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Biomedical subjects

J S Rankin

Publications and source records attributed to J S Rankin.

At least 55 records · Page 3Linked to original sources
PubMed1990

Clinical evaluation of single versus multiple mammary artery bypass.

The superior patency and clinical advantages of internal mammary artery (IMA) grafting are well established. However, the relative benefits of routine multiple IMA grafting remain uncertain. To determine whether routine multiple compared with single IMA utilization improved survival of patients undergoing coronary bypass procedures, 1,063 patients were prospectively allocated, beginning in 1984, to divergent management strategies of single (group 1, n = 420) versus multiple IMA grafting (group 2, n = 643). Subsequent analysis of anatomical extent of disease and preoperative baseline risk factors showed no differences (p = NS) between the two groups. All variables reflecting operative technique were similar (p = NS) for the two groups, except 74% of group 1 patients with multivessel disease received a single IMA graft, whereas 71% of group 2 patients with multivessel disease received multiple IMAs (p less than 0.05). By multivariate analysis, impairment of left ventricular ejection fraction, acute evolving myocardial infarction, advanced age, and unstable angina were incremental risk factors for mortality (all p less than 0.03), but group assignment (p = 0.4) and ultimate therapy were not (p = 0.6). Survival probabilities (expressed as 30-day group 1/group 2; 4-year group 1/group 2) were overall (0.97/0.98; 0.93/0.90), elective (0.98/0.99; 0.97/0.92), acute (0.95/0.97; 0.89/0.88), age of less than 65 years (0.98/0.99; 0.97/0.93), age of 65 years or older (0.93/0.97; 0.84/0.89), ejection fraction of 0.40 or more (0.97/0.99; 0.95/0.94), ejection fraction of less than 0.40 (0.95/0.96; 0.87/0.82), nondiabetic (0.98/0.98; 0.94/0.91), and diabetic (0.92/0.97; 0.88/0.87). No differences in survival were significant (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Disease↗
PubMed1990

The effects of dopamine on myocardial functional recovery after reversible ischemic injury.

Dopamine frequently is used to improve cardiac performance after acute myocardial ischemia. Inotropic agents, however, increase myocardial oxygen demand and could potentially delay recovery from ischemic injury. To evaluate this problem, we studied eight chronically instrumented dogs in the conscious state and performed two 15-minute coronary occlusions 48 hours apart. After one of the occlusions, either dopamine (15 micrograms/kg/min) or saline placebo was administered intravenously from 1.0 to 1.5 hours of reperfusion. The alternative infusion was given during the second study. Preload recruitable work area, the area beneath the stroke work versus end-diastolic length relationship, was used to assess intrinsic myocardial performance. Ischemia decreased preload recruitable work area to 13% of control after both occlusions. After reperfusion, a 30-minute dopamine infusion acutely increased myocardial function nearly threefold as compared with placebo. Myocardial performance after dopamine administration, however, was significantly depressed compared with placebo throughout the remaining 24 hours of reperfusion (p less than 0.01). These data indicate that dopamine may impair functional recovery after ischemic myocardial injury and suggest that inotropic interventions should be used in this setting only when absolutely indicated.

Animals↗
PubMed1990

Effects of the left ventricular assist device on right ventricular function.

