Effects of varied cardioplegic perfusion pressure on myocardial preservation with critical coronary stenosis

Inadequate delivery of cardioplegic solution distal to coronary artery stenosis may result in increased injury during ischemic arrest. This study was performed to determine the effects of cardioplegic perfusion pressure on cardioplegia delivery and myocardial preservation in hearts with critical coronary artery stenosis. Twenty dogs underwent 90 minutes of cold potassium cardioplegic arrest with partial occlusion of the circumflex coronary artery. Group 1 received cardioplegia at 50 mm Hg pressure, Group 2 at 90 mm Hg pressure, and Group 3 at 130 mm Hg pressure. It was found that cooling rates were 5.4 degrees, 9.1 degrees, and 18.2 degrees C per minute in the nonischemic area (p = 0.004) and 2.0 degrees, 4.5 degrees, and 7.9 degrees C in the ischemic area (p = 0.008) in Groups 1, 2, and 3, respectively. Total of cardioplegic solution flows were 86, 188, and 262 ml per minute per 100 gm in Groups 1, 2, and 3, respectively (p = 0.001). However, flow did not differ significantly between groups in the ischemic area. Rate of rise of left ventricular (LV) pressure decreased significantly in Groups 1 and 2 but not in Group 3 (p = 0.002). Other measured variables did not differ significantly between groups, although LV function curves showed less deterioration in the high-pressure groups. It is concluded that higher cardioplegic perfusion pressure resulted in more rapid cooling in normal and ischemic areas and slightly better preservation of ventricular function as measured by some indexes. However, preservation was generally good for each of the pressures for up to 90 minutes of ischemia when the septum was consistently cooled to 10 degrees C.     

Effects of Morphine and Halothane Anesthesia on Coronary Blood Flow

This study was undertaken to determine the relative effects of morphine and halothane anesthesia on coronary blood flow. Right heart bypass was instituted in 20 dogs by draining the vena cava blood into a cardiotomy reservoir and returning it to the main pulmonary artery. Coronary sinus drainage was measured by a right ventricular cannula. Group I (10 dogs) was sequentially given 0.5, 1, 1.5, 2.0, and 2.5% halothane. Group II (10 dogs) was given 1, 2, 3, 4, and 5 mg per kilogram of morphine intravenously. Arterial pressure, coronary sinus blood flow, cardiac output, arterial pH, Pco₂, and Po₂ were determined and repeated at each dose level of anesthesia and compared to the control values.Morphine significantly increased coronary flow at 3, 4, and 5 mg/kg without pressure adjustment and at 2 mg/kg after pressure adjustment. Coronary flow with halothane was unchanged from control values except for a decrease at 2.5%. Coronary flow was significantly greater with 3, 4, and 5 mg/kg of morphine than with 1.0 and 1.5% halothane.     

Experimental evaluation of reexpansion pulmonary edema

Reexpansion pulmonary edema following pneumothorax is clinically uncommon but occasionally life threatening. This study documents the functional and anatomical abnormalities that occur when a collapsed lung is reexpanded. Right pneumothorax was created through open tube thoracostomy in 30 goats. The animals were divided into six groups by duration of pneumothorax (24, 48, or 72 hours) and technique of reexpansion (waterseal vs 10 cm H2O suction). Arterial blood gases and alveolar-arterial oxygen tension difference (A-aDO2) were analyzed before pneumothorax and after reexpansion. Each lung was reexpanded for 2 hours, chest roentgenograms were obtained, and both lungs were removed. The left lung served as the control. Both lungs were checked for surfactant activity and pulmonary extravascular water volume (PEWY). Light and electron microscopy were also performed. Anatomical and functional changes were present in the reexpanded lung after relief of pneumothorax. Both increased time of collapse and suction reexpansion tended to correlate with increased PEWV, decreased surfactant and arterial PO2, and increased A-aDO2.     

