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Operative therapy is generally advocated for the management of chronic traumatic pseudoaneurysms of the aorta. A potential complication of both thoracic and abdominal aortic aneurysmectomies is paraplegia secondary to infarction or ischemia of the spinal cord. The present report describes a patient with a traumatic aneurysm of the lower thoracic aorta immediately adjacent to the origin of the anterior spinal artery, both delineated angiographically. In this particular situation, it was elected to follow the patient because the aneurysm was asymptomatic, small, and chronic, and because the risk of spinal cord injury associated with aneurysmectomy was estimated to be high. Serial computerized tomography (CT) scanning was used as a means of measuring the exact aneurysm size. Operation will be recommended if the aneurysm produces symptoms or enlarges, as demonstrated by CT scans.

One hundred consecutive patients who underwent resection of aneurysms of the left ventricle were reviewed. Eighty-four of these patients had resection or plication of an aneurysm of the anterior left ventricular wall either alone or in combination with coronary artery bypass grafting. In 27 patients who had little or no congestive heart failure, the primary indication for operation was disabling angina pectoris. In them the early mortality was 4% and late mortality, 4%. In nine other patients the primary indication for operation was life-threatening ventricular arrhythmias. In this group the early mortality was 56% and late mortality, 0%. Severe congestive heart failure was the primary indication for aneurysmectomy in 48 patients. In these patients the early mortality was 21% and late mortality, 34%. When the primary indication for operation was severe congestive heart failure, overall survival and postoperative results were best in patients in whom the nonaneurysmal left ventricle had good function preoperatively and was supplied by coronary arteries either unobstructed or favorable for bypass grafting; results were poorest in those patients with three-vessel coronary artery disease who had impaired motion of the lateral left ventricular wall and distal lateral wall vessels that were unfavorable for bypass grafting. It is concluded that patients with left ventricular aneurysms form a heterogeneous group in which the prognosis varies markedly. The probability of a good postoperative result can be predicted by careful preoperative analysis of a patient's symptoms, ventricular function, and coronary artery anatomy.

Thirty-three patients who had aortic valve replacement (AVR) for isolated aortic stenosis (AS) were retrospectively evaluated to determine the influence of preoperative ventricular function on the results of operation. Patients were arbitrarily divided by ejection fraction (EF) into Group I having EF 0.46 or above and Group II having EF 0.45 or below. Group II had significantly lower mean EF and cardiac index and higher left ventricular end-diastolic volume index and end-diastolic pressure. There were two early and no late deaths in 21 Group I patients. There were no early and five late deaths in 12 Group II patients. All Group I survivors and six of 12 Group II patients were New York Heart Association (NYHA) functional Class I or II at follow-up evaluation. No preoperative hemodynamic index was predictive of which Group II patients would do well. Mortality was substantially higher in patients with severe preoperative disability. Early or late death occurred in five of 12 patients who were NYHA functional Class IV before operation but in only two of 21 patients who were functional Class II or III preoperatively. We conclude that patients with isolated AS and poor left ventricular function have a low hospital mortality but an increased risk of late death or poor functional result following AVR. Excellent functional results can be obtained after AVR in most patients with AS and good left ventricular function and approximately half of the patients with AS and poor left ventricular function.

From 1966 to 1976 a flexible, heparin-coated shunt was used for operative procedures on the thoracic aorta and great vessels in 25 patients aged 15 to 78 years. Twenty patients had resection of aneurysms of the descending thoracic aorta. There was 1 death in 15 patients undergoing elective resection and 2 deaths (both from rupturing aneurysms) in 5 patients having emergency resection. The shunt was used in 5 patients who had procedures involving involving the great vessels. There have been no complications attributable to the shunt in either group. The advantages of this shunt include elimination of the need for systemic heparin, avoidance of hypertension during cross-clamping, and adequate perfusion of the distal cirulation without an interposed pump. Because of the ease of handling, low risk, and versatility, we consider the use of this shunt the preferred method for support in elective procedures of the thoracic aorta and great vessels.