Right ventricular failure is a leading cause of death in patients who require the left ventricular assist device. Previous reports suggested right ventricular functional deterioration during left ventricular assist but lacked a method by which right ventricular function could be quantified adequately. This study examined the effects of left ventricular volume unloading on right ventricular systolic function by means of the stroke work/end-diastolic volume relationship, a load-insensitive index of myocardial performance. In 12 anesthetized open-chested dogs, right ventricular and left ventricular pressures were measured with micromanometers while ultrasonic dimension transducers measured left and right ventricular orthogonal diameters. Left ventricular unloading was accomplished with left atrial-to-femoral artery bypass with a centrifugal pump. Data were recorded during transient vena caval occlusion in the control state and with maximal left ventricular unloading by full support by the left ventricular assist device. Modified ellipsoidal geometry was used to calculate simultaneous biventricular volumes, and linear regression analysis of right ventricular stroke work versus end-diastolic volume was used to quantify right ventricular systolic function. Average slope and x intercept of this relationship under control conditions were 2.2 +/- 0.3 X 10(4) erg/ml and 10.7 +/- 5.0 ml, respectively. During full support by the left ventricular assist device (mean flow rate, 2.4 +/- 0.3 L/min), left ventricular end-diastolic volume decreased by 31% (p less than 0.01), left ventricular septal-free wall diameter decreased by 7% (p less than 0.001), and rate of rise of right ventricular peak positive pressure declined by 13% (p less than 0.05). The corresponding slope and x intercept of the right ventricular stroke work/end-diastolic volume relationship during full unloading of left ventricular assist device were 2.3 +/- 0.3 X 0.3 X 10(4) erg/ml and 14.3 +/- 4.8 ml, respectively; these values were not significantly different from control values (p greater than 0.5). Additionally, analysis of right ventricular end-diastolic pressure-volume relationships suggested improved right ventricular chamber compliance, although the effects were small and did not reach statistical significance (p = 0.10). These data imply that marked alterations in biventricular geometry accompanying left ventricular volume unloading by the left ventricular assist device in a normal heart do not significantly alter right ventricular performance characteristics.

Animals↗
PubMed1989

The evolution of medical and surgical therapy for coronary artery disease. A 15-year perspective.

To elucidate the factors associated with improved survival following coronary artery bypass surgery, we studied 5809 patients receiving medical or surgical therapy for coronary artery disease. Three factors were associated with a significant surgical survival benefit: more severe coronary disease, a worse prognosis with medical therapy, and a more recent operative date. Patients with more extensive coronary obstruction had the greatest improvement in survival. Patients with a poor prognosis because of factors such as older age, severe angina, or left ventricular dysfunction had a reduction in risk that was proportionate to their overall risk on medical therapy. Survival with surgery progressively improved over the study period and by 1984 surgery was significantly better than medical therapy for most patient subgroups. Thus, contemporary coronary revascularization is associated with improved longevity in many patients with ischemic heart disease, especially in those with adverse prognostic indicators.

Age Factors↗
PubMed1989

Current management of mitral valve incompetence associated with coronary artery disease.

At a time when hospital mortality for adult cardiac operations is continuing to fall, the combined mitral valve coronary bypass subset remains at relatively high risk. Efforts to improve results should be directed toward a more general application of mitral reconstruction in this population, tailoring the type of repair to the pathological anatomy of valve dysfunction. Other promising therapeutic measures include the liberal use of reperfusion therapy in the acute papillary muscle dysfunction group, better selection patients for operation, and perhaps operative recommendation to a greater proportion of the more stable patients that previously were treated medically. Finally increasing the general awareness of this problem should hasten the development of improved management strategies.

Coronary Artery Bypass↗
PubMed1989

Effect of acutely increased right ventricular afterload on work output from the left ventricle in conscious dogs. Systolic ventricular interaction.

In seven conscious, chronically instrumented dogs, left ventricular volume was calculated with an ellipsoidal model from the anteroposterior, septal-free wall, and base-to-apex left ventricular dimensions, measured by implanted ultrasonic transducers. Matched micromanometers measured left and right ventricular transmural and transseptal pressures. Ventricular pressures and volumes were varied by inflation of implanted vena caval and pulmonary arterial occluders. When compared with vena caval occlusion at matched left ventricular end-diastolic volumes, graded pulmonary arterial occlusions were associated with higher right ventricular systolic pressures, reduced left-to-right transseptal systolic pressure gradients, and leftward systolic septal displacement, with increased septal-free wall segment shortening (all p less than 0.05). Graded pulmonary arterial occlusions, like vena caval occlusions, reduced left ventricular end-diastolic volume, but left ventricular stroke work at a given end-diastolic volume was greater during pulmonary arterial occlusions (2,674 +/- 380 10(-3) erg) than during vena caval occlusion (1,886 +/- 450 10(-3) erg, p less than 0.05). These data indicate that, while transient pulmonary arterial occlusion reduces left ventricular preload, the concomitant increase in right ventricular systolic pressure, which is the pressure external to the interventricular septal segment of the left ventricle, augments septal shortening and assists left ventricular pump function at a given preload through direct systolic ventricular interaction.