Porcine Valve Bioprosthesis: Early Thrombosis with Systemic Emboli

We report the case of a patient who had early postoperative thrombosis, with systemic emboli, of an aortic Hancock porcine valve bioprosthesis. Anticoagulants were not used postoperatively because the patient had a history of epistaxis. Progressive symptoms and a 57 mm Hg transvalvular gradient prompted reoperation at six months. Thrombosis of the valve may have been related to postoperative low cardiac output, prolonged dysrhythmias, or lack of anticoagulants.     

Does Cardioplegic Arrest Compromise Long-Term Left Ventricular Function?

This study was undertaken to evaluate the chronic, long-term effect of global ischemia produced by cold potassium cardioplegia during cardiopulmonary bypass. Fifteen dogs underwent either control thoracotomy and chronic instrumentation (Group A) or cardiopulmonary bypass and 60 minutes of cold cardioplegic arrest (Group B). With the dogs conscious, hemodynamic variables and left ventricular studies were recorded weekly for 12 weeks postoperatively, both at rest and during volume overload with saline solution. At rest, the heart rate in Group B was 18% higher and stroke volume was 14% lower than Group A. With volume overload, cardiac output and maximum rate of rise of left ventricular pressure in Group B rose only from 3.7 ± 0.6 to 7.1 ± 0.8 liters per minute and 2,410 ± 220 to 2,730 ± 130 mm Hg per second, respectively, compared with 3.9 ± 0.6 to 10.4 ± 0.8 liters per minute and 2,740 ± 230 to 3,890 ± 350 mm Hg, respectively, in Group A (p < 0.01). In Group B, the other variables reached a plateau sooner than in Group A (48 versus 110 seconds). The left ventricular function curve showed a mild decrease in functional capacity and depressed contractility. Therefore, one hour of cardioplegic cardiac arrest caused no depression of function at rest. Mild depression of left ventricular function was demonstrated up to 7 weeks postoperatively during acute volume overload.     

Is a Left Ventricular Vent Necessary During Cardiopulmonary Bypass?

This study evaluated the coronary flow and the internal diameter, pressure, and metabolism of the left ventricle using four different cardiopulmonary bypass techniques. Conditioned dogs underwent a 30-minute stabilizing period on cardiopulmonary bypass with a beating, empty heart (normothermia and a flow of 80 ml/kg/min). They were then fibrillated and subjected to four experiments: Group A (7 dogs)--left ventricular vent, caval tapes open; group B (7 dogs)--left ventricular vent, caval tapes closed; group C (7 dogs)--no vent, caval tapes open; group D (4 dogs)--no vent, caval tapes closed. There was no major difference in any of these variables among Groups A and B (both ventricles vented). Group D (no vent, tapes closed) had significantly increased wall tension, decreased coronary flow, decreased subendocardiac flow, and ischemia. In contrast, Group C dogs (no vent, tapes open) had only a slight increase in left ventricular diameter and pressure, with no change from Group A and B dogs in coronary flow, lactate extraction, hydrogen ion production, or potassium difference. Therefore, venting the fibrillating ventricle, either with or without snaring of the caval tapes, is probably the best method to use during the distal anastomosis in a coronary artery bypass operation. However, if a vent is not used, the caval tapes should be left open to allow complete diversion of the venous blood and decompression of the left ventricle.     

Subxiphoid Pericardial Window in Patients with Suspected Traumatic Pericardial Tamponade

The technique, indications, and results of subxiphoid pericardial window in penetrating chest wounds with suspected traumatic pericardial tamponade are reported.The classic signs of pericardial tamponade (elevated central venous pressure, muffled heart sounds, and paradoxical pulse) are unreliable in an emergency situation. Chest roentgenograms and electrocardiograms are of little diagnostic value. Pericar-dicentesis was either falsely positive or negative in 50% of our patients. Therefore, unexplainedhigh central venous pressure and hypotension were considered to be pericardial tamponade until disproved by the results of a subxiphoid pericardial window.There were 4 negative and 46 positive findings of tamponade in 50 consecutive patients with suspected traumatic pericardial tamponade who underwent creation of a subxiphoid pericardial window. There were no deaths or complications from the procedure. The early use of subxiphoid pericardial window has been a major factor in reducing our mortality rate from penetrating heart wounds to 12% overall, and 8% in the past three years.     

