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At present, transcatheter aortic valve implantation (TAVI) is a proven treatment option for patients with symptomatic degenerative aortic stenosis at high risk for conventional surgery. In countries where TAVI is currently performed, the number of procedures and centers involved has been continuously increasing. The present document from the Italian Society of Interventional Cardiology (SICI-GISE) aims to improve the available evidence and current consensus on this topic through the definition of training needs and knowledge base for both operators and centers.

Background: The organization of a regional system of care (RSC) for ST-elevation myocardial infarction (STEMI) is recommended by the Italian Federation of Cardiology (FIC) and international guidelines in order to increase the number of patients treated with primary coronary angioplasty and, more in general, with reperfusion therapy, speed up the diagnostic and therapeutic processes, and ultimately improve the outcome., Methods: The "RETE IMA WEB" survey was launched in 2007 from the Italian Society of Invasive Cardiology (SICI-GISE) in collaboration with the FIC, with the aim of evaluating the current state of RSC for STEMI in Italy. The personnel of the 118 Emergency System participated in the survey. Data collection was made using different electronic forms with access limited by personal passwords. We assessed the organization of the RSC together with local resource availability, with specific attention to the distance from a Hub center., Results: The survey ended in December 31, 2008. We censored 701 hospitals admitting STEMI patients, 157 (22.4%) with uninterrupted access (h24/7 days) to the catheterization laboratory (2.67 per million inhabitants). An operative network was present in 36/103 (35.9%) provinces, with important geographic variability. Among hospitals without a full-time primary angioplasty facility, only 46% was within a RSC. ECG was available in 72% of the national territory, telemedicine in 50%. Prehospital fibrinolysis was available in 16% of the country. Overall, 92.4% of the Italian population resides within 60 min of a Hub center., Conclusions: In 2008, despite an adequate framework, the RSC for STEMI in Italy was heterogeneous and still suboptimal. Healthcare administrators, scientific societies and all operators involved in the process of care for STEMI should make efforts to implement current guidelines.

Background: Primary percutaneous coronary intervention (pPCI) is the most effective reperfusion treatment of acute ST-segment elevation myocardial infarction (STEMI), but logistic- and organization-related problems affect its feasibility. The aim of this study was to investigate a) the requirements of reperfusion therapies, and b) the feasibility of pPCI as suggested by the current guidelines, in the Veneto Region., Methods: With the aim to treat with pPCI most of the patients with high-risk STEMI regardless of the type of admitting hospital, a single treatment protocol was developed and shared by the majority of Cardiology Departments in the Veneto Region. Data of all consecutive patients with STEMI were prospectively recorded and subsequently and independently compared with administrative data., Results: In 28 participating hospitals, 1160 consecutive patients with STEMI were enrolled during a 6-month period: in 999 symptom onset was < 12 hours. Based on the registry data, it is possible to estimate that 697 patients/million of inhabitants/year are admitted in Cardiology Departments with the initial diagnosis of STEMI: 86% are admitted < 12 hours from symptom onset and 58% of them have at least one characteristic of high risk. The strategy of immediate coronary angiography and possible PCI was carried out in 52.3% of eligible patients: in 55.8 and 47.5% of high- and low-risk STEMI and from 17.1 to 75.1% based on the type of admitting hospital. Recanalization with pPCI was obtained < 90 min from the diagnosis in 70 and 32% of patients treated on site and transferred, respectively., Conclusions: The absolute number of patients with STEMI eligible for reperfusion therapies is lower than previously reported. The reperfusion strategy based on pPCI was much more related to the type of admitting hospital than to the clinical characteristics of the patients. pPCI performed as suggested by the current guidelines is feasible in patients admitted in hospitals with interventional facilities available 24 hours/day, but in those who need to be transferred it is necessary to modify the existing pathways and/or treatment protocols.

We describe a case of a 54-year-old woman with a history of palpitations due to recurrent atrial fibrillation. The diagnosis of a coronary artery fistula between the right coronary artery and right atrium was made after the detection of a continuous cardiac murmur. In view of the patient symptoms and owing to the aneurysmatic dilation of the fistula, she was submitted to percutaneous closure. The anatomic features of the fistula and the closure device used demonstrate the peculiarity of the intervention. An artery-venous loop crossing the coronary fistula was created via the femoral vein and artery; the Amplatzer duct occluder was then advanced through this loop up to the fistula neck and successfully delivered. At 1-month follow-up the patient was totally asymptomatic. Cardiac auscultation revealed that the murmur was no longer detectable. Current guidelines for the treatment of coronary fistulas and on their percutaneous closure are discussed.

