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Biomedical subjects

M Chiavarelli

Publications and source records attributed to M Chiavarelli.

31 records · Page 2Linked to original sources
PubMed1987

Right ventricular outflow construction without cardiopulmonary bypass.

Establishment of right ventricular-pulmonary arterial continuity without the use of cardiopulmonary bypass was undertaken in 36 patients with different anomalies associated with pulmonary atresia or severe stenosis. Hospital mortality was 11% with no late death. Fourteen of the 27 individuals with pulmonary atresia, ventricular septal defect, and hypoplastic confluent pulmonary arteries had adequate angiographic follow-up, which demonstrated significant pulmonary artery enlargement. Five patients underwent total correction, two after unifocalization operations to establish lobar pulmonary arterial continuity. Symmetric growth of the left and right pulmonary artery was not achieved. However, the enlargement was adequate for potential final repair in all the patients with an unrestricted outflow tract.

Blood Vessel Prosthesis↗
PubMed1987

Modifications of the Fontan operation applicable to patients with left atrioventricular valve atresia or single atrioventricular valve.

Two modifications of the Fontan operation are proposed for prevention of pulmonary venous obstruction in patients with left atrioventricular valve atresia or single atrioventricular valve. In the first technique, a bipedicled flap of right atrial wall is used to separate systemic and pulmonary venous drainages; an atriopulmonary connection is constructed by use of the right atrial appendage, and the defect in the right atrial wall is repaired with a pericardial patch. In the second technique, the superior vena cava is transected and the cardiac and cephalad ends are anastomosed separately to the pulmonary arterial confluence. A patch is positioned inside the right atrium to separate the systemic from the pulmonary venous drainage. Both techniques achieve unrestricted systemic and pulmonary venous channels. Severe atrial arrhythmias, present in the four patients operated on with the first procedure, were not seen in 12 patients who had repair with the second procedure.

Heart Atria↗
PubMed1986

Calcium entry blockers and cardioplegia: interaction between nifedipine, potassium, and hypothermia.

The potential additive protective effect provided by nifedipine to the University of Alabama Hospitals cardioplegia solution (ACS) was assessed with the use of a guinea pig heart-lung model of cardiopulmonary bypass and ischemic arrest. The addition of nifedipine consistently enhanced the protective properties of ACS infused at 37 degrees C; functional recovery was similar to that observed with cold ACS. Despite the additional protection under normothermic conditions, nifedipine did not improve recovery after infusion at 4 degrees C. The abolition by hypothermia of the protective effects of nifedipine suggests a similarity in action between nifedipine and hypothermic protection. The interaction between ACS and nifedipine was studied on bovine coronary arteries in vitro. Nifedipine caused a marked reduction in the coronary vasoconstricting effect of ACS, both under normothermic and hypothermic conditions. The use of nifedipine in cardioplegia may provide additional protection when uneven distribution of the cardioplegic solution is expected and hypothermic protection is unreliable.

Animals↗
PubMed1985

Interactions between pharmacological cardioplegia and hypothermia for intraoperative myocardial protection.

Cold cardioplegia is currently the method of choice for providing myocardial protection during open-heart surgical procedures. Two components of protection, perfusion cooling and pharmacological cardiac arrest, were investigated in the guinea pig heart-lung model. The effects of two cardioplegic solutions, the University of Alabama Hospital solution and the St. Thomas' Hospital solution, and a control perfusate were compared. The results confirmed the efficacy of hypothermia as a protective agent and the additional protection afforded by pharmacological cardioplegia. Infusion temperature critically influenced the cardioprotective action of the Alabama solution: Striking protection was afforded only under hypothermic conditions, whereas myocardial damage was exacerbated by the infusion at 37 degrees C. The St. Thomas' Hospital solution provided substantial protection independent of infusion temperature. Thus, the safety margin of the Alabama solution was narrower than that of the St. Thomas' solution. It is suggested that the difference between the two cardioplegic solutions partially depends on their coronary vasoactivity, since the administration of the Alabama solution at 37 degrees C increased coronary perfusion pressure. It would seem worthwhile to use a temperature-independent cardioplegic solution devoid of coronary vasoconstricting action.

Animals↗
PubMed1983

[Effects of cardioplegic solutions on coronary and myocardial ultrastructure. Preliminary note].

