Doppler assessment of changes in right-sided cardiac hemodynamics after pulmonary thromboendarterectomy

Echocardiographic diagnosis and clinical implications of wide-open tricuspid regurgitation for evaluating right ventricular dysfunction in the emergency department

The tricuspid regurgitation pressure gradient (TRPG) reflects the difference in pressure between the right ventricle and right atrium (ΔPRV-RA). Its estimation by echocardiography correlates well with that obtained using right-heart catheterization. An elevated TRPG is an important marker for identifying right ventricular dysfunction in both the acute and chronic settings. However, in the "wide-open" variant of TR, the TRPG counterintuitively falls. Failure to recognize this potential pitfall and underlying pathophysiology can cause underestimation of the severity of right ventricular dysfunction. This could lead to erroneous fluid tolerance assessments, and potentially harmful resuscitative and airway management strategies. In this manuscript, we illustrate the pathophysiology and potential pitfall of wide-open TR through a series of cases in which emergency physicians made the diagnosis using cardiac point-of-care ultrasound. To our knowledge, this clinical series is the first to demonstrate recognition of the paradoxically-low TRPG of wide-open TR, which guided appropriate management of critically ill patients in the emergency department.

PATET ratio by Doppler echocardiography: noninvasive detection of pediatric pulmonary arterial hypertension

Pulmonary artery acceleration time (PAT) and PAT: ejection time (PATET) ratio are echocardiographic measurements of pulmonary arterial hypertension (PAH). These noninvasive quantitative measurements are ideal to follow longitudinally through the clinical course of PAH, especially as it relates to the need for and/or response to treatment. This review article focuses on the current literature of PATET measurement for infants and children as it relates to the shortening of the PATET ratio in PAH. At the same time, further development of PATET as an outcome measure for PAH in preclinical models, particularly mice, such that the field can move forward to human clinical studies that are both safe and effective. Here, we present what is known about PATET in infants and children and discuss what is known in preclinical models with particular emphasis on neonatal mouse models. In both animal models and human disease, PATET allows for longitudinal measurements in the same individual, leading to more precise determinations of disease/model progression and/or response to therapy. IMPACT: PATET ratio is a quantitative measurement by a noninvasive technique, Doppler echocardiography, providing clinicians a more precise/accurate, safe, and longitudinal assessment of pediatric PAH. We present a brief history/state of the art of PATET ratio to predict PAH in adults, children, infants, and fetuses, as well as in small animal models of PAH. In a preliminary study, PATET shortened by 18% during acute hypoxic exposure compared to pre-hypoxia. Studies are needed to establish PATET, especially in mouse models of disease, such as bronchopulmonary, as a routine measure of PAH.

Impact of pulmonary thromboendarterectomy on tricuspid regurgitation in patients with chronic thromboembolic pulmonary hypertension: a single-center prospective cohort experience

Background

For patients with chronic thromboembolic pulmonary hypertension (CTEPH) and tricuspid regurgitation (TR) undergoing pulmonary thromboendarterectomy (PTE), whether concomitant tricuspid annuloplasty should be carried out is still controversial.

Methods

The study population consisted of 45 consecutive patients with CTEPH who were scheduled to undergo PTE. All PTE surgeries were conducted with a median sternotomy and deep hypothermia circulatory arrest (DHCA). We collected and analyzed the demographics, surgical details, echocardiographic parameters, and right heart catheterization (RHC) results of these patients.

Results

Moderate to severe TR was documented in 48.9% (22/45) of the patients pre-operatively and 4.4% (2/45) of the patients post-operatively. In patients with grade 4 TR, severity decreased to grade 2 in 8 and to grade 1 in 1. In patients with grade 3 TR, severity decreased to grade 2 in 9, to grade 1 in 3, and 1 remained unchanged. In patients with grade 2 TR, severity decreased to grade 1 in 8, and 15 remained unchanged. The post-operative TR velocity was decreased significantly (431.9±53.4 vs. 196.5±154.0, P<0.001). Pulmonary artery systolic pressure was 84±17 mmHg pre-operatively and decreased to 38±14 mmHg post-operatively (P<0.001). The pre and post-operative pulmonary diastolic pressure was 29±9 and 17±7 mmHg, respectively (P<0.001). The pre and post-operative mean pulmonary pressure was 48±10 and 24±9 mmHg, respectively (P<0.001). The pulmonary vascular resistance (PVR) (1,025.4±465.0 vs. 476.6±181.2 dynes·sec·cm^-5, P<0.001) and pulmonary artery wedge pressure (PAWP) (9±4 vs. 5±2 mmHg, P<0.001) decreased significantly after operation. The cardiac index (CI) increased significantly (1.9±0.5 vs. 2.3±0.4, P=0.003) after operation.

