ABSTRACT
Because there are so few data on the long-term effects on left ventricular systolic function and functional status in patients who electively undergo Bentall procedures, we established a retrospective study group of 90 consecutive patients. This group consisted of 71 male and 19 female patients (mean age, 54 ± 10 yr) who had undergone the Bentall procedure to correct aortic valve disease and aneurysm of the ascending aorta, from 1997 through 2003 in a single tertiary-care center. We monitored these patients for a mean period of 117 ± 41 months for death, left ventricular ejection fraction and volume indices, and functional capacity as determined by New York Heart Association (NYHA) class. There were no operative deaths. The survival rate was 73.3% during follow-up. There were 10 cardiac and 13 noncardiac deaths, and 1 death of unknown cause. Echocardiography was performed before the index procedure and again after 117 ± 41 months. In surviving patients, statistically significant improvement in left ventricular ejection fraction, in comparison with preoperative values (0.49 ± 0.11 vs 0.41 ± 0.11; P <0.0001), was noted at follow-up. Similarly, we observed statistically significant reductions in left ventricular end-systolic (39.24 ± 28.7 vs 48.77 ± 28.62 mL/m(2)) and end-diastolic volumes (54.63 ± 6.97 vs 59.17 ± 8.92 mL/m(2); both P <0.0001). Most patients (53/66 [80.3%]) progressed from a higher to a lower NYHA class during the follow-up period. The Bentall procedure significantly improved long-term left ventricular systolic function and functional status in surviving patients who underwent operation on a nonemergency basis.
Subject(s)
Aortic Aneurysm, Thoracic/surgery , Aortic Valve/surgery , Heart Valve Diseases/surgery , Heart Valve Prosthesis Implantation/methods , Heart Ventricles/physiopathology , Vascular Surgical Procedures/methods , Ventricular Function, Left/physiology , Adult , Aged , Aortic Aneurysm, Thoracic/complications , Aortic Aneurysm, Thoracic/diagnosis , Aortic Valve/diagnostic imaging , Echocardiography , Female , Follow-Up Studies , Heart Valve Diseases/complications , Heart Valve Diseases/diagnosis , Heart Ventricles/diagnostic imaging , Humans , Male , Middle Aged , Retrospective Studies , Systole , Time Factors , Treatment OutcomeABSTRACT
BACKGROUND: There is ongoing debate regarding the efficacy of the radial artery (RA) as an aortocoronary conduit, with few solid data regarding long-term clinical results. We sought to determine if the use of the RA as the second arterial conduit, beside left internal thoracic artery (LITA), would improve long-term clinical outcome after CABG as compared to saphenous vein graft (SVG). METHODS: Between March 2001 and November 2003, 200 patients underwent isolated CABG and were randomized in 1:1 fashion to receive either LITA and RA grafts or LITA and SVGs. The primary end point was composite of cardiovascular mortality, non-fatal myocardial infarction and need for repeat myocardial revascularization (either surgical or percutaneous). RESULTS: There was no significant difference in absolute survival, with 12 deaths in each group during the study period (log rank = 0.01, p = 0.979). There were 3 and 2 cardiac deaths in RA and SVG groups, respectively. There was no difference in long-term clinical outcome between the groups (log rank = 0.450, p = 0.509). Eleven patients in RA group had one or more non-fatal events; 7 patients suffered a myocardial infarction, 9 patients underwent percutaneous coronary angioplasty, and 1 patient required redo coronary surgery. Likewise, 13 patients in SVG group had non-fatal event; 7 patients had myocardial infarction, 13 patients had percutaneous coronary intervention and 3 patients required redo coronary surgery. Angiograms were performed in 23 patients in RA group (patency rate 92 %) and 24 in SVG group (patency rate 86 %) (p = 0.67). CONCLUSION: In this small randomised study our data indicate that there is no difference in the 8 year clinical outcomes in relatively young patients between those having a RA or a saphenous vein graft used as a second conduit, beside LITA, for surgical myocardial revascularisation.