Animals↗
PubMed1989

Ischemic mitral regurgitation.

At a time when hospital mortality for adult cardiac operations is continuing to fall, the ischemic mitral regurgitation subset remains at relatively high risk. Based on analysis of available data, efforts to improve results might be directed toward a more general application of mitral valve reconstruction in this population. Other promising therapeutic measures include the liberal use of reperfusion therapy in the acute papillary muscle dysfunction group, better selection of patients for operation, and, perhaps, operative recommendation to a greater proportion of the more stable patients who previously were treated medically. Incorporating these therapeutic concepts into routine clinical practice may improve the overall prognosis of this difficult subgroup.

Actuarial Analysis↗
PubMed1989

Assessment of left ventricular functional preservation during isolated cardiac valve operations.

To evaluate intraoperative changes in myocardial performance during valvular operations, ventricular functional measurements were obtained in 16 patients before and after elective cardiac valvular replacement. Six patients had mitral regurgitation, four had mitral stenosis, and six had calcific aortic stenosis; all patients underwent isolated mitral or aortic valve replacement. Cold potassium crystalloid cardioplegia, topical hypothermia, and low-flow systemic hypothermia were employed uniformly. Just before and 10 minutes after cardiopulmonary bypass was discontinued, left ventricular pressure and volume data were recorded at four to five different steady-state levels of filling produced by blood infusion or withdrawal from the aortic cannula (mean end-diastolic pressure range, 10-22 mm Hg; mean end-diastolic volume range, 120-168 ml). Portable first-pass radionuclide ventriculography and simultaneous micromanometry were used for construction of left ventricular pressure-volume loops from which stroke work and end-diastolic volume were calculated. Two-dimensional transesophageal echocardiograms also were recorded, and epicardial pacing maintained heart rate as constant as possible. As compared with prebypass measurements, echocardiographic left ventricular wall volume changed insignificantly after the valvular procedures (178-181 ml/m2, p greater than 0.5). The stroke work-end-diastolic volume relationship before and after operation was highly linear in all studies (mean = 0.97). The slope and x intercept of this relationship did not change significantly after operation, indicating a stable level of left ventricular function (from 12.7 x 10(4) to 10.0 x 10(4) ergs/ml and from 67 to 57 ml, respectively; p greater than 0.3).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiopulmonary Bypass↗
PubMed1988

Esmolol and left ventricular function in the awake dog.

Hypotension has been the most frequently reported adverse reaction associated with infusion of the beta 1-adrenergic receptor antagonist esmolol. In some patients, this hypotension has apparently occurred independent of reduction in heart rate or systemic vascular resistance, suggesting decreased stroke volume. In the present study, the preload recuitable stroke work area (PRSWA) model was used to evaluate the negative inotropic effects of esmolol in nine chronically instrumented awake dogs. Left ventricular (LV) transmural pressure and minor axis diameter were measured by micromanometers and sonomicrometry, respectively. Vena caval occlusions were performed so that an analog of stroke work (area within LV transmural pressure-diameter loop) could be measured over a range of preloading conditions during esmolol infusions of 0, 100, 300, 1000, and 3000 micrograms/kg-1.min-1 (n = 9), and at 15 and 30 min after termination of esmolol (n = 8). The linear relationship between stroke work and end-diastolic diameter was characterized for each caval occlusion by a slope and x-intercept. PRSWA was calculated for each caval occlusion as slope/two times the square of the difference between x-intercept and the largest end diastolic diameter observed in the study of a particular dog. Heart rate was different from control (91 +/- 4) only at the highest esmolol dose (127 +/- 4). LV peak positive dP/dt, minor axis ejection shortening, stroke work, and PRSWA were depressed from control at esmolol doses greater than or equal to 300 micrograms.kg-1.min-1. All parameters except dP/dt recovered within 30 min following termination of esmolol.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1988

Quantification of regional myocardial dysfunction after acute ischemic injury.

