Muscle Pumping in the Dependent Leg

Varicose Veins in Active People

In brief: Varicose veins can affect active HMM people of all ages, although the incidence gradually increases with age. Conservative treatment (eg, support stockings or exercise modification) often is sufficient, but in severe cases, injection therapy or ligation or removal of the varicose veins may be appropriate. Understanding the pathophysiology involved and the management options available can help physicians counsel patients with this common disorder.

Influence of vagal cooling on cardiac output in normal and beta-blocked exercising dogs

To study the relative influence of parasympathetic and sympathetic innervation on the early adaptation of cardiac output (CO) to exercise, we determined the time constant and amplitude of the CO change in dogs following a stepwise increase in treadmill velocity. The animals were studied during control conditions, beta-blockade, vagal blockade and combined beta-blockade and vagal blockade. To measure CO, an electromagnetic flow probe was implanted around the ascending aorta. Vagal activity was blocked with coolers, implanted around the cervical vagosympathetic trunks. The time constant during beta-blockade (12.1 s) was not different from the control situation (11.4 s), but during vagal cooling it increased significantly (16.2 s), and with combined vagal cooling and beta-blockade it rose to 20.7 s. Thus the increase in cardiac output with exercise is accelerated most by the loss of vagal tone and to a lesser degree by sympathetic activation. The amplitude of the change in CO during control was 112%. Heart rate (HR) rose by 74% and stroke volume (SV) by 22%. Beta-blockade lowered the initial CO but did not alter the percentage increase. Vagal cooling, with or without beta-blockade, caused an increased initial HR but did not influence basal CO because of a concomitant reduction in SV. Exercise now increased HR less (21% and 30%, respectively) and SV more (52% and 52%) but the increase in CO did not change significantly (87% and 97%).(ABSTRACT TRUNCATED AT 250 WORDS)

Venous capacity, venous refill time and the effectiveness of the calf muscle pump in normal subjects

With strain gauge plethysmography various procedures to assess the competence of the venous system in the lower leg were compared in 10 normal subjects. The reproducibility and ease of use were established, and normal values were obtained. It is concluded, that measurements in the sitting position are preferable to those in the standing position. To measure the venous capacity, the dependency test is the method of choice. Rhythmic exercise to assess the effectiveness of the calf muscle pump can be restricted to five successive contractions. The refill time after exercise is not a suitable parameter to assess the competence of the venous valves.

Effect of vein pump activation upon muscle blood flow and venous pressure in the human leg

The effect of vein pump activation upon superficial venous pressure and blood flow in human skeletal muscle tissue was studied in 7 healthy subjects. Blood flow was measured in the anterior tibial muscle by the local 133Xe washout technique. The subjects were placed on a steeply tilted couch in nearly erect position. The vein pump in gastrocnemius-soleus muscles was activated by heel-raisings, and the anterior tibial muscle remained relaxed during this procedure. Blood flow in the resting anterior tibial muscle was constant before, during and after 20 heel-raisings per min. A more heavy exercise with 40 heel-raisings per min increased blood flow about 100%. This increase in blood flow was absent during venous stasis (40 mmHg), and in areas infiltrated with lidocaine. It is concluded, that intense dynamic exercise in gastrocnemius-soleus muscles, in erect humans, increased blood flow considerably in another crural muscle remaining in the resting state. The present study strongly suggests, that the observed increase in blood flow, was associated with a decrease in regional subfascial venous pressure to below the threshold level of the local sympathetic veno-arteriolar reflex.

Physiologic Intervention in Cardiovascular Nuclear Medicine

Homeostasis of cardiac output is maintained by a complex intergration of many physiologic responses, both central and peripheral, including pulse,the contractile state of the ventricle, and pre-and after load. In the abnormal ventricle at rest, any or all of the measurable parameters that define left ventricular function may be normal. However, in disease states, exercise can provoke abnormalities in these parameters indicating a reduction in myocardial reserve. Regional asynergy occurs in patients with significant ischemic heart disease during exercise reflecting a local supply-demand mismatch. Recently, radionuclide ventriculography has been combined with exercise techniques in attempts to elucidate details of the normal and abnormal ventricular response to stress noninvasively. The majority of data describe the response of the ventricle during graded supine bicycle exercise. The normal response is to increase myocardial contractility, reducing end-systolic volume, while end-diastolic volume remains constant. This results in an increase in ejection fraction. In ischemic ventricles, regional asynergy develops and ejection fractions may either fall or fail to rise. This appears to be accomplished by an increase or no change in the end-diastolic volume, with an increase in end-systolic volume, particularly in patients with angina during exercise. Radionuclide methods can be applied to large mumbers of patients providing informaton that is unobtainable by more invasive procedures. This review traces the development of knowledge of the ventricular response to exercise, emphasizing the role of radionuclide ventriculography. Although radionuclide angiography has the capacity for advancing the understanding of the ventricular response to exercise, the technical limitations of this technique in specific diagnostic conditions has yet to be defined adequately.