Michele Toscano

Characterization of the Hyperpolarization-Activated Current, If, in Ventricular Myocytes From Human Failing Heart

BACKGROUNDnDisease-associated electrophysiological alterations may contribute to the increased predisposition to arrhythmias of the hypertrophied or failing myocardium. An I(f)-like current is expressed in rat left ventricular myocytes (LVMs), its amplitude being linearly related to the severity of cardiac hypertrophy. Here, we report the occurrence and electrophysiological properties of I(f) in human LVMs.nnnMETHODS AND RESULTSnLVMs were isolated from hearts of three male patients undergoing cardiac transplantation for terminal heart failure due to ischemic dilated cardiomyopathy. The patch-clamp technique was used to record I(f), ie, a barium-insensitive, cesium-sensitive, time-dependent increasing inward current elicited on hyperpolarization. Membrane capacitance was 244 +/- 27 pF (n = 25). I(f) occurred in all cells tested; its density measured at -120 mV was 2.1 +/- 0.3 pA/pF. Activation curves of I(f) (n = 24) were fitted by a Boltzmann function; the threshold was -55 mV; midpoint, -70.9 +/- 2.1 mV; slope, -5.4 +/- 0.3 mV; and maximal specific conductance, 19.6 +/- 2.5 pS/pF. I(f) blockade by extracellular cesium was voltage dependent. Reducing extracellular potassium concentration from 25 to 5.4 mmol/L caused a shift of the reversal potential from -12.7 +/- 0.5 to -24.8 +/- 2.1 mV and a 64% decrease of current conductance.nnnCONCLUSIONSnI(f) is present in human LVMs. Its electrophysiological characteristics resemble those previously described in hypertrophied rat LVMs and suggest that I(f) could be an arrhythmogenic mechanism in patients with severe heart failure.

Video-assisted minimally invasive coronary operations without cardiopulmonary bypass: A multicenter study

OBJECTIVEnThe need to avoid the risks associated with cardiopulmonary bypass has led to the interest in coronary operations without cardiopulmonary bypass.nnnPATIENTS AND METHODSnFrom April 1994 to September 1995, 44 patients (mean age 63.3 +/- 10.0 years, range 43 to 83 years) were selected for video-assisted coronary artery bypass grafting without cardiopulmonary bypass through a small anterior thoracotomy. Mean preoperative ejection fraction was 50.7% +/- 13.4% (range 20% to 65%). Four patients had left ventricular dysfunction (ejection fraction below 35%). Thirty patients had stable angina (26 with class 3 angina) and 14 had unstable angina. One had recurrent angina (redo). In all cases a small (3.5 to 11 cm) anterior thoracotomy (43 left and one right) was performed and the harvesting of the left internal thoracic artery was video-assisted by thoracoscopy.nnnRESULTSnThe left internal thoracic artery was used in 43 cases to graft the left anterior descending coronary artery; the right thoracic mammary was used in one case to graft the right coronary artery; the radial artery was used in one case to perform a T-graft to the first diagonal and first marginal branches. We recorded one death (2.3%) and one case of postoperative low cardiac output syndrome (2.3%). Perioperative myocardial infarction occurred in two cases (4.5%). We did not record noncardiac complications (cerebrovascular complications, kidney failure, prolonged ventilatory support, or wound complications). Supraventricular and ventricular arrhythmias were never detected.nnnCONCLUSIONnAccording to our experience, video-assisted coronary bypass through a small anterior thoracotomy is a new promising technique that can be considered an alternative in most cases to angioplasty and complementary to conventional coronary operations.

Mid-term outcome of surgical coronary ostial plasty: our experience.

The conventional coronary artery bypass procedure that uses venous or arterial conduit for isolated critical stenosis of the left main coronary artery (LMCA) restores a less physiological perfusion of the myocardium and uses an appreciable length of bypass material, Coronary ostial plasty has been described as an alternative surgical technique in proximal obstructive coronary artery disease without calcifications. Here we report 23 patients (15 males and 8 females aged 37–78 years; mean age 57 years) who underwent surgical ostial plasty. Ostial reconstruction with fresh pericardial patch was performed in all patients: 15 patients with LMCA stenosis, 6 patients with right coronary (RC) ostial stenosis. and 2 patients with both RC artery and LMCA stenosis. In seven cases, coronary artery bypass grafting was added for contralateral distal stenosis with a total of five arterial conduits and six venous grafts. One patient died; the ostial plasty and grafts were patent at necropsy. Thal‐lium‐201 myocardial scintigraphy under stress at 30 days to 6 months after operation demonstrated good myocardial perfusion in 21 of 22 patients. Coronary angiography at follow‐up (49 ± 8 months) demonstrated good surgical ostial plasty results in 21 of 22 patients and good coronary flow in 19 of 22 patients; angiographic study at mid‐term follow‐up revealed only one failure of the surgical ostial plasty technique associated with venous graft obstruction. In 2 other patients CABG failure due to venous graft obstruction (1 patient) or distal stenotic lesions of the left coronary artery (1 patient) was noted. The overall successful outcome of the surgical ostial plasty was 22 of 23. We believe that surgical angioplasty of the coronary ostia may be used in the presence of proximal noncalcified obstructive lesions as an alternative technique, which offers a more physiological revascularization; it also spares grafting material and allows subsequent percutaneous transluminal angioplasty or coronary artery bypass surgery.

