Biomedical subjects
Publications and source records attributed to H De Geest.
Four cases of multiple coronary artery--left ventricular communications (prominent Thebesian system) are presented. The literature has been reviewed and the clinical, electrocardiographic, scintigraphic and angiographic findings of 28 collected cases are discussed.
A case is reported of recurrent intracerebral abscesses occurring in a patient with isolated drainage of a persistent left superior vena cava to the left atrium without causing cardiac symptoms or arterial desaturation. The diagnosis and therapy are discussed.
The incidence of recurrent ischemia, congestive heart failure and death during the first year after discharge were analysed prospectively in a group of 312 patients randomized double blindly to rt-PA (n = 156) or placebo within 5 hours after the onset of acute myocardial infarction. The in-hospital mortality was 4.4% in the rt-PA and 6.4% in the placebo group; the total-mortality after a follow-up of 16 months was respectively 7.6 and 9.6%. During 16 months follow-up reinfarction occurred in 5.4% of the rt-PA treated patients versus 0.0% in controls (p = 0.004). Revascularization was required in 17% of the population (24% in rt-PA versus 16% in controls, N.S.), angina at rest and congestive heart failure, demanding hospitalization developed in 5.1% of the patients (5.3% in rt-PA versus 4.7% in controls, N.S.) and 3.4% of the patients in each group died after discharge. A logistic model constructed to predict event-free survival showed that enzymatic infarct size, exercise capacity and the hemodynamic response at a predischarge bicycle exercise test and end-systolic volume at 2 weeks were predictors of new events. Considerable overlapping between patients with and without a new event was observed.
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An increasing body of evidence suggests that the potential for thrombotic complications is greater with nonionic than with ionic contrast agents. This is a particularly important consideration in the highly thrombogenic setting of percutaneous transluminal coronary angioplasty (PTCA). To explore this issue further, 500 consecutive patients undergoing PTCA were prospectively randomized to receive the low osmolality ionic ioxaglate or the nonionic agent iohexol. The number of acute thrombotic in-laboratory events was significantly less in the ioxaglate than in the iohexol group (8 versus 18; P < 0.05), but there was no significant difference between the 2 groups as regards the number of out-of-laboratory acute rethrombotic events. With multivariate analysis, use of the nonionic agent rather than the ionic agent emerged as an independent predictor of acute in-laboratory rethrombosis. These data suggest that, in the performance of PTCA, an ionic, rather than a nonionic, should be the preferred contrast agent.
We reviewed the coronary angiographic findings of 19 patients with a cardiac myxoma, who underwent cardiac catheterization before surgery. Seventeen myxomas were localized in the left atrium and seven had angiographically visible tumor vascularity emerging from atrial branches of the right coronary artery in four patients and the circumflex coronary artery in three. In one patient, we found significant coronary artery disease of the circumflex coronary artery and in another we saw a thrombus-like lesion in the proximal third of the left anterior descending coronary artery. Our results are compared with the findings in two smaller groups of patients with cardiac myxoma who underwent coronary angiography preoperatively. We conclude that the major importance of coronary angiography in patients with cardiac myxomas is to exclude concomitant coronary artery disease before surgery. In a very small minority of patients, a selective coronary angiography is the clue to the diagnosis of cardiac myxoma.
In this study a new method for assessment of perfusion defects (PDs) derived from myocardial perfusion tomograms was evaluated in patients treated with thrombolytic therapy. Using global constraints and dynamic programming, a model-based delineation algorithm defined myocardial borders, the basal plane and absolute and relative PD size in 49 thallium-201 chloride (201TL CL) and 60 technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) tomograms. Tomographic (single-photon emission tomography: SPET) and planar quantification of PDs was compared to enzymatic infarct size as well as to global (LVEF) and regional ventricular function (RWM) obtained by contrast angiography. The algorithm delineated the myocardium and the valve plane in most cases, even when large PDs were present. Manual correction of the automatic delineation of the basal plane was necessary in less than 20% of the studies. Using 201Tl Cl, LVEF correlated better with tomographic PD (r = -0.67) than with planar PD (r = -0.54). Comparing planar to tomographic imaging using 99mTc-MIBI, a higher correlation with enzymatic infarct size (r = 0.73 vs 0.57) and with global ventricular function (r = 0.64 vs -0.52) was found when tomographic techniques were used. No close correlation between PD and RWM was found. The beneficial effect of thrombolysis was shown by a significant difference of PD in patients with open versus occluded infarct-related vessels. It can be concluded that this new automated algorithm for quantification of SPET perfusion defect size provides a useful tool in evaluating thrombolytic therapy.
