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Biomedical subjects

R Dion

Publications and source records attributed to R Dion.

At least 73 records · Page 4Linked to original sources
PubMed1994

[Thrombus of the right atrium simulating myxoma in primary antiphospholipid syndrome].

Various thrombo-embolic complications have been related to the antiphospholipid syndrome. The authors report the case of a patient with a primary antiphospholipid syndrome associated with a right auricular mass highly suggesting a myxoma by both echocardiography and nuclear magnetic resonance imaging. Meanwhile, the histological examination of the operative specimen showed a well organized and calcified thrombus. Intracardiac thrombus has been rarely reported as a complication of the antiphospholipid syndrome. The preoperative investigations can't differentiate such a thrombus with a myxoma and the diagnosis is usually made postoperatively.

Antiphospholipid Syndrome↗
PubMed1994

Isolation of the left coronary artery ostium by an aortic cusp attachment: a rare cause of myocardial ischemia.

A 34-year-old woman experienced a 3-month history of recurrent chest pain on exertion. Extensive investigation, including coronary angiography, revealed severe aortic incompetence with suspicion of single-vessel coronary disease. At operation the aortic valve was tricuspid but the left coronary cusp was adherent to the aortic wall, resulting in isolation of the left coronary artery with only a tiny communication with the aortic lumen. The three cusps were excised. An aortic valve replacement was performed with an aortic homograft. The postoperative course was uneventful and myocardial ischemia was totally relieved.

Adult↗
PubMed1994

The use of somatosensory evoked potentials to determine the optimal degree of hypothermia during circulatory arrest.

We sequentially recorded subcortical (P14) and cortical (N20) somatosensory evoked potentials (SEPs) in 32 patients undergoing deep hypothermic circulatory arrest (CA). Under normal hemodynamic conditions, hypothermia initially produced N20 disappearance at a mean nasopharyngeal temperature of 20.4 +/- 2.6 degrees C (range 14.5 to 26.1 degrees C) and P14 disappearance at a mean of 16.9 +/- 2.0 degrees C (range 12.4 to 20.2 degrees C). On rewarming, P14 reappeared at mean temperature of 19.3 +/- 4.0 degrees C (range 13.5 to 29.2 degrees C) and N20 at a mean of 21.1 +/- 4.1 degrees C (range 14.3 to 29.6 degrees C). The delay of SEP reappearance after restoration of blood flow correlated significantly with CA duration (r = 0.74 for P14, and r = 0.62 for N20; p < 0.01). Neurological recovery was uneventful in 23 patients; 5 patients presented with neurological sequelae (minor or transient in 4; no recovery from anesthesia and death after 48 hours in 1), and 4 patients died during operation. Twenty-three of 24 surviving patients in whom P14 disappearance was the criterion that hypothermia was deep enough to perform CA (duration: 17 to 94 min) had a normal neurological outcome. By contrast, all surviving patients in whom cortical SEPs disappeared at higher temperatures presented neurological sequelae. In conclusion, the neurophysiological monitoring of brain stem activity, as specifically provided by SEPs, enables determination of the optimal temperature for CA, and demonstrates superiority of SEP monitoring over the use of EEG.

Adult↗
PubMed1994

Differences in vasoreactivity between gastroepiploic artery grafts late after bypass surgery and grafted coronary arteries.

