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Biomedical subjects

R R Lower

Publications and source records attributed to R R Lower.

At least 55 records · Page 3Linked to original sources
PubMed1982

Circulatory assistance with a cardiac allograft after exclusion of the canine left ventricle.

Cardiogenic shock after myocardial infarction still carries a high mortality despite use of intraaortic counterpulsation and early surgical revascularization. An experimental canine model of left ventricular exclusion and circulation support was developed by closing the mitral valve and by interposing "in series" a cardiac allograft between pulmonary and systemic circulations. This preparation was able to support the recipient circulation after cardiopulmonary bypass in 25 animals. In 16 dogs the graft sustained life for from 1 to 32 days. It is hypothesized that such left ventricular assistance could be used to maintain the life of patients in cardiogenic shock after myocardial infarction. By providing maximal left ventricular decompression and improvement of the native coronary perfusion, this method may reverse the metabolic imbalance responsible for extension of the infarction, thereby salvaging muscle that is in jeopardy but still viable.

Animals↗
PubMed1982

Penetration of moxalactam and cefazolin into atrial appendage after simultaneous intramuscular or intravenous administration.

This study compared the penetration of moxalactam and cefazolin into the human atrial appendage after simultaneous administration of both drugs by two routes. Nineteen adult patients scheduled for coronary vein bypass surgery randomly received 10 mg of moxalactam and cefazolin per kg by either the intramuscular or intravenous (bolus) route on administration of anesthesia. Concentrations of cefazolin in serum were significantly greater than concentrations of moxalactam at all times for both routes of administration. There were no significant differences, however, in the concentration of these drugs in atrial appendages, although concentrations of both agents administered intravenously were significantly greater than of drugs administered intramuscularly. (19.3 +/- 10.3 and 21.0 +/- 11.0 micrograms intravenously versus 8.3 +/- 3.6 and 10.1 +/- 3.2 micrograms/g intramuscularly for moxalactam and cefazolin, respectively).

Aged↗
PubMed1982

Prevalence and significance of arrhythmias in long-term survivors of cardiac transplantation.

The prevalence and significance of arrhythmias after cardiac transplantation were evaluated in the absence of acute rejection in 13 long-term survivors (greater than 3 months). ECGs were obtained daily for the first 70 days 8- and 24-hour ambulatory electrocardiographic monitoring was performed 3 months after the transplantation and every 6 months thereafter. Junctional rhythm occurred during the early transplant period (less than 70 days) in nine of 13 patients. Complex premature ventricular depolarizations (Lown grade III or higher) were present in the late transplant period (greater than 70 days) in all five patients in whom severe coronary artery disease was found in the donor heart at postmortem, compared with two of the eight remaining patients (six survivors and two patients who died but did not have coronary artery disease at postmortem) (p less than 0.05). The high prevalence of junctional rhythm in the early transplant period appeared to be due to sympathetic denervation and reversible surgical damage to and ischemia of the sinus node region of the donor heart. Routine ambulatory electrocardiographic monitoring detected complex premature ventricular depolarizations, which were a sensitive marker for the subsequent mortality related to accelerated atherosclerosis of chronic rejection in the donor heart.

Adult↗
PubMed1981

Left ventricular mass by M-mode echocardiography in cardiac transplant patients with acute rejection.

Serial determination of left ventricular mass, right ventricular and left atrial size, fractional shortening and left ventricular systolic time intervals were made from M-mode echocardiograms in 13 long-term survivors with cardiac allografts These measurements were correlated with presence or absence of acute rejection as determined by myocardial biopsy. Left ventricular mass increased significantly, from a baseline of 129.8 +/- 11.8 (mean +/- SEM) to 310.5 +/- 13.0 g during 12 episodes of rejection. In contrast during eight episodes without rejection, the left ventricular mass did not increase significantly (baseline 175.2 +/- 11.8 to 211.9 +/- 25.6 g). There was no relationship between changes in right ventricular and left atrial size, fractional shortening or systolic time intervals and presence or absence of rejection of myocardial biopsy. An increase in left ventricular mass by M-mode echocardiography offers a reliable noninvasive method for detection of acute rejection of a cardiac allograft.

