EFFECTS OF MITRAL-VALVE REPLACEMENT ON THE PULMONARY VASCULAR DYNAMICS OF PATIENTS WITH PULMONARY HYPERTENSION

Haemodynamic contributors to pulmonary hypertension across the spectrum of adult congenital heart disease

AIMS

Adult congenital heart disease (ACHD) includes multiple disease states that predispose to pulmonary hypertension (PH). Haemodynamically, PH depends on abnormalities in three components: pulmonary blood flow (Qp), pulmonary vascular resistance (PVR) and pulmonary venous pressure (PVP). We sought to evaluate the prevalence and prognostic impact of individual haemodynamic abnormalities in ACHD.

METHODS AND RESULTS

Retrospective study of ACHD patients undergoing cardiac catheterization at Mayo Clinic between 1999 and 2022 who were followed for the combined endpoint of death/heart transplantation. Among 1005 patients, 37% had mean pulmonary artery pressure (mPAP) ≥25 mmHg with more systemic ventricular disease, cyanotic disease and shunt lesions, highest N-terminal pro-B-type natriuretic peptide and worse right heart remodelling/dysfunction. Among those with biventricular circulation, elevated PVP, PVR and mPAP were associated with prognosis, but not increased Qp >8 L/min. However, risk of death/transplant increased for PVR only at ≥3 Wood units (hazard ratio [HR] 3.00, 95% confidence interval [CI] 2.17-4.15; p < 0.0001) and for mPAP only at ≥25 mmHg (HR 3.15, 95% CI 2.17-4.58; p < 0.0001), not at current recommended lower cutpoints. Combined abnormalities in PVP and PVR were associated with worst outcome (HR 5.20, 95% CI 3.55-7.63; p < 0.0001) with intermediate risk with either abnormality (HR 2.11, 95% CI 1.46-3.04; p < 0.0001). Findings were consistent across type of biventricular ACHD. Only with the Fontan (univentricular) circulation was a lower mPAP threshold (20 mmHg) associated with adverse outcomes.

CONCLUSIONS

Elevation of mPAP ≥25 mmHg in ACHD with a biventricular circulation is prognostically important regardless of disease phenotype, but milder PH of 21-25 mmHg is not associated with adverse outcome unless associated with Fontan circulation. Elevation in PVP >15 mmHg and PVR ≥3 Wood units were each individually associated with mortality with combined abnormalities associated with greatest risk. Categorizing PH in ACHD by haemodynamic mechanism (PVR, PVP or Qp) allows meaningful prognostication, and may allow more unified study of targeted therapies across heterogeneous disease states in ACHD.

Dynamic Mitral Regurgitation-An Easy to Miss Reversible Cause of Severe Pulmonary Vascular Remodeling

Respirophasic MR in HFrEF with severe pulmonary vascular disease and low output heart failure– Is there a role for treating the MR? @yreddyhf @BrendenIngraham @mayoclinicCV

Pulmonary Hypertension in Left Heart Disease

Pulmonary hypertension is common in left heart disease and is related most commonly to passive back transmission of elevated left atrial pressures. Some patients, however, may develop pulmonary vascular remodeling superimposed on their left-sided heart disease. This review provides a contemporary appraisal of existing criteria to diagnose a precapillary component to pulmonary hypertension in left heart disease as well as discusses etiologies, management issues, and future directions.

Nonresponse to Acute Vasodilator Challenge and Prognosis in Heart Failure With Pulmonary Hypertension

BACKGROUND

An acute vasodilator challenge is recommended in patients with heart failure and pulmonary hypertension during heart transplant evaluation. The aim of the study was to assess which hemodynamic parameters are associated with nonresponsiveness to the challenge.

METHODS AND RESULTS

This study is a retrospective analysis of 402 patients with heart failure with pulmonary hypertension who underwent right heart catheterization and a pulmonary vasodilator challenge. Among the 140 who fulfilled the transplant guidelines eligibility criteria for the vasodilator challenge, 38 were responders and 102 nonresponders. At multivariable analysis, a diastolic blood pressure of <70 mm Hg, pulmonary vascular resistance of >5 Woods units, and pulmonary artery compliance of <1.2 mL/mm Hg were independently associated with poor response to vasodilator challenge (all P < .001). The presence of any 2 of these 3 conditions was associated with a 90% probability of being a nonresponder. The covariate-adjusted hemodynamic predictors of death in the entire population were a low baseline systolic blood pressure (P = .0017) and a low baseline right ventricular stroke work index (P = .0395).

CONCLUSIONS

In patients with heart failure and pulmonary hypertension, low pulmonary arterial compliance, high pulmonary vascular resistance, and low diastolic blood pressure predict the nonresponsiveness to acute vasodilator challenge whilst a poor right ventricular function predicts a dismal prognosis.

