Inhibition of protein kinase C (PKC) response of voltage-gated calcium (Cav)2.2 channels expressed in Xenopus oocytes by Cavß subunits.

Cav2.2 channels are a substrate for phosphorylation by protein kinase C (PKC) isozymes. The contribution of Cavß, an auxiliary subunit of these channels, in the PKC modulation was studied. Cav2.2 channels were expressed in Xenopus oocytes in various subunit combinations with or without Cavß subunits. Currents were recorded using a two-electrode voltage clamp with barium as the charge carrier (IBa). Acetyl-ß-methylcholine (MCh), an activator of PKCα, potentiated Cav2.2 currents expressed with Cav2.2α1 alone or Cav2.2α1α2/δ. Similarly PKC isozymes α, ßII or ɛ potentiated IBa through Cav2.2α1 subunit channels. In contrast, MCh failed to potentiate currents expressed with Cav2.2α1 and Cavß1b, ß2a, ß3 or ß4 subunits. Similarly, in the presence of Cavß1b subunits, PKC isozymes failed to potentiate these currents; contrarily, PKCs α or ßII decreased the IBa. MCh failed to potentiate Cav2.2α1 subunit currents in the serine/threonine (Ser/Thr)→alanine mutants, T422A, S1757A or S2132A of Cav2.2α1 subunits. Hence Thr-422, Ser-1757 and Ser-2132 may be PKCα isozyme target sites. The action of PKC on these sites was further substantiated by the increased basal IBa along with the loss of MCh potentiation when Ser/Thr was mutated to aspartate. The observation that MCh or PKC isozymes failed to affect Cav2.2 currents in the presence of Cavß subunits suggests that these subunits may have interfered with the interaction between PKC and Ser/Thr sites of Cav2.2α1 subunits. In addition to affecting channel expression and current kinetics, Cavß subunits may also modulate the response of these channels to neurochemicals.

Coexistent coronary and cerebrovascular disease: results of simultaneous surgical management in specific patient groups.

OBJECTIVE: Results of synchronous combined revascularization were examined in specific patient groups with coexistent coronary and cerebrovascular diseases. METHODS: Between 1.1.1980 and 31.12.1998, 408 patients underwent a synchronous combined carotid endarterectomy (CEA)+myocardial revascularization (CABG). In 259 (63.5%) patients, carotid disease was asymptomatic. Remaining patients presented with a previous stroke (n=35) or a transient ischemic episode (TIA) (n=114). In 245 (60%) patients, carotid stenosis was bilateral (Group A: bilateral > or =80% stenosis, Group B: contralateral occlusion, Group C: contralateral subcritical disease). A synchronous ipsilateral CEA+CABG was performed in all patients with an unilateral disease (n=163) and also in all Group B (n=33) and Group C (n=142) patients with bilateral disease. A simultaneous bilateral CEA+CABG was performed in 12 high risk Group A patients. Remaining Group A patients (n=58), initially underwent an ipsilateral CEA for most dominant lesion+CABG, soon followed by the contralateral CEA. Results were examined in above specific patient Groups. RESULTS: Overall combined hospital mortality from stroke+myocardial infarction was 2.45%. No independent predictor of stroke was identified. In general, initial prophylactic CEA, subdued the risk of subsequent strokes for 7-8yr. Predictors of a late stroke were: progression of bilateral (P=0.007) and intracranial (P=0.04) cerebrovascular disease. Highest risk of an early stroke was recorded in Group A patients. A composite high risk group of patients with multiple risk factors (n=155) demonstrated a higher risk of both early and late strokes, as compared to the remaining patients (n=253) (P<0.04). Observed risk of early and late strokes, in specific patient groups was lower than standard predictions. CONCLUSIONS: A regular use of combined approach was justified in the above patient groups.

Iaterogenic injuries during retrograde delivery of cardioplegia.

