Feasibility study of a mixed reality tool for real 3D visualization and planning of left atrial appendage occlusion.

In left atrial appendage occlusion (LAAO), pre-procedural imaging is pivotal to describe the highly variable LAA anatomy and to guide the operator in device sizing and interventional planning. Multiplanar reconstruction and 3D rendering are used for the interpretation of 3D CT datasets. However, this method of review of such imaging, which is mediated by 2D screens, may be limited due to the lack of true 3D visualization of the structures of interest; Mixed Reality (MxR) may further improve the CT-based pre-procedural planning by allowing for real-3D visualizations with holographic replicas of anatomical models. In this manuscript we present a novel software based on MxR and we evaluated its feasibility on different LAA morphologies. The morphological analysis of the holographic anatomical models was successfully applied for all the patients (n â€‹= â€‹4) independently from the morphology and it was performed in less than 10 minutes. Our findings suggest that with further developments MxR could have the potential to become a pivotal tool in LAA occlusion planning thanks to the real-3D perception, possibly leading to a more accurate and faster planning phase.

Complex odontoma at the upper right maxilla: Surgical management and histomorphological profile.

BACKGROUND: Odontomas are hamartomatous developmental malformations of the dental tissues. Usually asymptomatic, their presence is often revealed on routine radiographs. The study aimed to establish the efficacy of this conventional approach in treating odontomas, analysing clinical outcome, follow-up, and histomorphological profile. CASE REPORT: A case is presented with a review of the international literature. The patient, aged 8 years, had a complex odontoma localised on the front upper jaw. She was treated following the conventional surgical procedure. Post-operative course and healing were uneventful. Orthodontic treatment was necessary to realign the teeth. At the 12-month follow-up there was no recurrence or failure. Healing was excellent. CONCLUSION: Variations in normal tooth eruption are a common finding, but significant deviations from established norms should alert the clinician to further investigate the patient's health and development.

P594Contrast transthoracic echocardiography as a gatekeeper for patent foramen ovale closure.

BACKGROUND.: The presence of patent foramen ovale (PFO) has been linked to many illness, including cryptogenic stroke, transient ischemic attack, migraine, platypnea-orthodeoxia syndrome and decompression sickness in scuba divers. Transesophageal echocardiography is the gold standard technique for the visualization of atrial septal anatomy, but it is a secondary level exam, not always available, with additional associated costs and not completely free from procedural risks. Standard transthoracic echocardiography (TTE) has a too low sensitivity for PFO screening. PURPOSE.: The aim of the study was to assess the role of TTE associated with agitated saline contrast injection (contrast-TTE) as a gatekeeper for the identification of PFO in a large cohort of patients undergoing selection for percutaneous closure. METHODS.: A total of 200 patients undergoing a diagnostic work-up for the identification of PFO was imaged by contrast-TTE at rest and after provocative maneuvers (PM: Valsalva in all cases). Contrast TTE was graded from 0 to 4 on the bases of bubbles counting (0: no bubbles; 1: < 10 bubbles; 2: 10-30 bubbles; 3: >30 bubbles; 4: complete LV opacification). PFO closure was performed after a consensual clinical decision by the cardiologist and the neurologist taking into account comprehensive imaging, clinical evaluation and thrombophilia screening. PFO closure was always monitored by intracardiac echocardiography. RESULTS.: At baseline contrast TTE was positive (≥2) in 34 patients (17%) while contrast TTE with PM was positive in 94 cases (47%). 27 out of 200 patients (14%) had an interatrial septal aneurysms. PFO closure was performed in 34 cases (17%). All of these had severe right-to-left shunting (≥3) at contrast TTE and 9 cases had also an interatrial septal aneurysms. The procedure was aborted in only 1 patient due to a complex defect anatomy. CONCLUSION.: Contrast TTE with PM may be not only considered an accurate tool for the detection of PFO but may be also inserted in the diagnostic work- up as a primary gatekeeper for percutaneous closure. Severe shunting at contrast TTE influences final decision making in a large cohort of cases undergoing screening for PFO closure.

How the two sides of the heart adapt to graded impedance to venous return with head-up tilting.