Hemodynamics in Adults With the Shone Complex

Patients with Shone complex (SC) have multiple left-sided obstructive lesions and thus are at risk for left ventricular (LV) remodeling, LV diastolic dysfunction and pulmonary hypertension. Yet, to date, there has been no description of hemodynamics in adults with SC. Retrospective chart review of 25 patients with SC who underwent cardiac catheterization at Mayo Clinic, MN between 2002 and 2019 was performed. SC was defined as multiple left-sided obstructive lesions in the presence of an anatomically abnormal mitral valve. Median age was 32 years (22.5, 42) and 15 patients (60%) were female. The majority of patients (84%) had history of coarctation of the aorta, 10 (40%) had subaortic stenosis, 11 (44%) had prior aortic valve replacement, and 10 (40%) had prior mitral valve replacement. Structural disease at the time of catheterization which warranted intervention within the next year was present in 13 patients (52%). The mean LV end-diastolic pressure was 21.3 ± 9.0 mm Hg (>15 mm Hg in 71%), pulmonary artery peak systolic pressure was 55.4 ± 13.4 mm Hg, and the pulmonary artery mean pressure was 37.0 ± 9.4 mm Hg (>20 mm Hg in 96%). During a mean follow-up of 8.3 ± 4.4 years, there were 7 deaths (28%) and 3 additional patients (12%) underwent cardiac transplantation. In conclusion, adults with SC who underwent catheterization showed significant left-sided heart and pulmonary vascular remodeling. Elevated LV end-diastolic pressure and pulmonary artery pressures were highly prevalent. There were high mortality and cardiac transplant rates in our cohort.

Pulmonary Hypertension by the Method of Paul Wood

A physiological approach to the analysis of hemodynamic data in pulmonary hypertension (PH) has the advantage of reducing the large number (well over 100) of potential causal illnesses into four simple mechanisms. A fifth condition is composed of mixtures of the four basic mechanisms. This approach was beautifully described by Paul Wood, the great cardiologist whose name is given to the units of pulmonary vascular resistance (PVR), Wood units. This approach uses well understood physiological contributions to pulmonary vascular pressure. It is powerful, the major uncertainty being in determination of the magnitude of each mechanism in patients that have mixed PH of several causes. It also makes sense of the occasionally awkward clustering of conditions in the clinical classification of the World Symposium, which omits pulmonary vasoconstriction, hyperkinetic states, and the highly prevalent condition of "mixed" PH. This method of analysis is described and demonstrated, much as Wood did in his writings. The method is useful in the office, the ICU, and in consultation. A basic message from this approach is that correct assessment requires measurement of each of the three major inputs, pulmonary arterial pressure (Ppa), pulmonary artery wedge pressure (Pwedge) and cardiac output (CO). Some cases also need left ventricular end diastolic pressure (LVEDP). Other data contributing to analysis will be discussed in each condition. A key to avoiding mistakes is to always remember that PH is simply an elevation in pressure and is not inherently diagnostic of cause.

Pulmonary hypertension and valvular heart disease

Pulmonary hypertension (PH) is an important contributor to morbidity and mortality in patients with left-sided heart disease, including valvular heart disease. In this context, elevated left atrial pressure primarily leads to the development of post-capillary PH. Despite the fact that repair of left-sided valvular heart disease by surgical or interventional approaches will improve PH, recent studies have highlighted that PH (pre- or post-interventional) remains an important predictor of long-term outcome. Here, we review the current knowledge on PH in valvular heart disease taking into account new hemodynamic PH definitions, and the distinction between post- and pre-capillary components of PH. A specific focus is on the precise characterization of hemodynamics and cardiopulmonary interaction, and on potential strategies for the management of residual PH after mitral or aortic valve interventions. In addition, we highlight the clinical significance of tricuspid regurgitation, which may occur as a primary condition or as a consequence of PH and right heart dilatation (functional). In this context, proper patient selection for potential tricuspid valve interventions is crucial. Finally, the article highlights gaps in evidence, and points toward future perspectives.

Operable ventricular septal defect despite severe pulmonary hypertension and cyanosis!

Patients with a significant left-to-right shunt at ventricular level may become inoperable at an early age due to irreversible pulmonary vascular disease. On the other hand, even suprasystemic pulmonary hypertension due to mitral stenosis remains treatable. We report a 24-year-old patient with large ventricular septal defect, severe mitral stenosis and cyanosis who improved after surgical correction of both the lesions. This emphasises the importance of additional post-capillary pulmonary hypertension in Eisenmenger syndrome.

Pulmonary Hypertension Due to Left Heart Disease: an Update

PURPOSE OF REVIEW

Pulmonary hypertension (PH) frequently complicates heart failure and portends a worse prognosis. This review will summarize and discuss recent updates in the classification and management of patients with PH due to left heart disease.

RECENT FINDINGS

Careful hemodynamic assessment is critical to the classification of patients with PH and heart failure. Two hemodynamic subgroups of PH in heart failure patients have been described: isolated post-capillary pulmonary hypertension and combined post- and precapillary pulmonary hypertension. The cornerstone in management of PH due to left heart disease is the treatment of the underlying left heart pathology; however, ongoing trials have been designed to test pulmonary vasodilators in this cohort. PH-specific therapies have not demonstrated a benefit in patients with pulmonary hypertension due to left heart disease. Understanding the distinct pathobiology of each hemodynamic subgroup may lead to the development of useful biomarkers and effective targeted therapies.