Subject(s)
Coronary Artery Bypass/methods , Coronary Artery Disease/surgery , Myocardial Revascularization/methods , Radial Artery/transplantation , Saphenous Vein/transplantation , Aged , Coronary Artery Disease/mortality , Female , Follow-Up Studies , Humans , Male , Mammary Arteries/surgery , Middle Aged , Myocardial Infarction/surgery , Postoperative Complications , Treatment OutcomeABSTRACT
Surgery for acute aortic dissection is challenging, especially in cases of cerebral malperfusion. Should we perform only the aortic repair, or should we also reconstruct the arch vessels when they are severely affected by the disease process? Here we present a case of acute aortic dissection with multiple tears that involved the brachiocephalic artery and caused cerebral and right upper-extremity malperfusion. The patient successfully underwent complete replacement of the brachiocephalic artery and the aortic arch during deep hypothermic circulatory arrest, with antegrade cerebral protection. We have found this technique to be safe and reproducible for use in this group of patients.
Subject(s)
Aorta, Thoracic/surgery , Aortic Aneurysm/surgery , Aortic Dissection/surgery , Blood Vessel Prosthesis Implantation , Plastic Surgery Procedures , Acute Disease , Adult , Aortic Dissection/diagnosis , Aortic Dissection/physiopathology , Aorta, Thoracic/diagnostic imaging , Aorta, Thoracic/physiopathology , Aortic Aneurysm/diagnosis , Aortic Aneurysm/physiopathology , Aortography/methods , Cerebrovascular Circulation , Circulatory Arrest, Deep Hypothermia Induced , Hemodynamics , Humans , Male , Multidetector Computed Tomography , Perfusion , Treatment OutcomeABSTRACT
OBJECTIVE: Surgical closure of patent ductus arteriosus (PDA) is still required in selected adult patients. We analyzed the morphology of the anomaly and coexisting pathological findings in adult patients who were recently referred to our institute for surgical PDA repair. PATIENTS AND INTERVENTIONS: Six adult PDA patients who were not considered candidates for percutaneous closure underwent surgical PDA correction. In three patients with isolated PDA, computed tomographic scan revealed short, wide, and distorted ductus. In the remainder three patients, concomitant heart or aortic disease was found. Transpulmonary approach under total cardiopulmonary bypass or hypothermic circulatory arrest was performed. RESULTS: In all patients, a Dacron patch was used to close the duct. The balloon occlusion technique with normothermic cardiopulmonary bypass was performed in four patients. In one of these patients, the balloon occlusion was not feasible because of unfavorable ductal anatomy, and PDA was closed in short hypothermic circulatory arrest. In two patients with aortic aneurysm, PDA closure and aortic reconstruction were performed in deep hypothermic circulatory arrest. No significant complications occurred during postoperative course. After the mean follow-up period of 48 months, neither ductal reopening nor aneurysmal degeneration of remnant ductal tissue was found. CONCLUSION: Surgical PDA closure in adults remains the treatment of choice in wide, deformed PDAs unsuitable for percutaneous closure and PDAs associated with surgical aortic or heart disease.
Subject(s)
Cardiac Surgical Procedures , Ductus Arteriosus, Patent/surgery , Adult , Age Factors , Cardiopulmonary Bypass , Ductus Arteriosus, Patent/diagnosis , Ductus Arteriosus, Patent/physiopathology , Female , Heart Arrest, Induced , Humans , Hypothermia, Induced , Male , Middle Aged , Serbia , Time Factors , Tomography, X-Ray Computed , Treatment Outcome , Young AdultABSTRACT
BACKGROUND: We and others have shown previously that left ventricular (LV) contractile reserve assessed quantitatively by high-dose dobutamine stress-echocardiography (DSE) has prognostic implications in patients with dilated cardiomyopathy. PURPOSE: To assess the feasibility of semi-quantitative assessment of LV contractile reserve by differently skilled operators in patients with dilated cardiomyopathy. METHODS: High-dose DSE was performed in 63 consecutive patients, mean age 50 ± 10 years and ejection fraction (EF) 19 ± 8%. LVEF was calculated 1) using Simpson's biplane formula, and 2) semi-quantitatively (5% increments) by novice and experienced echocardiographers, and by a DSE expert. Patients were considered to have preserved LV contractile reserve if LVEF dobutamine-induced change was ≥5%. RESULTS: Twenty-seven (45.8%) patients died during the 5-year follow-up. The feasibility of the assessment was 89%, 94%, and 98% for novice and experienced readers and DSE expert, respectively. Kaplan-Meier analysis showed that LV contractile reserve assessed semi-quantitatively by DSE expert and experienced reader achieved the best prognostic separation (log rank 19.63 and 18.99, respectively, p < 0.001 for both), followed by quantitative assessment (log rank 9.76, p = 0.0018) and assessment by novice reader (log rank 8.76, p = 0.012). Areas under the curves were similar for quantitative and semi-quantitative assessment of LV contractile reserve. CONCLUSIONS: Our data indicate that semi-quantitative assessment of LV contractile reserve is feasible by differently skilled operators.