Using global constraints and dynamic programming, a new model-based segmentation algorithm was developed to determine myocardial borders and basal plane. The segmented image is transformed to a countrate polar map and the infarct size (I.S.) is determined by comparison with a reference polar map. In order to evaluate our method the algorithm was applied to heart phantoms, to software simulations and to animal studies. In the last experiments, Tc-99m Sestamibi was used as a perfusion agent. The total myocardial volume and infarct size of a Jasczack phantom were overestimated, especially when I.S. was expressed in absolute rather than relative values. It was proven by software simulations of cardiac Spect studies that those errors were mainly due to finite resolution effects causing a clear overestimation of myocardial thickness. Implementation of a constant thickness in the algorithm resulted in a much better correlation with actual values. In a dog experiment the size of total myocardial volume of the area at risk during occlusion and of the final infarct size after thrombolysis was correlated with the histologic values obtained by planimetry after TTC staining. In 8 studies, an excellent correlation between the histologic area at risk versus the estimated perfusion defects was obtained (r = 0.97). The automatic delineation of myocardial borders and valve plane was excellent even when perfusion defects were present. Manual intervention was only necessary in certain slices where a clear overlap between liver and myocardium was present in the dog studies. Segmental polar maps expressing count rate and volume information provided a visual and quantitative tool to evaluate the influence of thrombolysis in acute ligation experiments. It is concluded that the new algorithm is ready to be used in a clinical environment for the quantitative evaluation of perfusion defects after acute myocardial infarction and for the follow-up of the therapeutic strategy.
OBJECTIVES: The aim was to investigate (1) whether collateral bronchopulmonary circulation developing due to chronic pulmonary embolism could prevent the evolution of pulmonary infarction after induction of pulmonary venous outflow impairment; and (2) how collateral bronchopulmonary circulation developed after acute embolisation of the lung with impaired pulmonary venous outflow. METHODS: Fifty two mongrel dogs were studied. Thirty six dogs were experimental animals and 16 were in a control group. Unilateral impairment of pulmonary venous outflow was induced by constriction of the left pulmonary veins in two groups of experimental dogs: (1) three months after and (2) one hour before bilateral embolisation of the pulmonary artery. All animals were killed 12 days after constriction. The size of the bronchial arteries was evaluated from angiograms. The diameter and the wall thickness of the arteries were measured during histology. RESULTS: In all experimental dogs, haemorrhagic infarctions developed distally to emboli in the left lung regardless of whether the bronchial arteries were dilated before induction of pulmonary venous constriction or whether collateral circulation started to develop after pulmonary venous constriction. Constriction of the pulmonary veins was an essential factor for pulmonary infarction to develop as no infarction developed in the embolised regions of the right lungs with intact pulmonary venous outflow. Pulmonary venous constriction alone did not cause dilatation or hypertrophy of the bronchial arteries. After pulmonary artery embolisation, the same enlargement and hypertrophy of the bronchial arteries occurred both in the left lung with previously impaired venous outflow and in the right lung with intact pulmonary veins. CONCLUSIONS: Expanded bronchopulmonary circulation did not prevent the development of infarction in the embolised region of the lung with impaired pulmonary venous outflow. Development of collateral bronchopulmonary circulation was not influenced by previously impaired pulmonary venous outflow.
In the evaluation of antiarrhythmic treatment, total mortality and total cardiac mortality are the only endpoints difficult to misclassify. End-stage cardiac failure competes with "suddenness" in many instances of sudden arrhythmic death. This observational study reports on 23 deaths in a group of 129 patients under antiarrhythmic treatment. In the 21 cases of cardiac death, with respect to the notion "sudden arrhythmic death," classification was problematic in 6 patients. According to different interpretations, the number of deaths listed as "sudden" could vary between one and six. A concise description of cause and circumstances of death, is presented.
The usefulness of echocardiography and Doppler for the detection of acute myocardial ischemia was evaluated during right coronary artery occlusion in 20 patients. The echocardiographic findings were compared with the occurrence of chest pain, and to electrocardiographic and hemodynamic changes obtained during percutaneous transluminal coronary angioplasty. Our results confirm that, even in the case of small segmental myocardial ischemia, two-dimensional echocardiography is superior to all other measured parameters. In contrast, Doppler examination of transmitral flow is not sensitive enough for the detection of such small segmental myocardial ischemia induced by right coronary artery occlusion.
The differentiation between constrictive pericarditis and restrictive cardiomyopathy remains a difficult problem for clinical cardiologists. Recent advances in imaging techniques and the understanding of diastolic function have created a new diagnostic approach to this problem. In this article we will summarize the recent advances in the understanding of the pathophysiology of both disorders and how this is reflected mainly in the use of flow imaging techniques, such as Doppler echocardiography and radionuclide angiography. Combined with the advances in the radiological imaging of the pericardium by means of computed tomography and magnetic resonance imaging, an integrated approach to the differential diagnostic problem is proposed and an algorithm for clinical use has been designed.