The clinical and laboratory findings of 28 patients identified as having late pericardial effusions were examined. Eleven of these patients were asymptomatic; 9 patients had moderate symptoms including fatigue, malaise, weight gain, and dyspnea on exertion, and 8 patients with similar symptoms had evidence of cardiac tamponade. Ten patients underwent right heart catheterization in the intensive care unit; normal hemodynamics were confirmed in 4 and cardiac tamponade in 6 patients. Pericardiocentesis was effective in decompressing cardiac tamponade in 7 of 8 patients. One patient required operative subxiphoid drainage after unsuccessful pericardiocentesis. In addition, 5 patients with moderate clinical symptoms and pericardial effusions, who did not have cardiac tamponade, underwent pericardiocentesis because of a need for chronic anticoagulant therapy. The remaining patients were managed successfully by observation, discontinuation of warfarin when possible, fluid restriction, and diuretic therapy. All but 1 patient was symptomatically improved. A diagnostic and therapeutic schema is presented as an aid to early recognition of this troublesome and potentially lethal complication.

Ninety-five bypass graft anastomoses in 52 patients dying up to 4 years after direct coronary revascularization were studied at autopsy by angiograms and serial histologic sectioning of the graft-artery anastomosis. When new coronary occlusions and narrowings occurred, they were adjacent to either the proximal or distal ends of the anastomosis and were due to compression or loss of circumference of the arterial lumen (40 per cent), thrombus formation (40 per cent), mural dissection of the coronary wall (8 per cent) or the combination of compression and thrombosis (12 per cent). Small coronary artery diameter, local atheromas, and extension of the arteriotomy into a branch vessel were significant factors predisposing to occlusive changes. The findings emphasize the importance of careful artery selection for bypass, the need to avoid local vascular disease and branch-points, and the technical difficulties encountered in the presence of local vascular lesions or small coronary arteries.

A case of fatal pulmonary hemorrhage secondary to catheterization with a balloon-tipped catheter is described, and the literature describing possible mechanisms for this complication is reviewed. A common denominator in patients suffering pulmonary hemorrhage is pulmonary hypertension. Recommendations for management of this complication are discussed.

Cardiac tamponade occurring late after open-heart surgery is a frequently fatal complication. Of the 13 cases previously reported in the literature, there were seven deaths. In this report, three additional patients with late cardiac tamponade successfully treated are presented. Postoperative anticoagulation with Coumadin appeared to contribute to this complication. Increased awareness of late cardiac tamponade allowing prompt recognition and immediate decompression of the pericardial sac should lower the high mortality rate previously associated with the condition.

