Steunharten, tijdelijk of blijvend? / Jaap R. Lahpor ; Beeld en getal / Lex A. van Herwerden

Steunharten, tijdelijk of blijvend? In 1969 vond er in Houston, Texas een ruzie plaats tussen 2 gerenommeerde hartchirurgen, een ruzie die zou ontaarden in een historische vete. De oorzaak was de eerste klinische implantatie van een kunsthart als overbrugging naar een harttransplantatie. De betrokken chirurgen waren Dr. Denton Cooley en Dr. Michael DeBakey. Eerstgenoemde had volgens Dr. DeBakey het prototype van een kunsthart, dat hij samen met Dr. Liotta had ontwikkeld, zonder overleg en zonder toestemming uit het laboratorium gehaald en geïmplanteerd bij een 47-jarige hartpatiënt. Hoewel de implantatie succesvol kon worden genoemd, overleed de patiënt 65 uur later tijdens een harttransplantatie. Het heeft bijna 40 jaar geduurd, voordat beide heren deze vete hebben bijgelegd. Zij hadden toen de respectabele leeftijd van 87 en 99 jaar. De hele geschiedenis van de toepassing van implanteerbare steunharten in Utrecht, die ik hierna uit de doeken zal trachten te doen, heeft in het licht gestaan van deze historische gebeurtenis. Dat je ook zonder een ruzie je naam kunt verbinden aan de ontwikkeling van kunstorganen heeft onze beroemde landgenoot Dr. Willem Kolff bewezen, de uitvinder van de kunstnier. Hij stond ook aan de wieg van het eerste succesvolle pneumatische kunsthart, de Jarvik-7. Beeld en getal De kleine jongen loopt snel voor ons uit om te zien wat er achter de berg is en ziet dat daarachter een volgende berg is, even raadselachtig als de vorige. Verwondering en nieuwsgierigheid. Ook voor wetenschapsbeoefening is dit de drijvende kracht. Onderzoek en vernieuwing zijn als een bergwandeling: het is aangenaam, de vergezichten adembenemend en af en toe beleef je de schok van iets geheel nieuws. Vergeleken met de wereld van het kind is de schaal van het spel groter. De mogelijkheid om verwondering en nieuwsgierigheid in het dagelijks werk te integreren, is de unieke dimensie van het academisch ziekenhuis

Characterization of patients with continuous flow left ventricular assist devices

No abstract

Characterization of patients with continuous flow left ventricular assist devices

No abstract

Simulation of changes in myocardial tissue properties during left ventricular assistance with a rotary blood pump

We considered a mathematical model to investigate changes in geometric and hemodynamic indices of left ventricular function in response to changes in myofiber contractility and myocardial tissue stiffness during rotary blood pump support. Left ventricular assistance with a rotary blood pump was simulated based on a previously published biventricular model of the assisted heart and circulation. The ventricles in this model were based on the one-fiber model that relates ventricular function to myofiber contractility and myocardial tissue stiffness. The simulations showed that indices of ventricular geometry, left ventricular shortening fraction, and ejection fraction had the same response to variations in myofiber contractility and myocardial tissue stiffness. Hemodynamic measures showed an inverse relation compared with geometric measures. Particularly, pulse pressure and arterial dP/dtmax increased when myofiber contractility increased, whereas increasing myocardial tissue stiffness decreased these measures. Similarly, the lowest pump speed at which the aortic valve remained closed increased when myofiber contractility increased and decreased when myocardial tissue stiffness increased. Therefore, simultaneous monitoring of hemodynamic parameters and ventricular geometry indirectly reflects the status of the myocardial tissue. The appropriateness of this strategy will be evaluated in the future, based on in vivo studies

Simulation of changes in myocardial tissue properties during left ventricular assistance with a rotary blood pump

