Increased fatigability of the gastrocnemius medialis muscle in individuals with intermittent claudication.

BACKGROUND: We attempted to identify possible differences in the contractility of the gastrocnemius medialis (GM) muscle between healthy controls and individuals with peripheral arterial disease (PAD) and intermittent lower-limb claudication. METHODS: The GM muscles of 17 PAD patients and 17 healthy controls were examined with tensiomyography. Single or multiple electrical impulses were used to trigger muscle contractions, and the time and amplitude of contractions were measured. RESULTS: After single-impulse stimulation, the GM muscles of PAD patients showed significantly shorter contraction times (P < 0.001) than the GM muscles of controls. During 1 min of repetitive electrical stimulation, the contraction velocity of the controls' GM muscles typically showed a sustained increase throughout the stimulation period, whereas in PAD patients, a significant decrease in contraction velocity was observed after 30 s. The onset of muscle fatigue was unrelated to the ankle brachial index (ABI) of the examined leg. When the legs of PAD patients with higher and lower ABIs were compared to each other, no significant differences were found regarding the time and amplitude of contraction after single-impulse stimulation. CONCLUSIONS: The GM muscles of individuals with intermittent claudication contract more quickly and fatigue earlier than the GM muscles of healthy controls. Because the contraction time, measured with tensiomyography, reflects the individual's muscle fibre composition, our findings may reflect a shift from type I fibres to type II fibres in the GM muscles of PAD patients. Our data support the idea that calf myopathy is present in claudication-prone patients and, in part, determines the clinical manifestations of PAD.

Aortic valve implantation in the calf: a successful approach using Heartport cannulation and minimally invasive techniques.

BACKGROUND AND AIM OF THE STUDY: Aortic valve replacement (AVR) for mechanical prosthetic valvular testing has not been performed in calves because of anatomic difficulties, and sheep have traditionally been used in this situation. Hemodynamically, however, the calf constitutes an excellent model due to vigorous myocardial contractility, high stroke volumes and high cardiac output, and so has been used for preclinical evaluation of mechanical assist devices and mechanical valves in the mitral and tricuspid positions, which can be approached with relative surgical ease. Recently, a juvenile bovine model has been used to test a newly developed mechanical valve in the aortic position. METHODS: Ten calves (body weight 91+/-11 kg) underwent AVR with a 21-mm mechanical prosthesis via a small left intercostal thoracotomy with the aid of a Heartport cannulation device. A standard cardiopulmonary bypass (CPB) circuit was used. To circumvent the short bovine ascending aorta and to gain additional space to perform the aortotomy, two aortic cannulas were inserted for arterial-systemic perfusion. Nine calves each received a 21-mm experimental trileaflet aortic central flow valve prosthesis, and one calf received a 21-mm St. Jude Medical prosthesis. RESULTS: Mean CPB duration was 154.2+/-44.4 min, and mean ischemic time 80.1+/-15.9 min. Mean study duration was 42.6+/-53.7 days. Three calves were killed prematurely: two on days 2 and 7 due to complications arising from inadvertent entrapment of the right coronary artery ostium by a suture, and one on day 0 due to an accidental overdose of magnesium. Three calves, all of which had a first-version test valve, were killed electively due to valve malfunction secondary to early valvular thrombosis. Four animals (three with the final version valve and one with a standard valve as a control) survived until killed electively (range: 33-172 days). CONCLUSION: Results indicate that replacement of the native bovine aortic valve with a mechanical prosthesis can be performed safely in calves. Complication-free survival of up to six months can be achieved in the growing calf, provided that the test valve design satisfies minimum hemodynamic and coagulation criteria.

Research and development of an implantable, axial-flow left ventricular assist device: the Jarvik 2000 Heart.

Advances in technology and increased clinical need have led to the development of a new type of blood pump. The Jarvik 2000 Heart is an electrically powered, axial-flow left ventricular assist device that has been developed during the past 13 years. Unlike first-generation left ventricular assist devices, which were developed in the 1970s and were designed to totally capture the cardiac output, the Jarvik 2000 is designed to normalize the cardiac output by augmenting the function of the chronically failed heart for extended periods. Design iterations have been tested in 67 animals, and clinical trials have recently begun. Three patients have received the Jarvik 2000 as a bridge to transplantation, and 1 patient is being supported permanently outside the hospital. All 4 patients have improved from New York Heart Association functional class IV to class I, and 2 of them have been discharged from the hospital after heart transplantation. The experimental and clinical results indicate that the Jarvik 2000 can provide physiologic support with minimal complications and is reliable, biocompatible, and easy to implant.

Creation of a distal arteriovenous fistula improves microcirculatory hemodynamics of prosthetic graft bypass in secondary limb salvage procedures.

