Histocompatibility studies in a closely bred colony of dogs. II. Influence of the DL-A system of canine histocompatibility upon the survival of cardiac allografts.

The DL-A system of histocompatibility plays an important role in conditioning the survival of cardiac allografts in the unmodified canine host. The mean survival time of six cardiac allografts performed in DL-A-compatible littermate dogs obtained from a closely bred colony of beagles was 53.2 days, while the MST of transplants performed in seven DL-A-incompatible animals was 7.3 days. The MST of cardiac allografts performed in nine DL-A-compatible nonlittermate beagles was 26.3 days, as compared with 6.3 days in six DL-A-incompatible nonlittermate transplants. The results did not appear to be affected by Swisher erythrocyte-group incompatibilities. The MST of 28 cardiac allografts performed in randomly selected mongrel dogs was 10.0 days. Incompatibilities for DL-A antigens e, f, g, l, and m may constitute major barriers to transplantation, but antigens b, c, d, and k appeared to act as weak histocompatibility antigens. Under controlled conditions of donor-recipient DL-A compatibility, cardiac allografts may be less immunogenic than renal transplants. Heart transplants performed across major donor-recipient DL-A incompatibilities appeared, however, to be more vulnerable to the events of allograft rejection than renal allografts performed under similar conditions. The selection of optimally compatible donor-recipient combinations for organ transplantation may be aided materially by genetic studies of the transmission of DL-A antigens to the animals under consideration.

Validation of Practical Tools to Identify Walking Cadence to Reach Moderate Intensity.

It is recommended that adults get at minimum 150 minutes of moderate-to-vigorous physical activity in bouts of 10 minutes or greater every week. Walking cadence (steps per minute) is one easy way to estimate intensity required, however tools that claim to quantify walking intensity via walking cadence have not been validated in adults. We aimed to validate: 1- the accuracy of walking cadence measurement by the Piezo RxD pedometer, Polar Stride Sensor Bluetooth Smart foot pod, and Garmin Ant+ foot pod at different speeds and slopes and 2- the ability of the Piezo RxD to identify bouts of walking at moderate intensity using walking cadence. Inclusion criteria included being aged 19+ and the ability to reach moderate intensity when walking without incline as determined by a treadmill cardiorespiratory fitness test to determine 40% of VO2 reserve. Walking cadence measured from the three tools was compared to a manual count of walking cadence during a series of walking stages at several speeds (2.5-5.5 km/h) and inclines (0-15%). The ability of the Piezo RxD to quantify a 10-minute bout was determined by walking for 12 minutes at 40% of VO2 reserve measured by indirect calorimetry. All correlations between manual walking cadence counts and all devices were significant regardless of speed (r ranging from 0.469 to 0.999; p ≤ 0.05) and slope (r ranging from 0.887 to 0.996; p ≤ 0.05). The Piezo RxD was able to correctly measure a 10-minute bout of walking at moderate intensity for 50 of 51 participants. We found that all walking cadence devices provided accurate measurements of walking cadence. The Piezo RxD is an effective tool to quantify bouts of walking done at a minimum of moderate intensity.

Protruding aortic atheromas predict stroke in elderly patients undergoing cardiopulmonary bypass: experience with intraoperative transesophageal echocardiography.

Protruding atheromas of the aortic arch identified by transesophageal echocardiography have been implicated as a cause of stroke in elderly patients. One hundred thirty patients greater than or equal to 65 years of age were studied with intraoperative transesophageal echocardiography to detect aortic arch protruding atheromas and determine if these patients were at higher risk for perioperative stroke. Protruding atheromas were identified in 23 (18%) of 130 patients. In 19 (83%) of these 23 patients, palpation of the aortic arch at operation did not identify significant abnormalities. Five patients (4%) had perioperative stroke. Logistic regression identified aortic arch atheroma as the only historical or procedural variable that was predictive of stroke (odds ratio 5.8, 95% confidence interval 1.2 to 27.9, p less than 0.03). A history of peripheral or cerebrovascular disease, presence of aortic calcification, cardiac risk factors, age and duration of cardiopulmonary bypass did not predict stroke. In contrast, patients with protruding atheromas with mobile components were at highest risk. There were 3 (25%) of 12 patients with a mobile atheroma who had a stroke versus 2 (2%) of 118 patients without a mobile atheroma (chi-square = 10.3, p = 0.001). Displacement and detachment of the frail, protruding atherosclerotic material by aortic arch cannulation or by the high pressure jet emanating from the cannula tip may play an important role in the creation of embolization and stroke.