Right ventricular loading leads to diastolic septal flattening in man without necessarily requiring right ventricular pressure to exceed left ventricular pressure. This observation suggested that the unstressed septal configuration is flat and that its normal concave shape is due to the left-to-right transseptal pressure gradient. To examine this hypothesis, we studied septal configuration by two-dimensional echocardiography in nine patients with normal global and regional left ventricular function during surgery for coronary artery disease. The transseptal pressure gradient was obtained from pulmonary capillary wedge pressure minus right atrial pressure. Measurements were obtained at control (open chest, intact pericardium [C]), with the pericardium open (OP), on cardiopulmonary bypass (CPB), and after cardiac arrest (CA). There were no changes in any measurements between C and OP or between CPB and CA. Left ventricular end-diastolic cavity area decreased from 16.5 +/- 2.1 cm2 at C to 11.1 +/- 4.5 cm2 after CPB, and further decreased to 8.9 +/- 3.5 cm2 after CA (p less than .001), yet the septum flattened, as shown by an increase in its radius of curvature from 1.7 +/- 0.5 cm during C to 2.5 +/- 0.7 cm after CPB, and to 2.9 +/- 1.0 cm after CA (p less than .001), or from 0.4 +/- 0.1 to 0.8 +/- 0.4 to 1.1 +/- 0.5 U (p less than .001) when normalized for cavity area. Diastolic transseptal pressure gradient was reduced from 4.1 +/- 2.3 mm Hg during C to 1.1 +/- 1.8 mm Hg after CPB, and to 0.5 +/- 1.4 mm Hg after CA (p less than .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Between November, 1973, and March, 1980, 43 patients underwent isolated aortic valve replacement with 19 mm Björk-Shiley prostheses at the Johns Hopkins Hospital. There were 4 male and 39 female patients ranging from 12 to 75 years old (mean, 54.5 years). Average weight was 62 +/- 2 kg and average body surface area, 1.64 +/- 0.3 m2. Five patients died within thirty days of operation; however, since 1975, hospital mortality has been 5.9%. The 38 survivors have been followed up for as long as 85 months (mean, 40 months). There were 4 late deaths, and actuarial survival in patients discharged from the hospital was 81% at five years. All long-term survivors were in New York Heart Association Functional Class I (29 patients) or Class II (5 patients). Preoperative and postoperative echocardiograms in 17 patients demonstrated significant decreases in mean left ventricular wall thickness (12.9 +/- 1.8 mm vs 10.3 +/- 1.4 mm; p less than 0.001) and in left ventricular mass (262 +/- 95 gm vs 188 +/- 50 gm; p less than 0.02). Postoperative cardiac catheterization data were obtained from an additional 24 patients undergoing aortic valve replacement with the 19 mm Björk-Shiley prosthesis at the National Heart Institute. Average peak systolic gradient at rest was 16 mm Hg (range, 0 to 45 mm Hg) and was found to be directly related to body surface area (r = 0.60, p less than 0.002). Average effective valve orifice area was 1.06 cm2 (range, 0.63 to 2.02 cm2). For patients with small aortic roots, aortic valve replacement with the 19 mm Björk-Shiley valve is a satisfactory and, perhaps, preferable alternative to aortic annuloplasty to accommodate larger sized prostheses.

Our experience with the management of two patients with life-threatening aortic disease during pregnancy is presented with a review of the literature. One of our patients had intimal disruption caused by trauma; the other had probable Ehlers-Danlos type IV syndrome, causing an acute dissection of the descending thoracic aorta and eventually requiring replacement of the aorta from the left subclavian artery to common iliac arteries. The challenge of treating both the pregnant woman and the fetus was managed successfully by an emergent cesarean section followed by Dacron graft replacement of the descending thoracic aorta. The literature reviewed disclosed that aneurysm expansion producing symptoms and dissection is most common during the third trimester and during labor and delivery in patients with or without Marfan's syndrome. Half of the aortic dissections in women less than 40 years of age occur in association with pregnancy. The available evidence indicates that patients with known valvular or aortic disease should have surgical repairs during the first or second trimester and thereafter have delivery by cesarean section. However, patients with acute aortic problems near term appear to be better managed by cesarean section followed promptly by treatment of the aortic disease.

This study was designed to evaluate the sensitivity of changes in myocardial carbon dioxide and oxygen tensions as indicators of regional myocardial ischemia and also to determine to what extent these changes can be related to changes in intramyocardial ST segment voltage. Changes in ST segment voltage recorded in unipolar epicardial electrodes proved to be a less-sensitive indicator of underlying myocardial ischemia than were changes in ST segment voltage recorded in unipolar intramyocardial electrodes. In 9 dogs, regional ischemia was produced by placing a variable constrictor on the left circumflex coronary artery; circumflex flow was monitored. Myocardial carbon dioxide and oxygen tensions were measured using a mass spectrometer. Unipolar electrograms were recorded using a multicontact plunge electrode. With progressive degrees of proximal stenosis, ranging from a critical stenosis, which is associated with a decrease in mean flow of less than 15%, to a severe stenosis associated with and 80% decrease, ST voltage increased 21 mv and carbon dioxide tension increased 84 mm Hg, but oxygen tension decreased only 7 mm Hg. The study suggests that increases in intramyocardial ST segment voltage, an index of myocardial ischemia, are associated with parallel increases in myocardial carbon dioxide tension, each providing a more sensitive quantitative correlate of regional myocardial ischemia than do decreases in oxygen tension. The local accumulation of carbon dioxide may be an important pathophysiological mechanism in myocardial ischemia.