PURPOSE: In patients with critical limb ischemia, poor distal arterial runoff, and absence of autogenous veins, the use of an artificial graft and an arteriovenous fistula might be a valuable option. However, in these patients little information is available regarding preoperative and postoperative microcirculatory hemodynamics after this type of intervention. METHODS: With the use of intravital capillary microscopy, we studied the effect of distal revascularization on the microcirculation in 26 patients with critical limb ischemia. All patients had had failed vascular reconstructive operations, and artificial grafts were required because of the absence of autogenous veins. Patients were prospectively investigated and divided into two groups: 12 patients received a femorocrural bypass with polytetrafluoroethylene grafts, and 14 patients underwent the same procedure with the creation of an arteriovenous fistula at the site of the distal anastomosis and ligation of the proximal vein. Red blood cell velocity was measured before and after arterial occlusion to determine microcirculatory hemodynamic alterations. RESULTS: Immediate postoperative graft patency was achieved in all 26 patients. The 1-year cumulative graft patency rate was 64% in the group that had creation of an arteriovenous fistula, which was significantly higher (p < 0.01) compared with that in the group in which a fistula was not created (21%). The 1-year cumulative foot salvage rate was 72% in the patients with an arteriovenous fistula and 43% in the patients without a fistula (p < 0.05). Red blood cell velocity increased similarly in both groups after the bypass procedure. Peak and time to peak red blood cell velocity also improved significantly in both groups; however, comparing both groups, peak and time to peak red blood cell velocity were significantly better (p < 0.05) in the patients with an arteriovenous fistula and remained significantly higher during the follow-up period. CONCLUSIONS: In conclusion, creation of an adjunctive arteriovenous fistula at the distal anastomosis of a prosthetic graft appears to improve microcirculatory hemodynamics in the nutritional capillary vascular bed. Improved graft patency and foot salvage rates suggest that this procedure benefits patients with critical limb ischemia who have no usable veins.

Creation of a systemic-to-pulmonary artery shunt by use of an internal mammary artery.

The creation of a systemic-to-pulmonary artery shunt by use of the internal mammary artery (IMA) in a 2-year-old boy with complex congenital heart defects and diminutive pulmonary arteries is described. This procedure may offer advantages over standard methods in selected patients with extremely small pulmonary arteries. The pliability, favorable anatomical position, and growth capability of the IMA reduce chances for complications, such as stenosing, kinking, and stretching of the pulmonary artery, which can cause it to become distorted, making further definitive repair difficult.

Long-term results of the surgical management of symptomatic chronic intestinal ischemia.

We analyzed our surgical experience in 20 patients who underwent revascularization procedures for symptomatic chronic intestinal ischemia caused by atherosclerosis. The group comprised 17 women and 3 men, with an age range of 25 to 71 years (mean 58.6 years). Sixteen patients had postprandial abdominal pain, and 4 had pain not related to eating. The average weight loss was 23.8 lb. Malabsorption and diarrhea were present in 8 patients. The duration of the symptoms was from 4 to 46 months (mean 13.4 months). One patient presented with acute intestinal ischemia following balloon angioplasty reocclusion of a stenotic celiac artery, and 3 underwent surgery for stenosis of a previously placed graft. Five patients had single mesenteric artery involvement, 10 had double-artery involvement, and 5 had significant occlusion in all 3 mesenteric arteries. The major arteries were revascularized whenever technically possible; therefore, 36 arteries were revascularized in 20 patients. Bypass grafts were done in 27 vessels, reimplantation in 7, and endarterectomy with patch angioplasty in 2. The saphenous vein was used in 12 vessels, polytetrafluoroethylene grafts in 8, dacron in 6, and inferior mesenteric vein in 1. The type of revascularization or graft utilized did not affect long-term patency. Two patients had early graft thrombosis and required intestinal resection. All patients survived the operation. At a mean follow-up of 36 months, all 20 patients were alive and asymptomatic with regard to their abdominal complaint. Ten patients (50%) underwent postoperative abdominal angiography; all the grafts were patent.(ABSTRACT TRUNCATED AT 250 WORDS)

Profunda femoral artery pseudoaneurysm after percutaneous transluminal procedures manifested by neuropathy.

The incidence of arterial complications following femoral artery cannulation is low; however, with the increasing number of cardiac diagnostic and interventional procedures, vascular surgeons are being confronted with an increasing number of pseudoaneurysms and arteriovenous fistulas. Swelling and a painful pulsating groin masse are the most frequent presenting symptoms of a common femoral artery false aneurysm. We present the cases of 4 patients who had the unusual finding of a profunda femoral artery pseudoaneurysm after they had undergone cardiac catheterization or percutaneous transluminal coronary angioplasty. The only clinical sign of these patients was femoral neuropathy or neuropalsy caused by femoral nerve compression. Surgical repair of the pseudoaneurysm was successful in all patients. We discuss the reasons for this unusual finding and rare location for a pseudoaneurysm.

