Biomedical subjects

D N Ross

Publications and source records attributed to D N Ross.

At least 19 recordsLinked to original sources

PubMed1991

Replacement of the aortic valve or root with a pulmonary autograft in children.

Between January 1967 and December 1988, 34 patients ranging in age from 3 to 18 years (mean, 14 +/- 3.6 years) underwent replacement of the aortic valve or root with their own pulmonary valve. The indication for operation was left ventricular outflow obstruction in 16 patients (47%), aortic regurgitation in 14 (41%), mixed aortic valve disease in 3 (9%), and failure of a previously implanted aortic homograft in 1 (3%). There were four early deaths, all before 1971, giving a hospital mortality of 11.8% (70% confidence interval, 6% to 20%). Surviving patients have been followed up a cumulative total of 214 patient-years, the longest period of observation being 16 years 8 months. Late mortality was 13.3% (70% confidence interval, 7% to 23%), and 4 other patients required removal of the pulmonary autograft for endocarditis. Actuarial rates at 16 years were 74% +/- 11% for freedom from reoperation on the left ventricular outflow tract, 80% +/- 10% for freedom from reoperation on the right ventricular outflow tract, and 77% +/- 10% for late survival. There was no instance of primary structural degeneration in the pulmonary autograft, and all surviving patients were in New York Heart Association functional class I without medication. This experience demonstrates that the pulmonary autograft can achieve good early and medium-term results in young patients. Should growth potential be realized, it might constitute the ideal biological valve for the left ventricular outflow in children.

Adolescent↗

PubMed1991

Treatment of complicated prosthetic aortic valve endocarditis with annular abscess formation by homograft aortic root replacement.

The outcome of 30 consecutive patients with active aortic prosthetic valve endocarditis and root abscesses treated by the technique of homograft aortic root replacement with reimplantation of the coronary arteries is detailed. The principles of this technique are the removal of all abscesses and infected areas likely to drain into the infected mediastinum, excision of infected tissues down to healthy noninfected tissue and replacement with an antibiotic-impregnated homograft aortic root. All patients had evidence of progressive cardiac failure and ongoing sepsis. Mean patient age (+/- SD) at the time of operation was 42 +/- 18 years. The mean number of previous aortic valve replacements per patient was 1.6 +/- 0.7; 14 patients (47%) had undergone greater than or equal to 2 previous replacements. At operation, aortic root abscesses were found in all patients; abscess extension to adjacent structures and partial valve dehiscence had occurred in 23. In-hospital death occurred in 9 (30%) of the 30 patients. The 21 hospital survivors have been followed up for a mean of 66 +/- 42 months (range 9 to 144). Overall, 17 (81%) of the 21 hospital survivors have remained free of major adverse events (recurrence of endocarditis, need for reoperation or death). The results of our study suggest that homograft aortic root replacement should be considered favorably in the treatment of patients with aortic prosthetic valve endocarditis and root abscesses.

Abscess↗

PubMed1991

Comparison of the aortic homograft and the pulmonary autograft for aortic valve or root replacement in children.

To assess late results of aortic homograft and pulmonary autograft valves implanted into the left ventricular outflow tract of children, we reviewed the case histories of 146 patients 18 years of age or younger who underwent aortic valve or root replacement between November 1964 and April 1990. One hundred three patients (mean, 12 +/- 3.9 years) received an aortic homograft and 43 (mean, 14 +/- 4.1 years) had their own pulmonary valve transferred to the aortic position. There were 54 valve and 49 root replacements with homografts and 36 valve and seven root replacements with autografts. Hospital mortality rate was 15.5% (16 patients) in the homograft group and 11.6% (five patients) in the autograft group. Survivors were followed up for a total of 867 (homograft) and 297 (autograft) patient-years. The late mortality rate was 16.7% (1.9% per patient-year) for patients with homografts and 13.2% (4.4% per patient-year) for patients with autografts, whereas the incidence for reoperation per patient-year was 2.9% and 2.0%, respectively. At 15 years actuarial rates for homografts and autografts for freedom from reoperation were 54% +/- 8.1% and 68% +/- 11.1%; freedom from endocarditis, 97% +/- 2.4% and 75% +/- 10.2%; and freedom from any complication, 41% +/- 6.5% and 50% +/- 10.3%. Valve degeneration occurred in 19 homografts (2.2% per patient-year), whereas there was no definite instance of primary tissue failure among the pulmonary autografts. This experience would indicate that either the homograft or the autograft valve can be used with acceptable results in children. However, the pulmonary autograft gives better long-term performance and, if growth potential is realized, may be the ideal valve substitute in children.

Adolescent↗

PubMed1989

Viable and nonviable aortic homografts in the subcoronary position: a comparative study.

