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Reperfusion effects on the magnesium-procaine arrested rabbit heart.

Rabbit hearts were subjected to cardiac arrest induced by injecting 3 isotonic cardioplegic solutions each of which contained in combination with procaine-HCl one of 3 different magnesium compounds. A period of 40 min arrest was followed by reperfusion of 15 min. A regular sinus rhythm returned after washout of the cardioplegic solution. The pattern of the essentially unaltered myocardial ultrastructure correlated with the well-preserved high-energy phosphate stores. The effects of magnesium and procaine on cell permeability and the consequences of the different fusion are discussed. The study stresses the importance of an adequate period of postischemic reperfusion of the heart in an unloaded state in support of myocardial recovery. The studies presented herein suggest further investigations of various concentrations of magnesium and procaine combined with different amounts of calcium in perfusates for the preservation of the heart and possibly of other organs.

Animals↗

Effect of intraventricular pressure on protein synthesis in arrested rat hearts.

A modification of the Langendorff technique for perfusion of rat hearts was developed to allow a constant intraventricular pressure to be imposed on the left ventricle of arrested-catheterized hearts. This model was used to assess effects of increased aortic (60 and 120 mmHg) and intraventricular (0 and 25 mmHg) pressures on the rate of protein synthesis between 70 and 130 min of perfusion and on contents of ATP and creatine phosphate (creatine-P) in ventricles. Rates of protein synthesis in atria also were measured. Increased intraventricular or aortic pressure elevated the rate of protein synthesis (41%) compared with hearts supplied an aortic pressure of 60 mmHg and an intraventricular pressure of 0 mmHg. Higher intraventricular pressure also decreased the ribosomal subunit content. No change in the rate of protein synthesis was observed when intraventricular pressure was raised in hearts supplied an aortic pressure of 120 mmHg. Rates of atrial protein synthesis and contents of ATP and creatine-P were unchanged by elevations of either intraventricular or aortic pressure. These experiments indicate that stretch of the ventricular wall due to higher intraventricular or aortic pressure accelerated protein synthesis by maintaining the in vivo balance between rates of peptide chain initiation and elongation.

Adenosine Triphosphate↗

A comparative study of cardiac preservation with Celsior or University of Wisconsin solution with or without prior administration of cardioplegia.

BACKGROUND: We have previously reported the cardiac functional and metabolic benefits of administration of extracellular-type cardioplegia before preservation with University of Wisconsin solution. Celsior solution was designed to be used both as an arresting solution and a storage solution for heart transplantation. The objective of the present study is to compare cardiac function of hearts arrested and preserved with Celsior solution to hearts arrested with cardioplegia followed by preservation with UW solution. METHODS: Rabbit hearts were divided into 4 groups: in the Celsior group, hearts were arrested and preserved with Celsior solution; in the C-Celsior group, hearts were arrested by an extracellular-type cardioplegia and preserved with Celsior solution; in the UW group, hearts were arrested and stored in University of Wisconsin solution; and, in the C-UW group, hearts were arrested with extracellular-type cardioplegia and stored in University of Wisconsin solution. After 6 hours of preservation, cardiac function was measured using modified Frank-Starling curves in the isolated blood-perfused working heart. RESULTS: Cardiac function in the Celsior group was inferior to that in both the C-UW group and UW group. The C-Celsior group demonstrated inferior cardiac function compared with the Celsior group (p < 0.01), whereas no significant difference was observed between the C-UW and UW groups. CONCLUSIONS: Celsior solution did not surpass UW solution regardless of the use of cardioplegia. Further studies are required to develop optimal solution for use as both an arresting solution and a storage solution.

Adenosine↗

Cardiac arrest and heart attack: an evaluation of lay knowledge.

Random samples of Dunedin residents were interviewed before and after the publication in the telephone directory of an information sheet on cardiac arrest and heart attack. Most subjects had heard of both cardiac arrest and heart attack but almost half of the samples were either wrong in identifying which was the more serious or they did not know. One-third of the post-publication sample had looked at the information sheet. Results indicate limited awareness of all but the most elementary medical facts and the existence of a variety of confusions and misconceptions in the two samples. Problems of comprehension and remembering are discussed in the context of the communication of medical information by doctors and health educators.

Adult↗

Retrograde continuous warm blood cardioplegia: a new concept in myocardial protection.