Subject(s)
Cardiomyopathy, Dilated/diagnostic imaging , Echocardiography, Stress , Heart Ventricles/diagnostic imaging , Myocardial Contraction , Ventricular Function, Left , Adult , Cardiomyopathy, Dilated/mortality , Cardiomyopathy, Dilated/physiopathology , Feasibility Studies , Female , Follow-Up Studies , Humans , Kaplan-Meier Estimate , Male , Middle Aged , Prognosis , ROC CurveABSTRACT
OBJECTIVES: There is still a dilemma about best treatment option for patients with severe carotid and coronary artery disease. Reviving of beating heart revascularization technique and using of carotid stenting makes things even more difficult. Discussion about this subject is getting more and more profound. This is analysis of our initial experience with simultaneous carotid and off pump coronary procedures. MATERIALS AND METHODS: This is retrospective analysis of 18 patients operated using this technique in a period from 2001-2003 yrs. Follow up was done by telephone interview. For survivors specially designed questionaire was fulfilled. RESULTS: We operated total number of 18 patients with average age 60,6+/-9.32 years. Carotid recontruction was performed by eversion technique in all patients. Average number of coronary grafts was 2,67+/-0.88. During postoperative period 1 patient (5.55%) had verified perioperative infarction and 1 patient (5.55%) suffered from stroke. Average number of days in hospital was 9.95+/-4.74. During follow up period of 21 months two more patients died from cardiovascular causes. There was no need for repeat coronary angiogram or reintervention on carotid or coronary arteries. CONCLUSION: Simultaneous carotid and coronary operation performed on beating heart is safe and efficent method of treatment for patients with severe concomitant carotid and coronary artery disease.
Subject(s)
Endarterectomy, Carotid , Coronary Artery Bypass, Off-Pump , Female , Humans , Male , Middle AgedABSTRACT
BACKGROUND: Prognostic value of concomitant aprtic regurgitation (AR) in patients operated for severe aortic stenosis (AS) is not clarified. The aim of this study was to prospectively examine the impact of presence and severity of concomitant AR in patients operated for severe AS on long-term functional capacity, left ventricular (LV) function and mortality. METHODS: Study group consisted of 110 consecutive patients operated due to severe AS. The patients were divided into AS group (56 patients with AS without AR or with mild AR) and AS+AR group (54 patients with AS and moderate, severe or very severe AR). Follow-up included clinical examination, six minutes walk test (6MWT) and echocardiography 12 and 104 months after AVR. RESULTS: Patients in AS group had lower LV volume indices throughout the study than patients in AS+AR group. Patients in AS group did not have postoperative decrease in LV volume indices, whereas patients in AS+AR group experienced decrease in LV volume indices at 12 and 104 months. Unlike LV volume indices, LV mass index was significantly lower in both groups after 12 and 104 months as compared to preoperative values. Mean LVEF remained unchanged in both groups throughout the study. NYHA class was improved in both groups at 12 months, but at 104 months remained improved only in patients with AS. On the other hand, distance covered during 6MWT was longer at 104 months as compared to 12 months only in AS+AR group (p = 0,013), but patients in AS group walked longer at 12 months than patients in AS+AR group (p = 0,002). There were 30 deaths during study period, of which 13 (10 due to cardiovascular causes) in AS group and 17 (12 due to cardiovascular causes) in AS+AR group. Kaplan-Meier analysis showed that the survival probability was similar between the groups. Multivariate analysis identified diabetes mellitus (beta 1.78, p = 0.038) and LVEF < 45% (beta 1.92, p = 0.049) as the only independent predictor of long-term mortality. CONCLUSION: Our data indicate that the preoperative presence and severity of concomitant AR has no influence on long-term postoperative outcome, LV function and functional capacity in patients undergoing AVR for severe AS.
