Nicardipine in the treatment of Raynaud's phenomenon. Dissociation of platelet activation from vasospasm

A new calcium channel blocker, nicardipine, was studied for treatment of Raynaud's phenomenon in a double-blind, placebo-controlled, crossover trial during the winter months. Clinical response was assessed by a patient-kept diary of symptoms and finger systolic pressure that was measured at room temperature and during cold challenge. In vivo platelet activation was determined by measuring plasma levels of the platelet-specific proteins, beta-thromboglobulin and platelet factor 4. When treatment with placebo was compared with treatment with nicardipine, no significant differences were found in the number of Raynaud's attacks per day, the severity of attacks, change in character in Raynaud's phenomenon, use of hands in winter months, patient assessment of medication or objective measurements of finger systolic pressure, and critical closing temperature. There was a reduction of plasma levels of beta-thromboglobulin and platelet factor 4 in the overall study group while taking nicardipine compared with that during the placebo period (mean change 5.0 +/- 2.4 ng/ml, P = 0.054, and 1.4 +/- 0.6 ng/ml, P less than 0.01, respectively). These results demonstrate that while nicardipine was not effective in reducing the episodes of Raynaud's phenomenon, it did inhibit in vivo platelet activation. These findings suggest that platelet activation is not the primary event in the pathogenesis of acute vasospasm in Raynaud's phenomenon, since reduction of platelet activation by the drug did not change the severity of vasospasm.     

Nifedipine as a therapeutic modality for raynaud's phenomenon

Eight patients with Raynaud's phenomenon were entered into a double-blind crossover study of nifedipine versus placebo, with 7 patients undergoing finger pleth-ysmography before and after sublingual nifedipine ad-ministration. While receiving nifedipine, all patients reported decreased frequency and severity of attacks, and 4 of 5 had digital ulcer healing. Total finger blood flow increased in 5 of 6 patients after treatment with sublingual nifedipine. This preliminary study indicates that nifedipine may be a useful agent for treatment of digital vasospasm.     

Nifedipine in the treatment of Raynaud's phenomenon. Evidence for inhibition of platelet activation

Platelet activation has been reported to occur in patients with Raynaud's phenomenon; however, the effect of calcium channel blockers and thromboxane synthetase inhibitors has not been previously studied. The effect of two drugs that potentially inhibit platelet activation were studied: nifedipine, a calcium channel blocker, and dazoxiben, a specific thromboxane synthetase inhibitor. Two platelet-specific proteins released during platelet activation, beta-thromboglobulin and platelet factor 4, were measured during a double-blind clinical trial of these two drugs in patients with Raynaud's phenomenon. The plasma beta-thromboglobulin level was significantly elevated in the patient population (53.8 +/- 7.6 ng/ml) during the placebo period compared with that in a normal control population (27.0 +/- 3.1 ng/ml) (p less than 0.01). The plasma platelet factor 4 level was 8.7 +/- 2.2 ng/ml in the patients compared with 6.5 +/- 1.0 ng/ml in the normal subjects (p = NS). These findings indicate the presence of in vivo platelet activation in patients with Raynaud's phenomenon. Nifedipine lowered the levels of beta-thromboglobulin to near the normal range (33.4 +/- 4.6 ng/ml). The inhibition of platelet activation by nifedipine was associated with clinical improvement in Raynaud's phenomenon with fewer and less intense episodes. Beta-thromboglobulin was not lowered by dazoxiben (58.1 +/- 9.0 ng/ml) compared with the placebo. The reduction of beta-thromboglobulin levels by nifedipine indicates that in vivo platelet activation was inhibited by this agent. Since this was associated with a reduced frequency of attacks, it is not clear whether this was a direct effect of the drug on platelet activation, leading to decreased frequency of vasospasm, or an effect on vascular smooth muscle leading to decreased vasospasm and a secondary decrease in platelet activation.     

A double blind, randomised, multicentre comparison of two doses of intravenous iloprost in the treatment of Raynaud''s phenomenon secondary to connective tissue diseases.