This report presents the results in our first clinical series of patients receiving continuous warm blood cardioplegia through the coronary sinus. Warm oxygenated blood cardioplegia has certain theoretical advantages, such as continuously supplying oxygen and substrates to the arrested heart while avoiding the side effects of hypothermia. Retrograde infusion of cardioplegia also offers certain advantages (eg, in valve operations and in patients with severe coronary artery disease) that are complementary to warm blood cardioplegia. Retrograde warm blood cardioplegia was used in 113 consecutive patients (85 men and 28 women with a mean age of 61 years) undergoing various procedures. Three percent of the patients died, 7% needed transient intraaortic balloon pump support, 6% had evidence of perioperative myocardial infarction, and 96% had spontaneous return of rhythm. There were no coronary sinus injuries. This new technique of retrograde continuous warm blood cardioplegia is a simple, safe, and reliable method of myocardial protection that may change the way we currently protect the heart intraoperatively.

Adult↗

Port-Access cardiac surgery using endovascular cardiopulmonary bypass: theory, practice, and results.

BACKGROUND: Reduction of surgical trauma is the aim of minimally invasive cardiac surgery. This can be achieved by reducing the size of the incision or by eliminating or changing the cardiopulmonary bypass system. However, certain cardiac surgical procedures, such as valvular surgery and complex multivessel coronary artery surgery, are not feasible without the use of cardiopulmonary bypass. Therefore endovascular cardiopulmonary bypass may allow reduction of surgical trauma for these patients. METHODS: Since its first application in April 1995, more than 1100 procedures have been performed worldwide using the EndoCPB endovascular cardiopulmonary bypass system. The authors' experience consists of 60 Port-Access coronary artery bypass grafting procedures, 34 Port-Access mitral valve procedures (18 replacements, 16 repairs), 5 atrial septal defect closures, and 3 atrial myxoma removals. RESULTS: The patient survival rate was 99%, the incidence of perioperative stroke was 1%, and the incidence of aortic dissection was 1%. In the Port-Access mitral valve and atrial septal defect patients, the survival rate was 100% with no peri- or postoperative complications. Peri- and postoperative transesophageal echocardiography revealed no perivalvular leak or remaining mitral insufficiency after valve repair. CONCLUSIONS: The EndoCPB endovascular cardiopulmonary bypass system allows the application of true Port-Access minimally invasive cardiac surgery in procedures that require the use of cardiopulmonary bypass and cardioplegic arrest. Sternotomy and its potential complications can be avoided, and the surgical procedures can be performed safely on an empty, arrested heart with adequate myocardial protection.

Adult↗

Endoventricular patch reconstruction in large ischemic wall-motion abnormalities.

Endoventricular patch plasty (EVPP) has been used since 1984 to rebuild the left ventricle. The global experience of our group includes more than 835 cases. Large wall-motion abnormalities were detected by the center line method when > 60% of the circumference of the left ventricle was asynergic. In this series, 269 patients had an ejection fraction < 30%. Surgery for repair of large wall-motion abnormalities was conducted on the arrested heart with insertion within the left ventricle of a patch rebuilding the contractile area while leaving a residual volume between 50 and 70 cc/m2 of body surface. The global results of the technique of EVPP are analyzed on the last 700 operated patients. Three series of patients with large wall-motion abnormalities were examined. We conclude that this technique is appropriate in advanced stages of ischemic disease as an alternative to cardiac transplant. At an operative risk of approximately 12%, improvement is obtained in 80% of cases.

Blood Vessel Prosthesis Implantation↗

Long-term effects of cold cardioplegic myocardial protection in the rat.

The long-term histologic effects of the use of two cold cardioplegic solutions (St. Thomas' and saline) were studied and compared in a model of heterotopic cardiac transplantation in rats of isogeneic strain. After cold cardioplegic arrest, hearts were stored for varying times ("minimal," 30, or 90 minutes) in one of the solution prior to transplantation, giving a total of six groups (five animals in each group). Early assessment of myocardial injury 48 hours after transplantation was by the uptake of technetium 99m pyrophosphate and by measurement of serum creatine kinase activity. Late assessment of myocardial injury at 3 months after transplantation was by quantitative histologic examination. The findings indicated that significant myocardial fibrosis occurred in hearts stored in both solutions for the longest storage period (90 minutes) and that St. Thomas' cardioplegic formula conferred better myocardial protection after 90 minutes' storage than did cold saline, as judged by the degree of histologic injury at 3 months (p less than 0.025). Significant correlation was found between long-term histologic changes at 3 months and the uptake of technetium 99m pyrophosphate (p less than 0.001) and serum creatine kinase activity (p less than 0.05) assessed at 48 hours. Uptake of technetium 99m pyrophosphate and increased serum creatine kinase activity was demonstrated 48 hours after injury in animals having no detectable histologic injury at 3 months. These observations indicate that there may be technetium 99m pyrophosphate uptake and enzyme release from reversibly damaged myocardial cells.