Operative repair of ventricular aneurysms should improve left ventricular function. Despite its theoretic advantage, the mortality following this operation is high, and many patients have severe postoperative hypotension. The cardiac findings were studied in 18 patients who died after repair of ventricular aneurysms. All hearts were examined at autopsy after postmortem coronary arteriography and fixation in a distended state. Five patients in Group I had intractable fatal postoperative hypotension, 7 in Group II initially had severe hypotension that improved, and 6 in Group III did not have postoperative hypotension. Curvature thickness indexes (CTIs) of the ventricular segments, which correlate with their pressure-producing activity, were determined in the 18 hearts. CTIs for the left ventricular free wall and septum were lower in Group I and Group II patients with hypotension than those in Group III without. The reduced CTIs in patients with postoperative shock appear to arise as a result of ventricular reconstruction that reduces ventricular wall curvature. The authors suggest that left ventricular function after aneurysm resection would be improved by inverting, rather than everting, the edges of the ventriculotomy, thereby increasing wall curvature and the CTI. Noninvasive determinations of the CTI may prove of value in guiding topographic reconstruction of ventricles with aneurysms.

Postinfarction ventricular septal defect (VSD) carries a grave prognosis. Surgical closure appears to improve survival. Eighteen patients with postinfarction VSD are reviewed. Nine died before operation could be performed and 9 underwent closure of the VSD; 4 patients are late survivors. Factors which appear to influence survival are: (1) time of surgical intervention after appearance of VSD, (2) presence or absence of cardiogenic shock, (3) location of the infarct, and (4) operative approach to the VSD. Based on these factors, a method of management for postinfarction VSD is outlined.

An autotransfusion technique has been developed for collection and reinfusion of shed mediastinal blood. This system has been routinely applied in the postoperative management of 592 consecutive adult and 108 pediatric cardiac surgical patients. Two hundred seventy-one adult patients (46%) and thirty-six pediatric patients (33%) actually received autologous blood. Autotransfusion volume ranged from 50 to 21,350 ml per patient. In 1976 at our institution, homologous transfusion requirements averaged 8.4 +/- 0.7 units per adult patient. During 1978, with the routine use of postoperative autotransfusion, bank blood transfusions were lowered to 4.2 +/- 0.3 units per patient (p less than 0.001). In contrast to perioperative autotransfusion techniques, collection and reinfusion of shed mediastinal blood is particularly useful for intravascular volume replacement in patients with serious postoperative bleeding.

Changes in myocardial carbon dioxide (PmCO2) and oxygen tension (PmO2) measured by mass spectrometry have been shown to reflect quantitatively progressive degrees of regional myocardial ischemia associated with stepwise reduction in coronary blood flow. The present study utilized mass spectrometry to assess the severity of regional myocardial ischemia developing during atrial pacing in the presence of a flow-limiting proximal critical coronary artend subendocardial layers was measured by the radioactive microsphere technique. Application of a "critical stenosis" resulted in a 6-mmHg decrease in PmO2 and a 17-mmHg increase in PmCO2 in the region of the myocardium supplied by the stenosed vessel. The addition of atrial pacing resulted in a 3-mmHg further decrease in Pmo2 and a 40-mmHg further increase in PmCO2. In the region of myocardium supplied by the critically stenosed vessel MBF increased in the subepicardial layer, but decreased or remained unchanged in the subendocardial layer. The failure of myocardial blood flow to increase in deeper myocardial layers in response to the increased myocardial oxygen demand of atrial pacing would provide a mechanism for the development of subendocardial ischemia in the presence of a critical coronary stenosis.