OBJECTIVE--To compare low (0.5 ng/kg/min) and standard dose (2 ng/kg/min) iloprost (a stable carbacyclin analogue of prostacyclin) in patients with Raynaud''s phenomenon secondary to connective tissue disorders. DESIGN--Double blind, random allocation, three six hour infusions on consecutive days. Follow up period eight weeks. SETTING--Rheumatology units, five teaching hospitals. PATIENTS--55 Patients with Raynaud''s phenomenon (greater than seven attacks per week), 32 secondary to well documented classical progressive systemic sclerosis (American Rheumatism Association criteria), 11 CREST syndrome, 5 mixed connective tissue disease, 1 rheumatoid arthritis, 1 Sjögren''s syndrome, 1 childhood dermatomyositis, and 4 abnormal nailfold capillaroscopy and antibody profiles but no definite diagnosis. INTERVENTIONS--All other treatment for Raynaud''s phenomenon was discontinued two weeks before entry. 28 Patients were randomly allocated to receive the low dose, 27 the standard dose. Differing dilutions allowed infusion rates to be started at 10 ml/h with increments of 10 ml/h every 15 minutes until infusion rates reached 0.5 ng/kg/min and 2 ng/kg/min respectively. MAIN OUTCOME MEASURE(s)--Reduction in frequency, duration, and severity of attacks of Raynaud''s phenomenon. Assessment of ulcer and ischaemic lesion healing. RESULTS--Both dosage regimens were equally effective in reducing severity, frequency, and duration of Raynaud''s attacks. Ulcer healing occurred to similar degree in both treatment groups (standard dose 44%, low dose 39%). Low dose was associated with significantly fewer side effects. CONCLUSIONS--Both dosage regimens reduce severity of Raynaud''s phenomenon and encourage ulcer healing. Low dose was associated with fewer side effects and was better tolerated by the patients.     

Paroxysmal Dysarthria and Raynaud's Phenomenon in the Tongue

ABSTRACT Three patients suffering from systemic scleroderma and Raynaud's phenomenon in the digits as well as the tongue are reported. Following exposure to cold, a vasospasm was observed in the digits and the tongue accompanied by severe dysarthria. These striking oral symptoms had been overlooked for years in the medical ward. It is recommended to question all patients with Raynaud's phenomenon about visceral manifestations during the digital attacks.     

Paroxysmal Dysarthria and Raynaud's Phenomenon in the Tongue

Abstract Three patients suffering from systemic scleroderma and Raynaud's phenomenon in the digits as well as the tongue are reported. Following exposure to cold, a vasospasm was observed in the digits and the tongue accompanied by severe dysarthria. These striking oral symptoms had been overlooked for years in the medical ward. It is recommended to question all patients with Raynaud's phenomenon about visceral manifestations during the digital attacks.     

Modified‐release sildenafil reduces Raynaud's phenomenon attack frequency in limited cutaneous systemic sclerosis

Objective

To examine the effect of sildenafil in patients with Raynaud's phenomenon (RP) secondary to limited cutaneous systemic sclerosis (lcSSc).

Methods

In this double‐blind, placebo‐controlled study, 57 patients with RP secondary to lcSSc were randomized to receive modified‐release sildenafil 100 mg once daily for 3 days followed by modified‐release sildenafil 200 mg once daily for 25 days or placebo. The primary assessment was the percentage change in the number of RP attacks per week in the per‐protocol population. Secondary end points included Raynaud's Condition Score, duration of attacks, RP pain score, endothelial dysfunction assessed by a peripheral arterial tonometric (PAT) device, and serum biomarker levels.

Results

The mean percentage reduction from baseline to day 28 in attacks per week was greater for modified‐release sildenafil than for placebo (−44.0% versus −18.1%, P = 0.034); the mean number of attacks per week improved from 25.0 at baseline to 19.3 after placebo treatment and from 30.5 to 18.7 after modified‐release sildenafil treatment (P = 0.244). Decreases from baseline in Raynaud's Condition Score, duration of attacks, and RP pain score were not significantly different between groups. Mean values and changes from baseline in PAT responses and serum biomarker levels were similar between groups. The most frequent adverse events were headache and dyspepsia; the majority of adverse events were mild or moderate.

Conclusion

Our findings indicate that modified‐release sildenafil reduced attack frequency in patients with RP secondary to lcSSc and was well tolerated. Modified‐release sildenafil may be a treatment option in this patient population.