Animals↗

Improved protection of chronically inflow-limited myocardium with retrograde coronary sinus cardioplegia.

The effects of retrograde coronary sinus cardioplegia (CSC) and conventional aortic route cardioplegia (ARC) on reperfusion blood flow patterns were compared in 18 mongrel dogs having ameroid-induced coronary collaterals. Animals were placed on cardiopulmonary bypass and cooled systemically. The aorta was clamped, and the hearts were arrested with a bolus infusion of hypothermic (4 degrees C) hyperkalemic cardioplegic solution delivered either into the aortic root or through a balloon catheter placed in the coronary sinus. After 45 minutes of ischemic arrest, hearts were reperfused, and blood flow patterns were measured at 1, 5, 10, and 60 minutes. In the normal region, a significant hyperemia occurred with both CSC and ARC. However, the peak reactive transmural flow was 120% more with ARC than with CSC (4.55 +/- 0.45 vs. 2.12 +/- 0.19 ml/min/g, respectively; p less than 0.05) and remained elevated after 60 minutes of reperfusion, when CSC flows had returned to control levels. In the collateral-dependent region, a significant hyperemia was observed with ARC that persisted throughout reperfusion. However, with CSC, no significant changes in blood flow were detected at any time during reperfusion. Thus, the decreased hyperemic response after arrest suggests a reduced energetic debt with CSC compared with ARC and may indicate superior myocardial protection with CSC. This is particularly evident in chronically inflow-restricted myocardial regions.

Animals↗

Effects of recombinant human extracellular-superoxide dismutase type C on myocardial reperfusion injury in isolated cold-arrested rat hearts.

The efficacy of recombinant human extracellular-superoxide dismutase type C (EC-SOD C) on myocardial reperfusion injury was explored in hypothermically arrested rat hearts, as was its site of action. Forty isolated working rat hearts were subjected to 30 min of global ischemia followed by 30 min of reperfusion. The hearts were arrested by the administration of 10 mL of cold perfusate at the onset of ischemia. At the same time, they were randomly assigned to one of five groups; A: cold perfusate only; B: cold perfusate + EC-SOD C 10.4 mg/L (30,000 U/L); C: cold perfusate+bovine CuZn-SOD 7.5 mg/L (30,000 U/L); D: cold perfusate + EC-SOD C 10.4 mg/L + heparin 50,000U/L; E: cold perfusate + heparin 50,000 U/L. Heparin was given to prevent binding of EC-SOD C to endothelial cell surfaces. Left ventricular function was studied before ischemia and at the end of reperfusion. Percent recovery of maximal left ventricular dP/dt after reperfusion was more pronounced in group B (109 +/- 24%; p less than .05) than in groups A (42 +/- 40%), C (47 +/- 36%), D (44 +/- 33%) and E (58 +/- 25%). Likewise, percent recovery of the double product (heart rate x systolic left ventricular pressure) was better in group B (104 +/- 18%; p less than .05) than in the other groups (A: 47 +/- 37%, C: 49 +/- 36%, D: 50 +/- 35%, E: 69 +/- 31%). Compared to the preischemic level, creatine kinase increased significantly in the coronary effluent after reperfusion in groups A, C, D, and E, but not in group B. The results suggest that EC-SOD C, which attaches to the endothelial cell surfaces, might be particularly effective as protection against myocardial reperfusion injury when given together with cardioplegic solution.

Animals↗

Right and left ventricular volumes and wall measurements: determination by computed tomography in arrested canine hearts.

Computed tomographic (CT) images of in vitro hearts filled with iodinated contrast medium have delineated right and left ventricular cavities, papillary muscles, major trabeculae, pulmonary artery, and the aorta. Because of relatively good structural definition, this study was undertaken to determine the potential use of CT in the measurement of cardiac dimensions and cavity volumes. Ten isolated arrested canine hearts were filled with an iodinated oil-paraffin mixture and scanned transversely from base to apex. Measurements of the thickness of the interventricular septum and of the left ventricular posterior wall (indexes of cardiac hypertrophy) had a high degree of correlation to similar measurements of corresponding heart specimens. Using serial tomographic images, the cavity volumes of individual tomographic scans were totaled. The volume of each scan of given thickness was obtained either by the use of planimetry or from a numerical computer printout. Both the planimetric and computer methods gave right and left ventricular volumes which correlated well (P less than .05) with the volumes of paraffin casts. Unlike other techniques widely used for ventricular volume measurement, the method described does not depend on an assumption that the chamber resembles a specific geometric model. This method of volume measurement is applicable to both the left ventricle, regardless of its shape, and to the concave irregularly shaped right ventricle.