OBJECTIVES: The study sought to probe whether the adaptation of the right ventricle to reduced preload may influence that of the left ventricle (interdependence) and whether and how this mechanism contributes to maintain an adequate pump function. BACKGROUND: A study like this requires that subjects be normal, restraint of venous return be gradual, systolic function and diastolic filling and dimensions of either ventricle be monitored. METHODS: Of 30 healthy men (mean [+/- SD] age 35 +/- 7 years) studied with Doppler echocardiography, 20 were studied in the supine position and after 20 degrees, 40 degrees and 60 degrees tilting for 10 min; the remaining 10 subjects were also studied at the same levels of tilting for 45 min. RESULTS: At 20 degrees, heart rate, blood pressure and stroke volume were steady; the diastolic right ventricular area was reduced (p < 0.001); and the end-diastolic dimension of the left ventricle did not vary. Tilting at 40 degrees and 60 degrees increased heart rate and diastolic pressure, decreased systolic pressure and stroke volume and reduced the diastolic dimensions of both ventricles. At any tilting level, right and left peak early inflow velocities (E) were decreased, peak late velocities (A) were unchanged, and E/A ratios were reduced, suggesting that the atrial-ventricular pressure difference was diminished bilaterally and that the atrial contribution to ventricular filling was maintained. Tachycardia at 40 degrees and 60 degrees tilting was not associated with enhancement of left ventricular fiber fractional shortening or mean velocity of shortening for any corresponding end-systolic wall stress; changes in heart rate also did not correlate with those in fiber fractional shortening and velocity of shortening. The adaptive responses to the same degrees of tilting for a duration of 45 min were comparable to those at 10 min. CONCLUSIONS: With moderate restraint of venous return, the left ventricle maintains filling and output in response to a reduction in right ventricular diastolic volume, which increases left ventricular compliance (interdependence), and to the pulmonary blood reservoir, which compensates for an immediate decrease in right ventricular stroke volume. The decreased lung blood volume would facilitate right ventricular ejection, resulting in a normal stroke output despite the reduced preload. Thus, mechanical adjustments fully compensate for moderate reduction of venous return. A more severe reduction requires chronotropic support for the maintenance of cardiac output. With prolongation of tilting time to 45 min, adaptive mechanisms do not become exhausted in normal persons.

How the left and right sides of the heart, as well as pulmonary venous drainage, adapt to an increasing degree of head-up tilting in hypertrophic cardiomyopathy: differences from the normal heart.

OBJECTIVES: We aimed to assess the differences in the adaptive response of patients with hypertrophic cardiomyopathy (HCM) compared with normal subjects, as well as any association with increased susceptibility to the test. BACKGROUND: Diastolic function contributes importantly in the adaptation of the normal heart to head-up tilting. This mechanism may be disturbed by an impaired relaxation in HCM. METHODS: Twenty-one male patients with HCM (46 +/- 6 years old) and 22 healthy men (44 +/- 8 years) were studied using Doppler echocardiography after 1 and 10 min of head-up tilting at 20 degrees, 40 degrees and 60 degrees. RESULTS: In control subjects, tilting was associated with 1) a predominance of diastolic pulmonary venous flow and early left ventricular (LV) filling (atrium functioning as an open conduit); 2) right ventricular (RV) shrinkage; and 3) no LV dimensional variations. In patients with HCM, tilting was associated with 1) a prevalence of systolic pulmonary venous flow (atrium functioning as a reservoir in which filling depends on atrial relaxation and compliance) and late diastolic transmitral flow (atrium working as a booster pump); 2) LV shrinkage; and 3) no RV dimension variations. These mechanisms did not prevent stroke volume (SV) from decreasing at 40 degrees and 60 degrees in both groups. Because of a lower increase in heart rate (HR), a reduction in cardiac output (CO) was greater in patients with HCM. The responses were similar after 1 and 10 min of tilting in control subjects, whereas in patients, blood pressure (BP), SV and LV dimension fell more after 10 min. CONCLUSIONS: Adaptation of the normal heart to tilting is based on a ventricular interaction and LV diastolic properties; HCM relies on left atrial diastolic and systolic functions. An inadequate HR reaction to a fall in BP and SV in HCM (depressed reflexogenic activity) contributes to making CO more vulnerable by greater and more prolonged displacements.

