Francois Haddad

Right heart adaptation to pulmonary arterial hypertension: physiology and pathobiology.

Survival in patients with pulmonary arterial hypertension (PAH) is closely related to right ventricular (RV) function. Although pulmonary load is an important determinant of RV systolic function in PAH, there remains a significant variability in RV adaptation to pulmonary hypertension. In this report, the authors discuss the emerging concepts of right heart pathobiology in PAH. More specifically, the discussion focuses on the following questions. 1) How is right heart failure syndrome best defined? 2) What are the underlying molecular mechanisms of the failing right ventricle in PAH? 3) How are RV contractility and function and their prognostic implications best assessed? 4) What is the role of targeted RV therapy? Throughout the report, the authors highlight differences between right and left heart failure and outline key areas of future investigation.

Risk factors predictive of right ventricular failure after left ventricular assist device implantation.

Right ventricular failure (RVF) after left ventricular assist device (LVAD) implantation appears to be associated with increased mortality. However, the determination of which patients are at greater risk of developing postoperative RVF remains controversial and relatively unknown. We sought to determine the preoperative risk factors for the development of RVF after LVAD implantation. The data were obtained for 175 consecutive patients who had received an LVAD. RVF was defined by the need for inhaled nitric oxide for >/=48 hours or intravenous inotropes for >14 days and/or right ventricular assist device implantation. An RVF risk score was developed from the beta coefficients of the independent variables from a multivariate logistic regression model predicting RVF. Destination therapy (DT) was identified as the indication for LVAD implantation in 42% of our patients. RVF after LVAD occurred in 44% of patients (n = 77). The mortality rates for patients with RVF were significantly greater at 30, 180, and 365 days after implantation compared to patients with no RVF. By multivariate logistic regression analysis, 3 preoperative factors were significantly associated with RVF after LVAD implantation: (1) a preoperative need for intra-aortic balloon counterpulsation, (2) increased pulmonary vascular resistance, and (3) DT. The developed RVF risk score effectively stratified the risk of RV failure and death after LVAD implantation. In conclusion, given the progressively growing need for DT, the developed RVF risk score, derived from a population with a large percentage of DT patients, might lead to improved patient selection and help stratify patients who could potentially benefit from early right ventricular assist device implantation.

Effects of Intracoronary CD34+ Stem Cell Transplantation in Nonischemic Dilated Cardiomyopathy Patients 5-Year Follow-Up

Rationale: CD34+ transplantation in dilated cardiomyopathy was associated with short-term improvement in left ventricular ejection fraction and exercise tolerance. Objective: We investigated long-term effects of intracoronary CD34+ cell transplantation in dilated cardiomyopathy and the relationship between intramyocardial cell homing and clinical response. Methods and Results: Of 110 dilated cardiomyopathy patients, 55 were randomized to receive CD34+ stem cell transplantation (SC group) and 55 received no cell therapy (controls). In the SC group, CD34+ cells were mobilized by granulocyte colony-stimulating factor and collected via apheresis. Patients underwent myocardial scintigraphy and cells were injected in the artery supplying segments with the greatest perfusion defect. At baseline, 2 groups did not differ in age, sex, left ventricular ejection fraction, or N-terminal B-type natriuretic peptide levels. At 5 years, stem cell therapy was associated with increased left ventricular ejection fraction (from 24.3 ± 6.5% to 30.0 ± 5.1%; P=0.02), increased 6-minute walk distance (from 344 ± 90 m to 477 ± 130 m; P<0.001), and decreased N-terminal B-type natriuretic peptide (from 2322 ± 1234 pg/mL to 1011 ± 893 pg/mL; P<0.01). Left ventricular ejection fraction improvement was more significant in patients with higher myocardial homing of injected cells. During follow-up, 27 (25%) patients died and 9 (8%) underwent heart transplantation. Of the 27 deaths, 13 were attributed to pump failure and 14 were attributed to sudden cardiac death. Total mortality was lower in the SC group (14%) than in controls (35%; P=0.01). The same was true of pump failure (5% vs 18%; P=0.03), but not of sudden cardiac death (9% vs 16%; P=0.39). Conclusions: Intracoronary stem cell transplantation may be associated with improved ventricular function, exercise tolerance, and long-term survival in patients with dilated cardiomyopathy. Higher intramyocardial homing is associated with better stem cell therapy response.