     

Hypothyroidism,Raynaud's phenomenon,and acute myocardial infarction in a young woman

We describe an acute inferior myocardial infarction in a 29-year-old woman with normal coronary arteries. She has suffered from Raynaud's phenomenon in the fingers for several years. Manifest thyroid deficiency was discovered during hospitalization. A functional-type link between hypothyroidism and myocardial infarction via vasospasm manifested as Raynaud's phenomenon is proposed as one possible etiology for the syndrome of myocardial infarction in young women.     

Reversible cerebral vasoconstriction syndrome (RCVS) in antiphospholipid antibody syndrome (APLA): the role of centrally acting vasodilators. Case series and review of literature

Reversible cerebral vasoconstriction syndrome (RCVS) is Raynaud's phenomenon of the brain. Changes in neurological function are dependent upon which areas of the brain are deprived of normal blood flow. Antiphospholipid antibody syndrome (APLA) is a common cause of Raynaud's phenomenon that can occur anywhere in the body, including the brain. Management of CNS vasospasm generally involves the use of centrally acting calcium channel blockers, which have been shown to relieve the associated headaches and transient neurological symptoms associated with it. Three patients with APLA and RCVS from our clinics are illustrated. It is demonstrated that the use of centrally acting calcium channel-blocking drugs, such as nimodipine, which prevent and reverse CNS vasospasm, led to clinical improvement in our patients over the course of 5–9 years. All of them had MRIs done at the initiation of therapy and 5–9 years after being on therapy. MRI measures of T2 lesion volumes (LVs) and number were obtained. All three patients had a good response in controlling clinical symptoms related to CNS vasospasm, Raynaud's phenomenon, visual disturbances, confusion, headaches, and hearing loss. There was also a resolution in the MRI findings of these patients. This case series of three patients shows a clinical improvement and decrease in T2 LV and number in patients with APLA and Raynaud's syndrome on centrally acting calcium channel blockers. RCVS is much more common than that currently appreciated. APLA is the common cause of RCVS. Further studies are needed to determine the optimal methods to diagnose RCVS and optimal therapies to treat it.     

The treatment with N-acetylcysteine of Raynaud’s phenomenon and ischemic ulcers therapy in sclerodermic patients: a prospective observational study of 50 patients

N-Acetylcysteine is useful in the short-term treatment of severe Raynaud's phenomenon and digital ulcers (DU) in patients with systemic sclerosis (SSc), but its long-term effects are largely unknown. The aim of this study was to report long-term outcome (median follow-up 3 years) in a prospective study of a cohort of 50 consecutive patients with SSc who received N-acetylcysteine (NAC) infusional therapy every 2 weeks. We observed a reduction of DU/patient/year (4.5?±?3.1 vs 0.81?±?0.79) and DU ulcer visual analog scale (VAS; 6.88?±?2.62 vs 3.20?±?1.80), a decrease of the Raynaud’s phenomenon (RP) number attacks (7.18?±?3.87 vs 3?±?1.92), and RP VAS (6.24?±?1.92 vs 3.62?±?1.48). In this study, we did not observe serious adverse events in patients. Minor side effects were flushing (two patients) and headache (one patient). NAC infusion was generally well tolerated, and nobody had to discontinue the treatment. In conclusion, long-term therapy with NAC, in patients with SSc, has a durable effectiveness on ischemic ulcers and Raynaud's phenomenon.     

Evaluation of Test Characteristics for Outcome Measures Used in Raynaud's Phenomenon Clinical Trials

Objective

Randomized controlled trials (RCTs) in Raynaud's phenomenon (RP) have shown conflicting efficacy data. Also, there is no consensus on the outcome measures that should be used. Our objectives were to assess the reliability of individual core set measures used in 3 RCTs, evaluate the placebo response for individual core set measures, and determine if a composite of individual core set measures will decrease the placebo response, which may improve our ability to see treatment effects in future trials.

Methods

We analyzed core set measures from 249 patients in the placebo‐treated groups from 3 RCTs. Core set measures analyzed included the Raynaud's Condition Score (RCS); patient and physician assessment of RP; pain, numbness, and tingling during an RP attack; average number of attacks/day; and duration of attacks. Intraclass correlation coefficients (ICCs) were calculated during the run‐in period to the RCTs.

