Effects and dose--response relationships of skin cancer and blackfoot disease with arsenic

In a limited area on the southwest coast of Taiwan, where artesian well water with a high concentration of arsenic has been used for more than 60 years, a high prevalence of chronic arsenicism has been observed in recent years. The total population of this "endemic" area is approximately 100,000. A general survey of 40,421 inhabitants and follow-up of 1,108 patients with blackfoot disease were made. Blackfoot disease, so-termed locally, is a peripheral vascular disorder resulting in gangrene of the extremities, especially the feet. The overall prevalence rates for skin cancer was 10.6 per 1000, and for blackfoot disease 8.9 per 1000. Generally speaking, the prevalence increased steadily with age in both diseases. The prevalence rates for skin cancer and blackfoot disease increased with the arsenic content of well water, i.e., the higher the arsenic content, the more patients with skin cancer and blackfoot disease. A dose-response relationship between blackfoot disease and the duration of water intake was also noted. Furthermore, the degree of permanent impairment of function in the patient was directly related to duration of intake of arsenical water and to duration of such intake at the time of onset. The most common cause of death in the patients with skin cancer and blackfoot disease was carcinoma of various sites. The 5-year survival rate after the onset of blackfoot disease was 76.3%; the 10-year survival rate was 63.3% and 15-year survival rate, 52.2%. The 50% survival point was 16 years after onset of the disease.

The pathogenesis of venous limb gangrene associated with heparin-induced thrombocytopenia

BACKGROUND

Platelet-mediated arterial occlusion is a well-recognized cause of limb loss in patients with heparin-induced thrombocytopenia. However, the syndrome of distal ischemic necrosis complicating the deep venous thrombosis (venous limb gangrene) sometimes associated with heparin-induced thrombocytopenia has not been well characterized.

OBJECTIVE

To study the pathogenesis of venous limb gangrene associated with heparin-induced thrombocytopenia.

DESIGN

Characterization (based on descriptive and case-control studies) of a novel syndrome of limb loss and hypothesis testing by analysis of plasma samples.

SETTING

Five university-associated hospitals in one medical community.

PATIENTS

Clinical and laboratory records of 158 patients with heparin-induced thrombocytopenia were reviewed to identify patients with venous limb gangrene (n = 8), limb arterial thrombosis (n = 10), and uncomplicated deep venous thrombosis (n = 58).

MEASUREMENTS

Clinical and laboratory factors associated with venous limb gangrene, including thrombin-antithrombin complexes and vitamin K-dependent procoagulant and anticoagulant factors.

RESULTS

Warfarin treatment was more frequently associated with venous limb gangrene than with limb arterial thrombosis (8 of 8 patients compared with 3 of 10 patients; P = 0.004). The anticoagulant effect of warfarin seemed greater in the 8 patients with venous limb gangrene than in the 58 patients who did not develop gangrene (median International normalized ratio, 5.8 compared with 3.1; P < 0.001). Compared with plasma from controls, plasma from patients with venous limb gangrene had a higher ratio of thrombin-antithrombin complex to protein C activity during warfarin treatment. No hereditable abnormalities of the protein C anticoagulant pathway were seen in any patient.

CONCLUSIONS

Warfarin treatment of deep venous thrombosis associated with heparin-induced thrombocytopenia is a possible cause of venous limb gangrene, perhaps because of acquired failure of the protein C anticoagulant pathway to regulate thrombin generation.

A comprehensive review of epinephrine in the finger: to do or not to do

The prohibition against the use of local anesthetics with epinephrine for digital blocks or infiltration is an established surgical tradition. The present article provides a comprehensive review of all reported digital necrotic and ischemic complications with epinephrine in the digits in an effort to understand whether the current prohibition is based on documented reports. A comprehensive review of articles showing the successful use of local anesthetic with epinephrine in the digits is presented.A review of Index Medicus from 1880 to 1966 and a computer review of the National Library of Medicine database from 1966 to 2000 were performed using multiple keywords. Selected major textbooks from 1900 to 2000 were also reviewed.A total of 48 cases of digital gangrene after anesthetic blocks (mostly using cocaine or procaine) have been reported in the world literature. Only 21 cases involved the use of epinephrine; 17 involved an unknown concentration based on manual dilution. Multiple other concurrent conditions (hot soaks, tight tourniquets, and infection) existed in these case reports, making it difficult to determine the exact cause of the tissue insult. There have been no case reports of digital gangrene using commercial lidocaine with epinephrine (introduced in 1948). Multiple studies involving thousands of patients support the premise that the use of lidocaine with epinephrine is safe in the digits. An extensive literature review failed to provide consistent evidence that our current preparations of local anesthesia with epinephrine cause digital necrosis, although not all complications are necessarily reported. However, as with all techniques, caution is necessary to balance the risks of this technique with the dangers of mechanical tourniquets and upper extremity block anesthesia.

