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Biomedical subjects

J R Pluth

Publications and source records attributed to J R Pluth.

At least 55 records · Page 3Linked to original sources
PubMed1984

Effect of dipyridamole and aspirin on late vein-graft patency after coronary bypass operations.

To study the prevention of occlusion of aortocoronary-artery bypass grafts, we concluded a prospective, randomized, double-blind trial comparing long-term administration of dipyridamole (begun two days before operation) plus aspirin (begun seven hours after operation) with placebo in 407 patients. Results at one month showed a reduction in the rate of graft occlusion in patients receiving dipyridamole and aspirin. At vein-graft angiography performed in 343 patients (84 per cent) 11 to 18 months (median, 12 months) after operation, 11 per cent of 478 vein-graft distal anastomoses were occluded in the treated group, and 25 per cent of 486 were occluded in the placebo group. The proportion of patients with one or more distal anastomoses occluded was 22 per cent of 171 patients in the treated group and 47 per cent of 172 in the placebo group. All grafts were patent within a month of operation in 94 patients in the placebo group and 116 patients in the treated group; late development of occlusions was reduced from 27 per cent in the placebo group to 16 per cent in the treatment group. The results show that dipyridamole and aspirin continue to be effective in preventing vein-graft occlusion late after operation, and we believe that such treatment should be continued for at least one year.

Adult↗
PubMed1984

Hemodynamic effects of calcium chloride injection following cardiopulmonary bypass: response to bolus injection and continuous infusion.

To determine the hemodynamic effects of intravenous injection of calcium chloride, 26 patients were studied immediately after termination of extracorporeal circulation. Eighteen patients (Group A) had injection of a single bolus of CaCl2; in the other 8 patients (Group B), the bolus injection was followed by infusion of CaCl2 at a rate of 1.5 mg/kg/min for 10 minutes. Myocardial contractile element velocity (Vpm), aortic blood flow, electrocardiograms, and left ventricular, systemic arterial, pulmonary arterial, and left atrial pressures were recorded continuously. The baseline ionized calcium level after bypass was 3.6 +/- 0.6 mg/100 ml (normal range, 3.9 to 4.5 mg/100 ml); this increased to 5.4 +/- 0.5 mg/100 ml 1 minute after CaCl2 injection. The ionized calcium level was 4.7 +/- 0.6 mg/100 ml 6 minutes after CaCl2 injection in Group A, and was 5.9 +/- 0.2 mg/100 ml and 6.4 +/- 0.2 mg/100 ml at 6 and 10 minutes, respectively, in Group B. There was significant early hemodynamic improvement after CaCl2 injection, including increases in Vpm (p less than 0.001), cardiac index (p less than 0.001), mean blood pressure (p less than 0.01), and stroke volume index (p less than 0.001). A similar pattern of hemodynamic response was observed in both groups. Approximately 1 minute after CaCl2 injection, cardiac index returned to control level, Vpm and mean blood pressure remained elevated, and heart rate declined (p less than 0.01). Systemic vascular resistance gradually increased and was significantly elevated (p less than 0.05) in Group B at 3 minutes and in Group A at 6 minutes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Intracellular calcium transients in human working myocardium as detected with aequorin.

The calcium transients associated with contraction in human working myocardium were recorded by use of the bioluminescent protein, aequorin, a substance that emits light when it combines with calcium ion (Ca++). Small amounts of aequorin were microinjected into superficial cells of human atrial and ventricular muscle obtained from tissue routinely excised and discarded at the time of cardiac surgery. Light output, an index of intracellular Ca++, and isometric tension development were recorded at 37.5 degrees C at 1 to 5 second intervals of stimulation. Light increases much more quickly than tension and decreases toward basal levels by the time that peak tension is reached. The configuration and time course of the aequorin signal in human myocardium and its responses to inotropic interventions are similar to those recorded in lower mammalian species. The calcium transient appears to be dominated by the release and uptake of Ca++ from intracellular stores under all conditions studied. These results indicate that aequorin is a useful tool for studying the effects of drugs and disease states on cardiac excitation-contraction coupling in human beings as well as in lower animals.

Aequorin↗
PubMed1984

Aortic and mitral valve incompetence: long-term follow-up (10 to 19 years) of patients treated with the Starr-Edwards prosthesis.

