A new type of pump, the differential displacement pump, has recently been developed. The new pump and a conventional pneumatic displacement pump were evaluated with respect to pump flow, filling pressures, stroke frequency, and inflow pattern under equivalent test conditions. The pumps were connected via inlet and outlet cannulas to a Donovan hydraulic circulation analogue. The differential displacement pump showed a high sensitivity to filling pressure in the range of 2.3-9.6 L/min/mmHg, and a high efficiency as long as the stroke volume was submaximal. The inflow was continuous and pulsatile with a maximal forward flow velocity during systole as long as the maximal stroke volume was not employed. In contrast, the conventional displacement pump showed low sensitivity to filling pressures, a discontinuous inflow, with a maximal inlet cannula forward flow during diastole and a substantial flow reversal during systole. These results indicate that the differential displacement pump is a better concept with respect to sensitivity to venous return, and that it provides an inflow pattern and regulation of pump flow similar to that of the biologic heart.

Equipment Design↗

PubMedDate not supplied

Summary of the world experience with clinical use of total artificial hearts as heart support devices.

A review of the world experience with the implantation of total artificial hearts has been carried out. Thirteen centers throughout the world have implanted 27 total artificial hearts in 26 patients. Eight different types of total artificial hearts have been employed. As of June 1, 1986, five of these individuals have had implants for permanent support. Of the other twenty-one patients, three patients died while on a total artificial heart, seven patients died following transplantation, two patients are waiting for transplant, and nine patients have successfully been transplanted and are presently alive. Various clinical preoperative and postoperative parameters are analyzed in this investigation.

Adult↗

PubMedDate not supplied

Surgical positioning of the Jarvik-7 artificial heart.

The Jarvik-7 total artificial heart has been implanted in 18 patients at the time of this writing. Eleven patients received the 100 ml heart, and the remaining seven were treated with the 70 ml device. To date, five patients have been implanted for permanent use with an average survival in excess of 9 months, and the longest survival is more than 1 1/2 years following implantation of the heart. Complications related to positioning were a contributing factor in the death of one patient. Thirteen patients have received the Jarvik-7 heart as a bridge to transplant. Three died before transplant, and the remaining ten have been transplanted. To date, all are alive, several are home and in excellent condition, and several are still hospitalized but are expected to be released shortly. Three patients have experienced serious complications after transplantation. One patient rejected her heart transplant, was reimplanted with the artificial heart, and now has been sustained for more than 3 months. At this time she is in good condition awaiting a second donor. Selection of the appropriate size Jarvik-7 artificial heart for the individual patient can best be made based on measurements of thoracic dimensions obtained from a computed tomography scan and calculation of body surface area. The appropriate medial or lateral positioning can be determined and decisions concerning the lengths of the grafts and cuffs, excision or nonexcision of the left pericardium, and air drive line position can be made. The Jarvik-7 heart can be successfully used in patients from 50 kg. However, at the lower size limit in patients from approximately 50 to 65 kg, the risk of fit complications is the greatest and availability of an even smaller model heart would be desirable.

Adult↗

PubMedDate not supplied

Complete replacement of the ascending aorta and the aortic valve with coronary reimplantation.

In 6 patients with cystic medial necrosis of the ascending aorta and the aortic root complete elective replacement of these structures with coronary reimplantation was performed. Two patients died from postoperative left ventricular failure, 4 patients survived and were hemodynamically unaffected at follow-up. Also the heart size in these patients decreased postoperatively. Survival seemed mainly related to the degree of preoperative cardiac failure and cardiomegaly.

Adolescent↗

PubMedDate not supplied

Comparison of intraoperative flow measurements and haemodynamic findings at follow-up in patients with different aortic disc valve prostheses.

Intraoperative as well as postoperative assessment of effective orifice area, determined by relating flow through a prosthetic heart valve to the pressure gradient measured across the valve, provides a data base for comparison of different types of cardiac prostheses. As a measure of valve performance, we have used the derivation of both the effective area according to the Aaslid formula measured intraoperatively and to the Gorlin formula measured at a re-catheterization study. We also established the parameter 'effective index area', Ia or Ii. Ia is defined as the ratio between the effective orifice area and the annulus orifice area, and Ii as the ratio between the effective orifice area and the internal orifice area of the valve housing. The patients included in the study had either Lillehei-Kaster, Björk-Shiley or Hall-Kaster aortic valve prostheses inserted. In most of the Lillehei-Kaster prostheses, Ia varied around 0.27 and Ii around 0.56, while the corresponding values in the Björk-Shiley prostheses were 0.35 and 0.56, increasing to around 0.50 and 0.75 respectively in the Hall-Kaster prostheses.

Adult↗

PubMedDate not supplied

The Hall-Kaster disc valve prosthesis: clinical and hemodynamic observations in patients undergoing aortic valve replacement.

In a series of 113 patients receiving Hall-Kaster aortic valve prostheses intraoperative- and postoperative hemodynamic studies revealed favourable utilization of the valve orifice for transvalvar forward flow. Angiography demonstrated optimal disc opening and minor valvar regurgitation. A significant clinical improvement and improvement of left ventricular function were observed postoperatively.

Aged↗