Definition of the safe lower limits of aortic resection during surgical procedures on the thoracoabdominal aorta: use of somatosensory evoked potentials.

The technique of intraoperative monitoring of somatosensory evoked potentials was applied to a canine model of spinal cord ischemia in an attempt to determine the safe lower limits of aortic resection during thoracic aortic surgery. Fifteen animals underwent left thoracotomy with institution of partial left atrial/femoral artery bypass for maintenance of distal aortic perfusion after proximal descending thoracic aortic exclusion. In Group I animals (n = 6, control), no further interventions were performed so that the effect of exclusion of vessels noncritical to spinal cord blood supply could be assessed by measurements of spinal cord blood flow and somatosensory evoked potentials. In Group II animals (n = 8), the level of distal aortic exclusion was progressively lowered until loss of somatosensory evoked potential (critical vessel exclusion) occurred. The effect of critical vessel exclusion on spinal cord blood flow was then assessed. Exclusion of multiple vessels noncritical to spinal cord blood supply (Group I) had no effect on spinal cord blood flow or function (somatosensory evoked potentials). Exclusion of vessels critical to spinal cord blood supply resulted in significant spinal cord ischemia (83.4% flow reduction, probability [p] less than 0.05 versus baseline) and ischemic spinal cord dysfunction (loss of somatosensory evoked potential).(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple valve operation for advanced valvular heart disease: results and risk factors in 513 patients.

To assess the results and incremental risk factors affecting outcome after multiple-valve operation in the early blood cardioplegia era of cardiac surgery, follow-up data (mean +/- SD 3.1 +/- 2 years) were obtained on 97% of 513 patients (mean age +/- SD 58.8 +/- 10.5 years) who underwent a multiple-valve procedure between June 1976 and August 1985. Preoperatively 41% of patients were in New York Heart Association functional class III and 54% in class IV. Three groups accounted for 98.6% of the patients: 57.7% had an aortic and mitral valve procedure, 29% had a mitral and tricuspid valve procedure and 11.9% had a triple-valve procedure. The overall hospital mortality rate was 12.5% and overall 5-year survival rate was 67.1%. Hazard function analysis for all deaths revealed systolic pulmonary artery pressure (p less than 0.0001), age (p = 0.005), triple valve procedure (p less than 0.005), concomitant coronary bypass operation (p less than 0.005) and prior cardiac surgery (p less than 0.002) as the significant incremental risk factors predicting decreased survival in the early hazard phase; diabetes (p less than 0.005) predicted decreased survival in the late hazard phase. Postoperatively the condition of 80% of the patients improved to functional class I or II; only 0.6% remained in functional class IV. The 5-year rate of freedom from late combined valve-related morbidity was 81.7% and that of freedom from late combined valve-related morbidity and mortality was 71.7%. These results demonstrate excellent clinical improvement and late survival after multiple valve operation in patients with advanced valvular heart disease, justifying aggressive surgical therapy in these patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Anterior leaflet procedures during mitral valve repair do not adversely influence long-term outcome.