A patient with symptomatic pliable mitral stenosis and a significant lesion of the left coronary artery underwent combined interventional procedures during a single session. From the femoral approach a percutaneous transluminal coronary angioplasty was performed, with unsatisfactory results and necessitating stent implantation. Thereafter, mitral valve stenosis was relieved by percutaneous balloon valvotomy.

Normal gestation is associated with adaptative cardiovascular changes. Pregnant women with mitral stenosis may be unable to tolerate these changes despite optimal medical therapy, and life-threatening complications can occur. Commissurotomy or valve replacement during gestation are very high-risk procedures both for mother and fetus. Percutaneous valvuloplasty is a valid alternative to cardiac surgery. In this study, we describe four pregnant women with mild or severe mitral stenosis who underwent percutaneous valvuloplasty after the first trimester of gestation. Despite tailored medical therapy with diuretics and beta blockers, all patients were symptomatic: NYHA class II in two cases, and class III in the last two. In order to protect the fetus from radiation, the patient's pelvic-abdominal area was shielded and left ventriculography was not performed. Fluoroscopy time was 7 +/- 3 min. No major immediate complications were observed after the procedure. Mitral valve area (sec. Gorlin) increased from 1.05 +/- 0.08 cm2 to 2.52 +/- 0.26 cm2 and mitral gradient decreased from 26.7 +/- 5.7 mmHg to 8.5 +/- 3 mmHg. The four women delivered healthy full-term babies. At a mean follow-up of 22 +/- 8 months, all patients are free of symptoms, two patients with diuretics and two without therapy. Percutaneous valvuloplasty can be considered the treatment of choice for pregnant women with symptomatic mitral stenosis refractory to medical therapy.

Percutaneous balloon valvuloplasty is used successfully for mitral and aortic rheumatic stenosis. Its application is limited in elderly degenerative aortic stenosis because of its poor long-term results. It is thus indicated only in selected groups of patients at high surgical risk. We describe three cases affected with mitral and aortic stenosis who underwent simultaneous mitral and aortic percutaneous balloon valvuloplasty. Etiology was rheumatic in the first two cases, while it was rheumatic and degenerative in the third case. Immediately after the procedure, mitral and aortic gradients decreased, with a simultaneous increment in aortic and mitral areas and cardiac index. There were no major complications. The follow-up after seven years revealed the persistence of relatively good results in the first two cases affected with rheumatic valvulopathies. In the last case, restenosis recurred a few years after the procedure.

Patients with recurrent angina after coronary artery bypass graft surgery pose a problem. Stent implantation has been advocated in an effort to avoid repeat operation and to address the limitations of balloon angioplasty. Aim of the present study was to determine the in-hospital and long-term results of stent deployment in focal, de novo lesions of vein grafts. Thirty-five focal, de novo lesions of vein grafts in 31 patients were treated with stent deployment. Twenty-four patients (77%) had three vessels, 6 (20%) two vessels and 1 (3%) single vessel disease. Saphenous vein grafts aged 9.7 +/- 4.2 years (range 1-19 years). Twenty-two lesions (63%) were located within the body of the saphenous graft, 8 (23%) at the graft/coronary artery anastomosis and 5 (14%) at the aorta/graft anastomosis. The indications for stent deployment included: suboptimal result from balloon angioplasty (defined as > or = 50% post-angioplasty residual stenosis) in 29/35 lesions (83%); post-angioplasty coronary dissection with threatening occlusion in 4/35 (11%); abrupt closure in 2/35 (6%). Patients were screened for death, myocardial infarction, bypass surgery and repeat angioplasty during in-hospital stay and after a follow-up of 12 +/- 8 months. Even-free survival curve was constructed by the Kaplan-Meier method. Stent deployment was successful in all patients. One stent was deployed in 24/35 lesions (69%), half Palmaz-Schatz stent in 6/35 (17%) and 2 or more stents in 5/35 (14%). The balloon/vessel ratio resulted of 1.0 +/- 0.1 Minimal lumen diameter increased from 0.8 +/- 0.4 to 3.8 +/- 0.6 mm, with a mean gain of 1.8 +/- 0.6 mm (range 1.8-4.0 mm). During the in-hospital period 1 patient (3.2%) died and 1 (3.2%) had a non Q wave myocardial infarction. Therefore, the clinical success rate, was 94%. During the follow-up period, 2 patients died (6.9%), 2 (6.9%) developed a non Q wave myocardial infarction, 1 (3.4%) underwent bypass surgery and 3 (10.3%) underwent repeat angioplasty. The estimated 2-year event-free survival rate (free from myocardial infarction, repeat surgery and repeat angioplasty) was 62%. In conclusion, Palmaz-Schatz stent deployment in focal, de novo vein grafts presents a high rate of procedural success, a low rate of acute complications and good long-term results.

