George Louridas

Airway Function in Stage I and Stage II Pulmonary Sarcoidosis

Airway function was studied in 39 patients with stage I sarcoidosis and in 20 patients with stage II sarcoidosis. All of our patients were nonsmokers. Characteristic functional changes of restrictive lung disease was observed in 4 patients with stage II sarcoidosis. Specific airway conductance and % FEV1 were abnormal in 3 patients with stage II sarcoidosis. Abnormal small airway function was demonstrated in several patients with stage I and stage II sarcoidosis, always by multiple tests. Frequency dependence of dynamic compliance was demonstrated in 40% of stage I and 50% of stage II sarcoidosis. Maximal flow (Vmax50, Vmax25) was decreased respectively in 36 and 30% of patients of stage I sarcoidosis and in 56 and 62% of patients with stage II sarcoidosis. The ratio of closing volume to vital capacity was increased above corrected predictions in 30% of stage I and 44% of stage II sarcoidosis. delta Vmax25 decreased and Visov/VC (%) increased in more than 50% of patients. Upstream airway resistance was abnormally increased in 50% of patients with stage I and in 73% with stage II sarcoidosis. These results suggest that small airway dysfunction is common in early sarcoidosis without restrictive defect.

Interactions among the critical factors affecting sinus node function: The quantitative effects of the duration and frequency of atrial pacing and of vagal and sympathetic stimulation upon overdrive suppression of the sinus node

A multifactorial analysis was used in anesthetized dogs in order to characterize the effects of the duration of overdrive, the atrial pacing interval, and the frequencies of vagal and sympathetic stimulation on overdrive suppression of the sinus node. The sinus node recovery time (SNRT) and the summated effect (SE) over the first 20 cardiac cycles were measured with various combinations of the independent variables. We conclude that (1) both the rate and the duration of overdrive have significant effects on SNRT and SE; (2) vagal stimulation has greater effects on SNRT and SE than does the rate or duration of overdrive; (3) sympathetic stimulation had only a small effect on overdrive suppression; and (4) there were significant interactions between vagal stimulation and the duration of overdrive and between the duration and rate of overdrive, but not between sympathetic and vagal stimulation.

Left Ventricular Function in Patients with Chronic Obstructive Pulmonary Disease

We assessed the left ventricle function in 24 patients with severe (forced expiratory volume in 1 sec less than 50% of predicted) chronic obstructive pulmonary disease (COPD) and in 21 normal people. We measured the left ventricular systolic time intervals (STI) and echocardiographic left ventricular diameters, volumes, cardiac index, stroke volume index, echo ejection fraction and functional mean rate of circumferential fiber shortening (Vcf). In 13 of the 24 patients with COPD the mean pulmonary artery pressure and pulmonary artery wedge pressure were recorded. The STI in the patients with COPD were found abnormal while the echocardiographic parameters and pulmonary wedge pressure were normal. 1 patient had a high pulmonary arterial wedge pressure and a low Vcf. 2 patients had an ejection fraction less than 60%, but in only 1 of these the Vcf was low. No patient had all three parameters abnormal. We conclude that in patients with COPD the increased right ventricular afterload and the interaction between left and right ventricles are responsible for the abnormal left ventricular STI, while the left ventricular function is normal.

Pulmonary Hypertension and Respiratory Failure in the Development of Right Ventricular Hypertrophy in Patients with Chronic Obstructive Airway Disease

The high incidence of right ventricular hypertrophy in patients with chronic obstructive pulmonary disease is a well-known fact. In clinical medicine according to our present status of thinking, severe impairment of ventilatory function and pulmonary hypertension are the two essential prerequisites for right ventricular involvement. To investigate this accepted assumption we studied 51 patients with chronic obstructive pulmonary disease, while they were in a remission period. The patients were subjected to clinical examination, chest roentgenography, spirometry, blood gas examination, electrocardiography, vectorcardiography, echocardiography, and right heart catheterization. The majority of the patients with significantly compromised ventilatory function and abnormal blood gases had right ventricular hypertrophy with elevation of the pulmonary artery pressure. Two subgroups of patients could be distinguished: One included 15 patients (29.4% of all patients) with normal pulmonary artery pressure and evidence of right ventricular hypertrophy. In this subgroup are included 10 patients (19.6% of all patients) showing mild ventilatory impairment and mild hypoxaemia. The second subgroup consisted of 5 patients (9.8% of all patients) with elevated mean pulmonary artery pressure at rest and right ventricular hypertrophy showing relatively mild ventilatory impairment and moderate hypoxaemia. Two conclusions could be drawn: (1) the pulmonary artery pressure at rest could be normal despite the evidence of right ventricular hypertrophy, and (2) a mild ventilatory impairment does not exclude an elevated pulmonary artery pressure or the development of right ventricular hypertrophy in patients with chronic obstructive pulmonary disease.