A modification of the usual approach to the mitral valve is described and illustrated. This technique employs right atriotomy and interatrial septotomy, which can be easily performed when standard left atriotomy does not provide satisfactory mitral valve exposure. While this modification is not often necessary, it can be helpful in patients with a small left atrium, especially those with a small left atrium and associated left ventricular hypertrophy.

Left ventricular (LV) aneurysms were resected in 27 patients for treatment of congestive heart failure and in five patients for treatment of ventricular arrhythmia. There were eight early (25 per cent) and five late (15 per cent) deaths. Preoperative hemodynamics including analysis of left ventriculograms in the right anterior oblique position did not consistently predict survival. In contrast, coronary artery anatomy appeared to influence the mortality rate strikingly in patients with congestive heart failure. The hospital mortality rate was 6 per cent and the late mortality rate was 13 per cent for 16 patients with one-or two-vessel coronary artery disease, but with unobstructed LV lateral wall blood supply. All but one of the survivors obtained a good late result. In nine patients with two-and three-vessel coronary artery disease and obstructed LV lateral wall blood supply there were six hospital deaths and two late deaths. It is concluded that the presence or absence of occlusive disease in the arteries supplying the LV lateral wall is an important determinant of the mortality rate associated with resection of anterior apical LV aneurysms in patients with severe congestive heart failure.

The Starr-Edwards ball valve prosthesis is generally the standard by which other cardiac valve substitutes are compared. This report reviews information pertaining to several prostheses--the Beall mitral valve and the Bjork-Shiley, Braunwald-Cutter, Lillehei-Kaster and Smeloff-Cutter aortic and mitral valves--considered by some to have specific advantages over the Starr-Edwards valves. Hospital and late mortality rates after valve replacement are comparable for the four aortic valve prostheses reviewed and depend more on patient selection than on the specific prosthesis utilized. Extensive clinical experience with the Bjork-Shiley aortic valve indicates that this prosthesis offers hemodynamic advantages over ball valve prostheses, especially in patients with a small aortic root. Clinical experience with the Lillehei-Kaster pivoting disc prosthesis has been less extensive, but this model provides theoretical hemodynamic advantages similar to those of the Bjork-Shiley aortic valve prosthesis. Problems associated with cloth wear and the unexpectedly slow rate, in man, of tissue ingrowth into the fabric of the Braunwald-Cutter aortic valve prosthesis have been discouraging, although this prosthesis has been associated with a very low thromboembolic rate in patients receiving anticoagulant therapy. The Smeloff-Cutter aortic prosthesis is hemodynamically similar to the Starr-Edwards prosthesis and has been proved to be a reliable and durable aortic valve substitute over the past several years. Mortality after mitral valve replacement is also largely influenced by factors other than prosthetic valve design. On the basis of postoperative data, the five mitral valve prostheses reviewed do not appear to have substantial hemodynamic differences. For patients with a small left ventricular cavity the low profile prostheses, such as the Beall, Bjork-Shiley and Lillehei-Kaster, may be advantageous. Most available evidence indicates that patients receiving aortic or mitral valve prostheses should be given anticoagulant therapy postoperatively.

In a randomized prospective study of patients having cardiac surgery, autologous blood collected from mediastinal tubes was autotransfused preferentially in 63 patients (ATS), whereas 51 patients received bank blood for transfusion (control). Comparison of the two groups showed no significant difference in regard to age, sex, operations performed, or total postoperative bleeding (ATS 813 +/- 121 ml. per square meter versus control 711 +/- 93 ml. per square meter; N.S.) Although mean postoperative blood replacement was similar in the two groups (ATS 4.3 +/- 0.6 units per patient versus control 4.8 +/- 0.6 units per patient), requirements for transfusion of stored bank blood were reduced by 50 percent in the ATS group (ATS 2.4 +/- 0.3 units per patient versus control 4.8 +/- 0.6 units per patient; p less than 0.005). Coagulation studies demonstrated that this blood was defibrinogenated; yet it contains significantly more platelets and clotting factors than does bank blood. In this study, autotransfusion of shed mediastinal blood was safe and simple. It significantly reduced bank blood requirements and resulted in substantial financial savings for the patients and the hospital.

