Scandinavian journal of thoracic and cardiovascular surgery. Supplementum最新文献

Following detailed investigation and definition of some of the critical factors relating to the composition and use of cardioplegic protective solutions, we have formulated the St. Thomas' Hospital cardioplegic solution number 2. This cardioplegic solution (NaCl 110.0 mM, NaHCO3 10.0 mM, KCl 16.0 mM, MgCl2 16.0 mM, CaCl2 1.2 mM, pH 7.8) is designed for routine clinical use combining optimal protection with simplicity of formulation and administration/infusion. In order to characterize the efficacy of this modified solution, experiments have been carried out in two species: the isolated rat heart and the in-situ dog heart. In parallel protocols, hearts were subjected to ischemic arrest of up to 4 hours. Multidose (every 40 minutes) cardioplegic infusion of the St. Thomas' solution combined with topical hypothermia extended the tolerable period of ischemia from less than 30 minutes to about 120 minutes in the rat and from less than 60 minutes to more than 180 minutes in the dog. These conclusions were based on the measurement of functional indices together with biochemical, cellular chemical and ultrastructural assessments. The studies confirmed the additive protective properties of hypothermia and chemical cardioplegia and the utility of the rat heart model in the assessment of protective interventions.

Coarctation of the aorta is characterized by a high blood pressure in the upper part of the body and a decreased blood pressure in the lower part. Without surgery it leads to an increased mortality from hypertensive manifestations. However, even after surgery 20--25 per cent of these patients are reported to have a persistent hypertension. Moreover, an increased cardiovascular mortality has been reported. The aim of the present investigations was to study the long-term results after coarctectomy with special emphasis on reactions to hard muscular work and to study some of the possible mechanisms behind this persistent hypertension. Nineteen men aged 16--28 years, operated upon for coarctation of the aorta at an average age of 10 years (range 6--16 years), were investigated 10--11 years after surgery with respect to cardiac and pulmonary function, the state of the vessels and muscle metabolism. Lung function and the intrapulmonary gas exchange were normal, as was the maximal aerobic work capacity. Cardiac output and stroke volume and the arterio-venous oxygen difference were also normal, even during maximal exercise. More than half of the group had a systolic hypertension, both at rest and during exercise, in the upper part of the body, while the diastolic pressure was generally normal. A systolic blood-pressure gradient between the arm and the leg was observed and its was increased during exercise. Corresponding differences in the mean and diastolic pressures were also found during exercise. An increased muscle-lactate concentration in the leg and an increased muscle/blood lactate quotient during exercise indicated a somewhat impaired blood-flow to the leg muscle. The systemic vascular resistance in the right hand during maximal vasodilation was increased much more than the blood-presssure elevation indicated, while the baroreflex sensitivity was adequate. The findings favour early operation for coarctation of the aorta and indicate the necessity of thorough, and probably lifelong, follow-up of these patients. Moreover, blood pressure, either measured at rest or measured during exercise, cannot be used as a measure of the anatomical result after surgery. Key-words: Baroreflex sensitivity, cardiac output, coarctatio aorte, exercise test, hypertension, intra-arterial blood pressure, lung volumes, muscle metabolism, oxygen uptake, peripheral resistance, pulmonary gas exchange.

ECG-tape recording has been utilized for diagnosis of transient attacks of syncope and dizziness both before and during cardiac pacing. The display unit can be utilized for automatic starting of the ECG writer according to markings made by the patient or bradycardia alarm. The method has proved extremely useful and convenient, which is illustrated by cases with different types of arrhythmia and pacemaker failure.

Long-term ECG recording techniques have facilitated the diagnosis in atypical cases of Adams-Stockes syndrome. In the use of ambulatory ECG monitoring, new and mainly technical problems have been arisen. In 200 ECG recordings on cassette tape, 78% was considered sufficient for an accurate diagnosis. More than 50% of the unsuccessful recordings were unreadable due to electrode problems. The use of ambulatory monitoring demands that electrode fixation and placement be handled carefully and that the mechanical and electronic equipment be serviced frequently. Patients with third-degree atrioventricular block and syncopes of fainting spells run a high risk of sudden death. It is therefore not recommended to use ambulatory monitoring techniques on these patients.