Tamponade in patients undergoing cardiac surgery: a clinical-echocardiographic diagnosis.

The purpose of this study was to evaluate the sensitivity of current echocardiographic criteria in detecting cardiac tamponade in the patient who has undergone cardiovascular surgery. Because the current echocardiographic criteria for tamponade were initially developed and studied predominantly in patients with medical problems, relatively less information is available in patients who have undergone cardiac surgery. Of 848 consecutive patients who underwent cardiovascular surgery, patients were selected for the study if they had clinical or hemodynamic deterioration and had undergone an echocardiogram just before a successful pericardiocentesis or a surgical evacuation of pericardial blood or clot. The echocardiograms were evaluated for evidence of chamber collapse, cardiac motion, Doppler flow variations, and the location and width of pericardial separation. Fourteen patients were identified who met the inclusion criteria (clinical or hemodynamic deterioration, recent echocardiogram, and successful intervention) for cardiac tamponade. The clinical and hemodynamic findings were hypotension (13 patients), low cardiac output (7), low urine output (3), cardiopulmonary arrest (1), elevated central venous pressure (1), and shortness of breath (1). In these patients current echocardiographic criteria were seen infrequently: chamber collapse in the right atrium (6 of 14 patients) and right ventricle (4 of 14); Doppler flow variation (2 of 5); and swinging heart (0 of 15), whereas increased pericardial separation (> or = 10 mm) was seen in all (14 of 14) the patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Incomplete recovery of working heart function after twenty-four-hour preservation with a modified University of Wisconsin solution.

BACKGROUND AND METHODS: This study was designed to determine the function of isolated rabbit hearts after static preservation with modified University of Wisconsin solution for 24 hours. Commercially available University of Wisconsin solution, modified with CaCl2 1 mmol/L and 2,3-butanedione monoxime 30 mmol/L, was used as the preservative. After flushing the coronary vasculature with medium, hearts were submersion stored at 1 degree C to 4 degrees C. After preservation, isolated heart function at 37 degrees C was quantified for 30 minutes in a non-ejecting mode and for 4 hours ejecting at a physiologic workload. Fresh control hearts (n = 5) and University of Wisconsin solution-preserved hearts (n = 6) were studied. RESULTS: Nonworking (non-ejecting) left ventricular function of the two groups did not differ, except for peak rate of left ventricular pressure development which was higher for the University of Wisconsin solution hearts than for controls. When the hearts were subjected to a physiologic workload, however, left ventricular function of the two groups differed significantly. Three of the six University of Wisconsin solution hearts failed before the 4-hour perfusion end point, whereas all five control hearts maintained stable working function for the full 4 hours. The University of Wisconsin solution hearts, while in the ejecting mode, exhibited significantly impaired function. Mean values were as follows (p < 0.05): left ventricular systolic pressure (in millimeters of mercury), control 105 +/- 1, University of Wisconsin solution 86 +/- 4; peak rate of left ventricular pressure development (in millimeters of mercury per millisecond), control 3.33 +/- 0.11, University of Wisconsin solution 2.39 +/- 0.24; cardiac output (in milliliters per minute per gram), control 400 +/- 25, University of Wisconsin solution 288 +/- 26; stroke work (in milliJoules per gram), control 20.1 +/- 1.3, University of Wisconsin solution 11.9 +/- 1.1; left ventricular end-diastolic pressure (in millimeters of mercury), control 5.4 +/- 0.3, University of Wisconsin solution 10.2 +/- 1.3; peak aortic flow rate (in milliliters per minute), control 946 +/- 9, University of Wisconsin solution 659 +/- 44; millimoles of lactate produced in 30 min/Joule stroke work, control 0.50 +/- 0.06, University of Wisconsin solution 6.99 +/- 0.37. CONCLUSIONS: These results indicate that (1) hypothermic storage in this modified University of Wisconsin solution does not preserve hearts sufficiently to support a physiologic workload for an extended period and (2) assessment of post-preservation function with a non-ejecting heart model does not accurately predict the ability of the preserved heart to support a physiologic workload.

