Delivery pressure of the cardioplegic solution influences myocardial protection.

To investigate whether cardioplegic solution (CS) delivery pressure influences myocardial protection, intermittent infusions of CS at different pressures were used in an isolated Langendorff rat heart preparation. In group 1 the hearts were kept arrested for 210 min at 12 degrees C with intermittent infusions of 5 ml CS every 20 min at 30 cm H2O (22 mmHg) pressure, in group 2 the same volume of CS was infused at 100 cm H2O (73.5 mmHg) pressure, in group 3 at 145 cm H2O (106.5 mmHg) pressure and in group 4 at 238 cm H2O (175 mmHg) pressure. There was a significantly higher coronary resistance in groups 1 and 4 (7.3 +/- 0.2 RU and 6.9 +/- 0.2 RU) than in groups 2 and 3 (4.2 +/- 0.2 RU and 4.2 +/- 0.2 RU) (P < 0.05) during the ischemic period. There were no significant differences between group 2 and 3 in the reperfusion period. Groups 2 and 3 showed higher coronary flow and left ventricle developed pressure than group 1 and 4. Hearts from group 1 and 4 had lower adenosine triphosphate (7.88 +/- 0.44 mumol.g-1, 5.56 +/- 0.56 mumol.g-1) (P < 0.05) and creatine phosphate (24.66 +/- 0.47 mumol.g-1, 15.34 +/- 0.94 mumol.g-1) (P < 0.05) content at the end of the reperfusion period than group 2 (10.56 +/- 0.41 mumol.g-1, 30.06 +/- 0.38 mumol.g-1) and group 3 (14.13 +/- 0.69 mumol.g-1, 35.25 +/- 0.78 mumol.g-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary autoregulation protects against harmful effects of commonly used cardioplegia delivery pressure.

OBJECTIVE: Hearts or parts of hearts are often ischemic prior to infusion of the cardioplegic solution and have a more or less dilated coronary bed. We made an investigation whether coronary dilation just prior to induction of cardiac arrest by aortic clamping and infusion of crystalloid cardioplegic solution would influence cardioprotection. METHODS: Isolated buffer-perfused rat hearts (100 cm H2O pressure (= 73.5 mmHg), 37 degrees C) were used. After a stabilization period the perfusion of 8 rats (group 1) was stopped and the hearts arrested with 5 ml CS (100 cm H2O, 12 degrees C). Equal amounts of cardioplegic solution were then delivered every 20 minutes for the entire 3 1/2 hour hypothermic ischemic period. Following ischemia the hearts were reperfused for 60 minutes. In group 2 (n = 8) 1 ml 10(-2) mmol Papaverine was given into the aortic root just prior to the first cardioplegic solution infusion in order to induce coronary vasodilation. The procedure was identical in the two groups during ischemia and reperfusion. RESULTS: During the ischemic period coronary resistance increased in group 2. During reperfusion group 2 had lower coronary flow (P = 0.001), left ventricle developed pressure (P = 0.002) and a higher creatine kinase release (P = 0.003) than group 1 hearts. Group 2 also had a lower adenosine-triphosphate (6.51 +/- 0.40 mumol.g-1 and 14.03 +/- 0.59 mumol.g-1, respectively, P = 0.011), creatine phosphate (24.70 +/- 1.02 mumol.g-1 and 36.50 +/- 1.31 mumol.g-1, respectively, P = 0.020) and a larger fall in dry/wet-weight ratio (1.7 +/- 0.4 and 0.8 +/- 0.5, respectively, P = 0.043). CONCLUSIONS: Vasodilation (i.e. ischemia) just prior to infusion of crystalloid cardioplegic solution may impair myocardial protection even when the cardioplegic solution is delivered at a relatively low and presumably safe pressure.

Cardiac dysfunction and inefficiency after substrate-enriched warm blood cardioplegia.

OBJECTIVE: The study assessed the outcome after prolonged warm continuous antegrade blood cardioplegia (WCBC) with substrate enrichment, in terms of mechanical performance and mechanoenergetic efficiency. METHODS: WCBC was given for 3 h to three groups of pigs on cardiopulmonary bypass; WCBC alone (n=7), WCBC+glucose and insulin (+GIK, n=7) and WCBC+L-glutamine (+GLN, n=7). Cardiac systolic and diastolic function, pressure-volume area (PVA) and myocardial oxygen consumption (MVO(2)) were assessed before, and twice after WCBC using pressure-conductance catheter, coronary flow-probes and O(2)-content difference. RESULTS: In the WCBC, +GIK and +GLN groups respectively, the following parameters decreased after WCBC compared to baseline: left ventricular developed pressure by 26, 19 and 25% (P<0.001); dP/dt(max) by 36, 37 and 34% (P<0.001); preload recruitable stroke work by 35, 41 and 28% (P<0.001); mechanoenergetic efficiency (PVA/MVO(2)) by 44, 41 and 22% (P<0.001). End-diastolic stiffness increased early after WCBC in the WCBC and +GLN groups, while it was unchanged in the +GIK group (P=0.032). CONCLUSION: Despite continuous aerobic conditions and additional substrates, post-WCBC cardiac contractile function and mechanoenergetic efficiency was severely depressed. The results demonstrate the hazards of sustained normothermic hyperkalemic perfusion.