Conclusions

In conclusion, functional TR could be alleviated after PTE even in patients with high PVR. However, the long-term results need to be further investigated.

Fatty acid metabolism in pulmonary arterial hypertension: role in right ventricular dysfunction and hypertrophy

Pulmonary arterial hypertension (PAH) is a complex, multifactorial disease in which an increase in pulmonary vascular resistance leads to increased afterload on the right ventricle (RV), causing right heart failure and death. Our understanding of the pathophysiology of RV dysfunction in PAH is limited but is constantly improving. Increasing evidence suggests that in PAH RV dysfunction is associated with various components of metabolic syndrome, such as insulin resistance, hyperglycemia, and dyslipidemia. The relationship between RV dysfunction and fatty acid/glucose metabolites is multifaceted, and in PAH it is characterized by a shift in utilization of energy sources toward increased glucose utilization and reduced fatty acid consumption. RV dysfunction may be caused by maladaptive fatty acid metabolism resulting from an increase in fatty acid uptake by fatty acid transporter molecule CD36 and an imbalance between glucose and fatty acid oxidation in mitochondria. This leads to lipid accumulation in the form of triglycerides, diacylglycerol, and ceramides in the cytoplasm, hallmarks of lipotoxicity. Current interventions in animal models focus on improving RV dysfunction through altering fatty acid oxidation rates and limiting lipid accumulation, but more specific and effective therapies may be available in the coming years based on current research. In conclusion, a deeper understanding of the complex mechanisms of the metabolic remodeling of the RV will aid in the development of targeted treatments for RV failure in PAH.

Advanced imaging tools rather than hemodynamics should be the primary approach for diagnosing, following, and managing pulmonary arterial hypertension

Pulmonary hypertension (PH) is currently defined based on invasive measurements: a resting pulmonary artery pressure ≥ 25 mm Hg. For pulmonary arterial hypertension, a pulmonary arterial wedge pressure ≤ 15 mm Hg and pulmonary vascular resistance > 3 Wood units are also required. Thus, right heart catheterization is inevitable at present. However, the diagnosis, follow-up, and management of PH by noninvasive techniques is progressing. Significant advances have been achieved in the imaging of pulmonary vascular disease and the right ventricle. We review the current sensitivities and specificities of noninvasive imaging of PH and discuss its role and future potential to replace hemodynamics as the primary approach to screening, diagnosing, and following/managing PH.

Right ventricular plasticity and functional imaging

Right ventricular (RV) function is a strong independent predictor of outcome in a number of distinct cardiopulmonary diseases. The RV has a remarkable ability to sustain damage and recover function which may be related to unique anatomic, physiologic, and genetic factors that differentiate it from the left ventricle. This capacity has been described in patients with RV myocardial infarction, pulmonary arterial hypertension, and chronic thromboembolic disease as well as post-lung transplant and post-left ventricular assist device implantation. Various echocardiographic and magnetic resonance imaging parameters of RV function contribute to the clinical assessment and predict outcomes in these patients; however, limitations remain with these techniques. Early diagnosis of RV function and better insight into the mechanisms of RV recovery could improve patient outcomes. Further refinement of established and emerging imaging techniques is necessary to aid subclinical diagnosis and inform treatment decisions.

Automatic quantification of right ventricular function with gated blood pool SPECT

BACKGROUND

Quantification of right ventricular (RV) function is clinically relevant for the risk stratification and follow-up of patients with a wide spectrum of disease. This can be achieved with electrocardiography-gated blood pool single photon emission computed tomography (GBPS). We aimed to evaluate the accuracy of the completely automatic QBS GBPS processing software as compared with equilibrium planar radionuclide angiography (RNA) and with a GBPS manual segmentation method (GBPS(35%)) for the measurement of global RV ejection fraction (EF), taking the first-pass RNA (FP-RNA) as the gold standard. In parallel, we compared the RVEF, RV end-diastolic volume (EDV), and RV end-systolic volume (ESV) provided by QBS and GBPS(35%).

