Implementation of an epicardial implantable MEMS sensor for continuous and real-time postoperative assessment of left ventricular activity in adult minipigs over a short- and long-term period.

The sensing of left ventricular (LV) activity is fundamental in the diagnosis and monitoring of cardiovascular health in high-risk patients after cardiac surgery to achieve better short- and long-term outcome. Conventional approaches rely on noninvasive measurements even if, in the latest years, invasive microelectromechanical systems (MEMS) sensors have emerged as a valuable approach for precise and continuous monitoring of cardiac activity. The main challenges in designing cardiac MEMS sensors are represented by miniaturization, biocompatibility, and long-term stability. Here, we present a MEMS piezoresistive cardiac sensor capable of continuous monitoring of LV activity over time following epicardial implantation with a pericardial patch graft in adult minipigs. In acute and chronic scenarios, the sensor was able to compute heart rate with a root mean square error lower than 2 BPM. Early after up to 1 month of implantation, the device was able to record the heart activity during the most important phases of the cardiac cycle (systole and diastole peaks). The sensor signal waveform, in addition, closely reflected the typical waveforms of pressure signal obtained via intraventricular catheters, offering a safer alternative to heart catheterization. Furthermore, histological analysis of the LV implantation site following sensor retrieval revealed no evidence of myocardial fibrosis. Our results suggest that the epicardial LV implantation of an MEMS sensor is a suitable and reliable approach for direct continuous monitoring of cardiac activity. This work envisions the use of this sensor as a cardiac sensing device in closed-loop applications for patients undergoing heart surgery.

Prognostic value of pulmonary blood volume by first-pass contrast-enhanced CMR in heart failure outpatients: the PROVE-HF study.

Aims: Pulmonary blood volume (PBV) is a novel clinical application of cardiovascular magnetic resonance (CMR) imaging for the quantitative grading of haemodynamic congestion. In this study, we aimed to assess the prognostic value of PBV in a cohort of outpatients with chronic heart failure (HF). Methods and results: One hundred and twelve consecutive patients (91 men, 67 ± 12 years) and 53 age- and sex-matched healthy controls underwent echocardiography and contrast-enhanced CMR. PBV was calculated as the product of stroke volume and the number of cardiac cycles for an intravenous bolus of gadolinium contrast to pass through the pulmonary circulation determined by first-pass perfusion imaging. Compared with healthy controls, HF outpatients showed significantly higher PBV index (PBVI, 308 ± 92 vs. 373 ± 175, mL/m2, P = 0.012) and pulmonary transit time (6.8 ± 1.8 vs. 9.5 ± 4 s, P ≤0.001). During a median follow-up of 26 ± 17 months, 27 patients (24%) reached the composite end point of cardiovascular death, HF hospitalization, or sustained ventricular arrhythmias/appropriate implantable cardioverter-defibrillator intervention. Using a cut-off point of PBVI >492 mL/m2, corresponding to two standard deviations above the mean of healthy controls, event-free survival was significantly lower in patients with higher PBVI (P < 0.001). At multivariable-adjusted Cox regression analysis, PBVI was an independent predictor of the composite cardiovascular end point (per 10% increase hazard ratio 1.31, 95% confidence interval: 1.02-1.69, P = 0.03). Conclusions: PBVI is a novel application of perfusion CMR potentially useful to quantitatively determine haemodynamic congestion as a surrogate marker of left ventricular diastolic dysfunction. PBVI might prove to be helpful in stratifying the prognosis of asymptomatic or mildly symptomatic patients with left ventricular dysfunction.

Evaluation of Distensibility and Stiffness of Ascending Aortic Aneurysm using Magnetic Resonance Imaging.

