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Biomedical subjects

J M Neutze

Publications and source records attributed to J M Neutze.

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

Rest and exercise hemodynamics of 20 to 23 mm allograft, Medtronic Intact (porcine), and St. Jude Medical valves in the aortic position.

Doppler echocardiography was used to measure gradients and valve areas at rest and after supine bicycle exercise in 35 patients with valve replacements 20 to 23 mm in size. Thirteen patients with a St. Jude Medical valve (St. Jude Medical, Inc., St. Paul, Minn.) were matched to 13 patients with an allograft valve, and seven patients with a Medtronic Intact (porcine) valve (Medtronic, Inc., Minneapolis, Minn.) to seven patients with an allograft valve. Patients were matched for age, sex, valve size, body surface area, and left ventricular systolic function. There was no statistically significant difference between the matched groups for body surface areas, resting cardiac output, exercise heart rate, or workload achieved. Mean pressure gradient was higher for St. Jude Medical than for allograft groups, both at rest (11.8 +/- 6.67 mm Hg for St. Jude Medical versus 6.67 +/- 2.98 mm Hg for allografts) and after exercise (16.4 +/- 8.47 mm Hg versus 9.7 +/- 3.94 mm Hg), but the differences were of borderline significance (p = 0.016 and 0.027, respectively). Valve area at rest was similar for both devices (1.4 +/- 0.45 cm2 for St. Jude Medical versus 1.8 +/- 0.56 cm2 for allograft; p greater than 0.1). There were highly significant differences between patients with Intact and those with allograft valves for resting mean pressure gradient (19.3 +/- 4.23 mm Hg for Intact versus 5.9 +/- 3.68 mm Hg for allograft; p less than 0.001) and for exercise mean pressure gradient (27.8 +/- 8.63 mm Hg versus 8.1 +/- 8.43 mm Hg; p less than 0.001). The differences between the valve areas at rest also were significant (1.1 +/- 0.12 cm2 versus 2.2 +/- 0.62 cm2; p less than 0.01). It is concluded that when a tissue valve is indicated in patients with a small aortic root, the freehand allograft aortic valve is an ideal device from the hemodynamic perspective and is superior to the Intact valve. It is also probably superior in this respect to the St. Jude Medical valve, although the analysis may be biased slightly in favor of the allograft valve.

Aged↗
PubMed1989

Assessment and follow-up of patients with ventricular septal defect and elevated pulmonary vascular resistance.

Cardiac catheterization was undertaken in 87 patients (for a total of 89 studies) with ventricular septal defects, including 58 patients with moderate or severe elevation of pulmonary arteriolar resistance. When resting resistance was less than or equal to 7.9 U . m2, it always decreased with isoproterenol and no postoperative problems were experienced with pulmonary vascular obstructive disease. In 36 patients resting resistance measured greater than or equal to 8 U . m2. In 17 of these patients it decreased to less than 7 U . m2 with isoproterenol. Fifteen patients were operated on and postoperative problems with pulmonary vascular disease were experienced only in the single patient whose repair broke down. Surgery was undertaken in 4 of 19 patients in whom resistance did not decrease to less than 7 U . m2 with isoproterenol and advanced pulmonary vascular disease was evident in the 3 patients with follow-up observation. Correlation between measured resistance and other hemodynamic parameters was only fair. A pulmonary to systemic resistance ratio greater than or equal to 0.75 always indicated high absolute resistance but resistance ratios less than 0.75 were found quite frequently in the group with limited response to isoproterenol. These data argue that a reliable estimate of resistance, less than 7 U . m2, with a vasodilator predicts a good postoperative response regardless of measurements at rest or other hemodynamic parameters. Although observations on postoperative progress of patients with resistance greater than 7 U . m2 with a vasodilator are limited, a good postoperative course is unlikely unless resistance can be lowered to a level close to 7 U . m2.

Adult↗
PubMed1989

Early follow-up of patients with the Medtronic Intact porcine valve. A new cardiac bioprosthesis.

A new-generation porcine valve fixed in glutaraldehyde at zero pressure and mounted on an acetal copolymer flexible stent was inserted in 97 patients between August 1983 and October 1986. The mean age of the patients was 51 years (range 10 to 76) and eight were under the age of 20 years. There were 57 mitral, 33 aortic, and 10 tricuspid valve replacements. Concomitant coronary artery bypass grafting was performed in 9% of patients, 40% underwent multiple valve operations, and in 40% the procedure was a reoperation. Mean follow-up was 26 months (range 12 to 49) and was 99% complete. There were no examples of primary tissue failure, and only to reoperations have been undertaken for infective endocarditis alone. The early mortality rate was 8.2% and the late mortality rate, 12.1%. Four late deaths were valve related (two caused by infective endocarditis and two by embolism). The actuarial 3-year survival rate was 70%, freedom from infective endocarditis 879%, freedom from embolism 87%, freedom from reoperation 90%, and freedom from valve-related complications 77%. All but three surviving patients were in New York Heart Association class I or II. Doppler echocardiography, performed in 62 of 76 survivors, showed thin and mobile leaflets in all patients and trivial or mild regurgitation in four (6%). The mean gradient across the Medtronic Intact valves (Medtronic Blood Systems Inc., Minneapolis, Minn.) in the aortic position was 17 +/- 5.2 mm Hg, in the mitral position 3.8 +/- 1.33 mm Hg, and in the tricuspid position 4.1 +/- 1.14 mm Hg. We conclude that early results with the Intact valve are encouraging.

Adolescent↗
PubMed1987

What contribution has cardiac surgery made to the decline in mortality from coronary heart disease?