Advantages of continuous noncardioplegic warm blood retrograde perfusion over antegrade perfusion during proximal coronary anastomoses.

Retrograde perfusion via the coronary sinus supplies vascular beds distal to coronary stenoses and has been used for administration of cardioplegia. An additional application is to supply noncardioplegic retrograde perfusion while performing proximal anastomoses (a time when cardiac arrest is not critical). The aim of this study was to determine the safety of this technique and to study the metabolic changes with antegrade versus retrograde warm blood perfusion. Sixty-six patients, with good left ventricular function, underwent distal coronary bypass in a similar fashion. Proximal anastomoses were done with 1) partial occlusion clamp (n = 29) or 2) cross-clamp on and continuous, warm, noncardioplegic retrograde blood perfusion (n = 37). In an additional 10 patients, metabolism was assessed with antegrade and retrograde perfusion during proximal anastomoses. Despite longer cross-clamp times (96.4 +/- 6.2 vs 80.8 +/- 3.1 min, p < 0.05) with retrograde perfusion, the total duration of cardiopulmonary bypass was significantly less (119.6 +/- 6.2 vs 136.6 +/- 4.6 min, p < 0.05). There was superior postbypass, intraoperative hemodynamics (cardiac index) with retrograde perfusion (4.0 +/- 0.2 vs 3.6 +/- 0.1 L/min/m2). The incidence of postoperative dysrhythmia was not significantly different between groups. Oxygen and glucose utilization was more efficient with retrograde perfusion. Retrograde perfusion during proximal anastomoses is a safe technique. There is diminished risk of aortic dissection, atheroembolism, delayed aneurysm formation, or rupture due to avoidance of application of partial occlusion clamps. There is evidence of superior substrate utilization.

Poststernotomy fractures and pain management in open cardiac surgery.

STUDY OBJECTIVES: To assess whether (1) there is an increased incidence of sternal fractures associated with internal mammary artery (IMA) revascularization in open heart surgery and (2) there is a higher incidence of pain in postoperative patients with sternal fractures. METHODS: Two hundred eighty-eight consecutive adult patients who had undergone cardiac surgery underwent median sternotomy from 1989 to 1991. IMA revascularization was used in 94 patients. The remainder underwent conventional saphenous vein graft (SVG) revascularization or other open cardiac procedure. The sternum was checked for fracture at the time of chest-wall closure. Lung volumes, arterial blood gases, respiratory rate, and oxygen requirements were measured before and after pain relief by intravenous or epidural analgesia. RESULTS: Of 288 consecutive median sternotomies, there were a total of 24 sternal fractures. IMA harvesting was associated with a significantly greater incidence of sternal fractures. In the 94 patients in whom IMA mobilization was used, there were 16 fractures; in the remaining 194 cases, there were 8 fractures (p < 0.007). Twenty-one of 24 patients were not seriously affected by their sternal fractures, whereas 3 patients suffered major respiratory compromise due to postoperative pain. Epidural analgesia was effective treatment for these three cases of severe sternal fracture pain and was not associated with any adverse consequences. All three patients had significant improvement in their respiratory condition after epidural analgesia was instituted. Respiratory rate decreased from 27 +/- 3 to 18 +/- 0.3 breaths/min (p < 0.001) and end maximum inspired volume increased from 700 +/- 1 mL to 1,525 +/- 275 mL. CONCLUSIONS: The use of sternal retraction devices for IMA harvesting in coronary bypass procedures results in an increased incidence of sternal fractures when compared with conventional SVG bypass procedures. Although most sternal fractures are well tolerated, some patients with fractures can become a significant pain management problems. Epidural analgesia is a safe and effective treatment for severe pain associated with sternal fractures and provided improved postoperative pulmonary function.

Improved myocardial function using cardiopulmonary support in resuscitation for hemorrhagic shock.