Quantification of myocardial performance after regional ischemic injury is difficult because available performance indexes are markedly dependent on concurrent load changes. To develop a more load-insensitive index of myocardial function during ischemia, eight conscious dogs were instrumented to measure left ventricular pressure with micromanometers and myocardial segment length with ultrasonic dimension transducers. Preload was varied by transient vena caval occlusion during control conditions, after 15 min of coronary occlusion, and at intervals during 24 h of reperfusion. Acute ischemia shifted the linear relationship between segmental stroke work (SW) and end-diastolic segment length (EDL) rightward, diminishing the slope and increasing the chi-intercept. Preload recruitable work area (PRWA), defined as the area under the SW-EDL curve, reflected changes in both slope and intercept. During acute ischemia, conventional performance indexes and PRWA decreased significantly and required up to 24 h of reperfusion to return to control values. Of all parameters examined, PRWA was most responsive to prolonged ischemic dysfunction after reperfusion and was insensitive to concurrent load changes. Thus PRWA provides improved precision in quantifying of myocardial dysfunction after regional ischemic injury. This parameter should be especially useful in assessing the subtle effects of acute interventions designed to modify functional recovery.

Algorithms↗
PubMed1988

In vivo estimation of left ventricular wall volume in volume-overloaded canine hearts.

Several geometric algorithms have been applied to estimate left ventricular wall volume (Vwall) from two-dimensional echocardiograms but have not been validated in eccentrically hypertrophied hearts. These algorithms can be fitted to the general formula: Vwall = k.Ao.Lo = k.Ai.Li, where Ao and Ai are the outer (epicardial) and inner (endocardial) short-axis areas, Lo and Li are the corresponding long-axis lengths, and k is a constant. The simplifying assumption that Lo and Li are equal yields Vwall = k.Awall.Lo, where Awall = Ao - Ai. In 20 unsedated dogs (10-30 kg), including 10 with aortic regurgitation of 1-18 wk duration, the relationship between actual Vwall (determined postmortem) and Awall.Lo was not significantly different from the line of identity (Vwall = 1.01 Awall.Lo + 0.5 ml, r = 0.98, SEE = 3.5 ml), indicating k was not significantly different from 1. There was no significant difference between predicted and actual Vwall over a range of 31-105 ml, and interobserver variability was 4.1%. The simple area-length product, Awall.Lo, accurately predicts Vwall of both normal and volume-overloaded hypertrophied canine left ventricles and is thus suitable for serial observations of hypertrophic adaptation to volume overload.

Algorithms↗
PubMed1988

Influence of compression rate on initial success of resuscitation and 24 hour survival after prolonged manual cardiopulmonary resuscitation in dogs.

The influence of chest compression rate on initial resuscitation success and 24 hr survival after prolonged manual cardiopulmonary resuscitation (CPR) was investigated in 26 morphine-anesthetized dogs (17 to 30 kg). After placement of aortic and right atrial micromanometers and induction of ventricular fibrillation, manual CPR was commenced immediately and continued for 30 min. One group of 13 dogs underwent manual CPR at a compression rate of 60/min, and the other group at a rate of 120/min. The compression durations in the two groups were not significantly different (51.7 +/- 1.8% at 60/min vs 51.6 +/- 1.9% at 120/min). No drugs other than sodium bicarbonate were administered during CPR. A maximum of three attempts was permitted to defibrillate the heart. Successfully defibrillated animals were followed for 24 hr, during which time no treatment, other than naloxone, was given to reverse the effects of morphine. Arterial blood pH, PCO2, and PO2 were not significantly different in the two groups throughout the CPR period. When compared with the compression rate of 60/min, the compression rate of 120/min produced more successfully defibrillated animals (12/13 at 120/min vs 2/13 at 60/min, p less than .002) and more 24 hr survivors (8/13 at 120/min vs 2/13 at 60/min, p less than .03). All 24 hr survivors were conscious and able to sit, stand, and drink normally. One 24 hr survivor in each group had difficulty walking. Improved survival with the high-rate compression technique was consistent with the significantly higher mean aortic (systolic and diastolic) and coronary perfusion pressures attained with high-rate compressions (all p less than .002). Although the clinical applicability of these findings has yet to be demonstrated, they provide empirical support for the recent decision to increase the chest compression rate for manual CPR recommended by the American Heart Association, and indicate that the hemodynamic and survival benefits of faster compression rates in this experimental preparation were not dependent on covariant alterations in compression duration.

