Biomedical subjects
Publications and source records attributed to F D Loop.
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Among 500 patients consecutively undergoing primary aortic valve replacement combined with coronary bypass grafting from 1967 to 1981, there were 29 (5.8%) perioperative deaths. Follow-up of the late survivors ranged from 43 to 181 months (mean 85 months); actuarial survival rates were 88%, 77%, and 52% and event-free survival rates were 80%, 65%, and 32% at 2, 5, and 10 postoperative years. Cox proportional hazard analyses were used to identify determinants of late risk. Patient-related variables associated with decreased late survival rates included advanced age, cardiothoracic ratio 50% or greater, and preoperative New York Heart Association class III or IV symptoms. Moderate or severe impairment of left ventricular function as determined by angiography and advanced age were variables that decreased late event-free survival rates. Patients with bioprostheses had better survival rates (p less than 0.001) and event-free survival rates (p = 0.012) than did patients with mechanical valves. Analyses of subgroups according to the type of valve and postoperative anticoagulant management showed that both survival and event-free survival rates were decreased for patients with mechanical valves who were not taking warfarin and were enhanced for patients with bioprostheses who were not taking warfarin.
The risk of bilateral internal mammary artery grafting was studied in three groups of patients who were computer matched for recognized risk factors: year of operation, age, gender, extent of coronary artery disease, left ventricular function, completeness of myocardial revascularization, and history of congestive heart failure. The patient groups differed in the fact that they received veins only, one internal mammary artery graft, or two internal mammary artery grafts. The operative mortality rates for these three groups were 1.8%, 0.3%, and 0.9%, respectively (no significant difference). Analysis of perioperative morbidity demonstrated no significant differences except for a slight increase in transfusion requirements in the group receiving two internal mammary artery grafts (p = 0.04). None of the patients with only vein grafts had wound complications. One patient in the group with one internal mammary artery graft had a wound complication (0.03%). Eight patients receiving two internal mammary artery grafts had wound complications (2.4%) (p = 0.002). The prevalence of wound complications in patients with diabetes mellitus was 5.7% and in those without diabetes mellitus, 0.3% (p = 0.01). The prevalence of wound complications in patients less than 60 years of age was 0.2%, in patients in their 60s, 1.6%, and in patients older than 70, 3.1% (p = 0.01). Multivariate logistic regression analysis identified diabetes mellitus and age and not bilateral internal mammary artery grafting as risk factors for wound complications. We conclude that bilateral internal mammary artery grafting does not increase surgical mortality and increases surgical morbidity by a slight increase in the mean transfusion requirement.
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Previous investigations have suggested that Doppler echocardiography is useful in detecting dysfunction in aortic (AVR) and mitral prostheses (MVR). However, to diagnose abnormalities, the spectrum of normal velocities through these valves must be established. Therefore, we used Doppler echocardiography to study 100 patients with 105 prosthetic valves that had no clinical evidence of valve dysfunction 9 +/- 8 days postoperatively. There were 66 Carpentier-Edwards (C-E), 23 St. Jude (S-J), and 16 Ionescu-Shiley (I-S) valves. In 70 AVR, the peak instantaneous gradient was 26.4 +/- 8.2 Hg, mean systolic gradient was 15.6 +/- 5 mm Hg, and gradients varied inversely with valve size, although differences were significant only when comparing the smallest vs the largest valve sizes (p less than or equal to 0.03). Peak instantaneous gradients greater than 36 mm Hg occurred only in AVR size 23 or smaller. There were no significant differences in gradients among C-E, S-J, and I-S AVR. In 35 MVR, mean gradient was 6.9 +/- 2.3 mm Hg and valve area was 2.7 +/- 0.8 cm2; neither varied significantly with valve size. However, S-J MVR group had smaller mean gradients and larger effective valve area than C-E bioprosthetic MVR (p = 0.01 and p = 0.05, respectively). Regurgitation was more common in AVR (26%) than in MVR (9%), p = 0.04, although all instances were mild and clinically silent. We conclude that normal AVR and MVR of a given size and type have a predictable range of Doppler echocardiographic parameters. Doppler evidence of mild regurgitation is a frequent finding in normal AVR and MVR.(ABSTRACT TRUNCATED AT 250 WORDS)
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Responding to a survey about their practice in 1985, 2,969 (70%) Board-certified thoracic surgeons provided data that were compared with data from manpower surveys in 1980 and 1976. (table; see text) Thoracic surgeons were most active between ages 35 and 54 years when they accomplished 61% of all general thoracic and 85% of cardiac operations. Surgeons older than 50 years performed significantly more general thoracic operations than younger surgeons, and the younger group performed significantly more cardiac operations than their older counterparts. Solo practice continued to decline. In smaller referral areas, the number of general thoracic procedures per surgeon increased, but the number of cardiac operations have decreased compared with 1980. Overall, general thoracic and cardiac operations increased, but peripheral vascular procedures and pacemaker insertions decreased in almost all nine census regions. Fewer general thoracic and cardiac operations were performed per thoracic surgeon in the western United States than in central and eastern regions. In response to questions about work load, 55% believed that their clinical activity was satisfactory, 42% operated too little, and 3% operated too much. The 363 non-Thoracic Board-certified surgeons who responded performed 14% of general thoracic and 8% of cardiac surgery in 1985. During the first half of the 1980s, our specialty certified an average of 134 thoracic surgeons annually, which is higher than the 120 surgeons per year estimated to meet the projected demand.