METHODS AND RESULTS

The population included 85 patients with chronic post-embolic pulmonary hypertension. Twenty-one patients were excluded because of unsuccessful FP-RNA. Intraobserver and interobserver RVEF, RVEDV, and RVESV reproducibilities encountered with planar RNA, QBS, and GBPS(35%) were similar and compared favorably with those calculated with FP-RNA for RVEF. Mean RVEF was different between all methods. RVEF calculated with FP-RNA was better correlated to QBS (r = 0.68) and GBPS(35%) (r = 0.70) than to planar RNA (r = 0.59). RVEDV and RVESV with QBS were lower than with GBPS(35%), by 29% +/- 14% and 36% +/- 13%, respectively. RVEDV and RVESV with QBS were highly correlated to corresponding GBPS(35%) values: r = 0.88 and r = 0.91, respectively.

CONCLUSION

As opposed to FP-RNA, GBPS is highly successful for the quantification of RV function. Both QBS and GBPS(35%) provide RVEF values similarly well correlated to FP-RNA and performed better than planar RNA. RVEF, RVEDV, and RVESV provided by QBS and GBPS(35%) are highly correlated. All of these RV functional measurements require further validation versus a better gold standard before their accuracy can be established.

Tricuspid valvular disease in the patient with chronic pulmonary thromboembolic disease

Chronic thromboembolic pulmonary hypertension is associated with right ventricular dilatation, high right-sided filling pressures, and functional tricuspid regurgitation. The tricuspid regurgitation resulting from this disease has been postulated to be caused by tricuspid annular dilatation with displacement of the papillary muscles. Pulmonary endarterectomy is an operation that corrects the pulmonary hypertension resulting from chronic thromboemboli. As a result of this operation, most patients show significant improvement in tricuspid valve function. Thus, pulmonary endarterectomy is one of the few cardiac operations in which surgery remote to a valve restores valve function. This review analyzes the factors responsible for changes in tricuspid valve regurgitation after pulmonary endarterectomy and provides a strategy to predict the small subset of patients who will not show improvement in tricuspid valve function after this operation.

Operative classification of thromboembolic disease determines outcome after pulmonary endarterectomy

OBJECTIVE

We sought to determine whether type and location of thromboembolic disease in the pulmonary vascular tree predicts the hemodynamic result and clinical outcome in patients undergoing pulmonary endarterectomy.

METHODS

From 1998 to 2000, 202 patients with pulmonary hypertension and pulmonary vascular resistance ranging from 194 to 2950 dynes-s-cm(-5) underwent pulmonary endarterectomy. Preoperative and postoperative tricuspid valve function, pulmonary artery pressure, and pulmonary vascular resistance were determined by means of transthoracic echocardiography and measurements with a Swan-Ganz catheter (Edwards Lifesciences, Irvine, Calif), respectively. Patients underwent intraoperative classification of thromboembolism as follows: type 1 (76 patients), fresh thrombus in the main-lobar pulmonary arteries; type 2 (81 patients), intimal thickening and fibrosis proximal to the segmental arteries; type 3 (38 patients), disease within distal segmental arteries only; and type 4 (7 patients), distal arteriolar vasculopathy without visible thromboembolic disease.

RESULTS

Overall perioperative mortality was 4.5% (9/202 patients). By means of univariate analysis, patients with type 3 or 4 disease (distal pulmonary vasculopathy) had more residual postoperative tricuspid regurgitation (P <.0001), higher postoperative pulmonary artery systolic pressure (P <.0001), and greater postoperative pulmonary vascular resistance (P <.0001) compared with that seen in patients with type 1 or 2 disease, in whom thromboembolic disease was more surgically accessible. Factors such as severity of preoperative tricuspid regurgitation, patient age, and circulatory arrest time had no correlation with postoperative hemodynamic improvement. Patients with distal thromboembolic disease (type 3-4) had higher perioperative mortality, required longer inotropic support, and had longer hospital stays compared with patients with type 1 or 2 thromboembolic disease.