OBJECTIVES: To clarify the pathophysiologic characteristics of hemorrhagic shock and to assess methods of resuscitation. DESIGN: An animal experiment using sheep subjected to hemorrhagic shock and fibrillation to compare various resuscitation techniques. SETTING: An experimental laboratory setting meant to simulate hemorrhagic shock secondary to trauma. STUDY GROUPS: Group 1 animals (n = 6) were controls that were not subjected to shock and fibrillation. Group 2 animals (n = 6) were subjected to shock and fibrillation and were resuscitated with volume replacement. Group 3 animals (n = 6) were also subjected to shock and fibrillation but were resuscitated with epinephrine hydrochloride infusion. Group 4 animals (n = 6) were subjected to shock and fibrillation but were resuscitated with cardiopulmonary support. INTERVENTIONS: The shock was to a mean arterial pressure of 25 mm Hg for 1 hour followed by 5 minutes of fibrillation. Group 2 animals were resuscitated for 1 hour. Group 3 animals were supported for 6 hours on epinephrine after the shock period. Group 4 animals were supported for 1 hour on cardiopulmonary support, then were observed for another 5 hours. All animals were sedated and intubated, and a median sternotomy was performed. MAIN OUTCOMES MEASURED: Survival, hemodynamic function, lactate production, myocardial blood flow, and water content. RESULTS: Group 1 sheep showed no detrimental effects in any of the measured variables. Group 2 sheep could not be resuscitated. Group 3 sheep could be supported with epinephrine but had a 60% depression in left ventricular function and an ultimately high mortality rate (67%) when the infusion of epinephrine was discontinued. Group 4 sheep had a 100% survival rate and only a 20% deterioration in left ventricular function. CONCLUSIONS: Cardiopulmonary support improves survival and preserves left ventricular function compared with volume resuscitation with or without inotropic support in this model of hemorrhagic shock.

Use of Carmeda-coated femoral-femoral bypass during repair of traumatic aortic pseudoaneurysms.

OBJECTIVE: To compare the results and outcomes of three different approaches to posttraumatic pseudoaneurysm repair: clamp and sew, left heart bypass, and the most recent approach, cardiopulmonary support using femoral-femoral bypass. DESIGN: Retrospective series. SETTING: A university-based, level 1 trauma center. PATIENTS: Forty-two consecutive patients treated for posttraumatic aortic pseudoaneurysm whose mean (+/- SEM) Injury Severity Score was 37 +/- 1.7. INTERVENTION: Methods of repair included clamp and sew in nine patients, left heart bypass in 24 patients, and cardiopulmonary support in nine patients. METHODS: Student's t test was used to compare interoperative blood loss, need for blood transfusion, and aortic cross-clamp time. Complications and mortality were also reviewed. RESULTS: Mean (+/- SEM) aortic cross-clamp time for clamp and sew was 28.1 +/- 3.3 minutes vs 52.5 +/- 3.7 for left heart bypass and 49.3 +/- 5.6 for cardiopulmonary support. Blood loss and the need for transfusion were comparable between groups. Complications were also comparable. CONCLUSION: Femoral-femoral cardiopulmonary support is safe to use, has a very low risk of complications, and should provide protection for the spinal cord during aortic repair. We encourage a randomized prospective trial to determine if cardiopulmonary support has a significantly lower rate of paraplegia than the clamp- and -sew technique.

Posttransplantation function of hearts preserved with fluorochemical emulsion.