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Fifteen hundred consecutive patients undergoing a first reoperation for coronary revascularization were reviewed to determine early and late results and predictors of survival. Patients were subdivided into cohorts on the basis of the year of reoperation: Group A (1967 to 1978, 436 patients); Group B (1979 to 1981, 439 patients); and Group C (1982 to 1984, 625 patients). Overall operative mortality was 3.4% (51 deaths): 4.6%, 2.3%, and 3.4% for Groups A, B, and C, respectively. Group C had significantly more women (p = 0.01) and patients with triple-vessel disease, left main coronary artery stenosis (greater than or equal to 50%), abnormal left ventricular function, age greater than or equal to 70 years, and graft failure as a surgical indication (all p less than 0.001). The mean interval between operations increased from 50 months for Group A to 84 months for Group C. At reoperation, Group C patients received more grafts, more internal mammary artery grafts, and had a higher prevalence of complete revascularization (all p less than 0.001). Univariate and multivariate analyses identified left main stenosis (p less than 0.0001), Class III or IV symptoms (p = 0.0002), advanced age (p = 0.0006), Group A (p = 0.02), and incomplete revascularization (p = 0.004) as predictors of increased in-hospital mortality. Follow-up of in-hospital survivors (mean interval 54 months, range 13 to 171 months) documented a 5 year survival rate of 90% and a 10 year survival rate of 75%. Multivariate testing identified advanced age (p less than 0.0001), hypertension (p less than 0.0001), and abnormal left ventricular function (p less than 0.0001) as predictors of decreased late survival.
The goal of providing patent grafts distal to important coronary stenoses remains unchanged. Results of bypass grafting show the influence of refined technique, improved technology, and the longer followup now available. Coronary artery bypass is now routinely performed with low morbidity and mortality. Late attrition of saphenous vein grafts with concomitant deterioration of patients' clinical status has been increasingly recognized. The internal mammary graft, with its superior patency and impact on length and quality of survival, is gaining wider acceptance. Increased use of the mammary artery graft and extension of its use with bilateral and sequential grafting patterns are an important trend in the current practice of coronary surgery.
Fifty-three patients underwent reoperation for open mitral commissurotomy (OMC) with one (1.9%) in-hospital death. The previous mitral operation was an OMC in 14 patients and a closed commissurotomy in 39. Mean age at the time of repeat OMC was 46 years (range 27 to 64), and NYHA functional class was II in 19 patients, III in 31, and IV in three. Follow-up of the 52 in-hospital survivors at a postoperative interval of 1 to 23 years (mean 10) documented 13 late deaths (mean interval 117 months, range 17 to 209) and survival of 96%, 83%, and 63% at 5, 10, and 15 postoperative years, respectively. Sixteen patients underwent subsequent mitral valve surgery (one OMC and 15 mitral valve replacements) 1 to 223 months after repeat OMC (mean 99), three patients within 5 years of repeat OMC. Reoperation-free survival was 94%, 74%, and 52% at 5, 10, and 15 postoperative years, respectively. Univariate testing did not document any correlation between age, functional class, rhythm, and either survival or reoperation-free survival. When feasible, repeat OMC can afford patients excellent long-term survival and relative freedom from prosthetic valve replacement.
We compared patients who received an internal-mammary-artery graft to the anterior descending coronary artery alone or combined with one or more saphenous-vein grafts (n = 2306) with patients who had only saphenous-vein bypass grafts (n = 3625). The 10-year actuarial survival rate among the group receiving the internal-mammary-artery graft, as compared with the group who received the vein grafts (exclusive of hospital deaths), was 93.4 percent versus 88.0 percent (P = 0.05) for those with one-vessel disease; 90.0 percent versus 79.5 percent (P less than 0.0001) for those with two-vessel disease; and 82.6 percent versus 71.0 percent (P less than 0.0001) for those with three-vessel disease. After an adjustment for demographic and clinical differences by Cox multivariate analysis, we found that patients who had only vein grafts had a 1.61 times greater risk of death throughout the 10 years, as compared with those who received an internal-mammary-artery graft. In addition, patients who received only vein grafts had 1.41 times the risk of late myocardial infarction (P less than 0.0001), 1.25 times the risk of hospitalization for cardiac events (P less than 0.0001), 2.00 times the risk of cardiac reoperation (P less than 0.0001), and 1.27 times the risk of all late cardiac events (P less than 0.0001), as compared with patients who received internal-mammary-artery grafts. Internal-mammary-artery grafting for lesions of the anterior descending coronary artery is preferable whenever indicated and technically feasible.
