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Blood stasis is the main cause of left atrial thrombosis (LAT) in atrial tachyarrhythmias. The high-velocity flow inside the left atrium, due to mitral valve regurgitation, may prevent clot formation but the topic has never been investigated in large-scale studies. The aim of our study was to evaluate whether the presence and degree of mitral regurgitation have a protective role against LAT risk.A total of 1302 consecutive adult patients with paroxysmal or persistent atrial fibrillation or flutter undergoing cardioversion, submitted to transesophageal echocardiography, were retrospectively enrolled in the study. The study population was divided into three groups according to the mitral regurgitation degree: absent, mild-to-moderate and severe.Among 1302 patients enrolled in the study, patients without mitral regurgitation were 248 (19%), those with mild-to-moderate 970 (75%), whereas 84 had severe mitral regurgitation (6%). LAT incidence was significantly lower in patients with severe mitral regurgitation compared with those with mild-to-moderate (mitral regurgitation) (2.4 vs. 8.9%, P 0.05), and similar to subjects without mitral regurgitation (2.4%).Despite patients with severe regurgitation having clinical and echo characteristics predisposing to LAT (higher age, heart failure, higher atrial size, lower ventricular function) thrombosis prevalence was significantly lower than for those with mild-to-moderate mitral regurgitation. The percentage of LAT in severe mitral regurgitation cases was very low and similar to that of cases without regurgitation which were characterized by lower age, normal left ventricular function or other risk factors, reinforcing the hypothesis of a protecting role against atrial thrombosis of mitral regurgitation.

Aims The aim of this study, undertaken in patients who underwent mitral valve (MV) repair surgery, was to evaluate the accuracy of pre-operative three-dimensional (3D) transthoracic echocardiography (TTE) in the evaluation of MV pathology in cases with simple or complex lesions. Methods and results Two hundred consecutive patients with severe mitral regurgitation due to degenerative MV prolapse underwent a complete 3DTTE the day before surgery. Three-dimensional TTE data were compared with MV surgical inspection. Three-dimensional echocardiography was feasible in a relatively short time (5 ± 3 min) with good (67%) and optimal (21%) imaging quality in the majority of cases. Three-dimensional TTE allowed an accurate identification (95% accuracy) of all MV lesions. Seventy-three (36.5%) patients had simple lesions at 3DTTE and 71 of them (97.2%) underwent a simple surgical procedure; 127 (63.5%) had complex lesions at 3DTTE and, in these cases, surgeons performed either simple procedures (48%) or complex procedures (47.2%) or valve replacement in 4.7% (after a first attempt for repair). Conclusion Three-dimensional TTE is feasible, not time-consuming, and accurate in identifying cases with simple vs. complex MV lesions.

A new generation of transoesophageal echocardiographic probes with a novel matrix array technique has been recently introduced, allowing three-dimensional (3D) presentation of cardiac structures in real-time. This new tool may potentially provide fast and complete 3D information about cardiac structures improving spatial orientation and overcoming limitations of offline 3D technologies. The aim of this study was to demonstrate the feasibility and usefulness of real-time 3D transoesophageal echocardiography (TOE) for the intraoperative evaluation of cardiac surgery procedures. One-hundred patients underwent transoesophageal echocardiographic examination during cardiac surgery as a part of their routine clinical practice. In the intraoperative pre- and post-cardiopulmonary bypass periods complete 2D and 3D transoesophageal examinations were performed. Feasibility and duration of examinations, and immediate additional anatomical value of 3D versus 2D-TOE were annotated intraoperatively. Image quality, additional clinical value of 3D- compared to standard 2D-TOE and the accuracy in the description of mitral valve pathology by a surgeon and an echocardiographer were evaluated off-line. No complications related to transoesophageal examination occurred and successful intubation was achieved in all 100 patients. Therefore, 200 examinations were performed and analysed considering the pre- and post-cardiopulmonary bypass periods. The mean number of acquisitions per patient was 16 +/- 14, including 3D real-time, zoom, full-volume and colour full volume modalities. The duration of the 3D examination was 16 +/- 10 min and the mean image quality score 2.8 +/- 0.7 (in a scale 1-4). In 36 out of 100 cases (36%) 3D-TOE provided additional anatomical information. The surgeon evaluated 3D images easier and more accurately than 2D images (88% vs. 76% in the evaluation of mitral valve scallop). Real-time 3D TOE may be used routinely for the intraoperative evaluation of cardiac surgery. Imaging with this new probe facilitates intraoperative evaluation of several surgical procedures with an additional clinical value in selected cases.

