Management of multiple sequential complications following coronary artery bypass grafting: a case report from Tanzania

Abstract

Background

Coronary artery bypass grafting (CABG) is the gold standard treatment for advanced coronary artery disease (CAD). Postoperative complications can be life-threatening, particularly in patients with comorbidities.

Case summary

A 63-year-old male with triple-vessel CAD, diabetes mellitus, hypertension, obesity, and asthma underwent on-pump CABG using bilateral internal mammary artery grafts. The early postoperative course was complicated by traumatic sternal wound dehiscence following a fall on postoperative day 6, resulting in anterior chest wall dehiscence, rib fractures, and displaced sternal wires. Emergency re-exploration and modified Robicsek sternal closure were performed. The patient subsequently developed critical illness polyneuropathy and myopathy overlap syndrome (CIPNM), which gradually improved with supportive management and rehabilitation. He later developed deep sternal wound infection caused by Pseudomonas aeruginosa requiring prolonged targeted antibiotic therapy, repeated debridement, negative pressure wound therapy, removal of sternal wires, and pectoralis major flap reconstruction. Additional complications included arrhythmia, difficult airway management, acute kidney injury, pleural effusion, and electrolyte disturbances, all of which were managed successfully.

Outcome

Following eight months of coordinated multidisciplinary care and rehabilitation, the patient achieved complete wound healing and restored functional capacity.

Discussion/Conclusion

This case illustrates the complexity of sequential post-CABG complications and emphasizes the importance of early recognition, multidisciplinary intervention, and structured rehabilitation in achieving favorable outcomes.

Background

Coronary artery bypass grafting (CABG) is a widely performed surgical intervention for advanced coronary artery disease (CAD), with more than 1 million procedures performed globally each year, including approximately 200,000 procedures annually in the United States [1, 2]. In contrast, the practice remains limited across many African countries, where data on its incidence are scarce [3].

CABG is primarily indicated for patients with significant left main coronary artery disease (> 50% stenosis), triple-vessel disease (> 70% stenosis), or those experiencing severe angina refractory to optimal medical therapy [4]. Despite its well-established benefits in improving myocardial perfusion and reducing ischemic burden, the procedure carries a notable risk of postoperative morbidity and mortality, with an estimated mortality rates of 2% [5]. Commonly documented complications include atrial fibrillation (20%–50%), stroke (1%–2%), sternal wound infection (1%), graft failure, and renal dysfunction (2%–3%), with around 1% of patients requiring dialysis [5].

The present case highlights the complexity of managing multiple postoperative complications following CABG and underscores the importance of early recognition, multidisciplinary management, and coordinated interventions in optimizing patient recovery.

Case presentation

A 63-year-old male with a body mass index (BMI) of 31.8 kg/m² (Class I obesity), and a medical history of asthma (managed with fluticasone propionate–salmeterol inhaler and budesonide inhaler for 20 years), hypertension (on telmisartan/hydrochlorothiazide 40/12.5 mg and amlodipine 5 mg once daily), and type 2 diabetes mellitus (on glimepiride and metformin) presented with a four-year history of progressively worsening shortness of breath on mild exertion. He denied chest pain, lower limb swelling, orthopnea, or a history of alcohol or tobacco use.

Preoperative assessment

Transthoracic echocardiography revealed preserved left ventricular systolic function (LVEF 55%), grade I left ventricular diastolic dysfunction, mitral annular calcification with mild mitral regurgitation, a sclerotic aortic valve with mild aortic regurgitation, and no evidence of pulmonary hypertension. Coronary angiography confirmed triple-vessel coronary artery disease. (Fig. 1) Preoperative laboratory investigations showed preserved renal function with serum creatinine of 101.4 µmol/L and otherwise normal renal profile. Glycemic control was acceptable, with HbA1c of 6.2%, and serum albumin was within normal limits.

Fig. 1.

