Papers by armand H piwnica
Thorax, 1978
A case of aneurysm of the main stem of the left coronary artery associated with aortic insufficie... more A case of aneurysm of the main stem of the left coronary artery associated with aortic insufficiency and an aneurysm of the ascending aorta is reported. The importance of coronary angiography in diagnosing this condition is illustrated. Surgical repair included isolation of the coronary aneurysm and replacement of the ascending aorta and aortic valve, combined with triple aortocoronary saphenous vein
Postgraduate Medical Journal, 1976
From 1969 to 1975, 175 patients with acute coronary insufficiency underwent emergency saphenous v... more From 1969 to 1975, 175 patients with acute coronary insufficiency underwent emergency saphenous vein aorto-coronary bypass grafting (SVBG). The patients were divided into two groups: group I, unstable angina (165 patients) and group II, acute evolving myocardial infarction (ten patients). In group I, the hospital mortality was 8-4%, the incidence of post-operative myocardial infarction was 10-3%. Long-term follow-up was obtained
The Thoracic and Cardiovascular Surgeon, 1985
A 24-year-old, 4-months pregnant woman developed an acute thrombosis of a St. Jude Medical aortic... more A 24-year-old, 4-months pregnant woman developed an acute thrombosis of a St. Jude Medical aortic valve prosthesis. Upon admission, she was in cardiogenic shock. A thrombectomy was achieved in emergency under cardiopulmonary bypass. The patient survived but not the fetus. Diagnosis, surgical procedure, anticoagulation drugs and valve prostheses in pregnant women are discussed.
The Journal of Thoracic and Cardiovascular Surgery, 1995
Journal of the American College of Cardiology, 1987
The cardiac myosin phenotype, an important determinant of myocardial contractility, is modified b... more The cardiac myosin phenotype, an important determinant of myocardial contractility, is modified by chronic increases in hemodynamic load. To quantify the proportion of atrial alpha-myosin heavy chain in various types of left atrial overload and to assess the possible relation between this proportion and atrial size, 34 patients were studied , 4 with Wolff-Parkinson-White syndrome, 29 with various types of mitral valvedysfunction and 1 with an atrial septal defect. Four normal autopsy hearts were also studied. The proportion of alpha-myosin heavy chain among total (alpha plus beta) myosin heavy chains was determined in each atrial sample, using an enzyme-linked immunosorbent assay. The size of the left atrium was assessed by one-and two-dimensional echocardiography.
Journal of Molecular and Cellular Cardiology, 1984
The effect of diltiazem during cardioplegic arrest on functional recovery was investigated in iso... more The effect of diltiazem during cardioplegic arrest on functional recovery was investigated in isolated perfused rat heart. The hearts were perfused with Krebs bicarbonate buffer(37~ in working heart mode for I0 min as a baseline hemodynamic variables and underwent infusion of hypothermic K + cardioplegic solution in both the absence(control) and the presence of diltiazem (i x 10-6M) via retrograde perfusion followed by 30 min of cardiac arrest with temperature at 2~ and 15~ respectively. The hearts were then subjected to 30 min of aerobic reperfusion at 37~
Journal of Cardiovascular Pharmacology, 1992
Journal of Cardiothoracic and Vascular Anesthesia, 1993
Journal of Cardiac Surgery, 1989
Pericarbon, a new generation pericardial valve, is characterized by a single, three cuspal shaped... more Pericarbon, a new generation pericardial valve, is characterized by a single, three cuspal shaped pericardium sheet, which is sutured to a second sheet lining the inner surface of the plastic, low profile stent. A coating of hemocompatible carbon film covers all the exposed, nonbiological surfaces. Optimal preservation of collagen and graft cells is achieved by fresh tissue glutaraldehyde fixation and cusp shaping without mold. Accelerated fatigue testing showed a duration of over 150 million cycles, a figure much higher than that observed when current pericardial and porcine valves were tested with the same apparatus. Results of long-term (greater than 7 months, average 10.5) implantation in 20 sheep (13 mitral, 7 tricuspid) disclosed no case of mechanical failure, mild to moderate primary calcification in older explants, and significant fibrous tissue overgrowth only in the tricuspid position. Transmission electron microscopy studies revealed collagen and elastic fiber integrity, no significant plasma protein insudation, and well-preserved graft cells. Re-endothelialization by host cells was a regular finding on scanning electronic microscopy. Early ultrastructural nuclei of calcification were seen mostly on collagen fibers. Pericarbon presents basic changes in pericardial valve design, and optimal morphological preservation is obtained after industrial processing. Accelerated fatigue tests in vitro show long duration. At medium long-term animal experimental follow-up, mechanical failure was not observed; significant host tissue reaction occurred in the tricuspid but not in the mitral position; primary calcification increased progressively with time and involved mainly collagen fibers.