The first 153 cases of saphenous vein aortocoronary bypass surgery performed at The Johns Hopkins Hospital were reviewed. Eighty-eight percent of the 140 late survivors reported significant symptomatic improvement. Seventy-one unselected patients consented to complete reevaluation at a mean interval of 6.1 months postoperatively. Vein bypass patency in this group was 66 percent. Eighty-two percent of these 71 patients had improved performance on electrocardiographic stress testing. There were no significant differences between hemodynamic status on pre- and postoperative studies regardless of the status of vein bypass patency. Repeat coronary angiography revealed a 30 percent incidence of new total occlusions of the intrinsic coronary circulation. Segmental wall motion on ventriculography was improved in 12 percent, unchanged in 50 percent and decreased in 38 percent of the segments analyzed. Localized electrocardiographic changes compatible with myocardial damage developed in the immediate postoperative period in 45 of these patients (63 percent); in 38 of the 45, these changes corresponded to new angiographic abnormalities. Physiologic mechanisms underlying symptomatic improvement were sought by identification of an "angina-producing" myocardial segment. In most instances, alleviation of angina could be related to either: (1) a patent bypass graft into an unchanged intrinsic coronary artery with presumed increased blood flow to the distal coronary segment, or (2) occlusion of the bypass graft and the corresponding coronary artery with probable infarction of previously ischemic myocardium. Current criteria for the selection of patients undergoing coronary bypass surgery are reviewed in the light of these findings. It is concluded that relief of disabling angina is the major indication for surgery. Prevention of myocardial infarction and improvement in left ventricular function are at present less reliable objectives.

Experience was reviewed with 471 consecutive patients who had coronary artery bypass (CAB) operation alone. The hospital mortality rate was 2% in 341 patients operated on for treatment of stable angina pectoris. There were ten deaths (7.7%) in the 130 patients who underwent CAB for treatment of unstable angina. In this series, age greater than 70 years, poor left ventricular function, distal coronary arteries unfavorable for grafting and the presence of main left coronary artery disease were factors associated with increased operative mortality. In 78 patients with unstable angina who had none of these increased risk factors, the mortality rate was 1.3%. Hospital mortality was 33% in patients older than 70 years and 29% in patients with poor left ventricular function and/or distal vessels unfavorable for grafting. In 23 of the 130 patients, the only increased risk factor present was severe stenosis of the main left coronary artery and one of them (4.3%) died. Thus, when elderly patients and patients with poor left ventricular function or poor distal vessels were excluded, the hospital mortality rate associated with CAB in patients with unstable angina was low (2.0%, 2/101 patients) and equal to that for operation in patients with stable angina pectoris.

Mass spectrometry was utilized to determine myocardial gas tensions in dogs subjected to cardiopulmonary bypass. Myocardial ischemia occurred in animals with normal coronary arteries when cardiopulmonary bypass perfusion pressure fell 40 to 60 mm Hg below the mean aortic pressure measured prior to bypass. Myocardial ischemia did not occur, or could be eliminated when present, if cardiopulmonary bypass perfusion pressure was maintained near prebypass mean aortic pressure. In animals with constricted circumflex coronary arteries, the adverse effect of low perfusion pressure on myocardial metabolism during cardiopulmonary bypass was found to be more severe in areas of myocardium supplied by the stenotic coronary artery. It is concluded that maintenance of cardiopulmonary bypass perfusion pressure near the level of preoperative mean aortic pressure will help prevent myocardial ischemia during operation; particularly in patients with coronary artery disease.