Coronary angiography findings (A) Left anterior oblique (LAO) cranial view demonstrating complete (100%) occlusion of the mid-right coronary artery (RCA) with Grade III intracoronary collateral circulation. (B) Right anterior oblique (RAO) caudal view showing severe left circumflex artery (LCX) disease with 90% proximal stenosis and 80% mid-segment stenosis distal to the OM2 origin. (C) Right anterior oblique (RAO) cranial view demonstrating severe proximal left anterior descending artery (LAD) stenosis (80%)

The patient’s operative risk, calculated using Euro SCORE II, was 0.73%, indicating a low predicted perioperative mortality risk.

Airway assessment

Intraoperatively, difficult airway management was encountered due to short neck with limited extension of atlantooccipital joint, resulting in poor visualization during direct laryngoscopy. Fiberoptic bronchoscopy and video laryngoscopy were not available at the institution at the time of surgery. Multiple intubation attempts (> 5) using direct laryngoscopy were required, with intermittent mask ventilation for approximately 3–5 min between attempts to maintain oxygenation. Definitive airway control was ultimately achieved using bougie-assisted endotracheal intubation under direct laryngoscopy. No immediate airway trauma or significant desaturation was documented following successful airway securement.

Surgical intervention and early postoperative course

The patient underwent on-pump coronary artery bypass grafting (CABG) using a right internal mammary artery–left internal mammary artery (RIMA–LIMA) Y-graft configuration. The LIMA was anastomosed to the left anterior descending (LAD) artery and the first diagonal branch (D1), while the RIMA was grafted to the obtuse marginal (OM1–OM3) arteries and the posterior descending artery (PDA). (Fig. 2)

Fig. 2.

Intraoperative view of coronary artery bypass grafting RIMA–LIMA Y-graft with six grafts: LIMA to LAD and D1, RIMA to OM1–OM3 and PDA

Total cardiopulmonary bypass time was 157 min, with an aortic cross-clamp time of 140 min. The immediate postoperative course was uneventful. The patient remained on planned mechanical ventilation and was successfully extubated within 24 h following correction of metabolic acidosis and hemodynamic stabilization. He was subsequently transferred from the intensive care unit (ICU) to the surgical ward.

Postoperatively, dual antiplatelet therapy with aspirin (75 mg once daily) and clopidogrel (75 mg once daily) was initiated, along with high-intensity statin therapy and beta-blocker therapy in accordance with standard post-CABG management protocols.

Sternal dehiscence and re-exploration

On postoperative day 6, while being assisted to the restroom by a nurse, the patient attempted to stabilize himself using one hand on the sink while sitting down. He missed the support and fell directly onto his anterior chest against the floor level (approximately 80–90 cm height).

An emergency chest computed tomography (CT) scan revealed a widening of sternal fragments, anterior chest wall dehiscence, three rib fractures and displaced sternal wires. (Fig. 3) He was transferred back to the ICU for surgical management.

Fig. 3.

Axial Non-Contrast CT of the chest showing Postoperative imaging showing widening of sternal fragments, anterior chest wall dehiscence, three rib fractures, displaced sternal wires (A) 3D volume rendered image of the chest showing widening of sternal fragments and displaced sternal wires. (B)

Re-intubation was challenging due to his difficult airway. A re-exploration procedure was performed, and a modified Robicsek sternal closure was undertaken, displaced sternal wires removed with repair of the sternum, subcutaneous tissue, and skin.

Critical illness polyneuropathy and myopathy overlap syndrome (CIPNM)

On postoperative day 9 after CABG (three days after re-exploration), the patient developed critical illness polyneuropathy and myopathy overlap syndrome. Contributing factors included prolonged steroid use, repeated major surgeries within a short period, hypoalbuminemia and exposure to anesthetic and neuromuscular blocking agents. Management included intravenous amino acids and Intramuscular cyanocobalamin (vitamin B12) injection was administered, which resulted in gradual improvement of muscle strength.

Hypoalbuminemia and nutritional deficiencies were corrected with high-protein diet and IV albumin. Pressure ulcers developed during his ICU stay and were managed with topical care. Fluid balance was carefully maintained with diuretics and strict input/output monitoring.