European Journal of Cardio-Thoracic Surgery, 1989
Intraoperative epicardial mapping data obtained in 73 consecutive patients operated upon for the ... more Intraoperative epicardial mapping data obtained in 73 consecutive patients operated upon for the Wolff-Parkinson-White syndrome were reviewed. Fifty-six patients had single and 17 patients had multiple accessory pathways. Except for right free wall pathways, all bypass tracts were divided using an endocardial approach. There were 2 operative deaths, 1 of which occurred after a concomitant mitral valve replacement. A total of 78 of the 87 pathways present in the 71 survivors were successfully ablated (90%). All failures occurred in patients with left posterior septal pathways. Epicardial mapping performed prior to bypass was found helpful in identifying multiple distinct accessory pathways which had been missed preoperatively. This occurred in 6 patients and led to appropriate combinations of classic operative approaches which resulted in all of these pathways being successfully divided. Further, by demonstrating that Kent bundles often presented as multiple closely-spaced or arborized accessory pathways, intraoperative mapping led to widening of the margins of surgical dissection, and in particular to an additional left atriotomy in all cases of left posterior septal accessory pathways which resulted in a substantial improvement in our rate of success.
European Journal of Cardio-Thoracic Surgery, 1989
A long-term experimental morphological study was carried out in 22 adult sheep to evaluate a new ... more A long-term experimental morphological study was carried out in 22 adult sheep to evaluate a new pericardial valve prosthesis (Pericarbon), which had been implanted in the tricuspid or mitral position. This prosthetic device differs substantially from others in that its construction design consists of two sheets of glutaraldehyde-fixed bovine pericardium and a low-profile flexible plastic stent (Delrin) covered by a pyrolytic carbon coated dacron fabric; one pericardium sheet forms the three cusp valve and is sutured to the second, which lines the inner surface of the plastic stent. Twenty animals were sacrificed at fixed intervals, while 2 are still living at about 3 years post-surgery. Tricuspid explants (mean duration, 295 days) showed significant fibrous sheathing and a mean calcium X-ray score of 1.75. Mitral medium-term explants (mean duration, 325 days) had fairly well preserved pliability and a mean calcium X-ray score of 2.5. Long-term explants (mean duration, 467 days) were all stiffened by calcification (mean score, 3.75). None of the explants had tears or perforations. Medium or long-term mechanical failure was not observed. A significant host tissue reaction took place in the tricuspid but not in the mitral position. Calcification mainly involved the collagen fibres and increased progressively with time. Ultrastructural studies invariably disclosed fair preservation of graft tissue structures, surface reendothelization and initial nuclei of calcification within the collagen fibres. These morphological findings confirm the potential advantages of this new prosthetic device and warrant long-term clinical trials to test its actual durability.