Prosthetic graft placement and creation of a distal arteriovenous fistula for secondary vascular reconstruction in patients with severe limb ischemia.

Patients with lower limb ischemia who require reoperation for failed vascular reconstructive surgery can benefit from a surgical technique in which an artificial graft is used and an arteriovenous fistula is created at the site of the distal anastomosis, followed by ligation of the proximal vein. This technique was used in 30 patients who had undergone vascular reconstruction with bypasses from the femoral to the distal tibial, peroneal, or dorsal pedal arteries. Angiography showed occlusion of the superficial femoral and popliteal arteries in all patients with reconstitution of only one small segment in the anterior tibial (n = 12), posterior tibial (n = 11), peroneal (n = 5), or dorsal pedal artery (n = 2). All patients had rest pain and necrosis. Artificial grafts were required because of the absence of autogenous vein. Immediate postoperative graft patency was achieved in all 30 patients. The mean ankle/arm pressure index increased from 0.30 +/- 0.24 to 0.79 +/- 0.31 (p less than 0.01). Graft patency computed by the life-table method was 71% at both 1- and 2-year follow-up. Foot salvage was achieved in 25 of 30 patients after surgery. The results of this study indicate that an aggressive vascular surgical approach in patients with severe ischemia and previous failed bypass procedures is justified. In the absence of autogenous vein, the combination of a prosthetic graft and a distal arteriovenous fistula with ligation of the proximal vein increases graft patency.

Capillary microscopy in patients with vasospastic and arterial occlusive diseases.

Capillary microscopy and its application for diagnosis and therapeutic evaluation in patients with vasospastic and arterial occlusive disease are described in this report. Capillary microscopy is a noninvasive technique for measuring red blood cell velocity and for determining nutritional blood flow in the capillaries of the skin. This method can be applied in distinguishing patients with Raynaud's phenomenon from those with other disorders involving ischemia of the hand. In patients with atherosclerotic disease of the lower limb, microcirculatory observations can help determine how temperature increases and posturally induced microvascular constriction affect limbs with different degrees of ischemia. Capillary microscopy can also be used to help distinguish between patients who respond and those who do not respond to prolonged treatment for such disorders. Because capillary microscopy can be used to assess microcirculatory hemodynamics and autoregulatory mechanisms in cases of severe ischemia, it should be regarded as an essential tool in the evaluation of patients with upper- and lower-limb ischemia.

Innominate artery occlusive disease: surgical approach and long-term results.

We reviewed our experience with 54 patients who underwent innominate artery revascularization during a 10-year period. Their age range was from 16 to 75 years (mean, 49.8 years). The innominate artery alone was involved in 21 patients (39%); the remaining patients had additional arch vessel obstructions. Before operation, neurologic symptoms occurred in 25 patients (46%), arm ischemia related to claudication and microembolization occurred in 8 patients (14%), a combination of symptoms occurred in 17 patients (32%), and no symptoms were noted in 4 patients (8%). The extrathoracic approach to surgery was used in 16 patients (30%). Eleven of the 38 patients in whom the intrathoracic approach was used had endarterectomy of the innominate artery; in three of those, the procedure was combined with left common carotid endarterectomy. Bypass grafts were used in the other 27 patients undergoing procedures with an intrathoracic approach; in six of those, bypass was combined with carotid endarterectomy. No operative deaths occurred. Perioperative revascularization failure occurred in four cases; all of those patients underwent a second revascularization procedure, with a secondary patency rate of 100%. In four patients, late occlusion was noted at 6 months and at 1, 1.5, and 10 years. One patient had a permanent perioperative neurologic deficit in the distribution of the left carotid artery after a combined common carotid endarterectomy/innominate endarterectomy procedure. No neurologic deficits were directly related to the innominate artery territory. Long-term actuarial survival was 83% at 10 years. Early and late graft failures were related to inadequate inflow in bypass grafts, progression of distal disease in arteritis, and primary closure in endarterectomy.

Spontaneous common iliac arteriovenous fistula manifested by acute renal failure: a case report.

Arteriovenous fistulas between the common iliac vessels resulting from spontaneous rupture of aneurysms are rare, with only 31 cases having been reported since 1971. Clinical diagnosis is possible when a unique set of findings is present, namely high-output cardiac failure, a pulsatile abdominal mass associated with a bruit or thrill, and unilateral arterial insufficiency or venous engorgement. Recently, with advancements in diagnostic techniques, the number of cases in which an arteriovenous fistula is found between the common iliac vessels has increased. Diagnosis can be difficult, however, as in the case of one of our patients in whom the predominant sign was acute renal failure. Other reports of renal failure or impairment in the presence of a common iliac fistula have also appeared. Awareness of this phenomenon can help the physician to establish the diagnosis when one or more of the classic signs are absent. Prompt diagnosis and surgical management have contributed to the high incidence of survival in patients with arteriovenous fistulas between the common iliac vessels.