Primary percutaneous transluminal coronary angioplasty (PTCA) for acute myocardial infarction (AMI) allows to obtain a higher reperfusion rate in the culprit vessel than thrombolytic therapy, reducing the incidence of death, non fatal reinfarction and recurrent ischemia. The aim of this study was to test the in-hospital and mid-term results of an early invasive strategy with PTCA in patients with AMI. Thirty-four patients with AMI underwent coronary angiography within 3 hours from the onset of symptoms. Twenty-four patients had anterior AMI and 3 were in cardiogenic shock. Three patients, 1 without significant lesions and 2 with multivessel diffuse coronary disease, were left out of the procedure, and 31 patients underwent PTCA. Twenty-six lesions were total occlusions with TIMI flow 0.A TIMI flow 1 was present in the other 5 vessels. Stent deployment was decided for 16 lesions (52%). Primary success (TIMI flow 3 with mean residual stenosis of 15 +/- 20%) was obtained in 30 patients (97%). In 1 patient recanalization of the anterior descending coronary artery was not possible due to tortuosity of the abdominal and thoracic aorta. At pre-discharge angiography a good result was confirmed in 24/25 patients. After 6 months only 1 patient (3%) underwent a new PTCA for recurrent angina. In conclusion, primary PTCA for AMI within 3 hours of symptom onset allows good in-hospital and mid-term results with a low rate of complications.

Unlabelled: The frequency of mitral restenosis after surgical commissurotomy has been estimated between 10 and 30% up to 10 years and 85% up to 28 years. Aim of this study was to analyze the results of balloon mitral valvuloplasty (BMV) in a series of patients with previous surgical commissurotomy., Methods: Between December 1988 and December 1995 432 patients underwent BMV. Of these patients, 30 (6.9%; 10 men, 20 women, aged 53 +/- 12 years) had recurrent mitral stenosis after surgical commissurotomy. Contraindications to BMV were the evidence of left atrial thrombi at transesophageal echocardiography and/or of mitral insufficiency > 2+/4+. The Inoue's single balloon catheter was used for all the procedures., Results: BMV resulted in a decrease in mean mitral gradient from 12.6 +/- 3.8 to 6.1 +/- 2.9 mmHg, and an increase in mitral valve area from 1.03 +/- 0.19 cm2 to 1.95 +/- 0.40 cm2. A mitral insufficiency > or = 3+/4+ occurred in 4/30 BMV (13%). At follow-up (mean 27 +/- 18 months) 20/26 patients (77%) remained clinically improved: 54% were in NYHA class I and 23% in class II., Conclusions: BMV is an effective short- and long-term procedure for patients with previous surgical commissurotomy, with a low additional risk of complications. Thus, BMV can be considered the treatment of choice in these patients.