INTRODUCTION: Magnetic resonance imaging emerging as a new tool for the diagnosis and evaluation of ascending aortic aneurysm. The aim of our study is to evaluate in vivo distensibility and pulse wave velocity of the aortic wall using functional magnetic resonance imaging technique. METHODS: We enrolled 25 patients undergoing surgery for ascending aortic aneurysm and or aortic valve replacement for a period of 8 months. Preoperatively, all the patients underwent functional MRI study of the aorta. Aortic wall distensibility and pulse wave velocity of ascending aorta was evaluated. RESULTS: Mean age of the patient was 66 years (66.68 ± 5.62 years) with 60% (15) male patients. More than fifty percentages of patients were smoker (52%), hypertensive (64%) and diabetic (56%). We have observed significant decrease of distensibilty in the patients with aortic diameter above 50 mm (p-0.0002). Furthermore, we have found a significant inverse correlation between aortic distensibility and pulse wave velocity (R= -0.650, R2= 0.42, p-0.0004). Similarly, we have found a significant inverse correlation between ascending aortic diameter and distensibility of the aorta (R= -0.785, R2= 0.61, p-0.00001). Statistically significant positive correlation was observed between aortic diameter and pulse wave velocity (R= 0.865, R2= 0.74, p-0.00001). CONCLUSIONS: MRI measurement of aortic diameters, distensibility, and flow wave velocity is an easy, reliable and reproducible technique. Distensibility and pulse wave velocity define the elasticity of the aorta. We have observed that elasticity of aortic wall is decreased in ascending aorta aneurysm patients.

Quantitative criteria for the diagnosis of the congenital absence of pericardium by cardiac magnetic resonance.

BACKGROUND: Congenital absence of the left ventricular pericardium (LCAP) is a rare and poorly known cardiac malformation. Cardiac Magnetic Resonance (CMR) is generally used for the diagnosis of LCAP because of its high soft tissue contrast, multiplanarity and cine capability, but the diagnosis is usually made by only qualitative criteria. The aim of the present study was to establish quantitative criteria for the accurate diagnosis of LCAP on CMR. METHODS: We enrolled nine consecutive patients affected by LCAP (mean age 26±8years, 7 males), 13 healthy controls, 13 patients with dilated cardiomyopathy (DCM), 12 patients with hypertrophic cardiomyopathy (HCM) and 13 patients with right ventricular overload (RVO). All patients underwent CMR. The whole-heart volume was measured in end-systole and end-diastole. Whole-heart volume change (WHVC), was the systo-diastolic change of volume, expressed percentage of the end-diastolic volume. The angle of clockwise-rotation of the heart was also measured in the end-diastolic phase of the axial cine stack. RESULTS: The WHVC was significantly higher in LCAP (21.9±5.4), compared to healthy subjects (8.6±2.4, p<0.001), DCM (7.1±1.8, p<0.001), HCM (9.3±2.4, p<0.001) and RVO (8±2.4, p<0.001). The clockwise-rotation was significantly higher in LCAP (76±14°) than healthy controls (40±11°, p<0.001), DCM (41±5°, p<0.001), HCM (30±6°, p<0.001) and RVO (49±8°, p<0.001). WHVC had the highest sensitivity (100%) and specificity (100%) for diagnosing LCAP, using a threshold of >13%. CONCLUSIONS: In LCAP the systo-diastolic WHVC was significantly higher than controls, DCM, HCM and RVO patients and resulted an optimal quantitative criteria for the diagnosis of LCAP.

Measurement of myocardial amyloid deposition in systemic amyloidosis: insights from cardiovascular magnetic resonance imaging.