During last eight years, retrograde delivery of cardioplegia was used on a regular basis, utilizing a DLP INC (Grand Rapids, MI) or a Research Medical INC (Salt Lake City UT) delivery systems, in almost an equal number of patients. This method resulted in a high pressure rupture, or perforation of the coronary sinus, its radicals or the right ventricle (RV) in 0.06% (5/7886) of patients. Intraoperative diagnosis of these injuries were confirmed on abnormal haemodynamic tracings and trans oesophageal echocardiography (TOE), and appearance of cardiac contusion or leakage of cardioplegia. A low incidence of these iaterogenic injuries may be attributed to: (1) a regular use of this method and (2) use of TOE guided manipulations in select high risk and reoperative patients. Repair of these injuries, as described, resulted in salvage of 4/5 (80%) patients.

Postoperative acute refractory right ventricular failure: incidence, pathogenesis, management and prognosis.

Isolated acute refractory right ventricular failure is extremely uncommon. There are greater prospects of seeing a right dominant biventricular failure, as the two ventricular chambers are contiguous. The overall clinical spectrum is determined by the relative ischemic involvement of the right or left ventricle. The postoperative acute refractory right ventricular failure that develops after cardiotomy, heart transplant, or during a left ventricular assist device support, may have somewhat dissimilar elements of origin, but the resultant clinical picture and the management are essentially similar. In this collective review, the authors have summarized the incidence, pathogenesis, management and prognosis of postoperative acute refractory right ventricular failure, in adult cardiac surgical practice. The incidence of post-cardiotomy acute refractory right ventricular failure ranges from 0.04 to 0.1%. Acute refractory right ventricular failure has also been reported in 2-3% patients after a heart transplant and in almost 20-30% patients who receive a left ventricular assist device support. The main contributor to this problem is a disproportionate ischemic involvement of the right ventricle. Other pertinent contributors to this problem are pulmonary hypertension and an altered interventricular balance. The latter component is predominant in recipients of a left ventricular assist device support. Postoperative acute refractory right ventricular failure has been successfully managed with conventional pulmonary vasodilators, mechanical support with a pulmonary artery balloon pump, a right ventricular assist device, or cavopulmonary diversion. Unfortunately, the reported initial salvage rate is only 25-30%. This problem is often underestimated. Support measures are often started late or terminated prematurely. These factors have contributed to a poor initial salvage rate in this group of patients.

Leukocyte activation during cardiopulmonary bypass: limitations of the inhibitory mechanisms and strategies.

Cardiopulmonary bypass, initiates a generalised response, which is primarily defensive in nature. This response is self regulated and terminated spontaneously. Obvious problems are complement and leucocyte activation, but several other cascades are also stimulated, which interact, accentuate or modulate this response. These supporting cascades include, release of inflammatory cytokines, an activation of kallikrein system, clotting and fibrinolytic mechanisms, and arachidonic acid metabolism. Because of an effective autoregulatory mechanism, only a small proportion of patients (<3%), undergoing cardiopulmonary bypass are adversely effected by this process. Prognosis of these patients is often unpredictable, but in general, high risk patients are likely to suffer most. A number of specific and non specific artificial measures have been introduced to control postperfusion problems, resulting from this process. These control measures are usually effective against a specific component of this generalised problem, and often fail to achieve desired effects. Efficacy of control measures is further limited by a continued activation of complement and leucocytes, via interactions between the mentioned inflammatory cascades. In view of these limitations, we have introduced certain modifications in our previously reported control strategy. These include an early identification of high risk and susceptible individuals and using specific inhibitors of complement activation for both initial and terminal stages.

Reinterventions for recurrent ischemic heart disease following a successful first re-do myocardial revascularization: predictors, indications and results.