Background: Percutaneous transluminal coronary angioplasty (PTCA) in complex coronary lesions (type B2 and C of the modified AHA/ACC classification) presents a lower primary success rate and higher risk of dissection than type A and B1 lesions. An alternative approach to this lesions is coronary rotational ablation (Rotablator, Heart Technology) with complementary PTCA using low inflation pressures ("facilitated angioplasty")., Materials and Methods: Twenty-six type B2 and C lesions in 24 patients (pts) (8 female, 16 male, age 37-80 years) were treated with coronary rotational ablation and complementary PTCA between January 1993 and December 1994 (4.7% of all interventional coronary procedures performed in this period in our laboratory). Eleven pts had stable effort angina and 13 pts had unstable, class IB, IIB, and IIC, angina. The treated vessel was the LAD in 15 cases, CX in 5, RCA in 5, and an intermediate branch in one case. Coronary rotational ablation was proposed because of the presence of two or more risk factors for uneffective or complicated PTCA: eccentricity, calcified lesions, bifurcation stenosis, lesion length > 10 mm, severe stenosis (90-99%), ostial location and bend location (45-60 degrees). No lesion showed coronary thrombus, considered as absolute contraindication to coronary rotational ablation. We used small burrs (burr/artery ratio < 0.75), and complementary PTCA was performed using low inflation pressure (< 8 atm) and long balloons for long lesions (> 10 mm) in order to minimize the risk of dissection., Results: Coronary rotational ablation was successfully performed in all but two cases (24/26; 92.3%), with a reduction of the stenosis from 88 +/- 9% to 45 +/- 10% (range 30-60%). In two pts (7.7%) the procedure was complicated by acute occlusion: both pts underwent effective salvage PTCA with 30% residual stenosis. Small type A and B dissections occurred in 4/26 cases (15.4%). All but one lesions complicated by acute occlusion or dissection following coronary rotational ablation were not or only slightly calcified. Complementary PTCA was performed in all but two pts who already presented 30% residual stenosis after rotational ablation. A further reduction of stenosis to 20 +/- 9% (range 5-30%) was achieved. After complementary PTCA four pts (15.4%) developed type A and B dissections; in one of these a Palmaz-Schatz stent was implanted, whereas the remaining three pts presented a residual stenosis below 30% and no further procedures were undertaken. Overall success rate of rotational atherectomy plus salvage or complementary PTCA or stenting was 100%, and no major complications (Q-wave myocardial infarction, emergency bypass surgery or death) occurred. Three pts showed delayed coronary run-off (slow reflow) after rotational ablation, and two of these released a small amount of cardiac specific enzymes (CK MB) without ECG changes and wall motion alteration on echocardiographic examination. Clinical restenosis, defined as recurrent angina and/or positive exercise stress test, developed in 45.8% (11 pts); in all these pts restenosis was angiographically evidenced (75-99%)., Conclusions: Our experience suggests that coronary rotational ablation along with complementary PTCA using low inflation pressure and long balloons is safe and effective in type B2 and C lesions if calcifications are present; however, restenosis rate remains high.

Background: Between December 1988 and December 1992, 235 patients (pts) underwent percutaneous balloon mitral valvuloplasty (PBMV)., Methods and Results: There were 55 men (23%) aged 49 +/- 13 years and 180 women (77%) aged 51 +/- 13 years. Previous surgical commissurotomy (PSC) had been performed in 22 pts. Procedure was successful (area > 1.5 cm2 or area increase > or = 50% without mitral regurgitation > 2+) in 91.9% of pts, with increase in mitral valve area from 1.05 +/- 0.2 to 2.26 +/- 0.6 cm2, decrease of transvalvular mean pressure gradient from 14.4 +/- 5.5 to 6.05 +/- 4.91 mm Hg and increase of cardiac index from 2.79 +/- 0.75 to 3.17 +/- 0.9 l/m'/m2 (p < 0.001). Insufficient increase in valve area occurred in 3.8% of pts. Major complications included 5 pts with 3+ mitral regulation (MR) requiring mitral valve replacement (MVR), 2 TIA's (0.85%) and 1 pericardiocentesis (0.42%). At follow-up (mean 18.9 months) clinical improvement was achieved in 93.8% of pts (NYHA class from 2.4 to 1.3); mitral valve area was 1.9 +/- 0.4 cm2 and mean mitral valve gradient 5.3 +/- 2.3 mm Hg. Restenosis (area < 1.5 cm2 or > or = 50% loss of initial gain) occurred in 24 pts (10.16%). Six pts required MVR; 1 pt underwent a second successful PBMV. Multivariate study (logistic regression) identified as independent factors of severe MR NYHA class and PSC; echo score, age and basal mean mitral valve gradient were independent factors for restenosis., Conclusions: In conclusion, PBMV is a safe technique and stable clinical improvement can be obtained in the majority of pts.

