Guido Sani

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

BACKGROUND Disease-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. METHODS AND RESULTS LVMs 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. CONCLUSIONS I(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.

Does ministernotomy improve postoperative outcome in aortic valve operation? A prospective randomized study

BACKGROUND The aim of this study was to compare the postoperative outcome obtained in patients undergoing elective aortic valve operation, either through ministernotomy or conventional sternotomy. METHODS Between January 1999 and July 2001, 80 consecutive patients undergoing elective aortic valve replacement were randomly divided into two groups: group I (n = 40 patients) undergoing a ministernotomy approach (reversed-C or reversed-L), and group II (n = 40 patients) undergoing conventional sternotomy. RESULTS The length of skin incision was significantly shorter in group I than in group II (8.2+/-1.3 cm versus 23.7+/-2.6 cm, p < 0.001). No significant differences were found in cardiopulmonary bypass duration, associated procedures, or aortic cross-clamping times. Total operating time was 3.7+/-0.46 hours in group I compared with 3.4+/-0.6 hours in group II (p = 0.014). A similar incidence of cardiac, neurologic, infective, and renal complications between groups was found. Mean mediastinal drainage and mean blood transfusions (amount of blood transfused) per patient were greater in group II (p < 0.004 and p < 0.001, respectively). Twenty-five (62.5%) patients in group II and 15 (37.5%) patients in group I required postoperative blood transfusion (p = 0.04). Mechanical ventilation time was significantly longer in group II (6.2+/-1.8 hours versus 4.4+/-0.9 hours, p = 0.006). Five days after the surgical procedure, spirometric data analysis demonstrated a significantly lower total lung capacity and maximum inspiratory and expiratory pressures in group II compared with group I (p = 0.003, p = 0.007, and p < 0.001, respectively). CONCLUSIONS Our results showed that ministernotomy had not only important cosmetic advantages but also beneficial effects in blood loss and transfusion, postoperative pain, and probably in sternal stability. Ministernotomy also improved recovery of respiratory function and allowed earlier extubation and hospital discharge.

Cardiac Growth Factors in Human Hypertrophy Relations With Myocardial Contractility and Wall Stress

The aim of the present study was to investigate whether and which cardiac growth factors are involved in human hypertrophy, whether growth factor synthesis is influenced by overload type and/or by the adequacy of the hypertrophy, and the relationships between cardiac growth factor formation and ventricular function. Cardiac growth factor formation was assessed by measuring aorta-coronary sinus concentration gradient in patients with isolated aortic stenosis (n=26) or regurgitation (n=15) and controls (n=12). Gene expression and cellular localization was investigated in ventricular biopsies using reverse transcriptase-polymerase chain reaction and in situ hybridization. Cardiac hypertrophy with end-systolic wall stress <90 kdyne/cm2 was associated with a selective increased formation of insulin-like growth factor (IGF)-I in aortic regurgitation and of IGF-I and endothelin (ET)-1 in aortic stenosis. mRNA levels for IGF-I and preproET-1 were elevated and mainly expressed in cardiomyocytes. At stepwise analysis, IGF-I formation was correlated to the mean velocity of circumferential fiber shortening (r=0.86, P<0.001) and ET-1 formation to relative wall thickness (r=0.82, P<0. 001). When end-systolic wall stress was >90 kdyne/cm2, IGF-I and ET-1 synthesis by cardiomyocytes was no longer detectable, and only angiotensin (Ang) II was generated, regardless of the type of overload. The mRNA level for angiotensinogen was high, and the mRNA was exclusively expressed in the interstitial cells. Ang II formation was positively correlated to end-systolic stress (r=0.89, P<0.001) and end-diastolic stress (r=0.84, P<0.001). Multivariate stepwise analysis selected end-systolic stress as the most predictive variable and left ventricular end-diastolic pressure as the independent variable for Ang II formation (r=0.93, P<0.001). In conclusion, the present results indicate that the course of human left ventricular hypertrophy is characterized by the participation of different cardiac growth factors that are selectively related both to the type of hemodynamic overload and to ventricular function.