The long-term course (mean 15 years) of 336 patients with valvular incompetence who underwent Starr-Edwards ball valve implantation between 1962 and 1971 was reviewed. Eighteen patients (10%) with aortic valve replacement and 24 (16%) with mitral valve replacement died early postoperatively. Mortality remained high (31%) in the first 3 years after aortic valve replacement; it was highest (13%) in the first year after mitral valve replacement and then approached the normal rate. The most common mode of death was sudden death after aortic and cardiac failure after mitral valve replacement. At follow-up, 76% of survivors had improved symptomatically. Three instances of primary valve malfunction occurred. The probability of freedom from thromboembolism at 15 years postoperatively was 56% for aortic valve replacement and 52% for mitral valve replacement. The Starr-Edwards valve prosthesis is durable over prolonged follow-up period, but thromboembolism remains a persistent problem. Survival may be normal for patients surviving the early postoperative years.

Adolescent↗
PubMed1984

Surgery for tricuspid regurgitation late after mitral valve replacement.

Tricuspid valve insufficiency may contribute to a poor hemodynamic result after mitral valve replacement. To determine the role of surgical treatment, we have reviewed the records of 32 adult patients who underwent tricuspid valve repair or replacement 4 months to 14 years after mitral valve replacement. Mild tricuspid valve insufficiency at the time of mitral valve replacement was present in 21 patients (66%); 26 patients (81%) had New York Heart Association class IV disability. Tricuspid annuloplasty was performed in 16 patients, and the remainder received various prosthetic valves. Concomitant repair of mitral valve periprosthetic leak and/or replacement of the aortic valve was necessary in 18 patients (53%). Hospital mortality was 25%, and all early deaths were related to low cardiac output. Among hospital survivors there have been 14 late deaths for 3 and 5 year actuarial survival rates of 65% and 44%. Twelve of the 14 patients who died late and one of 10 patients who were alive at the end of the follow-up period had little or no functional improvement after tricuspid valve repair or replacement. The high early and late mortality and poor functional outcome for patients undergoing tricuspid valve surgery late after mitral valve replacement contrast with our good overall results in reoperation for prosthetic heart valves. It appears that serious tricuspid valve insufficiency after mitral valve replacement frequently signals right ventricular failure and dilatation; restoring valve competence is palliative. This experience encourages us to continue our policy of liberal indications for tricuspid valve annuloplasty at initial mitral valve replacement.

Adult↗
PubMed1983

Trial of combined warfarin plus dipyridamole or aspirin therapy in prosthetic heart valve replacement: danger of aspirin compared with dipyridamole.

Despite the use of oral anticoagulation in patients with prosthetic heart valves, persistent thromboembolism over time warrants a search for improved methods of prevention. Thus, patients receiving 1 or more mechanical prosthetic heart valves were randomized to therapy with warfarin plus dipyridamole (400 mg/day) or warfarin plus aspirin (500 mg/day) on the basis of location and type of valve and surgeon, and followed up with a concurrent, nonrandomized control group taking warfarin alone. In 534 patients followed up 1,319 patient-years, excessive bleeding (necessitating blood transfusion or hospitalization) was noted in the warfarin plus aspirin group (23 of 170 [14%], or 6.0/100 patient-years) compared with warfarin plus dipyridamole (7 of 181 [4%], or 1.6/100 patient-years, p less than 0.001), or warfarin alone (9 of 183 [5%], or 1.8/100 patient-years, p less than 0.001). A trend was evident toward a reduction in thromboembolism in the warfarin plus dipyridamole group (2 of 181 [1%], or 0.5/100 patient-years) as compared with warfarin plus aspirin (7 of 170 [4%], or 1.8/100 patient-years), or warfarin alone (6 of 183 [4%], or 1.2/100 patient-years). Adequacy of anticoagulation (based on 12,720 prothrombin time determinations) was similar in all 3 groups with 65% of prothrombin times in the therapeutic range (1.5 less than or equal to prothrombin time/control less than or equal to 2.5), 30% too low, and 5% too high. Warfarin plus aspirin therapy resulted in excessive bleeding and is contraindicated. Longer follow-up study is needed to determine whether further separation of the incidence of thromboembolism can be detected.

Aspirin↗
PubMed1983

Clinical evaluation of a sutureless cardiac pacing lead: chronic threshold changes and lead durability.