One hundred fifty-five freeze-dried, 63 frozen, and 337 Hanks'-antibiotic solution preserved or nutrient-antibiotic solution preserved homografts used for isolated aortic valve replacement have been followed for 1 to 20 years (mean, 5.3 years), a total of 2,931 patient-years of follow-up information. Overall survival, valve-related death, primary tissue failure, failure due to surgical technical error, infective endocarditis, and overall event-free survival have been assessed and compared. Overall survival 20 years after operation was 51.6% +/- 8.1% with a low incidence of sudden death. The method and length of preservation did not have any effect on the long-term performance or the mode of failure of the homografts. The rate of primary tissue failure was apparently higher with valves preserved in a solution containing calf serum, but the difference was not significant. It is concluded that long-term patient survival and quality of life after aortic valve replacement with a homograft are excellent. The current study, however, could not verify the existence of a significant difference between the three assessed methods of homograft preservation. Furthermore, it could not prove the importance of cellular viability or the existence of clinically significant immunological factors other than the calf serum content of the nutrient medium.

Adult↗

PubMed1989

Use of an intraaortic balloon pump as a pneumatic ventricular assist device controller.

Using a circulatory analogue, we investigated sequentially the performance of a dedicated ventricular assist device driver and an intraaortic balloon pump when driving a pneumatic ventricular assist device. Each drive device was compared under identical pumping conditions at rates of 40 to 120 cycles/min against two resistances. Our preliminary study showed that a modified intraaortic balloon pump could drive a pneumatic ventricular assist device as effectively as its dedicated driver. The necessary modifications to and possible further development of the intraaortic balloon in this role are discussed.

Assisted Circulation↗

PubMed1988

Heterologous antigenicity induced in human aortic homografts during preservation.

A series of rabbit experiments has been carried out to investigate the potential antigenicity of the heat-treated foetal calf serum which is commonly used to enhance viability of preserved aortic homograft valves. In all presensitised animals, the calf serum content of the nutrient medium which infiltrated the aortic wall during preservation provoked a heavy second-set reaction. It is concluded that heat-treated foetal calf serum is a potent heterologous antigen and should not be used for preserving human tissue selected for transplantation.

Animals↗

PubMed1988

Coarctation of aorta: late aneurysm formation with Dacron onlay patch grafting.

Repair of coarctation of the aorta using Dacron onlay patch grafting performed in a 2 1/2-year-old child, with subsequent late formation of a true aneurysm on the side of the graft, is reported. Review of the literature did not reveal other cases of late formation of true aneurysm on the side of the Dacron onlay patch graft.

Aortic Aneurysm↗

PubMed1988

Long-term performance of 555 aortic homografts in the aortic position.

Long-term results with 555 aortic homografts used for isolated aortic valve replacement (AVR) between 1964 and 1986 were analyzed to assess valve performance and the time-related onset of valve-related events. The total follow-up was 2,931 patient-years. Twenty years after operation, overall survival was 51.6 +/- 8.1%, freedom from valve-related death was 67.1 +/- 8.9%, freedom from primary tissue failure was 12.4 +/- 4.8%, freedom from infective endocarditis was 82.7 +/- 4.3%, freedom from surgical technical failure was 88.1 +/- 2.3%, and freedom from all complications including valve-related death was 9.0 +/- 3.5%. The incidence of thromboembolism was 0.034% per patient-year (one potential event). Long-term results after homograft insertion for aortic stenosis were significantly better than those after insertion for aortic incompetence. It is concluded that the good quality of life and the median life expectancy, which extends more than 20 years after operation, make the homograft an excellent choice for AVR.

Actuarial Analysis↗

PubMed1988

Antibiotic prophylaxis in cardiac surgery: a prospective comparison of two dosage regimens of teicoplanin with a combination of flucloxacillin and tobramycin.

Teicoplanin, a new glycopeptide antibiotic, has a serum half-life of 47 h and excellent activity against Gram-positive bacteria, including methicillin resistant staphylococci, making it a potentially useful drug for cardiac surgical prophylaxis. In two prospective randomized studies, we have compared it with a broad spectrum regimen of an aminoglycoside and flucloxacillin. In the first trial, teicoplanin (400 mg on induction of anaesthesia and 200 mg 24 h later), was compared with tobramycin (80 mg tds for three days) and flucloxacillin (500 mg qds for 5 days) in 314 patients. Teicoplanin prophylaxis resulted in a significantly greater number of sternal wound infections (P less than 0.01), due to Gram-positive bacteria. Furthermore, Gram-negative bacteria were responsible for more respiratory and urinary infections after teicoplanin prophylaxis. In the second trial, comprising 203 patients, the teicoplanin dose regimen was changed to three doses of 400 mg but this did not improve the rates of infection.