Selective Upregulation of Cardiac Endothelin System in Patients With Ischemic but Not Idiopathic Dilated Cardiomyopathy: Endothelin-1 System in the Human Failing Heart

Only scarce information is available on the activity and modifications of the cardiac endothelin (ET)-1 system in heart failure due to ischemic (ICM) or idiopathic dilated (DCM) cardiomyopathy. The activity of the ET-1 system was investigated by measuring cardiac ET-1 and big ET-1 formation and quantifying cardiac mRNA for prepro-ET-1 (ppET-1), ET-converting enzyme-1, and ET(A) and ET(B) receptors both in myocardium and in isolated myocytes using Northern blot, reverse transcription-polymerase chain reaction, and in situ hybridization in 22 patients with DCM and 20 with ICM who underwent cardiac transplantation and in 7 potential heart transplant donors (nonfailing hearts). Notwithstanding a similar increase of plasma ET-1 in the 2 groups, cardiac ET formation, mRNA levels for ppET-1, and ET(A) and ET(B) receptors were higher on both the myocardium and isolated myocytes from ICM than on those from DCM hearts (P<0.001 for all). ppET-1 and ET-converting enzyme-1 mRNAs were expressed on myocytes and endothelial and interstitial cells in ICM, whereas in DCM and nonfailing hearts they were mainly expressed on nonmyocyte cells. In both ICM and DCM, the ET(A) mRNA signal was expressed on both myocytes and nonmyocyte cells, whereas ET(B) mRNA was almost exclusively localized on nonmyocyte cells. ET(A)- and ET(B)-specific receptor binding was increased on both myocytes and cardiac membranes, showing a positive correlation with left ventricular ejection fraction in ICM (r=0.78 and 0.70) but not in DCM patients. The present results show that human ventricular myocytes express all of the components of the ET-1 system, which is selectively upregulated in ICM patients and appears to be functionally important in the maintenance of cardiac function.

Respiratory dysfunction after coronary artery bypass grafting employing bilateral internal mammary arteries: the influence of intact pleura

OBJECTIVE To evaluate the role of intact pleurae regarding the postoperative respiratory functional status in patients undergoing coronary revascularization employing both internal mammary arteries (IMAs), according to the pedunculated or skeletonized technique (SKT) with opened or intact pleurae. MATERIALS AND METHODS Using both IMAs, 299 patients underwent elective coronary revascularization. They were randomized and divided into group I (n=82, undergoing IMA harvesting according to the SKT without opening the pleurae); group II (n=186, undergoing IMA harvesting according the pedunculated technique with open pleurae); and group III (n=31, undergoing IMA harvesting according the SKT with incidentally opened pleurae). There were no differences regarding the preoperative patient characteristics and the anaesthetic and surgical management. RESULTS There were two deaths in group I versus seven in group II and one in group III (P=ns). The number of total arterial myocardial revascularization and arterial composite grafts was significantly higher in groups I and III than in group II, (P<0.001 and P<0.005, respectively). The incidence of postoperative complications was similar between groups. Blood loss of >1000 ml was significantly higher in group II than group I (P<0.028); but the incidence of re-thoracotomy and blood transfusion was similar between groups. The mechanical ventilation time was significantly higher in groups II and III versus group I (P<0.018 and P<0.02, respectively). The incidence of prolonged ventilation (>24 h), pleural effusion, thoracocentesis and atelectasis, resulted in being significantly higher in group II than group I. The incidence of thoracocentesis was significantly higher in group III than group I. The pain score and analgesic requirements at 1-12 h after awakening were significantly higher in groups II and III versus group I, becoming similar after the chest tubes were removed. PaO(2) was significantly higher, and PaCO(2) and FiO(2) were significantly lower in group I than groups II and III at 1 and 4 h before extubation and at 1 and 4 h after extubation. PaO(2) and PaCO(2) became similar between groups at the 5th postoperative day. CONCLUSIONS According to our results, we may conclude that pleural integrity has beneficial effects on the respiratory functional status after coronary revascularization using both IMAs. A meticulous and more careful IMA harvesting approach significantly reduces the postoperative morbidity regarding the pulmonary functional status, and as a consequence, reduces the hospital costs.

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

OBJECTIVE The need to avoid the risks associated with cardiopulmonary bypass has led to the interest in coronary operations without cardiopulmonary bypass. PATIENTS AND METHODS From 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. RESULTS The 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. CONCLUSION According 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.