Four patients are reported who underwent repair of partial anomalous pulmonary venous drainage with intact atrial septum. One patient also had azygos continuation of the inferior vena cava and two patients had associated mitral stenosis. Diagnostic considerations and guidelines for operative repair are presented.

A five year experience with 20 patients who had penetrating vascular injuries of the thoracic outlet was reviewed. A median sternotomy with extension into the right neck was used to explore six patients with right subclavian vascular injuries. With injuries to the origin of the left common carotid artery, repair was accomplished through a median sternotomy combined with a left anterior thoracotomy in one patient and through a left posterolateral thoracotomy in the other. Injury to the left subclavian vessels occurred in five patients and was exposed through a left anterolateral thoracotomy combined with a supraclavicular incision in four patients and through a supraclavicular incision with clavicular resection in one patient. Axillary vessel trauma generally was managed with an extrathoracic incision only. The two deaths in this series were due to postoperative respiratory complications (mortality rate of 10%). Twenty arteries were repaired and all were patent on follow-up examination. Associated neural and venous injury caused significant morbidity in 28% and 10% of patients, respectively. As a result of this experience we continue to recommend an extended median sternotomy for repair of right-sided cervicothoracic vascular injury. Anterior or posterolateral thoracotomy combined with a supraclavicular incision is advocated for trauma to left-sided vessels of the thoracic outlet. When possible, injured veins should be repaired rather than ligated.

Placement of permanent cardiac pacemakers in children presents technical problems that are not encountered in the adult. Problems unique to pacemaker implantation in children are related to the patient's size, the relative bulkiness of pulse generators, the lack of subcutaneous tissue, and the child's growth and long life expectancy. Based on our experience with implantation of 27 permanent cardiac pacemakers in 13 children, we have found that the use of small pulse generators, placement of epicardial leads, insertion of properitoneal pulse generators, and use of recharabeable pacemakers are satisfactory methods in children.

In a previous study from this laboratory, regional myocardial ischemia developed distal to a critical coronary stenosis in the fibrillating heart on cardiopulmonary bypass when myocardial perfusion was non-pulsatile. To assess the effect of pulsatile perfusion on the development of the fibrillation-induced ischemia, 10 dogs were placed on total cardiopulmonary bypass with the heart in the vented fibrillating state. A critical stenosis was applied to the left anterior descending artery (LAD). Pulsatile perfusion with a pulse pressure of 35 mm Hg and a pulse rate of 100/min was produced by a new method developed in this laboratory. During the 2 hours of bypass, ischemia in the LAD-supplied myocardium was assessed by changes in intramyocardial oxygen (PmO2) and carbon dioxide (PmCO2) tensions and by regional arterial-coronary venous lactate difference. With linear perfusion, regional ischemia in the LAD myocardium had been evidenced by a low PmO2 (8 +/- 3 mm Hg), a high PmCO2 (170 +/- 25 mm Hg) and regional lactate production (9.2 +/- 4.2 mg/100 ml). In contrast with pulsatile perfusion intramyocardial gas tensions remained stable during the 2 hours on bypass (PmO2 = 21 +/- 3 mm Hg, PmCO2 = 65 +/- 5 mm Hg, P less than 0.05 vs linear flow study) and lactate consumption was demonstrated (+17.7 +/- 2.9 mg/100 ml, P less than 0.001 vs linear flow group). With linear perfusion, myocardial blood flow to the LAD area had decreased 56 +/- 8% in the subendocardial layer and 46 +/- 7% in the subepicardial layer. In the dogs receiving pulsatile flow during bypass, regional LAD blood flow remained unchanged over the 2-hour bypass period and was significantly higher than the flow with linear flow (P less than 0.05). These data indicate that fibrillation-induced regional myocardial ischemia distal to a critical stenosis can be prevented by maintaining pulsatile perfusion during cardiopulmonary bypass.