Treatment of advanced group 2 PH

Pulmonary hypertension (PH) frequently occurs in patients with left heart disease (LHD), including heart failure with reduced and preserved ejection fraction and valvular heart disease. PH in patients with LHD is associated with worse outcomes making it an attractive target of therapy. Despite the strong rational for treatment, no clear benefits from treating with pulmonary arterial hypertension specific therapies in patients with PH from LHD have been found in clinical trials and some studies have demonstrated harm. Therefore, PH in the setting of LHD should be managed with optimal medical and surgical treatment of LHD and identification and treatment of comorbidities that could contribute to PH. Additionally, significant PH is a contraindication to heart transplantation and, in select patients with left heart failure, left ventricular unloading with prolonged inotrope infusion or left ventricular assist device implantation may successfully reduce pulmonary artery pressures and facilitate transplantation.

Two Cases of Late Shone Syndrome With Pulmonary Hypertension: Heart-Lung Transplant or Valve Surgery?

Two cases of Shone syndrome with severe mitral and aortic valve problems and pulmonary hypertension were referred for heart-lung transplantation. Severely elevated pulmonary vascular resistance (PVR) was confirmed as was severe periprosthetic mitral and aortic regurgitation. Based on the severity of the valve lesions in both patients, surgery was decided upon and undertaken. Both experienced early pulmonary hypertensive crises, one more than the other, that gradually subsided, followed by excellent recovery and reversal of pulmonary hypertension and PVR. These cases illustrate Braunwald's concept that pulmonary hypertension secondary to left-sided valve disease is reversible.

Pulmonary Hypertension in Congenital Heart Disease: Beyond Eisenmenger Syndrome

Patients with adult congenital heart disease have an increased risk of developing pulmonary hypertension. There are several mechanisms of pulmonary hypertension in patients with adult congenital heart disease, and understanding them requires a systematic approach to define the patient's hemodynamics and physiology. This article reviews the updated classification of pulmonary hypertension in patients with adult congenital heart disease with a focus on pathophysiology, diagnostics, and the evaluation of pulmonary hypertension in special adult congenital heart disease populations.

An excellent result of surgical treatment in patients with severe pulmonary arterial hypertension following mitral valve disease

Objective

Observe the efficacy of surgical treatment in patients with severe pulmonary arterial hypertension caused by mitral valve disease.

Methods

We examined the results of surgical treatment in 32 patients with mitral valve disease and severe pulmonary arterial hypertension (pulmonary arterial systolic pressure ≥ 80 mmHg) retrospectively. Operative and postoperative data collection included type of the surgery, cardiopulmonary bypass time, cross-clamp time and the mortality rate. Pulmonary arterial systolic pressure, left atrial diameter, left ventricular end-diastolic diameter, and left ventricular ejection fraction were recorded and compared.

Results

A total number of 32 patients had the operation of mitral valve replacement. Among those subjects, twenty-seven patients were surgically replaced with mechanical prosthesis and five patients with tissue prosthesis. Only one patient died of pneumonia, with a mortality rate of 3.1 %. The statistical results of preoperative and postoperative echocardiographic data showed significant decrease in pulmonary arterial systolic pressure (101.2 ± 20.3 versus 48.1 ± 14.3 mmHg, P < 0.05), left atrial diameter(67.6 ± 15.7 versus 54.4 ± 11.4 mm, P < 0.05) and left ventricular end-diastolic diameter (52.3 ± 9.5 versus 49.2 ± 5.9 mm, P < 0.05). There was no significant change in left ventricular ejection fraction (59.2 ± 6.5 versus 57.9 ± 7.6, P = NS). At the time of follow-up, twenty-eight (96.6 %) patients were classified in New York Heart Association functional class I or II, one(3.4 %) in class III, with the mortality rate is zero percent.

Conclusions

Mitral valve replacement can be performed successfully in patients with mitral valve disease and severe pulmonary arterial hypertension with an acceptable perioperative risk.

Management of severe pulmonary hypertension in patients undergoing mitral valve surgery

OPINION STATEMENT

Pulmonary hypertension (PH) is simply defined as a mean pulmonary artery pressure greater than 25 mmHg at rest; however, may result from varying combinations of abnormal pulmonary artery (PA) blood flow, pulmonary vascular resistance (PVR), PA compliance, and pulmonary venous pressure. Mitral regurgitation (MR) allows for partial transmission of systemic arterial pressure into the pulmonary venous system. Mitral stenosis (MS) prevents pulmonary venous drainage into the left ventricle. In either case, the direct result is marked pressurization of the pulmonary venous system, with the primary cause of PH in significant mitral valve disease (PHMVD) being pulmonary venous hypertension (PVH). Chronic and severe PVH may then lead to muscularization of the pulmonary arterial bed, with a rise in PVR and loss of pulmonary arterial compliance that follows ("reactive" pulmonary vascular disease). Right heart dysfunction ensues once the PVR rises and the compliance falls to a point in which the right ventricle (RV) cannot overcome the increased afterload. However, it is worth emphasizing that in the setting of PHMVD, no matter the degree of mismatch between RV afterload and RV function, the root condition in the patient and cause of the PH remains severe MV disease. Without correction of the primary condition, the patient's heart failure (HF), PH, PVR, and RV dysfunction will remain or progress. Moreover, direct PH medical therapies are ineffective and may actually worsen left heart congestion in the setting of unremediated MVD. Therefore, although surgery may be a higher risk in some patients with PHMVD, the potential benefits justify the risks in the majority of cases. If needed, direct medical management of PH is far simpler and more effective once the MVD is corrected, given the degree of left heart congestion often improves dramatically. Therefore, corrective mitral valve intervention should be considered as the main and definitive treatment for these patients.