Results

ICCs of ≥0.70 were observed for the RCS, attack symptoms, and average attacks/day. A high placebo response rate was observed for all individual core measures except the duration of attacks. For the RCS, the placebo response ranged from 56% with ≥10% improvement to 19.5% with ≥60% improvement. In contrast, placebo response rates of 10–20% were observed when several core set measures were combined to develop a composite score.

Conclusion

Outcome measures used in RCTs of RP are associated with marked variability. A combination of outcome measures is associated with low placebo responses. Future studies are needed to assess if a composite score will be able to differentiate placebo from an effective agent.     

Platelet activation in angina at rest. Evidence by paired measurement of plasma beta-thromboglobulin and platelet factor 4

Indexes of in vivo platelet activation, beta-thromboglobulinand platelet factor 4 were measured in triplicate in plasmafrom venous blood of 69 patients with proven ischaemic heartdisease (IHD), discarding samples with a ratio of the plasmaconcentrations of the two proteins <2.6, in order to ruleout sampling artifacts. Compared with 60 control volunteers,differences were not significant [for beta-thromboglobulin controls(ng ml^–1, mean±SD) 27.8–8.6, ischaemic patients32.3±17.1; for platelet factor 4 controls 4.3±1.4,ischaemic patients 5.9±5.7]. However, when patients werestratified according to disease activity (Group I—;patientswithout spontaneous ischaemic episodes at rest during 4 daysof continuous electrocardiographic monitoring; Group II—patientswith <l ischaemic episode/day; Group III—patients with>l episode/day), these indexes were increased in ‘active’patients (for beta-thromboglobulin, in Group II—32.4±10.5ng ml^–1, P<0.05 vs. Group I; in Group III—42.6±14.6ng ml^–1, P<0.01 vs. Group I, P<0.05 vs. control.Platelet factor 4 was increased only in Group III—8.9±7.2ngml^–1, P<0.05 vs. control). Beta-thromboglobulin andplatelet factor 4 were 25.0±6.7 ng ml^–1 and 4.9±4.8ng ml^–1, respectively, in Group I (P=NS vs. control).A relationship with the number of spontaenous ischaemic episodesat rest was confirmed by linear regression analysis (in GroupIII patients for beta-thromboglobulin: r=0.76, P<0.01, andfor platelet factor 4 r=0.62, P<0.01). Levles were not elevatedin patients with pervious myocardial infarction without ischaemiaat rest and/or patients with stable angina, and were not influencedby the occurrence of a positive exercise stress test. Coronaryangiograms of ischaemic patients were analyzed to assess theextent and severity of atherosclerotic involvement; for bothextent and severity, involvement was similar in the three groups.These data support the hypothesis of the occurrence of plateletactivation in patients with spontaneous angina at rest, butnot in other subsets of IHD patients, and establish the possibilityof detecting in vivo platelet activation in IHD by means ofsuch circulating markers.     

The clinical significance of raynaud's phenomenon in systemic lupus erythematosus

In a prospective study of 226 patients with systemic lupus erythematosus (SLE), 91 patients (40%) had Raynaud's phenomenon. These patients were compared to 135 patients without Raynaud's phenomenon. Patients with Raynaud's phenomenon had a greater incidence of arthritis (P < 0.02), malar rash (P < 0.003), and photosensitivity (P < 0.03), and a lesser incidence of severe renal disease as manifested by serum creatinine over 3.0 mg/dl (P < 0.007) or creatinine clearance below 60 ml/minute. Patients with Raynaud's phenomenon were less likely to have severe, life threatening disease and received a lower average monthly (P < 0.01). and a lower peak daily corticosteroid dose (P < 0.01). Fourteen patients (16%) with Raynaud's phenomenon died, compared to 41 without (30%) (P < 0.03). Raynaud's phenomenon in patients with SLE is associated with milder disease and may be regarded as a favorable prognostic sign.     

Time to diagnosis in systemic sclerosis: Is sex a factor?

Objective

To determine whether sex plays a role in the time to diagnosis of systemic sclerosis (SSc).

Methods

In the Canadian Scleroderma Research Group registry, dates of onset of Raynaud's phenomenon, the first non–Raynaud's disease symptom, and diagnosis were recorded based on patient reports. Association between sex and time to diagnosis was assessed for the group as a whole and stratified based on extent of skin involvement, either limited or diffuse.