Predictors for a reintervention following a successful first re-do surgical revascularization (CABG) were examined. Success and limitations of the reintervention procedures were evaluated. Between 3/88 and 3/95, 16.81% (302/1796) patients who had undergone a first re-do CABG surgery in the authors' center, required a reintervention. Graft angioplasty was performed in 158 (52.32%) patients and a second re-do CABG in 47.68% (n = 144). Graft angioplasty was preferred over surgery in patients aged 70 years or older (43% versus 24.3%, P<0.001) and in patients with unstable angina (55.6% versus 33.3%, NS) or a Left Ventricular Ejection Fraction (LVEF) <30% (34.8% versus 20%, P<0.05). Re-do CABG was preferred over graft angioplasty for multivessel revascularization (3+/-0.3 versus 1+/-0.6, P<0.001), proximal occlusive disease (P<0.001) and for graft disease of a longer duration (7.18+/-1.7 years versus 3+/-0.6 years, P<0.01). The independent predictors of a reintervention were (i) lack of arterial revascularization and (ii) inability to achieve a complete revascularization in a previous operation. The predictors of a failed graft angioplasty were diameter stenosis >70%, long occlusive lesions (multivariate), angulation, calcification and asymmetrical lesions (univariate). Failed graft angioplasty required a re-do CABG (n = 48: early 21, late 27), repeat graft angioplasty (n = 34: early 8, late 26) or transplant (n = 1). Recurrent symptoms following a second re-do CABG required a graft angioplasty (n = 6: early 2, late 4), a subsequent re-do CABG (n = 32) or a transplant (n = 4). Cumulative incidence of cardiac events at 1 month, and 1 and 8 years were: 20, 40.45 and 66.44% following graft angioplasty and 5.5, 10 and 56.55% following a second re-do CABG, respectively (P<0.05). Actuarial survival at 1 month and 6 years following graft angioplasty were 97.15 and 77.22%, and 94.7 and 83.26% after a second re-do CABG, respectively (NS). Re-do CABG was more effective and durable. Graft angioplasty provided a good palliation in suitable cases and also postponed the need for a high-risk surgical intervention for more favorable conditions.

Use of home and community-based services by elderly black and white females.

The study purpose was to determine the impact of demographic, social, environmental, and health indicators on utilization of community-based services among black and white female elders. Existing data from a regional Area Agency on Aging was used and the sample (N = 1816) included low income and rural females. Races differed in use and services most frequently used were case management, outreach, congregate meal, and home delivered meals. Multiple linear and logistic regression indicated that age, payment source, income adequacy, residence, health conditions, sensory impairment, and function were associated with the number and types of services used, but these differed by race. Study findings have implications for health care providers, educators, policy makers, and planners.

Ventricular arrhythmia following successful myocardial revascularization: incidence, predictors and prevention.

OBJECTIVES: We estimated the risk of sudden cardiac death (SCD), from a spontaneous episode of ventricular arrhythmia (VT/VF), after a successful surgical myocardial revascularization (coronary artery bypass grafting; CABG) procedure. Predictors of these events were identified, and long term benefits of the prophylactic regimes, that were used to control these events, were evaluated. METHODS: We selected 8642 consecutive patients, who had undergone an isolated and first time CABG procedure, between 1/3/1980 and 1/3/1995. A standard hazard function model (1) was used for statistical analysis. Efficacy of the prophylactic regimes, was examined in a group of 350 high risk patients, with a preoperative left ventricular ejection fraction 30% or less, who were recently operated since 1/1/1988. Electrophysiologic (EP) guided prophylaxis was used in 92 (26%) patients, who had survived a documented episode of SCD, and remaining 258 patients were maintained on antiarrhythmic medication on an empirical basis. A sequential EP evaluation was performed, when indicated. RESULTS: During an early phase of hazard, which mainly lasted for up to 3 months after CABG, incremental risk factors were preoperative LVEF 30% or less (P = 0.0007) and preoperative episodes of VT/VF (P = 0.04). This phase was followed by a constant phase with a low risk of the events, which merged into a slowly rising late phase after 6 years. EP guided prophylaxis, reduced the risk of SCD in high risk patients (P = 0.03). A sequential EP evaluation, helped to detect the problems of drug resistance and a cross over from non-sustained to sustained runs of VT/VF. CONCLUSIONS: Despite a successful CABG surgery, risk of VT/VF persists. A routine EP evaluation before and after a CABG procedure is recommended in all patients with a poor left ventricular function.

Adult respiratory distress syndrome following cardiopulmonary bypass: incidence, prophylaxis and management.