We considered a mathematical model to investigate changes in geometric and hemodynamic indices of left ventricular function in response to changes in myofiber contractility and myocardial tissue stiffness during rotary blood pump support. Left ventricular assistance with a rotary blood pump was simulated based on a previously published biventricular model of the assisted heart and circulation. The ventricles in this model were based on the one-fiber model that relates ventricular function to myofiber contractility and myocardial tissue stiffness. The simulations showed that indices of ventricular geometry, left ventricular shortening fraction, and ejection fraction had the same response to variations in myofiber contractility and myocardial tissue stiffness. Hemodynamic measures showed an inverse relation compared with geometric measures. Particularly, pulse pressure and arterial dP/dtmax increased when myofiber contractility increased, whereas increasing myocardial tissue stiffness decreased these measures. Similarly, the lowest pump speed at which the aortic valve remained closed increased when myofiber contractility increased and decreased when myocardial tissue stiffness increased. Therefore, simultaneous monitoring of hemodynamic parameters and ventricular geometry indirectly reflects the status of the myocardial tissue. The appropriateness of this strategy will be evaluated in the future, based on in vivo studies

Pump flow estimation from pressure head and power uptake for the HeartAssist5, HeartMate II and HeartWare VADs

The use of long-term mechanical circulatory support (MCS) for heart failure by means of implanted continuous-flow left ventricular assist devices (cf-LVADs) will increase, either to enable recovery or to provide a destination therapy. The effectiveness and user-friendliness of MCS will depend on the development of near-physiologic control strategies for which accurate estimation of pump flow is essential. To provide means for the assessment of pump flow, this study presents pump models, estimating pump flow (Qlvad) from pump speed (n) and pressure difference across the LVAD ([DELTA]plvad) or power uptake (P). The models are evaluated for the axial-flow LVADs HeartAssist5 (HA5) and HeartMate II (HMII), and for a centrifugal pump, the HeartWare (HW). For all three pumps, models estimating Qlvad from [DELTA]plvad only is capable of describing pump behavior under static conditions. For the axial pumps, flow estimation from power uptake alone was not accurate. When assuming an increase in pump flow with increasing power uptake, low pump flows are overestimated in these pumps. Only for the HW, pump flow increased linearly with power uptake, resulting in a power-based pump model that estimates static pump flow accurately. The addition of pressure head measurements improved accuracy in the axial cf-LVAD estimation models

Exercise hemodynamics during extended continuous flow left ventricular assist device support : the response of systemic cardiovascular parameters and pump performance

Patients on continuous flow left ventricular assist devices (cf-LVADs) are able to return to an active lifestyle and perform all sorts of physical activities. This study aims to evaluate exercise hemodynamics in patients with a HeartMate II cf-LVAD (HM II). Thirty (30) patients underwent a bicycle exercise test. Along with exercise capacity, systemic cardiovascular responses and pump performance were evaluated at 6 and 12 months after HM II implantation. From rest to maximum exercise, heart rate increased from 87 +/- 14 to 140 +/- 32 beats/minute (bpm) (

Heart transplantation in the Netherlands: quo vadis?

Heart transplantation is limited by the lack of donor organs. Twenty years after the start of the Dutch transplant programmes in Rotterdam and Utrecht the situation has even worsened, despite efforts to increase the donor pool. The Dutch situation seems to be worse than in other surrounding countries, and several factors that may influence donor organ availability and organ utilisation are discussed. The indications and contraindications for heart transplantation are presented, which are rather restrictive in order to select optimal recipients for the scarce donor hearts. Detailed data on donor hearts, rejected for transplantation, are shown to give some insight into the difficult process of dealing with marginal donor organs. It is concluded that with the current low numbers of acceptable quality donor hearts, there is no lack of capacity in the two transplanting centres nor is the waiting list limiting the number of transplants. The influence of our current legal system on organ donation, which requires (prior) permission from donor and relatives, is probably limited. The most important determinants of donor organ availability are: 1. The potential donor pool, consisting of brain dead victims of (traffic) accidents and CVAs and 2. Lack of consent to a request for donation. The potential donor pool is remarkably small in the Netherlands, due to relatively low numbers of (traffic) accidents, with an almost equal number of CVA-related brain dead patients compared with neighbouring countries. Lack of consent can only be pushed back by improved public awareness of the importance of donation and improved skills of professionals in asking permission in case there is no previous consent