Cardiac hypertrophy in hypertension. Repolarization abnormalities elicited by rapid lowering of pressure.

In hypertension, coronary flow is augmented and oxygen balance is adequate despite an increase in coronary resistance. For the maintenance of flow in the presence of and after regression of ventricular hypertrophy, the ratio of pressure and ventricular mass must remain normal. Coronary reserve would be altered if treatment normalized pressure but not ventricular mass or if pressure were lowered too fast. We investigated 42 patients with primary hypertension. In 28 (Group I) left ventricular mass index (by ultrasound) was within the mean value +2 SD (96 + 38 g/m2) of 145 controls and exceeded these values in the remaining 14 patients (Group 2). The diastolic pressure was lowered rapidly to between 85 and 90 mm Hg with two potent vasodilators, nifedipine (sublingually) and nitroprusside, while a 12-lead electrocardiogram was recorded continuously. During both tests, seven patients in Group 2 (responders) showed inversion of normal T waves, in lead I, aVL, and V3-6. These changes waxed and waned in parallel with the pressure fall and recovery and were not attributable to alterations in adrenergic tone, conduction disturbances, variations, or group differences in the QRS axis, QTc interval, heart rate, left ventricular fractional shortening, wall stress, rate of dimension increase in early diastole, or isovolumic relaxation. A ""steal phenomenon'' or passive collapse in compliant coronary lesions during vasodilatation seems unlikely; in fact, patients were free from coronary symptoms, and the electrocardiographic alterations occurred only in seven patients in Group 2, who had a greater left ventricular mass index and required a larger pressure drop to return the diastolic pressure to normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Influences of aortic pressure gradient and ventricular septal thickness with systolic coronary flow in aortic valve stenosis.

This study evaluates flow patterns of the left anterior descending and circumflex coronary arteries by multiplane transesophageal echocardiography in 25 patients with aortic valve stenosis, and assesses the relation between coronary flow characteristics and anatomic and hemodynamic parameters.

The influence of diastolic and systolic function on exercise performance in heart failure due to dilated cardiomyopathy or ischemic heart disease.

BACKGROUND: Peripheral adaptations and ventricular abnormalities influence physical performance in chronic heart failure. However, the role of the heart in determining exercise capacity has not been completely elucidated. AIMS: To define cardiac determinants of exercise capacity in patients with dilated cardiomyopathy. METHODS: In 101 patients with heart failure (NYHA class II-III) due to primary or ischemic dilated cardiomyopathy we measured peak exercise oxygen consumption (Pvo2), left ventricular ejection fraction (EF), left and right atrial and ventricular cavity dimensions, mitral and tricuspid flows. Patients were subdivided in class A (Pvo2 > 20 ml/min per kg; n = 44), class B (Pvo2 16-20 ml/min per kg; n = 42) and class C (Pvo2 < 16 ml/min per kg; n = 15). RESULTS: Left ventricular diastolic and systolic dimensions, left atrial diameter, right atrial and ventricular areas were greater in class C than in class B and A; EF was lower in class C than in the other two classes; mitral peak flow velocity at early diastole (PFVE) and the ratio between early and late peak flow velocity (PFVE/PFVA) were higher in class C; mitral and tricuspid deceleration time (DT) in class B and A significantly exceeded those in class C. Peak vo2 was correlated with left and right ventricular dimensions, left atrial diameter, EF, mitral PFVE and PFVE/PFVA, mitral and tricuspid DT. Left ventricular EF, DT of the mitral valve and left ventricular diastolic diameter were independent predictors of peak vo2 at multivariate analysis. CONCLUSIONS: In patients with dilated cardiomyopathy Pvo2 is related to left and right ventricular dimensions, left and right ventricular filling pattern and EF. Both systolic and diastolic dysfunction influence functional capacity.

Exercise echocardiography versus exercise electrocardiography in the diagnosis of coronary artery disease in hypertension.