BACKGROUND: In this retrospective study, we have examined the incidence and the predictors of ARDS (adult respiratory distress syndrome), in patients undergoing coronary artery bypass (CABG) surgery on cardiopulmonary bypass (CPB). The prophylactic and therapeutic measures that were used in this series were also evaluated. METHODS: Between January 1988 and January 1995, 4318 consecutive patients undergoing an isolated and a primary CABG procedure were included. Patients with poor left ventricular function, congestive heart failure (CHF), renal failure and with an abnormal chest radiogram were excluded. RESULTS: The independent predictors of ARDS were: recent cigarette smoking, advanced COPD (chronic obstructive pulmonary disease) and emergency surgery. The overall incidence of ARDS was 2.5% and hospital mortality in patients with an established ARDS was 27.7% (30/108). The prophylactic and the therapeutic measures which have been used in this series had no significant impact on the incidence and hospital mortality. CONCLUSIONS: In view of a high perioperative mortality in patients with established ARDS, a mandate for a regular use of prophylactic and therapeutic measures that are based on its pathophysiology, clearly exists.

Coronary artery bypass grafting in patients with an ejection fraction of twenty percent or less.

Over a 7-year period, 5.8% (n = 210) of patients who underwent coronary artery bypass grafting at our institution had severely impaired global left ventricular function with an ejection fraction of 20% or less. Mean age at operation was 66 years (+/- 0.7; standard error), and 76% of patients were male. Primary indications for operation were unstable angina (73 patients, 35%), return of symptoms with previous bypass grafting (41 patients, 20%), congestive heart failure with reversible ischemia (55 patients, 26%), and recurrent ventricular arrhythmias (41 patients, 20%). Overall, actuarial survival (n = 210) was 82%, 79%, and 73% at 1, 2, and 5 years. Risk of death was highest early after the operation, and then declined rapidly to a constant level. Patients who did not receive retrograde coronary sinus cardioplegia (p = 0.05), older patients (p = 0.004), and those with preoperative ventricular arrhythmias (p = 0.003) or renal failure (p < 0.0001) had an increased risk of death early after operation. Patients with congestive symptoms and those requiring extensive or redo bypass grafting (p = 0.02) were found to be at an increased risk of death throughout the follow-up period. When the number of distal anastomoses performed increased, survival was found to decrease (p < 0.003), and to a greater extent in women than in men (p = 0.02). Of the four primary indications for operation, unstable angina yielded the highest risk-adjusted survival. Successful results after surgical revascularization in patients with severe impairment of ventricular function can be achieved by careful patient selection and management.

Reoperative coronary artery bypass surgery: early and late results and management in 1300 patients.

In this retrospective series overall results after reoperative coronary artery bypass surgery and the subsequent management of recurrent ischemic heart disease in these patients were reviewed. Between September 1980 and September 1993, 17% (n = 1300) of our patients (Pts) undergoing myocardial revascularization (CABG) were reoperative. Of these, 75% were male and 17% were > or = 70 years. One or both internal thoracic arteries (ITA) were used in 25% Pts; a saphenous vein graft (SVG) was used sequentially in 67% or as a separate conduit in 8%. Hospital mortality was higher after redo CABG than after primary CABG (6.9% vs 2.1%, p < 0.0001) and also in Pts receiving SVG rather than IMA as a conduit (7% vs 3.8%, p < 0.001), and in Pts receiving retrograde coronary sinus cardioplegia (RCSC) (n = 504) as compared to those who received antigrade cardioplegia since 1989 (n = 334) (2.5 vs 5.4%, p < 0.05). Throughout the series, independent predictors of hospital mortality by multivariate analysis were: female gender, postoperative myocardial infarction, congestive cardiac failure and stroke. Actuarial survival at 10 years for the patients receiving ITA as a conduit was 86% and for the patients receiving SVG only 76% (p < 0.02); for patients > 70 years was 66% and for patients < 70 years 80% (p < 0.005). Pts with a LVEF < 20% had a poor survival after 2 years. At 10 years cardiac related event free survival after 1st reoperation was 53%. During 13 years 94 Pts underwent subsequent reoperations and 125 Pts underwent saphenous vein graft angioplasty (PTCA), for recurrent ischemic heart disease. Cardiac event free survival at 6 years was clearly superior after multiple reoperative surgery than after graft angioplasty (45% vs 35% p < 0.05). In conclusion, in this series, use of the ITA as a conduit and RCSC has significantly improved Pts survival after redo CABG. Survival and quality of life were further improved in patients requiring multiple reop CABG or graft PTCA.