Echocardiography↗
PubMed1981

Successful orthotopic canine heart transplantation after 24 hours of in vitro preservation.

A protocol was developed to provide continuous, hypothermic, low-pressure perfusion for 24 hours' preservation of the isolated canine heart prior to orthotopic transplantation. Donor cardiectomy included coronary vasodilatation with diltiazem, potassium arrest, and rapid cooling of the heart. The graft was perfused at a pressure of 18 to 22 cm H2O and at an average flow of 0.743 cc/min/gm of tissue. The septal temperature was 5 degrees to 7 degrees C and perfusate pH was 7.25 to 7.4. Two groups of mongrel dogs were studied after orthotopic transplantation: Group I (n = 15) received hearts perfused for 24 hours. Group II (n = 9) received hearts removed by the same cardiectomy technique, but transplanted immediately. All grafts were able to support the recipient circulation after cardiopulmonary bypass. These was no significant difference in survival or in graft function when hemodynamic studies were done in five animals of each group, between 5 and 10 days after operation. We conclude that a reliable and reproducible method of 24 hours' in vitro perfusion of the canine heart has been obtained and should be applicable in clinical cardiac transplantation when prolonged periods of preservation are required.

Animals↗
PubMed1980

Blalock-Taussig shunt to a pulmonary vein: an unusual surgical complication.

Thickening of the wall of pulmonary veins in cyanotic congenital heart disease and the presence of hilar vessel anatomic variants may mislead a surgeon into incorrectly anastomosing the subclavian artery to the pulmonary vein when performing a Blalock-Taussig shunt. Emergency selective angiography is the study of choice for the identification of this operative complication.

Adolescent↗
PubMed1980

Cardiac transplantation at the Medical College of Virginia.

The world's second largest experience in orthotopic cardiac transplantation has been achieved at the Medical College of Virginia, where significant progress has been made in the refinement of surgical technique, use of immunosuppression, and treatment of post-transplant complications. The procedure may now be regarded with cautious optimism, according to the authors, who document the MCV experience and describe the criteria for heart transplant candidates.

Graft Survival↗
PubMed1980

Cardiac transplantation--1980: The Medical College of Virginia program.

Within the last three years, advances in the fields of cardiac surgery and immunology have established the value of cardiac transplantation for patients with irreversible myopathic disease. Long-distance donor procurement has increased the availability of the donor pool and made possible a more critical selection of donor hearts. The development of antithymocyte globulin and the concept of individual immune monitoring has decreased the incidence of acute rejection and the dosage of prednisone and azathioprine necessary to achieve optimal graft protection. These advances are reflected in the survival statistics. Since 1977, the three-month mortality rate has decreased to 40%, as compared to 77% from 1968 to 1976. Ptatients who are discharged from the hospital are currently demonstrating an 88% one-year survival rate and are functional class I-II status. We conclude that in properly selected patients, cardiac transplantation is a viable option for end-stage cardiomyopathic disease.

Antilymphocyte Serum↗
PubMed1979

Improved immunosuppression for cardiac transplantation: immune monitoring and individualized modulation of recipient immunity by in vitro testing.

These studies demonstrate that immune monitoring and individualized modulation of recipient immune reactivity using a quality-controlled preparation of rabbit antithymocyte globulin can improve results of cardiac transplantation. The most valuable assay in individualizing drug doses was the serial measurement of T-cell levels using a complete lymphocyte profile technique and monitoring with phytohemagglutinin to rule out false low T-cell levels. Using this system, the incidence and severity of early rejections were markedly reduced and no grafts were lost to rejection in the first month. The recent first-year graft survival has been about 60%, an improvement largely related to a reduction in early rejection and infection. This technique of immunosuppression appears quite promising for improving the results of future cardiac transplantations.

Antilymphocyte Serum↗