Two patients with large pericardial thrombi following cardiac surgery presented as having right cardiac tamponade. Transesophageal echocardiography (TEE) identified a large pericardial hematoma compressing the right atrium and was well tolerated by these critically ill patients. These case reports demonstrate the diagnostic value of TEE in the identification of this severe complication in the late postoperative period.
Two cases of orthostatic dyspnea and arterial desoxygenation, as a postpneumonectomy complication, are reported. In one patient, echocardiography and cardiac catheterization revealed the presence of an atrial septal aneurysm, which has never been described in association with the platypnea-orthodeoxia syndrome. The other case illustrates that, despite actual technical possibilities, clinical suspicion remains a prerequisite for proper diagnosis of the entity.
The aim of the study was the functional re-evaluation of 296 patients 12 to 18 months after a double-blind trial evaluating the effect of tissue plasminogen activator (rt-PA) versus placebo given within 5 h of onset of symptoms caused by an acute myocardial infarction. All patients underwent rest-stress radionuclide angiography (Egna). For each exercise level the global left ventricular ejection fraction (LVEF) was calculated together with an estimate of regional wall motion abnormalities (RWMA). A clear difference of the total workload and the peak workload was found between both therapeutic groups. Discriminant analysis evaluating four parameters (LVEF at peak exercise and at the endpoint and the workload at those levels) revealed a beneficial therapeutic effect. The RWM at rest showed only a difference in the apico-inferior region. There were less wall motion abnormalities in the treated group. Radionuclide analysis demonstrated a larger functional capacity and a better coordination of myocardial contractility during stress RNA one year after thrombolytic therapy. At rest, no major differences were found between the hospital stage and the follow-up in both therapeutic groups one year later.
The ability of echocardiography to visualize ventricular wall motion abnormalities induced by ischaemia and infarction makes it an ideal tool in the assessment of patients with acute myocardial infarction. Echocardiographic derived measurements of infarction severity, such as the wall motion score index, correlate well with both early and late complications. Echocardiography is of considerable value in the detection of mechanical complications of myocardial infarction such as aneurysm and thrombus formation, infarction expansion, ventricular septal rupture and mitral regurgitation; Doppler echocardiography is of particular worth in the detection of the latter two complications. Serial echocardiographic imaging before and after various coronary reperfusion strategies allows useful assessment of the success of these strategies. Following a myocardial infarction, a predischarge resting or exercise 2-dimensional echocardiographic study provides valuable information regarding the likelihood of adverse cardiac events during long term follow-up.
UNLABELLED: The value of intracoronary ultrasound for quantitative assessment of minimal coronary arterial diameter and for on-line evaluation of balloon angioplasty result was studied in 42 patients undergoing single vessel coronary angioplasty. Measurement of minimal luminal diameter of 75 matched coronary arterial segments showed a significant correlation between both the ultrasound and angiographic method (r: 0.759; p < 0.001). Furthermore using intravascular ultrasound it was possible to classify the obtained coronary balloon angioplasty results. A preliminary correlation between ultrasound classification and the in-hospital acute rethrombosis as well as late restenosis was attempted in individual patients. CONCLUSIONS: 1) Clinical use of coronary ultrasound is feasible and safe in selected cases. 2) A significant correlation between intracoronary ultrasound and quantitative coronary angiography is demonstrated. 3) Using intracoronary ultrasound seems promising for evaluation of the postangioplasty result, and may finally lead to improved selection of the interventional strategy.
Ninety-three patients, who underwent DC shock ablation were reviewed over a mean follow-up period of 54 months (range 3 to 84 months). These patients (46 male and 47 female, mean age: 58 years) had failed an average of 3 drugs, and the duration of symptoms was more than 2 years. Paroxysmal atrial fibrillation or flutter was treated in 75 patients (80.6%); the remainder had supraventricular tachycardia or reciprocating tachycardia using an accessory pathway. One shock of 200 J was effective in producing third degree AV block in 40 patients (43%), while 2 or more shocks were used in another 53 patients (57%). Chronic complete heart block (CHB) was obtained in 85 patients (91%), modification of conduction was seen in 2 patients (2.1%), and failure to achieve an improvement in 6 patients (6.4). All the patients of the last group had received more than 4 shocks (200 to 400 J). However no significant difference between the amplitude of atrial and His electrograms could be shown between the CHB patients and those in whom conduction persisted. Over a mean follow-up of 54 months, 66 patients (72%) with successful ablation during the first 48 hours after the procedure remained in CHB. In 18 patients AV conduction resumed but they were all asymptomatic: 10 patients (10.8%) without antiarrhythmic therapy and 8 patients (8.6%) with medication. In conclusion, ablation of the AV junction is effective in more than 82% of patients. Most of the time long-term success can be predicted within 48 hours. However, due to the invasive character of DC shocks, this technique has been supplanted by the less aggressive radiofrequency method.