Warfarin-induced skin necrosis and venous limb gangrene in the setting of heparin-induced thrombocytopenia

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is a common, often catastrophic, syndrome that produces the most hypercoagulable of states. Emerging therapeutic strategies use alternative anticoagulants; warfarin's place is being reexamined. Early in the course of warfarin therapy, there may be net procoagulant effects because of the inhibition of protein C. With HIT, it has been suggested that unopposed warfarin can precipitate venous limb gangrene. There are also reports of warfarin-induced skin necrosis. We seek to confirm and increase awareness of the risks of warfarin with HIT.

METHODS

We describe 6 patients with HIT seen at 3 medical centers in whom frank or impending venous limb gangrene, central skin necrosis, or both were temporally related to warfarin initiation.

RESULTS

At warfarin initiation, 5 patients had recognized HIT and 1 had it recognized later. Complications emerged after 2 to 7 days, and consisted of warfarin-induced skin necrosis (n = 5) and venous limb gangrene (n = 2); 1 patient had both. This emerged with unopposed warfarin in 4 patients and as a direct thrombin inhibitor was being withdrawn in 2. All had supratherapeutic international normalized ratios. One patient required leg and breast amputations, and another one died.

CONCLUSIONS

Because of the early effects on protein C, warfarin can precipitate venous limb gangrene and/or skin necrosis in the extreme hypercoagulable milieu of HIT. With HIT, unopposed warfarin should be avoided and caution is needed during transition from a direct thrombin inhibitor. Warfarin should be initiated at modest doses in patients with HIT after platelet recovery. Implications extend to warfarin initiation with other thrombotic diatheses.

Dose-response relationship between peripheral vascular disease and ingested inorganic arsenic among residents in blackfoot disease endemic villages in Taiwan

The purpose of this study was to examine the correlation between previous arsenic exposure and peripheral vascular disease after stopping consumption of high-arsenic artesian well water for more than two decades in blackfoot disease endemic villages in Taiwan. A total of 582 adults (263 men and 319 women, aged 52.6 +/- 10.6 years) living in these villages underwent Doppler ultrasound measurement of systolic pressures on bilateral ankle (posterior tibial and dorsal pedal) and brachial arteries and estimation for long-term arsenic exposure. The diagnosis of peripheral vascular disease was based on an ankle-brachial index (the ratio between ankle and brachial systolic pressures) <0.90 on either side. Three indices of arsenic exposure were estimated: (1) duration of living in blackfoot disease endemic villages; (2) duration of artesian well water consumption; and (3) cumulative arsenic exposure in mg/l-years based on the detailed history of residential addresses and artesian well water consumption and the arsenic concentration in artesian well water. Multiple logistic regression analysis was used to assess the association between peripheral vascular disease and arsenic exposure. A dose-response relation was observed between the prevalence of peripheral vascular disease and the long-term arsenic exposure. The odds ratios (95% confidence intervals) after adjustment for age, sex, body mass index, cigarette smoking, serum cholesterol and triglyceride levels, diabetes mellitus and hypertension were 2.77 (0.84-9.14), and 4.28 (1.26-14.54) for those who had cumulative arsenic exposure of 0.1-19.9 and > or = 20.0 mg/l-years, respectively, compared with those who were not exposed. This study suggests a close relation between long-term arsenic exposure and peripheral vascular disease in blackfoot disease endemic villages in Taiwan after stopping consumption of artesian well water.