Superior myocardial protection with nicorandil cardioplegia.

OBJECTIVE: The ATP-sensitive potassium channel (K(ATP)) activator nicorandil used as cardioplegic agent may protect the left ventricle during cardiac arrest. Nicorandil in cold blood was compared with standard hyperkalemic blood and crystalloid cardioplegia. METHODS: Twenty-one pigs were randomly assigned to three groups: (1) cold hyperkalemic crystalloid (n=7); (2) cold hyperkalemic blood (n=7); and (3) nicorandil as cardioplegia in cold blood (n=7). Left ventricular mechanical performance, pressure-volume area (PVA) and myocardial oxygen consumption (MVO(2)) were measured before and at 1 and at 2 h after 60 min of cold global ischemia on cardiopulmonary bypass using intraventricular pressure-volume conductance catheters, coronary flow probes and O(2)-content difference. RESULTS: The slope (M(w)) of the stroke work end-diastolic volume relationship, the preload recriutable stroke work relationship, was unchanged after ischemia in the nicorandil group, but was reduced to averaged 62.5% (standard deviation 14) of baseline values in both hyperkalemic perfusions (P<0.05). The slope of the MVO(2)-PVA relationship was unchanged after nicorandil cardioplegia while the slope after hyperkalemic blood and crystalloid cardioplegia increased with 33% (P<0.02) and 52% (P<0.02) of baseline values, respectively. CONCLUSIONS: Nicorandil as sole cardioplegic agent in cold blood given intermittently preserves left ventricular contractility and myocardial energetics significantly better than traditional forms of cardioplegia after cardiac arrest.

Simulations of the effect of currently used grenade harpoons for the killing of whales using a pig-model.

Physical model experiments, as well as simulations of the effects of grenade harpooning on anaesthetized pigs fully immersed in water suggest that the shock effect of the blast from the currently used grenades is relatively minor. Also the animals are not stunned to death, but loose consciousness and subsequently die from hemorrhage. Survival time is therefore very short if the animals are hit in the thorax, and is likely to be further reduced if the charge which is currently used is increased, or, even better, if shrapnel (fragment scattering) grenades are used instead of blast grenades.

Physical activity and peripheral atherosclerosis.

This article describes changes in the muscular blood flow and metabolism in intermittent claudication (pain in the legs during physical work) and the effect of physical training on these factors. The disease (arteriosclerosis obliterans) is characterized by a reduction in the blood flow through muscles and in oxygen uptake, together with increased lactate excretion during work, usually in spite of a developed arterial collateral system. An increased ability to extract oxygen from the blood while the affected muscle metabolism is modified in the direction of greater aerobic capacity can partially compensate for the reduction in blood perfusion. Physical activity which involves large muscle groups and is continued beyond the boundary of pain leads to an increase in both claudication distance (the distance until pain appears during normal walking on the flat) and the walking distance (maximal distance the patient can walk). Since the blood flow is unchanged or reduced, the effect seems not to be due to improved vascular capacity. It has however been shown that training gives rise to further increase both in the ability to extract oxygen from the blood and in the metabolic activity of muscle tissue. It is concluded that, if indications for surgical treatment are not present, training by walking with regular controls constitutes good treatment favourable to health economics and able to improve the patient's quality of life.

Late occlusion of expanded Teflon femoropopliteal graft due to calcification and fracture of implant. Case report.

A case of occlusion and thrombosis in a femoropopliteal Teflon implant is presented. The mechanism was fracture of the calcified capsule around the graft, intermittent stenosis at the fracture site and gradual thrombus formation.

Postinfarction rupture of left ventricular free wall repaired with a glued-on pericardial patch. Case report.

In a 68-year-old man admitted in deep shock, prompt echocardiographic diagnosis of postinfarction left ventricular free wall rupture was followed by probably life-saving pericardiocentesis. At emergency surgery a 2 cm linear tear in the anterolateral wall of the left ventricle was successfully repaired with a glued-on pericardial patch, without infarctectomy or placement of sutures in the infarcted area.

Thromboplastin activities and monocytes in the coronary circulation of reperfused human myocardium. No effect of preoperative treatment with n-3 fatty acids.

In a double-blind study 18 patients were randomized to receive a daily dietary supplement of concentrated ethyl ester compound of n-3 fatty acids or placebo (corn oil) for at least 6 weeks before coronary bypass surgery. Three-fold increase of serum eicosapentaenoic acid and 20% reduction of triglyceride levels were found preoperatively in the n-3 group, while the two groups were similar as regards monocyte and platelet counts, mean platelet volume and monocyte activation as expressed by thromboplastin activities. For determination of transcardiac gradients, coronary sinus and aortic blood were sampled preoperatively 5, 10 and 30 minutes after release of the aortic cross-clamp. In both patient groups the monocyte count was lower in coronary sinus than in aortic blood at 5 and 10 minutes, but the differences were not significant. The platelet counts showed no significant change. In vitro stimulation of monocytes, however, evoked significantly (p < 0.05) less thromboplastin activity in coronary sinus blood than in aortic blood at all three sampling times, without significant intergroup difference. The monocytes most sensitive to activation presumably were trapped in the reperfused myocardium, and this sequestration was not hindered by pretreatment with n-3 fatty acids.