Subject(s)
Aortic Valve Insufficiency/complications , Aortic Valve Stenosis/surgery , Heart Valve Prosthesis Implantation/methods , Aortic Valve Insufficiency/diagnosis , Aortic Valve Insufficiency/physiopathology , Aortic Valve Stenosis/complications , Aortic Valve Stenosis/diagnosis , Echocardiography , Exercise Test , Female , Follow-Up Studies , Humans , Male , Middle Aged , Retrospective Studies , Severity of Illness Index , Time Factors , Treatment Outcome , Ventricular Function, Left/physiologyABSTRACT
OBJECTIVES: This study compared the anti-inflammatory effects of methylprednisolone (MP) and atorvastatin and analysed their influences on clinical variables in patients undergoing coronary revascularization. METHODS: Ninety patients with compromised left ventricular ejection fraction (≤30%) undergoing elective coronary surgery were equally randomized to one of three groups: statin group, treatment with atorvastatin (20 mg/day) 3 weeks before surgery; methylprednisolone group, a single shot of methylpredniosolone (10mg/kg); and control group. RESULTS: Postoperative IL-6 was higher in the control group when compared to the methylprednisolone and statin groups (p<0.01). IL-6 was higher in the statin-treated patients (p<0.05 versus methylprednisolone). Administration of methylprednisolone as well as statin treatment increased postoperative cardiac index, left ventricular stroke work index, decreased postoperative atrial fibrilation rate and reduced ICU stay (p<0.05 versus control). The number of patients requiring inotropic support was lower in the methylprednisolone group when compared with the other two groups (p<0.01). Tracheal intubation time was reduced in patients who received methylprednisolone (p<0.01 versus control). CONCLUSIONS: Preoperative administration of either methylprednisolone or atorvastatin reduced pro-inflammatory cytokine release, improved haemodynamics, decreased postoperative atrial fibrilation rate and reduced ICU stay in patients with significantly impaired cardiac function undergoing coronary revascularization. Treatment with methylprednisolone was associated with less inotropic support requirements and reduced mechanical ventilation time.
Subject(s)
Anti-Inflammatory Agents/therapeutic use , Heptanoic Acids/therapeutic use , Hydroxymethylglutaryl-CoA Reductase Inhibitors/therapeutic use , Methylprednisolone/therapeutic use , Pyrroles/therapeutic use , Ventricular Dysfunction, Left/drug therapy , Atorvastatin , Female , Humans , Male , Middle Aged , Treatment OutcomeABSTRACT
INTRODUCTION: We described the first case of oversensing due to electric shock in Serbia, in a 54-year-old man who had implantable cardioverter-defibrillator (ICD). CASE OUTLINE: In July 2002, the patient had acute anteroseptal myocardial infarction and ventricular fibrillation (VF) which was terminated with six defibrillation shocks of 360 J. Coronary angiography revealed 30% stenosis of circumflex artery, the left anterior descending coronary artery was recanalized and the right coronary artery was without stenosis. Left ventricular ejection fraction was 20%. In December 2003, an electrophysiology study was performed and ventricular tachycardia (VT) was induced and terminated with 200 J defibrillation shock. Single chamber ICD Medtronic Gem III VR was implanted in January 2004 and defibrillation threshold was 12 J. The patient was followed up during three years every three months and there were no VT/VF episodes and VT/VF therapies. In December 2007, the patient experienced electric shock through the fork while he was making barbecue on the electric grill. ICD recognized this event in VF zone (oversensing) and delivered defibrillation shock of 18 J. The electrogram of the episode showed ventricular sensing--intrinsic sinus rhythm with electric shock potentials which were misidentified as VF. After charge time of 3.16 seconds, ICD delivered defibrillation shock and sinus rhythm was still present. CONCLUSION: Oversensing of ICD has different aetiology and the most common cause is supraventricular tachyarrhythmia.
Subject(s)
Defibrillators, Implantable/adverse effects , Electric Injuries/etiology , Electrocardiography , Humans , Male , Middle Aged , Ventricular Fibrillation/diagnosis , Ventricular Fibrillation/therapyABSTRACT
The administration of glucose-insulin-potassium (GIK) solution has beeen shown to exert cardioprotective and immunomodulatory properties in coronary disease. 49 patients (pts.) for coronary surgery were randomly assigned to receive high-dose GIK treatment (30% glucose, insulin 2 IU.kg(-1).l(-1) and K(+) 80 mmo/l solution; 1 ml/kg/h); low-dose GIK treatment (10% glucose, insulin 32 IU l(-1) and K(+) 80 mmol/l solution; 1 ml/kg/h) or control treatment (Ringer solution 1 ml/kg/h). Haemodynamic measurements were done for four time points: T1 - after induction of anaesthesia; T2 - after the operation; T3 - 6 h after the operation and T4 - 24 h after the operation. Significant recovery of cardiac function was evident in high-dose GIK (H-GIK) and low-dose GIK (L-GIK) groups after 24 h (cardiac index improved considerably (p = 0.0002)), with a statistically significant difference between the groups (p = 0.005). LVSWI covariated with PCWP, improved over time in group H-GIK (p = 0.0008) and between the groups (p = 0.046). Oxygen supply-consumption ratio evidently improved in the GIK groups, while inotropic drug support was used in 5.5% pts. in group H-GIK vs. 13% in group L-GIK and 31% pts. in control (C) group. Glucose-insulin treatment has a potential cardioprotective effect in coronary surgery. The effect is independent of the glucose-insulin concentration and amount.