Background: Reversibility of pulmonary hypertension in patients affected by mitral stenosis is still under question., Methods: We selected 80 patients (mean age 48 +/- 14) who underwent successful percutaneous mitral valvuloplasty (PMV) for hemodynamic significant mitral stenosis (area < 1.5 cm2) with pulmonary hypertension (mean artery pulmonary pressure--PPM > 25 mm Hg), producing significant increase in mitral valve area (area before PMV = 0.99 +/- 0.23 cm2 vs 2.08 +/- 0.32 cm2 after PMV--p < 0.001) without hemodynamic complications (mitral insufficiency and/or interatrial shunt). Cardiac index, pulmonary arterial pressures, and pulmonary arteriolar resistances were invasively evaluated before and immediately after valvuloplasty. Systolic pulmonary pressure was indirectly monitored by Doppler method in a period from 1 to 3 months after percutaneous mitral valvuloplasty., Results: In general (70 pts.) there was an immediate significant reduction of pulmonary pressure after percutaneous mitral valvuloplasty (mean pulmonary pressure before PMV was 33.9 +/- 7.9 mm Hg vs 26.8 +/- 9.5 mm Hg after PMV, p < 0.01; systolic pulmonary pressure before PMV was 51.5 +/- 10.9 mm Hg vs 43.15 +/- 13.5 mm Hg after PMV--p < 0.01). A small subgroup of 10 pts., older in age (mean 59 +/- 15), manifested no reduction of pulmonary pressure immediately after procedure (mean pulmonary pressure before PMV = 35.2 +/- 8.37 mm Hg vs 36.5 +/- 6 mm Hg after PMV, p: ns; systolic pulmonary pressure before PMV = 58.2 +/- 10.6 mm Hg vs 59.2 +/- 9.6 mm Hg. after PMV, p: ns) and 4 of them (mean age 65 +/- 15) persisting pulmonary hypertension at 1-3 months follow-up (systolic pulmonary pressure before PMV = 58.75 +/- 14 mm Hg, immediately after PMV = 57.8 +/- 12.5 mm Hg, and 1-3 months after PMV = 62.5 +/- 9 mm Hg--p: ns)., Conclusions: Neither severe pulmonary hypertension, nor pulmonary arteriolar resistances but only age seems to be a predictive factor of persisting pulmonary hypertension after percutaneous mitral valvuloplasty in mitral stenosis.

The coronary arteries from the hearts of 7 patients, 6 male and 1 female, age ranging from 39 to 69 years (mean 56), who died early or in the mid term from percutaneous transluminal coronary angioplasty (PTCA), were investigated by histology, immunohistochemistry and electron microscopy. Atherosclerotic coronary artery disease was present in all: single vessel disease in 2 and double vessel disease in 5. Indication to PTCA was stable angina in 1 patient, unstable angina in 2, postinfarction angina in 2 and acute myocardial infarction in the remaining 2. Thrombolysis was an associated procedure in 3 cases. Time interval between PTCA and death was less than 48 hours in 6, and 4 months in 1. Cause of death was myocardial infarction due to coronary occlusion complicating PTCA in 3 patients, and myocardial infarctions preceding PTCA in 4 patients. 9 coronary segments underwent dilatation: 5 in the anterior descending coronary artery, 3 in the right coronary artery and 1 in the left circumflex artery. Angiographically, the PTCA had been effective (decrease of stenosis > or = 40%) in 5 and failed in 4. Basically, the atherosclerotic plaques were eccentric in 3 and concentric in 6; the histotype was fibrotic in 4, atheromatous in 4 and fibro-atheromatous in 1. Only one case did not show any complication and the dilatation was effective as a consequence of plaque compression and stretching of the underlying tunica media. Complications observed in the other cases with early death consisted of: a) plaque cracks with intimal flaps and hematomas in all 6; b) laceration of the tunica media, even of the disease-free wall, with dissecting hematoma in 2; c) occlusive thrombosis in 3 and d) atheroembolism in 1. The 4 coronary segments, which appeared occluded angiographically soon after PTCA, were clinically interpreted as dissection in 3 and thrombosis in 1, whereas at histology the closing mechanism was an intimal hematoma with flap in 2, occlusive thrombosis in 1, and medio-adventitial dissecting hematoma with thrombosis in 1. Only ruptures of atheromatous plaques were complicated by thrombosis. The patient who died at 4 months exhibited a pattern of restenosis due to intimal smooth muscle cell proliferation. In conclusion, our postmortem study shows that PTCA may be associated with severe damage of the coronary artery consisting of plaque crack and laceration even of the disease-free wall, intimal and medial hematomas, thrombosis and atheroembolism.(ABSTRACT TRUNCATED AT 400 WORDS)