Heparin-induced thrombocytopenia: a ten-year retrospective

The past decade has seen many important advances in the pathogenesis, clinical and laboratory diagnosis, and management of heparin-induced thrombocytopenia (HIT), one of the most common immune-mediated adverse drug reactions. HIT is caused by IgG antibodies that recognize complexes of heparin and platelet factor 4, leading to platelet activation via platelet Fc gamma IIa receptors. Formation of procoagulant, platelet-derived microparticles, and, possibly, activation of endothelium generate thrombin in vivo. Thrombin generation helps to explain the strong association between HIT and thrombosis, including the newly recognized syndrome of warfarin-induced venous limb gangrene. This syndrome occurs when acquired protein C deficiency during warfarin treatment of HIT and deep venous thrombosis leads to the inability to regulate thrombin generation in the microvasculature. The central role of HIT antibodies in causing HIT, as well as refinements in laboratory assays to detect these antibodies, means that HIT should be considered a clinicopathologic syndrome. The diagnosis can be made confidently when one or more typical clinical events (most frequently, thrombocytopenia with or without thrombosis) occur in a patient with detectable HIT antibodies. The central role of thrombin generation in this syndrome provides a rationale for the use of anticoagulants that reduce thrombin generation (danaparoid) or inhibit thrombin (lepirudin).

Statin use before diabetes diagnosis and risk of microvascular disease: a nationwide nested matched study

BACKGROUND

The role of statins in the development of microvascular disease in patients with diabetes is unknown. We tested the hypothesis that statin use increases the risk of diabetic retinopathy, diabetic neuropathy, diabetic nephropathy, and gangrene of the foot in individuals with diabetes.

METHODS

We identified all patients living in Denmark who were aged 40 years or older and were diagnosed with incident diabetes between Jan 1, 1996, and Dec 31, 2009. We obtained patients' data from the Danish Patient Registry and information on drug use from the Danish Registry of Medicinal Product Statistics. We randomly selected 15,679 individuals from the database who had used statins regularly until their diagnosis of diabetes (statin users) and matched them in a 1:3 ratio with 47,037 individuals who had never used statins before diagnosis (non-statin users). Our primary outcome was to compare the cumulative incidence of diabetic retinopathy, diabetic neuropathy, diabetic nephropathy, or gangrene of the foot in statin users versus non-statin users. We analysed data with Cox regression models, adjusted for covariates including sex, age at diabetes diagnosis, and method of diabetes diagnosis. To address potential biases between statin users and non-statin users, we made adjustments to our analysis with a propensity score and with other factors. Median follow-up was 2·7 years (range 0-13).

FINDINGS

During 215,725 person-years of follow-up, 2866 patients developed diabetic retinopathy, 1406 developed diabetic neuropathy, 1248 developed diabetic nephropathy, and 2392 developed gangrene of the foot. Compared with non-statin users, statin users had a lower cumulative incidence of diabetic retinopathy (hazard ratio 0·60, 95% CI 0·54-0·66; p<0·0001), diabetic neuropathy (0·66, 0·57-0·75; p<0·0001), and gangrene of the foot (0·88, 0·80-0·97; p=0·010), but not diabetic nephropathy (0·97, 0·85-1·10; p=0·62). These results were similar after adjusting for the competing risk of death, after matching for a propensity score, after adjusting for visits to a family doctor, and by stratification on covariates. The corresponding multivariable adjusted hazard ratio for risk of diabetes in the total population was 1·17 (95% CI 1·14-1·21; p<0·0001).

INTERPRETATION

Use of statins before diagnosis of incident diabetes was not associated with an increased risk of microvascular disease. Whether statins are protective against some forms of microvascular disease-a possibility raised by these data-will need to be addressed in other studies similar to ours, in mendelian randomisation studies, and preferably in randomised controlled trials.

FUNDING

Herlev Hospital, Copenhagen University Hospital.

Heparin-induced thrombocytopenia: IgG-mediated platelet activation, platelet microparticle generation, and altered procoagulant/anticoagulant balance in the pathogenesis of thrombosis and venous limb gangrene complicating heparin-induced thrombocytopenia

Until recently, the confusing clinical profile of HIT and the widespread unavailability of reliable diagnostic assays have conspired to produce under-recognition-if not frank skepticism-of the clinical importance of HIT. However, during the 1990s, HIT has emerged as one of the major-if not the most important-immunohematologic problems in clinical medicine. The clinical and laboratory investigations summarized here have contributed to a greater understanding of the frequency, clinical spectrum, pathogenesis, laboratory diagnosis, and-potentially-the prevention of this important drug allergy. Further, the demonstration of increased platelet procoagulant activity and, thrombin generation in HIT, together with insights into the pathogenesis of a new clinicopathologic syndrome (venous limb gangrene), help explain how a disorder characterized by IgG-mediated platelet activation can lead to such diverse clinical sequelae as venous thrombosis, pulmonary embolism, disseminated intravascular coagulation, and venous limb gangrene. These studies should lead to improved treatment of HIT (new emphasis on suppression of thrombin generation, eg, hirudin and its analogs), future avoidance of HIT (preparation of low-molecular-weight heparins and heparinoids that are less immunogenic), and a greater understanding of the interaction between platelet activation and procoagulant/anticoagulant processes.