Objectives Transesophageal echocardiography (TEE)-guided cardioversion has been demonstrated to be well tolerated in patients with atrial fibrillation. Guidelines do not suggest whether patients with severe spontaneous echocontrast (SEC) and sludge can be safely submitted to cardioversion. In our observational study, we analyzed the prevalence of SEC in patients with atrial fibrillation taking different anticoagulant therapies, the incidence of embolic complications after cardioversion in patients with severe SEC or sludge and the usefulness of TEE in reducing embolic complications in these patients. Methods The study population consisted of 1104 patients with atrial fibrillation, candidates for cardioversion and submitted to TEE. They were divided into four groups: effective conventional oral anticoagulation, short-term anticoagulation, subtherapeutic anticoagulation and effective oral anticoagulation for less than 3 weeks for different clinical reasons. Cardioversion was postponed in patients with atrial thrombosis; in the presence of severe SEC, the decision to cardiovert was left to the treating physician. Results Atrial thrombosis was detected in 65 (5.9%) patients, and SEC was detected in the majority of patients independent of the anticoagulant scheme; in 131 patients, it was severe and, in this group, sludge was identified in 57 patients. Cardioversion was performed in 922 patients and was successful in 849 (including 22 patients with severe SEC and four with sludge) with one minor embolic event. Conclusion SEC and sludge are frequently observed in patients with atrial fibrillation undergoing cardioversion. A TEE approach may prevent the risk of embolic events. In the presence of severe SEC and sludge, treating physicians frequently postpone cardioversion, even though in the patients submitted to cardioversion, no events were observed.

The radiofrequency maze procedure achieves sinus rhythm in 45%–95% of patients treated for atrial fibrillation. This retrospective study evaluates mid-term results of the radiofrequency maze—performed concomitant to elective cardiac surgery—to determine sinus-rhythm predictive factors, and describes the evolution of patients' echocardiographic variables. From 2003 through 2011, 247 patients (mean age, 64 ± 9.5 yr) with structural heart disease (79.3% mitral disease) and atrial fibrillation underwent a concomitant radiofrequency modified maze procedure. Patients were monitored by 24-hour Holter at 3, 6, 12, and 24 months, then annually. Eighty-four mitral-valve patients underwent regular echocardiographic follow-up. Univariate and multivariate analysis for risk factors of maze failure were identified. The in-hospital mortality rate was 1.2%. During a median follow-up of 39.4 months, the late mortality rate was 3.6%, and pacemaker insertion was necessary in 26 patients (9.4%). Sinus rhythm was present in 63% of patients at the latest follow-up. Predictive factors for atrial fibrillation recurrence were arrhythmia duration (hazard ratio [HR]=1.296, P=0.045) and atrial fibrillation at hospital discharge (HR=2.03, P=0.019). The monopolar device favored maze success (HR=0.191, P Concomitant radiofrequency maze procedure provided remarkable outcomes. Shorter preoperative atrial fibrillation duration, monopolar device use, and prompt treatment of arrhythmia recurrences increase the midterm success rate. Early sinus rhythm restoration seems to result in better left ventricular ejection fraction recovery.

Background. Maze procedure aims at restoring sinus rhythm (SR) and atrial contractility (AC). This study evaluated multiple aspects of AC recovery and their relationship with SR regain after ablation.Methods. 122 mitral and fibrillating patients underwent radiofrequency Maze. Rhythm check and echocardiographic control of biatrial contractility were performed at 3, 6, 12, and 24 months postoperatively. A multivariate Cox analysis of risk factors for absence of AC recuperation was applied.Results. At 2-years follow-up, SR was achieved in 79% of patients. SR-AC coexistence increased from 76% until 98%, while biatrial contraction detection augmented from 84 to 98% at late stage. Shorter preoperative arrhythmia duration was the only common predictor of SR-AC restoring, while pulmonary artery pressure (PAP) negatively influenced AC recuperation. Early AC restoration favored future freedom from arrhythmia recurrence. Minor LA dimensions correlated with improved future A/E value and vice versa. Right atrial (RA) contractility restoring favored better left ventricular (LV) performance and volumes.Conclusions. SR and left AC are two interrelated Maze objectives. Factors associated with arrhythmia “chronic state” (PAP and arrhythmia duration) are negative predictors of procedural success. Our results suggest an association between postoperative LA dimensions and “kick” restoring and an influence of RA contraction onto LV function.