In hypertension, coronary artery disease (CAD) can be overestimated by stress electrocardiography (ECG) and scintigraphy due to frequent false-positive results. Exercise tests are also limited by an excessive blood pressure increase, and pharmacologic pressure normalization decreases the accuracy of the test. The aim of this study was to assess the accuracy of exercise echocardiography as an alternative test for CAD detection in hypertension, both before and after adequate blood pressure control. We studied 59 hypertensive and 59 normotensive patients undergoing coronary angiography for chest pain. Upright bicycle exercise ECG and echocardiographic tests were performed in each group in the absence of therapy; in hypertensives, the tests were repeated a day apart after blood pressure normalization with sublingual nifedipine. Significant CAD (lumen narrowing >50%) was detected in 22 hypertensive and 41 normotensive patients. In the two groups, sensitivity, specificity, and diagnostic accuracy of exercise echocardiography performed before treatment were not statistically different (95%, 94%, 94% in hypertensives and 82%, 77%, 83% in normotensives, respectively), but were significantly higher than for the exercise ECG test (68%, 70%, and 69%, respectively). After blood pressure lowering, exercise echocardiography sensitivity slightly decreased (91%), whereas specificity (100%) and diagnostic accuracy (96%) did not vary; on the contrary, exercise ECG sensitivity decreased to 45%. Therefore, according to our data, exercise echocardiography can be an accurate test and more reliable than exercise ECG to detect CAD in normotensives as well as in hypertensives. Normalization of blood pressure with nifedipine does not affect its accuracy, but markedly reduces the sensitivity of exercise ECG.

Relation between exercise-induced left ventricular wall motion abnormalities and coronary artery disease in hypertensive patients: effects of blood pressure normalization.

In hypertension, several factors disturb coronary circulation and the metabolic reserve of the heart. This study was undertaken to test whether in hypertensive patients global and regional left ventricular (LV) function is related during exercise to the presence of significant coronary stenosis and whether lowering of coronary perfusion pressure through rapid normalization of the diastolic pressure may modify the dynamics of the left ventricle. Thirty-five patients with mild to moderate hypertension undergoing coronary angiography for the evaluation of chest pain were included in the study; upright bicycle exercise echocardiography tests were performed without therapy and 1 day later 1 h after sublingual administration of nifedipine. LV ejection fraction and regional wall motion scores were evaluated and compared at baseline, peak exercise, immediate postexercise, and recovery phases in each test through digital on-line storing of echocardiographic images. Twenty-one patients had normal coronary arteries (group 1) and 14 significant coronary stenoses (group 2); age, gender, heart rate, blood pressure, left ventricular diameter and mass index, and ejection fraction were similar in the two groups. At peak exercise LV ejection fraction slightly increased in group 1, whereas it slightly decreased in group 2 (both during the test without therapy and after nifedipine administration). All patients in group 1 had normal left ventricular wall motion during exercise; 13 of 14 patients in group 2 had LV wall motion abnormalities at peak exercise. Nifedipine did not produce any effect on LV regional wall motion in group 1, but it induced significant changes in LV regional wall motion in seven patients in group 2. Changes in LV wall motion between the two test groups were related to the number of the stenotic coronary vessels: the normal exercise test before and after therapy and the two normalized tests after nifedipine administration were in fact observed in patients with one-vessel disease, whereas worsening or changes in the site of ischemia were observed only in patients with multivessel disease. Regional and global left ventricular dynamics during exercise is mainly dependent on the existence of significant coronary artery disease. Rapid decrease of blood pressure does not alter the regional dynamics of the left ventricle during exercise in patients without coronary artery disease, but it may induce normalization, worsening, or changes in the site of wall motion abnormalities in hypertensives with significant coronary stenoses.

Isolated noncompaction of the myocardium: multiplane transesophageal echocardiography diagnosis in an adult.

We describe a case of isolated noncompaction of the myocardium in a 66-year-old patient. Peculiar anatomic features of this disease were clearly suspected on transthoracic echocardiography and precisely recognized through transesophageal echocardiography. The role of transthoracic and transesophageal echocardiography in the detection of this rare disease is described in this report.

Lowering of blood pressure and coronary blood flow in isolated systolic hypertension.