Should Mild‐to‐Moderate and Moderate Ischemic Mitral Regurgitation Be Corrected in Patients with Impaired Left Ventricular Function Undergoing Simultaneous Coronary Revascularization?

Introduction: Mitral valve regurgitation (MR) occurring as a result of myocardial ischemia and global left ventricular (LV) dysfunction predicts poor outcome. This study assessed the feasibility of mitral valve (MV) surgery concomitant with coronary artery bypass grafting (CABG) in patients with mild‐to‐moderate and moderate ischemic MR and impaired LV function. Materials and Method: From January 1996 to July 2000, 49 patients (group 1) and 50 patients (group 2) with grade II and grade III ischemic MR and LV ejection fraction (EF) between 17% and 30% underwent combined MV surgery and CABG (group 1) or isolated CABG (group 2). LVEF (%), LV end‐diastolic diameter (EDD) (mm), LV end‐diastolic pressure (EDP) (mmHg), and LV end‐systolic diameter (ESD) (mm) were 27.5 ± 5, 67.7 ± 7, 27.7 ± 4, and 51.4 ± 7, respectively in group 1 versus 27.8 ± 4, 67.5 ± 6, 27.5 ± 5, and 51.2 ± 6, respectively in group 2. Groups 1 and 2 were divided into Groups 1A and 2A with mild‐to‐moderate MR (22 [45%] and 28 [56%] patients, respectively) and groups 1B and 2B with moderate MR (27 [55%] and 22 [46%], respectively). In group 1, MV repair was performed in 43 (88%) patients and MV replacement in 6 (12%) patients. Results: Preoperative data analysis did not reveal any difference between groups. Five (10%) patients in group 1 died versus 6 (12%) in group 2 (p = ns). Within 6 months after surgery, LV function and its geometry improved significantly in group 1 versus group 2 (LVEF, p < 0.001; LVEDD, p = 0.002; LVESD, p = 0.003; and LVEDP (p < 0.001) improved significantly in group 1 instead of a mild improvement in Group 2). The regurgitation fraction decreased significantly in group 1 patients after surgery (p < 0.001). There was an inverse strong correlation between postoperative forward cardiac output and regurgitation fraction (p < 0.001). LVEF and LVESD improved significantly in group versus group 2 patients (p = 0.04 and p = 0.02, respectively). The cardiac index increased significantly in group 1 and 2 (p < 0.001 and p = 0.03, respectively). LV function and geometry improved significantly postoperatively in group 1B versus group 2B (LVEDD, p = 0.027; LVESD, p = 0.014; LVEDP, p = 0.034; and LVEF, p = 0.02), instead of a mild improvement in group 1A versus group 2A (LVESD, p = 0.015; LVEF, p = 0.046; and LVEDD and LVEDP, p = 0.05). At follow‐up, 4 (67%) of 6 patients undergoing MV replacement died versus 5 (11.59/0) of patients undergoing MV repair in group 1 (p = 0.007). The overall survival at 3 years in Group 2 was significantly lower than group 1 (p < 0.009). Conclusion: MV repair and replace‐ ment‐preserving subvalvular apparatus in patients with impaired LV function offered acceptable outcomes in terms of morbidity and survival. Surgical correction of mild‐to‐moderate and moderate MR in patients with impaired LV function should be taken into consideration since yields better survival and improved LV function.

Ventilatory and ECMO treatment of H1N1-induced severe respiratory failure: results of an Italian referral ECMO center.