Aim Transient coronary artery occlusion during percutaneous transluminal coronary angioplasty may cause left ventricular diastolic dysfunction. The aim of this study was to evaluate the effect of left anterior descending, left circumflex and right coronary artery balloon occlusion on right ventricular diastolic function. Methods Thirty-five patients with single-vessel coronary artery disease and no previous myocardial infarction were selected. Left and right ventricular filling pressures were monitored by Doppler echocardiography and haemodynamic monitoring. This was performed during and immediately after 60 s of coronary balloon occlusion of the left anterior descending artery in 21 cases (Group 1), the left circumflex artery in eight cases (Group 2) and the right coronary artery in six cases (Group 3). Doppler analysis of left and right ventricular filling included peak velocity of early (PFVE) and late ventricular filling (PFVA) and PFVE to PFVA ratio (PFVE/PFVA). Results In all three groups, balloon inflation induced a significant increase in left and right filling pressures ( P

The Doppler formulas currently used for right ventricular systolic pressure (RVSP) evaluation include right ventricular-right atrial (RV-RA) gradient and RA pressure. The former is expressed by the velocity of the trans-tricuspid regurgitant flow; the latter is generally assumed and is different from one formula to another. In 110 patients with cardiac disease with normal or elevated pulmonary pressure, we tested a new echo-Doppler formula for the evaluation of RVSP based on the estimation of RA pressure by means of the inferior vena cava collapsibility index (IVCCI) and compared this method with two traditional formulas (methods A and B) and with cardiac catheterization values. Patients were classified into three groups on the basis of IVCCI (group 145%, group 2 between 35% and 45%, and group 335%). RVSP was evaluated by method A (RV-RA gradient + 10), method B (RV-RA gradient x 1.1 + 14), and our new method, method C, which assigns 6, 9, and 16 mmHg to RA pressure in the presence of normal (45%), moderately reduced (between 35% and 45%), or markedly reduced (35%) IVCCI, respectively. IVCCI correctly identified RA pressure in the three groups (group 1, 6.8 mmHg; group 2, 10.8 mm Hg; and group 3, 13.1 mmHg); a high correlation existed between Doppler-derived and invasively determined RV-RA gradient (r = 0.99). Method C improved noninvasive estimation of RVSP in groups 1 and 3 compared with the other methods; in group 2, Doppler estimation of RVSP by methods A and C were comparable, whereas method B significantly overestimated the actual values.(ABSTRACT TRUNCATED AT 250 WORDS)

Right ventricular (RV) dimensions and function are of diagnostic and prognostic importance in cardiac disease. Because of the peculiar morphology of the right ventricle, 2-dimensional echocardiography has several limitations in RV evaluation. Recently, new 3-dimensional transthoracic echocardiographic software adapted for RV morphology was introduced. The aims of this study were to evaluate the feasibility of 3-dimensional RV analysis in a large population and to compare and correlate 3-dimensional RV data with classic 2-dimensional and Doppler parameters, including tricuspid annular plane systolic excursion and peak systolic velocity on Doppler tissue imaging, RV fractional shortening area, RV stroke volume (by the Doppler method), and pulmonary arterial systolic pressure. Two hundred subjects were studied: 48 normal controls and 152 patients with valvular heart disease (104 patients), idiopathic dilated cardiomyopathy (20 patients), or pulmonary hypertension (28 patients). The mean times for 3-dimensional acquisition and 3-dimensional reconstruction were 3 +/- 1 and 4 +/- 2 minutes, respectively. Imaging quality was good in most cases (85%). The mean RV diastolic and systolic volumes were 103 +/- 38 and 46 +/- 28 ml, respectively. The RV ejection fraction (RVEF) was correlated negatively with pulmonary arterial systolic pressure and positively with tricuspid annular plane systolic excursion, peak systolic velocity, and fractional shortening area. The pathologic group was characterized by larger RV volumes and lower RVEFs. Three-dimensional echocardiography clearly showed that in the pathologic group, patients with pulmonary hypertension had the largest RV volumes and the lowest RVEFs and that those with idiopathic dilated cardiomyopathy were characterized by RVEFs lower than those of patients with valvular disease. In conclusion, this new quantitative 3-dimensional method to assess RV volumes and function is feasible, relatively simple, and not time consuming. Data obtained with 3-dimensional analysis are well correlated with those obtained by 2-dimensional and Doppler methods and can differentiate normal and pathologic subjects.