BACKGROUND: In essential hypertension, the lower limit of autoregulation of coronary flow shifts to higher perfusion and the hypertensive ventricle is at a higher than normal risk of ischemia, and less able to tolerate acute reduction of coronary perfusion pressure. Little is known about pattern of coronary flow in isolated systolic hypertension, a pathologic condition in which the elevated systolic blood pressure is associated with a lower than normal vascular compliance and normal or slightly greater than normal mean arterial pressure and vascular resistance. OBJECTIVE: To evaluate the effects of rapid normalization of blood pressure on coronary blood flow in isolated systolic hypertension. METHODS: We subjected 20 patients with isolated systolic hypertension to intraoperative hemodynamic and transesophageal echocardiographic monitoring during peripheral vascular surgery. Coronary flow velocity integrals and diameters in the left anterior descending coronary artery were evaluated under baseline conditions and after normalization of blood pressure, which occurred spontaneously during anesthesia (10 cases; group 1A) or was induced by infusion of nitrate (10 cases, group 1B). RESULTS: After normalization of systolic blood pressure integrals decreased significantly only for patients in group 1A; percentage changes of diameter were significantly greater for patients in group 1B. Therefore, coronary blood flow after normalization of systolic blood pressure increased for patients in group 1B (by 28+/-25%) and decreased for patients in group 1A (by 30+/-21%). Changes in integrals were inversely related to those in diameter (r= -0.72, P < 0.001); for patients in group 1A changes in coronary perfusion pressure and diameter were related to those of integrals (r= 0.94; P < 0.0005). CONCLUSIONS: In isolated systolic hypertension, despite there being similar changes of the systolic blood pressure, administration of nitrates caused a marked increase of coronary flow through direct effects on coronary circulation, whereas spontaneous normotension was associated with a significant reduction of coronary flow.

Doppler and echocardiographic diagnosis of a free-floating left atrial thrombus.

We report a case of a free-floating left atrial thrombus in a patient with severe mitral stenosis diagnosed by cross-sectional echocardiography. The Doppler technique was very useful in explaining some peculiar auscultatory and clinical aspects present in this rare complication of mitral valvar stenosis.

Diastolic ventricular interaction in normal and dilated heart during head-up tilting.

BACKGROUND: The normal human heart behaves as a single functional unit during preload reduction; adaptations of the left ventricle to head-up tilting is mediated through ventricular interdependence and biventricular-lung interaction. HYPOTHESIS: We hypothesized that reduction of venous return in dilated cardiomyopathy is likely to have a great effect on ventricular chamber geometry and filling. The aim of this study was to evaluate the effects of gradual head-up tilting in normal subjects and in patients with dilated cardiomyopathy, addressing special attention to right (RV) and left ventricular (LV) dimensions, geometry, and filling, and to biventricular-lung interaction. METHODS: Twenty normal subjects and 23 patients with moderate heart failure due to dilated cardiomyopathy were studied with two-dimensional and Doppler echocardiography in supine position and after 20 degrees, 40 degrees, and 60 degrees tilting. Right ventricular and LV dimensions, LV geometry, and tricuspid, mitral, and pulmonary venous flow patterns were recorded at each step of the study. Geometric changes of the LV were evaluated by measurements of volumes and diameters in the apical four-chamber view (which identifies the interventricular septum and lateral wall) and apical two-chamber view (which identifies the inferior and anterior wall of the LV). RESULTS: In the two groups, tilting was associated with reduction of RV area and LV diameter and volumes; percent variations in LV diameter and volumes recorded in four-chamber view were lower at each step of tilting than with those derived from the two-chamber view in controls and in patients. In normal subjects, mitral and tricuspid peak early flow velocities were decreased at any tilting level; peak late velocities were unchanged; peak velocity of systolic forward flow of the pulmonary vein was reduced, diastolic forward flow was unchanged, and the difference in duration between reverse pulmonary flow and forward mitral A wave was reduced. Doppler findings were qualitatively similar in patients, but tilting induced a more marked redistribution of LV filling to late diastole because of a significant increase in atrial contribution. CONCLUSIONS: Preload reduction by tilting induces profound effects on left and right dimensions, geometry, and filling in normal and dilated heart; reduction or RV dimensions are associated with changes in LV ventricular geometry (minimal reduction in septal-lateral diameter, marked reduction in anterior-posterior diameter), redistribution of right and left diastolic filling to late diastole, and redistribution of pulmonary venous flow to early diastole. These mechanisms are probably due to a favorable interaction between heart and lungs, which increases compliance within the pericardial space and facilitates redistribution of flow from the lungs. Even a minimal amount of preload reduction causes more marked effects in LV filling patterns in dilated cardiomyopathy than in normal hearts, confirming that ventricular interaction and pericardial constraint are increased when heart volume enlarges.