Venous limb gangrene during warfarin treatment of cancer-associated deep venous thrombosis

BACKGROUND

The cause of cancer-associated venous limb gangrene is unknown but could paradoxically be due to warfarin.

OBJECTIVE

To determine the pathogenesis of venous gangrene in a patient with cancer.

DESIGN

Case report.

SETTING

University hospital in Ontario, Canada.

PATIENT

66-year-old woman with metastatic lung cancer and deep venous thrombosis.

MEASUREMENTS

Levels of vitamin K-dependent factors, additional coagulation factors, and thrombin-antithrombin complexes (marker of thrombin generation).

RESULTS

During warfarin use, venous limb gangrene developed when the international normalized ratio (INR) reached 6.0 (therapeutic range, 2.0 to 3.0); at this time, the level of protein C (a vitamin K-dependent natural anticoagulant) was severely reduced, but thrombin-antithrombin complexes remained markedly elevated. The supratherapeutic INR was explained by the greatly reduced levels of factor VII, which correlated closely with protein C levels; therefore, the high INR was a surrogate marker for severely reduced protein C activity.

CONCLUSION

Warfarin may contribute to the pathogenesis of cancer-associated venous limb gangrene by leading to severe depletion of protein C while at the same time failing to reduce thrombin generation.

Symmetrical peripheral gangrene: association with noradrenaline administration

The syndrome of symmetrical peripheral gangrene is characterised by distal ischaemic damage in two or more extremities, without large vessel obstruction. Four patients with bilateral pedal ischaemia are described and their haemodynamic profiles presented. In all four cases the syndrome developed in association with noradrenaline administration, sepsis and DIC, despite a high cardiac output and a low calculated systemic vascular resistance index. Early treatment with epoprostenol was instituted in the final case and was successful.

Vascular events associated with alpha interferon therapy

Alpha Interferon (IFN) is a biological agent used for the therapy of an increasing number of diseases, either as an established effective therapeutic tool or in the context of clinical trials. The use of IFN may be complicated by serious adverse reactions. We describe here the clinical course of a variety of vasculopathic complications in association with IFN-therapy in 12 patients with the diagnosis of chronic myeloid leukemia and 1 patient with malignant melanoma treated at our institute. Vascular manifestations in these patients include Raynaud's phenomena, digital ulcerations and gangrene, pulmonary vasculitis, pulmonary hypertension and thrombotic thrombocytopenic purpura/hemolytic uremic syndrome (TTP/HUS). These reactions occurred after 3 months to 3 years of 3-10 million units (MU) daily IFN therapy. Concomitant administration of hydroxyurea (HU) was noted in 5 patients. Discontinuation of IFN and initiation of immunosuppressive therapy brought about a complete resolution or arrested progression of these reactions. IFN-therapy may be complicated by severe vasculopathic/vasospastic complications that usually improve after its discontinuation. Possible underlying mechanisms for these complications are discussed. The early diagnosis of these complications may be vital and IFN should be immediately discontinued when early signs of these complications become evident.

An overview on peripheral vascular disease in blackfoot disease-hyperendemic villages in Taiwan

The arsenic-related peripheral vascular disease found to be endemic along the southwestern coast of Taiwan is reviewed. In the early 20th century a strange disease involving the lower extremities characterized by typical clinical symptoms and signs of progressive arterial occlusion was reported in a confined area located along the southwestern coast of Taiwan. The disease was locally called "blackfoot disease" because of its gangrenous appearance involving the feet of the patients. The prevalence of this disease ranged from 6.51 to 18.85 per 1,000 population in different villages. Epidemiologic studies revealed that blackfoot disease was associated with the consumption of artesian well water containing high levels of arsenic. High co-occurrence of blackfoot disease and arsenic-related skin lesions such as hyperpigmentation, hyperkeratosis, and skin cancer was also observed. Recent studies also confirmed the association of preclinical peripheral vascular disease with arsenic exposure in a dose-response pattern. Subclinical arterial insufficiency and defects in cutaneous microcirculation can also be demonstrated in seemingly normal subjects living in the endemic villages. The incidence of clinical manifestation of blackfoot disease decreased dramatically after the implementation of tap water in these villages over the past 2-3 decades. The atherogenicity of arsenic could be associated with its effects on hypercoagulability, endothelial injury, smooth muscle cell proliferation, somatic mutation, oxidative stress, and apoptosis. However, its interaction with some trace elements and its association with hypertension and diabetes mellitus could also explain part of its higher risk of developing atherosclerosis.