CONCLUSION

The degree of improvement in pulmonary hypertension and tricuspid regurgitation after pulmonary endarterectomy is determined by the type and location of pulmonary thromboembolic disease. Classification of thromboembolism is useful for predicting patient outcome after pulmonary endarterectomy.

Assessment of cardiac performance using Tei indices in patients undergoing pulmonary thromboendarterectomy

BACKGROUND

This study was designed to evaluate left and right ventricular performance using Tei indices in patients with severe chronic thromboembolic pulmonary hypertension undergoing pulmonary thromboendarterectomy (PTE). The Doppler-derived indices are easily measurable indicators of ventricular function based on nongeometric assessment, which helps overcome some of the difficulties entailed in the geometric assessment of left ventricular (LV) and right ventricular (RV) function in pulmonary hypertension.

METHODS

The indices were derived for 24 patients (aged 54+/-14 years) before and after PTE. Calculation of these indices was based on the duration of two time intervals using the formula (A - B)/B, where A is the interval between cessation and onset of mitral inflow (or tricuspid inflow) and B is LV or RV ejection time. In addition, LV and RV end-diastolic and end-systolic chamber areas were determined using two-dimensional echocardiography, and systolic function was calculated. Mean pulmonary artery pressure was determined invasively.

RESULTS

PTE led to a significant reduction of mean pulmonary artery pressure (46+/-10 versus 25+/-6 mm Hg; p < 0.05). LV and RV indices were abnormally high before surgery, declined significantly afterwards, and then almost matched normal values (0.61+/-0.26 versus 0.37+/-0.18; p < 0.05 and 0.55+/-0.22 versus 0.37+/-0.13; p < 0.05). Geometric assessment of the left and right ventricle also showed impaired systolic function before PTE, with significant improvement after surgery.

CONCLUSIONS

LV and RV Tei indices allow a quantitative assessment of ventricular function in patients undergoing PTE. Lower indices after surgery reflect an improvement of the previously impaired cardiac function. Our results emphasize the value of PTE in the treatment of chronic thromboembolic pulmonary hypertension.

Improvement of tricuspid regurgitation after pulmonary thromboendarterectomy

BACKGROUND

For patients with chronic thromboembolic pulmonary hypertension who undergo pulmonary thromboendarterectomy (PTE) it has not yet been systematically investigated how operation affects the severity of tricuspid regurgitation (TR). This study sought (1) to evaluate the extent of TR reversibility after operation, (2) to identify potential predictors of the reversibility of TR, and (3) to investigate the influence of geometric and hemodynamic alterations on the extent of TR severity.

METHODS

Thirty-nine patients (55+/-12 years) undergoing PTE without tricuspid valve repair were investigated before and 13+/-8 days after operation by Doppler color flow mapping. Geometry of the tricuspid valve as well as right ventricular size and function were determined with echocardiography. Mean pulmonary arterial pressure was determined invasively.

RESULTS

After PTE, mean pulmonary arterial pressure was significantly lower (48+/-10 versus 25+/-7 mm Hg, p < 0.05). Most of the patients had a distinct reduction of TR, and the improvement trend showed on the severity scale: number of patients with 4+TR (23 --> 4), 3+TR (12 --> 12), 2+TR (2 --> 13), and 1+TR (2 --> 10). Examination after PTE revealed profound reduction of right ventricular size and annulus diameter, with a normalization of the valvular geometry. However, none of the study variables were useful as indicators of the postoperative outcome.

CONCLUSIONS

After PTE without additional valve repair most patients show significantly reduced severity of TR soon afterward; the very few cases in which TR does not improve remain unidentifiable before operation. Our recommendation is consequently to refrain from additional tricuspid repair in patients undergoing PTE.

Diagnosis of pulmonary arterial hypertension and pulmonary embolism with magnetic resonance angiography

BACKGROUND

Pulmonary magnetic resonance angiography (PMRA) has been proven to be accurate for the diagnosis of suspected acute or chronic pulmonary embolism (PE). Only limited data exist on the reliability of PMRA for the diagnosis of acute and chronic pulmonary artery hypertension (PAH). The aim of this study was to determine the accuracy of PMRA in the differentiation between patients suffering from PAH of varying etiologies.