BACKGROUND: Cardiac involvement in systemic amyloidosis is caused by the extracellular deposition of misfolded proteins, mainly immunoglobulin light chains (AL) or transthyretin (ATTR), and may be detected by cardiovascular magnetic resonance (CMR). The aim of this study was to measure myocardial extracellular volume (ECV) in amyloid patients with a novel T1 mapping CMR technique and to determine the correlation between ECV and disease severity. METHODS: Thirty-six patients with biopsy-proven systemic amyloidosis (mean age 70 ± 9 years, 31 men, 30 with AL and six with ATTR amyloidosis) and seven patients with possible amyloidosis (mean age 64 ± 10 years, six men) underwent comprehensive clinical and CMR assessment, with ECV estimation from pre- and postcontrast T1 mapping. Thirty healthy subjects (mean age 39 ± 17 years, 21 men) served as the control group. RESULTS: Amyloid patients presented with left ventricular (LV) concentric hypertrophy with impaired biventricular systolic function. Cardiac ECV was higher in amyloid patients (definite amyloidosis, 0.43 ± 0.12; possible amyloidosis, 0.34 ± 0.11) than in control subjects (0.26 ± 0.04, P < 0.05); even in amyloid patients without late gadolinium enhancement (0.35 ± 0.10), ECV was significantly higher than in the control group (P < 0.01). A cut-off value of myocardial ECV >0.316, corresponding to the 95th percentile in normal subjects, showed a sensitivity of 79% and specificity of 97% for discriminating amyloid patients from control subjects (area under the curve of 0.884). Myocardial ECV was significantly correlated with LV ejection fraction (R(2)  = 0.16), LV mean wall thickness (R(2)  = 0.41), LV diastolic function (R(2)  = 0.21), right ventricular ejection fraction (R(2)  = 0.13), N-terminal fragment of the pro-brain natriuretic peptides (R(2)  = 0.23) and cardiac troponin (R(2)  = 0.33). CONCLUSION: Myocardial ECV was increased in amyloid patients and correlated with disease severity. Thus, measurement of myocardial ECV represents a potential noninvasive index of amyloid burden for use in early diagnosis and disease monitoring.

High concentration of C-type natriuretic peptide promotes VEGF-dependent vasculogenesis in the remodeled region of infarcted swine heart with preserved left ventricular ejection fraction.

BACKGROUND: Vasculogenesis is a hallmark of myocardial restoration. Post-ischemic late remodeling is associated with pathology and function worsening. At the same time, neo-vasculogenesis helps function improving and requires the release of vascular endothelial growth factor type A (VEGF-A). The vasculogenic role of C-type natriuretic peptide (CNP), a cardiac paracrine hormone, is unknown in infarcted hearts with preserved left ventricular (LV) ejection fraction (EF). We explored whether myocardial VEGF-dependent vasculogenesis is affected by CNP. METHODS AND RESULTS: To this end, infarcted swine hearts were investigated by magnetic resonance imaging (MRI), histological and molecular assays. At the fourth week, MRI showed that transmural myocardial infarction (MI) affected approximately 13% of the LV wall mass without impairing global function (LVEF>50%, n=9). Increased fibrosis, metalloproteases and capillary density were localized to the infarct border zone (BZ), and were associated with increased expression of CNP (p=0.03 vs. remote zone (RZ)), VEGF-A (p<0.001 vs. RZ), BNP, a marker of myocardial dysfunction (p<0.01 vs. RZ) and the endothelial marker, factor VIII-related antigen (p<0.01 vs. RZ). In vitro, CNP 1000 nM promoted VEGF-dependent vasculogenesis without affecting the cell growth and survival, although CNP 100 nM or a high concentration of VEGF-A halted vascular growth. CONCLUSIONS: CNP expression is locally increased in infarct remodeled myocardium in the presence of dense capillary network. The vasculogenic response requires the co-exposure to high concentration of CNP and VEGF-A. Our data will be helpful to develop combined myocardial delivery of CNP and VEGF-A genes in order to reverse the remodeling process.

Effects of somatostatin analogues on acromegalic cardiomyopathy: results from a prospective study using cardiac magnetic resonance.