Results

Of the 408 patients studied (347 women, 61 men, 44% with diffuse cutaneous SSc), the time to diagnosis after the onset of Raynaud's phenomenon was significantly longer for women than men (log rank P = 0.001), but not significantly different after the onset of the first non–Raynaud's disease manifestation. In an analysis stratified by limited or diffuse status, the time to diagnosis from onset of Raynaud's phenomenon was also significantly longer for women than men with diffuse cutaneous SSc (log rank P = 0.008). A trend toward a longer period between onset of Raynaud's phenomenon and SSc diagnosis was observed in women compared with men with limited cutaneous SSc (median 4.6 years in women versus 2.1 years in men; P = 0.085), and there was no sex difference in time to diagnosis after the onset of the first non–Raynaud's disease manifestation.

Conclusion

In SSc, the time to diagnosis is longer for women than men after the onset of Raynaud's phenomenon, suggesting that there may be possible biologic differences in the progression of disease or in the health care trajectories of men and women with early SSc.     

Cold exposure increases cyclic guanosine monophosphate in healthy women but not in women with Raynaud's phenomenon

Abstract. Objective. To investigate influence of whole-body cooling on cyclic GMP (cGMP) in women with Raynaud's phenomenon and in healthy women. Design. The study was performed as an open, parallel-group comparison between women with Raynaud's phenomenon and healthy women during the winter month of February. Setting. The municipality of Västerås (Sweden). Participants. The Raynaud group comprised 24 female patients. The control group consisted of 21 healthy females. Main outcome measure. The venous levels of cGMP were measured on three different occasions: just before and after 40 min of whole-body cooling and after 20 min rest at room temperature (21°C). Results. Venous cGMP increased significantly in the control group after cold exposure (mean difference 0.43 pmol ml^?1; 95% CI, 0.018–0.848; t = 2.18; df = 20; P = 0.02) and remained at a high level after 20 min rest (mean difference 0.58 pmol mL^?1; 95% CI, 0.063–1.108; t = 2.34; df = 20; P = 0.015). In contrast, the levels of venous cGMP in the Raynaud group did not change significantly. The difference in increase between the two groups was significant (P < 0.02). The diastolic blood pressure in the Raynaud group increased after 40 min of whole-body cooling and was still significantly increased (P < 0.001) after 20 min rest at room temperature (21 °C). Conclusion. These results indicate that women suffering from Raynaud's phenomenon lack the physiological response of cGMP to cold exposure, which may explain their increased vasospastic response.     

Supine rest reduces platelet activation and aggregation

Platelet activation and aggregation are central processes in acute coronary syndromes and myocardial infarction, and are stimulated by physical and mental stress. However, it is not known if and to what extent the "ordinary" stress inherent in a person's daily routine contributes to platelet activation and aggregation. We measured platelet activation and aggregation in 12 healthy non-smokers, before and after 45 min supine rest in a calm environment. This simple manouver resulted in a highly significant fall in platelet aggregation (7.9-4.4 ohms, p <0.001) and in plasma epinephrine (35.6-22.5 ng/ml, p = 0.037), norepinephrine (392.8-202.7 ng/ml, p <0.001) and soluble P-selectin (51.9-44.7 ng/ml, p <0.001). Von Willebrand factor (86.2-80.9 IU/ml) and beta-thromboglobulin (279.1-262.4 IU/ml) did not change significantly. Our findings show that a person's ordinary daily routine contributes to platelet activation and aggregation, and that these can be reduced by supine rest. This has methodological implications for studies involving measures of platelet activation and aggregation, and also suggests a mechanism by which bed rest in a calm environment may contribute, however slightly, to the management of acute coronary syndromes.     

Increased plasma beta-thromboglobulin in patients with coronary artery vein graft occlusion: response to low dose aspirin