BACKGROUND: The gastroepiploic artery is increasingly used as an alternative arterial coronary bypass conduit. In vitro studies have reported differences in vasoreactivity among various types of coronary graft conduits, susceptible to influencing the adaptation of myocardial blood flow and long-term patency rate. METHODS AND RESULTS: To evaluate in vivo the vasoreactivity of gastroepiploic artery grafts implanted long-term, nine angiographically smooth grafts implanted to the distal right or to the left circumflex coronary artery were studied with quantitative angiography 6 to 36 months after surgery. Angiograms were obtained on 35mm cinefilms in basal conditions, after injection of methylergometrine (0.4 mg IV), and after intragraft injection of 1 mg isosorbide dinitrate. In basal conditions, there was no difference in luminal diameter between gastroepiploic and coronary arteries (1.64 +/- 0.32 versus 1.51 +/- 0.31 mm; P = NS). After methylergometrine, a constriction was observed in all gastroepiploic artery grafts (-14 +/- 6% of basal diameter) and in all but one grafted coronary artery (-6 +/- 5%). After isosorbide dinitrate, a dilation was consistently observed in all gastroepiploic artery grafts (+26 +/- 9%) and grafted coronary arteries (+14 +/- 7% of basal). Changes in lumen diameter in response to these constrictor and dilator stimuli, either expressed in absolute values or in percentage of control were significantly greater (P < .001) in gastroepiploic artery grafts than in grafted coronary arteries. CONCLUSIONS: Gastroepiploic artery grafts implanted long-term are more reactive than grafted coronary arteries to ergometrine and nitrates. This response differs from that previously reported of internal mammary artery grafts to the same pharmacological vasoactive stimuli. This suggests that the concept of a more efficient endothelium-dependent control of vasomotor tone contributing to better long-term functional results of internal mammary artery grafts cannot be directly extrapolated to gastroepiploic artery grafts.

Arteries↗
PubMed1993

Bilateral mammary grafting. Clinical, functional and angiographic assessment in 400 consecutive patients.

Between October 1985 and September 1991, 400 patients benefited from bilateral internal mammary artery (BIMA) grafting. Of these, 354 (88.5%) were male and the average age was 57.4 years. There were 132 (33%) urgent procedures, 55 in diabetic patients (14%) and 15 in end-stage renal failures (4%). An average of 3.9 distal anastomoses (AN) per patient was undertaken, 2.8 using arterial grafts. Two hundred sixty-nine patients (67.2%) received exclusively arterial grafts. Right internal mammary artery (RIMA) grafts were predominantly directed to the left coronary system (348 AN = 78%) and particularly to the circumflex (CX) area. Postoperative myocardial infarction was diagnosed in 16 patients (4%). Reoperation was required for early myocardial ischemia in 12 patients (3%) and for excessive bleeding in 23 patients (5.8%). Sternal complications occurred in 18 patients (4.1%), 5 in diabetic patients (9%) and 3 in renal patients (20%). The hospital mortality was 2% (8 patients, 3 cardiac causes). Follow-up averages 37.7 months. Late mortality was 3% (12 patients, 4 cardiac causes). Angina recurred in 12 patients (3.1%). The maximal stress test at a mean interval of 9 months was abnormal in 7.4% (21 patients). One hundred eighty-one patients (47%) consented to an angiographic restudy at an average of 13 months postoperatively. Pedicled RIMA patency rates equal those of pedicled LIMA (95.1 vs 96.7, NS) and the grafted vessel does not alter the patency rates of IMA AN. A pedicled IMA graft is preferable to a free IMA graft (96.1 vs 79.6, P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Somatosensory evoked potentials in patients undergoing circulatory arrest under profound hypothermia].

The surgical repair of ascending aorta aneurysms can only be carried out under total circulatory arrest, and is consequently to be performed under deep hypothermia, in order to adequately decrease the metabolic requirements of the brain. However, the optimal temperature to be reached is poorly known. SEPs to median nerve stimulation were recorded in 21 operations performed in 20 patients undergoing profound hypothermia. The latencies of all SEP components increase to 21 degrees C. Waves N20 and P14 disappear at mean naso-pharyngeal temperatures of 20 degrees C and 17 degrees C, respectively, although a wide inter-individual variability was observed. We suggest to use the P14 disappearance as the criterion to perform the circulatory arrest: in fact, all surviving patients in whom this criterion was fulfilled recovered without any detectable neurological sequellae, while three patients in whom brain activities disappeared independently on body temperature presented with neurological sequellae. Moreover, particularly if patients presenting with ischemia-induced disappearance of Erb's point activities were excluded, we found a significant correlation between the duration of the circulatory arrest and the delay of N20 and P14 reappearance on rewarming. This confirms the importance of sufficient hypothermia, on the one hand; and on the other hand, our findings imply that, even if SEP monitoring considerably decreases the risk of neurological sequellae associated with these operations, the duration of the circulatory arrest should be reduced as far as possible.