Pulmonary hypertension caused by pulmonary venous hypertension

The effect of pulmonary venous hypertension (PVH) on the pulmonary circulation is extraordinarily variable, ranging from no impact on pulmonary vascular resistance (PVR) to a marked increase. The reasons for this are unknown. Both acutely reversible pulmonary vasoconstriction and pathological remodeling (especially medial hypertrophy and intimal hyperplasia) account for increased PVR when present. The mechanisms involved in vasoconstriction and remodeling are not clearly defined, but increased wall stress, especially in small pulmonary arteries, presumably plays an important role. Myogenic contraction may account for increased vascular tone and also indirectly stimulate remodeling of the vessel wall. Increased wall stress may also directly cause smooth muscle growth, migration, and intimal hyperplasia. Even long-standing and severe pulmonary hypertension (PH) usually abates with elimination of PVH, but PVH-PH is an important clinical problem, especially because PVH due to left ventricular noncompliance lacks definitive therapy. The role of targeted PH therapy in patients with PVH-PH is unclear at this time. Most prospective studies indicate that these medications are not helpful or worse, but there is ample reason to think that a subset of patients with PVH-PH may benefit from phosphodiesterase inhibitors or other agents. A different approach to evaluating possible pharmacologic therapy for PVH-PH may be required to better define its possible utility.

An official American Thoracic Society Statement: pulmonary hypertension phenotypes

BACKGROUND

Current classification of pulmonary hypertension (PH) is based on a relatively simple combination of patient characteristics and hemodynamics. This limits customization of treatment, and lacks the clarity of a more granular identification based on individual patient phenotypes. Rapid advances in mechanistic understanding of the disease, improved imaging methods, and innovative biomarkers now provide an opportunity to define PH phenotypes on the basis of biomarkers, advanced imaging, and pathobiology. This document organizes our current understanding of PH phenotypes and identifies gaps in our knowledge.

METHODS

A multidisciplinary committee with expertise in clinical care (pulmonary, cardiology, pediatrics, and pathology), clinical research, and/or basic science in the areas of PH identified important questions and reviewed and synthesized the literature.

RESULTS

This document describes selected PH phenotypes and serves as an initial platform to define additional relevant phenotypes as new knowledge is generated. The biggest gaps in our knowledge stem from the fact that our present understanding of PH phenotypes has not come from any particularly organized effort to identify such phenotypes, but rather from reinterpreting studies and reports that were designed and performed for other purposes.

CONCLUSIONS

Accurate phenotyping of PH can be used in research studies to increase the homogeneity of study cohorts. Once the ability of the phenotypes to predict outcomes has been validated, phenotyping may also be useful for determining prognosis and guiding treatment. This important next step in PH patient care can optimally be addressed through a consortium of study sites with well-defined goals, tasks, and structure. Planning and support for this could include the National Institutes of Health and the U.S. Food and Drug Administration, with industry and foundation partnerships.

WHO's in second?: A practical review of World Health Organization group 2 pulmonary hypertension

World Health Organization (WHO) group 2 pulmonary hypertension (PH) due to left-side heart disease (ie, heart failure or left-sided valvular heart disease) is the most common form of PH in western countries. Distinguishing patients with WHO group 2 PH, particularly the subset of patients with PH due to heart failure with preserved ejection fraction (HFpEF), from those with WHO group 1 pulmonary arterial hypertension (PAH) is challenging. Separating the two conditions is of vital importance because treatment strategies differ completely. Furthermore, therapies that are indicated for WHO group 1 PAH may be harmful in patients with WHO group 2 PH. We review the somewhat confusing PH nomenclature and the WHO classification system and rationale behind it. We then focus on left-side heart disorders that cause PH. An aging population and advances in the medical management of common cardiovascular disorders have caused the prevalence of heart failure to rise significantly, with more than one-half of patients having HFpEF. We review contemporary studies that focus on clinical and echocardiographic findings that help to distinguish HFpEF from PAH in the patient with PH. We discuss the typical, and sometimes atypical, hemodynamic profiles that characterize these two groups, review challenges in the interpretation of data obtained by right-sided heart catheterization, and highlight special maneuvers that may be required for accurate diagnosis. Finally, we review the largely disappointing studies on the use of PAH-specific therapies in patients with WHO group 2 PH, including the use of prostacyclins, endothelin receptor antagonists, and the more promising phosphodiesterase-5 inhibitors.

Pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a chronic and progressive disease leading to right heart failure and ultimately death if untreated. The first classification of PH was proposed in 1973. In 2008, the fourth World Symposium on PH held in Dana Point (California, USA) revised previous classifications. Currently, PH is devided into five subgroups. Group 1 includes patients suffering from idiopathic or familial PAH with or without germline mutations. Patients with a diagnosis of PAH should systematically been screened regarding to underlying mutations of BMPR2 gene (bone morphogenetic protein receptor type 2) or more rarely of ACVRL1 (activine receptor-like kinase type 1), ENG (endogline) or Smad8 genes. Pulmonary veno occusive disease and pulmonary capillary hemagiomatosis are individualized and designated as clinical group 1'. Group 2 'Pulmonary hypertension due to left heart diseases' is divided into three sub-groups: systolic dysfonction, diastolic dysfonction and valvular dysfonction. Group 3 'Pulmonary hypertension due to respiratory diseases' includes a heterogenous subgroup of respiratory diseases like PH due to pulmonary fibrosis, COPD, lung emphysema or interstitial lung disease for exemple. Group 4 includes chronic thromboembolic pulmonary hypertension without any distinction of proximal or distal forms. Group 5 regroup PH patients with unclear multifactorial mechanisms. Invasive hemodynamic assessment with right heart catheterization is requested to confirm the definite diagnosis of PH showing a resting mean pulmonary artery pressure (mPAP) of ≥ 25 mmHg and a normal pulmonary capillary wedge pressure (PCWP) of ≤ 15 mmHg. The assessment of PCWP may allow the distinction between pre-capillary and post-capillary PH (PCWP > 15 mmHg). Echocardiography is an important tool in the management of patients with underlying suspicion of PH. The European Society of Cardiology and the European Respiratory Society (ESC-ERS) guidelines specify its role, essentially in the screening proposing criteria for estimating the presence of PH mainly based on tricuspid regurgitation peak velocity and systolic artery pressure (sPAP). The therapy of PAH consists of non-specific drugs including oral anticoagulation and diuretics as well as PAH specific therapy. Diuretics are one of the most important treatment in the setting of PH because right heart failure leads to fluid retention, hepatic congestion, ascites and peripheral edema. Current recommendations propose oral anticoagulation aiming for targeting an International Normalized Ratio (INR) between 1.5-2.5. Target INR for patients displaying chronic thromboembolic PH is between 2–3. Better understanding in pathophysiological mechanisms of PH over the past quarter of a century has led to the development of medical therapeutics, even though no cure for PAH exists. Several specific therapeutic agents were developed for the medical management of PAH including prostanoids (epoprostenol, trepoprostenil, iloprost), endothelin receptor antagonists (bosentan, ambrisentan) and phosphodiesterase type 5 inhibitors (sildenafil, tadalafil). This review discusses the current state of art regarding to epidemiologic aspects of PH, diagnostic approaches and the current classification of PH. In addition, currently available specific PAH therapy is discussed as well as future treatments.

Management of pulmonary hypertension in left heart disease

Pulmonary hypertension (PH) due to left heart disease is classified as group II according to the Dana Point classification, which includes left ventricular systolic and/or diastolic left heart failure, and left-sided valvular disease. PH due to left heart disease is the most common cause and when present, especially with right ventricular dysfunction, is associated with a worse prognosis. Left heart disease with secondary PH is associated with increased left atrial pressure, which causes a passive increase in pulmonary pressure. Passive PH could be superimposed by an active protective, and in some patients by an ‘out of proportion’, elevated precapillary pulmonary vasoconstriction and vascular remodelling which leads to greater or lesser further increase of the pulmonary artery pressure. In this review, epidemiological and pathophysiologic mechanisms for the development of group II PH are summarized. The conflicting data about the haemodynamic and possible parameters to diagnose passive versus reactive and ‘out of proportion’ PH are presented. The different therapeutic concepts, along with novel treatment strategies, are reviewed in detail and critically discussed regarding their effectiveness and safety.

Pressure reflection in the pulmonary circulation in patients with severe mitral regurgitation indicates adverse postoperative outcome

OBJECTIVES

Severe pulmonary hypertension (PH) is a known risk factor in valvular surgery. In the present study, we hypothesized that the assessment of pressure reflection (PR) in the pulmonary circulation, indicating increased pulmonary vascular resistance, might improve the identification of patients with increased morbidity and mortality following surgery for severe mitral regurgitation.

METHODS

A total of 103 patients without atrial fibrillation were divided into three groups: Group 1 (n = 48), patients without PR; Group 2 (n = 36), patients with PR and pulmonary artery systolic pressure (PASP) ≤ 60 mmHg and Group 3 (n = 19), patients with PR and PASP >60 mmHg. Three variables related to PR were selected: the acceleration time in the right ventricular outflow tract (RVOT), the interval between peak velocity in the RVOT and peak tricuspid regurgitant jet velocity and the right ventricular pressure increase after peak RVOT velocity.

RESULTS

There were no differences between groups in age, ejection fraction, need for coronary bypass grafting or creatinine. Patients with PR (Groups 2 and 3) had more use of vasoactive drugs (overall P < 0.0001, Group 1 vs Group 2 P = 0.018). The proportion of patients with >24 h in the intensive care unit was 27% in Group 1, 54% in Group 2 and 84% in Group 3 (overall P < 0.0001, Group 1 vs Group 2 P = 0.006). The in-hospital mortality in patients without PR (n = 49) was 0% compared with 10.9% in patients with PR (P = 0.029).