OBJECTIVES: This study was done to assess the impact of anterior mitral leaflet reconstructive procedures on initial and long-term results of mitral valve repair. BACKGROUND: It has been suggested that involvement of the anterior leaflet in mitral valve disease adversely affects the long-term outcome of mitral valve repair. Our policy has been to aggressively repair such anterior leaflets with procedures that include triangular resections in some cases. METHODS: From June 1979 through June 1993, 558 consecutive Carpentier-type mitral valve repairs were performed. The anterior mitral leaflet and chordae tendineae were repaired in 156 patients (mean age 58 years). The procedures included anterior chordal shortening in 78 patients (50%), anterior leaflet resections in 44 (28%), resuspension of the anterior leaflet to secondary chordae in 42 (27%) and anterior chordal transposition in 27 (17%). Concomitant cardiac surgical procedures were performed in 75 patients (48%). RESULTS: The operative mortality rate was 2.5% (2 of 81) for isolated mitral valve anterior leaflet repair and 3.8% (6 of 156) for all mitral valve anterior leaflet repair. Freedom from reoperation at 5 and 10 years was, respectively, 89.7% (n = 160) and 83.4% (n = 24) for the entire series of 558 patients, 91.9% (n = 51) and 81.2% (n = 10) for patients with anterior leaflet procedures, 88.8% (n = 109) and 84.4% (n = 14) for patients without anterior leaflet procedures and 91.7% (n = 118) and 88.9% (n = 18) for patients without rheumatic disease. Logistic regression showed that rheumatic origin of disease (odds ratio 2.99), but not anterior leaflet repair, increased the risk for reoperation. CONCLUSIONS: These results demonstrate that expansion of mitral valve techniques to include anterior leaflet disease yields immediate and long-term results equal to those seen in patients with posterior leaflet disease.

Mechanism of relief of angina after coronary bypass surgery: an angiographic study.

Coronary angiography was performed before and after coronary revascularization in 67 patients. The interval between studies ranged from 1 to 38 months (average 9.9). The patients were separated into four clinical groups on the basis of their symptoms at the time of restudy; Group I, 13 asymptomatic patients; Group II, 19 patients with nonanginal chest pain (18 cases) or dyspnea (1 case); Group III, 12 patients whose angina was relieved but not eliminated; and Group IV, 23 patients whose angina was not alleviated. The graft patency rate was 72 percent in Group I, 78 percent in Group II, 61 percent in Group IIII and 34 percent in Group IV. The sum of diseased, but not bypassed and unsuccessfully bypassed arteries per patient was 1.6 in Groups I and II. 2.9 in Group III and 4.0 in Group IV. The incidence of perioperative myocardial infarction, defined using enzymatic and electrocardiographic criteria, was 8 percent for Group I, 26 percent for Group II, 25 percent for Group III and 52 percent for Group IV. Anginal relief after coronary bypass surgery is achieved by successful and complete revascularization rather than by perioperative myocardial infarction.

Masked abnormal drainage of the inferior vena cava into the left atrium.

A 6 year old boy with a large atrial septal defect, partial anomalous pulmonary venous drainage and unrecognized anomalous insertion of the inferior vena cava into the left atrium had cyanosis after closure of the atrial defect. Repeat study revealed direct drainage of the inferior vena cava into the left atrium with moderate arterial oxygen desaturation. At repeat operation an unusual positioning of the inferior vena cava was seen. After reopening of the atrial defect, the pulmonary venous and systemic venous drainage anomalies were identified. A Dacron patch was inserted so as to divert flow to the proper atrium. Repeat catheterization 3 months after operation revealed a normal heart with no obstruction; arterial oxygen saturation was normal. The child has continued to do well 3 years after operation.

Aortic valve replacement for aortic stenosis in persons aged 80 years and over.

Seventy-one patients aged greater than or equal to 80 years (mean +/- standard deviation 82 +/- 2) with aortic stenosis or mixed stenosis and regurgitation underwent aortic valve replacement alone (n = 35, group 1) or in combination with a coronary artery bypass procedure without any other valve procedure (n = 36, group 2). Preoperatively, 91% had severe cardiac limitations (New York Heart Association class III or IV). Hospital mortality was 12.7% overall (9 of 71), 5.7% (2 of 35) for group 1 and 19.4% (7 of 36) for group 2. Perioperatively, 1 patient (1.4%) had a stroke. Survival from late cardiac death at 1 and 3 years was 98.2 and 95.5%, respectively, for all patients, 100% for patients who underwent isolated aortic valve replacement, and 96.3 and 91.2%, respectively, for patients who underwent aortic valve replacement plus coronary artery bypass. Eighty-three percent of surviving patients had marked symptomatic improvement. Freedom from all valve-related complications (thromboembolism, anticoagulant, endocarditis, reoperation or prosthetic failure) was 93.3 and 80.4% at 1 and 3 years, respectively. Thus, short- and long-term morbidity and mortality after aortic valve replacement for aortic stenosis in patients aged greater than or equal to 80 years are encouragingly low, although the addition of coronary artery bypass grafting increases short- and long-term mortality.