Animals↗

Left ventricular mechanics in arrested dog heart: effects of ventricular interaction and vascular volumes.

The present study was designed to determine the effects of right heart pressure on the compliance of the left ventricle (LV). The studies were conducted on isolated, blood-perfused, potassium-arrested dog hearts with vasomotor tone either present (n = 5) or absent (n = 8). A balloon was used to control LV volume, whereas right heart (RHP) or coronary sinus (CSP) pressures were controlled via a column placed in the right heart or coronary sinus, respectively. Control of CSP independently of RHP allowed us to assess the relative contribution of coronary venous pressure to changes in LV compliance under conditions of elevated RHP. LV volume and compliance at a LV pressure of 15 mmHg (V15 and C15, respectively) were calculated to quantify the shift and slope changes of the LV pressure-volume (P-V) relationships. V15 and C15 decreased with vasomotor tone present from 52.8 +/- 1.4 ml and 1.7 +/- 0.1 ml/mmHg at control, to 43.3 +/- 2.1 ml and 1.4 +/- 0.1 ml/mmHg (P < 0.05) with RHP = 0 and 20 mmHg, respectively. Similar effects were obtained with vasodilation, but C15 was significantly lower relative to autoregulation but C15 was significantly lower relative to autoregulation (1.0 +/- 0.1 at control RHP, P < 0.05). Elevation of CSP with vasomotor tone resulted in an upward shift in the LV P-V relationship: V15 decreased from 53.4 +/- 2.1 at CSP = 0 mmHg to 50.9 +/- 1.6 ml at CSP = 20 mmHg (P < 0.05). After vasodilation there was no detectable shift in the LV P-V relationship with elevation of CSP.

Animals↗

Transplantation of the canine cadaver heart using a core-cooling technique.

We studied whether a cardiopulmonary bypass (CPB) and a core-cooling technique could resuscitate an arrested heart, and whether this procedure benefited canine cadaveric heart transplantation. Donor dogs were subjected to brain death by an intracranial balloon technique, and then, to cardiac arrest conducted by cutting off ventilatory support. In the control group (Group 1; n = 8), arrested hearts were flushed with cardioplegic solution and harvested thereafter without any resuscitation technique. In the experimental group (Group 2; n = 8), arrested hearts were once resuscitated using CPB, and then harvested using a core-cooling technique and cardioplegia. These hearts were transplanted orthotopically. Seven of eight recipients in Group 1 were weaned from CPB, and five of them finally became independent of dopamine administration. All recipients in Group 2 were successfully weaned from CPB, and also became dopamine free eventually. In Group 2, all post-transplantation hemodynamic values such as cardiac output during the period of dopamine administration were equivalent to those of post-brain death period. Chemical analysis of the serum and myocardial muscle demonstrated no difference between groups. We conclude that CPB combined with a core-cooling technique makes it possible to utilize an arrested heart as a donor organ for transplantation.

Animals↗

Myocardial protection from ischemic arrest: potassium and verapamil cardioplegia.

Prolonged normothermic myocardial ischemic arrest results in myocardial dysfunction. This study has investigated the technique of preserving myocardial function by a single bolus intracoronary infusion of combination potassium and verapamil at the onset of ischemic arrest. Sixty-one dogs underwent cardiopulmonary bypass with 60 min of ischemic arrest: 25 received no myocardial protection, 12 received a single intracoronary bolus of KCl, 12 received combination verapamil and KCl, and 12 received verapamil alone. Following the ischemic arrest, hearts protected by combination of potassium and verapamil demonstrated better survival evidenced by the ability of all 12 dogs to resume normal hemodynamic function. The hemodynamic function in the combination potassium and verapamil group also demonstrated better cardiac output, left ventricular dF/dt, and myocardial segment shortening than survivors in the other groups. Subsarcolemmal (SSL) and intermyofibrillar IMF) mitochondria were isolated from these hearts and function evaluated. NADH-linked oxygen consumption was impaired as was calcium transport in the SSL from unprotected ischemic hearts. Intermyofibrillar mitochondria were not different from control or sham. The hearts protected by verapamil and potassium demonstrated normal mitochondrial function.

Animals↗