The therapeutic effect of aspirin on vein graft patency was studied in patients undergoing coronary artery bypass graft surgery. The study design enabled the prospective evaluation of the relation of platelet activation, as measured by plasma beta-thromboglobulin concentration, to subsequent coronary vein graft occlusion. Serial beta-thromboglobulin levels were measured in 105 patients randomized to receive aspirin (324 mg/day) or placebo beginning within 1 h after surgery. Graft patency was assessed angiographically at 1 week and 1 year after surgery. Of 49 patients receiving placebo, 17 (34.7%) had one or more graft occlusions, 6 early, 10 late and 1 with both early and late occlusion. Of 56 patients receiving aspirin, 7 (12.5%) had one or more occlusions, 3 early and 4 late (p less than 0.01). Preoperatively, the beta-thromboglobulin level in surgical patients (29 +/- 13.5 ng/ml) was significantly higher than that of 51 control subjects (22.6 +/- 11.1 ng/ml) (p less than 0.004). Plasma beta-thromboglobulin levels remained comparatively constant at 3 and 12 months after surgery in the 43 patients who had both samples available (p less than 0.001, r = 0.65). The reduction in beta-thromboglobulin concentration from the preoperative level to 12 months postoperatively was greater in the aspirin-treated group (p less than 0.001). Multivariate logistic regression analysis demonstrated a significant association between preoperative beta-thromboglobulin concentration and graft occlusion (p less than 0.02), and aspirin treatment was effective in preventing occlusion when adjusted for the preoperative beta-thromboglobulin level (p less than 0.005). Plasma beta-thromboglobulin concentrations are elevated in patients with coronary artery disease, suggesting ongoing platelet activation.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparative efficacy of nicardipine, a new calcium antagonist, versus nifedipine in effort stable angina

The relative efficacy of nicardipine and nifedipine was examined in a double-blind randomized trial. We studied 12 patients with chronic effort angina who had reproducible chest pain and greater than or equal to 1.5 mm of ST-segment depression on treadmill exercise testing performed before and after 1-week control period of single-blind placebo administration. Subsequently over a 9-week period, nicardipine 20 mg or nifedipine 10 mg or an identical placebo four times a day, was administered in a randomized double-blind crossover fashion. Treadmill exercise testing was performed at the end of each 3-week period. Both nicardipine and nifedipine reduced the frequency of anginal attacks and trinitrate consumption. Compared with placebo both drugs caused a comparable increase of the total duration of exercise (p less than 0.05 placebo versus nicardipine; p less than 0.01 placebo versus nifedipine) and of the time to the onset of angina (p less than 0.05 placebo versus nicardipine; p less than 0.01 placebo versus nifedipine) and to the appearance of 1.5 mm ST depression (p less than 0.05 placebo versus nicardipine; p less than 0.01 placebo versus nifedipine). Moreover 4 patients no longer had angina with either drug and only 1 patient with placebo. Both drugs increased resting heart rate and reduced systolic blood pressure at resting (p less than 0.01) and submaximal exercise (p less than 0.01). Peak heart rate, systolic blood pressure and rate-pressure product were similar with placebo, nicardipine and nifedipine. No important side effects were observed with either drug. We conclude that nicardipine and nifedipine produce similar haemodynamic and clinical effects in patients with stable angina.     

Platelet release of beta-thromboglobulin within the coronary circulation during cold pressor stress

Cold stress by increasing circulating catecholamines may sensitize blood platelets to aggregate and release their constituents. This study investigates the effect of cold stress on the release of the platelet-specific protein beta-thromboglobulin into the coronary venous blood of 12 subjects with atherosclerotic coronary artery disease (CAD) and 7 subjects with angiographically normal coronary arteries (NCA). Cold pressor stress caused a greater increase in systolic arterial pressure in patients with CAD than in subjects with NCA (p less than 0.05). There was no significant difference between the platelet counts in the arterial or coronary venous blood either before or during cold stress. Arterial beta-thromboglobulin was higher in the group with CAD (77 +/- 18 ng/ml) than in subjects with NCA (49 +/- 12 ng/ml, p less than 0.01). Although there was no arteriovenous difference of beta-thromboglobulin at rest in either group, during cold stress, coronary venous beta-thromboglobulin increased in both the NCA (53 +/- 16 to 95 +/- 26 ng/ml, p less than 0.05) and CAD groups (76 +/- 13 to 117 +/- 53 ng/ml, p less than 0.025) despite no change in arterial beta-thromboglobulin. Release of beta-thromboglobulin, although not related to the presence of angiographic arterial disease, correlated with the systolic arterial pressure during cold stress (r = 0.66) and inversely with the platelet's ability to generate cyclic adenosine monophosphate (r = 0.69). The release of platelet constituents in the coronary circulation is provoked by cold stress and may play a role in stress-induced acute coronary occlusion in patients with atherosclerotic disease and in those with apparently normal vessels.