We investigated the acute effects of nifedipine (10 mg orally) on renin and systemic hemodynamics in twelve patients who had severe hypertension (diastolic values averaging 114 mm Hg) with unilateral renal artery stenosis (angiography) and hyperreninemia. Plasma renin activity was determined from blood samples drawn from the aorta and from both renal veins, so that "ischemic lateralization" could be evaluated through appropriately derived indexes. Nifedipine promptly and significantly lowered aortic pressure in all patients. At 30 minutes maximal circulatory responses were recorded, which consisted of a 22% decrease in mean aortic pressure (from an average of 144.6 +/- 15 mm Hg to an average of 113 +/- 11 mm Hg), a 44% reduction of systemic vascular resistance (from 2162 +/- 540 dynes.sec.cm-5 to to 1205 +/- 279 dynes.sec.cm-5), a 33% rise in cardiac index (from 2920 +/- 970 ml/min/m2 to 3875 +/- 986 ml/min/m2). These effects were still evident, although somewhat tempered, after 180 minutes of continuous monitoring; they were qualitatively and quantitatively similar to those reported by some authors in persons with primary hypertension with similar levels of blood pressure. After nifedipine was given, renin activity of the systemic blood rose significantly, because of a potentiated release from the kidney with arterial stenosis. This effect, which was inferred as being due to further reduction of the renal perfusion pressure, improved the significance of "ischemic lateralization" indexes and supported the diagnosis of renovascular hypertension in all cases.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic valve diseases, hypertension, and connective tissue disorders may be causes of ascending aortic aneurysms. Aortic enlargement monitoring is essential for surgical timing and for operative design. In this regard, several imaging techniques may have limitations: magnetic resonance is not widespread and is expensive, computed tomography uses radiation, and transesophageal echocardiography is a semi-invasive method. The aim of this study was to analyze the feasibility of transthoracic echocardiography in the evaluation of aortic dimensions and its accuracy in comparison with multidetector computed tomography. In 44 patients with known ascending aortic aneurysms, transthoracic echocardiographic and computed tomographic measurements were obtained and compared at different levels: the annulus, sinuses of Valsalva, sinotubular junction, ascending aorta, and aortic arch. Transthoracic echocardiographic diameters were obtained in all patients, apart from the aortic arch, which was measured in 40 cases. Transthoracic echocardiographic and computed tomographic diameters correlated significantly (p

Objectives The aim of this study, undertaken in patients who underwent mitral valve (MV) repair surgery, was to evaluate the feasibility and accuracy of 3-dimensional (3D) transthoracic (TTE) and transesophageal (TEE) echocardiography in the evaluation of MV pathology. Background A pre-operative assessment of MV anatomy is essential to surgical design in patients undergoing MV repair. Although 2-dimensional (2D) echocardiography provides precise information regarding MV anatomy, 3D TTE and 3D TEE could increase the understanding of MV apparatus and individual scallop identification. Methods One-hundred-twelve consecutive patients with severe mitral regurgitation due to MV prolapse underwent a complete 2D and 3D TTE the day before surgery and a complete 2D and 3D TEE in the operating room. Echocardiographic data obtained by the different techniques were compared with surgical inspection. Results Three-dimensional techniques were feasible in a relatively short time (3D TTE: 7 +/- 4 min; 3D TEE: 8 +/- 3 min), with good (3D TTE 55%; 3D TEE 35%) and optimal (3D TTE 21%; 3D TEE 45%) imaging quality in the majority of cases. Three-dimensional TEE allowed more accurate identification (95.6% accuracy) of all MV lesions in comparison with other techniques. Three-dimensional TTE and 2D TEE had similar accuracies (90% and 87%, respectively), whereas the accuracy of 2D TTE (77%) was significantly lower. Conclusions Three-dimensional TTE and TEE are feasible and useful methods in identifying the location of MV prolapse. They were superior in the description of pathology in comparison with the corresponding 2D techniques and should be regarded as an important adjunct to standard 2D examinations in decisions regarding MV repair.