Animals↗
PubMed1988

Current prognosis of ischemic mitral regurgitation. Implications for future management.

Ischemic mitral regurgitation is a serious and increasingly common clinical disorder, but at present, little is known of the associated prognostic implications, especially in specific therapeutic subgroups. Over a 6.5-year period beginning January 1, 1981, postinfarction mitral regurgitation was demonstrated ventriculographically in 2,343 (19%) of 11,748 patients having significant coronary artery disease defined at cardiac catheterization. Moderate or severe regurgitation was observed in 381 (3%), and among these patients, four treatment groups were defined: Group I (medical, n = 165), Group II (reperfusion, n = 63), Group III (coronary artery bypass only, n = 94), and Group IV (valve replacement or repair in addition to coronary bypass, n = 59). Multivariable regression analysis of survival data in the overall population and in specific treatment groups was performed with the Cox proportional hazards model. Defined and undefined selection biases precluded formal quantitative survival comparisons among some treatment groups; however, unadjusted and adjusted survival analysis for each group revealed several interesting concepts. First, increasing severity of mitral regurgitation had a progressively negative impact on survival prognosis regardless of treatment. Congestive heart failure, the number of associated disorders, acute presentation requiring cardiac care unit admission, diminished ejection fraction, increasing coronary obstruction, and advanced age all worsened prognosis (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Immediate versus delayed coronary grafting after streptokinase treatment. Postoperative blood loss and clinical results.

Of all patients with acute evolving myocardial infarction treated surgically at Duke University Medical Center between 1984 and 1986, 27 patients given high doses (greater than 1.5 million units) of streptokinase preoperatively were studied. Eleven patients who received streptokinase had coronary bypass grafting 12 hours after thrombolytic therapy (early hours), eight patients between 12 and 72 hours (delayed), and eight patients beyond 72 hours (late hours). Seventeen patients who underwent coronary bypass grafting within 6 hours of the onset of symptoms, without preoperative streptokinase, were included as control patients. Only the patients having early operation had significantly greater postoperative blood loss; postoperative use of red blood cells; fresh-frozen plasma; cryoprecipitate; prolonged postoperative prothrombin time; and prolonged partial thromboplastin time. Patients having delayed or late operations did not differ significantly from patients not receiving streptokinase. Only the interval between time of streptokinase administration and operation could account for the coagulopathy and the postoperative bleeding complications in the early group. Patients in the early group had a higher in-hospital mortality (27% versus 6% for the non-streptokinase group) and major noncardiac morbidity (36% versus 12% for the non-streptokinase group). Patients in the delayed and late groups had minimal postoperative complications and no mortality. Observations were not explained by differences in total ischemic time, number of angioplasty failures, or number of patients with cardiogenic shock between the early group and the non-streptokinase group. Postoperative bleeding and massive use of blood products seemed to be contributory factors: Two of three deaths in the patients having early operations were associated with clinical suspicion of tamponade. Patients undergoing coronary bypass grafting within 12 hours of streptokinase therapy appear to be a high-risk group in a more emergent, uncontrolled clinical setting and require aggressive monitoring and correction of coagulopathy.

Blood Coagulation Disorders↗
PubMed1988

Beneficial effects of endotracheal extubation on ventricular performance. Implications for early extubation after cardiac operations.