Sixteen patients aged 22-64 years have undergone removal of atrial myxoma at the Johns Hopkins Hospital. The first two patients had myxomas removed by closed surgical approach, and both died. Fourteen consecutive patients have undergone operation with the aid of cardiopulmonary bypass, and all survived. There has been one late death unrelated to myxoma. Current surgical approach is excision of the tumor and its stalk or base and resection of the portion of intra-atrial septum to ensure complete removal. Recently a new diagnostic technique of two-dimensional phased array real time echocardiography has been used in four patients, including a pregnant woman, to confirm the clinical diagnosis of atrial myxoma. This technique provides a two-dimensional view of both atria and ventricles in cross section or sagittal view. This noninvasive method is painless, is independent of cardiac function and carries no risk or radiation hazard. The two-dimensional echocardiogram is superior to the standard one-dimensional or M-mode echocardiogram for diagnosis of myxoma in that it can evaluate simultaneously both right and left atria, can detect smaller space-occupying lesions because of better resolution and can more readily determine the size of the lesion and its stalk, can evaluate the mobility of the tumor and can determine more accurately the extent of tumor obstruction. Because of these qualities, we have relied on two-dimensional echocardiography as the definitive diagnostic procedure for detection of atrial myxoma. Currently operation for atrial myxoma is performed without cardiac catheterization or angiocardiography.

The methodology for use of the mass spectrometer for the measurement of intramyocardial gas tensions in the canine preparation is described. Baseling studies were carried out initially in 36 animals, and control levels for myocardial oxygen tension and myocardial carbon dioxide tension were 19 mm Hg (S.D. 6 mm Hg) and 43 mm Hg (S.D. 10 mm Hg), respectively. Myocardial oxygen tension was not altered significantly by varying the arterial oxygen tension between 65 and 300 mm Hg. However, myocardial carbon dioxide tension increased linearly with increased arterial carbon dioxide tension. In 15 dogs placed on total cardiopulmonary bypass, a perfusion pressure 40-60 mm lower than the control mean arterial pressure resulted in myocardial ischemia with a decrease in myocardial oxygen tension and an increase in myocardial carbon dioxide tension. A subsequent increase in perfusion pressure to control levels resulted in resolution of ischemia and return of myocardial oxygen and carbon dioxide tensions to their control level. In another series of open-chest dogs on cardiopulmonary bypass, a proximal constriction applied to the left coronary circumflex artery resulted in a marked decrease in myocardial oxygen tensions and a marked increase in myocardial carbon dioxide tensions in the region supplied by the constricted vessel. In yet another series of open-chest dogs, it was found that incremental decreases in coronary flow established by constriction of the circumflex artery resulted in an exponential increase in both myocardial carbon dioxide tensions and ST-segment elevation as determined by a 25-gauge multi-contact plunge electrode placed in the posterior left ventricular wall. It appears that mass spectrometry techniques for evaluating myocardial ischemia have several advantages over myocardial biopsy techniques for assay of ATP and lactate, and also over the technique of coronary sinus lactate determination.

Myocardial performance in the immediate postoperative period was studied 49 cardiac surgical patients treated with nitroprusside alone. With a thermodilution catheter positioned in the pulmonary artery, cardiac output was calculated and cardiac index, systemic vascular resistance index, and stroke work index were derived before after treatment with nitroprusside. The drug was a administered to all patients because of elevated systemic vascular resistance index. Based on their mean arterial pressure and cardiac index before treatment, the patients fell into two groups. Group I patients (N = 25) had elevated mean arterial pressure and normal cardiac index. Group II patients (N = 24) had normal mean arterial pressure and subnormal cardiac index. Nitroprusside administration resulted in a significant reduction of systemic vascular resistance index in all patients. In Group I the mean arterial pressure was lowered significantly while cardiac index increased only slightly. In Group II there was no change in arterial pressure, but cardiac index improved significantly. The results not only confirm that nitroprusside is effective in managing postoperative hypertension, but also demonstrate that in patients with postoperative left ventricular failure, the drug can improve cardiac output by reducing systemic vascular resistance without significantly lowering arterial blood pressure.