Guidelines for safely opening a previous sternotomy incision.

Operations through a previous sternotomy incision are associated with significant hazards, including cardiac injury, excessive hemorrhage during and after cardiopulmonary bypass, and postoperative sternal instability. A technique for safely opening previous sternotomy incisions has been developed at New York University Medical Center which has proved satisfactory in over 150 patients. It has been demonstrated repeatedly to be free of the serious and often lethal intraoperative and postoperative complications previously associated with this procedure.

Fulminating noncardiogenic pulmonary edema. A newly recognized hazard during cardiac operations.

At New York University Medical Center over the past 18 months, a distinctive and potentially lethal syndrome of fulminating noncardiogenic pulmonary edema has been observed in three patients following cardiopulmonary bypass. The clinical appearance is virtually identical to that produced by acute left ventricular failure, and the condition could have been diagnosed incorrectly in the past as myocardial infarction with left ventricular failure and pulmonary edema. Thus it is uncertain whether this is a new syndrome or whether it has long been present. Fulminating noncardiogenic pulmonary edema can be diagnosed by finding a low left atrial or pulmonary artery wedge pressure combined with a high protein content in the pulmonary edema fluid when compared to simultaneous measurements of the plasma protein level. As no other etiologic agent could be identified in our three patients, the probable cause seems to be an unknown type of allergic reaction to blood or blood products, manifested by acute pulmonary edema--the pulmonary capillary membranes being the first to be exposed to fluids administered intravenously. The significant point is that a nearly fatal degree of pulmonary congestion can be managed safely and effectively with corticosteroids, antihistamines, positive-pressure ventilation, diuretics, and albumin. Presently, two important questions remain: (1) Should fluids be restricted and balloon pump counterpulsation and vasopressors utilized to maintain systemic pressure? (2) How long after administration of steroids is it safe to give intravenous albumin? Meanwhile, both the mechanism and frequency of this syndrome remain unknown.

The significance of coronary arterial stenosis during cardiopulmonary bypass.

Myocardial infarction may develop during an uneventful open-heart operation. In order to better understand this complication, we undertook an experimental study. The left circumflex coronary artery of 20 dogs was narrowed to 50 per cent of its area by a metal screw clamp to produce a localized coronary stenosis. Regional myocardial perfusion in the distribution of both the stenotic circumflex and normal left anterior descending (LAD) coronary arteries was measured by injection of a radioactive-labeled microsphere (15 +/- 5 mu). Circumflex coronary artery flow was measured with an electromagnetic flow probe. An epicardial electrogram was recorded in the distribution of the left circumflex. Measurements of regional myocardial perfusion, circumflex flow, and the epicardial electrogram were performed in each animal during the control (prebypass) state and during cardiopulmonary bypass with a beating and fibrillating ventricle. Half the animals had cardiopulmonary bypass performed at 50 mm. Hg perfusion pressure and half at 100 mm. Hg. The animals were put to death at the end of the study, and the hearts were sectioned, weighed, and counted. A cast was made of the stenotic circumflex coronary artery, the degree of stenosis is measured, and the per cent area stenosis calculated. The study showed that the effect of a 50 per cent coronary stenosis in reducing distal flow is apparent only during cardiopulmonary bypass at reduced pressure. The mechanism whereby a myocardial infarction develops during cardiopulmonary bypass could evolve from the development of a "critical" stenosis out of a mild-moderate one at a reduced perfusion pressure during cardiopulmonary bypass.

Unilateral sudden loss of hearing: an unusual complication of cardiac operation.

Between 1969 and 1978 7,000 patients underwent cardiopulmonary bypass at Bellevue and University Hospitals. In seven of these patients, sudden loss of hearing in one ear developed immediately after the operation. Four of the seven patients showed improvement in hearing after the initial loss, although in no case did the hearing return completely to normal. None of the patients had vertigo but two were listless postoperatively. Two of the operations were for congenital heart disease; the remainder were coronary artery bypass procedures. All of the affected patients were male. There was no predilection as to which ear was affected. The most likely cause is particulate emboli generated by cardiopulmonary bypass. Other possible sources of emboli include air, antifoam, fat, and particulate matter from calcified valves and the aorta. Improvement in the kind of pump and the addition of various filters in the period between 1969 and 1978 did not eliminate unilateral hearing loss. The relationship between cerebral emboli and decreased consciousness after operations is also discussed.