Thrombotic microangiopathy and digital necrosis: two unrecognized toxicities of gemcitabine

We report one new case of hemolytic-uremic syndrome (HUS) and one case of digital necrosis after treatment with gemcitabine (Gemzar). Case 1, a 34-year-old man, was given first-line metastatic treatment with gemcitabine for a adenocarcinoma of the pancreas. After a cumulative dose of 10 000 mg/m2 gemcitabine, the onset of subacute renal failure associated with hemolytic anemia of mechanical origin was observed. A diagnosis of probable gemcitabine-induced thrombotic microangiopathy was arrived at. Symptoms resolved after stopping the chemotherapy, in spite of the progression of the disease. Case 2, a 61-year-old man, was administered a combination of gemcitabine and a platinum salt as first-line metastatic treatment for carcinoma of the bladder urothelium. Following a cumulative dose of 10 000 mg/m2 of gemcitabine, the patient suffered from bilateral peripheral vascular disease of somewhat acute onset with hemorrhagic lesions of the finger pads that became necrotic. The work-up was negative and a causal relationship was attributed to gemcitabine. The patient made good progress when given an i.v. infusion of Ilomedine (iloprost trometamol) and chemotherapy was withdrawn. We conclude that gemcitabine must be added to the list of drugs that cause HUS and necrotizing vasculitis.

The harmful chemistry behind krokodil (desomorphine) synthesis and mechanisms of toxicity

"Krokodil" is the street name for the homemade injectable mixture that has been used as a cheap substitute for heroin. Its use begun in Russia and Ukraine and nowadays is being spread over several other countries. Desomorphine is the semi-synthetic opioid claimed to be the main component of krokodil and considered to be responsible for its psychoactive characteristics. The starting materials for desomorphine synthesis are codeine tablets, alkali solutions, organic solvent, acidified water, iodine and red phosphorus, all of which are easily available in retail outlets, such as supermarkets, drugstores, etc. The resulting product is a light brown liquid that is called krokodil. People who inject krokodil present a great variety of serious signs and symptoms, including thrombophlebitis, ulcerations, gangrene, and necrosis, quickly evolving to limb amputation and death. These effects are thought to result from the toxic components produced as byproducts during the homemade drug synthesis. In this work, we reviewed several aspects of krokodil use, including its epidemiology, pharmacology and the chemical properties of the main active ingredient (desomorphine). To enhance our understanding of the clinical and toxic effects and to support the implementation of harm reduction measures, we also describe the "bathtub chemistry" of krokodil and the content of the final solution.

Transition to an oral anticoagulant in patients with heparin-induced thrombocytopenia

Recommendations for transitioning from therapy with heparin or a low-molecular-weight heparin preparation to therapy with an oral anticoagulant in patients with acute venous or arterial thromboembolism have undergone several changes during the last two decades. Physicians are now comfortable with beginning treatment with an oral anticoagulant once the diagnosis is confirmed, and loading doses are no longer considered to be necessary. Exceptions to early transition may be necessary in patients with an extensive iliofemoral or axillary-subclavian vein thrombosis or pulmonary embolism where thrombolytic agents may be indicated, or in individuals who require surgery or other invasive procedures, or if there are concerns about bleeding. The avoidance of early transition to oral anticoagulants in patients with acute heparin-induced thrombocytopenia also has been advised because of the potential for further thrombotic complications, including venous limb gangrene and warfarin-induced skin necrosis.

Pathogenesis of gangrene following intra-arterial injection of drugs: a new hypothesis

We have demonstrated the toxicity of diazepam and the safety of ketamine hydrochloride following intra-arterial injection in an anaesthetized animal model. The pathogenesis of gangrene following intra-arterial injection of drugs is unclear. Clinical reports and this experiment suggest that it only follows injection of highly membrane-soluble drugs. Early swelling and disruption of capillary endothelial cells were demonstrated after intra-arterial injection of diazepam and thiopentone. We believe that a theory of pathogenesis based on this finding is consistent not only with our experimental findings, but with known in vitro effects of membrane soluble drugs on cell membranes and the clinical features following intra-arterial injections in both human subjects and in animals.