METHODS

Fifty patients (21 women; mean [+/- SD] age, 52 +/- 16 years) were examined with gadolinium-enhanced PMRA for the evaluation of pulmonary artery (PA) disease. The diagnosis of PAH (ie, systolic PA pressure of > 35 mm Hg) was determined by Doppler echocardiography. The criteria for the diagnosis of chronic PAH by PMRA were dilated central PAs (diameter > 28 mm) and abnormal proximal-to-distal tapering of the PAs. The diagnostic criterion for acute and chronic PE was the presence of an intravascular filling defect.

RESULTS

Chronic PAH was present in 18 patients, which was correctly identified by PMRA in 16 patients (sensitivity, 89%). All patients without PAH had normal findings on PMRA (specificity, 100%). Only 1 of 18 patients with normal findings on PMRA showed moderate chronic PAH (negative predictive value, 94%). PAH due to acute/subacute pulmonary thromboembolism (15 patients) was identified in all patients (sensitivity, 100%). Acute PAH was differentiated from chronic PAH in all cases by the detection of intravascular filling defects and the lack of abnormal proximal-to-distal tapering of PAs.

CONCLUSIONS

PMRA is a promising noninvasive imaging modality for the identification of patients with acute or chronic PAH. This technique should be considered a sensitive and highly specific screening tool for suspected chronic PAH.

Pathophysiology of impaired right and left ventricular function in chronic embolic pulmonary hypertension: changes after pulmonary thromboendarterectomy

STUDY OBJECTIVES

This study sought to evaluate the pathophysiology of left and right heart failure in patients with chronic thromboembolic pulmonary hypertension (CTEPH) who were hospitalized to undergo pulmonary thromboendarterectomy (PTE).

DESIGN

Thirty-nine patients (16 women and 23 men; mean +/- SD age, 55+/-12 years) with severe CTEPH were examined before and 13+/-8 days after PTE by way of transthoracic echocardiography and right heart catheterization.

MEASUREMENTS AND RESULTS

Examination results confirmed in all cases that before surgery the right ventricles were enlarged and systolic function was impaired. Moderate to severe tricuspid valve regurgitation was observed. Left ventricular eccentricity indexes reflected a leftward displacement of the interventricular septum. End-diastolic left ventricular size and systolic function had decreased, and the left ventricular filling pattern showed impaired diastolic function. After surgery, mean pulmonary artery pressure was significantly lower (48+/- 10 mm Hg vs. 25+/-7 mm Hg; p<0.05). The calculated end-diastolic and end-systolic right ventricular areas had decreased: 30+/-7 cm(2) vs 21 +/-5 cm(2) (p<0.05) and 24+/-6 cm(2) vs. 14+/-4 cm(2) (p<0.05), respectively. Right ventricular fractional area change had increased (20+/-7% vs. 33+/-8%; p<0.05). Most of the patients exhibited a marked decrease in the severity of tricuspid regurgitation. Septal motion, left ventricular systolic function, and diastolic filling pattern returned to normal values (early to late diastolic left ventricular inflow ratio, 0.70+/-0.33 vs. 1.35+/-0.51; p<0.05). The mean cardiac index also improved (2.7+/-0.6 L/min/m(2) vs. 3.7+/-0.8 L/min/m(2)).

CONCLUSIONS

In CTEPH, functions are impaired in the right as well as the left ventricles of the heart. Improved lung perfusion and the reduction of right ventricular pressure overload are direct results of PTE, which in turn bring a profound reduction of right ventricular size and a recovery of systolic function. Normalization of interventricular septal motion as well as improved venous return to the left atrium lead to a normalization of left ventricular diastolic and systolic function, and the cardiac index improves.

Nitric oxide: an important role in the maintenance of systemic and pulmonary vascular tone in man

AIMS

The aim of this study was to examine whether nitric oxide (NO) has an important role in maintaining basal vascular tone in normal man by examining the effects of nitric oxide inhibition using N(G)-monomethyl-L-arginine (L-NMMA) on systemic and pulmonary haemodynamics.

METHODS

Ten normal male volunteers 26 +/- 1.6 years were studied on two separate occasions in a double-blind, placebo controlled crossover study. They were randomised to receive either a continuous infusion of L-NMMA (4 mg kg(-1) h(-1)) with a front loaded bolus (4 mg kg(-1)) or volume matched placebo. Pulsed wave Doppler echocardiography was used to measure cardiac output (CO), mean pulmonary artery pressure (MPAP) and hence systemic vascular resistance (SVR) and total pulmonary vascular resistance (TPR). Measurements were made prior to infusion (t0) and after 4, 8, and 12 min (t1, t2 and t3).