Wound Infection and Subsequent Interventions

The patient recovered steadily and was discharged in stable condition after 17 day postoperatively after CABG. However, 17 days after discharge, he was readmitted with sternal wound dehiscence secondary to a surgical site infection. (Fig. 4A) Wound debridement was performed, and cultures grew Pseudomonas aeruginosa. (Table 1) Targeted antibiotic therapy with piperacillin–tazobactam 4.5 g every 6 h, tigecycline 50 mg every 12 h, and polymyxin B (loading dose 2 million units followed by 1 million units every 12 h) was initiated with intermittent courses of intravenous and intramuscular antibiotics over a nine-month period.

Fig. 4.

(A) Deep sternal wound dehiscence secondary to surgical site infection following CABG. (B) Negative pressure wound therapy (NPWT) applied following surgical debridement. (C) Negative-pressure wound therapy (NPWT) canister showing serosanguineous wound exudate collected after surgical debridement of a surgical site infection

Table 1.

Microbiological culture and antibiotic sensitivity profile of wound and pus swab isolates

Specimen / Source	Microscopy / Gram stain	Organism isolated	Sensitive antibiotics	Resistant antibiotics
Aerobic bacterial culture and sensitivity (wound swab)	Gram-negative rods	Pseudomonas aeruginosa	Piperacillin/Tazobactam	Gentamicin, Ceftazidime, Chloramphenicol, Ciprofloxacin, Meropenem
Pus culture and sensitivity (pus swab)	Gram-negative rods	Pseudomonas aeruginosa	Piperacillin/Tazobactam	Amikacin, Cefepime, Ceftazidime, Ciprofloxacin, Gentamicin, Meropenem

He was subsequently managed with prolonged antibiotic therapy and negative pressure wound therapy (NPWT) over four months. (Fig. 4B) (Fig. 4C) Despite satisfactory healing, a small residual sinus tract persisted. (Fig. 5A) Re-exploration was performed, during which all sternal wires were removed, (Fig. 5B) and pectoralis major muscle flap reconstruction was carried out. (Fig. 5C) Postoperatively, a negative suction drain was maintained due to minimal residual purulent discharge. The wound healed completely within two months. (Fig. 5D)

Fig. 5.

(A) Persistent small sternal sinus tract following prior debridement for post-CABG deep sternal wound infection. (B) Sternal wire removal for infection control and stabilization. (C) Pectoralis major muscle flap reconstruction for definitive sternal wound coverage. (D) Complete wound healing achieved

Acute kidney injury and final outcome

On the 11th day post-readmission, the patient developed acute kidney injury (AKI), necessitating nephrology consultation. (Fig. 6) Management focused on removal of nephrotoxic insults, infection control, and supportive renal care. Potential nephrotoxic agents were identified and adjusted, including dose reduction and subsequent discontinuation of piperacillin–tazobactam and polymyxin B, as well as cessation of atorvastatin, torsemide, and glimepiride. Strict fluid balance monitoring was instituted alongside albumin supplementation during the hypoalbuminemia phase. Electrolyte abnormalities were actively managed, including recurrent hyperkalemia treated with standard medical protocols and metabolic acidosis supported with sodium bicarbonate therapy.

Fig. 6.

Trend of renal function parameters demonstrating acute kidney injury: (A) Serial serum creatinine and estimated glomerular filtration rate (eGFR).(B) Serial blood urea levels

postoperative echocardiography 30 days post CABG demonstrated preserved left ventricular systolic function with a left ventricular ejection fraction (LVEF) of 55% and no definite regional wall motion abnormalities. Postoperative septal motion changes were noted. Mild left ventricular diastolic dysfunction (Grade I) persisted, along with mitral annular calcification associated with mild mitral regurgitation and no mitral Stenosis. Additional findings included mild aortic regurgitation, mild tricuspid regurgitation, and reduced right ventricular systolic function with a tricuspid annular plane systolic excursion (TAPSE) of 13 mm and right ventricular ejection fraction (RVEF) of 45%. No pulmonary hypertension, pericardial effusion, intracardiac thrombus, or valvular vegetations were identified.