Transesophageal echocardiography (TEE) is the method of choice for the evaluation of the left atrium and of left atrial appendage (LAA) thrombosis. However, the anatomy of the left appendage is complex and reverberations from anatomical structures may create images and ghosting which mimic left atrial thrombosis. The purpose of this study was to investigate whether a systematic approach through TEE may facilitate the recognition of LAA anatomical variants and artifacts.One hundred and sixty-four consecutive patients scheduled for cardioversion of atrial fibrillation (study population) and 30 patients (control group) undergoing mitral valve surgery were submitted to TEE using a multiplane probe in order to obtain a systematic evaluation of the LAA. The number of LAA lobes and the presence of thrombi and artifacts were evaluated.The majority of the study patients had a bilobed (53.1%) or single-lobed (34.1%) LAA. Thrombi were identified in 6%. Artifacts were found in 38 cases (23.2%) and their position was localized precisely at a distance from the transducer which was twice that from the partition-bend between the left upper pulmonary vein and left appendage, suggesting a reverberation. No differences in echocardiographic parameters were found in patients with (group 1) or without (group 2) artifacts. Cardioversion was successful in a similar percentage of cases in the two groups (group 1 68%, group 2 76%) without complications. In controls, the percentages of a single-(33%) and bilobed (40%) left appendage were similar to those found in the study population. Artifacts were identified in 11 controls (37%); no thrombi were detected during surgical left appendage inspection in these cases.A systematic approach with multiplane TEE facilitates the evaluation of the LAA anatomy and the recognition of artifacts, thus reducing the likelihood of false positive or negative diagnoses of left appendage thrombi.

Modulation of the AV node reduces the ventricular rate during AF, without affecting AV conduction during sinus rhythm. Acute and long-term results of AV node modulation in 75 patients with AF and severe related symptoms of heart failure are presented in this study. The procedure involved, in all cases, the selective ablation of the posterior inputs to the AV node; in a subgroup of 15 patients with poor modification of AV conduction properties, a sequential approach involving subsequent anterior input ablation was performed. The procedure caused acutely a prolongation of the Wenckebach cycle length (38 patients in sinus rhythm) from 334 +/- 88 to 470 +/- 80 ms (P0.01), and a reduction of the average ventricular rate (37 patients in AF) from 154 +/- 31 to 88 +/- 40 beats/min (P0.01); permanent complete AV block was induced in 9 of 75 patients (12%). Considering the "sequential" approach, an increase of the Wenckebach cycle length from 362 +/- 50 to 530 +/- 45 ms (P0.01) and a reduction of the average heart rate in patients with AF from 158 +/- 16 to 81 +/- 20 beats/min (P0.01) was obtained in this subgroup of patients, in whom the AH interval prolonged from 93 +/- 12 to 175 +/- 27 ms, and no complete AV block was observed. At a mean follow-up of 23 +/- 9 months (range 2-48), the mean number of hospital admissions per patient per year decreased from 4.2 to 0.2. Five of 49 patients with paroxysmal AF and 3 of 26 patients with chronic AF had high rate recurrences (1120 beats/min) that caused severe palpitations; these patients were considered as late clinical failures (8/75; 11%). All patients reported a substantial subjective improvement and an increased exercise tolerance, as documented by a semiquantitative questionnaire. There were no episodes of late AV block or sudden cardiac deaths. In conclusion, modulation of the AV node--either by slow pathway ablation, or by a "sequential" posterior and anterior approach in refractory patients--allows a long-term control of the ventricular rate and prevents the recurrence of severe clinical symptoms in more than 75% of patients with drug refractory AF.