RESULTS

Infusion of L-NMMA significantly increased mean arterial blood pressure (MAP), SVR and TPR and significantly reduced heart rate (HR), stroke volume (SV) and CO compared to placebo. These effects were observed at t1 and persisted during the entire infusion period.

CONCLUSIONS

These results are consistent with a role for basal nitric oxide generation in the maintenance of basal systemic and pulmonary vascular tone in normal man.

Effects of long-term infusion of prostacyclin (epoprostenol) on echocardiographic measures of right ventricular structure and function in primary pulmonary hypertension. Primary Pulmonary Hypertension Study Group

BACKGROUND

Right heart failure is an important cause of morbidity and mortality in primary pulmonary hypertension. In a recent prospective, randomized study of severely symptomatic patients, treatment with prostacyclin (epoprostenol) produced improvements in hemodynamics, quality of life, and survival. This article describes the echocardiographic characteristics of participants in this trial; the relationship of echocardiographic variables to hemodynamic parameters, exercise capacity, and quality of life; and the echocardiographic changes associated with prostacyclin therapy.

METHODS AND RESULTS

The 81 patients enrolled in this multicenter trial were randomized to treatment with a long-term infusion of prostacyclin in addition to conventional therapy (n = 41) or conventional therapy alone (n = 40) for 12 weeks. Echocardiograms and assessments of hemodynamics, exercise capacity, and quality of life were performed before and after the treatment phase. On baseline evaluation, patients had marked right ventricular dilatation and dysfunction, abnormal septal curvature, and significant tricuspid regurgitation with a high regurgitant velocity. Pericardial effusions were common. More pronounced abnormalities in right heart structure and function were associated with higher pulmonary arterial and mean right atrial pressures, lower cardiac index, and impaired exercise capacity but had no predictable relationship to quality-of-life indicators. The 12-week infusion of prostacyclin had beneficial effects on right ventricular size, curvature of the interventricular septum, and maximal tricuspid regurgitant jet velocity.

CONCLUSIONS

The echocardiographic manifestations of severe primary pulmonary hypertension reflect abnormalities in hemodynamics and exercise capacity. Prostacyclin has beneficial effects on right heart structure and function that may contribute to the clinical improvement and prolonged survival observed with this drug.

Right ventricular pathology in chronic pulmonary hypertension

Right ventricular free wall biopsy specimens in 40 patients undergoing surgery for relief of chronic thromboembolic pulmonary hypertension were normal in 5%, disclosed only myocyte hypertrophy in 80%, mild focal fibrosis in 12.5%, and myocarditis in 2.5%. There was no relation between postsurgical functional or hemodynamic outcomes and the presence of focal fibrosis.

Microbubbles as novel pressure-sensitive MR contrast agents

Magnetic resonance imaging contrast agents that are sensitive to pressure would be useful for evaluating cardiovascular function. One such potential contrast agent consists of gas-filled liposome microbubbles. The magnetic susceptibility of the microbubbles locally perturb the static magnetic field, which influences the transverse-relaxation properties of the surrounding medium. Changes in the pressure alter the bubble dimensions, which affects the magnetic field perturbations and, hence, the transverse-relaxation. The effect of these microbubbles on the T2 relaxation times of a water-based medium was measured for liposomes filled with different gases-nitrogen, argon, air, oxygen, xenon, neon, perfluoropentane, perfluorobutane, and sulfur hexafluoride. The air-filled, perfluoropentane-filled and the oxygen-filled liposomes demonstrated the largest effect on transverse-relaxation. The influence of pressure on both gradient-echo and spin-echo signal intensities for air-filled microbubbles was also evaluated. Pressure-induced changes in signal intensity were consistently observed for both the spin-echo and gradient-echo pulses sequences.