Following coronary artery bypass grafting (CABG), the patient had a complicated postoperative course spanning 8 months, characterized by recurrent hospitalizations and necessitating five major surgical procedures. Despite these challenges, he was eventually discharged in stable condition. At present, the patient has resumed normal life at home with family and continues routine outpatient follow-up (Table 2).

Table 2.

Chronological timeline of postoperative complications, interventions, and clinical outcomes following CABG

Date	Event	Major complication/outcome
Day 0	Underwent on-pump CABG using RIMA and LIMA Y-graft configuration (LIMA → LAD/D1, RIMA → OM1/OM2/OM3/PDA). Surgery duration was approximately 6 h.	Difficult airway management due to short neck with limited atlanto-occipital extension. Postoperative metabolic acidosis requiring bicarbonate infusion and vasopressor/inotropic support
Postoperative Day 6	The patient sustained a fall in the ward bathroom while mobilizing. He subsequently developed respiratory distress and bleeding from the sternotomy wound. CT chest revealed widening of sternal fragments, anterior chest wall dehiscence, three rib fractures, and displaced sternal wires. Emergency re-exploration was performed, with removal of sternal wires and modified Robicsek sternal closure	Traumatic sternal wound dehiscence
POD 8–10	Remained mechanically ventilated post re-exploration. patient developed profound generalized weakness with limb power 0/5 despite cessation of sedation	Development of Critical Illness Myopathy and Polyneuropathy overlap syndrome (CIPNM)
POD 11–18	Intensive supportive management including physiotherapy, nutritional optimization, amino acid supplementation, vitamin B12 therapy, pulmonary rehabilitation, and negative fluid balance. Gradual neurological improvement observed	Gradual recovery from CIPNM with improvement of limb power from 0/5 to 5/5. Extubated successfully after prolonged ventilatory support
POD 17	Control CT chest demonstrated minimal upper sternal gapping (< 3 mm) with intact wires and no pleural effusion	Discharged home ambulatory with support.
17 days after discharge	Readmission with sternal wound infection and dehiscence. Surgical exploration revealed slough, necrotic tissue, purulent collection, and exposed sternal wires	Pseudomonas aeruginosa infected sternal wound dehiscence requiring emergency re-exploration, debridement, rewiring, negative-pressure drainage, and escalation of antibiotics
Readmission Day 11	Progressive deterioration in renal function during treatment for severe infection and sepsis. Serum creatinine rose progressively to ~ 692 µmol/L with creatinine clearance ~ 10 mL/min. Nephrology consultation obtained and nephrotoxic antibiotics dose-adjusted/reduced	Development of severe Acute Kidney Injury likely secondary to sepsis, prolonged critical illness, nephrotoxic antibiotics, and multi-organ dysfunction
Months 6–8 post-CABG	Continued inpatient and outpatient wound management with negative pressure wound therapy (NPWT) and prolonged culture-directed antibiotic therapy. At 6 months post-CABG, CT confirmed complete sternal healing and sternal wires were removed. NPWT therapy was continued for wound bed optimization. After 2 weeks, definitive reconstruction was performed using a pectoralis major muscle flap	Chronic postoperative sternal sinus with intermittent discharge, gradually resolving. Final wound closure achieved following staged management including wire removal, NPWT therapy, and muscle flap reconstruction. Overall, the patient underwent five major surgical interventions over an 8-month clinical course

Discussion

Post-CABG complications involve multiple organ systems, including neurological, cardiac, pulmonary, renal, gastrointestinal/hepatobiliary, infectious, endocrine, and psychosocial domains. Risk factors consistently reported across these complications include advanced age, diabetes mellitus, renal impairment, prolonged cardiopulmonary bypass duration, prior cerebrovascular events, chronic obstructive pulmonary disease (COPD), and reduced left ventricular function [6].