Early endotracheal extubation has been shown to be a safe postoperative management option in patients having cardiac operations. However, few objective data exist on the response of ventricular performance to early termination of controlled ventilation. Seven patients undergoing routine elective coronary artery bypass grafting or adult repair of atrial septal defect were studied after intraoperative placement of left ventricular micromanometers, left ventricular minor axis dimension crystals, and left atrial and intrapleural pressure catheters. Physiologic data were recorded intraoperatively, during controlled mandatory ventilation in the intensive care unit, and during spontaneous respiration immediately after extubation. Extubation to spontaneous breathing was associated with a significant decline in intrapleural pressure and significant increases in left ventricular end-diastolic diameter, ejection diameter shortening, stroke work, and cardiac output. The augmented left ventricular diastolic filling seemed to result from the fall in intrapleural pressure and perhaps from normalization of right ventricular afterload. The preload recruitable stroke work relationship showed that myocardial contractility remained constant after extubation, and ventricular function improved primarily because of increased preload associated with shifting of the capacitance blood volume toward the chest. Thus endotracheal extubation enhances cardiac performance after uncomplicated cardiac surgical procedures, and by this mechanism early extubation may be clinically beneficial as a routine adjunct to postoperative care.

Cardiac Output↗
PubMed1988

Surgical survival benefits for coronary disease patients with left ventricular dysfunction.

Controversy still exists about the proper selection of patients with coronary artery disease and left ventricular dysfunction for coronary bypass surgery. To examine this issue, we studied 710 patients with significant coronary artery disease and left ventricular dysfunction (ejection fraction less than or equal to 40%). Of 301 patients treated surgically, 232 had bypass grafts; 17, left ventricular surgery; and 52, both procedures. At 3 years after treatment, unadjusted survival was 84% for surgical patients and 64% for medical patients. At baseline, medical patients had more left ventricular dysfunction than surgical patients, but surgical patients had more coronary artery disease and angina than medical patients. In Cox survival models, two invasive factors (ejection fraction and extent of coronary artery disease) and three noninvasive indexes (assessment of myocardial infarction, angina, and conduction disturbances) were the five best predictors of survival (p less than 0.001). After adjustment for these factors between the two treatment groups, overall surgical survival at 3 years after treatment was 86%, and medical survival was 68%. Long-term surgical survival benefits appeared greatest in patients with the most severe left ventricular dysfunction, most extensive coronary artery disease, and most severe anginal symptoms. We conclude that surgery provides significant survival benefits for coronary disease patients with left ventricular dysfunction; in general, the sicker the patient, the greater the benefit.

Angina Pectoris↗
PubMed1988

Changing efficacy of coronary revascularization. Implications for patient selection.

To evaluate the potential impact of patient selection for coronary artery bypass graft surgery on long-term survival, the outcomes of 5,809 consecutive patients with symptomatic coronary disease documented by angiography at Duke University Medical Center were examined. Over the entire study period (1969-1984), surgical therapy was associated with improved survival compared with medical therapy whether or not adjustment was made for imbalances in baseline prognostic factors. When patients were categorized according to coronary anatomy and left ventricular function, patients with multivessel disease and poor left ventricular function had a greater long-term survival benefit with surgery than did patients with less coronary artery disease and better left ventricular function. When 5-year survival rates were examined as a function of operative risk, a direct relation was found between estimated operative risk and the medical-surgical survival difference. For patients with an operative risk of 1%, the expected 5-year mortality with surgical therapy was 3% versus 8% with medical therapy (an absolute survival difference at 5 years of 5%). In comparison, for patients with an operative risk of 5%, the expected 5-year mortality with surgery was 10% versus 23% with medical therapy (an absolute survival difference at 5 years of 13%). Over 50% of patients with significant coronary artery disease undergoing cardiac catheterization have an estimated operative mortality risk under 2.5%. These patients would be expected to have a small survival advantage treated surgically. As operative mortality rates are subjected to increasing public scrutiny, selection of low-risk patients will reduce the overall benefit of the operation to the population.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Bypass↗