OBJECTIVE: Left ventricular (LV) hypertrophy is the main finding of patients with active acromegaly at cardiac magnetic resonance (CMR). The aim of the study was to evaluate heart changes in acromegalic patients treated with somatostatin analogues (SMSA) using CMR. DESIGN AND PATIENTS: This was a prospective study. Fourteen consecutive patients (8 women, mean age 46+/-10 yr) with untreated active acromegaly were submitted to CMR and 2D-color Doppler echocardiography before and after a 6-month SMSA course. MEASUREMENTS: LV volume, mass (LVM) and wall thickness. RESULTS: CMR: Mean LVM and LVM index (i) decreased from 151+/-17 g and 77+/-9 g/m2, to 144+/-24 g and 70+/-12 g/m2, respectively (p=0.047 and p<0.0001, respectively); LV hypertrophy reverted in 6 out of 10 patients (p=0.016). Systolic function, evaluated by measuring LV ejection fraction remained normal in all patients (67+/-11%). There was not a correlation between changes in LVMi and changes in serum IGF-I concentrations. However, patients with controlled disease had higher reduction of LVMi than those with uncontrolled acromegaly (DeltaLVMi, -8.2+/-4.2 vs 4.0+/-5.3 p<0.05). 2D-echo cardiography: Mean LVMi decreased from 110+/-24 g/m2 to 100+/-20 g/m2 (p=0.026); hypertrophy, revealed in 5 patients (36%) at baseline, reversed in 2 patients (p=0.500) after SMSA; abnormal diastolic function [evaluated by isovolumic relaxation time or early (E) to late of atrial (A) peak velocities ratio] found in 4 patients (29%) at the study entry, improved in a patient. Systolic function remained within the normal range in all patients during the study period. CONCLUSIONS: CMR detects changes in LVMi in most patients with acromegaly treated with SMSA, which are more evident if the disease is controlled.

[Cardiac troponin I and T in unstable angina: incidence, correlation, kinetics of release and prognostic value]. / Troponina i cardiaca e troponina T cardiaca nell'angina instabile: incidenza, correlazione, cinetica di rilasciamento e valore prognostico.

BACKGROUND: The aim of this study was to ascertain the incidence of altered serum cardiac Troponin-T (cTnT) and cardiac Troponin I (cTnI) in patients with unstable angina, the concordance between findings for the two proteins, their release kinetics and their utility in predicting coronary events. METHODS: We studied 32 consecutive patients (pts) admitted to the Coronary Unit with a diagnosis of unstable angina; following Braunwald classification criteria, 5 pts were in class I, 4 class II, 23 class III. A blood sample was taken on admission to hospital and subsequently every 8 hours for two days, a total of 7 samples being obtained per pt. Cardiac-TnT values ranging from 0-0.17 mugr/L (Boehringer Mannheim) were considered normal, as were cTnI values ranging from 0 to 0.7 mugr/L (Stratus-Dade). RESULTS: Among 218 samples, altered cTnT values (0.18-0.68 mugr/L) were found in 19 (3 pts), and 13 of these samples were positive for cTnI (0.8-5.5 mugr/L), while the remaining 6 showed borderline values for cTnI (0.5-0.7 mugr/L). No cTnT negative samples were found to be positive for cTnI. The release kinetics of cTnT and cTnI were comparable in all three cases, with a "plateau" pattern, unlike the kinetics in the course of acute myocardial infarction (AMI). The mean follow-up was 13 months on average (range 1-19). In two pts with altered cTnT and cTnI values, symptoms were controlled with medical therapy, while the remaining patient failed to respond to medical therapy and therefore underwent PTCA. Fifteen months later, they are alive and have not had myocardial infarction. Of the 29 pts with normal cTnT and cTnI values, three developed AMI, which in two cases was fatal. Seven pts were submitted PTCA, seven to aorto-coronary bypass surgery, two were subsequently rehospitalized for a recurrent angina symptoms. In 13 pts complete control of symptoms was achieved with medical therapy. CONCLUSIONS: Our findings demonstrate that the incidence of altered cTnT and cTnI values in pts with unstable angina is low; there is close agreement between findings for the two proteins; in cases of angina, the cTnT and cTnI release kinetics are different from those in AMI. The finding of altered cTnT and cTnI values in the serum of our pts with unstable angina does not appear to be of prognostic value for future coronary events.

[The effect of gallopamil on myocardial perfusion in angina of effort]. / Influenza del gallopamil sulla perfusione miocardica nell'angina da sforzo.