Chronic threshold changes and durability of the Medtronic 6917 sutureless cardiac pacing lead were evaluated in 100 consecutive patients. A bipolar pacing system was established in each patient. Lead failure occurred in 4 patients; all failures resulted from exit block or loss of adequate contact between electrode and myocardium. Electrode fracture or loss of lead insulation was not observed. Fifty patients had replacement of the pulse generator 27.4 +/- 1.8 months after implantation. Long-term stimulation threshold voltage was about 2.5 times greater and current was about 3.5 times greater than values obtained at initial implantation, yet they continued to permit safe and effective cardiac pacing.

Adolescent↗
PubMed1983

Results of reoperation for periprosthetic leakage.

Between 1961 and 1978, 6,602 valves were replaced in 5,660 patients. Reoperation for periprosthetic leakage was performed in 105 patients (1.6% of the valves); early mortality was 5.7%. At reoperation, 52% of patients were in New York Heart Association Classes III and IV, whereas 72% had been in Classes III and IV prior to the primary valve replacement. Seventy-five patients had aortic periprosthetic leaks, which were distributed equally around the annulus. Among these patients, 41 (55%) had aortic valve rereplacement and 34 (45%) had suture repair. At 5 years, the survival was 94% and the event-free survival was 71%. Seventeen patients had multiple aortic valve reoperations. Hospital mortality for the second reoperation was 5.8%. At late follow-up, 19 patients had murmurs of residual or recurrent aortic periprosthetic leakage. Twenty-nine patients had mitral periprosthetic leaks, most often near the anterior leaflet. Eight patients had mitral valve rereplacement, and 21 had suture repair. At 5 years, the survival was 75% and the event-free survival was 52%. Four patients underwent multiple reoperations. At late follow-up, 5 of the 29 patients in the mitral valve group had murmurs of residual or recurrent periprosthetic leakage. One patient had tricuspid valve rereplacement. The low hospital mortality and the good late results have encouraged us to recommend an aggressive approach in the correction of periprosthetic leakage in all symptomatic and selected asymptomatic patients.

Adult↗
PubMed1983

Simplified method of heterotopic cardiac transplantation for left ventricular assist.

A method of heterotopic cardiac transplantation has been developed which is performed through a left thoracotomy and requires only two vascular anastomoses. Systemic heparinization and cardiopulmonary bypass are not necessary. Preliminary experiments demonstrated that this heterotopic transplant technique was effective for left ventricular assist; in some experiments, a multimode atrioventricular programmable pacemaker was used to provide sequential pacing for "counterpulsation." This technique or similar techniques may have potential clinical benefit for patients with intractable left ventricular failure.

Animals↗
PubMed1983

The morbidity and mortality of reoperation for coronary artery disease and analysis of late results with use of actuarial estimate of event-free interval.

To determine late survival and functional status after second revascularization procedures for coronary artery disease, we studied 106 consecutive patients operated on between June, 1969, and December, 1980. The mean age of the 96 men and 10 women was 49 +/- 8 years (range 22 to 65 years). Before reoperation, 101 patients (95%) were judged to be in New York Heart Association Class III or IV with angina, and 81 patients (76%) had three-vessel involvement. Angina recurrence was most commonly caused by bypass graft occlusion alone and in combination with progressive disease of the native arteries (60 patients, 57%). Three patients (2.8%) died within 30 days of reoperation; each death resulted from myocardial infarction. An average of 2.2 coronary arteries were bypassed in each patient. Complete follow-up data (mean 43 months) were available for 105 patients. Actuarial survival of patients dismissed alive is 94% at 5 years and 89% at 7 years. All late cardiac-related deaths occurred in patients with three-vessel disease. When recurrence of any angina, need for a third operation, and myocardial infarction are included with cardiac-related deaths, event-free survival is 28% at 5 years and 26% at 7 years. Late survival and functional status could not be predicted by the cause of recurrent angina or the presence of risk factors. Repeat myocardial revascularization can apparently be undertaken with low risk and with prospects for excellent long-term survival. After reoperation, recurrence of mild angina is not uncommon, but freedom from serious cardiac events and relief of severe symptoms were noted in more than 60% of patients 5 years later.

Actuarial Analysis↗
PubMed1983

Reoperation on prosthetic heart valves. An analysis of risk factors in 552 patients.