Prosthesis for Correction of Single Ventricle

A prosthetic right ventricular conduit that may be applicable in repair of the single ventricle anomaly is reported. The final conduit evolved from a series of animal experiments, which are described.     

Posttraumatic Empyema

This is a report of the experience gained from treating 18 patients with posttraumatic empyema during a 36-month period. The objectives of treatment were twofold: complete reexpansion of the lung, and evacuation of infected foreign material from the pleural space. The techniques of achieving these objectives were tube thoracostomy initially, followed by early thoracotomy if necessary.     

Effect of therapeutic-dose irradiation on left ventricular function in conscious dogs.

Every week, 8 conscious, chronically instrumented dogs underwent left ventricular (LV) function studies before, during, and after cardiac irradiation with cobalt 60 (myocardial dose of 5,000 rads at 200 rads per day through a 5 X 5 cm port). During the weekly LV function studies, left atrial pressures were raised by rapid infusion of balanced saline solution. Heart rate, aortic pressures, left and right atrial pressures, LV pressure, left ventricular end-diastolic pressure (LVEDP), and maximum rate of rise of LV pressure were recorded. Electrocardiograms were made. Cardiac outputs were obtained by thermodilution. Stroke volume, LV stroke work, and LV minute work were calculated. LV function curves were constructed each week. All dogs lost weight and became irritable after approximately 800 rads. The electrocardiograms showed signs of myocardial injury after 1,200 rads. All variables were slightly depressed during the first 8 weeks following irradiation. At the eleventh week, both left atrial pressure and LVEDP increased significantly and LV function declined. There was also clinical evidence of LV failure at rest and after volume loading. This study documents that external cardiac irradiation, in a therapeutic dose and schedule range, causes depression of LV function. These functional changes were partially reversed when the follow-up study was continued to six months after irradiation.     

Subxiphoid Anterior Mediastinal Exploration

A new surgical technique for anterior mediastinal exploration is described. The technique involves application of a Carlens mediastinoscope by means of a subxiphoid incision. The procedure provides complete exploration of the anterior mediastinal compartment and allows the surgeon to obtain a positive biopsy of the tumor or its lymph node metastases without sternotomy.     

Management of the wounded heart

Forty-five patients underwent operation for wounds which had penetrated the pericardium. The preoperative diagnosis was cardiac tamponade in 36 patients and hemorrhagic shock in 9. Cardiac tamponade was often difficult to diagnose—the paradoxical pulse was not clinically useful, and central venous pressure frequently was falsely elevated. Pericardiocentesis was performed in 18 patients with 7 false-negative and 3 false-positive results. A preliminary subxiphoid pericardial window was done in 21 patients. Technical adjuncts included inflow occlusion, electrical fibrillation, partially occluding clamps, and stabilizing traction sutures. Cardiopulmonary bypass was not used. The current incision of preference is a median sternotomy to allow a preliminary subxiphoid pericardial window to be performed in patients with tamponade and a thoracotomy if there is massive bleeding into the pleura.     

Transthoracic Approach for Pott's Disease

Spinal tuberculosis with paraplegia, although decreasing in incidence, remains a problem in certain sections of the United States and in most underdeveloped nations. Evacuation of the tuberculous abscess, debridement of necrotic bone, and fusion of the anterior spine are maneuvers performed increasingly by thoracic surgeons. Twenty-two patients with Pott's disease and symptoms of back pain, gibbous deformity, and neurological deficit underwent thoracotomy. Nine were paraplegic prior to operation. Postoperatively, spinal fusion occurred in all cases. All paraplegic patients can walk now, and 17 of the 22 treated operatively have been completely rehabilitated and are in school or working. The average hospital stay was 2.4 months. There was 1 operative death. Medical treatment for Pott's disease consisted of bed rest and chemotherapy and resulted in progressive neurological deficit in 2 patients with an average hospital stay of 2.2 years.We believe operative treatment offers two distinct advantages: excellent reversal of even long-standing paraplegia and markedly shortened hospital stay.     