Control of breathing in patients with chronic obstructive lung diseases and secondary polycythemia after venesection

Using the mouth occlusion pressure technique, we have studied the control of breathing in 10 hypercapnic patients with chronic obstructive pulmonary diseases and polycythemia before and after venesection. The mean hematocrit value was 59.9 +/- 5.5% which, following venesection (approximately 1,200-1,600 cm3 of blood was removed from each patient over three consecutive days), fell to 44.4 +/- 2.2%. Respiratory drive, expressed as P0.1 (mouth occlusion pressure 0.1 s after the onset of occluded inspiration at functional residual capacity) and as mean inspired flow (VT/TI), was diminished after venesection (p less than 0.001 and p less than 0.05); in contrast to that, we found no changes in respiratory timing (TI and TI/Ttot). The arterial PCO2 was decreased (p less than 0.001) and arterial PO2 was increased after venesection, these improvements are mainly attributed to decreased dead space ventilation (p less than 0.05). It seems that the improvements of blood gases after venesection is probably responsible for the decrease in respiratory drive.

Concomitant presence of left anterior hemiblock and inferior myocardial infarction: Electrocardiographic recognition of each entity

The ECGs of 72 patients with an unequivocal vectorcardiographic diagnosis of either left anterior hemiblock (LAH) or inferior myocardial infarction (IMI) or both were reviewed. Our intention was to identify definite electrocardiographic criteria for the diagnosis of the left anterior hemiblock and of inferior myocardial infarction when both were present vectorcardiographically. All patients with left anterior hemiblock, accompanied or not by IMI, had a left axis deviation, a negative terminal deflection (S wave) in leads II, III and a VF; the majority of them also had a terminal r wave in lead a VR (50 of 52, 96%). The diagnosis of LAH was therefore always possible in the concomitant presence of both entities. A negative initial deflection (Q wave) significant in size or not significant was present in a minority of patients with both LAH and IMI (9 of 24, 37.5% in lead II; 7 of 24, 25% in lead III; and 12 of 24, 50% in lead aVF). In the patients with insignificant Q waves, as well as in the rest of the patients with rS configuration, the electrocardiographic diagnosis of IMI was not possible due to the concomitant presence of LAH.

Respiratory Drive in Patients with Chronic Obstructive Pulmonary Disease

Respiratory drive (deltaP 0.1/deltaPCO2) and ventilatory response (deltaVE/deltaPCO2) to CO2 has been estimated in 20 normal subjects and 28 patients with chronic obstructive pulmonary disease (COPD). In patients with COPD, drive and ventilatory response to CO2 were diminished, but no statistical correlation with FEV1, MBC, TLC, FRC, RV/TLC was found. A statistically negative correlation was found between blood bicarbonate and drive or ventilatory response to CO2. Patients with emphysema and normal PaCO2 demonstrated normal deltaP 0.1/deltaPCO2. In contrast, patients with chronic bronchitis with the same pulmonary function abnormalities and hypercapnia had significant diminution of the deltaP 0.1/deltaPCO2. Therefore, we feel that pulmonary function abnormalities alone cannot explain the deltaP 0.1/deltaPCO2 decrease; in most cases there sould coexist a diminished respiratory sensitivity.

Direct and incomplete concealed Wenckebach phenomena in the left bundle-branch system

A case is reported showing a tachycardia dependent Wenckebach phenomenon in both the A-V node and the left bundle branch system. Pacing from the His bundle region induced manifest (direct) and imcompletely concealed (indirect) types of Wenckebach phenomenon within the left bundle branch system.

Systolic Time Intervals in Chronic Obstructive Pulmonary Disease

The systolic time intervals (STI) were used to study the left ventricular performance in 51 patients with chronic obstructive pulmonary disease (COPD), in 24 normal subjects and in 13 patients with both COPD and coronary heart disease (CHD). Our study shows that resting spine STI are abnormal in patients with COPD and that the STI in the sitting position and after exercise in these patients are changing in a similar way to those of normal subjects. In patients with both COPD and CHD we found the resting supine STI and the postexercise left ventricular ejection time index (LVETI) to differ from both normals and patients with COPD alone. When these same patients were sitting the STI failed to change, in striking contrast to the normal subjects and to the patients with COPD alone. The similar responses of normal subjects and of patients with COPD in the two stress conditions as well as the different postural and postexercise responses of patients with both COPD and CHD suggest a normal left ventricular function in patients with COPD.

Coronary Involvement After a Single Myocardial Infarction

Coronary angiography was performed in 95 patients 3 months to 3 years after a single myocardial infarction. The patients were categorized into 4 groups according to coronary angiography findings: grou