Surgical treatment for aneurysm of aberrant subclavian artery based on a case report and a review of the literature.

Experiences with the recent successful treatment of a patient with an aneurysm arising from an aberrant subclavian artery are described. The reported experiences with surgical treatment by others were reviewed in detail: Only 16 such patients were found, with a surprising frequency of serious complications. These data led to the conclusion that a two-stage approach, through right cervical and left thoracotomy incisions, seems to offer the ideal method of treatment for this unusual problem.

Intrathoracic extramedullary hematopoiesis simulating anterior mediastinal tumor.

Intrathoracic extramedullary hematopoiesis is a rare tumor occurring predominantly in the posterior mediastinum, most commonly in patients with congenital hemolytic anemias. The first reported case of this entity's occurring in the anterior mediastinum is described in a 68-year-old man with an incompletely characterized anemia. Definitive diagnosis was established only after median sternotomy and removal of the tumor.

Monitoring of somatosensory evoked potentials during surgical procedures on the thoracoabdominal aorta. IV. Clinical observations and results.

Thirty-three patients undergoing operations on the descending thoracic or thoracoabdominal aorta were monitored to evaluate causes and effects of spinal cord ischemia as manifested by changes in somatosensory evoked potentials. Maintenance of distal aortic perfusion pressure (greater than 60 mm Hg) by either shunt or bypass techniques in 17 patients resulted in preservation of somatosensory evoked potentials and a normal postoperative neurologic status, irrespective of the interval of thoracic cross-clamping (range 23 to 105 minutes). In 16 other patients in whom cross-clamp time ranged from 16 to 124 minutes, evoked potential loss was observed because of failure to provide distal perfusion (n = 8), inadequate maintenance of distal perfusion pressure (less than 60 mm Hg) despite shunt/bypass (n = 6), or interruption of critical intercostal arteries (n = 2). Incidence of paraplegia in the entire group was 15.1% (5/33) and was limited to only those patients in whom evoked potential loss occurred (5/16, 31.2%) (p = 0.02). Loss of somatosensory evoked potentials for more than 30 minutes resulted in a 71.2% (5/7) incidence of paraplegia, whereas no neurologic deficit was noted in patients (0/26) in whom evoked potential loss was either prevented or limited in duration to 30 minutes (p less than 0.001 versus loss for more than 30 minutes). Intraoperative monitoring of somatosensory evoked potentials is a sensitive indicator of spinal cord ischemia. Simple aortic cross-clamping, failure to maintain distal perfusion pressure above 60 mm Hg, and inability to reimplant critical intercostals in a timely fashion result in a high rate of paraplegia if duration of spinal cord ischemia as measured by somatosensory evoked potentials exceeds 30 minutes. Routine evoked potential monitoring during thoracoabdominal procedures appears useful in assessing the adequacy of spinal cord perfusion. Furthermore, it can alert the surgeon to the necessity for critical intercostal artery reimplantation as well as the need for adjustment or regulation of distal aortic perfusion.

Open-heart surgical centers. Standards and monitoring.

This article contains the essence of a report presented to the Council of The American Association for Thoracic Surgery (AATS) by an Ad Hoc Committee on Issues composed of the authors, on October 13, 1976. Because of urgent demand to have this information immediately available, early publication was desirable. However, to have official endorsement of the AATS would have necessitated waiting until April, 1977, the date of the next meeting of the Association. Since this would delay publication of this information for more than one year, it was considered reasonable by the Council that it be published as a free-standing statement of the authors.

Myocardial protection during prolonged aortic cross-clamping. Comparison of blood and crystalloid cardioplegia.