Adult↗
PubMed1993

Ischemic mitral regurgitation: when and how should it be corrected?

True and significant ischemic mitral regurgitation affects on average 4% of the patients undergoing coronary bypass surgery. It not corrected, it profoundly influences the hospital mortality and the five year survival, even in the case of satisfactory myocardial revascularization. It is found predominantly in cases of right coronary and/or circumflex disease, and results mostly from restricted leaflet motion rather than from prolapse. Mitral annulus dilatation is present in all cases, and is the only mechanism of regurgitation in 50% of the patients. The indication for a valve procedure usually rests on findings at heart catheterization (i.e. the ratio of regurgitant/forward stroke volume, LV end-systolic volume index), but may be refined by pre- and perioperative transesophageal echocardiography; the LV volume loading test is very helpful in taking the decision in case of moderate or intermittent regurgitation. Mitral valve annuloplasty will easily and expeditiously correct or decrease the regurgitation in the majority of cases. If the mitral valve has to be replaced, the surgeon should always try to keep the papillary muscle-annulus continuity, at least posteriorly.

Chordae Tendineae↗
PubMed1992

Selectivity scale of calcium antagonists in the human cardiovascular system based on in vitro studies.

The inhibitory effect of calcium antagonists has been studied on the calcium signal and on contractile activity in the human coronary and internal mammary arteries. We observed that rhythmic vasospasms, either spontaneous or evoked by serotonin and endothelin, were highly sensitive to calcium-channel inhibitors. Functional parameters describing the inhibition have been compared to binding parameters estimated in radioligand studies on membranes prepared from human coronary artery and from human heart. Taking the present studies and observations already published together, it was possible to build up a selectivity scale for diltiazem, verapamil, nifedipine, and nisoldipine. This showed that nisoldipine was more selective for coronary artery than the other calcium antagonists so far studied. Such a selectivity observed in functional studies on intact human preparations in vitro could be predicted considering the kinetic parameters of the interaction of nisoldipine with calcium channels.

Calcium↗
PubMed1992

Use of the Carpentier-Edwards porcine bioprosthesis: assessment of a patient selection policy.

The Carpentier-Edwards bioprosthesis was implanted in 369 patients (414 valves) between May 1977 and December 1987 (age 67.2 +/- 0.5 years); 242 had aortic valve replacement, 80 had mitral valve replacement, 44 had multiple valve replacement, of which 41 were aortic and mitral valve replacement, 2 had isolated tricuspid valve replacement, and 1 had a pulmonary valve replacement. The selection criteria were the following: shorter life expectancy (253 patients) or contraindications to anticoagulants for organic (113 patients) or psychologic (38 patients) reasons, or both. The early mortality rate was 11.1% (aortic valve replacement, 9.1%; mitral valve replacement, 12.4%; aortic and mitral valve replacement, 23.1%). Total cumulative follow-up was 1456 pt-yr (mean 4.4 years, range 1 to 148 months), and the patient evaluation was 99.5% complete. Late mortality was 4.9%/pt-yr. Five-year survival was 70.4% +/- 2.7% overall, 74.3% +/- 3.2% after aortic valve replacement, 60.9% +/- 6.2% after mitral valve replacement (p < 0.03), and 60.7% +/- 8.1% after aortic and mitral valve replacement. Eight patients were reoperated on for primary tissue failure, and freedom from reoperation for structural valve deterioration was 97.5% +/- 1.2% at 5 years and 95.6% +/- 1.8% at 8 years. Failing aortic bioprostheses were explanted in four patients (0.4%/pt-yr) and mitral bioprostheses in seven (1.6%/pt-yr). No patient whose valve was inserted after the age of 70 had to be reoperated on for structural valve dysfunction. The probability of freedom from thromboembolism after 5 and 8 years of follow-up was 93.1% +/- 1.6% and 92.2% +/- 1.8%, respectively. The prevalence of anticoagulant-related hemorrhage was 0.8%/pt-yr (major 0.6%, minor 0.2%). Anticoagulants had to be maintained in 16.3% of the patients: 5.9% after aortic valve replacement, 35.7% after mitral valve replacement, and 45.8% after aortic and mitral valve replacement, while 80.0% were on a regimen of antiplatelet drug therapy. Prosthetic valve endocarditis happened in five patients (0.3%/pt-yr). Freedom from all valve-related morbidity and mortality, including hospital deaths, was 71.0% +/- 2.7% at 5 years and 58.6% +/- 4.6% at 8 years and was significantly better in the aortic valve replacement group (61.3% +/- 6.6% at 8 years) compared with the mitral valve replacement group (54.4% +/- 7.7% at 8 years; p = 0.04). This study confirms the satisfactory performance of the Carpentier-Edwards valve after aortic valve replacement in elderly patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Aged↗
PubMed1992

