalloid cardioplegic solution as a transesophageal two-dimensional echocardiographic imaging agent to evaluate aortic valve integrity. In patients with preexisting aortic regurgitation (n = 12), cardioplegic solution administration (driving pressure 150 to 200 mm Hg) was associated with the appearance of intracardiac cavitations in 12 of 12 patients. Among patients without preexisting valve dysfunction (n = 22), intracardiac cavitations were manifested in 20 of 22, with extension of the cavitations to the left atrium in 17. Associated cardiac dimensions (left ventricular outflow tract area and left ventricular diameter) did not exceed preceding cardiopulmonary bypass values in these patients (2.0 +/- 1.6 cm2 versus 2.6 +/- 1.2 cm2 and 1.4 +/- 0.7 cm versus 1.5 +/- 0.8 cm, respectively). It was concluded that antegrade crystalloid cardioplegic solution can be used as an echocardiographic contrast agent in this context. The inability to establish a relationship between the extent of cardioplegic intracardiac penetration and left ventricular dimensional changes limits the technique, as presently employed, to qualitative analysis of valve dysfunction.     

Clinical study of the effect to myocardial protection with crystalloid cardioplegic solution during open heart surgery in infants under age 3 months

We investigated the effect to myocardial protection with crystalloid cardioplegic solution (Kurume solution I (S-I)) during open heart surgery in 21 infants less than 3 months old. The mortality was 28.6% (6 cases) including 2 patients having peroperative severe acidosis or shock. It was suggested that about half of them died of inadequate myocardial preservation. Comparing factors in the deaths with the survivors, there were significant differences between them in extracorporeal circulation time (ECCT) (196.7 +/- 50.1 min versus 133.2 +/- 45.8 min, p less than 0.01) and aortic-cross clamping time (ACCT) (120.0 +/- 45.8 min versus 78.3 +/- 30.5 min, p less than 0.05). In survivors, 86.7% of them required the effective dose (more than 6 micrograms/kg/min) of catecholamine and 33.3% presented low cardiac output syndrome (with the dose of more than 10 micrograms/kg/min and more than for 48 hours). The incidence of LOS was related to ECCT and ACCT. Thus it seemed that infant was more susceptible than older patient to the effects of ECC and the operation was carried out safely with ECCT less than 150 minutes and ACCT under age 3 months, it is necessary to use the cardioplegic solution fitting immature myocardium and to design operative technique and assist device for open heart surgery to shorten ECCT and ACCT.     

Effects of cardioplegic solution on human contractile element velocity.

A technique for measuring the maximum contractile element velocity (Vpm) of the myocardium was developed, verified, and employed in patients to allow accurate intraoperative assessment of the adequacy of myocardial protection. Four groups of patients were studied. Ten patients had coronary artery bypass grafts (CABG) with cardioplegia; 13 had CABG with coronary perfusion, ventricular fibrillation at 28 degrees C, and aortic clamping for distal anastamoses; 6 had aortic valve replacement (AVR) with cardioplegia; and 7 had AVR with coronary perfusion to the beating heart. For cardioplegia, a solution of 5% dextrose in 0.2% saline at 4 degrees C with 25 mEq of potassium chloride and 12.5 gm of mannitol was infused initially, followed by 500 ml every 30 minutes. Clinically all patients did well, and there were no deaths. Patients having CABG with intermittent coronary perfusion during ventricular fibrillation had significant (p less than 0.01) depression of Vpm from 38.3 to 30.8 sec-1 while Vpm in patients having CABG with cardioplegia was unchanged. Patients having AVR with continuous coronary perfusion or with cardioplegia (average anoxia time, 70.4 minutes) had no significant change in Vpm. We conclude that this cardioplegic solution provided adequate protection of myocardial function for up to 105 minutes of continuous aortic clamping in humans. The depression in Vpm observed following CABG with intermittent coronary perfusion is consistent with previous suggestions that this combination is detrimental because of maldistribution of coronary blood flow during ventricular fibrillation.     

Effects of synthetic blood and crystalloid cardioplegic solutions on coronary endothelium: An experimental scanning electron microscope study

In an experimental study the effects of Fluosol DA (added with potassium chloride) on the vascular interface and endothelial cells were compared to those of crystalloid potassium cardioplegic solution using scanning electron microscope. Twenty rabbits (10 in each group) were sacrificed, the hearts with ascending aorta were immediately excised, and cold oxygenated solution was infused via a cannula inserted into the cross-clamped aorta. The hearts were left immersed in the perfusion medium for 2 hr. In the Fluosol DA group endothelial cover and endothelial cells were normal or minimal changes were seen in seven cases. Occasional breaking of intercellular attachments, small areas of denuded flow surface, and disappearance of microvilli were seen in three cases. In the crystalloid potassium cardioplegic group 7 of the 10 cases showed moderate or severe damage with large areas of denuded flow surface. The present experimental protocol represented an extreme situation where no collateral coronary blood was present. The coronary endothelial damage was obvious after the crystalloid potassium cardioplegic solution. Similar damage was not found following Fluosol DA infusion.