Automatic Border Detection to Assess Right Ventricular Function Following Surgical Treatment of Thromboembolic Pulmonary Hypertension

Automatic border detection (ABD) has been developed as a potentially useful means for evaluating ventricular function on line in an automatic fashion. Its success with tracking left ventricular function is established, but little is known about its ability to assess right ventricular (RV) function. Accordingly, 20 patients with severe pulmonary hypertension due to chronic thromboembolic disease underwent standard two-dimensional echocardiography and imaging with ABD before and after pulmonary thromboendarterectomy to correct pulmonary hypertension. ABD-derived results were compared to manually planimetered RV areas calculated from the apical four-chamber view. Doppler tricuspid regurgitant velocity fell significantly with surgery from 4.4 +/- 0.6 to 2.9 +/- 0.7 m/sec (P < 0.001). The mean values for RV areas derived by manual planimetry and ABD were similar, as was fractional area shortening, which improved significantly with surgery (manual 0.24 +/- 0.01 preoperative vs 0.31 +/- 0.11 postoperative, P < 0.05; and ABD 0.19 +/- 0.05 preoperative vs 0.32 +/- 0.15 postoperative, P < 0.001). There was, however, very little correlation between the individual values for ABD versus manually derived RV areas and fractional area shortening, with the best correlation being the RV end-diastolic areas after surgery (y = 0.684x + 7.9, r = 0.564, P = 0.01). These results demonstrate that both manually planimetered RV areas and those determined by ABD can adequately follow changes in ventricular function over time. However, variability within each technique may prevent direct comparison of the absolute values of the two techniques. (ECHOCARDIOGRAPHY, Volume 13, March 1996)

Unidirectional valve patch for repair of cardiac septal defects with pulmonary hypertension

BACKGROUND

Congenital septal defects with a large left-to-right shunt often cause pulmonary hypertension, which complicates surgical repair of the defects.

METHODS

Twenty-four patients with congenital cardiac septal defects and severe pulmonary hypertension had operation to close the septal defect using a unidirectional valve patch during a 3-year period. The ratio of systolic pulmonary artery pressure to systolic arterial blood pressure was near to or more than 1.0 in all patients.

RESULTS

Two patients died in the hospital after operation, and there have been no deaths during intermediate term follow-up. Mean pulmonary artery pressure decreased from 80 +/- 12 mm Hg to 56 +/- 18 mm Hg. The ratio of pulmonary artery pressure to systemic arterial pressure dropped from 1.1 +/- 0.1 mm Hg to 0.7 +/- 0.1 mm Hg. The unidirectional valve patch functioned allowing right to left shunting in 4 patients with a systolic pulmonary artery pressure more than systolic arterial blood pressure immediately after closure of a septal defect. The patch sealed or was effectively closed by the third postoperative day. There was impressive improvement in symptoms and exercise tolerance after operation during the 3-month to 3-year (mean, 1.1 year) follow-up period.

CONCLUSIONS

The unidirectional valve patch is useful for management of patients having operation to close cardiac septal defects in the presence of severe pulmonary hypertension.

Recovery of the right ventricle after single-lung transplantation in pulmonary hypertension

Single-lung transplantation has been successfully performed in patients with pulmonary fibrosis and emphysema. In contrast, patients with end-stage pulmonary hypertension (either primary or secondary to Eisenmenger's syndrome) have conventionally been offered heart-lung transplantation. The rationale underlying this approach is that chronic pulmonary hypertension results in irreversible right ventricular dilatation and failure. Recovery of the right ventricle has previously been reported after thromboendarterectomy for chronic large-vessel pulmonary embolism, correction of atrial septal defect or mitral valve replacement. The evolution of right ventricular morphology and function after lung transplantation has not been previously described. This study examines the reversibility of right ventricle dysfunction following normalization of pulmonary artery pressure after single-lung transplantation in 4 patients with pulmonary hypertension. Cardiac function was assessed using electrocardiography, echocardiography and radionuclide angiography. Pulmonary hemodynamic measurements, including pulmonary artery pressure and pulmonary vascular resistance, decreased in all patients after single-lung transplantation. Electrocardiographic changes observed were leftward shift in the QRS axis, and a decrease in P-wave amplitude and in right ventricular force. Echocardiographic examination revealed decreased right atrial, right ventricular and tricuspid valve annular dimensions, normalization of septal motion, and decreased tricuspid regurgitation. Thus, improved pulmonary hemodynamics after single-lung transplantation for pulmonary vascular disease results in reversal of right heart dilatation and dysfunction, and improved myocardial performance. The extent of right ventricular dysfunction beyond which recovery is unlikely to occur has yet to be determined.