Use of the inferior epigastric artery for coronary bypass.

Between December 1988 and April 1991, 74 free inferior epigastric arteries were used in 73 patients for coronary artery bypass grafts. In addition, 72 of the patients received a left internal mammary artery for single or sequential grafting to the left anterior descending system and 62 a right internal mammary artery to the circumflex or the right coronary artery. Twenty-seven patients had no saphenous vein available, and two had no suitable internal mammary artery; in an attempt to make a complete arterial revascularization, we chose the inferior epigastric artery as an alternative conduit in 24 young patients and in 10 reoperations; bilateral internal mammary artery dissection was avoided in four patients with impaired lung function and in six patients with selected two-vessel disease to spare one internal mammary artery. The technique for harvesting the inferior epigastric artery is described. Fifty-three inferior epigastric artery grafts were anastomosed to the distal right coronary artery or to its branches, 18 to the distal obtuse marginals of the circumflex artery (three as sequential grafts and one as a natural Y graft), and three to the left anterior descending system. The mean number of distal anastomoses is 3.60 per patient. Seventy proximal anastomoses of the inferior epigastric artery were made to the aorta and four to one internal mammary artery. There were four early deaths and one nonfatal myocardial infarction. Four abdominal wound hematomas needed surgical drainage. Sixty-one patients underwent angiographic study on postoperative day 10:59 of 61 inferior epigastric artery grafts (63 of 65 inferior epigastric artery distal anatomoses) and 111 of 111 internal mammary artery grafts (155 of 156 internal mammary artery distal anastomoses) were patent. Clinical follow-up of all the survivors (100% follow-up) could be obtained with a mean period of 9 months (1 to 28 months). There was no late cardiac death, no infarction, and all the patients were free of angina. Nineteen patients underwent a 6-month postoperative angiographic study. Seventeen of 19 inferior epigastric artery grafts were patent and 16 of 19 were intact; 34 of 34 internal mammary artery grafts (46 of 47 internal mammary artery distal anastomoses) were patent and intact. In conclusion, free inferior epigastric artery grafts can reach the diaphragmatic ischemic areas of the heart. The early patency rate and the clinical results are encouraging but only long-term evolution and evaluation can determine the true efficacy of the inferior epigastric artery graft as a reliable conduit for coronary artery bypass graft operations.

Abdominal Muscles↗
PubMed1991

[Myocardial revascularization with internal mammary artery graft: analysis of early and late post-operative respiratory morbidity].

To evaluate the respiratory morbidity resulting from myocardial revascularization with internal mammary artery (IMA) graft, we reviewed 153 patients operated on between April and November 1988. There were 124 men with a mean age of 61 years. A bilateral IMA graft was used in 30 patients (20%). During the harvesting of the mammary graft, the homolateral pleura was systematically opened. Acute respiratory failure was more frequent in patients with bilateral IMA (13%) than in patients with unilateral IMA graft (3%) (p less than 0.05). Consequently, the mean duration of mechanical ventilation was longer in patients with bilateral IMA graft: 56 versus 23 hours (p less than 0.05). Lung volume measurements were altered according to a restrictive pattern. On the 9th post-operative day, forced vital capacity was reduced to 59.6% of the pre-operative value in patients with unilateral IMA and to 47.1% in patients with bilateral IMA graft (p less than 0.001). Late results were obtained in 111 patients. After a mean follow-up of 7 months, forced vital capacity was still reduced to 86.8% of the pre-operative value in patients with single IMA and to 78.1% in patients with bilateral IMA graft (p less than 0.001). In conclusion, respiratory morbidity is not negligible. Bilateral IMA grafting should generally be reserved to young patients (less than 65 years) with normal pre-operative pulmonary function tests.