Warm Heart Surgery Eliminates Diaphragmatic Paralysis

Since January 1992, we adopted a new method of myocardial protection: warm blood cardioplegia with continuous ante‐retrograde combined delivery during normothermic cardiopulmonary bypass, (CPB) instead of cold blood intermittent cardioplegia plus topical ice slush in hypothermic CPB. We have compared postoperative chest X‐rays of 50 patients who underwent elective coronary artery bypass with normothermic CPB to postoperative chest X‐rays, of 50 patients operated upon with hypothermia. In the cold group transitory diaphragmatic paralysis, as well as pleural effusions and thoracentesis related to the hypothermia, and topical cooling, were statistically increased over that of the warm group. The data suggest that topical cooling with slush ice is responsible for phrenic nerve injury and that warm heart surgery has no associated incidence of diaphragmatic injury.

Reduction of oxidative stress does not affect recovery of myocardial function: warm continuous versus cold intermittent blood cardioplegia.

OBJECTIVE: To compare oxidative stress after cardiac surgery in patients treated with two different methods of myocardial protection: warm continuous versus cold intermittent blood cardioplegia. To correlate oxidative stress with postoperative myocardial dysfunction. DESIGN: Prospective, randomised, double blind, trial. SETTING: Institutional centre of cardiovascular surgery. PATIENTS: 20 patients were selected for coronary artery bypass surgery (CABG) on the following basis: stable angina, ejection fraction > 50%, double or triple vessel disease, no previous CABG or associated disease. Patients were randomised to two groups of 10 patients each. INTERVENTIONS: Patients underwent CABG with one of two different methods of myocardial protection and cardiopulmonary bypass. CBC group: intermittent cold blood antegrade-retrograde cardioplegia with moderate hypothermic cardiopulmonary bypass; WBC group: continuous warm blood antegrade-retrograde cardioplegia with mild hypothermic cardiopulmonary bypass. MAIN OUTCOME MEASURE: The index of oxidative stress used was the alteration of whole blood and plasma glutathione redox status. Samples were collected from the coronary sinus and peripheral vein before anaesthesia (T1), before aortic unclamping (T2), 15 minutes (T3), and 30 minutes (T4) after unclamping. Haemodynamic parameters were measured with thermodilution techniques. RESULTS: Oxidised glutathione and glutathione-cysteine mixed disulphide significantly increased in the coronary sinus plasma in the CBC group, and the overall redox balance of glutathione was decreased (P < 0.01) at T2-T4 versus T1, and compared with the WBC group. Comparable results were obtained for coronary sinus blood. There was no correlation between postoperative haemodynamic measurements and oxidative stress markers. CONCLUSIONS: Oxidative stress was significant in patients undergoing CABG using cold blood cardioplegia, while the warm technique minimised the effects of ischaemia. However, oxidative stress was not correlated with myocardial dysfunction following CABG.

Uncommon intrathoracic extrapulmonary tumor: Primary hemangiopericytoma

We report an unusual case of primary intrathoracic extrapulmonary hemangiopericytoma. Despite the large size and rapid growth of the tumor, no histological sign of malignancy was present. Tumor cells immunostained positively only to vimentin.

Total arterial myocardial revascularization without cardiopulmonary bypass

The risks associated with cardiopulmonary bypass have led to an interest in coronary surgery without the use of such a bypass. Six patients of mean(s.d.) age 62.0(8.0) (range 52-71) years were selected for elective coronary surgery without cardiopulmonary bypass. In five cases a midline sternotomy and in one case a small anterolateral thoracotomy were performed; in the latter case the harvesting of the proximal end of the left internal mammary artery was video-assisted by thoracoscopy. The left internal mammary artery was used in all cases; the right internal mammary artery was used in one case, the radial artery in four, the inferior epigastric artery in two and the right gastroepiploic artery inn one. No patient died or had a stroke. There were no postoperative episodes of low cardiac output syndrome or perioperative myocardial infarction. All patients were extubated within a few hours after surgery. The mean(s.d.) intensive care unit and hospital stays were 1.3(0.5) and 5.0(0.9) days, respectively. Total arterial myocardial revascularization without cardiopulmonary bypass using composite grafts, is a new and promising technique that is feasible with low risks and good early results in selected cases.

Mid-Term Outcome of Surgical Coronary Ostial Plasty: Our Experience

Abstract The conventional coronary artery bypass procedure that uses venous or arterial conduit for isolated critical stenosis of the left main coronary artery (LMCA) restores a less physiological perfusion of the myocardium and uses an appreciable length of bypass material, Coronary ostial plasty has been described as an alternative surgical technique in proximal obstructive coronary artery disease without calcifications. Here we report 23 patients (15 males and 8 females aged 37–78 years; mean age 57 years) who underwent surgical ostial plasty. Ostial reconstruction with fresh pericardial patch was performed in all patients: 15 patients with LMCA stenosis, 6 patients with right coronary (RC) ostial stenosis. and 2 patients with both RC artery and LMCA stenosis. In seven cases, coronary artery bypass grafting was added for contralateral distal stenosis with a total of five arterial conduits and six venous grafts. One patient died; the ostial plasty and grafts were patent at necropsy. Thal‐lium‐201 myocardial scintigraphy under stress at 30 days to 6 months after operation demonstrated good myocardial perfusion in 21 of 22 patients. Coronary angiography at follow‐up (49 ± 8 months) demonstrated good surgical ostial plasty results in 21 of 22 patients and good coronary flow in 19 of 22 patients; angiographic study at mid‐term follow‐up revealed only one failure of the surgical ostial plasty technique associated with venous graft obstruction. In 2 other patients CABG failure due to venous graft obstruction (1 patient) or distal stenotic lesions of the left coronary artery (1 patient) was noted. The overall successful outcome of the surgical ostial plasty was 22 of 23. We believe that surgical angioplasty of the coronary ostia may be used in the presence of proximal noncalcified obstructive lesions as an alternative technique, which offers a more physiological revascularization; it also spares grafting material and allows subsequent percutaneous transluminal angioplasty or coronary artery bypass surgery. (J Card Surg 7999; 14:294–300)