This study was designed to determine whether the novel perfluoroperhydrophenanthrene-egg yolk phospholipid emulsion, APE-LM, was an effective oxygen carrier for long-term hypothermic heart preservation. We postulated that hearts preserved with APE-LM would be well oxygenated during 24-hour preservation and that reperfusion of such hearts with blood would not produce functional or metabolic evidence of myocardial ischemia. Four groups of rabbit hearts were studied (n = 7 per group): fresh controls: nonpreserved, nontransplanted hearts; surgical controls: fresh hearts transplanted heterotopically for 75 minutes before explant and study for 4 hours as isolated working hearts perfused at 37 degrees C; crystalloid-preserved: hearts preserved with crystalloid medium, followed by transplantation and isolated heart perfusion; APE-LM-preserved: hearts treated as those in the crystalloid-preserved group, but preservation was with medium containing APE-LM emulsion (10 ml/dl). Preservation was with continuous coronary perfusion at 18 mm Hg pressure, 12 degrees C, and oxygen tension 838 +/- 11 mm Hg. During preservation, APE-LM hearts had significantly higher pyruvate consumption, and correspondingly higher oxygen consumption, than that of crystalloid hearts. No significant differences were found among fresh controls, surgical controls, and APE-LM-preserved hearts with respect to contractile or output function, oxygen consumption and efficiency indexes, or lactate production during in vitro perfusion. Left ventricular peak systolic pressure and peak rate of pressure development were significantly lower for crystalloid-preserved hearts than for fresh and surgical controls. Left ventricular end-diastolic pressure of crystalloid-preserved hearts was higher than that of the other three groups. The data indicate that rabbit hearts in this model were well preserved with APE-LM and that this emulsion produced better recovery of function than did crystalloid preservation, possibly as a consequence of the high oxygen delivery by the fluorocarbon during preservation.

Balloon mitral valvulotomy as a bridge to valve replacement.

Balloon mitral valvulotomy is used in treating mitral stenosis. We stabilized a near-moribund patient who had combined aortic and mitral valve stenoses with this technique on an emergency basis. Following valvulotomy, mitral valve area increased from 1.1 to 2.2 cm2, pulmonary capillary wedge pressure decreased from 31 to 21 mmHg, and cardiac index increased from 1.9 to 2.8 L/min/m2. When the patient's condition improved, we replaced the aortic and mitral valves with St. Jude Medical bileaflet prostheses. Balloon mitral valvulotomy has not been previously described as a "bridge" to operation. The patient in this report was at extremely high risk with cardiopulmonary and hepatorenal failure, and is the first where valvulotomy was used as temporary rather than definitive management. It should be considered only in cases without calcified, fibrotic valves and where the operative risk is considered prohibitive.

Cardiopulmonary bypass used in the resuscitation of eventual organ donors: a case report.

Little has been published regarding cardiopulmonary bypass in the resuscitation of eventual organ donors. One such pediatric donor at our institution provided organs, which have thus far been successful. Pediatric organs have demonstrated usefulness, even when transplanted into adult recipients. Further research will provide data on the utility of organs obtained after cardiopulmonary bypass resuscitation.

Importance of substrate enhancement for long-term heart preservation.

These experiments tested the hypothesis that addition of pyruvate to a preservation medium would improve postpreservation cardiac function as quantified in an isolated working heart model after heterotopic transplantation. Four groups of rabbit hearts were studied (n = 5 per group): fresh controls, fresh hearts perfused as isolated working hearts; surgical controls, fresh hearts transplanted heterotopically and reperfused with blood for 75 minutes before being studied as isolated hearts; preserved without pyruvate, hearts perfusion-preserved with oxygenated extracellular-type crystalloid medium; preserved with pyruvate, same same as the group without pyruvate, but medium contained 20 mmol/L pyruvate. After preservation, the hearts in the two preserved groups were transplanted and studied as isolated hearts. Total ex vivo time for the preserved hearts was 24.5 +/- 0.2 hours. During preservation, glucose was not consumed by hearts in either preserved group. Pyruvate was used by the hearts to which it was provided (22.9 +/- 2.7 mumol pyruvate x hour-1 x gm dry weight-1). Performance of transplanted surgical control hearts was not significantly different from that of fresh controls. Function of the pyruvate-preserved hearts was similar to that of the fresh and surgical controls except that left ventricular peak systolic pressure and peak rate of pressure development were lower and that left ventricular end-diastolic pressure was higher for the pyruvate-preserved hearts. The hearts preserved without pyruvate had significantly lower compliance and function compared to the other three groups, which was evident in all indexes of contractility and output. We conclude that hearts preserved with pyruvate-containing crystalloid medium had better postpreservation, posttransplantation function than hearts preserved without pyruvate, although there was slight loss of compliance and decreased contractile function in the pyruvate-preserved hearts compared to controls.