Single-vessel coronary disease has been considered so far a benign condition, for which the medical therapy may represent the optimal treatment. In order to assess the effectiveness of this approach, we studied 323 patients who had come to our attention for ischemic heart disease and resulted affected by single-vessel coronary artery disease. From our data it appears that single-vessel coronary artery disease is frequently associated with myocardial infarction and post-infarction aneurysm. Coronary angiography indicated that left anterior descending coronary artery is the most frequently affected vessel, and that its involvement is often associated with lethal outcome. Forty-two out of the 323 patients underwent coronary artery bypass surgery; the remaining patients were medically treated. Surgical patients showed a better improvement respect to the medical group, while survival was not statistically different. An unexpected result was the relatively high risk in circumflex artery lesion. These data may justify a broader utilization of invasive therapy in recent onset angina, in light of the excellent results recently obtained with percutaneous transluminal coronary angioplasty.

The aim of this study was to state whether in patients with dilated cardiomyopathy indices of left ventricular function (i.e. left ventricular end-diastolic and end-systolic volumes, ejection fraction, end-systolic pressure to end-systolic volume ratio, mass to volume ratio, elastic stiffness constant) are related to histologic findings, namely percentage of myocytes, of fibrosis and of interstitium. We have studied 26 patients (18 males and 8 females) aged 13-65 years, who underwent right and left heart catheterization, quantitative angiography, coronary angiogram, and in whom a diagnosis of dilated cardiomyopathy was established. All of them had a biopsy specimen taken from the right aspect of interventricular septum, following the technique of King's College. Histology was automatically evaluated with a computerized system for the percent content of myocytes, of fibrous tissue and interstitium. Correlation with hemodynamic parameters was calculated with the least square method. A significant correlation was found between percentage of fibrosis, left and right ventricular ejection fraction and preload index, and between percent myocytes and right ventricular ejection fraction and duration of disease. Thus, left ventricular function indices do not correlate with percent myocytes, as previously shown: this could be due to the fact that alterations in contractile machinery are due primarily to alterations in cell biochemistry. Moreover, the inverse relationship between myocyte content and duration of the disease may reflect those mechanisms, which tend to perpetuate failure in a dilated heart by increasing subendocardial fibrosis. However, the correlation found between myocyte content and right ventricular ejection fraction may be due to the fact that biopsy specimens were taken from the right ventricle.

In order to evaluate the short and mid-term results of percutaneous aortic balloon valvuloplasty, 40 consecutive elderly patients with symptomatic severe calcific aortic stenosis, underwent the procedure consecutively, with follow-up by clinical evaluation and Doppler echocardiography. Over a mean follow-up period of 11.2 months there were 5 deaths, and 12 patients underwent subsequent aortic valve replacement. Doppler echocardiography revealed an increase in aortic valve area from 0.62 +/- 0.20 cm2 to 0.91 +/- 0.23 cm2 after the procedure, but there was a significant trend toward restenosis by 12 months follow-up in 23 of 32 patients (72%). Restenosis was accompanied by symptomatic deterioration in 18 of 23 patients (78%). Although balloon valvuloplasty may often improve haemodynamics and relieve symptoms, these benefits seem to be short-lived in most cases. Restenosis has a high rate of occurrence. Aortic balloon valvuloplasty should be reserved for truly inoperable cases and for haemodynamically-unstable patients, who may later undergo surgery.

60 patients with clinical signs of coronary artery disease who had a hemodynamic examination were studied. The study of the regional dynamics using the deformation as a vectorial time-dependent parameter and the pressure-length loops, was carried out on a total of 420 parietal regions of the left ventricle: the basal ventriculography, the post-extrasystolic potentiation and the ventriculography after nitroglycerin were evaluated. The dynamic regional pattern was correlated with clinical-enzimatic signs of necrosis in the electrocardiogram. The possibility of correlating signs of necrosis with particular patterns of hypokinesia, akinesia, dyskinesia which differ from corresponding "static" forms of asynergy in active pressure development and deformation (even in a brief systolic interval) seems to confirm the physiopathologic interpretation of the regional phenomenon based on the ratio between viable not viable myocardium -- as primary cause.