The Changing Face of Heart Transplantation

It has been 40 years since the first human-to-human heart transplant performed in South Africa by Christiaan Barnard in December 1967. This achievement did not come as a surprise to the medical community but was the result of many years of early pioneering experimental work by Alexis Carrel, Frank Mann, Norman Shumway, and Richard Lower. Since then, refinement of donor and recipient selection methods, better donor heart management, and advances in immunosuppression have significantly improved survival. In this article, we hope to give a perspective on the changing face of heart transplantation. Topics that will be covered in this review include the changing patient population as well as recent advances in transplantation immunology, organ preservation, allograft vasculopathy, and immune tolerance.

Management strategies for patients with pulmonary hypertension in the intensive care unit

Objective:Pulmonary hypertension may be encountered in the intensive care unit in patients with critical illnesses such as acute respiratory distress syndrome, left ventricular dysfunction, and pulmonary embolism, as well as after cardiothoracic surgery. Pulmonary hypertension also may be encountered in patients with preexisting pulmonary vascular, lung, liver, or cardiac diseases. The intensive care unit management of patients can prove extremely challenging, particularly when they become hemodynamically unstable. The objective of this review is to discuss the pathogenesis and physiology of pulmonary hypertension and the utility of various diagnostic tools, and to provide recommendations regarding the use of vasopressors and pulmonary vasodilators in intensive care. Data Sources and Extraction:We undertook a comprehensive review of the literature regarding the management of pulmonary hypertension in the setting of critical illness. We performed a MEDLINE search of articles published from January 1970 to March 2007. Medical subject headings and keywords searched and cross-referenced with each other were: pulmonary hypertension, vasopressor agents, therapeutics, critical illness, intensive care, right ventricular failure, mitral stenosis, prostacyclin, nitric oxide, sildenafil, dopamine, dobutamine, phenylephrine, isoproterenol, and vasopressin. Both human and animal studies related to pulmonary hypertension were reviewed. Conclusions:Pulmonary hypertension presents a particular challenge in critically ill patients, because typical therapies such as volume resuscitation and mechanical ventilation may worsen hemodynamics in patients with pulmonary hypertension and right ventricular failure. Patients with decompensated pulmonary hypertension, including those with pulmonary hypertension associated with cardiothoracic surgery, require therapy for right ventricular failure. Very few human studies have addressed the use of vasopressors and pulmonary vasodilators in these patients, but the use of dobutamine, milrinone, inhaled nitric oxide, and intravenous prostacyclin have the greatest support in the literature. Treatment of pulmonary hypertension resulting from critical illness or chronic lung diseases should address the primary cause of hemodynamic deterioration, and pulmonary vasodilators usually are not necessary.

The right ventricle in cardiac surgery, a perioperative perspective: II. Pathophysiology, clinical importance, and management.

The importance of right ventricular (RV) function in cardiovascular disease and cardiac surgery has been recognized for several years. RV dysfunction has been shown to be a significant prognostic factor in cardiac surgery and heart transplantation. In the first article of this review, key features of RV anatomy, physiology, and assessment were presented. In this second part, we review the pathophysiology, clinical importance, and management of RV failure in cardiac surgery.

Comparison of Transendocardial and Intracoronary CD34+ Cell Transplantation in Patients With Nonischemic Dilated Cardiomyopathy

Background— In an open-label blinded study, we compared intracoronary and transendocardial CD34+ cell transplantation in patients with nonischemic dilated cardiomyopathy. Methods and Results— Of the 40 patients with dilated cardiomyopathy, 20 were randomized to receive intracoronary injection and 20 received transendocardial CD34+ cell delivery. In both groups, CD34+ cells were mobilized by filgrastim, collected via apheresis, and labeled with technetium-99m radioisotope for single-photon emission computed tomographic imaging. In the intracoronary group, cells were injected intracoronarily in the artery supplying segments of greater perfusion defect on myocardial perfusion scintigraphy. In the transendocardial group, electroanatomic mapping was used to identify viable but dysfunctional myocardium, and transendocardial cell injections were performed. Nuclear single-photon emission computed tomographic imaging for quantification of myocardial retention was performed 18 hours thereafter. At baseline, groups did not differ in age, sex, left ventricular ejection fraction, or N-terminal pro-brain natriuretic peptide levels. The number of CD34+ cells was also comparable (105±31×106 in the transendocardial group versus 103±27×106 in the intracoronary group, P=0.62). At 18 hours after procedure, myocardial retention was higher in the transendocardial group (19.2±4.8%) than in the intracoronary group (4.4±1.2%, P<0.01). At 6 months, left ventricular ejection fraction improved more in the transendocardial group (+8.1±4.3%) than in the intracoronary group (+4.2±2.3%, P=0.03). The same pattern was observed for the 6-minute walk test distance (+125±33 m in the transendocardial group versus +86±13 m in the intracoronary group, P=0.03) and N-terminal pro-brain natriuretic peptide (−628±211 versus −315±133 pg/mL, P=0.04). Conclusions— In patients with dilated cardiomyopathy, transendocardial CD34+ cell transplantation is associated with higher myocardial retention rates and greater improvement in ventricular function, N-terminal pro-brain natriuretic peptide, and exercise capacity compared with intracoronary route. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01350310.