Subject(s)
Glucose/pharmacology , Heart/physiopathology , Insulin/pharmacology , Ischemic Preconditioning, Myocardial/methods , Potassium/pharmacology , Recovery of Function/drug effects , Thoracic Surgery , Coronary Disease/metabolism , Coronary Disease/physiopathology , Coronary Disease/surgery , Coronary Disease/therapy , Dose-Response Relationship, Drug , Echocardiography , Female , Heart/drug effects , Hemodynamics/drug effects , Humans , Intraoperative Period , Male , Middle Aged , Oxygen/metabolism , Postoperative Period , SolutionsABSTRACT
The residual aortic prosthetic valve paravalvular space beneath the left coronary artery is very difficult and risky to repair. To improve visualization of this area, we transected the ascending aorta and mobilized both the aortic root and the left coronary artery from the surrounding tissue. Subsequently, we retracted the left coronary artery aside and pulled the posterior aortic root upwards. This maneuver has provided enough space for the safe placement of stitches and the closure of the paraprosthetic defect in this very delicate area.
Subject(s)
Aorta, Thoracic/surgery , Bioprosthesis , Heart Valve Diseases/surgery , Heart Valve Prosthesis Implantation/methods , Suture Techniques , Aortic Valve/microbiology , Aortic Valve/surgery , Echocardiography, Transesophageal , Endocarditis, Bacterial/complications , Female , Follow-Up Studies , Heart Valve Diseases/diagnostic imaging , Heart Valve Diseases/etiology , Humans , Middle Aged , Mitral Valve/microbiology , Mitral Valve/surgery , Prosthesis Fitting/methods , Risk Assessment , Treatment OutcomeABSTRACT
Patient was admitted for endarterectomy of the left internal carotid artery. Echocardiography showed mitral stenosis with mitral valve area of 1.4 cm2. Since the patient's functional capacity could not be determined due to left-sided hemiplegia, it was decided to perform high-dose dobutamine stress-echocardiography in order to assess the patient's hemodynamics during stress. Gradients over mitral valve increased from 32/10 mmHg at baseline to 43/16 mmHg at 40 mcg/kg/min dobutamine infusion. Preoperative and 24 hour perioperative hemodynamic variables were monitored by Swan-Ganz catheter, and their values did not change significantly as compared to baseline. Postoperative course was uneventful, and the patient was discharged on the fifth postoperative day.
Subject(s)
Carotid Stenosis/surgery , Echocardiography, Stress/methods , Mitral Valve Stenosis/diagnostic imaging , Perioperative Care/methods , Aged , Blood Pressure , Cardiac Output , Carotid Artery, Internal , Carotid Stenosis/complications , Carotid Stenosis/physiopathology , Endarterectomy, Carotid , Heart Rate , Humans , Male , Mitral Valve Stenosis/complications , Mitral Valve Stenosis/physiopathology , Treatment Outcome , Vascular ResistanceABSTRACT
Resveratrol, a stilbene polyphenol found in grapes and red wine, produces vasorelaxation in both endothelium-dependent and endothelium-independent manners. The mechanisms by which resveratrol causes vasodilatation are uncertain. The aim of this study was to investigate the mechanism(s) of endothelium-independent resveratrol-induced vasorelaxation in human internal mammary artery (HIMA) obtained from male patients undergoing coronary artery bypass surgery and to clarify the contribution of different K+ channel subtypes in resveratrol action in this blood vessel. HIMA rings without endothelium were precontracted with phenylephrine. Resveratrol induced a concentration-dependent relaxation of the HIMA. A highly selective blocker of ATP-sensitive K+ channels, glibenclamide, as well as nonselective blockers of Ca2+-sensitive K+ channels, tetraethylammonium and charybdotoxin, did not block resveratrol induced relaxation of HIMA rings. 4-Aminopyridine (4-AP), non selective blocker of voltage gated K+ (KV) channels, and margatoxin that inhibits KV1.2, KV1.3, and KV1.6 channels abolished relaxation of HIMA rings induced by resveratrol. In conclusion, we have shown that resveratrol potently relaxed HIMA rings with denuded endothelium. It seems that 4-AP- and margatoxin-sensitive K+ channels located in smooth muscle of HIMA mediated this relaxation.