Sternal wound complications remain a significant source of morbidity and mortality following coronary artery bypass grafting (CABG). Sternal dehiscence occurs in approximately 0.2% to 5% of patients following CABG, with non-infectious cases reported in about 0.4% to 1% of all cardiac surgeries [7]. Individuals with chronic obstructive pulmonary disease (COPD), diabetes mellitus, obesity, smoking history, are more susceptible to developing sternal wound dehiscence following cardiac surgery [8].

In this case, the initial sternal dehiscence occurred secondary to a fall, representing a mechanical (non-infectious) etiology. Early postoperative falls, although uncommon, can produce catastrophic disruption of recently approximated sternal edges, especially before fibrous healing has occurred, with obesity further increasing mechanical stress and risk of dehiscence.

Several factors contribute to increased fall risk after cardiac surgery, including postoperative weakness, impaired balance, pain, frailty, orthostatic hypotension, reduced mobility, sedative medications, and respiratory compromise. Assessment of fall risk after cardiac surgery should therefore be incorporated into perioperative care. Studies have shown that evaluation of balance, gait, muscle strength, frailty, and prior fall history may help identify patients at high risk for postoperative falls and related complications [9]. Therefore, structured early mobilization, physiotherapy, supervised ambulation, and fall-prevention protocols are essential components of postoperative cardiac surgical care.

Due to persistent sternal instability associated with displaced wires, rib fractures, and anterior chest wall dehiscence, the patient underwent sternal reconstruction using the Modified Robicsek technique The Modified Robicsek procedure is widely recognized as an effective salvage technique for complex sternal instability as it provides enhanced sternal stabilization in patients with fragmented sternum, poor bone quality, recurrent dehiscence, or failed conventional wire closure. Originally described as a reinforcement method for complicated sternal closures, the technique utilizes parasternal interlocking wire fixation combined with transverse peri sternal wires to redistribute mechanical forces across the sternum and reduce wire cut-through [10]. In our patient, reinforced sternal reconstruction was necessary to restore thoracic stability and facilitate respiratory recovery.

Deep sternal wound infections remain among the most serious postoperative complications of cardiac surgery, with mortality rates reported between 10% and 30%. Predisposing factors for sternal wound complications include diabetes mellitus, obesity, chronic obstructive pulmonary disease, osteoporosis, tobacco use, repeat sternotomy, extended intensive care unit stay, and the use of mechanical assist devices [11]. Key preventive measures include optimizing diabetes control, maintaining aseptic techniques, and avoiding bilateral internal mammary artery (IMA) grafting in morbidly obese and poorly controlled DM [12]. In our patient, who had diabetes mellitus, total arterial revascularization was performed using semi-skeletonized BIMA harvesting in an effort to preserve sternal perfusion and reduce the risk of deep sternal wound complications. Several studies have demonstrated that skeletonized or semi-skeletonized BIMA harvesting may mitigate bilateral mammary artery use in diabetic patients. It has been suggested that skeletonization of the internal thoracic arteries preserves sternal vascularization, thereby reducing the incidence of deep sternal wound complications [13]. Furthermore, recent meta-analyses comparing skeletonized and pedicled internal mammary artery harvesting techniques in diabetic patients have shown that while pedicled BIMA harvesting significantly increases the risk of deep sternal wound infection [14], skeletonized or semi-skeletonized BIMA harvesting can be performed safely in carefully selected diabetic patients with meticulous perioperative glycemic control and wound surveillance. Despite appropriate preventive strategies and careful graft harvesting technique, the patient subsequently developed deep sternal wound infection.

Recent evidence-based reviews highlight that once Deep sternal wound infections is suspected, immediate broad-spectrum intravenous antibiotics should be initiated and subsequently tailored according to culture results, but definitive management requires urgent surgical intervention with aggressive debridement of infected and necrotic tissue. Foreign material such as sternal wires should be removed when infection is established, and mediastinal drainage is essential for source control [15]. In our patient, management similarly involved prolonged targeted intravenous antibiotic therapy following identification of Pseudomonas aeruginosa, repeated surgical debridement, removal of infected sternal wires, and prolonged negative pressure wound therapy. Negative pressure wound therapy (NPWT) enhances wound healing by promoting local blood circulation, reducing edema, and facilitating the formation of granulation tissue [16]. Definitive reconstruction is most commonly achieved using vascularized muscle flaps, particularly the pectoralis major flap, which provides well-perfused tissue coverage, reduces recurrence, and improves chest wall stability.