Five hundred fifty-two patients underwent a total of 617 reoperations for repair or replacement of a prosthetic heart valve. Operative mortality for first reoperation (530 patients) was 5.9% for the aortic position and 19.6% for the mitral position. Overall operative mortality was 14% for second reoperation (69 patients) and 7% for third reoperation (14 patients). In addition to valve position, operative mortality for first reoperation appeared to be related to pre-reoperation functional class and urgency of operation. First reoperation for mitral valve patients in New York Heart Association (NYHA) Class II was 4.2%; for Class III, 9.3%; and for Class IV, 41%. In the aortic position, operative mortality was 2.4% for Class I, 1.6% for Class II, 6.3% for Class III, and 20.8% for Class IV. The mortality for elective mitral valve reoperation was 0%; for urgent operation, 20.3%; and for emergency procedures, 54.5%. Elective aortic valve reoperation carried a 1.4% mortality; urgent procedures, 8%; and emergency procedures, 37.5%. No significant differences in bleeding complications were noted between reoperations and initial valve replacement. The data appear to suggest that when significant valve dysfunction is first noted, reoperation should be undertaken to minimize operative risk.

Adolescent↗
PubMed1983

Enlargement of the aortic root or anulus with autogenous pericardial patch during aortic valve replacement. Long-term follow-up.

Patch enlargement of the aortic root or anulus is a widely accepted technique when restrictive anatomy is encountered during aortic valve replacement. Patches made of prosthetic material have been used almost exclusively, and patches of autogenous pericardium have not received wide acceptance. Although pericardium is advantageous because of its low cost, ready availability, and ease of handling, its long-term durability has not been fully established. From 1965 to 1981, 96 patients had autogenous pericardial patches placed during aortic valve replacement at the Mayo Clinic. In 81 patients, the patches were placed solely in a supravalvular position to facilitate aortic closure, while in 15 patients, the patches were placed in both subvalvular and supravalvular positions, allowing for annular expansion and insertion of a larger prosthesis. In a mean follow-up of 5.4 years, none of the 92 operative survivors has had clinical evidence of sudden patch failure and none has had patch aneurysms detected by routine chest roentgenography. One patient required reoperation for a perivalvular leak at the point where the prosthesis had been sutured to the patch. Objective data concerning the late postoperative status of the patch were available on 48 patients: 24 underwent reoperation, 16 underwent two-dimensional echocardiography, two underwent aortic root angiography, and six underwent postmortem examination. Patch aneurysms were universally absent, and in every patient the patches were well incorporated into the adjacent tissues. This proven durability suggests that autogenous pericardium is a satisfactory patch material when required during aortic valve replacement.

Adolescent↗
PubMed1982

Cardiac-catheterization and cardiac-surgical facilities: use, trends, and future requirements.

Cardiac catheterizations and cardiac operations were evaluated in the population of Olmsted County, Minnesota, from 1973 through 1980, and trends in this region were compared with nationwide trends based on data from several sources. The rates of coronary arteriography and coronary-artery bypass operations in Olmsted county have increased over time, but overall, the rates of catheterization and operation appeared to be leveling off. For the country as a whole, the data appear to show similar trends, but there are wide differences among regions in the rates of operation and catheterization. In 1980 40 per cent of hospitals with cardiac-catheterization laboratories and 55 per cent of those with facilities for open-heart surgery were doing fewer than the suggested minimum numbers of these procedures necessary to achieve optimum results. The data support the view that further growth in the number of cardiac centers should be avoided. We believe there is a need for continued evaluation of the use of cardiac services if quality is to be protected and costs controlled.

Adult↗
PubMed1982

A platelet-inhibitor-drug trial in coronary-artery bypass operations: benefit of perioperative dipyridamole and aspirin therapy on early postoperative vein-graft patency.

To prevent occlusion of aortocoronary-artery-bypass grafts, we conducted a prospective, randomized-double-blind trial comparing dipyridamole (instituted two days before operation) plus aspirin (added seven hours after operation) with placebo in 407 patients. Vein-graft angiography was performed in 360 patients (88 per cent) within six months of operation (median, eight days). Within one month of operation, 3 per cent of vein-graft distal anastomoses (10 of 351) were occluded in the treated patients, and 10 per cent (38 of 362) in the placebo group; the proportion of patients with one or more distal anastomoses occluded was 8 per cent (10 of 130) in the treated group and 21 per cent (27 of 130) in th placebo group. This benefit in graft patency persisted in each of over 50 subgroups. Early postoperative bleeding was similar in the two groups. In this trial dipyridamole and aspirin were effective in preventing graft occlusion early after operation.

Adult↗