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Background: Acute myocardial ischemia and the mode of ventricular fibrillation (VF) induction influence the ventricular defibrillation threshold (DFT)., Objectives: The purpose of this study was to determine the effects of transient regional left ventricular (LV) ischemia on the DFT., Methods: Ventricular effective refractory period (ERP), ventricular fibrillation threshold (VFT), and DFT were measured under nonischemic conditions (control) in 26 pigs weighing 25-35 kg. Myocardial ischemia was then induced by occlusion of the mid left anterior descending coronary artery, and measurements of ERP and VFT were repeated after 2 minutes of occlusion. The coronary artery ligation was released immediately after the onset of VF and DFT was measured., Results: LV ERP was unchanged by ischemia (199 +/- 19 ms at control vs. 200 +/- 22 ms under ischemic conditions, P = 0.799), whereas VFT was significantly lower during coronary occlusion (10.7 +/- 5.4 mA vs. 37.7 +/- 13 mA, P = 0.000). Brief myocardial ischemia caused a significant increase in DFT (13.5 +/- 12.6 J after coronary occlusion vs. 6.8 +/- 6.8 J at control, P = 0.023). The duration of coronary occlusion was not correlated with the amounts of energy required to defibrillate (P = 0.526)., Conclusions: This experimental study shows that transient myocardial ischemia markedly increases the DFT, suggesting that specific defibrillation algorithms should be designed for recipients of implantable defibrillators at risk of myocardial ischemia.

Objectives: To evaluate the effect of bone marrow pluripotent stem cell mobilization with granulocyte-monocyte colony stimulating factor (GMCSF) on infarct size and left ventricular function, in the setting of acute myocardial infarction, with a protocol easily applicable in clinical practice., Methods: Ten pigs underwent left thoracotomy and left anterior descending coronary artery occlusion for 1 h, followed by reperfusion. After 50 min of arterial occlusion, the animals were randomly divided between treatment with placebo (Group 1) and subcutaneous GM-CSF (Group 2). The thoracotomy was closed and the animals recovered. In Group 2, GM-CSF, 20 microg/kg, was administered daily, 5 days/week, for 3 weeks. Echocardiograms were obtained at 5 and 28 days after acute myocardial infarction. At 30 days, infarct size, expressed as a percentage of the whole left ventricular mass, was measured., Results: The white blood cell count increased from 13000 +/- 3338/ microl to 28700 +/- 4916/ microl (p = 0.001) in the GM-CSF-treated group. Infarct size was 7.8 +/- 6.1% in Group 1 vs 7.5 +/- 7.7% in Group 2 (ns). Similarly, no significant difference was observed between the 2 study groups in any of the echocardiographic measurements made at 28 days., Conclusions: Subcutaneous GMCSF administered during the early post acute myocardial infarction period neither decreased infarct size nor improved left ventricular function. Other protocols for mobilization of stem cells and their concentration in the injured area should be developed to combine efficacy and clinical applicability.

Study Objective: s: To examine the effects of low arterial BP (ABP) during reperfusion on the extent of myocardial infarction and on coronary blood flow (CBF) in an occlusion/reperfusion experimental model., Design: Prospective, randomized animal study., Setting: University hospital., Participants: Normal pigs that were anesthetized, intubated, and mechanically ventilated., Interventions: Twenty-seven open-chest pigs underwent occlusion of the mid left anterior descending (LAD) coronary artery for 1 h followed by reperfusion for 2 h. During reperfusion, the animals were randomly assigned to either continuous infusion of nitroglycerin in therapeutic doses and fluid infusion at rates to maintain a mean ABP >or= 80 mm Hg (group 1, n = 13), or continuous nitroglycerin infusion at rates to maintain a mean ABP between 60 mm Hg and 75 mm Hg (group 2, n = 14)., Measurements and Results: The hemodynamics and the coronary ABP distal to the occlusion were recorded throughout the experiment. In addition, the LAD CBF and peak hyperemia CBF before occlusion and during reperfusion periods were measured by transit-time flowmetry. At the end of the experiment, the infarcted left ventricular myocardial size was measured. There were no significant hemodynamic differences, including the distal coronary arterial pressure, between the two groups before or during the LAD artery occlusion period. During reperfusion, mean ABP was 90 +/- 3 mm Hg in group 1 vs 69 +/- 3 mm Hg in group 2 (p < 0.001). In group 1, the infarcted myocardium represented 50.3 +/- 4.3% of the myocardium at risk, vs 69.4 +/- 7.2% in group 2 (p < 0.001). During reperfusion, CBF and peak hyperemia CBF were significantly higher in group 1 than in group 2., Conclusions: Low ABP during reperfusion increases the size of myocardial infarction and decreases CBF.