Changes in systemic and pulmonary vascular reactivity in hypertension following nifedipine and verapamil.

Excessive vascular tone and overresponsiveness to adrenergic stimuli characterize the hemodynamics of the greater and the lesser circulation in hypertension. We tested whether calcium entry blockade with verapamil (11 cases) or nifedipine (11 cases) may improve the vascular regulation in high blood pressure. Mental arithmetic and cold were used as adrenergic activators. The former stimulus produced obvious elevation of epinephrine plasma concentration, increase of cardiac output (CO), slight systemic vasodilatation, pulmonary vasoconstriction, and rise of blood pressure in both circuits. After calcium antagonists, the epinephrine reaction to the arithmetic test was significantly attenuated, variations in CO and systemic blood pressure were unchanged, pulmonary vasoconstriction was abolished, and the pressure rise in the lesser circuit was halved. The cold pressor test increased norepinephrine plasma concentration (NE pc), systemic and pulmonary blood pressure, and vascular resistance 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Usefulness of transoesophageal echocardiography before cardioversion in patients with atrial fibrillation and different anticoagulant regimens.

OBJECTIVES: To evaluate the prevalence of atrial thrombi in patients with atrial fibrillation undergoing different anticoagulation regimens before cardioversion; to evaluate the usefulness of transoesophageal echocardiography (TOE) guided cardioversion to prevent thromboembolic complications; and to correlate the presence of atrial thrombi with clinical and echocardiographic data. METHODS: 757 consecutive patients admitted as candidates for cardioversion of atrial fibrillation were enrolled in the study. They were divided into four groups: effective conventional oral anticoagulation, short term anticoagulation, ineffective oral anticoagulation or subtherapeutic anticoagulation, and effective oral anticoagulation with a duration of < 3 weeks for various clinical reasons. All patients underwent TOE before cardioversion; in the presence of atrial thrombi or extreme left atrial echo contrast, cardioversion was postponed. The incidence of thromboembolic events was evaluated after cardioversion. RESULTS: Atrial thrombi were detected in 48 of the 757 (6.3%) patients. No significant differences in the percentage of atrial thrombosis were found in the four study groups. Patients with atrial thrombosis were older and had a higher percentage of mitral prosthetic valves, lower left ventricular ejection fraction, more severe atrial spontaneous echo contrast, and lower Doppler left atrial appendage velocities. 648 patients were scheduled for cardioversion. Cardioversion was successful in 89% of patients without any major thromboembolic event. CONCLUSIONS: The prevalence of atrial thrombosis before cardioversion despite different treatments with anticoagulants is about 7% and a TOE guided approach may prevent the risk of embolic events.

Changes in pulmonary venous return during head-up tilting in man.

1. In a supine position, the heart fills to close to the limits of pericardial constraint and the pericardium may act to redistribute central blood volume from the left side of the heart back to the more compliant lung. 2. We probed whether, and through which mechanisms, a redistribution of blood from the lungs to the left heart occurs during vertical displacement and compensates for reduced venous return. 3. We investigated 16 normal volunteers with Doppler-echocardiography during 20 degrees, 40 degrees and 60 degrees head-up tilting. Tilting was stopped at 10 min in 10 subjects (group 1) and at 45 min in 6 subjects (group 2). 4. At 10 min we observed a reduction in right ventricular diastolic dimension and left ventricular end-diastolic pressure, as estimated by the difference between the duration of the pulmonary venous flow during atrial contraction (Z wave) and that of the mitral A wave. We also recorded a decrease during systole (X wave) and an increase during diastole (Y wave) of the pulmonary venous forward flow velocity. These variations were evident at 20 degrees and became progressively greater with increasing degrees of tilting. In group 2, changes at 10 min and at 45 min for any degree of displacement were similar. 5. A decrease in right ventricular dimensions (ventricular interdependence) and underfilling of the lung compartment due to volume redistribution to the periphery (diminished lung contribution to pericardial constraint) augment compliance within the pericardial space, reduce downstream pressure for pulmonary venous return and move the pulmonary venous flow predominantly to ventricular diastole, allowing diastolic filling. 6. During head-up tilting a favourable interaction between heart and lungs increases compliance within the pericardial space and facilitates redistribution of blood from the lungs, resulting in a sustained compensation for the reduced venous return.