European Journal of Cardio-Thoracic Surgery, 1987
Inadequate atrial hypothermia and subsequent ischemic injury have been recognized as the major ca... more Inadequate atrial hypothermia and subsequent ischemic injury have been recognized as the major causes of supraventricular arrhythmias (SVAs) and conduction defects following cold chemical cardioplegia. This study was designed to assess the effects of right atrial cooling (15 degrees-20 degrees C) during cardioplegic arrest upon the incidence of postoperative SVAs and conduction defects in 40 consecutive patients undergoing isolated aortic valve replacement. Atrial preservation was ensured by combining systemic (24 degrees C) and topical hypothermia with snared double caval cannulation during arrest. Myocardial temperatures in the right atrial septum and anterior wall of the right ventricle were recorded before and after each cardioplegic infusion and upon release of caval tapes. Postoperatively, the incidence of SVAs and conduction defects was assessed by continuous rhythm monitoring, bipolar atrial electrograms and, in ten patients, 24-h Holter recordings during the first postoperative day. With the venae cavae snared, temperatures in the right atrial septum were not significantly different from those measured simultaneously in the right ventricle. Release of caval tapes resulted in right atrial temperatures increasing to systemic temperature (from 17.1 +/- 2.9 degrees C to 25.9 +/- 5.6 degrees C [m +/- SD]; P less than 0.01). Atrial rewarming between cardioplegic infusions did not exceed 2.9 degrees +/- 3.2 degrees C. Postoperatively, four patients (10%) developed sustained atrial fibrillation. One additional patient had a single episode of paroxysmal atrial fibrillation and two patients experienced asymptomatic episodes of junctional rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)
European Journal of Cardio-Thoracic Surgery, 1989
Thirty patients have been operated on since July 1986. The mean age was 55 years (range 32-68). T... more Thirty patients have been operated on since July 1986. The mean age was 55 years (range 32-68). Twenty-three simple and 7 double bypasses were performed. The internal mammary artery and 1 prosthetic conduit were used for the 29 left anterior descending (LAD) anastomoses and saphenous vein for the others [5 right coronary artery (RCA), 3 diagonal]. The use of an implantable Doppler probe for continuous monitoring during the 1st postoperative week confirmed patency and gave an estimated flow (mean: 79.23 ml/min, range 43.4). There were no deaths and no cases of infarction or ischaemia, but stress test performance improved. The main advantage of this rapid and safe technique was avoidance of morbidity of extracorporeal circulation (ECC) and limited operative myocardial ischaemia. Criteria of selection were unstable, permanent angina (14); unsuccessful PTCA (8) PTCA and failure (5 emergency cases), redo surgery (4); poor LV function (EF less than 20%) (3); fibrinolytic treatment or severe coagulopathy (2). The ideal patient has severe stenosis with or without retrograde filling of LAD with either RCA or circumflex (which require a lateral thoracotomy).
Cardiovascular Radiology, 1978
This is a case report of a 16-year-old male with moderate mitral disease, probably rheumatic, and... more This is a case report of a 16-year-old male with moderate mitral disease, probably rheumatic, and with severe tricuspid insufficiency, which at surgery appeared to be a congenital malformation of the tricuspid valve (absence of the anterior leaflet). A tricuspid heterograft was successfully inserted. The symptoms of congenital tricuspid insufficiency are discussed, and this entity is differentiated from other causes of tricuspid insufficiency.
ASAIO Journal, 1992
The design criteria leading to the development of a new bileaflet valve (Sorin Bicarbon) were der... more The design criteria leading to the development of a new bileaflet valve (Sorin Bicarbon) were derived from the analysis of functional requirements, the performance of existing prostheses, and the availability of an advanced carbon coating technology (Carbofilm). The hinge is the critical element affecting fluid dynamics, durability, and thrombus formation in bileaflet valves. A comparative study of three existing models led to a new hinge design that was based on coupling two spheric surfaces with different radii of curvature (leaflet pivot and hinge recess) and obtained by electroerosion into a Carbofilm-coated metallic housing. In this valve, the point of contact moves continuously by rolling, not sliding. This minimizes friction and wear and allows uninterrupted washing of the blood exposed surfaces even during diastole (a finding established in patients using transesophageal echocardiography). Tricuspid implantation without anticoagulation in 33 sheep did not lead to thrombotic events (follow-up, 40-400 days). In the first 36 clinical implants observed for 15 months (mitral position, size 29; two unrelated deaths), the mean diastolic gradient by echo Doppler was 4 +/- 1.25 mmHg; the functional area was 3.2 +/- 0.6 cm2. No leaflet fracture and no thrombotic or embolic complications were observed clinically using a standard anticoagulant regimen.