Coronary artery bypass grafting within 30 days of an acute myocardial infarction.

Risks and benefits of performing coronary artery bypass grafting (CABG) within 30 days of an acute myocardial infarction (AMI) were examined. In 642 patients operated on between January 1988 and December 1993, emergent CABG was performed in 46 patients for cardiogenic shock mainly for failed thrombolysis in patients with an evolving AMI. The remaining patients underwent urgent (< 72 hours) or elective (> 72 hours) revascularization for failed percutaneous transluminal coronary angioplasty (n = 73), postinfarction angina (n = 381), vein graft stenosis (n = 100), and complications after an AMI (n = 42). In patients who underwent primary CABG for an uncomplicated AMI, the infarct was subendocardial in 68, anterolateral or septal in 200, inferior or posteroinferior in 200, and posterolateral in 32 patients. Early mortality (< 30 days) was 5.9% for the entire series and 0%, 4.5%, 4.5%, 29%, 9%, 8%, 10%, and 26% for the subsets of patients with subendocardial infarct, anterolateral or septal infarct, inferior or posteroinferior infarct, ischemic mitral regurgitation, left ventricular aneurysm, redo CABG, age more than 70 years, and left ventricular ejection fraction less than 0.30, respectively. By multivariate analysis, independent predictors of early mortality were left ventricular ejection fraction less than 0.30, age more than 70 years, and cardiogenic shock.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty versus coronary artery bypass in octogenarians.

We retrospectively analyzed early and late results for two treatment strategies of significant coronary artery disease in 310 octogenarians seen in the last 10 years. One hundred five patients 80 or more years of age had percutaneous transluminal coronary angioplasty (PTCA) and 205 had coronary artery bypass grafting (CABG). The PTCA group differed from the CABG group in having a greater proportion of women (71.4% versus 45.8%; p < 0.001); fewer patients with unstable angina (24.7% versus 33.6%; p < 0.04), acute myocardial infarction (11% versus 23%; p < 0.04), three-vessel coronary artery disease (20% versus 56%; p < 0.0001), and a left ventricular ejection fraction less than or equal to 0.30 (10% versus 21%; p < 0.008); and fewer vessels revascularized (1.2 +/- 0.6 versus 3.5 +/- 0.9; p < 0.0001). Hospital mortality was 8.57% after PTCA (9/14 failed PTCA) and 5.8% after CABG (4/14 emergent, 6/101 urgent, and 2/90 elective). Hospital stay was 7 +/- 0.9 days after PTCA and 14 +/- 1.5 days after CABG (p < 0.01). Independent predictors of hospital mortality obtained by multivariate analysis included failed PTCA and acute myocardial infarction (PTCA group), a left ventricular ejection fraction equal to or less than 0.30, and acute myocardial infarction and emergency CABG (CABG group). Survivors after both CABG and PTCA showed a significant improvement in their New York Heart Association class. Actuarial survival at 5 years after PTCA was 55% and after CABG it was 66% (p < 0.01). Cardiac event-free survival (deaths, myocardial infarction, PTCA, CABG) at 3 years was 61% after PTCA and 81% after CABG (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Surgical management in patients with coexistent coronary and cerebrovascular disease. Long-term results.

Between January 1980 and December 1992, 3% (210/6,862) of our patients undergoing myocardial revascularization (CABG) had high grade (> 80%) internal carotid stenosis (CS). One hundred seventy-five of these patients with complete follow up for a minimum of 18 months were studied. Bilateral internal CS was present in 60%, and 75% had other vascular lesions, mainly as peripheral vascular disease (PVD) of the lower limb (50.8%). All patients underwent CAE (carotid endarterectomy) followed by CABG under the same anesthesia. Peripheral vascular lesions, contralateral internal CS and recurrent (n = 43) and progressive vascular lesions (n = 50), were subsequently treated as staged procedures. Hospital mortality was 3.42%. By univariate analysis significant predictors of late mortality were congestive heart failure, COPD, PVD, postoperative myocardial infarction, postoperative stroke, and ischemic cardiomyopathy. Only the latter two were also significant by multivariate analysis. At 12 years, actuarial survival in the presence of these risk factors were 46%, 49%, 22%, 37%, 53%, and 27% respectively. All are significantly lower as compared with the corresponding subsets of patients with the risk factor absent. At 12 years, actuarial survival for the entire series was 65%. Cumulative incidence of postoperative strokes was higher in patients with bilateral internal CS than in patients with unilateral internal CS (p < 0.07) and in patients with neurologic symptoms than asymptomatic patients. At 12 years, actuarial freedom from all cardiac related events, postoperative stroke, and symptomatic PVD were 49%, 82%, and 76% respectively. After successful revascularization these patients should be carefully followed for recurrent and progressive vascular lesions.