Pericardial patch repair of left ventricular aneurysm.

Infectious complications associated with the use of Teflon felt buttresses in left ventricular aneurysm repair may result in serious morbidity. Use of an autologous pericardial patch is an alternative approach that should be considered. The technique, which we have used in 4 patients, is described.

Use of a heat exchanger to prevent hypothermia during thoracic and thoracoabdominal aneurysm repairs.

Hypothermia is a common unplanned occurrence in many patients undergoing repair of thoracic and thoracoabdominal aneurysms. Many undesirable side effects of hypothermia have been documented, including decreased cardiac output, conduction abnormalities, and blood coagulopathies. We have developed a simple system that incorporates a Sci-Med Biotherm heat exchanger into our left heart bypass circuit. This provides us with the ability to actively rewarm the patient safely and efficiently. This study looks at 16 consecutive patients undergoing repair of thoracic or thoracoabdominal aneurysms. In the 9 patients in whom the heat exchanger was used, there were no adverse effects related to the heat exchanger. All patients had significantly higher temperatures at the conclusion of the procedure than the 7 patients in whom the heat exchanger was not used.

Inhibition of Na-Ca exchange by general anesthetics.

General anesthetics, typically octanol, were found to inhibit the influx of calcium in isolated sodium-loaded adult rat heart cells, using 45Ca, quin 2, or indo 1. Inhibition by octanol, like inhibition by sodium, was competitive with calcium. Octanol and sodium together inhibited calcium influx synergistically. At physiological levels of extracellular calcium and sodium, the EC50 was 177 +/- 37 microM for octanol and 48 +/- 5 microM for decanol. These values are threefold to fourfold larger than those reported to cause 50% loss of righting reflex in tadpoles, a measure of their anesthetic effectiveness. We conclude that general anesthetics inhibit Na-Ca exchange at the sarcolemma. We suggest that octanol inhibits like sodium, and the synergism stems from the cooperativity of sodium inhibition at the binding and regulatory sites of the exchanger. Insofar as Na-Ca exchange may regulate inotropy, the inhibition of Na-Ca exchange by general anesthetics could contribute to their negative inotropic effect.

Inhibition of ATP-sensitive potassium channels of adult rat heart cells by antiarrhythmic drugs.

We have investigated the effect of antiarrhythmic drugs on the increased potassium conductance induced in isolated adult rat heart cells by ATP depletion. The rate of 86Rb uptake in the presence of ouabain was used as a measure of potassium conductance. Treatment of cells with rotenone plus p-trifluoromethoxyphenylhydrazone (FCCP) rapidly depleted ATP levels and strongly stimulated the rate of 86Rb uptake. The stimulated uptake and the ATP depletion were inhibited by oligomycin; thus, the uptake was not induced by rotenone plus FCCP directly. The stimulated uptake, but not the ATP depletion, was inhibited potently by glyburide (IC50, 38.3 nM), quinidine (IC50, 2.7 microM), verapamil (IC50, 4.5 microM), and amiodarone (IC50, 19.1 microM). The stimulated uptake was also inhibited by tetraethylammonium ion and by 4-aminopyridine but not by tetrodotoxin or manganese. We conclude that 1) the stimulated 86Rb uptake is measuring ATP-sensitive potassium channel activity, 2) the ATP-sensitive potassium channel is strongly inhibited by quinidine, verapamil, and amiodarone, and 3) this inhibition may contribute to the antiarrhythmic action of these drugs.

Measurement of Ca channel activity of isolated adult rat heart cells using 54Mn.