We compared the ability of blood and crystalloid cardioplegia to protect the myocardium during prolonged arrest. Twelve dogs underwent 180 minutes of continuous arrest. Group I (six dogs) received 750 ml of blood cardioplegic solution (potassium chloride 30 mEq/L) initially and every 30 minutes. Group II (six dogs) received an identical amount of crystalloid cardioplegic solution (potassium chloride 30 mEq, methylprednisolone 1 gm, and 50% dextrose in water 16 ml/L of electrolyte solution). Temperature was 10 degrees C and pH 8.0 in both groups. Studies of myocardial biochemistry, physiology, and ultrastructure were completed before arrest and 30 minutes after normothermic reperfusion. Biopsy specimens for determination of adenosine triphosphate were obtained before, during, and after the arrest interval. Regional myocardial blood flow, total coronary blood flow, and myocardial oxygen consumption were statistically unchanged in Group I (p greater than 0.05). Total coronary blood flow rose 196% +/- 49% in Group II (p less than 0.005), and left ventricular endocardial/epicardial flow ratio fell significantly in this group from 1.51 +/- 0.18 to 0.8 +/- 0.09, p less than 0.01 (mean +/- standard error of the mean. The rise in myocardial oxygen consumption was not significant in this group (34% +/- 36%, p greater than 0.05). Ventricular function and compliance were statistically unchanged in both groups. In Group II, adenosine triphosphate fell 18% +/- 3.4% (p less than 0.005) after 30 minutes of reperfusion; it was unchanged in Group I. Ultrastructural appearance in both groups correlated with these changes. We conclude that blood cardioplegia offers several distinct advantages over crystalloid cardioplegia during prolonged arrest.

Angina following myocardial revascularization. Does time of recurrence predict etiology and influence results of operation?

To assess the operative mortality and long-term results in patients undergoing repeat revascularization for recurrent angina, we analyzed 48 consecutive patients operated upon at New York University Medical Center between 1970 and 1978. Between January, 1970, and July, 1973, 15 patients underwent repeat revascularization with five operative deaths (33 percent). Thirty-three patients underwent similar operations from July, 1973, to July, 1978, with only one operative death (3 percent). Technical factors and improved methods of myocardial protection during the operation directly influence this decrease in operative mortality rate. The indication for reoperation was incapacitating angina developing within 2 months of the inital operation in 18 patients (early failures) and after more than 2 months in 30 patients (late failures). The early failures were most commonly attributed to technical factors (33 percent) and graft occlusion by exuberant pericardial scarring (33 percent). The late failures were commonly related to the development of new native coronary lesions (47 percent) and selection of an incorrect site for distal anastomoses (23 percent). The prognostic and therapeutic implications of these findings will be discussed in detail. Angina was abolished or significantly decreased in 90 percent of the survivors, and there were only two late deaths occuring 18 and 20 months postoperatively. These data indicate that patients undergoing repeat myocardial revascularization can be operated upon with low operative mortality rates and symptomatic improvement comparable to that of patients undergoing coronary artery bypass for the first time.

Experiences with the Carpentier techniques of mitral valve reconstruction in 103 patients (1980-1985).

A total of 103 patients, age range 2 to 77 years, had some type of Carpentier reconstruction for mitral insufficiency. The mitral insufficiency resulted from ruptured chordae in 52, prolapse in 13, rheumatic fever in 16, coronary disease in eight, congenital disease in nine, and endocarditis in five. Multiple abnormalities were usually present. Four patients had severe calcification of the anulus. A reconstruction was accomplished in almost all patients. A ring annuloplasty was performed in all but two small children, but annuloplasty alone was adequate in only 17 patients. Fifty-eight had resection of 1 to 4 cm of diseased mitral leaflet. In 23 patients, chordal transposition or shortening was employed. Aortic leaflet repair was done in 28. Shortened, fused chordae (one to eight) were divided in 13 patients. Additional procedures performed in 28 patients included coronary bypass in 14. A successful repair was accomplished in all but one patient (moderate residual insufficiency). Two late hospital deaths were unrelated to the mitral repair. Following hospital discharge, ring dehiscence necessitated repeat operation in one patient. Thromboembolism produced a permanent minor neurological deficit in only one patient. There have been no late recurrences of insufficiency. Recurrent endocarditis necessitated valve replacement in three patients. A late Doppler evaluation of 95 patients for mitral insufficiency revealed none in 82, a trace in 12, and moderate insufficiency in one. Late catheterization in 16 patients revealed no insufficiency. The data suggest that reconstruction, rather than prosthetic valve replacement, can be successfully performed in over 90% of patients with nonrheumatic, noncalcified mitral valves. A much wider use of the technique seems strongly indicated.