Oxygen-wasting effect of inotropy in the "virtual work model".

In the "virtual work model," left ventricular total mechanical energy (TME) is linearly related to myocardial oxygen consumption (MVO2). This relationship (MVO2-TME) is supposedly independent of inotropic stimulation, vascular loading, and heart rate variations. We reexamined the effect of inotropic stimulation (dopamine) on the metabolic to mechanical energy transfer in nine open-chest anesthetized pigs. Left ventricular mechanical energy was calculated using TME (mean ejection pressure x end-diastolic volume + stroke work), TMEW (end-diastolic volume reduced by unstressed ventricular volume), and the pressure-volume area (PVA). A highly linear relationship between MVO2 and mechanical energy was found for all three indexes during control and dopamine runs (r = 0.87-0.99). The slopes were unaltered by dopamine. y-Axis intercepts were (control vs. dopamine) as follows (in J. beat-1. 100 mg-1; means +/- SD): TME, 0.36 +/- 0.12 vs. 0.61 +/- 0.30 (P < 0.02); TMEW, 0.43 +/- 0.16 vs. 0.72 +/- 0.32 (P < 0.02); and PVA, 0.34 +/- 0.13 vs. 0.60 +/- 0.30 (P < 0.02). We conclude that the virtual work model is dependent on inotropic stimulation and that new insight into myocardial chemomechanical coupling is not added by this concept.

Fibrinolytic treatment of postoperative deep venous thrombosis.

Eleven patients with deep venous thrombosis were treated with streptokinase. Lysis of thrombi and prevention of pulmonay embolism were achieved in eight patients. Bleeding from the operative wound necessitated transfusions in seven patients. Fibrinolytic treatment of deep venous thrombosis lyses the floating portion of the thrombi. Protection against pulmonary embolism may be expected. The fibrinolytic effect of streptokinase is rapid; its value can be answered only by follow-up examinations.

To the management of the solitary thyroid nodule.

Excisional biopsy with peroperative frozen section and later paraffin section examination was performed in 107 consecutive cases of solitary thyroid nodules. Frozen section gave a correct diagnosis in 99 cases (92%). A false benign diagnosis was made in 6 cases, one was inconclusive and one was false malignant (Hürthle cell tumor). Technetium scintigraphy was of no definite diagnostic value. Malignancy was found in 25 cases (23%) in which the whole gland was removed. Multicentric bilateral lobe involvement was encountered in 7 patients. Lack of reliable preoperative diagnostic methods makes liberal excisional biopsy of all solitary thyroid nodules advisable.

Intra- and interobserver variability in ultrasound measurements of abdominal aortic diameter. The Tromsø Study.

OBJECTIVES: To assess the variability of ultrasonographic measurements at different levels of the abdominal aorta. DESIGN: Reproducibility study as part of a population health screening for abdominal aortic aneurysm. MATERIALS AND METHODS: In 1994/1995 a total of 6892 subjects underwent ultrasound examination of the abdominal aorta. Variability of measurements was assessed in the beginning and end of the survey period by inviting 112 randomly selected participants to a second ultrasound scan within 3 weeks of the first scan. The subjects were examined by an experienced radiologist and three sonographers who had been given a short course in ultrasonography. All examiners were blinded to each other's results. RESULTS: Variability was similar in the beginning and end of the survey period. Both the intra- and interobserver variability were less than 4 mm for all sonographers in measurements of maximal infrarenal aortic diameter, and variability was similar for measurements in the anterior-posterior and transverse plane. Variability was greater for measurements at the renal level than aortic bifurcation level. The radiologist had lower variability than the other sonographers. CONCLUSION: Ultrasound measurements of the maximal diameter can be obtained with a high degree of accuracy. Inexperienced sonographers may achieve acceptable performance given appropriate training and surveillance.

[Aortic dissection. A 8-year material from health region 5]. / Aortadisseksjoner. Et åtteårsmateriale fra helseregion 5.

At the University Clinic Tromsø 27 and 16 patients with aortic dissection of Stanford type A and B have been admitted during the last eight years. The treatment strategy has been immediate surgery for type A and a conservative strategy consisting of blood pressure reduction and observation for type B. Nine (33%) of the patients with type A dissections were diagnosed either too late for surgery or at autopsy. Two were deemed too ill for operative treatment. One patient with a chronic type A dissection has been followed up without surgery. The remaining 15 were operated on. Four of these (26%) died within 30 days. Apart from a temporary hemiparesis, no sequelae related to the surgical treatment were observed in the remaining 11 patients. Six of the 16 patients with type B dissections were operated on because of organ ischemia or rupture/threatening rupture. Two died within 30 days. One patient had a prolonged postoperative course owing to multiple organ failure and muscle necrosis. Two of the ten patients with type B dissections who were followed up without surgery died during the observation period. These observations indicate a need for a more aggressive approach to the diagnosis and follow-up of aortic dissections.