Using pusher-plate-type artificial hearts, changes in the degree of synchrony and stroke volume were compared to phase and amplitude calculations from the first Fourier component of individual-pixel time-activity curves generated from gated radionuclide images (RNA) of these hearts. In addition, the ability of Fourier analysis to quantify paradoxical volume shifts was tested using a ventricular aneurysm model by which the Fourier amplitude was correlated to known increments of paradoxical volume. Predetermined phase-angle differences (incremental increases in asynchrony) and the mean phase-angle difference calculated from RNAs showed an agreement of -7 degrees +/- 4.4 degrees (mean +/- SD). A strong correlation was noted between stroke volume and Fourier amplitude (r = 0.98; P less than 0.0001) as well as between the paradoxical volume accepted by the 'aneurysm' and the Fourier amplitude (r = 0.97; P less than 0.0001). The degree of asynchrony and changes in stroke volume were accurately reflected by the Fourier phase and amplitude values, respectively. In the specific case of ventricular aneurysms, the data demonstrate that using this method, the paradoxically moving areas may be localized, and the expansile volume within these regions can be quantified.
Pituitary apoplexy occurred in 3 patients in the immediate postoperative period following cardiac operation with cardiopulmonary bypass. In this setting, this complication is extremely rare and not widely recognized. Precipitating factors may be related to the extracorporeal bypass apparatus, anticoagulation, low cerebral blood flow, and even anesthetic agents. Neurosurgical decompression can be safely performed in the early postoperative period following open-heart operations.
One thousand consecutive cardiac reoperations for valve surgery in 897 patients were reviewed to determine in-hospital mortality and indicators of risk. Subgroups based on the number of previous cardiac procedures and the valve or valves replaced or repaired at reoperation (aortic valve, mitral valve, tricuspid valve, or multiple valves and mortality [deaths/number of procedures (% mortality)]) for those subgroups are as follows: (Table: see text) Predictors of increased risk for a first aortic valve reoperation were advanced age (p = .0002), endocarditis (p = .0018), female sex (p = .014), impaired left ventricular function (p = .039), and number of coronary vessels obstructed by 70% or more (p = .055). For a first mitral valve reoperation, the predictors were advanced age (p less than .0001), preoperative shock or cardiac arrest (p = .01), previous aortic or tricuspid valve operations (p = .02), type of mitral valve procedure (risk for repair of periprosthetic leak was greater than mitral valve replacement which was greater than mitral valve-conserving operation [p = .05]), and impaired left ventricular function (p = .059). For a first multiple valve reoperation, the predictors were diabetes (p = .04) and ascites (p = .02), whereas patients undergoing mitral valve replacement and tricuspid valve operations were at decreased risk (p = .01). Comparison of second reoperations with first reoperations indicates risk increases for multiple operations (p = .01) but not for aortic or mitral valve procedures. Rereplacement of a prosthesis (p = .007), coronary bypass grafting at reoperation (p = .006), and advanced age (p = .06) increased the risk for second reoperations. Age is the most consistent predictor of risk for patients undergoing valve reoperations.
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The saphenous vein has been the traditional conduit for elective myocardial revascularization. Although readily available and adaptable to many configurations around the heart, it is prone to intimal hyperplasia and vein graft atherosclerosis, which diminish long-term patency and relief of symptoms. The internal mammary artery graft represents a marked improvement over the saphenous vein graft in many respects. Data are presented comparing saphenous vein graft patency with that of the internal mammary artery, bilateral internal mammary artery, free internal mammary artery, and sequential internal mammary artery grafts.
Free internal mammary artery grafts were placed in 156 patients (1971 to 1985). Preoperative clinical and angiographic variables were similar to those of other series of isolated coronary bypass grafts. Of 244 total internal mammary artery grafts, 166 were in the aorta-coronary position and were performed mainly because of unsuitable saphenous veins or to gain additional graft length. One patient (0.6%) died during hospitalization. Perioperative complications included respiratory dysfunction in 16 (10.3%), reoperation for bleeding in 13 (8.0%), stroke in four (2.6%), myocardial infarction in three (1.9%), and wound complications in two (1.3%). Morbidity occurred significantly more often in the 1971 to 1975 period. Subsequently, eight (7%) had reoperation (6 to 158 months; mean 99 months). After a 98 month mean follow-up, the 10 year actuarial survival rate (including all causes of death) was 73.3%. Of 40 free grafts restudied within 18 months of operation, 31 (77%) were patent. The higher rate of early closure is attributed to technical problems early in our experience, especially construction of the aortic anastomosis. However, 32 of 35 (91%) free grafts studied after more than 18 months (mean 94 months) were open. Fifty of 58 (86%) free internal mammary artery grafts placed to the anterior descending coronary artery, seven of nine (78%) to the circumflex, and six of eight (75.0%) to the right coronary artery were patent. Sequential catheterization showed that of 24 free grafts open at 9 months, 24 remained patent at 80 months; when six of these were restudied at 93 months (third catheterization) and two (fourth catheterization) at 125 months, all were patent. These late studies of free internal mammary artery grafts showed no evidence of graft atherosclerosis. Free internal mammary artery grafts, like in situ internal mammary artery grafts, appear to have relative immunity from atherosclerosis. These findings expand the versatility of internal mammary artery grafting and justify wider use of free internal mammary artery grafts.