Adult↗
PubMed1991

Flow-induced vasomotor response to tachycardia of the human internal mammary artery and saphenous vein grafts late following bypass surgery.

Increasing blood flow results in endothelium-dependent vasodilation of angiographically normal epicardial coronary arteries in humans. To compare the ability of internal mammary artery (IMA) and saphenous vein (SV) used as coronary artery bypass grafts to adapt their vasomotor tone to an increase in myocardial blood flow demand induced by tachycardia, 10 IMA and seven SV grafts were studied by quantitative angiography more than 6 months (range, 6-82 months) after surgery in 17 patients. All grafts were angiographically smooth and implanted to large nonakinetic perfusion zones. Angiograms were obtained in basal sinus rhythm (71 +/- 10 beats/min), during atrial pacing (129 +/- 9 beats/min), and after intragraft infusion of 1 mg isosorbide dinitrate (ISDN). In basal sinus rhythm, the cross-sectional area of SV was superior to that of IMA (10.7 +/- 3.6 versus 5.4 +/- 1.7 mm2; p less than 0.01). All IMA dilated during pacing (+14.8 +/- 11.5%; p less than 0.005) and a further increase in IMA cross-sectional area occurred after ISDN (+27.4 +/- 20.1% versus basal; p less than 0.005). In contrast, SV failed to dilate during pacing (+0.3 +/- 5.4%; p = NS) and after ISDN (+0.7 +/- 6.0% versus basal; p = NS). Thus, an increase in myocardial blood flow demand induced by tachycardia results in dilation of IMA but not of SV grafted on coronary vessels. The ability of the endothelium to modulate the vasomotor tone of IMA grafts in response to changes in blood flow could contribute to their excellent long-term functional results after coronary artery bypass surgery.

Adaptation, Physiological↗
PubMed1991

Myocardial revascularization in patients on renal replacement therapy.

Coronary disease is the main cause of mortality and morbidity among long-term survivors on renal replacement therapy (RRT). Despite the additional risk factors, myocardial revascularization has been recently attempted with various success in some patients on RRT. We report on 26 patients (13 dialyzed and 13 transplanted, mean age: 50 years [range 38-66]) who have undergone either surgical aorto-coronary bypass (CABG) (n = 16) with mammary artery grafts, or percutaneous coronary angioplasty (PTCA) (n = 9), or both procedures (n = 2). Indication was angina pectoris in all but three patients with painless ischemia. Eight patients had unstable angina (NYHA class IV). A previous myocardial infarction was documented in 11 cases. Coronary angiography disclosed mainly multiple vessel disease (81%). Post CABG complications consisted of severe intrathoracic bleeding (n = 3) resulting in death in 2 cases. PTCA entailed no major complication. After the critical postoperative period, the long-term survival was the same as that of non-uremic patients and the clinical improvement, according to the NYHA classification, was highly satisfactory at 6 months and persists up to 2 years. We conclude that coronary angiography and myocardial revascularization should be considered in patients on long-term RRT developing coronary disease.

Adult↗
PubMed1991

[Revision of midline sternotomies after cardiac surgery in 1988: retrospective study].

Twenty-three of 514 (4.6%) patients who underwent cardiac surgery in 1988 with cardiopulmonary bypass were later reoperated for sternal complications. Several risk factors, including pre-, intra and postoperative variables, have been investigated. A significant correlation was found with the presence of diabetes mellitus, the type of operation (bilateral internal mammary artery grafting), early reoperations, haemodynamic alterations, pulmonary infections and incidence of serious non infectious complications. The different sternal complications are analyzed from a clinical and therapeutic point of view.

Aged↗