Isolated adult rat heart cells incubated with 5 microM Mn in a medium with 1 mM Ca showed a rapid phase of Mn binding plus a slow phase of Mn uptake. The rapid phase was extracellular binding, as judged by its temperature-insensitive removal by ethylene glycol bis(beta-aminoethyl ether) N, N'-tetraacetic acid. The slow linear phase represented cellular uptake, as judged by its release with digitonin plus the ionophore A23187. Isoproterenol increased the linear rate of Mn uptake and induced spontaneous beating activity in some cells. Both effects were inhibited by nitrendipine. Electrical stimulation of the cells in suspension increased the linear rate of cellular Mn uptake. The increase was potentiated by isoproterenol, and inhibited by nitrendipine or verapamil. Stimulation-dependent Mn uptake (per milligram protein) was greater for cells from 5- to 6-week-old rats than for 8- to 9-month-old female retired breeder rats, in the presence of isoproterenol. Ryanodine increased the stimulation-dependent Mn uptake in the presence of isoproterenol, but not in its absence. We conclude: (i) that cellular uptake of 54 Mn is a good probe of Ca channel function; (ii) that isoproterenol promotes Mn influx by the channel in isolated heart cells; (iii) that cells from young rats (5-6 weeks) have a higher beta-adrenergically induced Ca channel activity than cells from mature rats (8-9 months); and (iv) that ryanodine promotes Ca channel activity (perhaps indirectly) in the presence of isoproterenol.

Some determinants of quality and yield in the isolation of adult heart cells from rat.

We investigated the effect of changes in perfusate substrate and Ca content on the quality and yield of isolated adult rat heart cells. When 1 mM Ca was added to the recirculating perfusate 15 min after collagenase addition, the ATP level of cells in the heart 15 min later, and their morphology in histological section, was no different from when no Ca was added back. The cells subsequently isolated were of similar yield, but a greater percentage were rod-shaped, compared with cells isolated without Ca restoration to the perfusate. Increased yield could be obtained by including substrates in the perfusate in addition to glucose. Either fatty acids or amino acids were effective. We conclude that: (1) all cells in the heart are Ca tolerant at the end of enzyme perfusion; (2) the presence of substrates in addition to glucose can help cells survive the isolation process.

Improved heart preservation with UW preservation solution.

Despite the good clinical results obtained with the current heart preservation techniques, these methods need to be improved. The UW solution has provided excellent preservation for the pancreas, kidney, and liver after extended cold ischemic storage times. We have tested the ability of the UW solution to store hearts for 5 and 12 hours and compared the results with those obtained from hearts preserved by either Stanford or modified Collins' solutions. Three groups of five canine hearts each underwent 5 hours, and three groups of five canine hearts underwent 12 hours of ischemia at 4 degrees C. Then the hearts were reperfused in an isolated working canine heart preparation. Those hearts preserved for 5 hours had nearly normal ventricular function and adenosine triphosphate contents and were able to maintain normal tissue electrolyte concentration and water contents. After 12 hours of storage time only adenosine triphosphate contents were similar among the groups. Hearts preserved with the UW solution rapidly recovered, reaching nearly normal left ventricular function by 60 minutes of reperfusion; hearts preserved by the modified Collins' solution recovered more slowly, but function was good after 120 minutes of reperfusion. Hearts preserved by the Stanford solution never attained adequate function. The three groups of hearts preserved for 12 hours did not differ in their ability to utilize lactate or in their rates of oxygen utilization. Tissue water and sodium contents were considerably lower in the hearts preserved with the UW solution after 150 minutes of reperfusion compared with hearts stored in the modified Collins' or Stanford solutions. Hearts stored 12 hours in the UW solution under cold ischemic conditions recovered left ventricular function rapidly after reperfusion with normal blood, utilized lactate and oxygen at normal rates, and were able to regulate tissue water and sodium contents to nearly normal levels. Because of the superior preservation obtained by the UW solution, the solution deserves further evaluation for possible future use in clinical heart transplant programs.