We describe a rare case of intermittent dysfunction of a bileaflet mechanical aortic valve prosthesis. Subvalvular pannus overgrowth on the inflow aspect of the prosthesis impeded normal closure of one leaflet causing severe aortic regurgitation, which occurred intermittently. The complementary role of transthoracic and transesophageal echocardiography and cine-fluoroscopy in the diagnosis of this case is described.

In this study, we tested the hypothesis that hypoxic pulmonary vasoconstriction may be enhanced in systemic hypertension. The hypothesis took origin from the following two considerations: alveolar hypoxia constricts the pulmonary vessels by enhancing the Ca2+ penetration across sarcolemma of the smooth muscle cells and systemic high blood pressure is associated with an elevation of tone and reactivity of the lung vessels, which seems to depend on an excessive cytosol free Ca2+ concentration due to alterations in sodium handling and in the Na+-Ca2+ exchange system. These considerations suggest the possibility that the disorders in the biochemistry of smooth muscle contraction in hypertension facilitate the rise of cytosol Ca2+ concentration during alveolar hypoxia, thus resulting in a potentiation of the vasoconstrictor properties of this stimulus. In 43 hypertensive and 17 normotensive men, pulmonary arteriolar resistance has been evaluated during air respiration and after 15 minutes of breathing 17%, 15%, and 12% oxygen in nitrogen. Curves relating changes in pulmonary arteriolar resistance to oxygen breathing contents had similar configuration in the two populations but in hypertension were steeper and significantly shifted to the left, reflecting a lower threshold and an enhanced reactivity. This pattern was not related to differences in severity of the hypoxic stimulus, plasma catecholamine concentration, or hypocapnia and respiratory alkalosis induced by hypoxia and probably was not mediated through alpha-receptor activation. Calcium channel blockade with nifedipine was able to almost abolish both the normotensive and the hypertensive pulmonary vasoconstriction reaction. These findings support the hypothesis that hypoxic pulmonary vasoconstriction may be enhanced in systemic hypertension.(ABSTRACT TRUNCATED AT 250 WORDS)

We evaluated in patients suffering from COPD-related pulmonary hypertension whether nifedipine therapy lowers acutely and chronically pulmonary vascular pressure and resistance and whether pulmonary transmural pressure may be further lowered by the combined use of nifedipine and oxygen. Changes of the pulmonary vascular tone were determined on the pulmonary driving pressure/flow curve, which was generated by upright exercise. Fifteen patients with COPD and mean pulmonary pressure greater than or equal to 20 mm Hg were studied at control (Week 0) and after 1 wk of nifedipine treatment (180 mg daily, Week 1). It was possible to pursue the same nifedipine daily dosage for 2 months in 10 patients, who were re-evaluated after 8 wk of treatment and after nifedipine withdrawal the following week. At Week 1, mean pulmonary transmural pressure was reduced (32.8 +/- 4.1 versus 27.3 +/- 2.8 mm Hg, mean +/- SE, p less than 0.05) via active pulmonary vasodilation because the pulmonary driving pressure/flow curve was shifted right and downward. Both mean transmural pulmonary pressure lowering effect and active pulmonary vasodilatation regressed during long-term nifedipine treatment. Oxygen reduced pulmonary transmural pressure (32.8 +/- 4.1 versus 28.6 +/- 2.9 mm Hg, p less than 0.05, Week 0); however, this effect always disappeared during nifedipine treatment. We conclude that nifedipine should not be used as long-term treatment for COPD-related pulmonary hypertension and that nifedipine inhibits the oxygen capability to reduce pulmonary pressure.