Primary malignant pericardial mesothelioma: a case report and review.

Primary malignant pericardial mesothelioma is a rare tumor of unknown etiology. The prognosis is extremely poor due to generally late presentation, inability to completely eradicate it surgically and its poor response to radiotherapy or chemotherapy. An unusual case of pericardial mesothelioma which presented as constrictive pericarditis is described. A comprehensive review of the 140 cases reported in the literature so far is presented to assist the readers in the management and prognosis of this rare, pathological tumor.

Cardiac operations in patients with end-stage renal disease.

Factors influencing the survival of 35 consecutive patients in end-stage renal disease who required 40 open heart surgical procedures over the past 8 years were studied. The mean age in these patients was 57.7 +/- 3 years (range, 32 to 77 years); 74.3% of the patients were male; and the average duration of hemodialysis was 3.6 +/- 0.6 years. Twenty-nine myocardial procedures (20 of 29 for unstable angina), six valve replacements, and five combined procedures were performed. The actuarial survivals at 1 and 3 months, and at 1, 5, and 8 years were 90%, 85%, 76%, 55%, and 43%, respectively. Based on the results of univariate analysis, the most significant predictor of both early and late mortality was New York Heart Association (NYHA) class IV congestive heart failure. The 5-year survival in the patients 60 years and older was less favorable than that in patients younger than 60 years (45% versus 63%) (p < 0.05). The 5-year survival in the patients in NYHA class IV was only 27%, as compared to 63% in the patients in class II or III (p < 0.001). All survivors have remained free of angina and 19 of the 21 survivors showed an improvement in their NYHA class. Four patients under 40 years of age have subsequently been able to undergo renal transplantation. Overall, these results justify proceeding with an open heart surgical procedure in dialysis patients, when needed, but before the onset of congestive heart failure.

Improved myocardial ischemic tolerance by contractile inhibition with 2,3-butanedione monoxime.

Contracture of the arrested myocardium during prolonged storage of the heart results in both systolic and diastolic dysfunction, and is a major limitation to extended preservation. We studied the effects of a reversible contractile inhibitor, 2,3-butanedione monoxime (BDM), on myocardial ischemic tolerance. Isolated rabbit hearts were flushed with University of Wisconsin (UW) solution with and without 30 mmol/L BDM and 1 mmol/L CaCl, stored at 4 degrees C for 24 hours, and subsequently reperfused for 60 minutes. Left ventricular pressure-volume relationships and adenine nucleotide content were determined before reperfusion. Left ventricular systolic pressure, diastolic volume, and adenine nucleotide content were measured after reperfusion. Hearts stored in UW solution underwent contracture and adenosine triphosphate (ATP) depletion during storage, and exhibited systolic dysfunction, impaired diastolic relaxation, and poor ATP regeneration upon reperfusion. The addition of calcium worsened contracture and ATP depletion (p < 0.005) and slightly improved function and ATP regeneration (p = not significant). Hearts stored in the presence of BDM experience no contracture during storage; ATP was preserved (10.7 versus 15.7 nmol/mg; p < 0.05), and left ventricular systolic pressure and ATP content recovered to 74% and 93% of control on reperfusion, respectively (p < 0.005). Left ventricular diastolic volume remained depressed, however, although less than with UW solution (0.87 versus 0.45 mL; p < 0.001). When both BDM and calcium were included in the UW solution, calcium-stimulated ATP hydrolysis and contracture were prevented, left ventricular systolic pressure returned to 87% of control, and left ventricular diastolic volume and ATP content returned to control levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of function, perfusion, metabolism, and histology in hearts preserved with University of Wisconsin solution.