Anti-Bacterial Agents↗

PubMed1988

Early and late results of aortic root replacement with antibiotic-sterilized aortic homograft.

Between November 1972 and November 1986, 108 patients aged 5 to 73 years had complete replacement of the aortic root with an aortic homograft into which the coronary arteries were implanted. The main indications were (1) a tunnel type of aortic obstruction involving a hypoplastic ring, (2) a para-aortic annular abscess, (3) prosthetic valve dysfunction, mainly a previous aortic homograft, and (4) aortic stenosis with a small aortic anulus. Eighty-four patients (78%) had previous aortic valve operations. Concomitant cardiac procedures were done in 34 patients (32%). The 30-day mortality rate was 14% (15 patients). The cumulative follow-up period was 180.3 patient-years. The late mortality rate was 6.1% per patient-year (11 patients). The patients were not given anticoagulants postoperatively, but the entire group has been completely free from thromboembolism. The actuarial 5-year survival rate including operative deaths was 72%. The freedom from valve-related death at 5 years after operation is 86% and freedom from reoperation at 5 years is 96%. The use of homografts for replacement of the aortic valve and root in patients with complex lesions affecting these structures has shown encouraging early and late results, with regard to both survival and valve performance.

Actuarial Analysis↗

PubMed1988

Two decades' experience with aortic valve replacement with pulmonary autograft.

Aortic valve replacement with a pulmonary autograft was performed on 241 patients between June 1967 and October 1986 at National Heart Hospital, Guy's Hospital, Middlesex Hospital, Harley Street Clinic, and Italian Hospital in London by one of the authors (D.N.R.). The longest follow-up is 18 years 7 months, and the cumulative total follow-up is 1130 patient-years (pt-yr). The overall 30-day mortality rate is 6.6% (16 patients), with no deaths after 1976, and the late mortality rate is 1.7%/pt-yr (19 patients). The actuarial survival rate is 57.3% +/- 9.6% at 19 years. No anticoagulation has been used and there have been no thromboembolic episodes. The incidence of bacterial endocarditis is 1.2%/pt-yr (14 patients), and its actuarial event-free rate is 74.2% +/- 8.1% at 19 years. Reoperation because of failure of the pulmonary autograft was performed on 36 patients, 27 of whom needed valve replacement. The incidence of pulmonary autograft replacement is 2.5%/pt-yr, and its actuarial event-free rate is 48.5% +/- 13.7% at 19 years. For reconstruction of the right ventricular outflow tract, 186 aortic homografts, 26 pulmonary homografts, 16 autologous fascia lata valved conduits, 7 autologous pericardial conduits with or without a valve, and 6 xenograft valved Dacron conduits were used. Thirty-one patients were reoperated on, mostly because of degeneration of this material. Pulmonary rather than aortic homografts are now favored for reconstruction of the right ventricular outflow tract Because of its satisfactory long-term result without the need for anticoagulation, as well as its safety as an established surgical procedure, this operation can be recommended to a wider range of patients.

Actuarial Analysis↗

PubMed1987

Viability and morphology of aortic and pulmonary homografts. A comparative study.

In view of possible clinical use of the pulmonary homograft for right ventricular outflow tract reconstruction a comparative study with the aortic counterpart was performed. Samples of aortic and pulmonary walls from 10 cadaveric hearts were assessed for viability and morphologic characteristics before and after storage in nutrient-antibiotic solution. The viability, as evaluated by an autoradiographic technique, was similar in both aortic and pulmonary specimens at the time of dissection, after 2 weeks, and after 4 weeks of storage. The histologic examination showed no changes in the structure of the media in all samples up to 4 weeks of storage. The total calcium content per gram of tissue in the pulmonary media was on an average less than half of that in the aortic counterpart. We conclude that the pulmonary homograft is preserved the same as the aortic homograft and, accordingly, it becomes available for clinical application. Moreover, a lesser content of elastic tissue and a lower amount of total calcium may, in all likelihood, make the pulmonary wall less prone to calcification.

Adolescent↗

PubMed1986

Aortico-left ventricular tunnel: late follow-up.

Since 1970, 6 patients have undergone repair of aortico-left ventricular tunnel. Four (67%) had repair in childhood. The technique of closure was by direct suture (5 patients) or patch closure (1 patient). Associated anomalies were seen in 5 patients (83%); absent right coronary ostium (1), commissural fusion (stenosis) (2), valvular regurgitation (3), leaflet defects (2), and healed endocarditis (1). All patients survived operation. At early postoperative review, 67% had mild aortic regurgitation regardless of the technique of surgical repair. Late follow-up revealed that 3 patients (50%) underwent aortic valve replacement (AVR) for progressive aortic regurgitation at a mean of 10 years following initial operation. A review of the literature and our results lead us to conclude that progressive aortic regurgitation is common; it is due to associated valve abnormalities and changes in the valve mechanism secondary to the aortico-left ventricular tunnel. Long-term clinical follow-up is necessary, since 50% of patients will require AVR eventually. Early operation is indicated not only to prevent heart failure but also to prevent progression of damage to the aortic valve.