Excessive vascular tone and overresponsiveness to adrenergic stimuli char acterize the hemodynamics of the greater and the lesser circulation in hyperten sion. We tested whether calcium entry blockade with verapamil (11 cases) or nifedipine (11 cases) may improve the vascular regulation in high blood pres sure. Mental arithmetic and cold were used as adrenergic activators. The former stimulus produced obvious elevation of epinephrine plasma concentra tion, increase of cardiac output (CO), slight systemic vasodilatation, pulmonary vasoconstriction, and rise of blood pressure in both circuits. After calcium an tagonists, the epinephrine reaction to the arithmetic test was significantly attenuated, variations in CO and systemic blood pressure were unchanged, pul monary vasoconstriction was abolished, and the pressure rise in the lesser cir cuit was halved. The cold pressor test increased norepinephrine plasma concen tration (NE pc), systemic and pulmonary blood pressure, and vascular resist ance and did not alter CO. The attained NE pc during cold was unvaried after verapamil and significantly enhanced after nifedipine; pressure and resistance responses of the two circuits were almost unchanged after the former, whereas systemic and pulmonary vascular resistance rises were importantly attenuated after the latter compound, resulting in much lower pressure reactivity. A modulation of the sympathoadrenal reaction, per se, can explain changes in the systemic and in the pulmonary vasomotion with calcium blockade during arithmetic. It would seem that after verapamil the sympathetic system was still activated during cold to such an extent as to maintain the same vasoconstrictor potency. NE pc suggests that the sympathetic discharge was not reduced by nifedipine. The impressive attenuation of the constrictor reaction in the two circuits would imply the existence of a shared vascular disorder in which cal cium ions are involved, which is more sensitive to nifedipine.

1. In systemic hypertension the pulmonary vessels show an excessive tone at rest and hyper-react to adrenoceptor stimulation. Alterations in Ca2+ handling by the vascular smooth muscle cells seem to underlie these disorders. Alveolar hypoxia also constricts pulmonary arteries, increasing the intracellular Ca2+ availability for smooth muscle contraction. This suggests the hypothesis that hypoxic pulmonary vasoconstriction depends on similar biochemical disorders, and that the response to the hypoxic stimulus may be emphasized in high blood pressure. 2. In 21 hypertensive and 10 normotensive men, pulmonary arterial pressure and arteriolar resistance have been evaluated during air respiration and after 15 min of breathing 17, 15 and 12% oxygen in nitrogen. Curves relating changes in pulmonary arterial pressure and arteriolar resistance to the oxygen content of inspired gas had a similar configuration in the two populations, but in hypertension were steeper and significantly shifted to the left of those in normotension, reflecting a lower threshold and an enhanced vasoconstrictor reactivity. 3. This pattern was not related to differences in severity of the hypoxic stimulus, degree of hypocapnia and respiratory alkalosis induced by hypoxia, and plasma catecholamines. 4. The association of high blood pressure with enhanced pulmonary vasoreactivity to alveolar hypoxia could have clinical implications in patients who are chronically hypoxic and have systemic hypertension.

This study was undertaken to test whether the emphasized systemic vasomotion during sympathetic activation in hypertension is shared by the pulmonary circulation. To this end, 10 normotensive and 29 primary hypertensive subjects were investigated during adrenergic stimulation by mental arithmetic and cold pressor test. Both stimuli induced a systemic pressor reaction in both groups, which was mediated through an increase in cardiac output and a mild reduction in vascular resistance during arithmetic and through a predominant rise in systemic vascular resistance during cold. Each of these changes was emphasized in the hypertensive population as compared with the normotensive one. Pressure in the pulmonary artery remained unchanged during cold and was slightly raised (systolic) during arithmetic in normotensive subjects. On the contrary, in hypertensive subjects systolic and diastolic pulmonary pressures were consistently augmented by both stimuli, and pulmonary arteriolar resistance (dyn sec cm-5) rose from 92 in the baseline to 125 (p less than 0.01) during arithmetic and to 124 (p less than 0.01) during the cold test. This reaction is interpreted as reflecting a neurally mediated vasoconstriction and not as the consequence of mechanical or chemical changes, since no difference was observed in pulmonary wedge pressure, pleural pressure, arterial blood gas levels, and pH between controls and hypertensive subjects in the steady state and during either stressful stimulation. Baseline pulmonary arteriolar resistance was also found to correlate positively with systemic vascular resistance in the hypertensive group. When pressure changes occurred, the time course was similar in the two circuits; resistance increased to a proportionally similar degree in the two districts during the cold stimulus.(ABSTRACT TRUNCATED AT 250 WORDS)