BACKGROUND: University of Wisconsin solution has shown promise for prolonged cardiac preservation. This study compared the effects of 24-hour cold storage and perfusion preservation techniques by assessment of function, perfusion, metabolism, and histological changes. METHODS AND RESULTS: Three groups of rabbit hearts (n = 6 each) were evaluated: 1) control with immediate reperfusion, 2) continuous perfusion preservation, and 3) cold storage. Hearts were reperfused for 30 minutes, and left ventricular systolic pressure (LVSP) was measured by isovolumetric balloon (LVEDP, 20 mm Hg). We used 201Tl to assess perfusion and 14C-acetate to assess metabolism by macroautoradiography. LVSP was similar for controls and hearts preserved with continuous perfusion (134.8 +/- 2.1 versus 112.2 +/- 6.0 mm Hg, respectively). Hearts preserved with cold storage techniques were significantly worse (36.7 +/- 6.0 versus 134.4 +/- 8.2 mm Hg, p < 0.001). Controls showed homogeneous perfusion and metabolism, whereas hearts in the continuous perfusion group showed mild hypoperfusion and histological damage (26.4 +/- 2.7% of left ventricular cross section). Hearts in the cold storage group had 51.7 +/- 1.2% of the left ventricle hypoperfused and damaged. Histology in the control group was normal; in the perfused group, there were only mild changes; and in the cold storage group, there were extensive derangements of cellular architecture. CONCLUSIONS: Continuous perfusion of the heart with 4 degrees C modified University of Wisconsin solution provided function comparable to that of control. Conversely, cold storage showed extremely poor return of function. Autoradiography confirmed mild perfusion and metabolism abnormalities in control and continuous perfusion hearts, whereas there was marked derangement of cellular architecture, perfusion, and metabolism in the cold storage hearts.

Limitations of heart preservation by cold storage.

Clinical heart preservation is currently limited to only 4-6 hr, while the kidney, liver, and pancreas can tolerate 24-48 hr of cold ischemia. A fundamental difference between these organs is that the heart is contractile, containing large quantities of actin and myosin, and is susceptible to contracture-induced injury caused by energy deprivation. We have quantified and correlated the onset of contracture with levels of ATP and glycogen during cold storage in rabbit hearts flushed with UW solution, with and without 1 mM calcium (Ca), or 3 mM iodoacetate (IAA). A fluid-filled left ventricular balloon was used to generate pressure-volume curves (compliance) at 1, 6, 12, 18, and 24 hr of cold storage. Onset of contracture occurred in UW stored hearts at 18 hr, contracture in hearts exposed to Ca occurred between 6 and 12 hr. Compliance was significantly less in hearts exposed to Ca at 12, 18, and 24 hr (P less than .01) than in hearts without Ca. ATP levels were well maintained for up to 18 hr in the hearts preserved in UW solution (78%), but fell more rapidly in the presence of Ca at 12 hr (P less than .005), 18 hr (P less than .005), and 24 hr (P less than .05). In comparison, the ATP supply of the liver and kidney was exhausted by only 4 hr of cold storage. Onset of myocardial contracture correlated with a decrease in ATP to less than 80% of control, and contracture accelerated ATP decline 3-6-fold. IAA caused nearly complete myocardial contracture and ATP depletion within 2 hr. Isolated heart function was 77% and 73% at 6 and 12 hr of storage, but fell to 54% and 42% at 18 and 24 hr, respectively, coinciding with development of contracture. We conclude that ischemic contracture in this model is a major cause of myocardial damage during cold storage, and is accelerated by the presence of Ca. Other organs can be successfully stored despite exhaustion of ATP reserves. Thus successful cold-storage of the heart is highly ATP-dependent. Since cold storage inevitably leads to ATP depletion, extension of myocardial ischemic tolerance will depend on either reversible inhibition of ATP hydrolysis during storage, reversible uncoupling of contracture development from ATP depletion, or maintaining ATP production by continuous hypothermic perfusion.