Ultrastructural changes of the myocardium and the coronary arterial endothelium were studied following cold perfusion with two different cardioplegic solutions (CPS) (the University of Alabama and the St. Thomas Hospital solutions), and with Krebs' solution as a control (CS). Guinea pig heart-lung preparations (HLP) were subjected to cardiac arrest by perfusion under CPS or CS (4 ml/Kg/min. X 4 min.). The duration of the cardiac arrest was 60 minutes, and additional amounts of cold solution were perfused after the first 30 minutes. In a second experimental group, HLP were reperfused with blood following 60 minutes of cardioplegic arrest, and maintained under full activity for the next 30 minutes. At the end of the study, specimens of coronary artery and myocardium were obtained and observed by Scanning (SEM) and Trasmission (TEM) electron microscopy. All the specimens were compared with additional specimens obtained from control hearts not subjected to cardiac arrest. The myocardial ultrastructure of hearts arrested with CPS was well preserved, whereas severe myocardial damage, consisting in the absence of glycogen granules, intracellular edema and myofibrillar contraction, was following CS-induced cardiac arrest. In contrast, perfusion with the St. Thomas CPS produced severe vascular damage, characterized by interruption of the endothelial layer, and bulging of endothelial cells into the lumen; no vascular changes were observed following cardiac arrest with CS or Alabama CPS. We conclude that the damage to the coronary arterial endothelium is not related to cardiac arrest, or to perfusion with cristalloid solution, or to myocardial damage, but appears to depend on the composition of the CPS.

Animals↗
PubMed1982

Prostacyclin can either increase or decrease heart rate depending on the basal state.

1 The influence of the basal heart rate on the change in rate induced by prostacyclin (PGI2) was investigated in beagles anaesthetized with chloralose. 2 In male dogs with a low basal heart rate (less than 100 beats/min) PGI2, in doses up to 0.5 microgram/kg intravenously, induced hypotension and tachycardia. 3 In contrast, PGI2-induced hypotension was accompanied by bradycardia when either the basal heart rate was increased (greater than 130 beats/min) with isoprenaline or nitroprusside, or the dose of PGI2 was increased. 4 Female beagles were less sensitive than males to the stimulation of a reflex bradycardia by PGI2. 5 The influence of prostaglandin E2 (PGE2) and bradykinin on heart rate was also found to depend upon the basal state in some dogs. 6 Bilateral vagotomy reversed the bradycardia provoked by PGI2, PGE2 and bradykinin. 7 Thus, PGI2-induced bradycardia in dependent on both the dose and the basal heart rate. Similarly the effects of PGE2 and bradykinin on heart rate also depend upon the basal state in some dogs. Moreover, there is a correlation between the ability of all three agonists to induce bradycardia, suggesting a common mechanism of action.

Animals↗
PubMed1982

Effects of cardioplegic solutions on conductive coronary arteries.

The effects of two cardioplegic solutions (CPSs) on isolated, superfused, bovine coronary arteries were compared with those produced by changes in composition of standard Krebs medium. High potassium, low sodium content or the addition of albumin produced vasoconstriction; high magnesium, high glucose content or the addition of mannitol led to vasodilatation. In most cases hypothermia slightly reduced vasoconstriction and enhanced vasodilatation. The action of the two CPSs is the result of the interaction of these basic effects. The results suggest that the vasomotor reactions of coronary arteries to CPS may affect the delivery of the CPS to the myocardium and exert a critical influence on successful cardioplegia.

Animals↗
PubMedDate not supplied

Pleural drainage after repair of tetralogy of Fallot.

Prolonged pleural effusion after congenital heart surgery results in extended hospitalization. Pleural drainage was evaluated in 39 consecutive patients undergoing repair of tetralogy of Fallot, to identify risk factors for persistent pleural effusion. Duration and amount of drainage was examined by the Kaplan-Meier method and risk factors were evaluated by univariable and multivariable analyses. Median time of pleural drainage was 6.1 days, range 3 to 42 days. Duration of pleural drainage correlated with length of hospital stay (p < 0.0001). Postrepair right atrial pressure (p = 0.018) and preoperative hemoglobin (p = 0.035) were risk factors for persistent drainage. The presence of a previous right thoracotomy reduced drainage duration (p = 0.034). Prolonged mechanical ventilation increased the average daily volume of effusion (p < 0.0001). In conclusion, prolonged pleural effusion is an important morbidity factor after repair of tetralogy of Fallot. Bilateral chest tube insertion is indicated in patients with high preoperative hemoglobin and elevated postrepair right atrial pressure. Right thoracotomy is the preferred surgical approach when a preliminary palliative shunt is required.