To value stress tolerance and stress myocardial perfusion before and after a week of oral therapy with gallopamil 150 mg daily, we studied 10 patients suffering from stable effort angina. We performed bicycle exercise stress testing and thallium scintigraphy (Tl) with planar technique in 3 projections (anterior-posterior and oblique left anterior at 45 and 70 degrees) according to the current standards. We valued systolic and diastolic blood pressure (SBP-DBP), heart rate (HR) and HR-SBP product at rest, at symptoms stress-induced and at the end of the procedure. Moreover we valued work threshold of chest discomfort and ischemia, the maximal work capacity and the perfusion defects according to a Tl score obtained dividing the 3 projections in 5 segments and fixing a value according to the observed perfusion from 0 = normal perfusion to 3 absent perfusion. We observed a significant reduction of basal HR (77 vs 71, p = 0.05), SBP (147 +/- 15 vs 131 +/- 15 mmHg, p = 0.001), DBP (91 +/- 6 vs 83 +/- 6 mmHg, p = 0.002). Work threshold of chest discomfort and ischemia significantly arose (8 +/- 3 vs 11 +/- 4 min., p = 0.002; 6 +/- 3 vs 10 +/- 4 min., p = 0.001). The HR-SBP product at the maximal work capacity and the Tl score significant decreased (31650 +/- 6239 vs 29406 +/- 5418, p = 0.003; 8 +/- 2 vs 5 +/- 1, p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

[Use of myocardial thallium-201 scintigraphy in the evaluation of infarct area]. / Utilizzo della scintigrafia miocardica con Tallio-201 nella valutazione dell'area infartuale.

In twenty-four patients admitted of the Coronary Care Unit for myocardial infarction, without signs of previous necrosis and uncomplicated course, amplitude of infarct size was estimated by 201-Thallium perfusion scintigraphy. The obtained results were compared with residual ventricular function (i.e. angiographic ejection fraction) and with other methods of fibrotic area evaluation such as electrocardiographic score and CPK and CK-MB dismission curve. Concordance was observed among: scintigraphy and ejection fraction, scintigraphy and electrocardiographic score, scintigraphy and CPK peak.

[Intravenously disopyramide phosphate administration for treatment of arrhythmias]. / La disopiramide fosfato endovenosa nella terapia acuta delle aritmie cardiache.

Disopyramide phosphate (DF) was administered intravenously to 50 patients during 55 episodes of arrhythmias. The mean dosage employed was 2 +/- 1.4 mg/kg over a period of 3 minutes to 60 minutes (mean 16 +/- 6'), followed by an infusion at a dose of 0.4 mg/kg/hr in 9 cases. Atrial premature beats were suppressed in 3 of 4 treated cases (75%). Conversion to sinus rhythm was achieved in 4 of 5 (80%) cases of paroxysmal supraventricular tachycardia, unresponsive to vagal maneuvers in 7 of 10 cases (70%) of atrial flutter of recent onset (less than 48 hours) and in 13 of 17 (76%) cases of atrial fibrillation (less than one week in duration). In 9 of 11 cases (81%) with frequent, multiform, repetitive ventricular premature beats and in 7 of 8 cases (87%) of ventricular tachycardia, DF completely suppressed the arrhythmia. The drug increased sinus rate, PR and QRS intervals, but the difference was not statistically significant: the QRS of patients with complete bundle branch block and the QTc interval were significantly prolonged. Severe hypotension was observed in 10 patients after DF i.v., in 5 of whom withdrawal of therapy was deemed to be necessary. Nine other patients had anticholinergic side effects. Our study shows that DF administered i.v. can be used successfully in 75% of supraventricular arrhythmias and in 82% of ventricular arrhythmias.

Sodium nitroprusside in the treatment of Prinzmetal's variant angina.

A patient had attacks of Prinzmetal's angina, resistant to sublingual nitrates in high doses and to a calcium antagonist. All the crises wee resolved by sodium nitroprusside therapy. This report suggests that nitroprusside merits further evaluation in the treatment of Prinzmetal's angina, particularly in cases resistant to usual therapy in which the evolution towards myocardial infarction is very likely.