The number of deaths from coronary artery disease is declining in New Zealand as in some other Western countries. It has been estimated that in 1981 in the Auckland metropolitan area there were 126 fewer deaths than would have been expected from the data in 1974. The contribution made by cardiac surgery to this decline was assessed from the known numbers of patients who were operated on, from their survival rate, and from the predicted mortality of the surgical cohort had they not undergone operation. Such mortality was predicted from past studies of patients with similar symptoms, exercise data, studies of unstable angina, and the coronary artery surgical study registry. From this method it was estimated that coronary surgery accounted for 26% to 42% of the reduction in coronary deaths. Two previous studies estimated, from calculations based on the European study of patients with modest symptoms, that the contribution of cardiac surgery was much lower. Extrapolating data from one subset of patients to a second subset with quite different characteristics is a conceptual fallacy.

Angina Pectoris↗
PubMed1987

Inheritance of hypertrophic cardiomyopathy: a cross sectional and M mode echocardiographic study of 50 families.

To determine the mode of inheritance of hypertrophic cardiomyopathy 193 first degree relatives (parents, siblings, and offspring) of 50 patients with hypertrophic cardiomyopathy were assessed by clinical examination, electrocardiography, M mode and cross sectional echocardiography, and necropsy when available. Thirty nine (20%) first degree relatives had hypertrophic cardiomyopathy--37% of parents, 25% of siblings, and 8% of offspring. Eight (23%) of 35 affected relatives diagnosed by echocardiography had normal clinical and electrocardiographic findings. In the total study group 43% of the male population and 30% of the female population were affected. This difference is statistically significant. In 28/50 families there was familial occurrence of hypertrophic cardiomyopathy. Familial occurrence was demonstrated in 17 of 18 families in which five or more family members were assessed. In 15 families the pattern of inheritance was consistent with an autosomal dominant trait; in the other 13 the affected members were identified in a single generation and the pattern of inheritance could not be determined.

Adolescent↗
PubMed1986

A familial syndrome of cardiac myxomas, myxoid neurofibromata, cutaneous pigmented lesions, and endocrine abnormalities.

A family syndrome of cardiac myxomas, myxoid neurofibromata, cutaneous pigmented lesions, and endocrine abnormalities is described. Three cases from a family of four are presented. All had cutaneous pigmented lesions. The mother had left and right atrial myxomata, her daughter a left ventricular myxoma, subcutaneous myxoid neurofibromata, and mammary fibroadenosis, and her son has no evidence of cardiac myxoma. Elevated circulating levels of insulin-like growth factors in the one family member tested raises the possibility of abnormal stimulation of somatic growth and may be linked to development of soft tissue neoplasms in these patients.

Adolescent↗
PubMed1985

Prosthetic repair of coarctation of the aorta with particular reference to Dacron onlay patch grafts and late aneurysm formation.

Prosthetic material was used in the repair of coarctation of the aorta in 72 patients followed for 8 months to 24 years after operation. False aneurysms occurred late postoperatively in 1 of 17 instances when a tube graft was used to replace the resected aorta and in 1 of 2 patients when the graft bypassed the obstructed area. A Dacron onlay patch graft (DOPG) was used in 52 patients as the primary method of repair, to revise a previous repair or as an adjunct to another procedure at the time of initial operation. True or false late aneurysm occurred between 6 and 18 years postoperatively in 5 of the 38 patients in whom a DOPG was used for primary repair of the coarctation or to revise an earlier repair, an actuarial incidence of 38% at 14 years. Diagnosis of aneurysm formation late postoperatively depends on awareness of this complication and careful assessment of lateral as well as posteroanterior chest radiographs. DOPG should be avoided whenever possible.

Actuarial Analysis↗
PubMed1985

The effects of prostacyclin (PGI2) on haematological and haemodynamic parameters, and lung histology in puppies undergoing cardiopulmonary bypass surgery with profound hypothermia.

Puppies 6-12 kg underwent cardiopulmonary bypass with profound hypothermia. Thirteen animals received 200 ng kg-1 min-1 of PGI2 during bypass whilst 11 control animals received equivalent volumes of glycine buffer (placebo) over a similar period. Results indicated preservation of platelets, leukocytes and fibrinogen levels, together with shortened activated partial thromboplastin times and fewer fibrinogen degradation products post-bypass in PGI2-treated animals. There was an initial fall in blood pressure and systemic vascular resistance in PGI2 treated animals, but pulmonary pressures and resistances, cardiac outputs, and heart rates showed no significant differences from controls. Higher and more satisfactory end of bypass and post-bypass blood pressure levels, together with a lesser fall-off in mean total pulmonary compliance, and shortened bypass times were achieved in treated animals. PGI2 appeared to afford some protection against lung damage as observed by histological studies. All beneficial effects appeared to be significantly greater amongst smaller animals. The results indicate possible benefits from the use of PGI2 in infant open heart surgery.

Animals↗
PubMed1985

Arrhythmia prophylaxis after aorta-coronary bypass. The effect of minidose propranolol.

After aorta-coronary bypass grafting, 164 consecutive patients were randomized to receive propranolol 5 mg every 6 hours orally (n = 82) or to serve as control subjects (n = 82). All patients were receiving beta blockers preoperatively. There were no significant differences between the two groups. The incidence of sustained supraventricular (nonsinus) tachyarrhythmias was 23% in the control group and 9.8% in the treated group (p = 0.02). The incidence of ventricular arrhythmias was 15% in the control group and 2.4% in the treated group (p = 0.005). The overall difference in clinically important arrhythmias was 38% in the control group and 12.2% in the treated group (p = 0.0002). We conclude that low-dose oral propranolol in patients who were receiving beta blockers preoperatively is effective in reducing the incidence of clinically important arrhythmias occurring after aorta-coronary bypass grafting.

Aged↗