Unlabelled: Experimental studies have described an increase in ventricular fibrillation threshold (VFT) by intravenous amiodarone. The aim of this study was to examine the early time course of changes in VFT and defibrillation thresholds (DFT) after an intravenous bolus of amiodarone in an experimental pig model of transient myocardial ischemia., Methods and Results: VFT and relative effective ventricular refractory period (ERP) were measured in 15 anaesthetized open-chest pigs after 3 min of regional coronary ischaemia before (time 0) and 2, 15, 30, 60, and 90 min after the intravenous injection of normal saline (group A, n = 5) or amiodarone, 5 mg/kg over 15 s (group B, n = 10). DFT was measured by increasing the strength of DC shocks until defibrillation was accomplished. Amiodarone caused an increase in VFT, starting at 2 min after the infusion (11.4 +/- 8.4 mA versus 9.2 +/- 4.6 mA, P = 0.03), became significant at 15 min (13.7 +/- 6.5 mA, P = 0.009), continued to rise at 30 min (34.2 +/- 28.7 mA, P = 0.03) and reached a plateau at 60 min (50.3 +/- 37.8 mA, P = 0.008). An increase was also observed in the ERP (204 +/- 25 ms at 2 min versus 197 +/- 26 ms at baseline, P = 0.074, 211 +/- 38 ms at 15 min, P = 0.084, 212 +/- 40 ms at 30 min, P = 0.037, 220 +/- 34 ms at 60 min, P = 0.002, and 227 +/- 32 ms at 90 min, P = 0.008). No change was observed in DFT after amiodarone administration. No significant change in VFT, ERP, or DFT occurred in the control group., Conclusion: In this porcine model, the intravenous administration of amiodarone increased VFT and ERP over 60 min after the injection, without effect on DFT.

Study Objectives: To examine the effects of long-term intermittent dobutamine infusion, combined with oral amiodarone in patients with congestive heart failure (CHF) refractory to standard medical treatment., Design: Prospective, randomized, double-blind, placebo-controlled clinical trial., Setting: Inpatient and outpatient heart failure clinic in a university teaching hospital., Patients and Interventions: Thirty patients with end-stage CHF refractory to standard medical treatment who could be weaned from dobutamine therapy after a first 72-h infusion were randomized in a double-blind manner to receive IV infusions of placebo (group 1; 14 patients) vs dobutamine in a dose of 10 micro g/kg/min (group 2; 16 patients) for 8 h every 14 days. All patients received standard medical therapy and also were treated with oral amiodarone, 400 mg/d, which was started at least 2 weeks before randomization., Measurements and Results: Kaplan-Meier survival analysis showed a 60% reduction in the risk of death from any cause in the group treated with the combination of dobutamine and amiodarone, compared with the group treated with placebo and amiodarone (hazard ratio, 0.403; 95% confidence interval, 0.164 to 0.992; p = 0.048). The 1-year and 2-year survival rates were 69% and 44%, respectively, in the dobutamine-treated group, vs 28% and 21%, respectively, in the placebo-treated group (p < 0.05 for both comparisons). Median survival times were 574 and 144 days, respectively, for groups 2 and 1. At 6 months, the New York Heart Association functional class was significantly improved in the patients who survived from both groups., Conclusions: Long-term intermittent dobutamine infusion combined with amiodarone added to the conventional drugs improved the survival of patients with advanced CHF that was refractory to conventional treatment.