Management of flail chest without mechanical ventilation.

The pathophysiology of flail chest is usually described only on the basis of paradoxical respiration, ignoring underlying pulmonary contusion. Two groups of comparable patients were treated either with early tracheal intubation and mechanical ventilation (Group 1), or with fluid restriction, diuretics, methylpredinisolone, albumin, vigorous pulmonary toilet, and intercostal nerve blocks, ignoring the paradox and treating only the underlying lung (Group 2). When tracheostomy and mechanical ventilation were not used the mortality rate went from 21% to O(p = 0.01), the complication rate from 100% to 20% (p = 0.005), and the average hospitalization from 31.3 to 9.3 days (p = 0.005). We conclude that most patients with flail chest do not need internal pneumatic stabilization if the underlying lung is treated appropriately and that tracheostomy and prolonged mechanical ventilation with a volume respirator, as practiced in most respiratory care centers, is usually a triumph of technique over judgment.     

Intravenous catheter emboli. Experience with twenty cases and collective review

From 1969 to 1973 twenty patients at the Bexar County Hospital have had central venous catheter emboli. Sixteen underwent catheter removal, and four did not and were followed up from nine months to six years. There were no significant complications or related deaths in either group. Over 200 cases in the literature were reviewed, and in contrast to our series a 24 per cent mortality for catheter emboli not removed was reported.     

Pulmonary contusion. Pathogenesis and effect of various resuscitative measures

Pulmonary contusion (PC) was induced in anesthetized dogs by firing a .38 caliber blank cartridge against the chest wall. Studies of blood gases, lesion size, lung weight, and microscopical appearance were performed. Various forms of therapy which are commonly used in trauma victims were evaluated. The following conclusions were reached: untreated PC is not progressive; mechanical ventilation and furosemide therapy decrease the severity of the pulmonary lesion; administration of low-molecular-weight dextran and lactated Ringer's solution increases the anatomical and physiological lesion; and central venous pressure is not an accurate index of crystalloid overload. The contused lung is very sensitive to administration of noncolloid fluids.     

Penetrating injuries to the neck. Pitfalls in management.

One hundred patients with penetrating injuries to the neck were evaluated. The safest, most expeditious method of managing a penetrating injury to the neck is still prompt surgical exploration. Patients with positive physical examination have definite indications for surgerymin our series, 93 per cent of these patients had significant injuries. Patients with negative physical examinations are still optimally treated with neck explorations. The mortality of this series was 2 per cent. In specific situations, nonoperative management of penetrating injuries to the neck may be useful. This modality, however; should not be construed as "conservative" management. Specific pitfalls noted include inadequate neck exploration, failure to completely examine the patient, and being unprepared for exploration outside the neck.     

Antibody responses after splenectomy and splenic autoimplantation in rats

The sequential immunologic consequences of total splenectomy, partial splenectomy, and total splenectomy with splenic implantation were investigated in an animal model. Adult male albino rats were divided into six groups: sham operated, total splenectomy, 50% splenectomy, 75% splenectomy, splenectomy with 100% intraperitoneal splenic implantation, and splenectomy with 100% subcutaneous splenic implantation. At 2, 4, and 6 months following operation, animals in each group received a single intravenous injection of sheep red blood cells. Six days later, serum hemolysin titers were measured. Results suggest the following: normal immunologic function could be expected if approximately 50% of the spleen is left in situ; intraperitoneal or subcutaneous splenic implantation improves but does not normalize antibody responses; approximately 25% of splenic tissue left in situ results in better immunologic function than 100% ectopic splenic implantation; and following total splenectomy, antibody responses to intravenously administered antigen may improve with time.