Subject(s)
Mammary Arteries/drug effects , Muscle, Smooth, Vascular/drug effects , Stilbenes/pharmacology , Vasodilator Agents/pharmacology , Wine , 4-Aminopyridine/pharmacology , Anti-Arrhythmia Agents/pharmacology , Charybdotoxin/pharmacology , Coronary Artery Bypass , Coronary Disease/surgery , Glyburide/pharmacology , Humans , Male , Mammary Arteries/metabolism , Middle Aged , Muscle Relaxation/drug effects , Muscle, Smooth, Vascular/metabolism , Neurotoxins/pharmacology , Potassium Channel Blockers/pharmacology , Potassium Channels/metabolism , Resveratrol , Scorpion Venoms/pharmacology , Tetraethylammonium/pharmacology , Vasodilation/drug effectsABSTRACT
A patient presented with severe triple-vessel coronary artery disease, including multiple lesions on the left anterior descending coronary artery (LAD), which supplied a well-contracting myocardium. In approaching our patient, we judged that a pedicled left internal thoracic artery (LITA) would not provide enough length for sequential grafting of the multisegment-diseased LAD. We also considered that a pedicled right internal thoracic artery (RITA) conduit would not be long enough to provide a free segment that would form a tandem graft with a LITA and then arrive at the marginal branch, unless it was detached at its origin. Consequently, we decided to form a composite graft that would connect a free, short segment (6-7 cm) of pedicled LITA to the in situ pedicled RITA, in an end-to-end fashion. This new composite conduit enabled us to perform sequential grafting (3 sequential anastomoses, 2 with the LITA segment) of the multisegment-diseased LAD, following the route anterior to the aorta. The in situ remnant of the LITA was grafted to the marginal branch. Although many large series have reported resourceful solutions, to the best of our knowledge, tandem arterial sequential grafting (an in situ pedicled RITA plus a free, short segment of a pedicled LITA) has not heretofore been reported in application to the multisegmented-diseased LAD artery. We strongly believe that this technique is an attractive variation on bilateral pedicled ITA left-sided revascularization in cases of multivessel coronary artery disease, including LADs with multiple lesions.
Subject(s)
Coronary Artery Bypass , Coronary Artery Disease/surgery , Coronary Angiography , Coronary Artery Bypass/methods , Coronary Vessels/surgery , Humans , Male , Middle Aged , Severity of Illness Index , Thoracic Arteries/surgeryABSTRACT
It is well established that spasm of an arterial and venous graft conduit may occur during harvesting or after coronary artery bypass grafting (CABG). The antivasoconstrictor effect of levcromakalim and rilmakalim, K(+) channel openers (KCOs), was studied in isolated human internal mammary artery (HIMA) and human saphenous vein (HSV) prepared for CABG. HIMA and HSV rings were contracted by electrical field stimulation (EFS, 20 Hz ) or with exogenous noradrenaline (NA). Levcromakalim induced a concentration-dependent and equipotent inhibition of contraction of HIMA and HSV preconstricted by EFS and exogenoulsy applied NA, while rilmakalim produced a stronger inhibition of EFS- than NA-evoked contractions. Glibenclamide, a selective ATP-sensitive K(+) channel (K(ATP) channel) blocker, significantly antagonized levcromakalim-induced inhibition of EFS- and NA-evoked contractions, as well as rilmakalim-induced inhibiton of EFS-evoked contractions on HIMA and HSV. However, glibenclamide failed to antagonize rilmakalim-induced inhibition of NA-evoked contractions. The results suggest that the antivasoconstrictor effect of levcromakalim occurs postsynapticaly by the opening K(ATP) channels in the vascular smooth muscle cells. They also suggest that the effect of rilmakalim on EFS-evoked contractions involves K(ATP) channels located pre-synaptically. However, the mechanism by which rilmakalim inhibits NA-evoked contraction seems to be K(ATP) channel independent and warrants further elucidation.