BackgroundSince the first outbreak of a respiratory illness caused by H1N1 virus in Mexico, several reports have described the need of intensive care or extracorporeal membrane oxygenation (ECMO) assistance in young and often healthy patients. Here we describe our experience in H1N1-induced ARDS using both ventilation strategy and ECMO assistance.MethodsFollowing Italian Ministry of Health instructions, an Emergency Service was established at the Careggi Teaching Hospital (Florence, Italy) for the novel pandemic influenza. From Sept 09 to Jan 10, all patients admitted to our Intensive Care Unit (ICU) of the Emergency Department with ARDS due to H1N1 infection were studied. All ECMO treatments were veno-venous. H1N1 infection was confirmed by PCR assayed on pharyngeal swab, subglottic aspiration and bronchoalveolar lavage. Lung pathology was evaluated daily by lung ultrasound (LUS) examination.ResultsA total of 12 patients were studied: 7 underwent ECMO treatment, and 5 responded to protective mechanical ventilation. Two patients had co-infection by Legionella Pneumophila. One woman was pregnant. In our series, PCR from bronchoalveolar lavage had a 100% sensitivity compared to 75% from pharyngeal swab samples. The routine use of LUS limited the number of chest X-ray examinations and decreased transportation to radiology for CT-scan, increasing patient safety and avoiding the transitory disconnection from ventilator. No major complications occurred during ECMO treatments. In three cases, bleeding from vascular access sites due to heparin infusion required blood transfusions. Overall mortality rate was 8.3%.ConclusionsIn our experience, early ECMO assistance resulted safe and feasible, considering the life threatening condition, in H1N1-induced ARDS. Lung ultrasound is an effective mean for daily assessment of ARDS patients.

Speckle tracking echocardiography as a new technique to evaluate right ventricular function in patients with left ventricular assist device therapy.

BACKGROUND Right ventricular (RV) systolic function has a critical role in determining the clinical outcome and the success of using left ventricular assist devices (LVADs) in patients with refractory heart failure. RV deformation analysis by speckle tracking echocardiography (STE) has recently allowed a deeper analysis of RV longitudinal function. The aim of the study was to observe RV function by STE in patients with advanced heart failure before and after LVAD implantation. METHODS Transthoracic echo Doppler was performed in 10 patients referred for LVAD therapy at baseline and with serial echocardiograms after LVAD implantation. In a sub-group of 4 patients, an echocardiographic evaluation was also made after intra-aortic balloon pump (IABP) support was initiated and before LVAD implantation. All echocardiographic images were analyzed off-line to calculate the free wall RV longitudinal strain (RVLS). RESULTS Three patients who presented the lowest free wall RVLS values at baseline, showed a progressive decline of RVLS after LVAD implant, presenting finally RV failure; however, patients with higher values of RVLS at baseline presented a further and overt increase of strain values in the course of follow-up. The overall performance for the prediction of RV failure after LVAD implant was greatest for free wall RVLS (area under the curve, 0.93). For the sub-group receiving the IABP as an intermediate step, only 2 patients with an increase of RVLS after IABP implantation also showed an increase of RVLS levels, after subsequent LVAD implantation. The 2 patients without an increase of RVLS after IABP implantation also presented with RV failure after LVAD therapy. CONCLUSIONS This study of 10 patients indicates that the new parameter of RVLS, representing RV myocardial deformation, may have important clinical implications for the selection and management of LVAD patients. A large multicenter study is required to confirm these observations and to quantify the clinical significance of changes in RVLS value.

Characterization of endothelin-1 receptor subtypes in isolated human cardiomyocytes.

On cardiac membranes and isolated cardiomyocytes from the human heart, cell-type distribution and functional activities of endothelin-1 (ET-1) receptor subtypes were investigated by using binding methods and messenger RNA (mRNA) in situ hybridization. The ET-receptor antagonist BMS-182874 selectively and competitively inhibits ET(A) receptors both on isolated myocytes and ventricular membranes with approximately 1,300 times greater affinity for ET(A) than ET(B) subtypes. The [125I]-ET-1 specific binding revealed 42.851+/-2,546 receptors/myocyte with a prevalent proportion of ET(A)-receptor subtypes on both myocytes (84+/-2%) and ventricular membranes (66+/-3%). In situ hybridization studies revealed that mRNA for ET(A) receptors was expressed on both myocytes and nonmyocyte cells, whereas mRNA for ET(B) receptors was almost exclusively expressed on fibroblasts and endothelial cells. Specific binding of [125I]-ET-1 to both myocytes and ventricular membranes in the presence of specific ET(A) (BMS-182874) and ET(B) (BQ-788)-receptor antagonists showed a displacement of [125I]-ET-1 by unlabeled ET-1, which were significantly faster from ET(B) than from ET(A). This suggests a clearance function of ventricular ET(B) receptors.