Adolescent↗
PubMedDate not supplied

Experimental cardiomyopathy as a model of chronic heart failure.

End-stage heart disease is a major health care issue and it represents one of the most costly diseases. Several experimental heart failure models have been developed; however, a single model is not widely accepted as representative of clinical heart failure. The doxorubicin-induced cardiomyopathy model was used in the current study to address two issues: 1) to define a standardized dose regimen of intracoronary doxorubicin infusion; and 2) to establish a method of determining the onset and time course of heart failure. Twenty dogs underwent placement of an intracoronary catheter. A total dose of 1 mg/kg of intracoronary doxorubicin was infused. Hemodynamics were obtained at weeks 0, 7, and 12. Echocardiography was performed weekly. Right and left ventricular biopsy specimens were examined at weeks 0 and 12. Survival after doxorubicin-induced cardiomyopathy was 60% at week 12. The development of heart failure was demonstrated by a significant decrease in left ventricular ejection fraction and cardiac index and a significant increase in left ventricular end-diastolic pressure and volume. The leukocyte count, hemoglobin, and hematocrit decreased significantly. Histologic changes of both the right and left ventricular myocardial biopsy specimens included myocellular hypertrophy, loss of myofibrillar material, and vacuolization. Intracoronary doxorubicin reliably produced an experimental model of accelerated heart failure that developed over the course of 12 weeks. Echocardiographic monitoring allowed a close surveillance of heart failure development. This model may be useful to evaluate the efficacy of cardiomyoplasty, mechanical assist devices, transplantation, and reduction ventriculoplasty.

Animals↗
PubMedDate not supplied

Recurrent right atrial thrombus after repair of ruptured sinus of valsalva aneurysm.

Ruptured sinus of Valsalva aneurysm is a rare cardiac abnormality. Early surgical repair is indicated to prevent complications such as heart failure, infective endocarditis, arrhythmias, and thromboembolic events. The authors report an unusual case of recurrent right atrial thrombus after the surgical repair and closure of ruptured sinus of Valsalva aneurysm.

Adult↗
PubMedDate not supplied

Cardiac transplantation for infants with hypoplastic left-heart syndrome.

OBJECTIVE: To determine whether cardiac transplantation improves the natural history of infants with hypoplastic left-heart syndrome and to examine differences in outcome as a function of the pretransplant period. DESIGN: Retrospective cohort study. Historical, clinical, and laboratory data were collected during the pretransplant period, the in-hospital period, and for up to 6 years following transplantation. Data were analyzed using the product-limit estimate and the log rank test. SETTING: A tertiary, acute care, university teaching hospital. PATIENTS: All 111 infants with hypoplastic left-heart syndrome who entered and completed a protocol leading to transplantation from November 19, 1985, to December 31, 1991. Infants who died while waiting for transplantation were included. INTERVENTION: Orthotopic cardiac allotransplantation. MAIN OUTCOME MEASURES: Pretransplant waiting mortality and its influence on posttransplant survival, operative (in-hospital or within 30 postoperative days in discharged patients) and intermediate-term mortality (5 years), and reoperation rates for cardiac surgery. RESULTS: Transplantation procedures were performed in 84 infants (76%; 95% confidence interval [CI], 66% to 83%) ranging in age from 3 hours to 151 days. Twenty-seven infants registered for transplantation died while awaiting a donor heart. Operative mortality was 13% (CI, 7% to 23%), and 69 patients were late survivors (62% [CI, 52% to 71%] of the study group and 82% [CI, 72% to 89%] of the transplant recipients). Overall 5-year actuarial survival was 61% (CI, 52% to 70%). Transplant recipients had a 5-year survival of 81% (CI, 71% to 88%). Freedom from reoperation was 89% (CI, 76% to 95%) at 5 years. CONCLUSIONS: Cardiac transplantation for hypoplastic left-heart syndrome has a significant positive impact on the natural history of this uniformly lethal lesion.

Cohort Studies↗