CONCLUSIONS

Echocardiography assessment of PR in the pulmonary circulation and severe PH may identify patients with adverse outcome following mitral surgery.

Pulmonary blood flow and pulmonary hypertension: Is the pulmonary circulation flowophobic or flowophilic?

Increased pulmonary blood flow (PBF) is widely thought to provoke pulmonary vascular obstructive disease (PVO), but the impact of wall shear stress in the lung is actually poorly defined. We examined information from patients having cardiac lesions which impact the pulmonary circulation in distinct ways, as well as experimental studies, asking how altered hemodynamics impact the risk of developing PVO. Our results are as follows: (1) with atrial septal defect (ASD; increased PBF but low PAP), shear stress may be increased but there is little tendency to develop PVO; (2) with normal PBF but increased pulmonary vascular resistance (PVR; mitral valve disease) shear stress may also be increased but risk of PVO still low; (3) with high PVR and PBF (e.g., large ventricular septal defect), wall shear stress is markedly increased and the likelihood of developing PVO is much higher than with high PBF or PAP only; and (4) with ASD, experimental and clinical observations suggest that increased PBF plus another stimulus (e.g., endothelial inflammation) may be required for PVO. We conclude that modestly increased wall shear stress (e.g., ASD) infrequently provokes PVO, and likely requires other factors to be harmful. Likewise, increased PAP seldom causes PVO. Markedly increased wall shear stress may greatly increase the likelihood of PVO, but we cannot discriminate its effect from the combined effects of increased PAP and PBF. Finally, the age of onset of increased PAP may critically impact the risk of PVO. Some implications of these observations for future investigations are discussed.

Classification of pulmonary hypertension

Pulmonary hypertension (PH) can develop in association with many different diseases and risk factors, and its presence is nearly always associated with reduced survival. The prognosis and management of PH is largely dependent upon its underlying etiology and severity of disease. The combination of clinical and hemodynamic classifications of PH provides a framework for the diagnostic evaluation of PH to establish a final clinical diagnosis that guides therapy. As our understanding of the different pathologic mechanisms that underlie the syndrome of PH evolves, so too will the classification and treatment of PH.

Pulmonary hypertension associated with left heart disease: characteristics, emerging concepts, and treatment strategies

Left heart disease (LHD) represents the most common causes of pulmonary hypertension (PH). Whether caused by systolic or diastolic dysfunction or valvular heart disease, a hallmark of PH associated with LHD is elevated left atrial pressure. In all cases, the increase in left atrial pressure causes a passive increase in pulmonary pressure. In some patients, a superimposed active component caused by pulmonary arterial vasoconstriction and vascular remodeling may lead to a further increase in pulmonary arterial pressure. When present, PH is associated with a worse prognosis in patients with LHD. In addition to local abnormalities in nitric oxide and endothelin production, gene modifiers such as serotonin polymorphisms may be associated with the pathogenesis of PH in LHD. Optimizing heart failure regimens and corrective valve surgery represent the cornerstone of the treatment of PH in LHD. Recent studies suggest that sildenafil, a phosphodiesterase-5 inhibitor, is a promising agent in the treatment of PH in LHD. Unloading the left ventricle with circulatory support may also reverse severe PH in patients with end-stage heart failure allowing candidacy to heart transplantation.

The impact of pulmonary venous hypertension on the pulmonary circulation in the young

OBJECTIVE AND DESIGN

Pulmonary venous hypertension is a well-characterized cause of pulmonary hypertension in adults, but little is known regarding the relationship between left atrial pressure and pulmonary arteriolar resistance in the young. Also, in adults relief of pulmonary venous hypertension results in a marked fall in pulmonary arteriolar resistance, but this could be different in children because vascular changes are more severe in young patients than adults with mitral stenosis. We inspected records of children at Children's Hospital Boston having mitral balloon valvuloplasty, and patients ≤5 years old having mitral valve replacement, to determine (1) the relationship between left atrial pressure and pulmonary arterial pressure and resistance (n = 94 children, median age 17.8 months) and (2) how pulmonary arteriolar resistance changes after mitral valve replacement.

RESULTS

The average indexed pulmonary arteriolar resistance was 7.8 ± 5.9 units and was unrelated to age but was positively related to left atrial pressure. There was great variability in pulmonary arteriolar resistance for any given left atrial pressure. Pulmonary arterial pressure (n = 16) and pulmonary arterial resistance (n = 9) were measured before and after mitral valve replacement (median = 29.4 months old). Despite preoperative indexed pulmonary arterial resistance of ≥5 units in 11 of 15 patients, postoperative pulmonary arterial pressure was substantially lower in all save three, and two patients with high pulmonary arterial pressure still had high left atrial pressure postoperatively (25 mmHg).

CONCLUSIONS

We conclude that in young children, as in adults, pulmonary arterial resistance generally falls greatly with reduction in left atrial pressure.