The Annals of Thoracic Surgery, 1992
The Annals of Thoracic Surgery, 1992
The enthusiastic clinical reports on normothermic blood cardioplegia contrast with the paucity of... more The enthusiastic clinical reports on normothermic blood cardioplegia contrast with the paucity of data on the myocardial metabolic effects of this technique. The present study was therefore designed to assess whether normothermic blood cardioplegia really provides an aerobic environment during aortic cross-clamping. Thirty-one patients undergoing coronary (16 patients), valve (13 patients), and transplantation (2 patients) procedures were given continuous normothermic blood cardioplegia through the coronary sinus. Myocardial metabolism was assessed either immediately before aortic unclamping (16 patients) by collecting blood simultaneously from the cardioplegia infusion line and the aortic effluent or during reperfusion (15 patients) by collecting blood simultaneously from the radial artery and the coronary sinus. All samples were assayed for markers of anaerobiosis (blood gases, lactates), leukocyte activation (elastase), and lipid peroxidation (malondialdehyde, vitamin E). At the end of arrest, oxygen extraction was low, whereas the production of lactates was small, thereby suggesting the efficacy of normothermic blood cardioplegia in maintaining a predominantly aerobic metabolism. This was confirmed by postarrest data, as oxygen extraction measured immediately after cross-clamp removal was unchanged from prearrest values, whereas lactate metabolism yielded transient and limited production followed by prompt recovery of normal extraction patterns. There was no release of elastase from the myocardium, which suggests adequate protection of the coronary endothelium from ischemic injury and the related increase in leukocyte activation. Likewise, postarrest coronary sinus concentrations of malondialdehyde and vitamin E were identical to the respective arterial concentrations, thereby ruling out the occurrence of intramyocardial lipid peroxidation at the time of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)
The Annals of Thoracic Surgery, 1993
Peripheral vasodilation is commonly seen during and after warm heart operations and can become of... more Peripheral vasodilation is commonly seen during and after warm heart operations and can become of clinical concern when it requires vasopressors because some of these drugs adversely affect coronary artery bypass graft flows. As hemodilution lowers systemic vascular resistance, we assessed whether peripheral vasodilation could be limited by a drastic reduction of the volume of infused cardioplegia. Fifty patients underwent isolated coronary artery bypass grafting procedures using normothermic (35' to 37°C) bypass and normothermic continuous retrograde blood cardioplegia. They were divided into two equal groups: in group 1, blood was diluted 4:l with hyperkalemic crystalloid cardioplegia, whereas in group 2, the cardioplegic "solution" was limited to the sole arresting agents that were concentrated in a small volume (16 mEq potassium chloride and 3 mEq magnesium chloride in a 20-mL ampoule). This "minicardioplegia" was continuously added to arterial blood so as to keep the heart arrested. The average volume of cardioplegia per patient was 1,000 mL in group 1 and arm heart operation is a recently introduced technique that combines normothermic cardiopulmonary bypass and normothermic continuous blood cardioplegia [I, 21. Whereas several investigators have assessed the consequences of this new type of cardioplegia on myocardial preservation, there has been no detailed study, except for that of Christakis and co-workers [3], addressing the issues raised by the systemic effects of normothermic cardiopulmonary bypass.
The Annals of Thoracic Surgery, 1985
This study was designed to assess whether an oxygenated fluorocarbon solution could reduce ischem... more This study was designed to assess whether an oxygenated fluorocarbon solution could reduce ischemic brain damage related to arterial air embolism. Air embolism was produced by injecting air bubbles into the carotid artery of barbiturate-anesthetized rats breathing 100% oxygen. Results were assessed on electrocorticogram.
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Papers by armand H piwnica