CIPNM, often seen in critically ill patients, results in muscle weakness and prolonged recovery. It is associated with prolonged ICU stay, high-dose corticosteroids, neuromuscular blockers, sepsis, hypoalbuminemia and hyperglycemia [17]. Although the exact incidence of critical illness polyneuropathy and myopathy (CIPNM) in cardiac surgery patients is not well defined, it has been reported in case series following procedures such as CABG, valve surgery, and aortic repair [18]. Cardiac surgery itself is not a direct cause of CIPNM; rather, the development of CIPNM is primarily associated with postoperative critical illness, sepsis, systemic inflammatory response, prolonged mechanical ventilation, and hemodynamic instability [19]. Preventive and supportive strategies include early mobilization, minimizing corticosteroid and neuromuscular blocker exposure, optimizing glycemic control, and reducing excessive sedation where feasible. In this case, CIPNM was managed with supportive therapy, including vitamin B12 supplementation and intravenous amino acid nutritional support. Serial motor power assessment was performed throughout the ICU stay. Neuromuscular blocking agents were avoided, and sedation was minimized and administered only as needed, targeting a Richmond Agitation–Sedation Scale (RASS) score between 0 and − 1 to reduce excessive sedation and delirium/psychosis risk. Gradual neurological and respiratory improvement allowed successful extubation after 7 days.

Postoperative AKI is a recognized complication, particularly in patients with pre-existing kidney disease, diabetes, and prolonged cardiopulmonary bypass [5, 20]. Preventive strategies involve maintaining stable intraoperative perfusion, avoiding nephrotoxic drugs, and optimizing fluid management [21]. Despite these measures, AKI may still occur in critically ill postoperative patients with multiple compounding risk factors. In this patient, AKI likely resulted from a combination of recurrent surgical interventions, severe infection, prolonged intensive care stay, and exposure to nephrotoxic agents. Management focused on elimination of reversible causes, renal support, and strict fluid and electrolyte monitoring.

Conclusion

This case illustrates the complexity of managing multiple postoperative complications following CABG surgery and emphasizes the importance of early recognition and prompt, coordinated multidisciplinary intervention. Despite the prolonged clinical course and recurrent setbacks, timely surgical and medical management, effective teamwork and patient resilience played a crucial role in achieving recovery.

Abbreviations

AKI

Acute kidney injury

BIMA

Bilateral internal mammary artery

CABG

Coronary artery bypass grafting

CIPNM

Critical illness polyneuropathy and myopathy overlap syndrome

COPD

Chronic obstructive pulmonary disease

DM

Diabetes mellitus

ICU

Intensive care unit

IMA

Internal mammary artery

LAD

Left anterior descending artery

LIMA

Left internal mammary artery

LVEF

Left ventricular ejection fraction

NPWT

Negative-pressure wound therapy

VAC

Vacuum assisted Closure

OM

Obtuse marginal artery

OM1

1st obtuse marginal

OM2

2nd obtuse marginal

OM3

3rd obtuse marginal

PDA

Posterior descending artery

POD

Postoperative day

RASS

Richmond Agitation–Sedation Scale

RIMA

Right internal mammary artery

Author contributions

All authors participated in the drafting and revision of the article, reached a consensus on the choice of the journal for submission, provided their final approval for the version to be published, and have committed to being responsible for all aspects of the work.

Funding

No funding was provided in the writing of this case report.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval

The patients provided written informed consent for the publication of this case report and any accompanying images. It’s important to note that institutional approval was not necessary for the preparation of this case report.

Competing interests

The authors declare no competing interests.