A 44-year-old man presented with symptoms and signs of cardiac tamponade. Cytologic examination of the pericardial fluid was negative for malignancy and no manifestations of primary tumor were detected. Two weeks after pericardiocentesis the patient developed constrictive pericarditis. An emergency exploratory thoracotomy revealed a thick, fibrotic pericardium firmly adherent to the underlying myocardium. Histologic examination of the pericardium showed the presence of an adenocarcinoma, suspected to be a metastatic dissemination from a primary pulmonary source. The lymphatic spread of the tumor to the heart may explain the early development of pericardial effusion without malignant cells and the later development of pericardial and epicardial thickening. Cardiac tamponade of unknown origin should prompt a search for metastatic carcinoma, including in presence of a negative cytology.

Background: Fluid removal remains a fundamental goal in the treatment of congestive heart failure (CHF). Vacuum ultrafiltration, hemodialysis, or a combination of both was used in patients with severe CHF (NYHA class IV), severe edema, and insensitivity to pharmacological treatment with diuretics., Methods: The aim of the study was to remove the overload fluid in eighteen patients, 13 men and 5 women, aged 38 to 83, with a man age of 66 years with intractable congestive heart failure. All patients were hospitalized because of severe congestive heart failure and did not respond to treatment with intravenous administration of a high dose of diuretics and positive inotropic agents. They thus underwent vacuum ultrafiltration (1 to 27 sessions) while in 4 of them hemodialysis was also performed because of high serum creatinine levels (over 4 mg/dl). Subclavian catheters were used in all patients and arteriovenous fistula was later performed in 2, because of the need for long term treatment. The average fluid removed was 2 L per session and the total fluid removed ranged from 4 to 29 L., Results: Fourteen of the 18 patients (78%) showed significant improvement in their clinical status. Ten patients (56%) had a short term improvement but expired after 7 to 107 days of hospitalization. Four patients (22%) died after only one session of dialysis and 4 patients (22%) recovered after 8 to 23 dialysis sessions and were discharged from hospital., Conclusion: The majority of patients with severe chronic CHF which is intractable to conventional therapy including intravenous diuretics and inotropes improve by the use of ultrafiltration. However, a limited proportion of them survive to be discharged from the hospital.

Following pretreatment with ticlopidine 250 mg bid for three days, a 40-year-old man underwent successful angioplasty and stenting of the proximal left anterior descending coronary artery and balloon dilation of the midcircumflex coronary artery without stenting. He subsequently developed acute coronary thromboses at both arterial sites and cardiogenic shock. The patient survived after an additional percutaneous coronary intervention (PCI) and intra-aortic balloon pump assistance. This was followed by peripheral arterial thrombosis requiring repeated therapeutic interventions. Laboratory tests for thrombophilia revealed the presence of a G20210A prothrombin gene mutation. Two years later the patient remained free of angina and claudication, and underwent an unremarkable maximum exercise treadmill test. This is the first reported case of acute, multiple coronary and peripheral arterial thrombosis following PCI in a patient with previously unsuspected inherited thrombophilia. Inherited thrombophilia should be considered as a possible cause of arterial thrombosis following PCI.

Quantitative data concerning the effect of arterial compliance (AC) on the effectiveness of intra-aortic balloon counterpulsation (IABC) are lacking. The main objective of this study was to investigate the relationship between AC and IABC performance. For this purpose we constructed a Windkessel, lumped-element, hydraulic model of the systemic circulation. The model consisted of a left ventricular assist device (LVAD), a compliance chamber, a peripheral resistor and two open reservoirs. Two Datascope Driving systems were used to operate the LVAD and intra-aortic balloon. We studied the effect of arterial compliance on the effectiveness of IABC at different levels of mean pressure (55, 75 and 95 mmHg) and heart rates (80, 100, 120 bpm). Three indices were used to evaluate IABC performance: the reduction of systolic and end-diastolic "arterial" pressure and the augmentation of diastolic pressure, induced by the IABC. A 22% decrease in AC (1.8-1.4 ml/mmHg) lead to a 30-40% increase in the indices of IABC performance, independently from pressure. In conclusion, arterial compliance significantly affects IABC efficacy and it could be considered as a further clinical criterion to decide IABC application.