The pulmonary artery acceleration time determined with the MR-RACE-technique: comparison to pulmonary artery mean pressure in 12 patients

The goal of our study was to evaluate a rapid noninvasive MR technique for quantification of the pulmonary artery acceleration time (PAT) and other parameters of pulmonary hemodynamics and to correlate with pulmonary artery mean pressure (mPAP). The PAT known as "time-to-peak" out of Doppler echocardiographic measurements normally shows significant inverse correlation with mPAP. With the MR-RACE-Technique (RACE: Real time ACquisition and Evaluation of motion) blood velocity measurements can be obtained with a total acquisition time of a few seconds. The application of this technique to the pulmonary artery has not been reported before. Out of the RACE velocity wave form PAT can be obtained with a temporal resolution of about 15 ms. To explore the relationship between PAT and mPAP, right heart catheterization and MR-RACE measurements were performed in 12 patients with different pulmonary vascular abnormalities. Results of MR-RACE were compared with those of mPAP measured by right heart catheter and showed significant inverse correlation (r = -0.82, p = .0011, n = 12). The ability of MR-RACE to enable measurements of blood flow with profiles may be important for characterizing pulmonary and cardiovascular abnormalities.

Doppler estimation of changes in pulmonary artery pressure during hypoxic breathing

To assess the use of Doppler echocardiographic screening for abnormal pulmonary vasoreactivity, we measured pulmonary artery pressure in 10 adult patients and 11 normal subjects while recording Doppler right ventricular outflow acceleration time, pre-ejection period, and ejection time. In the normal subjects we also measured the changes in each parameter after 10 minutes of hypoxic breathing (FIO2 = 0.12). Mean pulmonary artery pressure increased by 39% during hypoxia (13 +/- 4.3 to 18 +/- 5.4 mm Hg). In the patients and normal subjects at rest, mean pulmonary artery-pressure correlated well with acceleration time (r = -0.84; standard error of the estimate, 6.6 mm Hg; p = 0.0001). Over the narrow range of mean pulmonary artery pressure in normal subjects at rest, mean pulmonary artery pressure did not correlate well with acceleration time, acceleration time/pre-ejection period, or acceleration time/right ventricular ejection time. However, changes in mean pulmonary artery pressure induced by hypoxic breathing did correlate with changes in acceleration time/right ventricular ejection time (r = 0.73; standard error of the estimate, 2.3 mm Hg; p = 0.01). Doppler ultrasound may offer a noninvasive means for detecting abnormal pulmonary vasoreactivity in asymptomatic individuals at risk for developing pulmonary hypertension.

Chronic cor pulmonale

Chronic cor pulmonale is defined as right heart hypertrophy and/or chronic right heart failure. There are many etiologies, but the common cause is increased right heart work from pulmonary hypertension. Etiology can be conveniently discussed by assuming two prototypes, the asphyxial or hypoxic type and the vascular obliterative type. A common cause of the asphyxial type is chronic obstructive pulmonary disease, and the obliterative type is represented by chronic pulmonary thromboembolic disease or primary pulmonary hypertension. Pathology is discussed, emphasizing the cardiac manifestations of chronic cor pulmonale including data of specific cardiac chamber size. An overview of hemodynamics is given, and the use and limitation of electrocardiography and chest x-rays are discussed. The exciting potential use of echocardiography for the serial non-invasive measurement of anatomical and pathophysiological features is outlined, along with the value of a careful physical examination and the proper utilization of laboratory tests in the diagnosis of chronic cor pulmonale. In the patient with the asphyxial type, the treatment of pulmonary infectious exacerbations, the role of corticosteroids, digoxin, diuretics, phlebotomy, bronchodilators (theophylline, beta adrenergic agonists, and anticholinergics), and long-term oxygen therapy is noted. The controversy surrounding the use of vasodilators and calcium blockers in these patients is discussed. Treatment aspects of the vascular obliterative type, including the role of vasodilators, calcium blockers, prostacyclin, anticoagulants, and overall strategy are discussed. A brief note is mentioned of the promising role of surgical therapy in chronic thromboembolic disease causing chronic cor pulmonale.