[Biventricular-pulmonary interaction as the prime mechanism in the adaptation of the human heart to orthostatic posture]. / Interazione biventricolo-polmonare quale primo meccanismo di adattamento del cuore umano alla posizione ortostatica.

The purpose was to identify the basic circulatory adjustments to the erect position in man and what the role may be of the heart-lung coupling. Requirements for this study are that: subjects be normal, changes in posture be gradual; pulmonary venous flow, ventricular filling and output be assessed; the methods be noninvasive. In 10 normal men (mean age 34 +/- 8 years) the flow pattern in the right upper pulmonary vein and through the atrioventricular mitral valve, and the right and left ventricular (RV and LV) end-diastolic dimensions were assessed with Doppler echocardiography, in the supine position, after 20, 40 and 60 degrees tilting for 10 min. At 20 degrees displacement: blood pressure, heart rate, stroke volume and LV dimension did not change: RV dimension reduced: pulmonary venous forward flow velocity diminished during systole (X wave) and rose in diastole (Y wave); E wave velocity of the mitral flow and the E/A ratio reduced (consistent with a lower atrioventricular pressure gradient); difference between duration of the pulmonary venous flow reversal during atrial contraction (Z wave) and duration of the mitral A wave (the difference is an index of LV end-diastolic pressure) also diminished, suggesting an improvement of LV compliance. Tilting at 40 and 60 degrees were associated with increase in heart rate and diastolic blood pressure; decrease in systolic blood pressure and stroke volume; reduction of diastolic dimension of both ventricles; some enhancement of the flow changes already described. X was related to stroke volume while supine (r = 0.75; p < 0.01) and not during tilting; at any level of tilting, X/Y ratio was inversely related to the E/A ratio and directly related to the difference in duration between Z and A. During vertical displacement, blood shifts from lungs to systemic circulation resulting in: contribution to replenishment of the arterial side of the circuit; enhancement in LV compliance, due to reduction of RV diastolic volume (interdependence) and pericardial constraint; facilitation and predominance of blood drainage for the lungs during ventricular diastole. Thus, the basic adaptation to erect positioning in man seems to be a mechanical one, mainly consisting of an interplay between heart and lungs. Increase in heart rate and vasoconstriction appear to be supportive mechanisms at more vertical postures.

Electrocardiographic alterations suggestive of myocardial injury elicited by rapid pressure lowering in hypertension.

In hypertensive cardiac hypertrophy, the elevated coronary perfusion pressure compensates importantly for the raised coronary resistance. An imbalance between perfusion and left ventricular (LV) mass, such as that occurring with rapid or excessive blood pressure lowering, may result in an inadequate oxygen supply. In 28 primary hypertensives (Group A) with LV mass index within the mean + 1 SD (96 + 19 g m-2) of 145 controls, and in 26 patients whose LV mass exceeded these values (Group B), we lowered the diastolic blood pressure rapidly to 85-90 mmHg, using both s.l. nifedipine and i.v. nitroprusside. During each test, eight patients in Group B had inversion of T waves in lead I, aVL, V3-V6, which waxed and waned in parallel with the pressure fall and recovery, and was independent of conduction disturbances, variations or group differences in the QRS axis, QTc interval, heart rate, LV fractional shortening and wall stress. A 'coronary steal phenomenon' or passive collapse in compliant lesions consequent to vasodilatation may trigger acute myocardial ischaemia in the presence of severe coronary disease. Patients developing the ECG alterations, however, were free from angina and four, who were subjected to coronary angiography, had normal arteriograms. Patients with the myocardial injury pattern showed greater LV mass indices and larger falls in diastolic pressure for it to reach normal levels. The supply of energy to the hypertrophied hypertensive heart seems to depend importantly on the coronary perfusion pressure, suggesting the cautious use of rapid acting drugs.