Pulmonary hypertension related to left-sided cardiac pathology

Pulmonary hypertension (PH) is the end result of a variety of diverse pathologic processes. The chronic elevation in pulmonary artery pressure often leads to right ventricular pressure overload and subsequent right ventricular failure. In patients with left-sided cardiac disease, PH is quite common and associated with increased morbidity and mortality. This article will review the literature as it pertains to the epidemiology, pathogenesis, and diagnosis of PH related to aortic valve disease, mitral valve disease, left ventricular systolic and diastolic dysfunction, and pulmonary veno-occlusive disease. Moreover, therapeutic strategies, which focus on treating the underlying cardiac pathology will be discussed.

Incidence, epidemiology, and prognosis of residual pulmonary hypertension after mitral valve repair for degenerative mitral regurgitation

Pulmonary hypertension (PH) is a common sequela of degenerative mitral valve disease, but the regression of PH after mitral surgery is often incomplete. We sought to identify the preoperative risk factors for residual PH after mitral valve repair and its effect on the clinical outcome. The outcomes in 71 patients with preoperative PH (mean pulmonary arterial pressure ≥25 mm Hg) were compared according to the presence or absence of residual PH 24 hours after mitral valve surgery. Of 71 patients, 33 (46%) had residual PH. The remainder experienced significant reductions in the mean pulmonary arterial pressure without changes in pulmonary vascular resistance. Patients with residual PH had significantly elevated postoperative pulmonary vascular resistance (despite a significant decrease from the preoperative baseline) compared to those without residual PH. Residual PH was an independent risk factor for postoperative morbidity, mortality, and a prolonged intensive care unit stay (odds ratio 4.0, 95% confidence interval 1.2 to 13.1, p = 0.02), independent of the preoperative mean pulmonary arterial pressure. A decreased left ventricular ejection fraction (odds ratio 0.9, 95% confidence interval 0.8 to 1.0, p = 0.007) and fibroelastic deficiency (odds ratio 3.6, 95% confidence interval 1.1 to 11.8, p = 0.03) were independent predictors of residual PH. In conclusion, residual PH is a clinically important entity common after mitral valve repair for degenerative disease and is associated with clinical variables that aid in the preoperative prediction of at-risk patients.

Serum levels of angiopoietin-1 in patients with pulmonary hypertension due to mitral stenosis

The molecular basis and pathophysiology of pulmonary hypertension (PH) are rapidly evolving areas. Recently discovered angiopoietins (Ang) constitute a family of growth factors, and whether they play a causal or protective role in pulmonary hypertension has not been fully elucidated. Since left heart disease probably represents the most frequent cause of PH, we sought to determine whether there was a relationship between serum Ang-1 levels and pulmonary hypertension caused by mitral stenosis (MS). The study population was composed of 49 patients with isolated MS. These patients were then divided into group 1 [31 patients with severe MS: mitral valve area (MVA) ≤1.1 cm(2)] and group 2 (18 patients with mild-moderate MS: MVA 1.2-2.0 cm(2)). Twenty-one healthy volunteers comprised the control group (group 3). All of the subjects underwent complete transthoracic echocardiography with determination of systolic pulmonary artery pressure (PAPs). Ang-1 levels were determined in serum. Serum levels of Ang-1 were significantly higher in the control group compared to patients with severe (group 1) and mild-moderate (group 2) MS (p < 0.001). Ang-1 levels were found to have moderate inverse correlation with PAPs and left atrial (LA) diameter (r: -0.620, p < 0.001 and r: -0.489, p < 0.001, respectively). The AUC for the ROC curve for predicting PAPs <50 mmHg by serum Ang-1 level was 0.824 (95% CI 0.722-0.926, p < 0.001). A serum level of Ang-1 above 34,656 pg/ml has 74% sensitivity and 80% specificity for predicting that PH is not severe (PAPs <50 mmHg). In conclusion, the findings of this study are distinctive in the sense that they clearly demonstrate a negative correlation between serum Ang-1 levels and the degree of PH.

Pulmonary Vascular Response Patterns to Exercise: Is there a Role for Pulmonary Arterial Pressure Assessment during Exercise in the Post-Dana Point Era?

Pulmonary hypertension (PH) is often diagnosed late in its course when it purports a particularly poor prognosis. Exercise effectively unmasks early forms of several cardiopulmonary diseases but the role of performing pulmonary arterial pressure measurements during exercise in the evaluation of PH remains unclear. Whether pulmonary arterial pressure-flow relationships during exercise may provide a window into earlier diagnosis of functionally significant pulmonary arterial hypertension and left ventricular dysfunction,¹ or add incrementally to our armentarium of diagnostic tests and prognostic indicators in PH, is the topic of active ongoing investigation. Evidence is emerging that abnormal pulmonary arterial pressure response patterns to exercise, when properly indexed to increased blood flow, may help to identify early forms of heart failure and pulmonary arterial hypertension. This article will discuss approaches to performing hemodynamic measurements during exercise as well as the potential clinical utility of identifying normal and abnormal pulmonary vascular response patterns to exercise.

