Surgical alternatives in the treatment of heart failure

Telemetric left ventricular monitoring using wireless telemetry in the rabbit model

Background

Heart failure is a critical condition that affects many people and often results from left ventricular dysfunction. Numerous studies investigating this condition have been performed using various model systems. To do so, investigators must be able to accurately measure myocardial performance in order to determine the degree of left ventricular function. In this model development study, we employ a wireless telemetry system purchased from Data Sciences International to continuously assess left ventricular function in the rabbit model.

Findings

We surgically implanted pressure-sensitive catheters fitted to wireless radio-transmitters into the left ventricle of Dutch-belted rabbits. Following recovery of the animals, we continuously recorded indices of cardiac contractility and ventricular relaxation at baseline for a given time period. The telemetry system allowed us to continuously record baseline left ventricular parameters for the entire recording period. During this time, the animals were unrestrained and fully conscious. The values we recorded are similar to those obtained using other reported methods.

Conclusions

The wireless telemetry system can continuously measure left ventricular pressure, cardiac contractility, and cardiac relaxation in the rabbit model. These results, which were obtained just as baseline levels, substantiate the need for further validation in this model system of left ventricular assessment.

Anticoagulant monitoring in ventricular assist device patients: a feasibility study

We conducted a feasibility study to monitor coagulation using a point-of-care device (proTime micro coagulation system) in ventricular assist device (VAD) patients. The aim of the study was to compare International Normalized Ratio (INR) readings using a standard laboratory method and proTime micro coagulation device in order to confirm a correlation between these two methods. The nurse's feedback about anticoagulation monitoring using portable anticoagulant monitoring devices in the hospital was also assessed. Four patients admitted in the cardiac surgery unit at University of Maryland, Baltimore were enrolled between 25 November 2006 and 20 December [corrected] 2006. These patients had given consent to undergo both venous and finger-stick blood samplings to monitor their anticoagulant levels. Six hospital nurses participated in the study. Forty-one INR readings were compared using both methods. Correlation coefficients determined association between INR readings using two methods. All the patients were males and were hypertensive. Significant positive association was seen in the INR readings using two methods (r=0.96; P<0.0001). Four of the six nurses believed patients would be significantly safer if INR is monitored by VAD patients in their homes. Further research needs to be done to determine the impact of home INR monitoring and long-term health in these patients.