The Right Ventricle in Cardiac Surgery, a Perioperative Perspective: I. Anatomy, Physiology, and Assessment

The importance of right ventricular (RV) function in cardiovascular disease and cardiac surgery has been recognized for several years. RV dysfunction has been shown to be a significant prognostic factor in heart failure, congenital heart disease, valvular disease, and cardiac surgery. In the first of our two articles, we will review key features of RV anatomy, physiology, and assessment. In the first article, the main discussion will be centered on the echographic assessment of RV structure and function. In the second review article, pathophysiology, clinical importance, and management of RV failure in cardiac surgery will be discussed.

Effects of Intracoronary Stem Cell Transplantation in Patients With Dilated Cardiomyopathy

BACKGROUND We investigated clinical effects of intracoronary transplantation of CD34+ cells in patients with dilated cardiomyopathy (DCM). METHODS Of 55 patients with DCM, 28 were randomized to CD34+ transplantation (SC group), and 27 patients did not receive stem cell therapy (controls). In the SC group, peripheral blood CD34+ cells were mobilized by granulocyte-colony stimulating factor and collected via apheresis. Patients underwent myocardial scintigraphy and CD34+ cells were injected in the coronary artery supplying the segments with reduced viability. RESULTS At baseline, the 2 groups did not differ in age, gender, left ventricular ejection fraction (LVEF), or NT-proBNP levels. At 1 year, stem cell therapy was associated with an increase in LVEF (from 25.5 ± 7.5% to 30.1 ± 6.7%; P = .03), an increase in 6-minute walk distance (from 359 ± 104 m to 485 ± 127 m; P = .001), and a decrease in NT-proBNP (from 2069 ± 1996 pg/mL to 1037 ± 950 pg/mL; P = .01). The secondary endpoint of 1-year mortality or heart transplantation was lower in patients receiving SC therapy (2/28, 7%) than in controls (8/27, 30%) (P = .03), and SC therapy was the only independent predictor of outcome on multivariable analysis (P = .04). CONCLUSIONS Intracoronary stem cell transplantation could lead to improved ventricular remodeling, better exercise tolerance and potentially improved survival in patients with DCM.

Characteristics and Outcome After Hospitalization for Acute Right Heart Failure in Patients With Pulmonary Arterial Hypertension

Background— Although much is known about the risk factors for poor outcome in patients hospitalized with acute heart failure and left ventricular dysfunction, much less is known about the syndrome of acute heart failure primarily affecting the right ventricle (acute right heart failure). Methods and Results— By using Stanford Hospitals pulmonary hypertension database, we identified consecutive acute right heart failure hospitalizations in patients with PAH. We used longitudinal regression analysis with the generalized estimating equations method to identify factors associated with an increased likelihood of 90-day mortality or urgent transplantation. From June 1999 to September 2009, 119 patients with PAH were hospitalized for acute right heart failure (207 episodes). Death or urgent transplantation occurred in 34 patients by 90 days of admission. Multivariable analysis identified a higher respiratory rate on admission (>20 breaths per minute; OR, 3.4; 95% CI, 1.5–7.8), renal dysfunction on admission (glomerular filtration rate <45 mL/min per 1.73 m2; OR, 2.7; 95% CI, 1.2–6.3), hyponatremia (serum sodium ⩽136 mEq/L; OR, 3.6; 95% CI, 1.7–7.9), and tricuspid regurgitation severity (OR, 2.5 per grade; 95% CI, 1.2–5.5) as independent factors associated with an increased likelihood of death or urgent transplantation. Conclusions— These results highlight the high mortality after hospitalizations for acute right heart failure in patients with PAH. Factors identifiable within hours of hospitalization may help predict the likelihood of death or the need for urgent transplantation in patients with PAH.