Adult↗

PubMed1986

The diagnosis of aortic root abscess by cross-sectional echocardiography.

Aortic root abscess is frequently a lethal complication of infective endocarditis. Early diagnosis of this complication is of paramount importance because antibiotic therapy is often ineffective and early surgery is probably the treatment of choice. We have compared the diagnostic accuracy of cross-sectional echocardiography with operative findings in the diagnosis of aortic root abscess. Aortic root abscess was diagnosed in nine of 129 patients with infective endocarditis at the National Heart Hospital between 1983 and 1985. Cross-sectional echocardiography demonstrated the presence and location of the aortic root abscess in eight cases; in the ninth case a small abscess was missed. In two other cases, a large abscess was visualised, but abscesses of between 2 mm and 4 mm were missed; the extent and size of large aortic abscesses tended to be underestimated. Echocardiography should be an integral part of the investigation of patients with aortic valve infective endocarditis.

Abscess↗

PubMed1986

Distal internal mammary artery (IMA) with retrograde flow for coronary artery grafting.

A case in which the right distal internal mammary artery (IMA) was used to graft the posterior descending branch of the right coronary artery is presented. The retrograde blood flow at dissection was 60 ml per minute, no electrocardiographic signs of myocardial ischemia were detected postoperatively. The patient is well and fully active 6 months after surgery.

Coronary Vessels↗

PubMed1985

Fifteen years' experience with the aortic homograft: the conduit of choice for right ventricular outflow tract reconstruction.

Ninety-seven patients with pulmonary atresia underwent right ventricular outflow tract reconstruction using a homograft conduit. There were 46 hospital deaths (47%). Hospital mortality was significantly related to irreversible pulmonary hypertension (p less than 0.001) and thoracotomy for ligation of bronchial collaterals (p less than 0.01). The actuarial survival was 37 +/- 7% at 10 years. Sixteen patients undergoing recatheterization at a mean of 6 years had a mean transconduit gradient of 24 +/- 15 mm Hg. Obstructed conduits (i.e., with a gradient of greater than 50 mm Hg) were replaced in 3 patients, corresponding to 13 +/- 8% at 10 years. In each instance, the obstruction was due to neointimal hyperplasia in the Dacron tube rather than calcification of the homograft valve. The fresh, antibiotic-sterilized aortic homograft is the conduit of choice for right ventricular outflow tract reconstruction. The valve itself appears more resistant to calcification than its xenograft counterpart, and the absence of Dacron removes the problem of fibrinous peel obstructing the conduit. We now construct a tube of autologous pericardium to increase the length of the conduit and avoid complementary thoracotomy for ligation of bronchial collaterals.

Adolescent↗

PubMed1985

Long-term assessment of aortic valve replacement with autologous pulmonary valve.

Two hundred two autologous pulmonary valves were transplanted into the aortic position between 1967 and 1982 at the National Heart Hospital in London. The indication for operation was congenital or acquired aortic valve disease, and the patients were followed for periods from 1 to 4 years. The patients were not anti-coagulated, but the entire series has been completely free from thromboembolism or bleeding. The actuarial prediction of freedom from valve-related deaths was 82 +/- 6% at the end of the fourteenth year after operation; deaths were due to reoperations for technical failure and to infective endocarditis. Event-free survival of the autologous pulmonary valve in the aortic position was 73 +/- 6% after 14 years at risk. Valve failure resulted mainly from technical problems encountered during the early years of surgical experience. There was no macroscopic or histological evidence of calcification in any of the failed valves. The right ventricular outflow was reconstructed with an aortic homograft in the majority of patients; 81 +/- 5% of these homografts demonstrated event-free performance over a 12-year follow-up period. It is concluded that the long-term performance of a pulmonary autograft inserted for aortic valve disease is superior to that of any other valve substitute and that the operation offers an almost ideal means of aortic valve replacement in appropriate patients.

Adolescent↗

PubMed1985

A complicated case of mitral valve disease.

A patient with rheumatic mitral stenosis and previous cerebral embolism had a myocardial infarction during cardiac catheterisation. She later developed severe mitral regurgitation one year after open valvotomy and at valve replacement was found to have a papillary tumour of the mitral valve. Unexplained low cardiac output occurred four days after operation. Postmortem examination showed thrombotic occlusion of the xenograft prosthesis, a complication not previously seen with tissue valves. Both of these rare events were suggested by the patient's clinical course and could have been diagnosed with cross sectional echocardiography.

Bioprosthesis↗