[Pulmonary hypertension and heart failure: the role of pulmonary vasculature]

Left heart disease is the most common cause of pulmonary hypertension. Increased left-sided filling pressure leads to passive postcapillary venous hypertension. In some patients, pulmonary vasoconstriction and vascular remodeling may lead to a further increase in pulmonary pressure. When precapillary hypertension component is associated to left heart failure, the elevation of pulmonary pressure is out of proportion with left atrial pressure: transpulmonary gradient greater than 12 mmHg (mean pulmonary pressure -- mean capillary pressure) and pulmonary vascular resistance greater than three Wood units. Precapillary pulmonary hypertension is common in severe systolic heart failure. Before cardiac transplantation, increased pulmonary vascular resistance greater than 3,5 Wood units are reported in 19 to 35% of patients. In those patients vasoreactivity tests are performed with inotropic and/or systemic and/or pulmonary agents to determine the risk of right heart failure after transplantation. There is no pulmonary vascular resistance level above which transplantation is contraindicated. Cardiac assistance may be used before and after transplantation when pulmonary hypertension is severe and not reversible with conventional treatment and/or pulmonary vasodilators. The contribution of precapillary PH in diastolic heart failure is not known but can be significant and lead to disproportionate PH particularly in elderly. The precapillary component of pulmonary hypertension could be a therapeutic target for specific pulmonary vasodilators. Until now pharmacological trials has been disappointing and those medications can be dangerous because of increasing blood flow to the pulmonary capillaries with a risk of pulmonary edema when left sided pressure are still elevated.

Adventures in cardiovascular research

This article, derived from an invited Distinguished Scientist lecture presented at the American Heart Association Scientific Sessions in 2007, reviews 4 themes (adventures) in clinical cardiovascular research carried out over a period of 58 years. It begins with the author's introduction to cardiovascular hemodynamics during a medical school elective in 1951. The 4 adventures include valvular heart disease, hypertrophic cardiomyopathy, heart failure (HF), and myocardial ischemia. In each of these adventures, the author describes briefly what was known when he entered each field, followed by the author's contribution to the field (the adventure), and ends with comments about the current status of the field. Of particular interest are the changes in the technologies used in clinical cardiovascular research over the past half century, commencing with pressure tracings in left heart chambers with the use of needle puncture in the operating room to genetic technologies designed to understand differences between drugs that inhibit platelet activation. The article ends with some general comments on conducting research and the rewards that can come with this activity.

Updated clinical classification of pulmonary hypertension

The aim of a clinical classification of pulmonary hypertension (PH) is to group together different manifestations of disease sharing similarities in pathophysiologic mechanisms, clinical presentation, and therapeutic approaches. In 2003, during the 3rd World Symposium on Pulmonary Hypertension, the clinical classification of PH initially adopted in 1998 during the 2nd World Symposium was slightly modified. During the 4th World Symposium held in 2008, it was decided to maintain the general architecture and philosophy of the previous clinical classifications. The modifications adopted during this meeting principally concern Group 1, pulmonary arterial hypertension (PAH). This subgroup includes patients with PAH with a family history or patients with idiopathic PAH with germline mutations (e.g., bone morphogenetic protein receptor-2, activin receptor-like kinase type 1, and endoglin). In the new classification, schistosomiasis and chronic hemolytic anemia appear as separate entities in the subgroup of PAH associated with identified diseases. Finally, it was decided to place pulmonary veno-occlusive disease and pulmonary capillary hemangiomatosis in a separate group, distinct from but very close to Group 1 (now called Group 1'). Thus, Group 1 of PAH is now more homogeneous.

Association of the metabolic syndrome with pulmonary venous hypertension

BACKGROUND

Pulmonary venous hypertension (PVH) is a well-described cause of pulmonary hypertension (PH) in patients with left heart disease associated with elevated left heart filling pressure. PVH results from a number of processes, including left-sided valvular disease, constrictive pericardial disease, restrictive cardiomyopathies, and left ventricular (LV) systolic dysfunction. PVH in patients with normal LV systolic function, commonly referred to as diastolic dysfunction, is not well characterized. We observed that many patients with PH due to PVH have obesity, hypertension, diabetes mellitus, and hypercholesterolemia, which are clinical features of the metabolic syndrome (MS), a previously identified cause for systemic vascular disease.

METHODS

We evaluated 122 consecutive patients referred for diagnosis and treatment of PH and compared the prevalence of features of the MS between patients with PVH and those with pulmonary arterial hypertension (PAH). We also compared clinical and hemodynamic characteristics between these two groups.

RESULTS

Compared to patients with PAH, patients with PVH had a higher frequency of hypertension, obesity, diabetes mellitus, and hyperlipidemia. Two or more features of the MS were found in 16 of 17 patients with PVH (94.1%) compared with 34.3% of patients with PAH (p < 0.001; odds ratio, 30.7; 95% confidence interval, 3.6 to 260.0). PH was substantial, but less severe overall, in patients with PVH compared to those with PAH (mean pulmonary artery pressure, 45 +/- 17 mm Hg [range, 26 to 71 mm Hg] vs 53 +/- 10 [range, 33 to 72 mm Hg], respectively [p = 0.041]; and pulmonary vascular resistance, 4.4 +/- 2.9 units [range, 1.2 to 10.8 units] vs 10.8 +/- 4.7 units [range, 4.8 to 21.9 units], respectively [p < 0.001]).

CONCLUSION

PVH is highly associated with the MS. Our results suggest that the MS may predispose patients to develop pulmonary vascular disease.